electrochemical ammonia synthesis · 2021. 2. 16. · ammonia. science advances4, no. 4 (april...

Nitricity

Nitricity produces distributed nitrogen fertilizer using only air, water, and renewable electricity.

Nitricity in action | team

3

Notable Awards

Jay Schwalbe Josh

McEnaney

Nico Pinkowski

Nitricity in action | on-farm system

4

Notable Awards

Jay Schwalbe Josh

McEnaney

Nico Pinkowski

Nitricity in action | on-farm system

5

Notable Awards

Jay Schwalbe Josh

McEnaney

Nico Pinkowski

Nitricity report 2020 growing season

Solar + Agriculture

6

Jay Schwalbe Josh

McEnaney

Nico Pinkowski

India is pushing 31 GW of solar to help farmers offset pumping and electrical needs

Low soil resilience in China

Poor soil in Africa and South America

8

We need to double food production by 2050, but we have finite resources!

9

Incumbent technology

Pattabathula, Venkat, and Jim Richardson. “Introduction to Ammonia Production.” Back to Basics, 2016, 7.

Haber-Bosch:400 ̊C, 200 atm

N2 + 3H2 ⇌ 2NH3

Incumbent technology - distribution


N2 + 3H2 ⇌ 2NH3

Galloway, James N., and Ellis B. Cowling. “Reactive Nitrogen and The World: 200 Years of Change.” AMBIO 31, no. 2 (March 2002): 64–71.

Vegetarian

Carnivorous

14% N used

4% N used



N2 + 3H2 ⇌ 2NH3

Galloway, James N., and Ellis B. Cowling. “Reactive Nitrogen and The World: 200 Years of Change.” AMBIO 31, no. 2 (March 2002): 64–71.

53% N lost in distribution and to runoff


Incumbent technology - distribution

N2O emissions

Appendix

CALIFORNIA AGRICULTURE • VOLUME 71, NUMBER 3

N2O emitted from microbial activity in both ammonia oxidation (nitrification) and nitrate reduction (denitrification)

Excess N increases emissions

Low oxygen increases denitrification

High frequency application has been shown to reduce N2O

https://www.sciencedirect.com/science/article/abs/pii/S0167880916303954?via%3Dihub, Scientific RepoRts | 6:30349 | DOI: 10.1038/srep30349

https://www.sciencedirect.com/science/article/abs/pii/S0167880916303954?via%3Dihub

Production1.4% of global CO2

Distribution0.07% of global CO2

Application6.1% of global CO2eq

Farmers pay 3x-5x gate cost

Centralized, extreme CapEx

14

Ineffective nutrient management

Problems that require breakthrough solutions

Production1.4% of global CO2

Distribution0.07% of global CO2

Application6.1% of global CO2eq

Farmers pay 3x-5x gate cost

Centralized, extreme CapEx

15

Ineffective nutrient management

Problems that require breakthrough solutions

2.88 Gt CO2eq

High $/acre

Potential for Electrification

1% efficient

100% efficient

Solar cell area required for NH3

synthesis (blue) is strongly dependent on efficiency.

approach Cell

potenti

al [V]

Faradaic

effecien

cy

kWh/kg

NH3

Haber-bosch +

water splitting1

NA NA 18.3

Electrochemical

limit

1.23 100 6.9

Low FE

electrochemical

1.23 1 690

High

overpotential

4 100 22.4

1Cussler, Edward et. al. “Ammonia Synthesis at Low Pressure.” JoVE no. 126 (August 23, 2017): e55691.

Electrochemistry – a possible distributed competitor

N2 + 6H+ + 6e- ⇌ 2NH3


V

N2 + 6H+ + 6e- ⇌ 2NH3

cathodeanode


V

N2 + 6H+ + 6e- ⇌ 2NH3

electrolyte

Ions (H+)

electrons

cathodeanode


N2 + 6H+

2NH3

V

6e-

N2 + 6H+ + 6e- ⇌ 2NH3

cathodeanode


N2 + 6H+

2NH3

3 H2O

3/2 O2 + 6H+

6e-

V

6e-

N2 + 6H+ + 6e- ⇌ 2NH3

cathodeanode

Basic Definitions

N2 + 6H+

2NH3

3 H2O

3/2 O2 + 6H+

6e-

V

6e-

N2 + 6H+ + 6e- ⇌ 2NH3

Faradaic Efficiency = 𝐶ℎ𝑎𝑟𝑔𝑒 𝑡𝑜 𝑁𝐻3

𝑇𝑜𝑡𝑎𝑙 𝐶ℎ𝑎𝑟𝑔𝑒

cathodeanode

The Voltage Determines the Driving Force

N2 + 6H+

2NH3

3 H2O

3/2 O2 + 6H+

6e-

V

6e-

N2 + 6H+ + 6e- ⇌ 2NH3



Volts [J/C]1.230

Hydrogen EvolutionReaction(pH=1) (HER)

