Catalytic Cracking for Propylene Production over Au Catalyst Supported by External Surface-Modified ZSM-5 Zeolite

To improve the yield of propylene in fluidized catalytic cracking, a series of different Au/ZSM-5-TOS catalysts were prepared by modifying ZSM-5, using an external surface modification method and Au nanoparticles. The modified catalyst maintained the MFI structure of ZSM-5, whereas the pore-opening size of the zeolite relatively decreased, without affecting its internal structure. The acidity of ZSM-5, especially the Brønsted acidity, reduced. Among the studied catalysts, the 0.2 wt% Au/ZSM-5-1%TOS catalyst exhibited the best feedstock conversion and propylene selectivity, along with a significant increase in propylene selectivity and a slight decrease in the conversion of light diesel oil, even after water vapor treatment at 800 °C for 4 h. Its catalytic activity at 360 °C exceeded that of ZSM-5 at 460 °C, showing great application potential in petrochemical processes.