Southeastern Catalysis Society

16th Annual Fall Symposium

Four Points by Sheraton Hotel

Asheville, North Carolina

September 24th and 25th , 2017

The following companies have provided generous financial sponsorship for this symposium

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Southeastern Catalysis Society 16th Annual Fall SymposiumFour Points by Sheraton Hotel

Asheville, North CarolinaSeptember 24th and September 25th, 2017

Sunday, September 24th

12:00 pm Badge and Booklet Pick-up Begins (Lobby)

1:00 pm Poster Session and Cash Bar (Chop House)

3:00 pm Break

3:20 pm Postdoc Presentations (Ballroom)

Chair: Neeraj Rai

5:26 pm Break

5:44 pm Pre-Dinner Faculty Presentations (Ballroom)

Chair: TBD

6:56 pm Dinner (Ballroom)

7:56 pm Invited Speaker: Ahmad Moini (Ballroom)

BASF Corporation, Iselin, NJ, USA

"Novel Zeolite Catalysts for Diesel Emission Applications"

8:56 pm Conclude/ Announcements

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Monday, September 25th

7:30 am Coffee and Load Talks

8:00 am Oral Presentations (Session 1) (Ballroom)

Chair: AJ Medford

10:06 am Break

10:24 am Oral Presentations (Session 2) (Ballroom)

Chair: Hongliang Xin

11:54 am Lunch (Chop House)

1:30 pm Oral Presentations (Session 3) (Ballroom)

Chair: Joshua Tong

2:30 pm Break

2:48 pm Oral Presentations (Session 4) (Ballroom)

Chair: Carlos Alberto Carrero Marquez

4:00 pm Adjourn

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Southeastern Catalysis Society 16th Annual Fall SymposiumSunday, September 24th, 2017

1:00 PM to 3:00 PM

Technical Program - Poster Presentations

#1 (F/S) - Hydrogen Transfer Reactions of Furfural over Perovskite Catalysts; Michelle K. Kidder,Alberto Villa and Ashi Savara; Oak Ridge National Lab

#2 (F/S) - Kinetic Analyses for Bridging the Pressure Gap: Liquid-Solid and Gas-Solid Small AlcoholOxidation; Aditya (Ashi) Savara, Yafen Zhang, David R. Mullins, Michelle Kidder; Oak Ridge NationalLab

#3 (P) - Developing Structure-Activity Relationships of N2 Reduction on Ni Nanocatalysts ; Liang Yu,Junwei Luo and Hongliang Xin; Virginia Polytechnic Institute and State University

#4 (P) - Impacts of Novel Bio-fuel Components on Commercial Three-way Catalysts; Sreshtha SinhaMajumdar and Josh Pihl; Oak Ridge National Lab

#5 (P) - High Loading and Well Dispersed Carbon Supported Pt and Ru Catalysts Prepared byStrong Electrostatic Adsorption; Natthapong Pongpichayakul, Sebastian Torres Pacheco, John MeynardM. Tengco and John R. Regalbuto; University of South Carolina

#6 (P) - Catalytic Properties and Activities of LaMnO3(100) and La0.7Sr0.3MnO3(100) Thin Films inAlcohol Oxidation; Yafen Zhang, Aditya Savara and David Mullins; Oak Ridge National Lab

#7 (S) - Hydrodeoxygenation of Phenol Over an NiMoP Catalyst: A Density Functional Theory Study;Alicia Brown, Varsha Jain and Neeraj Rai; Mississippi State University

#8 (S) - Machine Learning Feed Forward Network for Single Site Metal Cation Catalysts; AndrewSamstag, Dr. Steven Pellizzeri and Dr. Rachel B. Getman; Clemson University

#9 (S) - Mechanocatalytic Hydrogenolysis and Hydrolysis of Diphenyl Ether; Andrew Tricker, RohanKadambi, Alex Brittain and Carsten Sievers; Georgia Tech University

#10 (S) - Determination and Enhancement of the Synergistic Effects of ReOx-Pd/CeO2 for ImprovedDeoxydehydration of Organic Compounds; Elizabeth Barrow, Stephanie Sanchez and Jochen Lauter-bach; University of South Carolina

#11 (S) - Synthesis and Reactivity of Supported Pt Single Atoms and Small Clusters for CO Oxida-tion; Chun-Te Kuo, Yubing Lu, Xiwen Zhang and Ayman M. Karim; Virginia Polytechnic Institute and StateUniversity

#12 (S) - Semiconducting Layered Heterostructures for Photocatalytic Reduction of CO2; DebtanuMaiti, Johnnie Cairns, Venkat R. Bhethanabotla and John N. Kuhn; University of South Florida

#13 (S) - An ATR-IR study of CO Adsorption on Pt Supported Catalysts in Different Solvents; EricHusmann and Ayman M. Karim; Virginia Polytechnic Institute and State University

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#14 (S) -Kinetic Monte Carlo Simulation of Direct Propylene Epoxidation on Supported Gold Nanopar-ticles; Jingjing Ji, Zheng Lu, Yu Lei and C. Heath Turner; The University of Alabama

#15 (S) - PdFe Bimetallic Catalysts for the Hydrodeoxygenation of p-Cresol; Jeremiah Lipp, FahadAlmalki and John R. Regalbuto; University of South Carolina

#16 (S) - Synthesis of Ruthenium Based Hollandite Catalyst for Ammonia Decomposition; Katie Mc-Cullough and Jochen Lauterbach; University of South Carolina

#17 (S) - Understanding Structural Influence on Multicarbon Formation in CO2 Electroreduction;Emily Marx, Siwen Wang and Hongliang Xin; Virginia Tech University

#18 (S) -Combinatorial Study of Cu-Ag Based Ethylene Epoxidation Catalysts; Kathleen Mingle, JohnWelsh and Jochen Lauterbach; University of South Carolina

#19 (S) - Elevated Temperature Photocatalytic Production of Hydrocarbons from CO2 and H2O;Morghan Parker, Samiksha Poudyal and Siris Laursen; University of Tennessee

#20 (S) - Hierarchical MFI-Zeolite Catalysts for Glycerol Acetylation; Qandeel Almas, Carsten Sieversand Christopher W. Jones; Georgia institute of Technology

#21 (S) - Tuning the Selective Hydrogen Combustion Properties of Mn-based Redox Catalysts; RyanB Dudek, Yunfei Gao, Junshe Zhang and Fanxing Li; North Carolina State University

#22 (S) - Mg6MnO8 based Redox Catalysts for Oxidative Dehydrogenation of Ethane via a CyclicRedox Scheme; Seif M. Yusuf, Luke M. Neal and Fanxing Li; North Carolina State University

#23 (S) - Tri-Reforming of Methane over NiCe@SiO2 Yolk-Shell Nanotube Catalysts; Sunkyu Kim,Bradie S. Crandall, Erdem Sasmaz and Jochen Lauterbach; University of South Carolina

#24 (S) - Large-Scale Nonadiabatic Molecular Dynamics Enabled by Machine Learning; Jiamin Wang,Liang Yu, Hirohito Ogasawara, Frank Abild-Pedersen and Hongliang Xin; Virginia Tech University

#25 (S) - Theoretical Investigation of the Pt Catalyzed Hydrodeoxygenation of Succinic Acid to 1,4-Butanediol; Wenqiang Yang, Muhammad Osman Mamun, Andreas Heyden; University of South Carolina

#26 (S) - Alkali Promoted Lanthanum Strontium Ferrite for Oxidative Dehydrogenation of EthaneUnder a Cyclic Redox Scheme; Yunfei Gao, Luke M. Neal and Fanxing Li; North Carolina State University

#27 (S) - SO2 Poisoning of Cu-SSZ-13 for NH3-SCR: Mechanistic Study and Kinetic Model Develop-ment; Yasser Jangjou, Di Wang, Ashok Kumar, Junhui Li and William S. Epling; University of Virginia

#28 (S) - A Bayesian-Learned Newns-Anderson Model for Understanding Hydrogen Evolution onMetals; Zheng Li, Wei Shan Chin, Siwen Wang, Shih-Han Wang, Hongliang Xin; Virginia Polytechnic In-stitute and State University

#29 (S) - Dual-Phase Co-Ionic Membranes by Solid-State Reactive Sintering Method for CatalystsSupporter; Zeyu Zhao, Shenglong Mu, Dong Jiang and Jianhua Tong; Clemson University

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Postdoc and Faculty Presentations3:20 pm to 6:56 pm

Ballroom

3:20 pm "Approaching the 150◦C Challenge with Passive Trapping Materials and HighlyActive Oxidation Catalysts" Andrew J. Binder, Eleni Kyriakidou, Todd J. Toops andJames E. Parks II; Oak Ridge National Laboratory

3:38 pm "Synergy of Photo-Excitation and Surface Catalysis over Ceria-Based Materialsfor Enhanced Photocatalysis" Dong Jiang, Wenzhong Wang and Jianhua Tong; Clem-son University

3:56 pm "Promoted Perovskites for Methane Partial Oxidation in Absences of Gaseous Ox-idants" Luke M. Neal, Arya Shafiefarhood and Fanxing Li; NC State University

4:14 pm "Sulfur Interactions with Pd and Pt catalysts: Precious Metal Crystallite Size De-pendence" Monique Shauntá Wilburn and William S. Epling; University of Virginia

4:32 pm "Controlling Reaction Selectivity through the Surface Termination of PerovskiteCatalysts" Felipe Polo-Garzon, Shi-Ze Yang, Victor Fung, Guo Shiou Foo, Elizabeth E.Bickel, Matthew F. Chisholm, De-en Jiang and Zili Wu; Oak Ridge National Laboratory

4:50 pm "Computationally-Driven Design of Cation-Based Catalysts for Ethene Conver-sions" Steven Pellizzeri, Pere Miró, Varinia Bernales, Melissa Barona, Peilin Liao,Laura Gagliardi, Randall Q. Snurr and Rachel B. Getman; Clemson Univeristy

5:08 pm "Synthesis of Highly Activity Fuel-cell Catalysts for Direct Methanol Fuel Cells"Bahareh Alsadat Tavakoli Mehrabadi, John W. Weidner, John R. Regalbuto and John R.Monnier; University of South Carolina

5:26 pm Break Time

5:44 pm "Computational Insights into Photo(electro)chemical Nitrogen Fixation over Tita-nia Catalysts" Andrew J. Medford, Benjamin C. Comer and Marta C. Hatzell; GeorgiaInstitute of Technology

6:02 pm "Mixed Oxide Based Redox Catalysts for Methane Partial Oxidation via a CyclicRedox Scheme " Fanxing Li; North Carolina State University

6:20 pm "Development and Implementation of High-throughput Gas Chromatography viaEthylene Epoxidation" Erdem Sasmaz, Garrett Buchman, Kate Mingle and JochenLauterbach ; University of South Carolina

6:38 pm "Design, Synthesis and Kinetics of Solid Catalysts for Sustainable HydrocarbonsActivation: Exploring Synergistic Effects in Heterogeneous Catalysis" Carlos A.Carrero; Auburn University

6:56 pm Dinner Time

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Invited Lecture

Novel Zeolite Catalysts for Diesel Emission Applications

Ahmad Moini

BASF Corporation, Iselin, NJ, USA

Automotive exhaust conditions present unique challenges for the design of effective catalysts. In additionto the need for catalytic activity over a wide temperature range, the catalyst must show durability towardsextreme hydrothermal aging conditions. The use of zeolitic materials under such conditions is especiallychallenging due to the vulnerability of zeolites to steam aging. The BASF discovery of the Cu-CHA catalystfor selective catalytic reduction (SCR) of NOx demonstrated an effective balance between favorable activesites and zeolite framework durability. It also paved the way for the implementation of urea SCR as the keyapproach for NOx reduction in diesel vehicles. This presentation will highlight the development of Cu-CHAas the leading technology for diesel emission applications. Specific focus will be placed on the synthesisand structural features of the zeolite. In addition, there will be a discussion of specific characterization andmodeling approaches focusing on the unique attributes of the metal active sites and the interaction of thesemetal species with the zeolite framework.

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Southeastern Catalysis Society 16th Annual Fall SymposiumMonday, September 25th, 2017

Technical Program - Oral Presentations

8:00 am "Catalyst Development for Large Scale Conversion of Landfill Gas to Liquid Fu-els" Xianhui Zhao, Paul Stachurski, Devin Walker, Tim Roberge, Matthew Kastelic, Shri-nand Shah, Babu Joseph and John N. Kuhn; University of South Florida

8:18 am "Enhanced CO2 Conversion to CO by Silica Supported Perovskite Oxides atLow Temperatures" Bryan J. Hare, Debtanu Maiti, Yolanda A. Daza, Venkat R.Bhethanabotla and John N. Kuhn; University of South Florida

8:36 am "Low Temperature CO2 Conversion to CO Using Earth Abundant Perovskite Ox-ides" Debtanu Maiti, Bryan J. Hare, Yolanda A. Daza, Adela E. Ramos, Venkat R.Bhethanabotla and John N. Kuhn; University of South Florida

8:54 am "Guided Mixed-Oxide Synthesis for Ethane Partial Oxidation" Juan Jimenez, KateMingle, Teeraya Bureerug, Cun Wen and Jochen Lauterbach; University of South Car-olina

9:12 am "Aqueous-phase Hydrogenation of Succinic Acid Using Bimetallic Ir-Re/C Cata-lysts" Jayson Keels, Xiao Chen, Changhai Liang, John Monnier and John Regalbuto;University of South Carolina

9:30am "Solvation Effects on MWW-2D Zeolite Framework for Dissociation of β -O-4Linkage" Varsha Jain and Neeraj Rai; Mississippi State University

9:48 am "ALD Modified Au-Based Catalysts for Propylene Epoxidation" Zheng Lu, Zili Wu,C. Heath Turner and Yu Lei; The University of Alabama in Huntsville

10:06 am Break Time

10:24 am "Benchmarks for CO and CO2 Adsorption on MnO(100): a Comparison of DFT toExperimental Data" Han Chen, Xu Feng and David F. Cox; Virginia Tech

10:42 am "Selective Oxidation of n-Butane to 1-Butanol over Transition Metal Catalysts En-capsulated by Metal-Organic Frameworks" Jiazhou Zhu and Rachel Getman; Clem-son University

11:00 am "Using Scaling Relationships to Efficiently Calculate Thermodynamic and KineticQuantities Involved in the Aqueous Phase Reforming (APR) of Glycerol" TianjunXie; Clemson University

11:18 am "Control of the Activation towards Unsaturated C-C Bonds over Ni-based Inter-metallic Compounds" Yuanjun Song, Yang He and Siris Laursen; University of Ten-nessee

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11:36 am "Molecular Simulation Study of How the Structure of Liquid Water Affects theFree Energies of Reaction in Aqueous Phase Heterogeneous Catalysis" XiaohongZhang and Rachel B. Getman; Clemson University

11:54 am Lunch Time

1:00 pm "Determining How Support pH and Hydrophilicity Influence Activity and ProductDistributions in Aqueous Phase Reforming of Glycerol" Torrie E. Sewell, David A.Bruce and Rachel B. Getman; Clemson University

1:18 pm "Effect of Synthesis Methods on the Performance of NiO/CexZr1−xO2 CatalystsConverting Methane to Higher Alcohols" Yimeng Lyu, Chukwuemeka Okolie, BenDeglee and Carsten Sievers; Georgia Institute of Technology

1:36 pm "Orbitalwise Coordination Numbers as New Descriptors for Oxygen ReductionCatalyst Design" Siwen Wang and Hongliang Xin; Virginia Tech

1:54 pm "Additive Manufacturing of Solid Oxide Fuel Cell Stacks" Shenglong Mu, YuzheHong, Jincheng Lei, Zeyu Zhao, Dong Jiang, Phaneuf Vincent, Fei Peng, Hai Xiao andJianhua Tong; Clemson University

2:12 pm "The Effects of Long Term Sulfur Exposure on Three Way Catalyst Performancein Passive Selective Catalytic Reduction Systems" Calvin R. Thomas, Josh A. Pihl,Jochen A. Lauterbach and Todd J. Toops; University of South Carolina

2:30 pm Break Time

2:48 pm "Stabilization of Catalytic Surfaces Using Bimetallic Core-Shell Structures" An-drew P. Wong, John Tengco, Arthur Reber, Sonia Eskandari, Shiv Khanna, John R. Mon-nier and John R. Regalbuto; University of South Carolina

3:06 pm "Catalytic Activities of Ag-Ir/Al2O3 Bimetallic Catalysts Prepared by ElectrolessDeposition" Sonia Eskandari, Andrew Wong, John Meynard Tengco, Abolfazl Shakouri,John R. Regalbuto and John R. Monnier; University of South Carolina

3:24 pm "Development of Continuous Electroless Deposition for the Synthesis of BimetallicCatalysts" Gregory L. Tate, Methasit Juthathan and John R. Monnier; University ofSouth Carolina

3:42 pm "Vacancy Creation Energy in Mn-containing Perovskites: an Indicator for Chem-ical Looping with Oxygen Uncoupling" Amit Mishra, Fanxing Li and Erik Santiso;North Carolina State University

4:00 pm Adjourn

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Poster Presentation Abstracts

#1

Hydrogen Transfer Reactions of Furfural over Perovskite Catalysts

Michelle K. Kidder, Alberto Villa and Ashi Savara

Oak Ridge National Lab

Catalytic transfer hydrogenation is attractive because a donor solvent is used in place of gaseous H2 to alle-viate the inconvenience and expense and help with the safety of using gaseous H2. This type of reaction isuseful in many organic synthetic reactions and applied in industrial processes, such as reduction of ketonesand imines to alcohols and amines. Transfer hydrogenation practices, typically are done with high pressuredvessels with H2 and over toxic reagents, such as copper chromite. More recently, a wide variety of ho-mogenous metals have been investigated for the catalytic transfer hydrogenation processes, typically madeof complex hydrides and metal-catalyzed hydrogenations. However, reduction rates are difficult to controlwith these types of catalysts and the catalysts tend to deactivate. Heterogenous catalysts have the advan-tages of easy recovery, recycling of the catalyst and minimizing toxic waste, but are not selective towardsfunctional groups such as -CO, CX and NO2. Perovskite-type mixed-oxides have not been explored broadlyfor the application of catalytic transfer hydrogenations and have focused on aromatic nitro compounds intoaromatic amines. We explore the reduction of an aldehyde via hydrogen transfer reactions over perovskitecatalysts, which a search of the literature has concluded that nothing has been published in this regard. Animportant model reaction to study is the hydrogenation of furfural. It has been shown that specific interme-diate steps for conversion of furfural is catalytically structure sensitive and impacts product selectivity. Thusthe aim is to have mechanistic understanding based on morphology of the catalyst, and reaction conditions,such as solvent effects, which will allow us to design catalysts to drive product selectivity and activity forthis type of reaction base on the information gained for the importance of the interaction between catalyst,hydrogen donor and the acceptor molecule and the results will presented here.

