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

摘要

A very wide range of the C3=/C2=ratio from 0.72 to 7.56 with high C2=+ C3=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 Brφnsted acid sites favor to high C3=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 C2=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 C2=.