Boron-modified ZSM-5 coated on honeycomb monolith surface for selective production of propylene from methanol

A promising structured catalyst was developed through proper coating of boron-modified ZSM-5 using SiO₂ and Al₂O₃-containing binders to investigate catalytic performance as well as mechanical stability of the catalyst in a monolithic reactor. The reference and boron-modified ZSM-5 catalysts were synthesized by hydrothermal route. The adherence strength of catalyst samples was characterized using ultrasonic vibration method and FESEM analysis. A series of comparative performance tests were also conducted in two reactors, including monolithic and extruded catalysts for the production of propylene from methanol at atmospheric pressure, reaction temperatures of 500 °C, and methanol weight hourly space velocity (WHSV) of 1.5 h⁻¹. Initial findings demonstrate that applying the B-modified ZSM-5 zeolite in a monolith reactor increased propylene selectivity by about 26% compared to the conventional extruded ZSM-5 catalyst. Moreover, silica bonded to the B-ZSM-5 catalyst in the monolithic reactor, owning sufficient adhesion properties; the proposed catalyst showed the best catalytic performance, with not only a high propylene selectivity (58.5%) but also a large propylene/ethylene (P/E) ratio (8.6). The findings attained in this work would be useful in the production of new efficient catalysts based on a zeolite-coated honeycomb monolith in the methanol-to-propylene process.