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#2

Kinetic Analyses for Bridging the Pressure Gap: Liquid-Solid and Gas-Solid Small AlcoholOxidation

Aditya (Ashi) Savara, Yafen Zhang, David R. Mullins and Michelle Kidder

Oak Ridge National Lab

One of the objectives of our research is to connect the kinetics and mechanisms of surface chemistry undervacuum pressures (VP) on 1 cm2 flat crystals, to that which occurs under ambient pressure (AP) conditionson nanoparticles and powders. Here, we present one of our success stories (liquid-solid benzylic alcoholoxidation on precious metal nanoparticles), and an ongoing study (gas-solid small alcohol oxidation overcomplex metal oxides).

In the first example, kinetic simulation + fitting of experimental data was used to close the pressure gap inaerobic benzylic alcohol oxidation over precious metal nanoparticles (Pd and AuPd). Prior to this three-paper study, the mechanism and kinetics of aerobic benzylic alcohol oxidation over the precious metalnanoparticles was not known, despite the potential for sustainable industrial aldehyde production. A mecha-nism was constructed based on knowledge from VP single crystal studies, and refined using transient kineticsdata. It was determined that the mechanism split into two pathways to reach the six products observed: A) analkoxy pathway leading to toluene, benzaldehyde, and benzyl ether, and B) a carbonyloxyl pathway ("neu-tral carboxylate") leading to benzoic acid, benzene, and benzyl benzoate. With this mechanism, the firstmicro-kinetic modeling of benzylic alcohol oxidation over the precious metal nanoparticles was conducted;this may be the first study over any catalyst to show consistency with a realistic sticking coefficient formicro-kinetic modeling in a liquid-solid heterogeneous catalysis reaction. Finally, micro-kinetic modelingshowed that that the role of Au was to weaken the oxygen-surface interaction, leading to a lower oxygensurface coverage.

In a second example, the oxidation of small alcohols (methanol, ethanol, and isopropanol) over complexmetal oxides is being studied. LaMnO3 and LaxSr1-xMnO3 show suitable activity to study the alcohol oxi-dation selectivity with single crystal samples under VP conditions, and also packed bed powders under APconditions. We are gaining kinetic parameters under both sets of conditions, where we vary the flux/pressureand temperature. The VP steady state experiments are conducted using an effusive molecular beam. The in-tent is to connect both the mechanisms and the kinetics between the pressure ranges in a global mechanisticand kinetic model, and to understand the cooperativity by varying the cationic La/Sr ratio.

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#3

Developing Structure-Activity Relationships of N2 Reduction on Ni Nanocatalysts

Liang Yu, Junwei Luo and Hongliang Xin

Virginia Polytechnic Institute and State University

The industrial production of NH3 almost exclusively relies on the longstanding technology known as theHaber-Bosch process [1]. This technology, unfortunately, is energy-intensive and requires exceedingly hightemperature and pressure (above 300◦C and 125 atm), consuming over 30 GJ per ton of NH3 produced, ac-companied with the inevitable and significant carbon emission in the process of generating hydrogen fromsteam reforming. It is imperative to develop alternative processes that offer true sustainability in the econ-omy of ammonia synthesis. Electrochemical N2 reduction reaction (N2RR) for NH3 synthesis has beenregarded as a promising alternative route to the Haber-Bosch industrial process [2]. Using electricity sup-plied from a renewable source, this process can provide a way of making NH3 with substantially reducedenergy consumption and carbon emission.

Density functional theory studies reveal that the key reaction intermediates in electrochemical N2 reductionon metals are *N2H, *NH2, and *H [4]. Depending on the reactivity of surfaces, the limiting potential isdetermined by the formation of *N2H for relatively non-reactive surfaces and the formation of *NH2 or hy-drogenation of *NH2 for reactive ones. The linear adsorption-energy scaling relations between those specieson metal surfaces result in the high overpotential and poor faradaic efficiency due to the competing hydro-gen evolution reaction (HER). Understanding the structural effect of catalytic active sites on local chemicalreactivity can guide us in the computer-based optimizing and designing of novel catalyst for the reaction. Inthis poster, using Ni as the non-noble catalyst which sits closest to the top of the N2RR activity volcano, wepresent the dependence of electrocatalytic activity/selectivity on the local coordination of Ni sites, aimingto shed light on the structural effect in the electrochemical NH3 synthesis.

References:1. H. Liu, Chin. J. Catal. 35, 1619 (2014).2. V. Kyriakou, I. Garagounis, E. Vasileiou, A. Vourros, and M. Stoukides, Catal. Today 286, 2 (2017).3. J. H. Montoya, C. Tsai, A. Vojvodic, and J. K. Nφ rskov, ChemSusChem 8, 2180 (2015).4. E. Skúlason, T. Bligaard, S. Gudmundsdóttir, F. Studt, J. Rossmeisl, F. Abild-Pedersen, T. Vegge, H.Jónsson, and J. K. Nφ rskov, Phys. Chem. Chem. Phys. 14, 1235 (2012).

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#4

Impacts of Novel Bio-fuel Components on Commercial Three-way Catalysts

Sreshtha Sinha Majumdar and Josh Pihl

Oak Ridge National Lab

To simultaneously reduce petroleum consumption and carbon-footprint of spark ignition (SI) engines, novelbiofuel components are being developed in parallel with designing highly efficient engines. For abatementof emissions from modern light-duty vehicles operating under stoichiometric conditions to meet the strin-gent environmental regulations, three-way catalysts (TWC) have been very effective. When calibrated undertypical engine exhaust conditions, criteria pollutants such as nitrogen oxides (NOx), non-methane organicgases (NMOG) and carbon monoxide are efficiently removed with the TWC by converting them into N2,CO2 and H2O. The TWC aftertreatment system, however, is only active above a critical temperature knownas the catalyst light-off temperature. Until the catalyst is sufficiently heated to the light-off temperature (coldstart), the abovementioned criteria pollutants escape the engine exhaust into the atmosphere. As these pol-lutants are deemed green-house gases and have deleterious effects on the environment, it is very importantthat the bio-fuels under consideration light-off at a temperature at or below the TWC light-off temperatureto minimize slip out of the vehicle exhaust.

In this study, a commercial TWC from a spark-ignition light-duty vehicle has been hydrothermally agedas per industry guidelines. The light-off behavior, of several bio-fuel components down-selected based ontheir compatibility with current engine infrastructure and operating conditions, on these aged TWC coreswere investigated. A bench-scale reactor system controlled by LabVIEW software and fitted with a vapordelivery module (VDM), Fourier transform infra-red (FTIR), flame ionization detector (FID) and a massspectrometer (MS) has been used to conduct and analyze these experiments as per protocol set by industry.The effect of fuels of different functional groups, such as alkanes, alkenes, alcohols, ketones, esters, ethersand aromatic hydrocarbons, on the light-off temperature has been studied. Within each functional groupconsidered, the effect of structure of these hydrocarbons, whether straight chain, branched or cyclic, hasbeen examined. The impact of the hydrocarbon light-off behavior on the carbon monoxide and total NOxconversions have also been investigated.

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#5

High Loading and Well Dispersed Carbon Supported Pt and Ru Catalysts Prepared by StrongElectrostatic Adsorption

Natthapong Pongpichayakul 1, Sebastian Torres Pacheco 2, John Meynard M. Tengco 3 and John R.Regalbuto 3

1. Chang Mai University, Chang Mai, Thailand2. University of Puerto Rico Mayaguez, Puerto Rico

3. University of South Carolina, Columbia, South Carolina, USA

Catalysts are used for enhancing the rate of chemical reactions and many methods have been developedto prepare catalysts. Strong Electrostatic Adsorption (SEA) is a simple method to produce well-dispersedsupported metal nanoparticle catalysts. In this work, SEA was used to prepare platinum and ruthenium sup-ported on carbon. The carbon support, Darco G-60, was oxidized before being used as support, resulting inlower point of zero charge (PZC). For SEA on supports having acidic PZC, cationic metal complexes wereused as precursors: Tetraamineplatinum(II) hydroxide hydrate (PTA-OH) and Hexaamineruthenium(III)chloride (RuHA-Cl) for Pt and Ru, respectively. Support surface uptake due to electrostatic adsorption wasdetermined to be optimal in basic pH range.

Maximum surface density for both Pt and Ru in a single SEA cycle was limited to 0.8 µmol/m2. This corre-sponds to a metal loading of 8.5% for Pt or 4.5% for Ru after moderate thermal reduction. To increase metalloading, multiple uptake-reduction cycles were done. This procedure was repeated three times for Pt andfour for Ru, measuring the resulting metal loading each cycle. The final catalysts had around 2.5 µmol/m2

final loading. For characterization, X-ray diffraction, electron microscopy, and chemisorption were used toestimate the average size of metal particles. There was significant discrepancy for size estimates betweenthe characterization methods likely due to carbon overlayer formation during synthesis, as corroborated bytemperature programmed oxidation experiments. The small particle size estimates obtained suggest SEA isa viable method for preparing catalysts with high metal loading and good dispersion.

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#6

Catalytic Properties and Activities of LaMnO3(100) and La0.7Sr0.3MnO3(100) Thin Films in AlcoholOxidation

Yafen Zhang, Aditya Savara and David Mullins

Oak Ridge National Lab

ABO3 perovskite-type mixed catalysts have been extensively studied due to their great flexibility with re-spect tailoring their redox properties. The activities of two perovskite surfaces, LaMnO(100) (LMO(100))and La0.7Sr0.3MnO3(100) (LSMO(100)) were evaluated for the oxidation of methanol, ethanol, and iso-propanol by using temperature-programmed desorption/reaction (TPD/TPR). TPD results show that the ma-jor hydrocarbon product of the alcohol reactions on LMO(100) are aldehydes or ketones resulting fromdehydrogenation. However, ethanol or isopropanol exhibits a larger amount of acetaldehyde or acetone pro-duction compared to formaldehyde from methanol. In addition, ethanol and isopropanol lead to formationof a small amount of alkenes. The product distribution from TPD suggests that the breakage of β C-Hbonds is easier than that of C-O or β C-H bonds on LMO(100). TPD spectra of alcohols from LSMO(100)show that alcohol mostly desorbs molecularly and no other gas-phase products were observed above 200◦C.This suggests that alkoxy is weakly bound to the surface metal cation on LSMO(100) compared with thaton LMO(100). TPR results indicate that LMO(100) appears to be redox/basic for methanol reaction sinceit mainly produces CO and H2, while the surface exhibits acidic/redox properties during ethanol and iso-propanol oxidation since they mostly undergo dehydrogenation at low temperatures (below 300◦C) andmainly produce alkenes at elevated temperatures (above 300◦C). In addition, for the methanol reaction onLMO(100), the surface becomes less basic and more redox in the presence of O2 compared with that in theabsence of O2, as evidenced by much less H2 production and more formaldehyde formation below 400◦C.TPR results for LSMO(100) indicate that the surface appears to be more acidic with increasing O2 concen-tration.

This work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences,Chemical Sciences, Geosciences, and Biosciences Division.

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#7

Hydrodeoxygenation of Phenol Over an NiMoP Catalyst: a Density Functional Theory Study

Alicia Brown, Varsha Jain and Neeraj Rai

Mississippi State University

In the past few years, research interest in biomass conversion to fuels and chemicals has increased signif-icantly with growing concern about the depletion of fossil fuels. A crucial element of biomass conversionis finding an effective means of catalytically upgrading these fuels to remove phenolic compounds, as fuelswith high concentrations of these compounds are characterized by low stability, low volatility, and highviscosity. Bimetallic catalytic surfaces are especially conducive for this process because synergistic in-teractions between the metal components allow for greater electron density, selectivity, and stability thanmonometallic surfaces. Further, the incorporation of non-metallic atoms such as phosphorous can enhancethe properties of the metals by altering the distribution of the charge between metals. In this study, weexamined the catalytic activity of the NiMoP bimetallic catalyst for the deoxygenation of phenolics usingthe density functional theory (DFT) method. In particular, we examined the bulk properties of the catalystand the adsorption of phenol on several Miller Index surfaces in order to identify the most likely deoxy-genation mechanism for each surface. On the 001 and 010 Miller Index surfaces in particular, we examinedthe hydrodeoxygenation (HDO) reaction mechanism in order to determine the selectivity of these surfacesfor the HDO reaction pathway. For future work, we will be examining the HDO reaction mechanism onadditional surfaces, experimenting with different molar ratios of the catalyst, and running nudged elasticband calculations in order to determine the activation energy barrier for each surface.

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#8

Machine Learning Feed Forward Network for Single Site Metal Cation Catalysts

Andrew Samstag, Steven Pellizzeri and Rachel B. Getman

Clemson University

In this work, we identify the electronic properties that predict catalytic activity for "single site" metal cationcatalysts, analogous to how the metal d-band can be used to predict catalytic activity for extended transitionmetal catalysts. Specifically, we identify the electronic properties of transition metal cation catalysts thatare well-correlated to the binding energy of an oxygen adsorbate, which is often used as a descriptor ofactivity for catalytic oxidations. To accomplish this objective, we catalogued the electronic properties ofthe metal cation catalysts, such as the energies of the highest occupied (HOMO) and lowest unoccupied(LUMO) molecular orbitals, and we input them into a machine learning neural network. Using PyBrain,a modular machine learning library for Python, we created an artificial neural network that generates analgorithm to predict the binding energy of an oxygen adsorbate on single site metal cation catalysts basedon the catalogued electronic properties. To improve our predictive model, we applied a perturbation methodto calculate the normalized sensitivity coefficients of the input variables and eliminate electronic propertiesthat do not statistically reduce the predictive error. The results of the perturbation method indicate that theenergy and occupancy of the d-orbital, spin, Pauling electronegativity, highest occupied molecular orbital(HOMO) energy, and lowest unoccupied molecular orbital (LUMO) energy of the catalyst are key electronicproperties in the description of the oxygen binding energy on the metal cation catalysts that we simulated.

17

#9

Mechanocatalytic Hydrogenolysis and Hydrolysis of Diphenyl Ether

Andrew Tricker, Rohan Kadambi, Alex Brittain and Carsten Sievers

Georgia Tech University

As the largest source of natural aromatics, lignin offers a renewable alternative for producing chemicals thatare currently made from petroleum, but it is currently mostly utilized as a low value fuel in recovery boilersat pulp and paper plants. One of the three main biopolymers in lignocellulose, lignin provides rigidity andresilience to plant cell walls, but is recalcitrant to degradation, due to its random linkages, which makes theproduction of monomeric aromatics difficult. The most common methods for catalytic depolymerization arelimited by the solubility of lignin in common solvents and typically require harsh organic or super-criticalsolvents and high temperatures and pressures. Mechanocatalytic systems avoid these issues because theycan perform solid-solid reactions at nominally ambient conditions. In mechanocatalytic reactions, the re-quired energy is delivered via collisions, and the mechanical forces can cause structural or conformationalchanges in the material to alter reactivity, or produce hot spots, small pockets of extreme temperature andpressure that last fractions of a second, to drive the chemical reaction.

Previous work in our group demonstrated the effectiveness of mechanochemical depolymerization of organo-solv lignin with sodium hydroxide. While the lignin polymers are depolymerized from six monomer unitsto majority monomers and dimers within 30 minutes, sodium phenolate salts are produced, which requirefurther processing to recover the aromatic products. The use of solid catalysts would avoid the productionof salts and facilitate catalyst recovery.

Reactivity studies were conducted with diphenyl ether, a model compound representing the 4-O-5 linkage,with platinum on alumina catalyst in a humidified hydrogen atmosphere. The reactions were carried out ina vibratory ball mill modified to allow for gas flow through the reactor vessel. Studying the effectivenessof catalysts on model compounds allows for mechanistic insights without having to deal with the manyanalytical challenges of real lignin. The primary products were cyclohexanol, benzene, and cyclohexaneas characterized by GC/MS and quantified by GC/FID. Future work will focus on reactivity studies withdifferent catalysts and reactive environments to depolymerize lignin.

