Benzylation of benzene and other aromatics by benzyl chloride over mesoporous AlSBA-15 catalysts

Abstract

Aluminum-containing mesoporous molecular sieves AlSBA-15 with different nSi/nAl ratios and AlMCM-41 have been synthesized hydrothermally and characterized in detail by physicochemical methods, viz. XRD, N2 adsorption and 27Al NMR spectroscopy. The low angle XRD and N2 adsorption measurements reveal that the structural order of SBA-15 was retained after the incorporation of Al. The increase of the unit cell parameter with increasing aluminum content and 27Al MAS NMR spectroscopy confirm the incorporation of aluminum in the framework. Benzylation of benzene and substituted benzenes reaction employing benzyl chloride as the alkylating agent over AlSBA-15 and AlMCM-41 have been investigated. The influence of various reaction parameters such as reaction temperature, reactant feed ratio and catalyst amount affecting the activity and selectivity of AlSBA-15, have been studied. Among the mesoporous catalysts studied, AlSBA-15(45), where the number in parentheses indicates the molar nSi/nAl ratio, shows both high conversion and high selectivity for the benzylation of benzene. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene > toluene > p-xylene > mesitylene > anisole. Kinetics of the benzene benzylation over different catalysts have also been investigated.