Catalytic synergy between the low Si/Al ratio Zn/ZSM-5 and high Si/Al ratio HZSM-5 for high-performance methanol conversion to aromatics

Rational mixing of two kinds of catalysts with catalytic coupling functions could efficiently convert reactants to products via two successive steps. Herein, high Si/Al ratio ZSM-5 (Z220) was mixed with low Si/Al ratio Zn/ ZSM-5 (ZnZ30) for two-step methanol conversion to aromatics (MTA). Sufficient experiments explored their catalytic synergy and found that methanol was firstly converted into light hydrocarbons on Z220, and then light hydrocarbons were converted into aromatics on neighboring ZnZ30. ZnZ30 not only catalyzed light alkenes into aromatics, but also catalyzed light alkanes to light alkenes and then to aromatics. Changing mixing ratio controlled the proportions of two steps for MTA reaction and achieved a good match between two processes, which increased aromatic selectivity from 30.3%-39.9% and prolonged lifetime by a factor of 10 compared with one-step aromatization. Optimizing reaction temperature, Si/Al ratio and granule size of catalysts further strengthened their catalytic synergy for improved catalytic performance.

Automated summary

Mixing high Si/Al ratio ZSM-5 with low Si/Al ratio Zn/ZSM-5 catalysts efficiently converts methanol to aromatics in two steps, enhancing aromatic selectivity and prolonging catalyst lifetime. Optimizing reaction conditions further improves catalytic performance through catalytic synergy.