Chinese Journal of Chemical Engineering, Vol.23, No.7, 1131-1137, 2015
Catalytic cracking of 1-butene to propylene by Ag modified HZSM-5
Silver modified HZSM-5 (AgHZ) zeolite catalysts were prepared by ion exchange method and their catalytic properties in the 1-butene cracking reaction were measured. The catalysts were characterized by infrared spectroscopy with pyridine adsorption (Py-IR), N-2 adsorption and X-ray diffraction (XRD). The effects of Ag loading and steaming treatment on catalytic performances were studied. It is found that the activity of HZSM-5 (HZ) catalyst significantly decreases with the steaming time, whereas AgHZ catalysts show stable activity in the steaming time of 24-48 h and their activities increase with the Ag loading. When the steaming time is 24-48 h, the yield of propylene over HZ catalyst significantly decreases, whereas it is stable over AgHZ catalysts. The AgHZ catalysts with Ag loadings of 0.28%-0.43% (by mass) show similar propylene yields (similar to 30%), which are higher than that over the AgHZ catalyst with a Ag loading of 0.55% (by mass). These results indicate that the steam-treated AgHZ catalysts with optimum Ag loadings have higher yield of propylene and are more stable than the steam-treated HZ catalyst. The regeneration stability measurement in butene cracking also shows that the AgHZ catalyst steam-treated under a suitable condition has better stability than the HZ catalyst. (C) 2015 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.