Synthesis of highly ordered TiO2-Al2O3 and catalytic performance of its supported NiMo for HDS of 4, 6-dimethyldibenzothiophene

Abstract

The highly ordered mesoporous TiO2-Al2O3 composite oxides were prepared via a facile evaporation-induced self-assembly (EISA) method. All of those synthesized materials were characterized by means of XRD, XRF, N2 adsorption, FTIR, Py-FTIR and TEM. The results show that the hexagonally ordered mesoporous TiO2-Al2O3 oxides with high specific surface area, high thermal stability and narrow pore size distributions were successfully synthesized by EISA. The corresponding NiMo catalysts supported on TiO2-Al2O3 oxides were further characterized by H2-TPR, HRTEM and XPS. Their hydrodesulfurization catalytic performances were tested in a fixed-bed reactor, using 4,6-dimethyldibenzothiophene as the probe. The analyzing results exhibit that the incorporation of TiO2 could effective weaken the support-metal interactions, thus enhancing the reduction degree of active metals and forming more “Type II” Ni-Mo-S active phases that would be beneficial for the HDS of highly refractory organosulfur compound. The catalytic results reveal that the 4,6-DMDBT conversion over NiMo/TA-n catalysts gradually increased as the Ti/Al molar ratio increases, and reaches a maximum values at NiMo/TA-0.4. The NiMo/TA-0.4 exhibited the highest hydrodesulfurization catalytic performance of 4,6-DMDBT due to the synergistic effect of suitable textural properties, high thermal stability and moderate metal-support interactions.