Concerted mechanisms in heterogeneous catalysis by sulfides

Abstract

This paper summarizes some new evidence for the possibility of concerted mechanisms in the heterogeneous catalysis by sulfides. Several aspects are discussed: main regularities of thiophene and THT hydrogenolysis mediated by the well-characterized sulfide catalysts of different composition; electronic structure of the metals entering into the composition of the active component of both bulk and supported sulfide catalysts; mechanism of the active centers formation cased by the oxidative addition of dihydrogen to the active Ni (Co) metals and occlusion of hydrogen atoms into the MoS 2 matrix; mechanism of the homolytic hydrogen adsorption on the sulfide hydrotreating catalysts; synchronous interaction of the reactive molecules in the coordination sphere of the bimetallic active centers — proton and electron transfer; use of the energy released during exothermic reaction steps in the catalytic cycle. Catalytic transformations over the sulfide HDS catalysts are considered to belong to the acid–base catalysis. The profound identity of the mechanisms of heterogeneous, homogeneous and enzyme catalysis is discussed.