Effect Of Silylation Of MCM-41 On Its Supported Pd Catalysts For Hydrodesulfurization

Environment legislations demand lower-sulfur transportation fuels all over the world. The development of novel catalyst with high efficiency to produce ultra-low sulfur diesel fuels is a meaningful topic.The Si-MCM-41 is a promising support for deep HDS catalysts, in this dissertation, silylation modification of MCM-41 was prepared using trimethylchlorosilane. XRD, N2 adsorption, CO adsorbed FTIR were performed to characterize the structure of the support. The hydrodesulfurization (HDS) performances of the supported Pd catalysts were studied using a model fuel containing 0.8 wt% DBT in decalin. ICP, H2-chemisorption, CO adsorbed FT-IR, XPS were performed to characterize the structure of the catalysts. The effects of support on the HDS performances of noble metal catalysts were discussed.Silylation modification of MCM-41 was prepared using trimethylchlorosilane, FTIR indicated that silylation process was successful. XRD and N2 adsorption indicated that the original structure of MCM-41 maintained after silylation, but the total pore volume, the pore size and the BET surface area decreased to some extent.The hydrodesulfurization (HDS) performances of the supported Pd catalysts were studied using a model fuel containing 0.8 wt% DBT in decalin. By comparing the activities and thioresistance in the HDS, the HDS activity and thioresistance were both improved by silylation modification. The long-term stability test of the supported Pd catalysts in DBT HDS indicated that the supported noble metal catalysts exhibited better thioresistance by silylation modification. By comparing the selectivities of the route and the products in the HDS, the catalysts activity was improved by silylation modification, especially the hydrogenation ability.The HYD activity was improved signally. Meanwhile, the catalysts exhibited low cracking activity by silylation modification.CO-IR indicated that the electronic properties of the Pd catalysts supported on silylated MCM-41 changed. The IR showed the frequency shifts (blue shift). The shift revealed the strong interaction between Pd and the silylated MCM-41. The XPS also proved the generation of Pdδ+. The CO-IR and XPS both indicated the improvement in activities and thioresistance originates from electron-deficient Pd.