Selective Alkylation of Benzene with Methanol to Toluene and Xylene Over Sheet-Like ZSM-5 with Controllable b-Oriented Length

Sheet-like ZSM-5 zeolites with varied b-axis thicknesses (92, 160, 264 and 407 nm, respectively) and equivalent Si/Al molar ratios (ca. 150) were prepared using urea as additive in the aluminosilicate gels, and studied with respect to their performance in benzene alkylation with methanol. The ZSM-5 samples have similar textural properties and acidic properties. Catalytic tests show that these catalysts exhibit comparable benzene conversions of ca. 64% at 400 ? and WHSV of 2 h(-1). The correlation between the selectivity of toluene and xylene and the ZSM-5 crystal size in the b-axis can be established. As the b axis length is decreased from 407 to 92 nm, the selectivity to toluene and xylene increases obviously from 80.3 to 87.4%, which is attributed to enhanced diffusion property of ZSM-5 zeolite. This finding provides an alternative strategy to improve the selectivity of toluene and xylene in the alkylation of benzene with methanol over ZSM-5-based catalysts.{GRAPHICAL ABSTRACT}

Automated summary

Sheet-like ZSM-5 zeolites with varied b-axis thicknesses were prepared and studied for benzene alkylation with methanol. The catalysts exhibited comparable benzene conversions and similar textural and acidic properties. Decreasing the b-axis length led to an obvious increase in the selectivity to toluene and xylene, suggesting an enhanced diffusion property of ZSM-5 zeolite.