Flexible regulation of C3^=/C2^= ratio in methanol-to-hydrocarbons by delicate control of acidity of ZSM-5 catalyst

摘要

Avery wide range of the C_3~=/C_2~= ratio from 0.72 to 7.56 with high C_2~= + C_3~= selectivity of around 66%in the methanol-to-hydrocarbons process can be realized over ZSM-5 catalyst in a fixed-bed reactor.We firstly conduct a single factor experiment of acidity,demonstrating that the acidity control of MTH catalyst is crucial to adjusting light olefins selectivity.Weak Br(?)nsted acid sites favor to high C_3~= selectivity(59.0%)due to the suppression of the conversion reactions from the alkene-based to arene-based cycle,while Lewis acid sites conduce to high C_2~= selectivity(39.6%) due to the promotion of the conversion reactions for the aromatics formation and steric constraints of Lewis acid sites making the aromatics crack more efficiently to C_2~=.