Abstract
High-temperature treatment is key to the preparation of zeolite catalysts.Herein,the effects of high-temperature treatment on the property and performance of HZSM-5 zeolites were studied in this work.X-Ray diffraction,N2 physisorption,27Al magic angle spinning nuclear magnetic resonance(MAS NMR),and temperature-programmed desorption of ammonia results indicated that the high-temperature treatment at 650 ℃ hardly affected the inherent crystal and texture of HZSM-5 zeolites but facilitated the conversion of framework Al to extra-framework Al,reducing the acid site and enhancing the acid strength.Moreover,the high-temperature treatment improved the performance of HZSM-5 zeolites in n-heptane catalytic cracking,promoting the conversion and light olefins yield while inhibiting coke formation.Based on the kinetic and mechanism analysis,the improvement of HZSM-5 performance caused by high-temperature treatment has been attributed to the formation of extra-framework Al,which enhanced the acid strength,facilitated the bimolecular reaction,and pro-moted the entropy change to overcome a higher energy barrier in n-heptane catalytic cracking.
基金项目
National Natural Science Foundation of China(21908010)
Jilin Provincial Department of Science and Technology(20220101089JC)
Education Department of Jilin Province(JJKH20220694KJ)
NETL
NSTL
维普
万方数据