Diffusion-controlled synthesis of Cu-based catalysts for the Rochow reaction

The properties of materials are strongly dependent on their structures. The diffusion effect is a main kinetic factor that can be used to regulate the growth and structure of materials. In this work, we developed a systematic and feasible strategy to synthesize Cu 2 O solid spheres and hexahedrons by controlling the diffusion coefficients. These Cu 2 O products can be successively transformed into corresponding Cu hollow spheres and hexahedrons as well as CuO porous spheres and hexahedrons by controlling hydrogen diffusion in hydrazine hydrate solution and controlling oxygen diffusion in air, respectively. The formation of these transformations was also discussed in detail. Tested for Rochow reaction, the as-prepared Cu 2 O solid and CuO porous spheres exhibit higher dimethyldichlorosilane selectivity and Si conversion than Cu hollow spheres, which is attributed to the active sites for CH 3 Cl adsorption formed in Cu x Si phase after the removal of oxygen atoms in Cu 2 O and CuO in the formation of dimethylchlorosilane. The present work not only develops a feasible method for preparing well shape-defined Cu 2 O solid spheres and hexahedrons but also clarifies the respective roles of Cu, Cu 2 O and CuO in dimethyldichlorosilane synthesis via Rochow reaction.