Elucidation of the different reaction mechanisms and pathways offered by the AOR

Projektinformationen

EluMecAOR

ID Finanzhilfevereinbarung: 101069017

DOI

10.3030/101069017

Projekt abgeschlossen

EK-Unterschriftsdatum 1 August 2022

Startdatum 1 Januar 2023

Enddatum 31 Dezember 2024

Finanziert unter

• Marie Skłodowska-Curie Actions (MSCA)

Gesamtkosten

Keine Daten

EU-Beitrag

€ 173 847,36

Koordiniert durch

MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DER WISSENSCHAFTEN EV
Germany

Periodic Reporting for period 1 - EluMecAOR (Elucidation of the different reaction mechanisms and pathways offered by the AOR)

Berichtszeitraum: 2023-01-01 bis 2024-12-31

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

The European Union aspires to achieve a greenhouse gas-free economy by 2050.1 To meet this ambitious goal, green hydrogen is considered a pivotal energy source.2 One promising method for storing hydrogen involves using ammonia as a hydrogen carrier. At 8 bar, ammonia has more than twice the volumetric energy density (10.5 MJ/L) compared to compressed hydrogen at 700 bar (5 MJ/L).3 Furthermore, with the increasing production of green ammonia via the Haber-Bosch process coupled with renewable energy sources, it becomes a viable option for hydrogen production. Companies such as Siemens Energy, BP, and ThyssenKrupp are joining efforts to enhance ammonia production in countries with abundant renewable energy resources.4-7
Consequently, readily available ammonia emerges as an excellent candidate not only for hydrogen transport but also as a standalone energy source for fuel cells. For this reason, it is crucial to understand how to electrochemically decompose ammonia to generate electrical power.
The objective of this project is to elucidate the various descriptors and mechanisms governing the ammonia electro-oxidation reaction (AOR) and to identify the chemical species produced during this reaction. This knowledge will pave the way for designing efficient catalysts to harness energy from ammonia.

1. https://ec.europa.eu/clima/policies/strategies/2050_en
2. https://ec.europa.eu/energy/topics/energy-system-integration/hydrogen_es
3. Schüth, F.; Palkovits, R.; Schlögl, R.; Su, D. S. Ammonia as a possible element in an energy infrastructure: catalysts for ammonia decomposition. Energy Environ. Sci. 2012, 5, 6278
4. Lewis, J. Origin and MOL explore shipping green ammonia from Australia from 2026(www.upstreamonline.com) August 2021
5. Paul, S. BP sees potential for green hydrogen, ammonia plant in Australia (www.reuters.com) August 2021
6. https://www.siemens-energy.com/uk/en/offerings-uk/green-ammonia.html
7. https://www.thyssenkrupp-industrial-solutions.com/power-to-x/en/green-ammonia

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

The EluMecAOR project conducted fundamental studies on the kinetics of AOR using potentiometric techniques across various temperatures. Efforts were also directed at enhancing the catalytic activity of the reaction through chemical modifications to the catalyst. Additionally, voltammetric and spectroscopic characterizations were performed under operational conditions (Raman and Q-EXAFS) to detect intermediates during the ammonia oxidation reaction.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

The findings highlight the presence of key intermediates in AOR (NH2, *NO, and *N) and underscore the critical role of the solvent in reaction kinetics. Analysis of kinetic parameters, such as activation energy and pre-exponential factor, revealed that the solvation kinetics of ions play a crucial role in AOR, much like in reactions such as HER and ORR, where hydroxide ion solvation-(de)solvation affects catalytic performance. Specifically, in AOR, the results distinguish between poisonous species (*N and *NO) that arise in parallel mechanisms at different potentials under time-dependent dynamic conditions.
Furthermore, the results show how these poisonous species influence the reaction’s activation energy and the configurational entropy of the catalyst surface. The catalytic activity of AOR also depends on the catalyst's surface charge, which varies with pH.
From a fundamental perspective, this work is pivotal for developing and designing new catalysts with high activity, stability, and selectivity, enabling the use of ammonia as an energy source in fuel cells or for synthesizing high-value chemical compounds.