Research on propene oligomerization reaction over the Fenton's reagent modified ZSM-5

ZSM-5 zeolite was modified by Fenton's reagent, FeSO₄ and H₂O₂ aqueous solutions using impregnation method, respectively. All these catalysts were characterized by XRD, ICP-OES, N₂ adsorption-desorption, NH₃-TPD, Py-FTIR and evaluated in propene oligomerization process. The results demonstrated that the framework of the parent ZSM-5 was well preserved after modification with Fenton's reagent, FeSO₄ or H₂O₂ solutions. However, the SiO₂/Al₂O₃ ratios for all the modified ZSM-5 samples increased due to the dealumination. Furthermore, Fe was detected in Fenton-ZSM-5 while no Fe was observed for FeSO₄-ZSM-5 catalyst. The BET surface areas and total pore volumes of three modified catalysts significantly increased compared with the original ZSM-5 sample. Among them, the BET surface area of the Fenton-ZSM-5 increased by 17.86%.The increase of mesopores was probably caused by the removal of the residual organic template in the catalysts due to the generation of·OH radicals by Fenton's reagent and H₂O₂. The Fenton-ZSM-5 catalyst formed new acid sites of Brønsted (B) and Lewis (L) with little change in the total calculated amount, which significantly changed the B/L ratio. Compared with the parent ZSM-5, the Fenton-ZSM-5 catalyst exhibited the best activity and stability for propene oligomerization reaction. The initial propene conversion and diesel selectivity were as high as 98.3% and 92.4%, respectively, and kept at >80% and >82% for about 24 h, respectively.