PHOTON SCIENCE

Fernando García-Martínez, DESY researcher at the PETRA III beamline P22 Hard X-ray photoelectron spectroscopy (HAXPES), has received an “Individual Research Grant” from the DFG (Deutsche Forschungsgemeinschaft) to carry out the project “Synchrotron-based study of Ir model catalysts during operando ammonia oxidation“.

Within this research project, he will study the ammonia oxidation reaction (AOR) over different iridium (Ir) model catalysts. The oxidation of ammonia (NH₃) towards nitrogen oxide is a crucial reaction in the global fertiliser production chain, and it is carried out close to 1 bar of gas pressure in industry. This pressure is inaccessible by the vast majority of surface science techniques, making systematic investigations of model catalysts near industrial conditions difficult. In this particular case, operando studies are particularly relevant, as the AOR has three different products, namely nitrogen (N₂), nitrous oxide (N₂O) and nitrogen monoxide (NO). Only the reaction product NO is useful in the chain of fertiliser production, therefore the selectivity of the reaction must be driven towards NO. This will help to reduce production costs and support the green transition in the chemical industry.

The pressure limits of surface science experiments at the PETRA III beamlines have already been significantly expanded during the last years. In this thriving environment, Fernando García-Martínez will perform ambient-pressure hard X-ray photoemission spectroscopy (AP-HAXPES) at the POLARIS endstation of the PETRA III beamline P22, alongside complementary measurements at the surface X-ray diffraction (SXRD) at PETRA III beamline P21.2. These proposed experiments aim to fully disentangle the effect that different surface atoms (e.g. at steps or terraces) have on the surface chemistry and structure of Ir model catalysts under AOR conditions. The ultimate goal is to optimise the production oxidation of ammonia and guide the knowledge-drive design of next-generation catalysts.

“Understanding reaction mechanisms at the atomic level is of utmost importance for addressing today’s energy and climate challenges,” explains Fernando García-Martínez. “With the state-of-the-art beamlines at PETRA III, we can now study catalysts under conditions closer to those in industry, helping to tailor the development of greener and more efficient technologies. The upgrade from PETRA III to PETRA IV would offer even better opportunities for operando catalyst studies, as the higher beam intensity would allow to increase the working pressure to beyond 1 bar, enabling measurements under real industrial conditions.”