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Advance Science. Applied Technology
Hydrocarbon Storage Simulation in Rhodium Software and
Validation via Reactor Testing
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Presented By:
Minnie LahotiEngineer
Southwest Research Institute
Overview
• Rhodium - Background• Rhodium Application
• Simulation Results• Experimental Plan• Results & Discussion• Summary – Rhodium Validation
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Rhodium – A Protein Docking Software
• Performs Unbiased, Traceable Small Molecule Docking Simulations Over Proteins
• Verified Application• Drug delivery optimization• Protein engineering
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• Apply Concept to HC Storage in Zeolites for Automotive Industry• HC storage in DOCs during
cold start• HC storage: physical process– Match between HC size
and zeolite pore size
Preface - Simulation
• Explore Thermodynamic Modeling Capabilities of Rhodium• Understand Shortcomings – Address in Future Work• Predict Performance of Zeolites in Adsorption and Desorption
of Hydrocarbons (HC)• Select a Series of Zeolites Widely Used in Automotive
Industry• Conduct HC Storage Simulations on Selected Zeolites
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Structure-Based Modeling: Decane in ZSM-5
• Crystal Lattice Of Zeolite Represented By 3x3x3 Unit Cells, Or 27 Total
• Low & High Resolution Pose Search• HCs Added ~5 Molecules/Unit Cell
• Rhodium Assumes no Reaction Between Zeolite & HC• Purple: Searching Sites for Potential Docking
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Progression of Dodecane Occupying a Zeolite
• Cavity Occupancy Score (CAVOC)• 2nd Dodecane Affinity Near 1st
Molecule• Increased van der waals forces
• Sodalite and Supercages Fill with Dodecane• Dodecane occupy different sections of
zeolite
• Excellent Visual Representation of Zeolite and HC Interaction
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Simulation Example
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• Decane Packing in High SiO2/Al2O3 ZSM-5 Cavity-Occupancy Pose and Scores• CAVOC Score Highest for Dodecane
Simulation Details
• 10 HCs chosen from Advanced Combustion Catalyst & Aftertreatment Technology (AC2AT) Emission Characterization Consortium
• HCs simulated were C1-C12 • Methane, Ethene, Propene, Propane,…,Dodecane
• Models Of 25 Zeolite Types Were Used In The Simulations• Zeolites To Be Wash Coated Were Selected Based On
Simulated Selectivity, Commercial Availability, Thermal Stability
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Simulation Results
• Various Zeolite Structures Simulated with 10 Different Sized HCs (Methane to Dodecane)• Choose Zeolites with the Highest Selectivity for Light HCs,
Heavy HCs and Varying SiO2/Al2O3 ratio (high and low end)• Simulations Are More Efficient Than Experimentally Deriving
Results
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Simulation Results
• Based on the Simulation Results and the Availability of Zeolites, the Following Were Used to Wash-Coat Catalyst Cores:
• MFI-ZSM-5 (low SiO2/Al2O3 ratio ~15-45)• MFI-ZSM-5 (high SiO2/Al2O3 ratio ~371)• CHA-SSZ-13 (light HC storage)• MTW-ZSM-12 (heavy HC storage)
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MFIMTW
CHA
http://asia.iza-structure.org/
Simulation Results
• Simulation Results Shown For Idealized Zeolite Structures• ZSM-5 With High SiO2/Al2O3 Ratio Shows Highest Selectivity
For Most HCs
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Preface - Experimental
• Wash Coat Catalyst Cores with the Best Zeolite Candidates • Evaluate HC trapping efficiency via Automated Universal
Synthetic Gas Reactor (USGR®) system • HCs chosen from Advanced Combustion Catalyst &
Aftertreatment Technology (AC2AT) emission characterization project
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USGR®
Experimental Plan
