Synthesis of Hierarchical Micro-mesoporous ZSM-5 Zeolite and its Catalytic Activity in Benzylation of Mesitylene

Hierarchical micro-mesoporous ZSM-5 (MFI type) zeolite was synthesized by using corn plant stem pith powder from agricultural waste as hard template under simple hydrothermal method. The additional porosity generated using this pith powder into the zeolites precursor gel yielded hierarchical micro-mesoporous ZSM-5 zeolite (C-ZSM-5). Conventional micro porous ZSM-5 (ConvZSM-5) was also prepared by same procedure without adding the corn stem pith powder to compare the catalytic performances. The prepared C-ZSM-5 zeolite exhibited 89% conversion, much greater than ConvZSM-5 (33%). Selectivity in the formation of 2-Benzyl-1, 3, 5-trimethylbenzene, by benzylation with C-ZSM-5 (70%) is more than two times than ConvZSM-5 (32%). This benzylation can be used as a test reaction to evidence the formation of hierarchical micro-mesoporous nature of the material. C-ZSM-5 exhibited better selectivity and benzyl alcohol conversion due to the presence of hierarchical pores and strong acidy in C-ZSM-5.The product formed in the above reaction was separated and further confirmed by (HNMR)-H-1 and (CNMR)-C-13. Even after consecutive recycles every month for three months, the conversion and desired products selectivity had not been affected. The hierarchical pores present in the catalyst further improved the stability of the zeolites. Hence this catalyst could be very useful for industrially important reactions.

Automated summary

Hierarchical micro-mesoporous ZSM-5 zeolite was synthesized by using corn plant stem pith powder as a hard template. The addition of pith powder increased the porosity of the zeolites, resulting in better catalytic performance with higher conversion rate and selectivity in the formation of 2-Benzyl-1, 3, 5-trimethylbenzene. The presence of hierarchical pores and strong acidity in C-ZSM-5 contributed to its improved selectivity and stability.