High-efficient hierarchical [B]-ZSM-5 catalyst by simultaneously using of CTAB surfactant and boron promoter for methanol to olefins reaction

Abstract

In this work, a one-pot hydrothermal route was applied to prepare the hierarchical high-silica ZSM-5 catalyst (Si/Al = 200), including boron promoter in the structure and CTAB surfactant. XRD, FE-SEM, BET, NH3-TPD, and FT-IR techniques were applied to evaluate the physical and chemical properties. The effect of different amounts of secondary template (CTAB) and different operating conditions was studied on the ZSM-5 catalyst preparation and performance in methanol to olefins reaction. The results showed the high surface area (391.8 m2g−1), mesoporous structure, high crystallinity, and well-adjusted acidity for the modified catalyst. The prepared catalyst with CTAB/TPABr molar ratio of 1 led to the highest propylene selectivity (48.56%), the highest P/E ratio of 6.3, and the highest light olefin selectivity (71%). This improved performance can be assigned to the high surface area, short diffusion path length by mesopore structure, and optimum acidity. It was found that the optimum temperature and weight hourly space velocity were 480 °C and 7.2 h−1, respectively.