Abstract
In the Müller-Rochow process or direct process, CH3Cl reacts with silicon, forming (CH3)2SiCl2 (M2) as the dominant species with copper as catalyst. This complex and highly heterogeneous process takes place in a gas-solid stirred fluidized bed reactor. In this study, the formation of (CH3)2SiCl2 on a Cu rich Cu-Si model has been investigated using density functional theory (DFT). The results show that the overall reaction is exoergic. Upon dissociation of CH3Cl, the reaction proceeds first by interaction of CH3 with Si followed by subsequent addition of Cl. The largest activation barrier is found for the second Si-Cl bond formation in which a weakly adsorbed (CH3)2SiCl2 is formed. Compared to dehydrogenation of adsorbed CH3 formed upon dissociation of CH3Cl, formation of M2 is energetically favoured on a Si modified Cu(111) model.