18

#10

Determination and Enhancement of the Synergistic Effects of ReOx-Pd/CeO2 for ImprovedDeoxydehydration of Organic Compounds

Elizabeth Barrow, Stephanie Sanchez and Jochen Lauterbach

University of South Carolina

ReOx-Pd/CeO2 is known to be effective for the hydrodeoxygenation of vicinal OH groups with reportedyields as high as 99% in the batch production of THF from 1,4-anhydroerythritol [1]. Unfortunately, in-creased Re loading above 2wt% decreases the catalytic activity monotonically. Various hypotheses havebeen reported in the literature for the decrease in activity of Rhenium doped oxides with increased loading.Some report that upon reaching a loading limit of ReOx on oxides, additional ReOx loading produces Bron-sted acid sites yet each ReOx remains isolated [2]. Others report that with coverages over 2wt% on CeO2,the ReOx species begin to crosslink forming Re-O-Re [3].

In this study, we employ Raman, Infrared Spectroscopy, and Temperature Programmed Reduction to explorethe effect of CeO2 source and ReOx loading on the acidity and surface structure of ReOx/CeO2. Pyridineadsorption is studied using DRIFTS, and in-situ reduction is studied with IR transmission. We further studythe effect of the use of a Pd promoter on the ReOx/CeO2 acidity. Upon understanding how the CeO2 surfaceresponds to increased ReOx loading, additional promoters can be studied to eventually increase ReOx load-ing without decreasing activity per atom.

References:1. Angew. Chem. Int. Ed. 2015, 54, 1897-19002. Journal of Molecular Catalysis, 76 (1992) 263-2853. ACS Catal. 2016, 6, 3213-3226

19

#11

Synthesis and Reactivity of Supported Pt Single Atoms and Small Clusters for CO Oxidation

Chun-Te Kuo, Yubing Lu, Xiwen Zhang and Ayman M. Karim

Virginia Polytechnic Institute and State University

The catalytic oxidation of CO on Pt catalysts has practical importance in automotive catalysis and also servesas a probe reaction for fundamental understanding of heterogeneous catalysis. In this study, Pt single-atoms,clusters and nanoparticles supported on MgAl2O4 were prepared by strong electrostatic adsorption (SEA) atconstant pH. The synthesis conditions and pretreatment conditions for achieving either single atoms or clus-ters will be presented. The catalysts were quantitatively characterized by in-situ diffuse reflectance infraredFourier transform spectroscopy (DRIFTS) with adsorbed-CO as probe molecule to provide information onadsorption strength and geometry. At present, supported Pt nanoparticles have been well studied for COoxidation, however the mechanism on small clusters and single atoms is still under debate. During CO oxi-dation, the surface of Pt nanoparticles is poisoned by a high coverage of CO and the reaction shows reactionorders of -1 in CO and 1 in O2 (rate = k[O2]1[CO]−1). Here, we report kinetic behavior of Pt single atomsand clusters present under the same reaction condition. Using in-situ DRIFTS, we will compare the moststable reaction intermediates on Pt single atoms and clusters and discuss the possible reaction mechanismsleading to the observed reaction orders.

20

#12

Semiconducting Layered Heterostructures for Photocatalytic Reduction of CO2

Debtanu Maiti, Johnnie Cairns, Venkat R. Bhethanabotla and John N. Kuhn

University of South Florida

Photocatalysis is being studied for several decades and still enjoys significant attention in the scientificresearch community. It presents a great opportunity for harvesting the abundant solar energy for watersplitting and CO2 reduction reactions [1,2]. In recent times, there has been significant efforts to reduce theatmospheric CO2, a prominent cause for global warming. Majority of the materials being investigated forsolar photocatalytic applications suffers from either poor rates or stability issues. Even titania (TiO2), oneof the best catalysts till date is active only under UV light, making it unsuitable for harvesting solar energy.The metal oxynitrides [3] can be a potential solution for this solar photoreduction of CO2. We have studiedsolid solutions of zinc oxide, aluminum nitride and gallium nitride to investigate their band gap tunability.Strain and vacancy defects are two well know phenomena that dominate solid solution material properties.We hereby probed the effect of strain and different vacancy concentrations towards band gap modulationvia density functional theory (DFT). Compositions of solid solutions were varied to identify appropriatecandidates for photocatalytic applications. Consistent trend of band gap variation was obtained with mate-rial composition variation. These materials are thus perfect platforms for material property engineering forvaried electronic and photocatalytic applications.

References:1. Li K, An X, Park KH, Khraisheh M, Tang J. A Critical Review of CO2 Photoconversion: Catalysts andReactors. Catalysis Today 2014, 224: 3-12.2. Izumi Y. Recent Advances in the Photocatalytic Conversion of Carbon Dioxide to Fuels with Water and/orHydrogen Using Solar Energy and Beyond. Coordination Chemistry Reviews 2013, 257(1): 171-186.3. Fuertes A., Metal Oxynitrides as Emerging Materials with Photocatalytic and Electronic Properties,Materials Horizons, 2015, 2, 453-461.

21

#13

An ATR-IR Study of CO Adsorption on Pt Supported Catalysts in Different Solvents

Eric Husmann and Ayman M. Karim

Virginia Polytechnic Institute and State University

Solvents have been shown to affect the activity and selectivity of heterogeneous catalysts. However, the rolesolvents play in affecting the reactivity is not well understood. One possible role is affecting the adsorptionof reactants on the surface of nanoparticles. To investigate this role, an attenuated total reflection-infraredspectroscopy (ATR-IR) cell was designed and optimized to study CO adsorption onto platinum supportedcatalysts in various solvents. We will present the cell design, effect of catalyst synthesis, and coating on theATR crystal, on the quality of adsorbed CO spectra. Spectra of CO adsorbed on Pt/Al2O3 were collectedin solvents with varying polarity, acidity and basicity and the effect on C-O vibrational frequency will bepresented and correlated with the solvent properties. Lastly, possible role of the solvents in affecting theC-O vibrational frequency and binding strength to Pt will be discussed.

22

#14

Kinetic Monte Carlo Simulation of Direct Propylene Epoxidation on Supported Gold Nanoparticles

Jingjing Ji 1, Zheng Lu 2, Yu Lei 2 and C. Heath Turner 1

1. Chemical and Biological Engineering, the University of Alabama2. Chemical and Materials Engineering, the University of Alabama

Propylene oxide is a key chemical intermediate for the production of a number of commodity chemicals,including polyol, propylene glycol, and glycol ethers. However, current industrial methods that producepropylene oxide from propylene (namely chlorohydrin and hydroperoxide processes) pose environmentalrisks because of the production of chlorinated or peroxycarboxylic waste. The direct propylene epoxidationreaction has been investigated experimentally in the past by several different groups, and gold-based cata-lysts tend to provide high selectivity for propylene oxide, but the conversion is relatively low. Models thatcan connect the atomistic catalytic details to the observed experimental data are desired, in order to identifynew catalyst structures and formulations. While electronic structure calculations have been used to quantifysome of the key reaction steps in the direct propylene epoxidation reaction, atomistic models for translatingthis information into more experimentally-relevant data are needed.

Here, kinetic Monte Carlo (KMC) simulations are used to bridge this gap in the modeling hierarchy. Rele-vant data from previous experiments and electronic structure calculations are used to parameterize a KMCmodel for predicting propylene oxide production from an Au/TiO2/SiO2 catalyst. Although the model isa simple two-dimensional representation of the actual catalyst surface, the basic catalyst features are pre-served (Ti concentration, Au loading, Au particle sizes), and the KMC results are benchmarked againstrelevant experimental data. The model connects the H2/O2-related reactions occurring on the Au sites withthe epoxidation step on the isolated Ti surface sites. In addition, the composition in the bulk gas phase is syn-chronized with the dynamic reaction events occurring on the surface. The KMC model is able to adequatelyreproduce the experimental trends with respect to temperature and different reactant partial pressures. How-ever, this is only achieved by considering the re-adsorption of trace amounts of the oxidant (H2O2) from thegas phase, versus merely assuming that desorbed species are immediately swept away in the gas stream.

23

#15

PdFe Bimetallic Catalysts for the Hydrodeoxygenation of P-Cresol

Jeremiah Lipp, Fahad Almalki and John R. Regalbuto

The University of South Carolina

Chemical fuels are valuable to society because of the way that they store a large amount of energy until itis needed. Liquid fuels are especially valuable because of their additional capability to flow (for example,through an internal combustion engine), making them ideal for transportation. For this reason liquid fu-els are the main source of energy for transportation. Most of these liquid fuels are currently refined frompetroleum. In 2016, 25.7 out of the total 27.9 quads of energy used for transportation in the United States(92%) was derived from petroleum [1]. Unfortunately, petroleum is a finite resource. It is therefore desirableto find other sources for liquid fuels.

One promising source for liquid fuels is biomass. Entire plants, for example agricultural waste or forestresidue, can be broken down into bio-oil by heating them in the absence of oxygen (a process called pyrol-ysis). The molecules that make up this bio-oil contain a large amount of oxygen, which lowers the amountof energy that is stored in the bio-oil and also makes it difficult for the bio-oil to flow. In order to upgradethe bio-oil into transportation fuel the oxygen must be removed (deoxygenation). The challenge is to breakthe carbon-oxygen bonds without breaking carbon-carbon bonds or hydrogenating the bio-oil.

This project aims to synthesize a PdFe bimetallic supported catalyst to selectively deoxygenate bio-oil inorder to upgrade it into transportation fuels. Dry impregnation has been used to prepare Fe2O3 nanoparticlessupported on silica. Strong electrostatic adsorption (SEA) will be used to deposit Pd onto the Fe2O3 (butnot the silica support). The catalysts will be reduced, characterized by XRD and STEM, and tested for theHDO of p-cresol (a model molecule for bio-oil). It is expected that the use of rational catalyst synthesis inthe form of SEA will result in small, well dispersed particles with high conversion and selectivity for HDO.

References:1. Lawrence Livermore National Laboratory. Estimated U.S. Energy Consumption in 2016: 97.3 quads.https://flowcharts.llnl.gov/content/assets/images/charts/Energy/Energy_2016_United-States.png (accessed July27, 2017).

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#16

Synthesis of Ruthenium Based Hollandite Catalyst for Ammonia Decomposition

Katie McCullough and Jochen Lauterbach

University of South Carolina

Hydrogen has great potential as an alternative fuel source for vehicles and fuel cells. It is an attractivemedium for the mobile conversion of chemical to electrical energy because it can delivery efficiencies be-tween 50-60% when used in fuel cells. Hydrogen also boasts an energy density of 120 MJ/kg, as comparedto gasoline’s 44 MJ/kg. However, the delivery and transportation of hydrogen to mobile locations provesdifficult due to the lack of infrastructure and the cost associated to either compress or liquefy hydrogen.Here we further explore the use of ammonia as a storage medium for hydrogen production. Ammonia iseasily liquefied and the infrastructure already exists due to its widespread use in the agricultural sector.

Previous work in our group found that ruthenium based catalyst with a KRu4O8 hollandite structure hadsuperior catalytic activity towards ammonia decomposition [1]. Hollandite is able to decompose ammoniaat lower temperatures than the typical nanoparticle ruthenium catalyst. Typical hollandite structures aresynthesized via either a solid solution heated to 1200◦C or by hydrothermal synthesis [2, 3]. Here, weshow that ruthenium hollandite can be formed on an alumina support via incipient wetness impregnation.Furthermore, we will discuss the mechanism through which hollandite formation occurs, as evidenced bySEM, XPS, TEM and XRD analysis. Additionally, we explore the synthesis of novel bimetallic rutheniumhollandite catalysts using a high throughput approach. Several metallic tunnel like structures have beensuccessfully synthesized and tested for ammonia decomposition in order to lower the cost of catalyst pro-ductions and to try to further decrease the operating temperature required to reach >90% conversion ofammonia.

References:1. Pyrz, William, Rohit Vijay, Jason Binz, Jochen Lauterbach, and Douglas J. Buttrey. Top Catal (2008)50:180-191.2. Feng, Qi, Hirofumi Kanoh, Yoshitaka Miyai, and Kenta Ooi. Chem. Mater. 1995, 7, 148-153.3. M.L Foo, Wei-Li Lee, T Siegrist, G Lawes, A.P Ramirez, N.P Ong, R.J Cava. Mater. Res. Bull. 39(2004) 1663-1670.

25

#17

Understanding Structural Influence on Multicarbon Formation in CO2 Electroreduction

Emily Marx, Siwen Wang and Hongliang Xin

Virginia Tech University

Nowadays, electrocatalysis plays a pivotal role for renewable technologies, such as energy capture/storageand greenhouse gas emission reduction. Electrochemical CO2 reduction has received considerable attentionbecause of its potential to utilize the abundant greenhouse gas in the Earth’s atmosphere, and the electric-ity from intermittent renewable sources, to yield fuels and chemicals that are traditionally derived frompetroleum. Cu is, arguably, the only known metal that produces appreciable amounts of hydrocarbons andoxygenates, although at high overpotentials ( 1.0 V) [1]. Various studies have shown that the surface struc-ture of Cu nanocatalysts has a dramatic effect on the selectivity toward multicarbon species (e.g., ethylene)[2, 3]. However, the carbon-carbon coupling mechanism and its structural influence remains elusive, whichlimits catalyst optimization.

In this poster, we will present our recent work on understanding C-C coupling reactions on Cu modelsurfaces of varying terminations using density functional theory calculations. Because the chemical reac-tivity of a metal site on a nanoparticle is highly dependent on its local chemical environment, the activ-ity/selectivity trend is likely a function of the size of nanoparticle [4]. By leveraging our recently developedorbitalwise coordination number descriptors, we will discuss the strategy for optimizing the local structureand metal composition of Cu nanocatalysts toward multicarbon formation in CO2 electroreduction.

References:1. Y. Hori, in Modern Aspects of Electrochemistry, edited by C. G. Vayenas, R. E. White, and M. E.Gamboa-Aldeco (Springer New York, 2008), pp. 89-189.2. Y. Li, H. Su, S. H. Chan, and Q. Sun, ACS Catal. 5, 6658 (2015).3. Y. Hori, I. Takahashi, O. Koga, and N. Hoshi, J. Mol. Catal. A Chem. 199, 39 (2003).4. O. A. Baturina, Q. Lu, M. A. Padilla, L. Xin, W. Li, A. Serov, K. Artyushkova, P. Atanassov, F. Xu, A.Epshteyn, T. Brintlinger, M. Schuette, and G. E. Collins, ACS Catal. 4, 3682 (2014).

26

#18

Combinatorial Study of Cu-Ag Based Ethylene Epoxidation Catalysts

Kathleen Mingle, John Welsh and Jochen Lauterbach

University of South Carolina

The catalytic epoxidation of ethylene to ethylene oxide (ETO) is an important process with worldwide pro-duction exceeding 20 MT/year. Commercially, ETO is formed over promoted silver (Ag) catalysts at 85%selectivity, meaning that a mere 1% increase in selectivity could translate to millions of dollars in annualsavings. Ag based catalysts are considered to be the unique ethylene epoxidation material despite evidencesuggesting that Cu can have superior epoxide selectivity to Ag alone. Additionally, Cu has yet to be in-corporated into industrial catalysts at all due to uncertainties regarding the oxidation state of the active Cuspecies and the possibility of phase segregation and catalyst deactivation under reaction conditions.

Previous experimental work has shown that selective Cu-Ag alloy epoxidation catalysts are in fact feasi-ble under certain conditions and that Cu stability and activity may be influenced by co-promoters. Here,we expand on this work by pairing design of experiments guided wet impregnation synthesis with high-throughput reactor tests to map Ag-Cu stability and selectivity over a range of catalyst formulations andoperating regimes. Various third and fourth elements including Cs, Re, Pd, Au, Ru, Sn, and Mn were addedto the base Ag-Cu formulation over a range of loadings and impregnation sequences. Reactant partial pres-sures and temperatures were investigated to elucidate the operational regime over which Ag-Cu catalystswere stable and selective. A comparison of these results to base Ag catalysts prepared in a similar mannerand tested under comparable conditions reveals the effects of Cu addition.

Catalysts containing up to 1% Cu showed no discernible deactivation throughout reaction studies. Theseresults, coupled with XPS results suggest that Cu oxides can be a component of active Cu-Ag catalysts.However, reaction kinetics point toward higher rates of ethylene oxide formation at higher ethylene feedfractions for Cu-Ag catalysts when compared to catalysts containing Ag only. This may suggest that whilethe presence of Cu oxides does not lead to total catalyst deactivation, the more active species is metallic Cuas evidenced by higher activities in a more reducing environment. Additionally, the promotional effects ofclassic ethylene epoxide promoters such as Re and Cs were found to deviate from what was expected for Agonly catalysts upon the addition of Cu.

