Catalytic Cracking and Aromatization of C4-C5 Hydrocarbons over Zsm-5 Zeolite: Activity and Regeneration

Prancharee Teerathanakit1, Siriporn Jongpatiwut1, Boonyarach Kitiyanan1, and Nakarin Mongkolsiri2. (1) The Petroleum and Petrochemical College, Chulalongkorn University, Soi Chula 12, Phyathai Rd., Patumwan, Bangkok, 10330, Thailand, (2) Rayong Olefin Company Limited, 271 Sukhumvit Rd., Map Ta Phut, Muang, Rayong, Thailand

Much attention has recently been focused on the ZSM-5 catalyzed-transformation of light hydrocarbons to convert cheap raw materials into more valuable compounds. In this work, cracking and aromatization of C4-C5 hydrocarbons were studied on the ZSM-5 zeolites with different Si/Al ratios. The activity of the catalytic cracking was investigated with individual compounds, i.e., n-butane, 1-butene, i-butene, n-pentane, and mixed C4 feedstocks in order to analyze the coke precursors. The experimental results showed a conversion decrease in the order of 1-butene > i-butene > mixed C4 and n-butane ~ n-pentane. The characterization of the spent catalyst with the TPO technique showed that a large quantity of coke was observed on the catalysts used with C4 olefin species due to the highly reactive olefins oligomerization. The regeneration temperature at 500oC could remove the major fraction of coke formation and the relationship between time on stream (TOS) and amount of coke was linear.