Dual-templated synthesis of Si-rich [B]-ZSM-۵ for high selective light olefins production from methanol

Methanol dehydration is a high potential route for the production of light olefins (C۲-C۴). In this study, hierarchical Si-rich [B]-ZSM-۵ catalysts (Si/Al= ۲۰۰) were prepared through one-pot hydrothermal synthesis, including boron as a promoter and ethanol as a low-cost secondary template. N۲ adsorptiondesorption, XRD, FE-SEM, and FT-IR techniques were applied to characterize the catalysts. The effect of different amounts of ethanol and different operating conditions was studied on the ZSM-۵ catalyst preparation and performance in methanol-to-olefins (MTO) reaction. The results showed that the optimum amount of ethanol (ethanol/TPABr=۵) led to the highest crystallinity (۹۱.۲%), the highest specific surface area (>۴۰۰ m۲g-۱), and total pore volume (۰.۱۹ cm۳g-۱). The best catalytic performance was obtained at temperature of ۴۸۰°C and methanol hourly space velocity (WHSV) of ۷.۲ h-۱. The optimum catalyst had the highest propylene selectivity (۵۸%) and light olefin selectivity (۸۵%). The results proved the high capability of the new strategy for the efficient and fast development of the MTO catalyst.

Keywords:

Methanol to olefin , ZSM-۵ , dual template , ethanol , catalyst