27

#19

Elevated Temperature Photocatalytic Production of Hydrocarbons from CO2 and H2O

Morghan Parker, Samiksha Poudyal and Siris Laursen

University of Tennessee

Artificial photosynthetic production of hydrocarbons and oxygenates from CO2, H2O, and light is a promis-ing route to truly sustainable fuels and chemical building blocks for society. However, despite many efforts,a complete and predictive fundamental understanding of the chemical and physical processes that allowsfor controlled degrees of CO2 reduction, hydrogenation, and carbon-carbon coupling are still lacking. Atambient temperature and in condensed aqueous phase conditions, the photocatalytic production of CH4 andhigher hydrocarbons are significantly limited and often fail to compete effectively with unselective H2 evo-lution. Breaking this mold, our studies aim to illustrate the use of elevated temperature (100-500◦C), gasphase photocatalytic systems to gain mechanistic information such that photocatalysts and reaction environ-ments can be rationally designed to produce higher hydrocarbons and oxygenates with high hydrogen andquantum efficiency. Combined quantum chemical surface reaction modeling and experimental studies haveprovided significant insight into the bulk electronic and surface chemical properties of photocatalysts thatdictate product selectivity between H2, CO, and CH4 in CO2 reduction by H2O. Specifically, our studieshave clarified the role of surface chemistry in driving C-O cleavage; different oxidation states of surfacebound atomic hydrogen in the hydrogenation, and hydrogenation vs. carbon-carbon coupling rate in theproduction of hydrocarbons.

28

#20

Hierarchical MFI-Zeolite Catalysts for Glycerol Acetylation

Qandeel Almas, Carsten Sievers and Christopher W. Jones

Georgia institute of Technology

Glycerol is produced in large quantities (10% by wt. of the total biodiesel product) as the main by-productin the transesterification of triglycerides with methanol. The low uptake of glycerol by industries has jeop-ardized the economic feasibility of biodiesel as a renewable fuel. To overcome this issue, the transformationof glycerol into valuable chemicals and biodiesel additives is one of the most promising solutions. Theacetylation of glycerol with acetic acid (or acetic anhydride) yields monoacetin (MAG), diacetin (DAG)and triacetin (TAG); the first two compounds have applications in cryogenics and serve as raw materials forbiodegradable polymers, whereas triacetin is a valuable petrol fuel additive.

We investigated the relative stability of the microporous and hierarchical ZSM-5 zeolites in the acetylationof glycerol with acetic acid in liquid phase batch conditions. The microporous ZSM-5 was synthesized via ahydrothermal synthesis route. The hierarchical pore structure in the ZSM-5 was created by two techniques,(i) the alkaline desilication of a microporous ZSM-5, and (ii) a hydrothermal synthesis using an amphiphilicorganosilane surfactant as the structure-directing agent. The chemical and structural properties of the freshand spent catalyst were studied and compared by X-ray diffraction (XRD), nitrogen adsorption-desorptionisotherms, pyridine adsorption followed by Fourier transform infrared spectroscopy (Py-IR), scanning elec-tron microscopy (SEM) and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spec-troscopy. All three zeolites demonstrated similar conversions of glycerol. A characterization of the spentzeolites showed that the properties of the bulk zeolite were significantly affected by the acidic medium ofthe reaction.

29

#21

Tuning the Selective Hydrogen Combustion Properties of Mn-based Redox Catalysts

Ryan B Dudek, Yunfei Gao, Junshe Zhang and Fanxing Li

North Carolina State University

Increased availability of light alkanes from shale gas has sparked interest in producing critically importantolefins (e.g. ethylene, propylene) from the corresponding alkane feedstocks. Steam cracking of ethane andpropane are promising processes for producing olefins from corresponding paraffins, but these processesare characterized by intensive carbon emissions and thermodynamically limited yields. Oxidative dehydro-genation (ODH) operated in a cyclic redox mode provides an alternative option for olefin production withincreased energy efficiency and facilitated CO2 capture. Redox mode ODH employs a metal oxide-based"redox catalyst" which donates its active lattice oxygen towards the oxidation of the H2 co-produced witholefins; when done selectively, this selective hydrogen combustion (SHC) drives greater-than-equilibriumolefin yields and provides in-situ heat generation to the process.

We carried out a systematic investigation of manganese-containing mixed metal oxide "redox catalysts" withthe goal of discovering inexpensive and non-toxic materials capable of performing SHC under reaction con-ditions. In particular, we focused on establishing tunable SHC behavior in these redox catalysts by choosingdifferent alkaline earth cations and forming different structure types. The effects of promoting and dopingthe mixed metal oxides with other metals and using different operating temperatures were also comprehen-sively evaluated.

Mixed metal oxides containing Mn are shown to be effective materials for selective hydrogen combustion.SHC properties can be tuned by changing (a) the bulk metal oxide; (b) type and weight loading of promotersand dopants; and (c) operating temperature. At optimal conditions, H2 combustion selectivity of 95% orgreater can be achieved with H2 conversions of 10% or more over the temperature range from 550◦C to850◦C; five materials were found to exhibit >97% selectivity at 650◦C. Addition of metal dopants is shownto effectively tighten the SHC temperature range by inhibiting carbon oxidation by the mixed metal oxides.The amount of hydrogen combusted can be controlled for specific process considerations by varying gascontact time and operating temperature. Redox catalyst performance for SHC is shown to be stable overmany redox cycles. The materials tested are suitable for application in a cyclic redox process for the moreenergy-efficient production of ethylene and propylene.

30

#22

Mg6MnO8 Based Redox Catalysts for Oxidative Dehydrogenation of Ethane via a Cyclic RedoxScheme

Seif M. Yusuf, Luke M. Neal and Fanxing Li

North Carolina State University

Oxidative dehydrogenation (ODH) of ethane represents a promising alternative to steam cracking for theproduction of ethylene that can result in a higher ethane conversion, lower energy consumption and lowerCO2/NOx emissions. Conventional ODH, however, suffers from challenges in process safety, controllability,and high capital cost due to the needs to co-feed gaseous oxygen with ethane. In chemical looping ODH(CL-ODH), ethane is partially oxidized by active lattice oxygen in a redox catalyst, producing ethylene andwater. The reduced redox catalyst is subsequently re-oxidized with air in a separate reactor prior to the ini-tiation of another redox cycle. Such a cyclic redox scheme eliminates the needs for cryogenic air separationas well as oxygen co-feeding. In this process, it is crucial to suppress deep oxidation without sacrificingethane conversion. This study focuses on testing and characterization of Mg6MnO8 based redox catalystsfor the CL-ODH of ethane.

Mg6MnO8 based redox catalysts were able to improve single pass ethane conversion compared to thermalcracking. When promoted with sodium tungstate, the redox catalyst was able to increase the ethylene singlepass yield by 38.9% when compared to thermal cracking. Ethane TPR suggests that the reaction pathway forthe sodium tungstate promoted redox catalyst is parallel thermal cracking of ethane and selective combus-tion of hydrogen. X-ray Photoelectron Spectroscopy (XPS) and Low Energy Ion Scattering (LEIS) analysesindicate that the sodium tungstate promoter reduces the average manganese oxidation state and suppressesthe amount of surface manganese. These results indicate that the sodium tungstate promoter suppresses theamount of surface Mn4+ which is responsible for the non-selective electrophilic oxygen species.

Design and optimization of effective redox catalysts are crucial for successful development of such a promis-ing process. The current study not only reports a highly effective redox catalyst, but also reveal the underly-ing mechanism for such a redox catalyst. The findings can be significant for further improvements of redoxcatalyst performances in CL-ODH.

31

#23

Tri-Reforming of Methane over NiCe@SiO2 Yolk-Shell Nanotube Catalysts

Sunkyu Kim, Bradie S. Crandall, Erdem Sasmaz and Jochen Lauterbach

University of South Carolina

Tri-reforming of methane is a viable option for utilizing fossil fuel emissions directly from the stack witha desirable H2/CO product ratio. The process involves synergistic combination of three reactions; dry andsteam reforming, and partial oxidation of methane. Typically, Ni-based catalysts are shown to be effectivefor tri-reforming with CH4 and CO2 conversions reaching up to 90% and 70% at 750◦C, respectively. Theactivity of Ni catalysts can be improved at reaction temperatures lower than 750◦C by developing materialsthat demonstrate high resistance to oxidation and coke formation. To achieve this, one needs to understandthe interaction between Ni and support, and modify it to stabilize Ni particles on the support.

An effective method to synthesize highly active Ni particles is to develop bimetallic particles encapsulatedby a stable support. In this study, NiCe@SiO2 catalyst with a yolk-shell structure was prepared and appliedto the tri-reforming of methane. The synthesized catalysts were characterized by means of XRD, BET, H2-TPR, TEM, and ICP. Their catalytic performances were measured in terms of conversion and yield. Theresults showed that CeO2 increased active oxygen species with reversible valence change, and the silicashell distributed and stabilized Ni particles. In addition, it was found that the synthesis parameters played acrucial role in the oxidation of Ni during the reaction, which could essentially enhance coke formation andcatalyst deactivation.

32

#24

Large-Scale Nonadiabatic Molecular Dynamics Enabled by Machine Learning

Jiamin Wang 1, Liang Yu 1, Hirohito Ogasawara 2, Frank Abild-Pedersen 3 and Hongliang Xin 1

1. Department of Chemical Engineering, Virginia Tech, VA 24060, USA2. Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill

Road, Menlo Park, CA 94025, USA3. SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, 2575

Sand Hill Road, Menlo Park, CA 94025, USA.

Transferring energy from solid surfaces to chemical bonds of adsorbed species is a fundamental process inheterogeneous catalysis. To a great extent, the dynamics of molecule-surface interactions driven by ther-mal energy, i.e., heat, can be well described within the framework of the Born-Oppenheimer approximationwhere the electronic and nuclear motions can be treated separately. New reaction channels often open upin response to electronic excitations via surface-mediated energy transfer [1]. In this process, the energeticelectrons or holes can scatter into surface species and heat up vibrational modes of adsorbates. This processinvolves not only the electronic ground state but also the excited state, and it is nonadiabatic with respect tothe nuclear motions.

The nonadiabatic energy transfer on metal surfaces can be modeled using the ground-state potential en-ergy surfaces and the nonadiabacity is taken into account with electronic friction contributions in Langevindynamics [2]. In essence, the electronic friction via partial populating and depopulating of the adsorbateground state right above the Fermi level is governing the energy transfer. However, it is extremely timeconsuming to compute the electron-phonon coupling strength with accurate first-principles methods, partic-ularly for large systems. We are presenting a machine-learning-enabled molecular dynamics approach thatuses predicted forces and electronic friction coefficients by "learning from ab initio data". Machine learningalgorithms, such as the artificial neural networks, can use past trajectories as training datasets for fast andaccurate prediction of forces and electronic friction coefficients, thus allows us to perform statistical analy-sis of many trajectories. In this poster presentation, we will use CO oxidation on Ru(0001) as a benchmarksystem of the approach.

References:1. Bonn, M. et al. Phonon-Versus Electron-Mediated Desorption and Oxidation of CO on Ru(0001). Science285, 1042-1045 (1999).2. Head-Gordon, M. and Tully, J. C. Molecular Dynamics with Electronic Frictions. J. Chem. Phys. 103,10137-10145 (1995).

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#25

Theoretical Investigation of the Pt Catalyzed Hydrodeoxygenation of Succinic Acid to1,4-Butanediol

Wenqiang Yang, Muhammad Osman Mamun and Andreas Heyden

University of South Carolina

The reaction mechanism of the hydrodeoxygenation (HDO) of succinic acid (SUCC) to 1,4-Butanediol(BDO) has been investigated over a Pt (111) catalyst surface model by a combination of plane-wave densityfunctional theory (DFT) calculations and mean-field microkinetic modeling. Catalytic pathways of the con-version of SUCC to BDO in gas phase with and without β -C dehydrogenation steps have been considered.Overall, 187 surface intermediates and more than 600 elementary reaction steps are involved in the reactionpathways. Using DFT and dimer calculations, we found the stable surface states of the intermediates and thetransition states of 158 elementary reactions steps. Based on Brφnsted-Evans-Polanyi (BEP) relationship,we predicted the free energies of the transition states of the remaining elementary reaction steps. For C-Hbond dissociation steps, the mean absolute error (MAE) of the BEP prediction is 0.16 eV. For C-O and O-Hbond dissociation steps, the BEP predicted MAEs are 0.13 eV and 0.14 eV, respectively. Using calculatedand BEP predicted energies, we built a mean-field microkinetic model to study the reaction kinetics for theHDO conversion of SUCC to BDO at different temperatures, ranging from 373 K to 573 K. Rate controllingsteps, key surface intermediates, and turnover frequency were determined. However, due to a very smallnumber of free sites available for catalysis, Pt (111) is not active towards the HDO conversion of SUCC toBDO, which demonstrating that the Pt (111) surface may not be the active site for BDO production duringthe SUCC hydrodeoxygenation process.

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#26

Alkali Promoted Lanthanum Strontium Ferrite for Oxidative Dehydrogenation of Ethane Under aCyclic Redox Scheme

Yunfei Gao, Luke M. Neal and Fanxing Li

NC State University

Chemical looping oxidative dehydrogenation (CL-ODH) of ethane utilizes a transition metal oxide basedoxygen carrier, also known as redox catalyst, to convert ethane into ethylene under an autothermal cyclicredox scheme. Unlike typical ODH, CL-ODH eliminates the needs for gaseous oxygen, rendering a saferand more efficient process. Compared to conventional steam cracking, CL-ODH has the potential to reducecarbon dioxide/nitrous oxide emissions by as high as 84%. The current study investigates alkali metal (Li,Na or K) promoted lanthanum strontium ferrite (LaSrFe) redox catalyst for CL-ODH. While LaSrFe withoutalkali promoter exhibit low ethylene selectivity, addition of alkali leads to high selectivity/yield and goodregenerability. Up to 61% ethane conversion and 90% ethylene selectivity are achieved. Further characteri-zation indicates that the surface of the redox catalysts is enriched with alkali cation. It is also determined theLaSrFe phase contributes to oxygen storage and donation whereas activity and selectivity of the redox cata-lysts are modified by the alkali promoter: while oxygen for the CL-ODH reaction is supplied from the latticeof the LaSrFe phase, the enrichment of alkali cation on the surface inhibits oxygen anion diffusion from thebulk and its subsequent evolution into electrophilic oxygen species on the surface. The non-selective natureof the surface oxygen species and the inhibition effects of alkali promoter on oxygen anion diffusion arefurther confirmed by pulse experiments. It is therefore determined that alkali promoted LaSrFe is an effec-tive redox catalyst for ethane ODH in absence of gaseous oxygen. Moreover, the selectivity of the redoxcatalysts can be enhanced by the alkali metal oxide promoters.

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#27

SO2 poisoning of Cu-SSZ-13 for NH3-SCR: Mechanistic Study and Kinetic Model Development

Yasser Jangjou 1, Di Wang 2 Ashok Kumar 2 Junhui Li 2 and William S. Epling 1

1. Department of Chemical Engineering, University of Virginia, Charlottesville, VA 22904 (USA)2. Cummins Inc., Catalyst Technology, Columbus, Indiana 47201 (USA)

Copper ion-exchanged small pore zeolite with a chabazite structure i.e. Cu-SSZ-13 has shown superioractivity and stability for NH3-SCR applications. However, in real-world conditions, Cu-SSZ-13 is proneto sulfur poisoning. Specifically, SOx (SO2 and SO3) inhibits low-temperature (< 350◦C) SCR activity ofsuch catalyst. Despite previous studies on sulfur poisoning of Cu-CHA catalyst, the poisoning mechanismis yet to be fully understood. In this study, the low-temperature SO2 poisoning mechanism of Cu-SSZ-13was studied with respect to the two main Cu active centers, i.e. Z2Cu and ZCuOH. Then, a detailed NH3-SCR kinetic model was developed to capture the behaviour of fresh, sulfated and regenerated (de-sulfated)Cu-SSZ-13. By varying Si:Al, two model catalysts were prepared with an opposite distribution of Z2Cuand ZCuOH as confirmed/characterized using inductively coupled plasma optical emission spectroscopy(ICP-OES), H2 temperature programmed reduction (H2-TPR) and diffuse reflectance infrared Fourier trans-form spectroscopy (DRIFTS). Moreover, temperature programmed desorption (TPD) and in-situ DRIFTSexperiments were utilized to study adsorption and desorption dynamics of S species on different active sites.DeNOx activity of fresh, sulfated and de-sulfated samples were also compared. The results show that theZ2Cu and ZCuOH respond differently to sulfur poisoning. Depending on which site S is being adsorbed on,the nature of S intermediates can be different i.e. either be present as ammonium sulfate (with its TPD fea-ture at 380◦C) or copper bisulfite (with its TPD feature decomposes at ∼580◦C). Therefore, SO2 poisoningand deSOx follow different routes on Z2Cu versus ZCuOH. Applying experimental findings, a mechanismwas assumed and kinetic model was developed based on that. The reaction scheme and governing equationsfor gas-phase and surface concentrations and temperatures were defined and solved using GT-ISE v2017software. The developed kinetic model precisely predicts the experimental behaviour of the fresh, sulfatedand de-sulfated catalyst observed during experiments.

