Mechanism on disproportionation preparation of dimethyldichlorosilane by ZSM-5(8T)@MIL-53(Al) core-shell catalyst

Dimethyldichlorosilane, which can be prepared by catalytic disproportionation synthesis of by-product chloromethylsilanes, has been the most and widely used silicone monomer. However, disproportionation reaction mechanism still needs to be explored. The mechanism of disproportionation preparation of dimethyldichlorosilane catalyzed by the core-shell catalysts ZSM-5(8T)@MIL-53(Al) and AlCl3/ZSM-5(8T)@MIL-53(Al) were calculated by using M06–2X/def2-TZVP hybrid functional method. The results showed that No. 1 active site of ZSM-5(8T)@MIL-53(Al) possessed the best catalytic performance. In detail, its rate-determining steps' activation energy values of main and side reactions were 92.64 and 125.37 kJ•mol−1, respectively. To a certain extent, the rate-determining steps’ activation energy values of main and side reactions were decreased to 81.22 and 111.41 kJ•mol−1, respectively, after loading with AlCl3. The results showed that the Lewis acid active center showed better disproportionation performance after loading.