Catalytic cracking of butene over nano-sized H-ZSM-5 catalyst

In a small continuous flowing fixed-bed reactor, the nano-sized H-ZSM-5 catalyst with crystal size of 20-50 nm vas applied to the catalytic cracking of butene front liquefied petroleum gas for propene synthesis. The catalytic performance of the nano-sized H-ZSM-5 catalyst was compared with that of two micro-sized H-ZSM-5 samples with crystal size of 1-2 and 1-6 mu m, respectively. Under the same reaction conditions, the nano-sized H-ZSM-5 and the micro-sized H-ZSM-5 samples had approximately the same initial butene conversion and propene yield. However, the nano-sized H-ZSM-5 sample exhibited better resistance to coking and deactivation. Under the reaction conditions of WHSV = 7 h(-1) p = 0.1 MPa, and theta = 560 degrees C, the butene conversion and propene yield over the micro-sized H-ZSM-5 samples decreased by about 50% after reaction for only 28 h, whereas over the nano-sized H-ZSM-5 sample the reaction time could be prolonged to 120 h. According to the coke analysis results,, the coking rate on the nano-sized H-ZSM-5 sample was lower than that on the micro-sized samples.