Oxygen EvolutionReaction (OER)

cathodeanode


N2 + 6H+

2NH3

3 H2O

3/2 O2 + 6H+

6e-

V

6e-

N2 + 6H+ + 6e- ⇌ 2NH3



Volts [J/C]1.230

Nitrogen Reduction (N2RR)0.09 v. HER

HEROER

cathodeanode


N2 + 6H+

2NH3

3 H2O

3/2 O2 + 6H+

6e-

V

6e-

N2 + 6H+ + 6e- ⇌ 2NH3



Volts [J/C]1.230

HER OER

N2RR

cathodeanode

Simplified Mechanism of Ammonia Synthesis

Singh, Aayush R., Brian A. Rohr, Michael J. Statt, Jay A. Schwalbe, Matteo Cargnello, and Jens K. Nørskov. “Strategies toward Selective Electrochemical Ammonia Synthesis.” ACS Catalysis, July 29, 2019, 8316–24.

N≡N

H+

e-

N

N

=

H+ 2H+ + 2e-

N≡

+ 3H+ + 3e-

NH3 NH3

Simplified Version of the Energetic Landscape


N≡N

H+

e-

N

N

=

H

+ 2H+ + 2e-

+ 3H+ + 3e-

N≡

NH3

NH3

EnergyMore Negative Voltage

Limiting Potential Applied

The Hydrogen evolution reaction presents a fundamental challenge


Easier

HER

Nitrogen Reduction

1% faradaic efficiency

100% faradaic efficiency

Solar cell area required for NH3

synthesis (blue) is strongly dependent on faradaic efficiency.

DFT Gives us a Starting Point


HER

Nitrogen Reduction

H

H+N2

H H HHH

e-

Catalyst Surface

Even the Most Exciting Cases Don’t Work in Water

Jay Schwalbe, unpublished dataAndersen et. al. nature 1, 2019

H

H+N2

H H HHH

e--0.01

0.01

0.03

350 550 750

abso

rban

ce

Wavelength [nm]

N2RRconditions

Negative control

FE<1% - Not Statistically Significant

Catalyst Surface

Even the Most Exciting Candidates Don’t Work in Water

Jay Schwalbe, unpublished dataAndersen et. al. nature 1, 2019

H

H+N2

H H HHH

e--0.01

0.01

0.03

350 550 750

abso

rban

ce

Wavelength [nm]

N2RRconditions

Negative control

FE<1% - Not Statistically Significant

Catalyst Surface

Model Development


H

H+

H H HHH

𝑟𝐻 = 𝑘𝐻𝜃𝐻 ǁ𝑐𝐻+ ǁ𝑐𝑒− ≅ 𝑘𝐻 ǁ𝑐𝐻+ ǁ𝑐𝑒−

e-

Catalyst Surface

Model Development


Catalyst Surface

H

H+N2

H H HHH


e-

𝑟𝑁 = 𝑘𝑁𝜃𝑁2 ǁ𝑐𝐻+ ǁ𝑐𝑒− ≅ 𝑘𝑁𝐾𝑁𝐾𝐻

ǁ𝑐𝑁2

𝜃𝑁2 =𝐾𝑁 ǁ𝑐𝑁2

1+𝐾𝐻 ǁ𝑐𝐻+ ǁ𝑐𝑒−+𝐾𝑁 ǁ𝑐𝑁2≅

𝐾𝑁 ǁ𝑐𝑁2𝐾𝐻 ǁ𝑐𝐻+ ǁ𝑐𝑒−

Model Development


H

H+N2

H H HHH


e-


ǁ𝑐𝑁2

𝑟𝑁𝑟𝐻=𝑘𝑁𝑘𝐻

∗𝐾𝑁𝐾𝐻

∗ǁ𝑐𝑁2

ǁ𝑐𝐻+ ǁ𝑐𝑒−

H+

H+

H+

H+

H+

H+

H+

H+

Water has too many protons!

Catalyst Surface

Proposed Strategies




ǁ𝑐𝑁2

𝑟𝑁𝑟𝐻=𝑘𝑁𝑘𝐻

∗𝐾𝑁𝐾𝐻

∗ǁ𝑐𝑁2

ǁ𝑐𝐻+ ǁ𝑐𝑒−

Experimental Measurements of Ammonia Synthesis

Ammonia rates are observed to be low

39

N co

nta

inin

g

po

lymer

Ca

rbo

n

na

no

spikes

Ion

ic liqu

id

electrolyte

Eth

ylene

dia

min

e

“A Physical Catalyst for the Electrolysis of Nitrogen to Ammonia.” Science Advances 4, no. 4 (April 2018): e1700336.

“Ammonia Electrosynthesis with High Selectivity under Ambient Conditions via a Li+ Incorporation Strategy.” Journal of the American Chemical Society 139, no. 29 (July 26, 2017): 9771–74.

“Electro-Synthesis of Ammonia from Nitrogen at Ambient Temperature and Pressure in Ionic Liquids.” Energy & Environmental Science 10, no. 12 (2017): 2516–20.

“Electrochemical Synthesis of Ammonia from Water and Nitrogen in Ethylenediamine under Ambient Temperature and Pressure.” J. Electrochem. Soc. 163 (2016).