36

#28

A Bayesian-Learned Newns-Anderson Model for Understanding Hydrogen Evolution on Metals

Zheng Li, Wei Shan Chin, Siwen Wang, Shih-Han Wang and Hongliang Xin

Virginia Polytechnic Institute and State University

Hydrogen evolution is one of the most studied electrochemical reactions. It is a desired cathode reaction inwater electrolysis and the competing side reaction that has to be suppressed in CO2 reduction and N2 reduc-tion. In acidic aqueous solutions, the hydrogen evolution reaction (HER) proceeds through three elementarysteps, starting with the proton discharge (Volmer-reaction) and followed by either the electrodesorption step(Heyrovsky reaction), or the *H recombination step (Tafel reaction). The ‘volcano‘ relationship of HERactivity across metal surfaces provides a straightforward and intuitive explanation for experimental results,while the detailed electron-transfer mechanism and its governing factors remain elusive, which casts doubtsinto the linear free energy approach for understanding activity trends of electrocatalytic reactions [1].

Recently, we have developed a Bayesian-Learned model Hamiltonian approach inspired by previous work[2] for understanding charge-transfer reactions on metal surfaces. Basically, we derive interaction param-eters in the Hamiltonian based on evidence, i.e., ab initio electronic and adsorption properties. In contrastto deterministic methods [2], the Bayesian approach with the Markov Chain Monte Carlo (MCMC) sam-pling method provides a natural framework for generating probabilistic estimates of latent variable, whileaccounting for uncertainties and incorporating prior knowledge if available. By employing the ‘big data’from ab initio simulations, we are mapping out reactivity properties of transition and noble metals towardhydrogen evolution; and most importantly, the model Hamiltonian approach allows us to pinpoint the gov-erning electronic factors in energetics of charge-transfer activated complexes with implicit consideration ofadsorbate-solvent interactions.

References:1. Zeradjanin, A. R.; Grote, J.-P.; Polymeros, G.; Mayrhofer, K. J. J. Electroanalysis 2016, 28 (10), 2256-2269.2. Santos, E.; Quaino, P.; Schmickler, W. Phys. Chem. Chem. Phys. 2012, 14 (32), 11224-11233.

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#29

Dual-Phase Co-Ionic Membranes by Solid-State Reactive Sintering Method for Catalysts Supporter

Zeyu Zhao, Shenglong Mu, Dong Jiang and Jianhua Tong

Clemson University

The protonic ceramics allow for the construction of low temperatures (300-600◦C) energy devices such asprotonic ceramic fuel cells, electrolyzers, and electrocatalytic membrane reactors. To well control the par-tial conductivities of protons and oxygen ions in protonic ceramics can in-suit provide or remove chargedspecies (proton and oxygen ions) to from catalytic reaction. For example, to simultaneously provide fourprotons and remove one oxygen ion to and from carbon dioxide molecule can a methanol molecule. There-fore, the fabrication of dense electrolyte membrane with controllable proton and oxygen ion conductivityis very meaning work. Furthermore, the co-ionic conducting structure used for electrode can provide morereactive surface for loading catalysts in the cathode side. However, the prototypical proton conducting ox-ides of BaCe0.7Zr0.1Y0.1Yb0.1O3−δ (BCZYYb), BaZr1−xYxO3−δ (BZY), and BaCe1−x−yZrxYyO3−δ usuallyshow poor co-ionic conductivity. Therefore, the co-ionic materials should be developed for improving theperformance of protonic ceramic energy devices. Furthermore, the recent work to use protonic ceramicmembrane reactors for methane dehydroaromatization to benzene also demonstrated that the proper amountof oxide-ion conductivity could burn carbon and improve the reaction stability. Therefore, to fabricate co-ionic conducting (proton and oxide-ion) dense membranes are urgently needed for both PCFCs, protonicceramic electrolysis, and protonic membrane reactors.

Dual-phase co-ionic conducting membranes are commonly prepared by mixing an oxide-ion conducting ox-ide and a proton conductor, which usually resulted in poor mixing and further long-term solid state reactionto achieve thermodynamic equilibrium. To overcome this weakness, solid-state reactive sintering (SSRS)method was utilized for fabricating dual-phase co-ionic conducting membranes. SSRS is a one-pot sim-ple preparation method, ensuring excellent mixing of different components. Finally, nanoscale dual-phasetriple-conducting materials were obtained.

In this work, we composited proton conducting oxide of BaCe0.5Zr0.4Y0.1O3−δ (BCZY) and oxide-ion con-ducting oxides of Ce0.5Y0.5O2 (YCO) to form co-ionic conducting material system with different phaseratios and utilized SSRS method to get very simple preparation process with high quality.

38

Oral Presentation Abstracts

Approaching the 150◦C Challenge with Passive Trapping Materials and Highly Active OxidationCatalysts

Andrew J. Binder 1, Eleni Kyriakidou 2, Todd J. Toops 1 and James E. Parks II 1

1. Oak Ridge National Laboratory2. SUNY at Buffalo

Here we present the analysis of HC-trapping/DOC combined system in LTC-D protocol simulated exhaustconditions. The catalysts used for this study include a Pd/ZSM-5 trapping material and a mixed-bed ofcore-shell SiO2@ZrO2 carrying either Pd or Pt catalyst (i.e. Pd/[SiO2@ZrO2] or Pt/[SiO2@ZrO2]). Re-sults indicate that the addition of Pd/ZSM-5 hydrocarbon trapping material can greatly increase the effec-tive activity of the downstream degreened DOC catalyst for both CO and THC conversion leading to 90%conversion of CO and THC over the total system at 135◦C and 163◦C, respectively. Even after repeatedsulfation/desulfation procedures and 50 hour aging at 800◦C the trap/catalyst system continues to show ap-preciable activity with T90 values of 175◦C (CO) and 230◦C (THC). This study demonstrates the both theeffectiveness of hydrocarbon trapping as a way to boost overall conversion and the need for highly stabletrapping materials in order to accomplish the 150◦C challenge after significant aging.

39

Synergy of Photo-Excitation and Surface Catalysis over Ceria-Based Materials for EnhancedPhotocatalysis

Dong Jiang 1, Wenzhong Wang 2 and Jianhua Tong 1

1. Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina29634, USA

2. Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050, PR China

Semiconductor photocatalysis has attracted worldwide attention for its promising potentials in energy andenvironmental uses, such as artificial photosynthesis and environmental purification. Essentially, photocatal-ysis is the integration of photoexcitation, which involves light harvesting as well as charge carriers output,and surface catalysis, mainly concerning the utilization of photoinduced electrons and holes. In order toachieve ideal solar energy conversion, above two sequential steps must be guaranteed concurrently. How-ever, currently employed strategies for enhanced performance usually focus on one-sided discussion.

Herein, integrated inspection of various elementary steps in photocatalysis is proposed, and the synergy ofphoto-excitation and surface catalysis are in depth understood over ceria-based systems, involving surfaceplasmon resonance, crystal facet engineering and surface hydrogenation. (1) Au NPs with various loadingamounts and sizes were attached to CeO2 nanorods by photodeposition. The dual roles which Au played inphoto-excitation and surface catalysis were carefully studied during propylene oxidation. Photo-excitationand surface catalysis present opposite dependence on Au NP size and codetermine the final photocatalyticperformance. (2) CeO2 nanocubes and nanorods with different facet exposure were prepared. Three ceriananocrystals presented complex reactivity priorities in various photocatalytic processes, including VOCsoxidation, O2 evolution and ·OH generation. Careful studies unveiled the important roles of surface defectstructures in photo-excitation and surface catalysis steps. The competition among different surface factorsdetermined the photocatalytic activity. (3) Gray CeO2 was prepared by treating pristine ceria in H2/Ar,presenting surface plasma resonance (SPR) like visible-light absorption. Hydrogenation induced abundantoxygen vacancies inside both the bulk lattice and the surface layer. Gray CeO2 presented much enhancedperformance as well as improved water resistance in photocatalytic oxidation of gaseous hydrocarbons.Careful studies unveiled the important roles which bulk and surface V2 played in photo-excitation andsurface catalysis steps.

40

Promoted Perovskites for Methane Partial Oxidation in Absences of Gaseous Oxidants

Luke M. Neal, Arya Shafiefarhood and Fanxing Li

NC State University

Reforming of methane to syngas is an important but energy intensive step in the synthesis of chemicals andliquid fuels from natural gas. Steam reforming does not give an ideal H2 to CO ratio for liquid fuel or chem-ical synthesis, and conventional methane partial oxidation (POx) approaches require costly air separation.Chemical looping reforming (CLR), which partially oxidizes methane into H2 and CO in the absence ofsteam or gaseous oxygen, offers a simpler and potentially more efficient route for syngas generation. Thisis achieved by cyclic removal and replenishment of active lattice oxygen in oxygen carrier particles (alsoknown as redox catalysts). Selecting a redox catalyst particle with high selectivity and facile oxygen trans-port is very important for CLR. Several redox catalysts have been reported in literature, but their activitiestoward methane POx are often limited due to slow internal oxygen transport and/or low oxygen capacity.Moreover, syngas selectivity is often low, as metal oxide surface species that promote methane activationtend to be non-selective. To address these limitations, we investigated the effects of compositing with singlemetal oxides as well as promoting catalytic surface activity for a number of mixed-metal-oxide based redoxcatalysts. Our findings indicate that surface promotion can lower the onset temperature of methane POx byas much as 300◦C while achieving >90% syngas selectivity.

While the dynamic nature of the system makes mechanistic studies challenging, understanding the mecha-nism is important to aid rational catalyst design. We report TGA-MS and pulse reaction and isotope studiesindicating that the selectivity of the redox catalysts is related to the relative rates of lattice oxygen (O2−)conduction to the surface vs surface oxygen removal by the gas-solids reactions. This is particularly thecase at the early stage of the reaction. Surface promotion can increase the oxygen removal rate from thesurface, thereby changing the type oxygen species present on the surface. This increase in oxygen removalis caused by the enhancement of surface methane activation. It is also shown that the rate of bulk latticeoxygen diffusion to the surface can be notably affected by surface promotion of the redox catalysts. Thisresults from the change in driving force for O2− conduction.

41

Sulfur Interactions with Pd and Pt Catalysts: Precious Metal Crystallite Size Dependence

Monique Shauntá Wilburn 1,2 and William S. Epling 2

1. University of Houston2. University of Virginia

Natural gas, which primarily consists of methane, is commonly viewed as a lower emission producing fuelin comparison to gasoline and diesel. Methane, which is not combusted in the engine, needs to be miti-gated and can be combusted over an oxidation catalyst placed in the exhaust stream. Natural gas vehicleexhaust temperatures can be as low as 300◦C making complete conversion challenging. The exhaust canalso contain sulfur, a poison to many oxidation catalysts, resulting in catalyst deactivation and reducing theextent of methane conversion. Researchers found that alumina-supported bimetallic Pt/Pd catalysts resultedin higher activity with time on stream in comparison to monometallic Pt and Pd catalysts. This improvementpersisted when exposed to water, although the authors concluded that the Pt-containing catalysts sinteredwhen exposed to steam at high temperature. However, the relationship between the sulfur poisoning impactand particle size was not studied.

The presentation associated with this work will focus on what species formed during Pt, Pt/Pd, and Pdcatalyst exposure to SO2 and their stability as a function of temperature. Initial experiments demonstratedthat in order to understand why sulfur release characteristics varied with precious metal (PM) particle size,it was imperative that the Pd:Pt mole ratio contribution be decoupled. For this reason, SO2 adsorption andtemperature-programmed desorption (TPD) studies, specific to particle size, were performed on catalystswith the same Pd:Pt mole ratios. Particle sizes were determined using CO pulse-injection chemisorption.At 150◦C, all samples formed aluminum surface sulfite species as well as physisorbed and chemisorbedmolecular SO2 on the aluminum surface. In contrast to Pt, the large particle size Pd catalysts were capable ofoxidizing molecular SO2 species to form aluminum surface sulfite species and subsequently form aluminumsurface sulfates even at 150◦C. Failure to form sulfates at lower temperatures resulted in large amounts ofSO2 being released in the low-temperature range of the TPD due to decomposition of surface sulfite species.This difference resulted in different relative amounts of low versus high temperature desorbing species. Byunderstanding how particle size influences sulfur interactions, catalysts can be better designed for longevityon stream, even in the presence of sulfur.

42

Controlling Reaction Selectivity through the Surface Termination of Perovskite Catalysts

Felipe Polo-Garzon 1, Shi-Ze Yang 2, Victor Fung 3, Guo Shiou Foo 1, Elizabeth E. Bicke 4, Matthew F.Chisholm 2, De-en Jiang 3 and Zili Wu 1∗

1. Chemical Sciences Division and Center for Nanophase Materials Sciences, Oak Ridge NationalLaboratory, TN, United States

2. Materials Science and Technology Division, Oak Ridge National Laboratory, TN, United States3. Department of Chemistry, University of California. Riverside, CA, United States

4. Department of Chemical Engineering, Tennessee Technological University. Cookeville, TN, UnitedStates

Although perovskites have been widely used in catalysis, tuning of their surface termination to control re-action selectivity has not been well established. In the past five decades, researchers have unsuccessfullyattempted to relate catalytic properties of bulk mixed oxides to bulk properties of the crystal structure, suchas the short metal-oxygen bond. At the catalytic "stage", the surface of a complex oxide can be differentfrom the bulk in both composition and structure. In this work, we show for the first time how the surfacetermination of perovskites, using SrTiO3 (STO) as an example, can be controlled to tune the catalytic se-lectivity in a wide range. The surface termination of STO was tuned via thermal pretreatment and chemicaletching. The obtained surface terminations were found to impact the catalytic acid/base properties using theconversion of 2-propanol as a probe reaction.

The surface of pretreated STO was characterized via multiple surface sensitive techniques, such as, lowenergy ion scattering (LEIS), methanol adsorption followed by FTIR, high-angle annular dark-field scanningtransmission electron microscopy (HAADF-STEM) and adsorption microcalorimetry. Heat treatment above500◦C under oxygen revealed Sr-enrichment of the surface and chemical etching with HNO3 revealed singleand double-layer Ti-enrichment of the surface. A cooperative effect between acid and base sites is shown bya non-linear correlation between the rate of dehydrogenation/dehydration and the concentration of surfaceSr/Ti. A wide range of selectivities toward propene or acetone was accessed after proper conditioning ofSTO; which is otherwise inaccessible using single metal oxides, SrO and TiO2. DFT calculations on Srand Ti-terminated surfaces of STO explained the observed high selectivity toward propene for Ti-terminatedsurfaces and low selectivity for Sr-terminated surfaces. Similar catalytic tunability is also observed onBaZrO2, thus highlighting the generality of the findings of this study.

43

Computationally-Driven Design of Cation-Based Catalysts for Ethene Conversions

Steven Pellizzer 1, Pere Miró 2, Varinia Bernales 3, Melissa Barona 2, Peilin Liao 2,4, Laura Gagliardi 3,Randall Q. Snurr 2 and Rachel B. Getman 1∗

1. Chemical and Biomolecular Engineering, Clemson University, Clemson, SC 29634, USA2. Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL 60208,

USA3. Department of Chemistry, Supercomputing Institute, and Chemical Theory Center, University of

Minnesota, Minneapolis, Minnesota 55455, USA4. School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907, United States

One of the largest challenges in catalysis research is finding novel catalysts that are active and selective forthe conversion of light hydrocarbons from shale gas into liquid products. Currently, converting natural gasinto liquid fuels is inefficient due to it requiring the preprocessing of natural gas into syngas through steamreforming, therefore to fully utilize shale gas developing technologies are needed that convert natural gasdirectly into liquid fuels. Our group has focused on single-site transition metal cation catalysts supported onthe nodes of the metal organic framework (MOF) NU-1000 for these conversions. The goals of this workare to identify the catalytic descriptors and electronic structure properties of such catalysts that promoteC-C and C-H bond chemistry and apply traditional methods in computational catalyst screening to predictcatalytic activity.

To this end, six first-row transition metal cations (Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+) were evaluatedcomputationally as single-site catalysts for the conversion of ethene to 1-butene, i.e., (2C2H4 → C4H8).These catalysts were modeled in two ways: 1) supported on the zirconium oxide/hydroxide nodes of themetal-organic-framework NU-1000, and 2) supported on a generic 1 metal hydroxide cluster. The forma-tion energies of co-adsorbed hydrogen and ethene (i.e., (H/C2H4)∗) and adsorbed ethyl (i.e., C2H5

∗) wereidentified as catalytic descriptors and were used in microkinetic modeling to identify the descriptor valuesthat maximize the production rate of 1-butene. Additionally, using degree of rate control and degree ofcatalyst control analyses, it was determined that the rate controlling steps were either ethene insertion (C-Cbond forming) or β -hydride elimination (C-H bond breaking), depending on the catalyst metal, and thatthe (H/C2H4)∗) descriptor had the strongest influence on activity. Additionally, it was determined that thed orbital splitting arrangement, which in part determines the spin state of the metal cation site, is linked tocatalytic activity.

44

Synthesis of Highly Activity Fuel-cell Catalysts for Direct Methanol Fuel Cells

Bahareh Alsadat Tavakoli Mehrabadi, John W. Weidner, John R. Regalbuto and John R. Monnier

University of South Carolina

Platinum catalysts are effectively able to catalyze the oxidation of methanol to carbon dioxide in acidic me-dia. However, the surface Pt sites become rapidly poisoned by strongly adsorbed carbon monoxide (CO)that is produced during the oxidation process, limiting the overall rate of methanol oxidation. Studies haveshown that bimetallic catalysts composed of platinum (Pt) and ruthenium (Ru) are more active for the oxi-dation of methanol compared to catalysts composed solely of Pt. The mechanism by which these bimetalliccatalysts alleviate CO poisoning involves the adsorption of H2O on Ru sites to form a Ru-OH species, whichoxidizes CO strongly adsorbed on Pt to form CO2 and H+. Thus, it is important for Ru and Pt to co-existin close, proximal contact on the surface for the Ru-assisted oxidation of CO to occur. It follows that abimetallic catalyst where the Ru is evenly distributed in a controlled amount on the Pt surface should exhibitenhanced performance.

