High Rate Ammonia Synthesis by Intermediate Temperature ...Ammonia Synthesis Methods We will develop...

(1) Haber-Bosch Process N2 and H2 reacting at 15–25 MPa and between 400–500°C Energy and capital intensive approach

High Rate Ammonia Synthesis by Intermediate Temperature Solid-state Alkaline Electrolyzer Storagenergy Technologies Inc.: Feng Zhao, Jared Liao and Byron Millet

Subcontractors: Iowa State University: Wenzhen Li, Yifu Chen; Pennsylvania State University: Michael Janik, Yawei Lee

Technical & Business Contact: Feng Zhao, 801-386-8555, fzhao@storagenergy.com

Introduction

Our Approach

(2) Electrochemical synthesis Low temperature, pressure, energy input, and emissions Enables networks of distributed scale and near point-of-use

Issues of Current Electrochemical Synthesis Methods

Only molten salt system operating at intermediate temperature range Low ammonia production rate due to lack of highly active NRR catalyst Low selectivity of nitrogen reduction due to HER Poor stability using liquid based and proton-conducting electrolyte

Ammonia Synthesis Methods

We will develop a game-changing intermediate temperature (100-300oC)solid-state alkaline electrolyzer (ITSAE) for high-rate ammonia productionfrom nitrogen/air and steam electrolysis based on following innovations:

(1) Cost-effective and intermediate temperature highly OH- conductingsolid membrane

Final TargetsPeriods/Parameters Phase I (Completed) Phase II (Two Years) Phase IIS (One Year)

Cell/Stack 5-cm2 single cell 5-cm2 single cell Stack

Membrane conductivity (mS/cm) >40 >100 >100

Membrane thickness (µm) ≤300 ≤50 ≤50

Current density (mA/cm2) 5.0 350 300

Coulombic Efficiency (%) ≥20 ≥94 ≥90

Ammonia production rate (mol/cm2/s) ≥3.5x10-9 ≥1.1x10-6 ≥9.4.0x10-7

Energy Efficiency (%) - >65 >60

Membrane

Acknowledgement: This project is supported by DOE ARPA-E REFUEL program (REFUEL-DE-AR0000818). We thank Drs. Grigorii Soloveichik, Julian Sculley, and Madhav Acharya.

Work Plan

Develop large ITSA membrane with thickness of ≤50 µm and ASR of ≤0.125 Ω cm2

Develop highly active and selective Fe based bimetallic oxide NRR cathode Use DFT methods to elucidate elementary reaction mechanisms and guide

catalyst design Optimize MEA and ITSAE operation conditions Demonstrate ITSAE stack with productivity of 100 g/day Techno-economic- analysis and Technology to Market

Nanosized MTP (M=Sb, Mo, V, W) powder was synthesized with high purity (except VTP). The synthesized MoTP materials exhibits highest conductivity of 87 mS/cm at 150oC. Large MoTP/PTFE composite membrane was fabricated with thickness of < 300 mm The ASR of MoTP/PTFE membrane is around 0.52 Ω cm2

NRR Catalyst

DFT calculation shows that Ni dopant facilitate N2RR in a robust way Partially reduced NiFeOx@RTO nanoparticles were fabricated as NRR catalyst ITSAE exhibited a Coulombic Efficiency of 4.54% and ammonia production rate of 3.14 X 10-9 mol/cm2/s at 150oC using

85%N2+15% H2O.

Technology to Market(1) The cost of ammonia produced by 150 MW ITSAE plant is around 0.1133$/kWh. which is 10% lower than REFUEL target

($0.128/kWh).(2) Main cost factors have been identified as electrode cost, ITSAE energy efficiency, and electricity cost.(3) Distributed ammonia production systems with productivity of 1 and 10 ton/day were selected for the first market

application.

20 30 40 50 60 70

SnP2O

7 JCPDS 29-1352

? SnO2

?

ATP

WTP

MTP

Inte

ns

ity

/ a

.u.

2 (Degree)

VTP?

0

5

10

15

20

25

30

20 mA cm-2

10 mA cm-2

5 mA cm-2

Fa

rad

aic

Eff

icie

nc

y /

%

1 mA cm-2

0.0

1.0x10-9

2.0x10-9

3.0x10-9

4.0x10-9

5.0x10-9

Ra

te /

mo

l NH

3 c

m-2 s

-1

re-NiFe/RTO, 150oC, ambient P, 15% water

TiO2

NiFe (amorphous)

Ru,Fe or Ru4Fe

MoTP/PTFE membrane

20 30 40 50 60 70 80 90

reduced NiFeOx/RTO

NiFeOx/RTO

Ru 06-0663

% %

*

%%

%

%%

Fe 06-0696

Ru4Fe 40-1147

%

&

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nsity (

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2theta (o)

RuO2 43-1027#

+ Rutile TiO2 21-1276

* Anatase TiO2 21-1272

^

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297 294 291 288 285 282 279 276

Ru4+

Ru 3d5/2

ox-NiFeOx@RTO

re-NiFeOx@RTO

Inte

ns

ity / a

.u.

Binding energy / eV

NiFeOx@RTO

C 1s

Ru0

735 730 725 720 715 710 705 700

Fe0

Fe3+

Fe 2p

Inte

ns

ity

/ a

.u.

Binding energy / eV

ox-NiFeOx@RTO

re-NiFeOx@RTO

NiFeOx@RTO

890 885 880 875 870 865 860 855 850 845

Ni 2p

Ni0

Ni2+

Inte

ns

ity / a

.u.

Binding energy / eV

NiFeOx@RTO

re-NiFeOx@RTO

Dopant Effect on Fe2O3(0001)

Ni doping

W/O doping

(2) Nanostructured Fe2O3-based bimetal oxide nitrogen reduction reaction (NRR) cathode catalyst

(3) Advanced solid composite electrode structure

(4) Noble metal-free oxygen evolution reaction (OER) anode catalyst

ASR = 0.52 Ω cm2