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

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 Brønsted 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=.