ZSM-5 MICROSTRUCTURE AND ITS PERFORMANCE FOR CATALYTIC CRACKING HEXANE AND NAPHTHA

摘要

Catalytic cracking naphtha to olefins, instead of the traditional steam cracking process, has gained much attention, due to the catalytic process producing high yield of light olefins, especially propylene and reducing energy cost and CO2 emission[l]. Many efforts are devoted to the development of high effective catalysts which are the most important factors influencing catalytic cracking process. Zeolites synthesized by different templates exhibited different acid properties and acid distribution[2]. Herein, three kinds of ZSM-5 zeolites with similar crystal size and Si/Al ratio were synthesized using n-butylamine (NBA), tetrapropylammonium (TPA~+) and no template (NT) respectively. Applied to n-hexane cracking, ZSM-5 synthesized by NBA and TPA~+ showed a little higher initial ethylene and propylene (P+E) yields than ZSM-5 by NT. However, the lifetime of the latter was much longer than the former two (fig.l(A)). The results are attributed to the acidity properties of the ZSM-5 materials.