• Zeolite/Binder Slurry Preparation• Zeolite sieved through 180 µm mesh• Powder dissolved in DI water – 0.2 g/mL • Nyacol Alumina Binder Solution Added to Slurry With 1:10
Binder To Water Ratio• Stir For At Least Half Hour Before Wash-coating
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Experimental Plan
• Catalyst Preparation• Pre-Calcined Monoliths Dipped in Slurry• Excess Slurry Removed via Compressed N2
• Placed Horizontally in the Oven at 200 °C for 20 min• Process Repeated Until ~1 g/cm3 Zeolite Loading Achieved
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Experimental Testing via USGR®
• HC Mixture Simulated • Capability to Inject Liquid HCs With Fast Response Time • Storage Testing Conducted at 100 °C• S.V. 60,000 hr-1
• Gas Concentrations Measured Via FTIR
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T = 100 °C
Dodecane
Dodecane Storage
Time (s)Co
ncen
tratio
n (p
pm)
Catalyst Characterization
• BET Surface Area and SEM Images
• Understand uniformity of washcoating
• High ZSM-5 washcoatedpoorly
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Zeolite BET Surface Area (m2/g)
SSZ-13 74.92ZSM-5 High SiO2/Al2O3
43.77
ZSM-5 Low SiO2/Al2O3
59.52
ZSM-12 34.07
Low ZSM-5 SSZ-13
High ZSM-5 ZSM-12
Experimental Storage Results
• ZSM-5 Superior To All Other Catalyst – Results Match Simulation
• MFI Zeolite Structure Selective for Dodecane and Decane
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Storage Results
• ZSM-12 vs. SSZ-13• Prediction: ZSM-12 Better for Heavy HC, SSZ-13 Light HC• Storage Testing Confirms Prediction
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Storage Results
• Low vs. High SiO2/Al2O3 Ratio – ZSM-5• High ZSM-5 Superior • High SiO2/Al2O3 Ratio Allows Greater Acid Sites for HC
species Interaction with Surface
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Simulation vs. Test Results
• Selectivity Trend Predicted Correctly But Not Quantitatively
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Simulation vs. Test Results
• Propene Storage Not Predicted• Reactivity not predicted in Rhodium
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Conclusions
• 4 Zeolites Chosen Based on Simulations & Availability• MFI-ZSM-5 (low SiO2/Al2O3 ratio)• MFI-ZSM-5 (high SiO2/Al2O3 ratio)• CHA-SSZ-13 (light HC storage)• MTW-ZSM-12 (heavy HC storage)
• Simulation and Test Results Confirm ZSM-5 High Superior • Excellent Visual Tool For HC and Zeolite Interaction• Simulations Conducted in 3 to 4 weeks• DFT Simulations – 3 to 6 months• Experimental Testing – 6 months to over a year
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Future Work
• Incorporate New Features into Rhodium Software• Discrepancy Between Simulations and Test Results• Simulations do not account for chemistry• Propene reactivity not accounted for• Simulations do not have a flow direction• No ability to provide space velocity variations• Lack of crystallography on tested materials• Lack of zeolites with required SiO2/Al2O3 Ratio
• Combination of Zeolites for Improved HC Storage
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Future Work
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Zeolite
Zeolite + PGM
NOX SCR
• Change Type of Zeolite, Counterion
• Look at Reduction and Oxidation Reactions Based on Lewis Acid and Bronsted Acid Sites
• Apply Concepts to Predict NOX-SCR Catalyst Reactions
Acknowledgement
• Dr. Jonathan Bohmann – Rhodium Software• Southwest Research Institute – Funding Internal Research • Dr. Cary Henry – Assistant Director• Dr. William Epling, Dr. Yasser Jingjou, Kevin Gu – University of
Virginia• Team Members:• Dr. Robert Henderson – Research Engineer• Chris Sharp – Staff Engineer• Scott Eakle – Principal Engineer• Bryan Zavala – Engineer• Seth Brenneman – Research Engineer• Ryan Hartley – Graduate Student• Nate Martinez – Senior Technician
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