Dimethyldichlorosilane is a basic raw material for preparing a variety of organosilicon materials.The disproportionation method to synthesize it can solve the problem brought by direct synthesis.The B3LYP/6-31G and MP...Dimethyldichlorosilane is a basic raw material for preparing a variety of organosilicon materials.The disproportionation method to synthesize it can solve the problem brought by direct synthesis.The B3LYP/6-31G and MP2/6-311++G(3df,2pd) methods were used to calculate the mechanism of the reaction catalyzed by localized core(4 T)-shell catalyst.The energy barriers of the rate-determining steps of the main reaction at different active sites 1(5)~4 in the HZSM-5(4T)@γ-Al2O3 catalyst were 165.88,129.99,118.66 and 145.55 kJ·mol-1,respectively,and those in the side reaction are 131.98,146.28,146.53 and 164.17 kJ·mol-1,separately.The active site No.3 was the easiest one to participate in the catalytic reaction.The energy barriers of the rate-determining steps of the main reaction catalyzed by the AlCl3/HZSM-5(4T)@γ-Al2O3 catalyst,involving configurations a and b,are 105.12 and 110.39 kJ·mol-1,respectively,and those of the side reaction are 144.26 and 159.55 kJ·mol-1,respectively.Both configurations produced dimethyldichlorosilane mainly,and configuration a is easier to catalyze the reaction process.And according to the bond order and locality analysis,the catalytic activity order was:configuration a>configuration b.This conclusion matched with the reaction energy barrier analysis.The AlCl3/HZSM-5(4T)@γ-Al2O3 catalyst had a better catalytic activity than HZSM-5(4T)@γ-Al2O3.The active center of the reaction system of HZSM-5(4T)@γ-Al2O3 was proton,Bronsted acidic center,and that of AlCl3/HZSM-5@γ-Al2O3 could be Lewis acidic center.The source of the Lewis acidic center was the multi-center bond formed by the delocalization of peripheral electrons of the atoms.The frontier orbital theory confirmed the mechanism and good selectivity of the reaction.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 21563011 and 21872049)。
文摘Dimethyldichlorosilane is a basic raw material for preparing a variety of organosilicon materials.The disproportionation method to synthesize it can solve the problem brought by direct synthesis.The B3LYP/6-31G and MP2/6-311++G(3df,2pd) methods were used to calculate the mechanism of the reaction catalyzed by localized core(4 T)-shell catalyst.The energy barriers of the rate-determining steps of the main reaction at different active sites 1(5)~4 in the HZSM-5(4T)@γ-Al2O3 catalyst were 165.88,129.99,118.66 and 145.55 kJ·mol-1,respectively,and those in the side reaction are 131.98,146.28,146.53 and 164.17 kJ·mol-1,separately.The active site No.3 was the easiest one to participate in the catalytic reaction.The energy barriers of the rate-determining steps of the main reaction catalyzed by the AlCl3/HZSM-5(4T)@γ-Al2O3 catalyst,involving configurations a and b,are 105.12 and 110.39 kJ·mol-1,respectively,and those of the side reaction are 144.26 and 159.55 kJ·mol-1,respectively.Both configurations produced dimethyldichlorosilane mainly,and configuration a is easier to catalyze the reaction process.And according to the bond order and locality analysis,the catalytic activity order was:configuration a>configuration b.This conclusion matched with the reaction energy barrier analysis.The AlCl3/HZSM-5(4T)@γ-Al2O3 catalyst had a better catalytic activity than HZSM-5(4T)@γ-Al2O3.The active center of the reaction system of HZSM-5(4T)@γ-Al2O3 was proton,Bronsted acidic center,and that of AlCl3/HZSM-5@γ-Al2O3 could be Lewis acidic center.The source of the Lewis acidic center was the multi-center bond formed by the delocalization of peripheral electrons of the atoms.The frontier orbital theory confirmed the mechanism and good selectivity of the reaction.
