Inorganic cluster compounds as models for the structure of active sites in promoted hydrodesulphurization catalysts
- 1 January 1987
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 83 (7) , 2157-2167
- https://doi.org/10.1039/f19878302157
Abstract
Inorganic clusters of the type [Co(WS4)2NO]2–, [Co(WS4)(NO)2]–(PPh4 salts), [Co(MoS4)(NO)2]– and [Co(MoO2S2)(NO)2]–(NEt4 salts) have been synthesized and characterized by means of EXAFS, i.r. spectroscopy, X-ray diffraction and magnetic susceptibility measurements. By comparing these results with results for Co–Mo/Al2O3 hydrodesulphurization catalysts, a better understanding has been achieved of the structural and electronic environment of the active Co-edge promoter atoms (the so-called Co—Mo—S Co atoms) which can bind NO. The ‘adsorption complex’ in the catalyst has a pseudo-tetrahedral structure in which the {Co(NO)2S2} portion is diamagnetic and obeys the 18-electron rule. The promotional effect of Co is explained in terms of an increased electron density on the neighbouring S and Mo atoms, and analogies are made to a recent classification of the acid/base properties of the bulk sulphides.Keywords
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