Activity of Gallium and Aluminum SBA-15 materials in the Friedel-Crafts alkylation of toluene with benzyl chloride and benzyl alcohol

摘要

Ga-, Al- and AlGa-SBA-15 mesoporous materials were synthesized via a direct sol-gel hydrothermal protocol. The SBA-15 materials were characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), N2 physisorption, transmission electron microscopy (TEM) and pyridine and 2,6-dimethylpyridine titration. The activity of the Ga- and AlGa-SBA-15 was investigated in the Friedel-Crafts alkylation of toluene with benzyl chloride (promoted by Lewis acidity) and benzyl alcohol (promoted by Bronsted acidity). Quantitative conversion of the starting material was found for all Ga- and AlGa-SBA-15 after a few hours of reaction at 110 °C in the alkylation of toluene with benzyl chloride. The mesoporous acidic materials provided very poor activities in the alkylation of toluene with benzyl alcohol, with the exception of the Al-SBA-15. The activities of the Ga- and AlGa-SBA-15 were correlated to the higher proportion of Lewis compared to Bronsted acid sites. The solid acids were also highly reusable preserving almost their initial catalytic activity after five reuses.