Direct synthesis of B-axis oriented H-form ZSM-5 via solvent-free route for methanol-to-olefins reaction

A b-axis-oriented H-form ZSM-5 was synthesized for the methanol to olefins (MTO) reaction by one-step solvent-free method with the assistance of a little ammonia and urea. Urea was employed as a crystal growth inhibitor to control the b-axis orientation morphology of ZSM-5 zeolite in a solvent-free environment. Moerover, an optimal quantity of urea could facilitate the crystallization of ZSM-5 zeolite with excellent crystallinity and high phase purity. NH 4 + produced by the decomposition of urea and ammonia at high temperature replaced the traditional Na + as zeolite skeleton cations, thereby the active H-form ZSM-5 zeolite could be prepared without ammonium ion exchange or second calcination. The synthesized ZSM-5 zeolite demonstrated a extended lifetime and enhanced light olefins selectivity. It could be attributed to the suitable acidity and the b-axis oriented morphology for accelerating the mass transfer rate and shorting their residence time within the catalyst pores. • H-form ZSM-5 zeolite was synthesized directly without ion exchange by the solvent-free method. • The addition of urea effectively regulated the b-axis orientation of ZSM-5 in a solvent-free environment.