Active Sites on Nickel‐Promoted Transition‐Metal Sulfides That Catalyze Hydrogenation of Aromatic Compounds

• Published in: Angewandte Chemie International Edition Vol. 57; no. 44; pp. 14555 - 14559
• Main Authors: Luo, Wanqiu, Shi, Hui, Schachtl, Eva, Gutiérrez, Oliver Y., Lercher, Johannes A.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 26.10.2018
• Edition: International ed. in English
• Subjects: active sites; Aromatic compounds; Hydrogen storage; Hydrogenation; Metal sulfides; Metals; Molybdenum disulfide; Nickel; Slabs; Sulfhydryl groups; Sulfide; Sulfides; transition-metal sulfides; Tungsten disulfide; active sites; nickel; aromatic compounds; hydrogenation; transition-metal sulfides
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201808428

Hydrogenation on Mo and W sulfides occurs at the edges of the sulfide slabs. The rate of hydrogen addition is directly proportional to the concentration of sulfhydryl (SH) groups at the slab edge and the metal atom attached to it. Sulfhydryl groups vicinal to edge‐incorporated Ni hydrogenate with much higher rates than SH close to Mo and W. Each subset of SH groups, however, exhibits nearly identical intrinsic activity and selectivity, independent of the sulfide composition. The higher activity of Ni‐WS2 compared to Ni‐MoS2 stems from a higher concentration of SH groups on the former sulfide associated with a higher tendency of its surface vacancies to react with H2. Distinct active sites on MoS2 and WS2 consisting of accessible Mo or W cations and SH groups at the slab edge have been identified. Addition of Ni on both sulfides generates a Ni‐(SH)x site that is significantly more active than the sites associated with Mo or W and has a distinct regioselectivity for H‐addition. For all sites the ratio between the metal cation and the SH groups is constant.