Impact of oxygen vacancy in CuO-ZnO catalysts on the selectivity of dimethyldichlorosilane monomer in the Rochow reaction.

A close correlation between M2 selectivity and the quantities of oxygen vacancies of catalysts is observed that the appropriate concentration of oxygen vacancies on its surface can not only promote the adsorption of gaseous CH 3 Cl molecules, but also optimizes the electronic structure of surface CuO thereby optimizing the adsorption strength of CH 3 Cl, and its porous structure can accelerate the subsequent diffusion of generated Cu atoms, thus contributing to the formation of more Cu x Si active intermediate and ultimately leading to the best M2 selectivity. [Display omitted] • The effect of oxygen vacancies (O V) in the CuO-ZnO catalysts on catalytic performance in Rochow reaction is investigated. • An optimized O V concentration of the catalyst can lead to the highest dimethyldichlorosilane selectivity. • The enhanced selectivity is attributed to the more CH 3 Cl adsorption sites and an optimized surface CuO electronic structure. In metal oxides, oxygen vacancies (O V) are ubiquitous and intrinsic defects that can pronouncedly impact the physicochemical properties of the catalysts. In this work, we investigated the effect of the O V concentration in CuO-based catalysts on the performance of the Rochow reaction. A series of foamed CuO-ZnO composite catalysts with a highly porous structure were synthesized by a facile co-precipitation method, followed by hydrogen reduction at different times. When used in the Rochow reaction to synthesize dimethyldichlorosilane (M2), the CuO-ZnO-20 catalyst with an appropriate O V concentration exhibited the highest M2 selectivity at a similar Si conversion level of the other CuO-ZnO catalysts with different O V concentrations. By correlating the structure and performance of the catalysts, we found that the O V at an appropriate concentration in CuO-ZnO-20 acted as the adsorption sites for the reactant CH 3 Cl molecules, and generated an optimized electronic structure for surface CuO as confirmed by the X-ray photoelectron spectroscopy analysis (XPS), thereby optimizing the adsorption strength of CH 3 Cl and ultimately promoting the formation of alloyed CuxSi active phase. This work provides an effective strategy for designing heterogeneous catalysts with high selectivity by controlling the O V concentration in the catalysts. [ABSTRACT FROM AUTHOR]