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

Abstract

Abstract 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.