Ammonia rates are observed to be low

40

N co

nta

inin

g

po

lymer

Ca

rbo

n

na

no

spikes

Ion

ic liqu

id

electrolyte

Eth

ylene

dia

min

e

Low enough to be in the range of common contamination

41

Left: >5ppm ~ 275uM contamination from adhesive on vial top

N co

nta

inin

g

po

lymer

Ca

rbo

n

na

no

spikes

Ion

ic liqu

id

electrolyte

Ethylen

e d

iam

ine

Some critical literature

42

“A Re-Evaluation of Sn(II) Phthalocyanine as a Catalyst for the Electrosynthesis of Ammonia.” Electrochimica Acta 258 (December 2017): 618–22.

“Critical Assessment of the Electrocatalytic Activity of Vanadium and Niobium Nitrides toward Dinitrogen Reduction to Ammonia.” ACS Sustainable Chemistry & Engineering, February 5, 2019.

Detect ammonia with N2 supplied

Amount greater than with Argon or

no Current?

Eliminate sources of contamination

Verify with purified 15N2 experiment

43

Searle, Phillip L. “The Berthelot or Indophenol Reaction and Its Use in the Analytical Chemistry of Nitrogen. A Review.” Analyst 109, no. 5 (January 1, 1984): 549–68.

55 µM 165 µM0 µM

Ammonia detection is possible with a number of techniques -Colorimetric


44Thanks, Chenshuang Zhou!

Water


55 µM 165 µM0 µM

More NH3

Pea

k a

rea

ab

sorb

an

ce

45

Thanks, Chengshuang Zhou!

Water

Propylene Carbonate


55 µM 165 µM0 µM

More NH3

More NH3

Pea

k a

rea

Pea

k a

rea

ab

sorb

an

cea

bso

rba

nce

Wavelength [nm] uM NH3


Ammonia detection is possible with a number of techniques - NMR

46

300 µM200 µM100 µM

Selective excitation of ammonia

Nielander, Adam C., Joshua M. McEnaney, Jay A. Schwalbe, et. al. ACS Catalysis 9, no. 7 (July 5, 2019): 5797–5802.


47

300 µM200 µM100 µM


Solvent not strongly detected

Nielander, Adam C., Joshua M. McEnaney, Jay A. Schwalbe, et. al. ACS Catalysis 9, no. 7 (July 5, 2019): 5797–5802.


48

300 µM200 µM100 µM


Solvent not strongly detected



no Current?



no Current?



no Current?

Schematic of Electrochemical Experiment

49

V Gas Supply

Voltage Supply

Electrolyte:THF, 0.1M LiClO4, 1 v% EthanolMo cathode

Schematic of Electrochemical Experiment

V Gas Supply

Voltage Supply


More Protons

Tsuneto, Akira, Akihiko Kudo, and Tadayoshi Sakata. Chemistry Letters 22, no. 5 (May 1, 1993): 851–54.

H2

NH3

Fara

da

ic E

ffic

ien

cy

Schematic of Electrochemical Experiement

51

V Gas Supply

Voltage Supply


IncreasingAmmoniaa

bso

rba

nce

Wavelength [nm]

Schematic of Electrochemical Experiement

52

IncreasingAmmonia

No Ammonia Expected

ab

sorb

an

ce

Wavelength [nm]

ab

sorb

an

ce

Wavelength [nm]

NMR Has Less Baseline Variation

53

No Current, N2

Current, Ar

Current, N2

NMR Gives More Clear Results

54

No Current, N2

Current, Ar

Current, N2

V

Verify with purified 15N2 experiment



no Current?

15N labelling experiments

15N2

15NH3

14NH3

Only adventitious

Genuine

V

Contamination in 15N2

15N2

15NH3

14NH3

Only adventitious

Contamination+Genuine

15N2O

V

Contamination in 15N2

Wavenumber [cm-1]

ab

sorb

an

ce

Spectra of 15N2O

Spectra of commercial 15N2

15N2

15NH3

14NH3

Only adventitious

Contamination+Genuine

15N2O

V

“The Contamination of Commercial 15N2 Gas Stocks with 15N–Labeled Nitrate and Ammonium and Consequences for Nitrogen Fixation Measurements.” PLoS ONE 9, no. 10 (October 17, 2014): e110335.

Gas must be purified and quantitative agreement achieved

Andersen, Suzanne Z., Viktor Čolić, Sungeun Yang, Jay A. Schwalbe, Adam C. Nielander, Joshua M. McEnaney, Kasper Enemark-Rasmussen, et al. “A Rigorous Electrochemical Ammonia Synthesis Protocol with Quantitative Isotope Measurements.” Nature, May 22, 2019, 1.

Gas purification and recycling set-up at DTU




14NH3




14NH3

15NH3




14NH3

15NH3 Verify with purified 15N2 experiment



no Current?

Questions?

electrochemical ammonia synthesis · 2021. 2. 16. · ammonia. science advances4, no. 4 (april...

Documents