Friedel-Crafts alkylation of toluene with methyl mercaptan has been investigated in the presence of H-ZSM-5 and SiO2/H-ZSM-5 catalysts. The silica layers have been built on H-ZSM-5 zeolite by chemical liquid deposition of tetraethyl orthosilicate. The passivation with silica of the external surface of H-ZSM-5 zeolite has been confirmed by FT-IR spectroscopy and mesitylene isomerization, used as a model reaction. All catalysts exhibited notable behavior in the alkylation of toluene to xylenes. Efficiencies higher than 98 % in alkylation for both toluene and methyl mercaptan were obtained at 375 °C. In terms of para-selectivity, outstanding performance was revealed by the silylated zeolites. Thus, over 12 % SiO2/H-ZSM-5, at 375 °C and WHSV = 9.4 gtoluene+CH3SH gcat-1h−1, the para-xylene selectivity was close to 100 %. The experimental apparent activation energy for the toluene alkylation with methyl mercaptan catalyzed by H-ZSM-5 was 80 kJ/mol.

中文翻译：

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甲硫醇对硅烷基化 ZSM-5 分子筛进行甲苯的高对位选择性烷基化反应


已在 H-ZSM-5 和 SiO2/H-ZSM-5 催化剂存在下研究了甲苯与甲硫醇的 Friedel-Crafts 烷基化反应。二氧化硅层是通过正硅酸四乙酯的化学液体沉积在 H-ZSM-5 沸石上构建的。H-ZSM-5 沸石外表面的二氧化硅钝化已通过 FT-IR 光谱和均三甲苯异构化证实，用作模型反应。所有催化剂在甲苯烷基化为二甲苯的过程中都表现出显著的行为。在 375 °C 下，甲苯和甲硫醇的烷基化效率均高于 98 %。 在对位选择性方面，硅烷化沸石表现出出色的性能。因此，在 375 °C 和 WHSV = 9.4 gtoluene+CH3SH gcat-1h-1 下，超过 12% 的 SiO2/H-ZSM-5，对二甲苯选择性接近 100%。H-ZSM-5 催化甲硫醇与甲苯烷基化反应的实验表观活化能为 80 kJ/mol。