Preparation of HZSM-5 catalysts with different ratios of structure directing agents and their effects on the decomposition of exo-tetrahydrodicyclopentadiene under supercritical conditions and coke formation

Abstract

Zeolite catalysts (ZSM-5) were synthesized using different ratios of structure directing agents (SDA) and Si/Al, and the synthesized ZSM-5 samples were used in the endothermic decomposition reaction of exo-tetrahydrodicyclopentadiene (exo-THDCP). The ZSM-5 synthesized with a 6.0:100 SDA/SiO2 ratio and Si/Al ratio of 20 (S20/P6.0) showed higher mesoporosity than those of the other synthesized and commercial ZSM-5 catalysts. The decomposition reaction of exo-THDCP using the S20/P6.0 catalyst yielded the highest conversion of 58.4% after 65 min, whereas the commercial catalyst rapidly became deactivated and exhibited only 31.2% conversion, which was the same conversion obtained without the catalyst. The coke analysis results indicated that the ratio of mesopore to micropore volume of the catalyst was a major factor in determining the amount of internal and external coke produced in the catalyst. Moreover, the mesopore/micropore volume ratio affected the composition of soluble coke.