In this study, the method of Strong Electrostatic Adsorption (SEA) have been used that can yield supportedmetal nanoparticles with high dispersion and narrow size distribution. Catalysts prepared by SEA then usedas seeds for addition of secondary metal using Electroless Deposition (ED). These methods were used todemonstrate the preparation of series of carbon supported bimetallic catalysts containing Pt which were thencharacterized and evaluated for methanol oxidation reactions. These sets of catalysts have the small particlesize with narrow size distributions and show higher activity towards methanol oxidation in comparison tothe commercial supported Pt.

45

Computational Insights into Photo(electro)chemical Nitrogen Fixation over Titania Catalysts

Andrew J. Medford, Benjamin C. Comer and Marta C. Hatzell

Georgia Institute of Technology

Photocatalytic nitrogen fixation is a form of artificial photosynthesis capable of enabling distributed pro-duction of fixed nitrogen at near-ambient conditions from the nitrogen, water, and photons that are readilyavailable from the environment. The process has been demonstrated over titania catalysts through both re-ductive and oxidative pathways, although the currently observed nitrogen fixation rates are too low to bepractical for fertilizer synthesis and there is little fundamental understanding of the reaction mechanism orchemical phenomena that enable the process. Interestingly, the process occurs under environmental condi-tions and has been speculated to play a significant role in the global nitrogen cycle owing to the prevalenceof TiO2 in naturally occurring sands and man-made pigments. Despite the wide-ranging potential impactsof this reaction, first demonstrated nearly 75 years ago, the process has received relatively little attention andhas not been studied with modern techniques. This talk will briefly review the historical context and currentprogress toward photocatalytic nitrogen fixation, followed by a theoretical perspective into the thermody-namic driving forces and likely reaction mechanisms, with an emphasis on the potential for developingphotoelectrochemical processes. The computational results will be complemented by recent experimentsdemonstrating the feasibility of the reaction.

46

Mixed Oxide Based Redox Catalysts for Methane Partial Oxidation via a Cyclic Redox Scheme

Fanxing Li

North Carolina State University

The current study investigates a cyclic redox process for methane partial oxidation in absence of gaseousoxygen. Perovskite-structured redox catalyst is used for methane (partial) oxidation. In this process, activelattice oxygen in the redox catalyst is first used to partially oxidize methane into syngas, the oxygen-leanredox catalyst is subsequently regenerated with H2O or CO2, producing H2 or CO. We report a family ofhighly effective redox catalyst for the abovementioned redox reactions. Extensive testing in differential andintegral bed reactors indicate that the redox catalyst is capable of achieving over 95% syngas selectivity inthe methane partial oxidation step. The reduced redox catalyst is shown to be capable of converting CO2 intoa near pure CO stream (or H2O into H2). The exceptional syngas selectivity and H2O/CO2 conversion areattributed to a combination of the satisfactory thermodynamic properties of the redox catalyst and enhancedredox kinetics through support and oxygen carrier interactions. The abovementioned redox catalysts areshown to be effective for the hybrid solar-redox process developed in our group.

47

Development and Implementation of High-throughput Gas Chromatography via EthyleneEpoxidation

Erdem Sasmaz 1, Garrett Buchman 2, Kate Mingle 1 and Jochen Lauterbach 1

1. Department of Chemical Engineering, University of South Carolina2. Department of Chemical and Biomeolecular Engineering, Clemson University

Gas chromatography (GC) is a versatile analysis technique that is heavily used for the quantitative andqualitative analysis of chemical mixtures. Samples analyzed using traditional GC provides sensitive andaccurate information, yet requires a long analysis time to complete one single measurement, which makesit difficult to be implemented in a high-throughput experimentation (HTE). One possible way to applyGC to the HTE is to inject samples with a fast pseudo-random binary sequence that generates overlappedchromatograms. These overlapped chromatograms can be deconvoluted into the individual sample chro-matogram using Hadamard Transformation.

In this work, a fast injection GC algorithm has been developed and implemented to test ethylene epoxidationreaction using a 16-channel high-throughput reactor. The reactors were loaded thirteen catalyst formulationsand exposed to mixtures of ethylene and oxygen at reaction temperatures of 250◦C, 275◦C and 300◦C. Theeffluent concentrations were analyzed using HT-GC, single GC injection and parallel Fourier transform In-frared (FTIR) spectroscopy simultaneously, and the results were compared with each other.

Our results confirm that the HT-GC could accurately be implemented to a multichannel reactor system anddecrease the analysis time required to complete the measurements. Using the HT-GC, the throughput of theGC could be increased by at least 4.5 times. The thirteen samples could be analyzed accurately in 1.1 husing a 9-bit injection sequence, while this analysis would take 5 h to complete using a single GC injection.Ethylene conversions could be predicted within 10% mean error in comparison to the single GC injections.These results confirm that the HT-GC system can be used for the fast analysis of multiple reactors and openspossibilities to perform kinetic measurements in single channels.

48

Design, Synthesis and Kinetics of Solid Catalysts for Sustainable Hydrocarbons Activation:Exploring Synergistic Effects in Heterogeneous Catalysis

Carlos A. Carrero

Auburn University

In the first part of my talk I will present the most relevant results I obtained during my PhD and Postdoctime on the oxidative dehydrogenation of light hydrocarbons. I’ll highlight on how such findings inspiredme to pursue an academic career. In the second part, I’ll comment on the infrastructure and facilities I havein my Lab in order to stimulate collaborations among the southeastern catalysis community.

49

Catalyst Development for Large Scale Conversion of Landfill Gas to Liquid Fuels

Xianhui Zhao 1, Paul Stachurski 1, Devin Walker 2, Tim Roberge 2, Matthew Kastelic 1, Shrinand Shah 1,Babu Joseph 1,2 and John N. Kuhn 1,2∗

1. Department of Chemical & Biomedical Engineering, University of South Florida, Tampa, FL 33620,United States

2. T2C-Energy, LLC, 3802 Spectrum Blvd Suite 128p, Tampa, FL 33612, United States

Although literature studies of methane reforming are mainly on powder catalysts, formed catalysts (e.g.pellet) are required for large scale use. The NiMg/Ce0.6Zr0.4O2 powders demonstrated promising catalyticperformance towards tri-reforming of surrogate biogas [1]. Therefore, the NiMg/Ce0.6Zr0.4O2 catalyst wasused as a basis to develop pellets in this study. The NiMg/Ce0.6Zr0.4O2/Al2O3 pellets were initially de-veloped using a wet impregnation method and employed for the tri-reforming to achieve high conversionsand desirable selectivity and stability, but led to a low space velocity due to the large volume of alumina.In order to increase the space velocity, the NiMg/Ce0.6Zr0.4O2 pellets have been developed via extrusion.Similar catalyst performance was achieved, but now at a space velocity capable of large scale application.To enable use of this catalyst, the mechanical strength needed enhanced. By optimizing the binder and waterconcentrations and the slurry pH, the radial crush strength increased by 120%. This pellet catalyst was thenused in a demonstration scale tri-reforming and Fischer-Tropsch Synthesis (TriFTS) system to convert realbiogas (landfill gas) to liquid hydrocarbon fuels. A Co/SiO2 eggshell catalyst was used for the FTS reactor[2]. With gas cleanup, the performance of the process matched that of using the surrogate biogas. Analysisindicated the liquid hydrocarbon fuel was similar to commercial diesel other than it contained less aromaticsand sulfur. Overall, 30% of the biogas‘s energy is recovered in the liquid hydrocarbon product, which com-pares favorably to electricity generation and also results in a value-added product. The NiMg/Ce0.6Zr0.4O2pellet catalysts are promising for commercial scale applications. Authors affiliated with T2C-Energy, LLCdisclose an interest in the technology.

References:1. Walker, Devin M., Sandra L. Pettit, John T. Wolan, and John N. Kuhn. Synthesis Gas Production toDesired Hydrogen to Carbon Monoxide Ratios by Tri-reforming of Methane using Ni-MgO-(Ce, Zr) O2Catalysts. Applied Catalysis A: General 445 (2012): 61-68.2. Gardezi, Syed Ali, John T. Wolan, and Babu Joseph. Effect of Catalyst Preparation Conditions onthe Performance of Eggshell Cobalt/SiO2 Catalysts for Fischer-Tropsch Synthesis. Applied Catalysis A:General 447 (2012): 151-163.

50

Enhanced CO2 Conversion to CO by Silica Supported Perovskite Oxides at Low Temperatures

Bryan J. Hare, Debtanu Maiti, Yolanda A. Daza, Venkat R. Bhethanabotla and John N. Kuhn

University of South Florida

Feasible reforming of CO2 to valuable hydrocarbons is crucial for energy security and a balanced carboncycle. Our process, reverse water gas shift chemical looping (RWGS-CL), manifested efficient CO2 toCO conversion at a low temperature of 600◦C with unprecedented rates using the La0.75Sr0.25FeO3 (LSF)perovskite-type oxide amalgamated with silica. The LSF-silica composite (25% LSF by mass) promoteda notable extent of oxygen vacancies, a key parameter for CO2 conversion, in the active phase. Through-out eight cycles of RWGS-CL, CO generation yields of LSF on silica surpassed those of LSF alone byabout 200%, producing 0.8 mmol CO gLSF−1min−1. This significant improvement was concomitant with adecreased average LSF crystalline size further retained at low reaction temperatures. Evidence of this phe-nomenon points to wettability by silica and controlled quantities of secondary phases formed during particleaggregation. We demonstrated silica as an appropriate stable platform for improving Earth-abundancy inperovskite-based redox materials for industrial low temperature CO2 thermochemical conversion.

51

Low Temperature CO2 Conversion to CO Using Earth Abundant Perovskite Oxides

Debtanu Maiti, Bryan J. Hare, Yolanda A. Daza, Adela E. Ramos, Venkat R. Bhethanabotla and John N.Kuhn

University of South Florida, Tampa, FL - 33620

Depletion of fossil fuel reserves along with the associated negative environmental impacts of their use haveled to a focus on alternative energy. Solar energy has garnered a lot of attention and coupling this abun-dant form of energy for efficient reutilization of waste CO2 presents a novel approach. However, even withsignificant research efforts over the last decade, CO2 conversion is still plagued by issues that limit its imple-mentation at large scale. Solar thermochemical (STC)1,2 was perceived as the solution to poor conversionrates. However STC operates at above 1000◦C, making to unfit for industrial purpose. Reverse water gasshift chemical looping (RWGS-CL) works on similar principle as STC, the only difference being hydrogenis used as a reducing agent. This allows for reducing the temperatures of operation to ∼600◦C. The successof this methods relies on the oxygen vacancy formation characteristics of the perovskite oxides (ABO3) usedas the platforms of CO2 conversion cycles. Perovskite oxides also present a vast opportunity for materialproperty tuning by simply varying the compositions of ‘A’ and ‘B’ sites. Thus, using DFT-calculated oxygenvacancy formation energy as the descriptor for this process, we predicted several earth abundant materials(ABO3, A10.5A20.5BO3, AB10.5B20.5O3, and A10.5A20.5B10.5B20.5O3) with CO2 conversion capabilities.These materials were synthesized via Pechini method and demonstrated unprecedented CO2 conversionrates. The lanthanum and calcium based materials revealed highest CO2 conversion rates at lowest temper-atures (450-500◦C) via RWGS-CL. These materials also showed long term stability presenting themselvesas possible candidates for industrial operation. Efficient conversion of CO2 to CO via this process enablesthermal integration with Fischer Tropsch (FTS) for sustainable generation of hydrocarbons. An empiricalmodel has also been proposed for oxygen vacancy formation energy allowing for future prediction of mate-rials.

References:1. W. C. Chueh, C. Falter, M. Abbott, D. Scipio, P. Furler, S. M. Haile and A. Steinfeld, Science, 2010, 330,1797-1801.2. A. H. McDaniel, E. C. Miller, D. Arifin, A. Ambrosini, E. N. Coker, R. O’Hayre, W. C. Chueh and J.Tong, Energy & Environmental Science, 2013, 6, 2024-2028.

52

Guided Mixed-Oxide Synthesis for Ethane Partial Oxidation

Juan Jimenez, Kate Mingle, Teeraya Bureerug, Cun Wen and Jochen Lauterbach

University of South Carolina

Efficient design of novel catalyst generally requires a clear understanding of the synthesis-performance re-lationship. More specifically, fundamental and empirical information is required to elucidate how differentsynthesis parameters affect both the final catalyst structure and its corresponding catalytic activity. Nano-structured catalysts are complex systems, in which multiple factors can influence catalytic activity. Suchfactors include particle size, surface structure, composition, or synthesis method; to name a few. Those fac-tors have been found to be important in many industry-relevant reactions, such as ethane partial oxidation(EPO). For EPO, a promising reaction to upgrade ethane found in shale gas, catalysts are typically preparedthrough trial and error approaches without a thorough understanding of the highly correlated relationshipsbetween the synthesis parameters, structure factors, and the catalytic activity. If a systematic understandingis made available, it will be greatly beneficial to the design of more active/selective catalysts for EPO.

In this study, we utilize a statistical Design of Experiments (DOE) methodology to elucidate the relationshipbetween different synthesis parameters and their effect on the catalytic activity and selectivity of EPO.Specifically, we will be exploring the effects of dopant addition to a base MoVNbO catalyst, which hasshown promising activity for EPO and other hydrocarbon partial oxidations. To capture the entire spectrumof possible effects from dopant addition to the host lattice we will provide a detailed characterization ofthe crystalline structure, particle size distribution, reducibility, acid strength, and the catalytic activity ofEPO. Furthermore, we will be able to link changes in synthesis parameters to not only changes in activityand selectivity in EPO, but also simultaneously correlate changes in activity to changes in redox properties,morphology, or the catalyst composition with statistically significant guidance from the DOE. With thisknowledge, we will be able to develop heuristics and guided synthesis parameters for the development ofnovel catalyst for ethane partial oxidation.

53

Aqueous-Phase Hydrogenation of Succinic Acid Using Bimetallic Ir-Re/C catalysts

Jayson Keels 1, Xiao Chen 2, Changhai Liang 2, John Monnier 1 and John Regalbuto 1

1. University of South Carolina, Department of Chemical Engineering, Columbia, SC 29208, USA2. Dalian University of Technology, Department of Chemical Engineering, Dalian, Liaoning 116024, China

Many important building block chemicals, including C4 compounds, are produced as co-products fromnaphtha cracking in the production of ethylene. However, because of the abundance of natural gas, ethyleneis increasingly being produced by gas cracking which provides almost no co-products. Thus, it is imperativeto explore alternative sources to meet the demand of these longer chain, platform chemicals. One alternativeis bio-succinic acid, a C4-diacid, which has been named by the Department of Energy (DOE) as one of thetop 12 candidates for most economically-viable building block chemicals from biomass.

To reach many of the end markets that succinic acid is used as feed, it is necessary to hydrogenate it todownstream high-performance chemicals such as γ-butyrolactone, 1,4-butanediol, and tetrahydrofuran. Sig-nificant progress has been made to tune selectivity and enhance activity of this reaction in aqueous media.Most notably, researchers have found bimetallic systems that utilize one traditional hydrogenation metalfrom the platinum group metals (PGM) and one oxophilic metal, such as Re, have remarkable synergisticeffects. Ir is one of the PGM’s that has not been explored in combination with Re for this reaction.

A series of monometallic and bimetallic Ir-Re catalysts supported on activated carbon have been preparedusing strong electrostatic adsorption (SEA) and tested for aqueous phase hydrogenation of succinic acid.While Ir displayed essentially no activity and Re displayed low activity, the optimal bimetallic catalystexhibited a nine-fold increase in activity. This has been primarily attributed to a bifunctional effect wherethe two different functions of each metal can work in unison to catalyze the critical hydrogenolysis andhydrogenation reaction steps. Characterization has shown that there is strong interaction between the twometals in the active bimetallic catalysts.

54

Solvation Effects on MWW-2D Zeolite Framework for Dissociation of β -O-4 Linkage

Varsha Jain and Neeraj Rai

Mississippi State University

Lignin, which comes from plant cell walls is a potential renewable source of biofuels, chemicals, and othervalue-added products. It consists of different aryl ethers, irregularly connected by a variety of linkages (β -O-4, 5-5, β -5, 4-O-5, β -1, dibenzodioxocin, and β -β ), which creates a complex structural network; hence,selective bond breaking events are required for the production of other useful products. Out of all theselinkages β -O-4 linkage is predominant. Protonated zeolites are the subject of growing interest due to theirmoderate acid strength. In this work, properties and behavior of protonated Al based MWW-2D zeolitesin the presence of different solvents (water and methanol) have been investigated by means of periodicdensity functional theory (DFT) approaches. These substituted Al sites can create catalytic environmentto cleave C-O bond. Different solvents can also affect structure and acidity of catalyst for the cleavage ofC-O bond presents in the lignin dimers. Effect of changing the ratio of surface substituted H and OH hasbeen investigated also. Overall, model acid substituted zeolites in MWW framework are characterized byfirst principles DFT calculations, with the aim of gaining detailed insights into the reaction mechanism fordissociation of β -O-4 linkage.

