Dimethyldichlorosilane, which is the most important organic silicon monomer, can be prepared by using a novel core-shell catalyst. However, the redistributed mechanism is still a debate. In this research, the...
The redistribution method plays an important role in addressing the
issue of organosilicon by-product in the direct synthesis of
dichlorodimethylsilane, and the redistribution mechanism is still a
topic of debate. The redistribution by ZSM-5(3T)@γ-Al2O3 core-shell
catalyst and post-modified AlCl3/ZSM-5(3T)@γ-Al2O3 catalyst was
technically performed using the Density Functional Theory (DFT) at the
level of B3LYP/6-311++G(3df,2pd). The result shows that No.1 active site
of ZSM-5(3T)@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 Al-O-H bond, which is an obvious
catalytic active center of Bronsted acid. Furthermore, post-modified
AlCl3/ZSM-5(3T)@γ-Al2O3 catalyst is in more favor of redistribution
reaction comparing with ZSM-5(3T)@γ-Al2O3 core-shell catalyst. It
ascribes to the robust Lewis site of aluminum chloride favorable
modification.
Dimethyldichlorosilane is one of the most widely used monomers in the organic silicon industry chain. In the preparation process, it can be obtained by exchanging functional groups through disproportionation reaction. In this research, the disproportionation mechanism catalyzed by ZSM-5(4T)@MIL-53(Al) and AlCl3/ZSM-5(4T)@MIL-53(Al) core-shell catalysts was studied by using the density functional theory on the level of M06-2X/Def2-TZVP. The results showed that the two catalysts possessed different catalytic effect assigning to different acidic actives. The surface activity of ZSM-5(4T)@MIL-53(Al) core-shell catalyst modified by AlCl3 became the Lewis acid center of Al-Cl bond, which had better disproportionation activity than that before modification. Energies, frequency vibrations and IRC calculations, bond orders, ELF and LOL analyses can verify the reaction mechanism proposed in this research.
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