Relation between Hydrogen Evolution and Hydrodesulfurization Catalysis

• Published in: ChemCatChem 2016-11, Vol.8 (21), p.3334-3337
• Main Authors: Šarić, Manuel, Moses, Poul Georg, Rossmeisl, Jan
• Format: Article
• Language: English
• Subjects: Alloys; Catalysis; density functional calculations; heterogeneous catalysis; hydrodesulfurization; hydrogen; Hydrogenation; Metals; sulfur
• ISSN: 1867-3880; 1867-3899
• DOI: 10.1002/cctc.201601014

A relation between hydrogen evolution and hydrodesulfurization catalysis was found by density functional theory calculations. The hydrogen evolution reaction and the hydrogenation reaction in hydrodesulfurization share hydrogen as a surface intermediate and, thus, have a common elementary step, which indicates that the same catalyst should perform well for both hydrogen evolution and hydrogenation. If that catalyst also fulfills additional criteria for breaking carbon–sulfur bonds and releasing hydrogen sulfide, it will be a good hydrodesulfurization catalyst. The hydrogen evolution reaction is normally performed at room temperature and standard pressure, whereas the hydrodesulfurization reaction is driven by high temperature and pressure. Owing to the very different operating conditions, the adsorption free energy of hydrogen differs between hydrodesulfurization and the hydrogen evolution reaction, which makes the connection between the two less obvious. Catalyst connections: The hydrogen evolution reaction (HER) and the hydrogenation reaction during hydrodesulfurization (HDS) share adsorbed hydrogen as a surface intermediate and, thus, have similar catalyst requirements in terms of binding hydrogen. This is why the same catalyst often works for both processes, but because the reactions are performed under different conditions, the connection is less obvious. HDS is favored by a stronger binding of hydrogen compared to the HER.