55

ALD Modified Au-Based Catalysts for Propylene Epoxidation

Zheng Lu 1, Zili Wu 2, C. Heath Turner 3 and Yu Lei 1

1. Department of Chemical and Materials Engineering, University of Alabama in Huntsville, Huntsville,AL

2. Chemical Sciences Division and Center for Nanophase Materials Sciences, Oak Ridge NationalLaboratory, Oak Ridge, TN

3. Chemical and Biological Engineering, University of Alabama, Tuscaloosa, AL

Propylene oxide (PO) is a chemical intermediate of great value and in high demand. It is used to produceuseful polymeric materials. A direct catalytic epoxidation of propylene with hydrogen and oxygen to POrepresents an environmentally friendly process and can be fulfilled over gold-titanium based catalysts. Iso-lation of the titanium was found to significantly reduce the cracking of propylene to ethanal and carbondioxide[1-2]. However, these sites could gradually deactivate due to the change of titanium oxidation stateand coordination, leading to low selectivity and coke formation. In addition, gold nanoparticles appear tosinter at high temperature, resulting in low activity and deactivation.

In this work, the loading and location of TiO2 are precisely controlled by means of atomic layer deposition(ALD). The growth rate of TiO2 ALD was studied using in situ quartz crystal microbalance (QCM) andex situ spectroscopic ellipsometry. Two series of gold-titanium based catalysts, Au/TiO2/SiO2 and inverseTiO2/Au/SiO2, were synthesized and studied in detail using a number of characterization techniques suchas in situ X-ray absorption spectroscopy and transmission electron microscopy. The location and loadingof the TiO2 was found to alter the reactivity, selectivity and capability of catalyst regeneration. The inverseTiO2/Au/SiO2 catalysts enabled high PO selectivity ( 90%) and easy regeneration. Moreover, kinetic studieswere carried out to reveal the possible reaction mechanisms.

References:1. S. T. Oyama, Mechanisms in Homogeneous and Heterogeneous Epoxidation Catalysis. Elsevier, 2011.2. E. E. Stangland, B. Taylor, R. P. Andres, and W. N. Delgass, "Direct Vapor Phase Propylene Epoxi-dation over Deposition-Precipitation Gold-Titania Catalysts in the Presence of H2/O2: Effects of Support,Neutralizing Agent, and Pretreatment", J. Phys. Chem. B, vol. 109, no. 6, pp. 2321-2330, Feb. 2005.

56

Benchmarks for CO and CO2 Adsorption on MnO(100): a Comparison of DFT to ExperimentalData

Han Chen, Xu Feng and David F. Cox

Virginia Tech

Density functional theory (DFT) is commonly used to investigate adsorption and reaction processes onsurfaces. While it is widely used, the applicability of DFT to highly correlated transition metal oxide systemswith unpaired d-electrons is problematic, especially when using plane wave basis sets. A primary issue isthe lack of quality experimental data for adsorbate and reaction systems on well-defined (single crystal)transition metal oxide surfaces to provide benchmarks for the applicability of current DFT methods andthe future development of new methods. With this goal in mind, we have established benchmarks for theadsorption energy of CO and CO2 on MnO(100) terraces using temperature programmed desorption (TPD).In this talk we present the obtained adsorption energies of aforementioned gas molecules on MnO(100),determined using TPD experiments and compare them to DFT simulations. We find in the case of COthat the weak adsorption energy measured with TPD agrees well with DFT+U simulations that includecorrections for van der Waals interactions, but there is substantial deviation between the two in the case ofCO2. DFT simulations predicts that CO adsorbs at surface Mn sites in an atop configuration, while CO2adsorbs as a bent CO2 anion at surface oxygen anion sites.

57

Selective Oxidation of n-Butane to 1-Butanol over Transition Metal Catalysts Encapsulated byMetal-Organic Frameworks

Jiazhou Zhu and Rachel Getman

Clemson University

Density functional theory (DFT) is used to model reaction pathways of the oxidation of n-butane to 1-butanolover several different metal alloy and pure metal catalysts under steric constraints, and the implications ondesigning MOF-encapsulated catalysts are discussed. MOFs are porous crystalline solids comprised ofmetal-based nodes connected by organic "linker" molecules. Recently, they have been successfully grownaround metal nanoparticles, creating porous networks at the MOF/catalyst interface, which have been shownto promote the regioselective hydrogenation of trans-1,3-hexadiene to 3-hexene. In this work, we explorethe use of sterically constrained catalysts for selective alkane oxidation. We are specifically interested inn-butane oxidation to 1-butanol, which is important in the pharmaceuticals, energy, and specialty chemicalsindustries. It is a useful reaction for studying regioselectivity since 2-butanol is thermodynamically morestable than 1-butanol. In this work, we investigate n-butane oxidation to 1-butanol and 1-butanal on the (111)facets of Ag3Pd, Cu3Pd, PdZn, Cu, and Pd. We use a "surrogate pore" comprised of helium atoms to modelthe MOF pores. We compute the energies of reaction intermediates and transition states involved in 85 totalreactions using DFT, and we develop scaling relationships linking these energies to simpler "descriptors"of catalytic activity. We use these scaling relationships in microkinetic modeling to identify the optimaldescriptor values, which maximize the rate and selectivity to 1-butanol. Further, we perform degree ofrate control analysis in order to reveal the catalytic intermediates and transition states that have the greatestcontrol on the rate. The results reveal design criteria for n-butane selective oxidation to 1-butanol.

58

Using Scaling Relationships to Efficiently Calculate Thermodynamic and Kinetic QuantitiesInvolved in the Aqueous Phase Reforming (APR) of Glycerol

Tianjun Xie

Clemson University

Aqueous phase reforming (APR) of biomass sustainably supplies hydrogen gas, making it an important com-ponent of future biorefineries; however, problems with the cost as well as activity and selectivity of presentprecious metal based catalysts impede its broader adoption. Ideally, new catalysts would be designed tooptimize activity and selectivity; however, too little is known about reaction mechanisms to design catalystsfor APR. This is complicated by the fact that the primary biomass substrates are large molecules, mean-ing that their reaction networks are large, and because of the presence of liquid water. Since liquid watermolecules are in constant thermal motion, the structure of liquid water at the catalyst interface is configu-rationally disordered. Differences in the ways that the various liquid configurations interact with catalyticsurface intermediates can influence catalytic thermodynamics and kinetics significantly. Understanding themechanism of APR requires understanding these various effects; however, present computational strategiesbased solely on density functional theory (DFT) are computationally prohibitive for such large and com-plicated reaction networks. In this work, we investigate the mechanism of APR reactions in the context ofglycerol reforming. To calculate the reaction network, we demonstrate a strategy that combines classicalmolecular dynamics (cMD) simulations and linear scaling relations (LSRs) to capture different liquid con-figurations and their influences on catalytic thermodynamics and kinetics. Specifically, we show how LSRscan be combined with cMD to estimate aqueous phase binding energies and reaction energies and howBrφnsted-Evans-Polanyi (BEP) relations can be used to estimate aqueous phase reaction barriers. Thesemethods achieve high accuracy when compared to the analogous DFT calculations and can be carried outin a fraction of the time. Further, they should be useful for other aqueous phase heterogeneously catalyzedreactions, as well.

59

Control of the Activation towards Unsaturated C-C Bonds over Ni-based Intermetallic Compounds

Yuanjun Song, Yang He and Siris Laursen

University of Tennessee at Knoxville

Intermetallic compounds (IMCs) comprised of atomically ordered mixtures of non-noble transition metalsand post-transition metal or semimetal elements exhibit unique and tunable surface chemistry towards C-H,C-C, and C-O bonds of various saturations that is of significant interest to the greater heterogeneous catalysiscommunity. Understanding and controlling these unique properties in reactions that require a specific degreeof activation may lead to dramatic improvements in catalytic activity and selectivity for the production andutilizing of unsaturated hydrocarbons. Despite the apparent tunability and demonstrated catalytic activity ofIMCs in several scientifically and industrially relevant reactions, how the surface and catalytic chemical ofIMCs is produced and tuned through the choice of constituent elements and bulk and surface compositionis still unclear. In this study, a combined computational and experimental approach has focused upon thesurface and catalytic chemistry of nickel and boron group-based IMCs. General trends in surface reactivitytowards unsaturated C=C bonds were found as a function of p-block element selection with compositionsisolated that would either preserve or activate and drive reaction or dissociation of the bond. Surface chem-istry towards oxygen and hydrogen was also investigated to lend insight into the activation of C-H, O-H,and C=O bonds for application in reforming and selective hydrogenation reaction conditions. The effect ofbulk and surface composition of Ni+Ga IMC was studied further in depth due to their ability to performlow temperature activation of saturated hydrocarbons and water in reforming reactions. Experimentally,phase-pure, oxide-supported nanoparticle Ni+Ga were synthesized and investigated in propane reforming.High performance catalysts were isolated rapidly using computational direction and further studied to un-derstand the effect of IMC particle size, bulk and surface composition, and synthesis conditions on activityand selectivity.

60

Molecular Simulation Study of How the Structure of Liquid Water Affects the Free Energies ofReaction in Aqueous Phase Heterogeneous Catalysis

Xiaohong Zhang and Rachel B. Getman

Clemson University

Many heterogeneous catalysis reactions occur in aqueous phase, such as aqueous phase reforming (APR),Fischer-Tropsch synthesis, electrocatalytic water splitting, etc. It is important and challenging to understandhow water influences the chemistry, mechanism, thermodynamics, and kinetics of reactions on metal cat-alyst surfaces. Recent work by our group and others has shown that H2O molecules can form hydrogenbonds (HB) with reaction intermediates, alter their adsorption energies, co-catalyze certain reactions, affectkinetic barriers and reaction mechanisms, amongst other phenomena. We are interested not only in the rolesthat liquid H2O molecules play, but also how these phenomena influence the rates and equilibria of catalyticsurface reactions. For example, we previously found that hydrophilic adsorbates form stronger and morestable HB with H2O molecules than hydrophobic adsorbates, which we postulated would lead to greaterdegrees of order in the interfacial water structure around hydrophilic adsorbates than for hydrophobic ones.We further postulated that this would give rise to a free energy effect in reactions where hydrophilic adsor-bates are converted into less hydrophilic adsorbates or even hydrophobic ones, e.g., in APR reactions wheresugar alcohol molecules are sequentially deprotonated down to CO2 and H2 (and other analogous reactions).In this work, we use density functional theory (DFT) and methods in molecular dynamics (MD) to studythese effects in the context of the decompositions of CH3OH and NH3 over Pt catalysts. Specifically, wecompute the free energies of different surface intermediates along the pathways for these reactions underliquid H2O using the following methods: (1) Potential of mean force (PMF), calculated from the radial dis-tribution function (RDF), which gives the free energy due to configurational fluctuations in the liquid H2Ostructure, and (2) Free energy perturbation (FEP) and (3) Thermodynamic integration (TI), which give thefree energies of solvation for the different adsorbates. We provide values for these different contributionsand discuss how they influence the reaction energies on the surface under liquid H2O.

61

Determining How Support pH and Hydrophilicity Influence Activity and Product Distributions inAqueous Phase Reforming of Glycerol

Torrie E. Sewell, David A. Bruce and Rachel B. Getman

Clemson University

The catalytic conversion of biomass derivatives, such as glycerol, to platform chemicals or energy productscould lessen dependence on fossil fuels, thus providing a sustainable source of energy for the world’s de-mand. One method for performing these conversions is aqueous phase reforming (APR), which is of interestbecause it utilizes low operating temperatures. Presently, catalysts synthesized to carry out APR are com-prised of noble metals supported on metal oxides. One of our goals is to learn how these materials functionso that we can design less expensive catalysts for APR and other similar reactions. One of the challenges inunderstanding how APR catalysts function is the aqueous environment itself: H2O molecules not only in-fluence catalytic chemistry and physics, they also impede our ability to observe these influences. Our groupand others have recently reported several ways in which H2O influences the catalytic chemistry of glycerolAPR and related reactions over transition metal catalysts. However, how the support participates, and howthe catalytic chemistry is influenced by the H2O/catalyst/support interface is still largely unknown. In thisresearch, we identify how multiple support properties influence catalytic activity and product distributions inglycerol APR. Specifically, we examine the effects of acidity (which is dependent on the active Bronsted andLewis acid sites) and hydrophilicity on Pt-catalyzed glycerol APR. Acidity of the support is caused by thepresence of Bronsted and Lewis acid/base sites on the support surface, which promote some of the reactionsteps in APR. Additionally, they influence the pH of the catalyst due to the positive and negatives sites on thesurface, and alter the hydrophilicity of the catalyst, due to the presence of H+ and OH− ions, and these ef-fects influence the structure of liquid H2O at the interface, which in turn influences the thermodynamics andkinetics of catalytic reactions. Our goal is to identify the support properties that lead to optimal performancebut also have the least influence on performance, as these materials can be best compared with simulationwork from our group. Synthesized catalysts undergo various characterization methods, including scanningelectron microscopy, energy dispersive X-ray spectroscopy, and thermogravimetric analysis. Results fromthese characterization methods as well as product distributions from catalytic experiments will be presented.

62

Effect of Synthesis Methods on the Performance of NiO/CexZr1-xO2 Catalysts Converting Methaneto Higher Alcohols

Yimeng Lyu, Chukwuemeka Okolie, Ben Deglee and Carsten Sievers

Georgia Institute of Technology

Methane is abundantly available as the principle component of natural gas and as part of oil reserves. How-ever, transportation of methane from remote locations is very difficult. Therefore, natural gas by-productsfrom oil wells are often vented or flared. Over the years, many efforts have been made to develop efficientprocesses for converting methane into liquid products.

Our group has developed nickel oxide on ceria-zirconia support (NiO/CZ) catalysts that is capable of con-verting methane to higher alcohols at 15% methane conversion and 6.6% alcohol yield on a C atom basis(3.7% ethanol yield, 2.9% methanol yield). Our previous study showed that NiO clusters act as Lewis acidsites in the catalytic system and are capable of activating methane. The small NiO cluster size on the cata-lyst is essential for formation of alcohols rather than the carbonaceous deposits that form on large particles.Additionally, we also found that the redox-active CZ support is responsible for the activation of O2.

Different synthesis methods have a marked effect on the reactivity of these catalysts. To further investigatethe effect of synthesis methods, four types of catalysts were prepared, using dry impregnation, strong elec-tronic adsorption, flame combustion and co-precipitation as synthesis methods. The concentration of Lewisacid sites on each catalyst was characterized by pyridine adsorption followed FTIR study. So far, the catalystmade by strong electronic adsorption showed the best methane conversion at 18%, and NiO/CZ with 6 wt%Ni made by co-precipitation showed best selectivity to alcohols with 47%. In bulk synthesis techniques (i.e.,co-precipitation and combustion synthesis), a part of the NiO was incorporated in to the bulk of the catalyst.Thus, the amount of NiO was varied to optimize the concentration of exposed NiO species and achieve theoptimal performance.

63

Orbitalwise Coordination Numbers as New Descriptors for Oxygen Reduction Catalyst Design

Siwen Wang and Hongliang Xin

Virginia Tech University

Low temperature polymer electrolyte membrane (PEM) fuel cells have great potential as a clean and effi-cient electric energy generation system. An important obstacle to the commercialization of this technologyis the significant voltage loss in converting chemical energy of fuels (e.g., H2) to electric energy, mainlydue to the sluggish electrochemical kinetics of the oxygen reduction reaction (ORR) at the cathode. Thestate-of-the-art metal electrocatalyst, containing small nanoparticles of Platinum (Pt), sacrifices 300 mVfor appreciable current densities [1]. Therefore, there has been a lot of interest in identifying materials withfine-tuned strains and ligands for better performance than pure Pt electrocatalysts.

Since the strain and ligand effects are not mutually independent of each other, i.e., changes in the localenvironment of the Pt surface sites via alloying affects both the ligand and strain effects, it is not obviouswhich metals should be introduced in what geometric arrangements to develop superior materials. For thatmatter, a physically intuitive descriptor that can be used to narrow down materials selection is important.Recently, we have developed the orbitalwise coordination numbers for describing the reactivity trends ofcoinage metals [2]. In this talk, we are extending the concept to late transition metals, e.g., Pt. We show thatthere exists the linear scaling correlations of orbitalwise CNs with the *O, *OH, and *OOH free formationenergy on Pt sites. With this new descriptor, we have identified several multi-metallic nanostructures (areactive Pt monolayer deposited on a core of a nanoparticle that usually contains Pt-alloys) with enhancedactivity toward ORR.

References:1. J. K. Nφ rskov, J. Rossmeisl, A. Logadottir, L. Lindqvist, J. R. Kitchin, T. Bligaard, and H. Jónsson, J.Phys. Chem. B 108, 17886 (2004).2. X. Ma and H. Xin, Phys. Rev. Lett. 118, 036101 (2017).

