Deciphering the Promoting Effect of Zn on CuO for Dimethyldichlorosilane Production via the Rochow-Müller Reaction

Zinc (Zn) is commonly used as a promoter in Cu-based catalysts to boost the production of organosilane monomers during the Rochow-Müller reaction. However, the effect of Zn on the phase change of Cu-based catalysts in the reaction process is not yet fully understood. In this study, we prepared two Zn-modified CuO catalysts using simple ball milling (Zn–CuO) and physical mixing (Zn+CuO) methods. We found that adding Zn into CuO enhanced the adsorption of methyl chloride on the CuO surface, thereby promoting the sequential phase transformation of CuO to Cu₂O and then to Cu and further to CuCl. Moreover, CuCl, as a key intermediate phase, could diffuse into Si powder and form Cu₃Si under high-temperature conditions. Compared to CuO and Zn+CuO, Zn–CuO underwent a faster phase transformation, facilitating the generation of the active Cu₃Si phase and enhancing the dimethyldichlorosilane selectivity and Si conversion. This study has clarified the role of the Zn promoter in the phase transformation of CuO catalysts in the Rochow-Müller reaction. Understanding this mechanism is crucial to designing more efficient catalysts.