Modified Dendritic Mesoporous Silica Nanospheres Composites: Superior Pore Structure and Acidity for Enhanced Hydrodesulfurization Performance of Dibenzothiophene

Dendritic mesoporous silica nanospheres (DMSNs) with a center-radical pore structure were successfully fabricated with ZSM-5 seeds to synthesize hierarchically meso-microporous ZSM-5/DMSN (ZD) materials which were used as the support for preparing HDS catalysts. The catalytic activities were evaluated by adopting DBT as the model oil. ZD composites and the corresponding catalysts were well characterized by XRD, XPS, HRTEM, and other techniques. The characterization results manifested that the specific center-radical pore structure was retained after incorporation of microporous zeolite ZSM-5; thus, ZD exhibited a wide pore diameter of about 17 nm, which was definitely preferable for mass transfer in the S removal process. Meanwhile, the open pore channels enhanced the accessibility of the active sites on the internal surface of the catalysts. Introducing ZSM-5 seeds into the framework of DMSNs also improved the acidity and modulated the metal-support interaction as well. As a result, NiMo/ZD series catalysts demonstrated high HDS activities, of which NiMo/ZD-3 achieved the highest HDS efficiency of 98.3%. The superior catalytic performance not only originated from the large center-radical pore structure and good acidity of support but also related to the suitable metal-support interaction and perfect dispersion of the metallic active sites.