64

Additive Manufacturing of Solid Oxide Fuel Cell Stacks

Shenglong Mu, Yuzhe Hong, Jincheng Lei, Zeyu Zhao, Dong Jiang, Phaneuf Vincent, Fei Peng, Hai Xiaoand Jianhua Tong

Clemson University

Solid oxide fuel cells (SOFCs) have been proved to be one of the most efficient devices for converting fu-els into electricity in an environmental benign way. The fabrication technologies to obtain SOFC stackswith high efficiency, large power density, and high reliability has been intensively pursued, especially forthe recently emerged low temperature (LT) proton conducting SOFCs. Furthermore, the delamination andcracks in SOFC stacks are the main issues that destroy the performance of the SOFCs fabricated in con-vectional ways (e.g. tape casting followed by lamination). The addictive manufacturing technology (e.g.3D printing) is a promising technology to effectively solve the delamination and crack issues of the stackedSOFC by using the viscous paste as the building materials, which can improve the bonding between thelayer components. In addition, the layer-by-layer manufacturing technologies allow for the fabrication ofhighly compacted SOFC stacks. Comparing with conventional technologies, the addictive manufacturingtechnology is potentially to obtain crack-free, delamination-free, and highly compacted SOFC stacks withhigh flexibility in geometry design. On the other hand, the solid-state reactive sintering (SSRS) technologydeveloped recently in our group allows for the formation of the desired phases and densities of SOFC com-ponents from cost-effective simple oxide and carbonate precursors. This SSRS technology can well controlthe thermal expansion coefficients of different SOFC component layers. In fact, the sandwiched SOFC but-ton cells have been fabricated by this SSRS method in our previous work.

Our interest is to combine the additive manufacturing (e.g. 3D printing) technology and solid state reactivesintering technology to fabricate proton conducting SOFC stacks. The preliminary work will discover theprintable SOFC component pastes for 3D extrusion and demonstrate the feasibility of one-step firing of theSOFC stack multilayers by SSRS technology.

Geometry is one of the key for high efficiency solid oxide fuel cell. Cost-effective synthesis method combingwith addictive manufacturing technology is one potential and valuable way for boosting the efficiency ofSOFC.

65

The Effects of Long Term Sulfur Exposure on Three Way Catalyst Performance in Passive SelectiveCatalytic Reduction Systems

Calvin R. Thomas 1, Josh A. Pihl 2, Jochen A. Lauterbach 1 and Todd J. Toops 2

1. University of South Carolina, Columbia, SC 29033 (United States)2. Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

Lean burn gasoline engines can provide increased fuel efficiency over conventional, stoichiometric enginesthrough an increased air-fuel ratio (AFR). However, NOx in the lean exhaust cannot be reduced by three-way catalysts (TWC). Passive selective catalytic reduction (SCR) is a promising approach for the controlof NOx emissions in lean burn systems. By periodically operating rich, NH3 can be produced over a TWCand stored on a downstream SCR catalyst to reduce NOx emissions while the car is operating under leanconditions. Previous work has shown the viability of the system, but has not examined the long-term effectsof hydrothermal aging and sulfur exposure. This work is focused on evaluating these effects to determinethe long-term viability of a passive SCR system.

Two commercially formulated catalysts were studied: A Pd-only TWC, and a NOx storage TWC (NS-TWC),containing Ce for oxygen storage and Ba for NOx storage. These catalysts have been hydrothermally agedfor 100 hours at 900◦C. After aging, the catalysts were evaluated under lean-rich cycling using simulatedexhaust conditions. These evaluations were conducted before sulfation, after sulfation, and after desulfa-tion. Experiments probing individual reactions before and after sulfation were conducted to deconvolute theeffects seen in the full simulated exhaust experiments. Finally, the effect of rich phase AFR was investigatedas a potential route for mitigation of sulfation effects. During each of these experiments, the outlet concen-trations of the nitrogen species NOx, NH3, and N2O are monitored, while the reductants H2, CO, and C3H8are also measured.

Sulfation caused an increase in outlet C3H8, CO, and N2O, while the outlet H2 and the production of NH3were both decreased. In each case, the initial catalyst performance was recovered through desulfation. Thereaction probe experiments showed that when hydrogen is used as a reductant, production of NH3 is notsignificantly affected. However, when CO or C3H8 is used, the production of NH3 was decreased. Thisindicates that the deactivation of NH3 production is likely due to these reactions. It was also seen thatdecreasing the rich phase AFR was shown to be effective in increasing the production of ammonia in thepresence of SO2, leading to a shorter rich phase at the cost of increased fuel consumption while runningrich.

66

Stabilization of Catalytic Surfaces Using Bimetallic Core-Shell Structures

Andrew P. Wong 1, John Tengco 1, Arthur Reber 2, Sonia Eskandari 1, Shiv Khanna 2, John R. Monnier 1

and John R. Regalbuto 1

1. University of South Carolina, Columbia, SC 292012. Virginia Commonwealth University, Richmond, VA

Catalyst stability is often as important as catalyst selectivity. The loss of active sites and catalyst deacti-vation often make a catalytic system inadequate for chemical reactions. Therefore, techniques to enhancethe stability of catalytic surfaces are important in catalyst development. A possible way to stabilize thesenanoparticles is through differences in surface free energies (SFE) of core and shell metals. By placing alower SFE shell on top of a higher SFE core, a system is favored where the core metal anchors the shellmetal to lower the overall surface free energy of the bimetallic system.

Strong Electrostatic Adsorption (SEA) was used to make metal core nanoparticles. Electroless deposition(ED) was then used to synthesize the shell metals onto the metal cores. A bimetallic Ag-Ir system waschosen because of the large differences in SFE (Ir:∼3200 vs Ag:∼1300 ergs/cm2) as well as their differentchemisorption properties; Ag is inactive for H2 chemisorption. The work in this presentation focuses on sin-tering of core-shell catalysts due to thermal treatments in inert gases up to 800◦C. Loss of active Ir surfacesites was determined by selective chemisorption measurements. Sintering of Ag and Ir was determined byXRD and STEM.

The Ir metallic cores synthesized by SEA on γ-alumina were highly dispersed (< 2 nm diameter) asdetermined by both XRD and chemisorption. After thermal treatments to 800◦C, monometallic Ir andmonometallic Ag catalysts sintered to an average XRD particle size of 19 nm and 33 nm, respectively. Theaddition of a Ag shell to the Ir cores caused a suppression in amount of sintering (< 5 nm) observed for bothAg and Ir components compared to the monometallic analogs. Moreover, H2 chemisorption results for thebimetallic catalysts treated at 800◦C indicated a higher Ir dispersion, thus confirming the enhanced stabilityof the catalytic surface. This enhanced stability of the Ag-Ir surface and cause(s) for it were investigatedusing computational studies.

67

Catalytic Activities of Ag-Ir/Al2O3 Bimetallic Catalysts Prepared by Electroless Deposition

Sonia Eskandari, Andrew Wong, John Meynard Tengco, Abolfazl Shakouri, John R. Regalbuto and John R.Monnier

Department of Chemical Engineering, University of South Carolina

Alumina-supported, Ir@Ag bimetallic catalysts with a wide range of Ag coverages on monometallic Ir/γ-Al2O3 were synthesized in a controlled manner using electroless deposition. Both catalytic (Ag on Ir) andautocatalytic (Ag on Ag) deposition were observed; thus, a wide range of Ag weight % loadings were used togive fractional Ag coverages as high as 0.82. Analysis by chemisorption showed unusually high uptakes ofhydrogen on Ag-Ir surfaces following thermal treatment in flowing inert gases at 400 and 600◦C; computa-tional results suggest that isolated or small ensembles of Ir are capable of multiple hydrogen chemisorption.

Two different hydrogenation reactions were used to evaluate catalytic properties of the Ir@Ag catalysts,the hydrogenation of propylene (C3H6) and hydrogenolysis of methyl cyclopentane (MCP). Hydrogenationof C3H6 showed very high initial rates indicative of the large reservoir of hydrogen from Ag-Ir. How-ever, after consumption of hydrogen from these sites, specific activities returned to that of monometallic Irwith TOF = 15 sec−1 indicating that only Ir sites were operative at steady state conditions. Hydrogenoly-sis/hydrogenation of MCP was also used to determine the effects of Ag on selectivity to different reactionproducts, specifically, the hydrogenolysis of MCP to C1-C4 paraffins and isomerization to 2-methyl pen-tane (2-MP), 3-methyl pentane (3-MP) and n-hexane (n-C6). At Ag coverages than 0.53, selectivities tothe isomerization products decrease while cracking to C1-C4 hydrocarbons increases. Finally, in situ trans-mission Fourier transform infrared spectroscopy (FTIR) of CO adsorption indicates that the Ag is randomlydeposited on all types of Ir surface sites during the ED process.

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Development of Continuous Electroless Deposition for the Synthesis of Bimetallic Catalysts

Gregory L. Tate 1, Methasit Juthathan 2 and John R. Monnier 1

1. Department of Chemical Engineering, University of South Carolina2. Department of Chemistry, Mahidol University

Bimetallic catalysts are of great interest to the scientific and industrial communities, and several methodshave been developed and employed for their synthesis. Among these methods, electroless deposition (ED)has been shown to be an effective method for producing well-defined, supported bimetallic and core-shellsurface structures. Currently, ED is performed in a batch manner, but is restricted by the limited concentra-tions of ED components in the bath. Batch processing limits the quantity of catalyst produced per cycle, andmay also be complicated by variabilities related to batch production, reducing overall commercial appeal.Most importantly, this method is limited by the stability of the ED bath solution. This is especially importantfor preparation of Au-containing, bimetallic catalysts, which are often used in selective oxidation processes.To address these issues, a continuous approach to ED has been developed. Advantages to continuous pro-cessing include greater quantities of production per bath volume and more control over the final product,since the rate of ED can be more easily regulated. Further, continuous ED greatly mitigates the loadinglimitations of batch ED by operating within the stability limits of the ED bath, since the full concentrationsof reducing agent and reducible metal salt are not front-loaded in the bath.

In this presentation, the development of a continuous method for silica-supported Pt@Au catalysts usingthe AuCl4− complex as a starting material and reducing agents such as N2H4 and HCHO will be presented.Gold salts are typically very unstable in the presence of reducing agents and form Au0 nanoparticles; thus,concentrations of both AuCl4− and reducing agent must be carefully controlled to prevent thermal reduction.This characteristic is especially relevant for continuous ED since concentrations can be carefully controlled.The progress of ED is monitored in real-time using a UV-Visible spectrophotometric flow-through cellincorporated into a recirculation loop of the ED bath. In addition to measuring deposition of AuCl4−, theformation of unwanted Au0 nanoparticles is determined by the appearance of the Au0 lattice plasmon at 500- 600 nm. The use of stabilizing ligands for AuCl4− will also be discussed. This transformation of batch EDinto a continuous process should increase the industrial appeal of this method for Au-containing bimetalliccatalysts.

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Vacancy Creation Energy in Mn-containing perovskites: an Indicator for Chemical Looping withOxygen Uncoupling

Amit Mishra, Fanxing Li and Erik Santiso

North Carolina State University

Given energy demands and concerns over global climate change, there is a need for energy production withfacile CO2 capture. Chemical looping combustion (CLC) offers a solution to this problem, through a re-dox material capable of fossil fuel conversion with its lattice oxygen. In this two-step process, a metaloxide based redox material is reduced with a fuel and subsequently re-oxidized with air. This processoffers two main advantages 1) a pure oxygen source through a metal oxide, offering facile CO2 captureand 2) exergy recuperation as result of chemical looping reactions. However, this kinetic limitations ofsolid-solid interactions exist for solid fuel conversion. A potential solution to this problem is through a ma-terial that possesses chemical looping with oxygen uncoupling (CLOU) properties, i.e. spontaneous releaseof gaseous oxygen for solid fuel combustion. In this work, the AxA′1−xMnyB1−yO2 class of materials hasbeen identified for screening through first principles calculations of oxygen vacancy formation. In particular,vacancy formation in the dilute limit was determined for CaMnO3−δ , BaMnO3−δ , Ca0.75Sr0.25MnO3−δ ,CaMn0.75Fe0.25O3−δ . The presented work will show this is an efficient design parameter for CLOU prop-erties. The vacancy formation energy in the dilute limit was determined for all materials, showing two mainfindings: 1) Ca is favorable over Ba in the A site of the perovskite in terms of oxygen vacancy formationand 2) doping of Sr in the A site and Fe in the B site of CaMnO3, lowers the energy of vacancy forma-tion even further. These results correspond well to experimental findings, with both dopants increasingthe vacancy concentration below 700◦C. The results of this study show that vacancy formation energy canbe used a screening parameter in determining materials suitable for CLOU. Specifically, the results of thisstudy show the energy of vacancy formation in four materials: CaMnO3, BaMnO3, Ca0.75Sr0.25MnO3, andCaMn0.75Fe0.25O3 correspond to low temperature CLOU properties. In addition, the effect of Hubbard Uparameter did not effect the trend of vacancy formation energies versus material.

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Attendees List (As of 9-24-17)

QuantachromeEka Melani bruna.gomes@quantachrome.com

Eastman Chemical CompanyWilliam (Bill) Ketchie wketchie@eastman.com

H.E.L. Inc.Nelson Garcia garcia@hel-inc.com

Equilibar, LLCAlan Black alanblack@equilibar.comJeff Jenning jeffjennings@equilibar.com

Setaram InstrumentationChristine Martens christine.martens@setaram.comYves Cherisien yves.cherisien@setaram.com

Auburn UniversityCarlos Carrero cac0134@auburn.edu

Clemson UniversityAndrew Samstag asamsta@g.clemson.eduSteven Pellizzeri spelliz@clemson.eduRachel Getman rgetman@g.clemson.eduDong Jiang dongj@clemson.eduJiazhou Zhu jiazhoz@clemson.eduShenglong Mu smu@g.clemson.eduTianjun Xie tianjux@g.clemson.eduTorrie Sewell tsewell@g.clemson.eduXiaohong Zhang xiaohoz@g.clemson.eduZeyu Zhao zzhao2@clemson.eduJianhua "Joshua" Tong jianhut@clemson.edu

Georgia Institute of TechnologyAJ Medford andrew.medford@chbe.gatech.eduYimeng Lyu ylyu34@gatech.eduQandeel Almas qandeel.almas@gatech.eduCarsten Sievers carsten.sievers@chbe.gatech.eduAndrew Tricker atricker3@gatech.edu

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Mississippi State UniversityNeeraj Rai neerajrai@che.msstate.eduVarsha Jain vj181@msstate.eduAlicia Brown adb827@msstate.edu

North Carolina State UniversityLuke Neal lmneal2@ncsu.eduYunfei Gao ygao9@ncsu.eduFanxing Li fli5@ncsu.eduAmit Mishra amishra4@ncsu.eduRyan Dudek rbdudek@ncsu.eduSeif Yusuf smyusuf@ncsu.edu

Oak Ridge National LabMichelle Kidder kidderm@ornl.govYafen Zhang zhangy2@ornl.govTodd Toops toopstj@ornl.govAndrew Binder binderaj@ornl.govFelipe Polo-Garzon pologarzonf@ornl.govAditya "Ashi" Savara savaraa@ornl.govSreshtha Sinha Majumdar sinhamajumds@ornl.gov

University of AlabamaJingjing Ji jji4@crimson.ua.edu

University of Alabama in HuntsvilleZhuoran Gan zg0010@uah.eduZheng Lu zl0008@uah.edu

University of FloridaDavid Hibbitts hibbitts@che.ufl.edu

University of South FloridaJohn Kuhn jnkuhn@usf.eduXianhui Zhao xianhuizhao@usf.eduBryan Hare bryanhare@mail.usf.eduDebtanu Maiti dmaiti@mail.usf.edu

University of South CarolinaSonia Eskandari eskandas@email.sc.eduJochen Lauterbach lauteraj@cec.sc.eduCun Wen wencun6@gmail.comMozhdeh Parizad mparizad@email.sc.eduSean Noble srnoble@email.sc.edu

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Erdem Sasmaz sasmaz@cec.sc.eduBahareh Alsadat Tavakoli Mehrabadi tavakolb@email.sc.eduAndrew Wong awong@email.sc.eduCalvin Thomas CalvinRobertThomas@gmail.comGregory Tate gltate@email.sc.eduJuan Jimenez jiminezj@email.sc.eduJayson Keels keelsjm@email.sc.eduJohn Meynard Tengco tengco@mailbox.sc.eduElizabeth Barrow barrowe@email.sc.eduJeremiah Lipp jlipp@email.sc.eduKatie McCullough mccullke@email.sc.eduKate Mingle mingle@email.sc.eduSunkyu Kim sunkyu@email.sc.eduWenqiang Yang wenqiang@email.sc.edu

University of Tennesse, KnoxvilleMorghan Parker mparke40@vols.utk.eduYuanjun Song ysong26@vols.utk.eduSiris Laursen slaursen@utk.edu

University of VirginiaMonique Wilburn monique.wilburn1@yahoo.comYasser Jangjou yj3hd@virginia.edu

Virginia TechChun-Te Kuo chunte20@vt.eduEric Husmann ehus@vt.eduLiang Yu liangyu3@vt.eduZheng Li zhengl@vt.eduHongliang Xin hxin@vt.eduDavid Cox dfcox@vt.eduShih-Han Wang wangsh@vt.eduHan Chen heeeenry@gmail.comSiwen Wang siwenw@vt.eduEmily Marx memily15@vt.eduJiamin Wang wangjiamin123@gmail.comNoushin Omidvar omidvar@vt.edu

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