Catalytic cracking of C5 raffinate to light olefins over phosphorous-modified microporous and mesoporous ZSM-5.

Phosphorous-modified microporous and mesoporous ZSM-5 catalysts (XP/C-ZSM5) were prepared with a variation of phosphorous content (X = 0.17, 0.3, 0.7, 1.4, and 2.7 wt%), and they were applied to the production of light olefins (ethylene and propylene) through catalytic cracking of C5 raffinate. The effect of phosphorous content on the physicochemical properties and catalytic activities of XP/C-ZSM5 catalysts was investigated. It was revealed that physicochemical properties of XP/C-ZSM5 catalysts were strongly influenced by phosphorous content. Strong acidity of XP/C-ZSM5 catalysts decreased with increasing phosphorous content. In the catalytic cracking of C5 raffinate, both conversion of C5 raffinate and yield for light olefins (ethylene and propylene) showed volcano-shaped curves with respect to strong acidity. This result indicates that strong acidity of XP/C-ZSM5 catalysts played an important role in determining the catalytic performance in the catalytic cracking of C5 raffinate. Among the catalysts tested, 0.3P/C-ZSM5 catalyst with moderate strong acidity showed the best catalytic performance.