Some of the most essential catalytic reactions for our energy society is to reduce CO2 to hydrocarbons and alcohols to be used as fuels and base chemicals for the chemical industry. To convert a fossil dependent chemical industry and instead use sustainable hydrogen as a feedstock we need to develop new catalysts. Furthermore, the catalytic reduction of N2 to ammonia has been considered as one of the most important discoveries during the 20th century to produce fertilizers for a growing population. Despite an enormous effort in studying these catalytic reactions we are still lacking experimental information about the chemical state of the catalytic surface and the adsorbates existing as the reaction is turning over.

X-ray photoelectron spectroscopy (XPS) is a powerful surface sensitive technique that can provide almost all essential chemical information, and it has been developed to operate also in a few mbar of pressure with great success for probing oxidation catalytic reactions. Unfortunately, this pressure regime is too low for the hydrogenation reactions to turn over. However, utilizing the hard x-ray XPS technique can bring the pressure up by many orders of magnitude in a unique instrumentation [1].

Here I will present how Alcohol [2,3], Fischer-Tropsch [4], Methanation [5], Haber Bosch [6] reactions on single crystal metal surfaces have been probed during operando conditions in the pressure range 0.1-1 bar using the new XPS system, called POLARIS, built at Stockholm University [1] and permanently located at the PETRA III synchrotron in Hamburg at beamline P22. The instrument can vary the incidence angle of the X-rays allowing it to be either surface or bulk sensitive.

[1] P. Amann, D. Degerman, M. T. Lee, J. D. Alexander. M. Shipilin, H. Y. Wang, F. Cavalca, M. Weston, J. Gladh, M. Blom, M. Björkhage, P. Löfgren, C. Schlueter, P. Loemker, K. Ederer, W. Drube, H. Noei, J. Zehetner, H. Wentzel, J. Ålund and A. Nilsson, A High-Pressure X-ray Photoelectron Spectroscopy Instrument for Studies of Industrially Relevant Catalytic Reactions at Pressures of Several Bars Rev. Sci. Instrum.90, 103102 (2019).

[2] D. Degerman, M. Shipilin, P. Lömker, C. M. Goodwin, S. M. Gericke, U. Hejral, J. Gladh, H-Y. Wang, C. Schlueter, A. Nilsson, and P. Amann,Operando Observation of Oxygenated Intermediates during CO Hydrogenation on Rh Single Crystals, J. Am. Chem. Soc.144, 7038 (2022).

[3] P. Amann, B. Klötzer, D. Degerman, N. Köpfle, T. Götsch, P. Lömker, C. Rameshan, K. Ploner, D. Bikaljevic, H-Y. Wang, M. Soldemo, M. Shipilin, C. M. Goodwin, J. Gladh, J. H. Stenlid, M. Börner, C. Schlueter and A. Nilsson, The state of zinc in methanol synthesis over a Zn/ZnO/Cu(211) model catalyst, Science 376, 603 (2022).

[4] M. Shipilin, D. Degerman, P. Lömker, C. M. Goodwin, G. L. S. Rodrigues, M. Wagstaffe, J. Gladh, H. Y. Wang, A. Stierle, C. Schlueter, L. G.M. Pettersson, A. Nilsson, P. Amann, In situ surface-sensitive investigation of multiple carbon phases on Fe(110) in Fischer-Tropsch synthesis, ACS Catal.12, 7609 (2022).

[5] D. Degerman, P. Lömker, C. M. Goodwin, M. Shipilin, F. Garcia-Martínez, C. Schlueter, A. Nilsson, P. Amann, State of the surface during CO hydrogenation over Ni(111) and Ni(211) probed by operando x-ray photoelectron spectroscopy, J. Phys. Chem. C.127, 4021 (2023).

[6] C. M. Goodwin, P. Lömker, D. Degerman, B. Davies, M. Shipilin, F. Garcia-Martinez, S. Koroidov, J. K. Mathiesen, R. Rameshan, G. L. S. Rodrigues, C. Schlueter, P. Amann, A. Nilsson, Operando probing of the surface chemistry during the Haber-Bosch process, Nature625, 282(2024).