Mechanism on redistribution synthesis of dichlorodimethylsilane by AlCl₃/ZSM-5(3T)@γ-Al₂O₃ core-shell catalyst

The redistribution method plays an important role in addressing the issue of organosilicon by-products in the direct synthesis of dichlorodimethylsilane, and the redistribution mechanism is still a topic of debate. The redistribution mechanism by the ZSM-5(3 T)@γ-Al₂O₃ core-shell catalyst and post-modified AlCl₃/ZSM-5(3 T)@γ-Al₂O₃ catalyst was technically performed using the Density functional theory (DFT) at the level of B3LYP/6-311 +  + G(3df,2pd). The results show that no. 1 active site of ZSM-5(3 T)@γ-Al₂O₃ core-shell structure has a significant effect on the activity of the catalyst. Indicating that the active center involved in the reaction is H provided by the Al-O-H bond, which is an obvious catalytic active center of Bronsted acid. Furthermore, the post-modified AlCl₃/ZSM-5(3T)@γ-Al₂O₃ catalyst is in more favor of redistribution reaction comparing with the ZSM-5(3 T)@γ-Al₂O₃ core-shell catalyst. It ascribes to the robust Lewis site of aluminum chloride favorable modification. The redistribution synthesis mechanism of dichlorodimethylsilane on the ZSM-5(3 T)@γ-Al₂O₃ core-shell catalyst and post-modified AlCl₃/ZSM-5(3 T)@γ-Al₂O₃ catalyst had been investigated by using the Density functional theory (DFT) method at the level of B3LYP/6-311 +  + G(3df,2pd). The former active center was Bronsted acidic center, while the latter one was Lewis acidic center, ascribing to the Lewis site of aluminum chloride favorable modification. The catalytic activity of the post-synthesis AlCl₃/ZSM-5(3 T)@γ-Al₂O₃ catalyst completely was consistent with experimental results.