Hierarchical ZSM-5 Zeolite Synthesized by an Ultrasound-Assisted Method as a Long-Life Catalyst for Dehydration of Glycerol to Acrolein

This paper presents a facile and economical route to synthesizing hierarchical porous ZSM-5 zeolite (HP-ZSM-5) by an ultrasound-assisted method as a long-life catalyst for the glycerol dehydration reaction, which is an important reaction for the sustainable production of acrolein from biobased glycerol. The systematic characterizations indicate that the HP-ZSM-5 catalyst possesses large intracrystal mesopores and abundant accessible acid sites. The ultrasonic treatment and violent stirring play a critical role in the synthesis process. Compared with commercial ZSM-5 zeolite (C-ZSM-5), the turnover-frequency value at time zero of the HPZSM-5 catalyst increased nearly 1 times, and the lifetime of the HPZSM-5 catalyst was prolonged 9 times. The HP-ZSM-5 catalyst exhibits a slower coking rate with higher coke tolerance, the coke preferentially form inside the intracrystal mesopores, and the ratio of hardly removed graphitic carbon is lower than that of C-ZSM-5. The HP-ZSM-5 catalyst exhibits prominent stability of nearly 50 h and a high acrolein selectivity of 82%.