Ultrasound-assisted synthesis of nanosized hierarchical ZSM-5 and its catalytic performance as the support for heteropolyacid

Nanosized hierarchical micro-mesoporous ZSM-5 material has been successful synthesized using the double templating approach performed by a two-step crystallization process. The synthesis route involved static hydrothermal aging and ultrasonic-assisted aging. It was established that ZSM-5 synthesized under appropriate ultrasound stimulation possessed larger cumulative pore volume and smaller crystal size than that of samples synthesized without ultrasound stimulation. A serious of micro-mesoporous ZSM-5 supported HPW catalysts with various acid loadings were prepared by the impregnation method. The catalytic performances were investigated in the alkylation of o-xylene with styrene. Alkylation results showed that HPW/micro-mesoporous ZSM-5 exhibited better activities than that of HPW/microporous ZSM-5 catalyst. HPW-20/micro-mesoporous ZSM-5 catalyst had the best catalytic performances in terms of yield and stability, which can be attributed to its maximum medium strong acid amount and its smaller particle size which is favorable for fast diffusion of products.