Molybdenum-based catalysts supported on alumina for direct dehydrogenation of isobutane

Abstract

A series of Al 2 O 3 supported Mo-based Mo/Al-X ( X = 1, 2, 3, 4) catalysts were prepared by incipient-wetness impregnation method. The Mo/Al-X catalysts were evaluated in the isobutane direct dehydrogenation reaction at 600 °C, and the physicochemical properties of Mo/Al-X catalysts were investigated by using XRD, BET, SEM, H 2 -TPR, NH 3 -TPD, TEM, XPS and TG-DTG techniques. The results indicated that the MoO x species were highly dispersed, and Mo 4+ ions were the main active species for the reaction of isobutane direct dehydrogenation to isobutene. The Mo/Al-1 catalyst displayed the hollow microspheric structure with mesoporous shell and big pore window. And Mo/Al-1 catalyst with the lowest S BET value of 167 m 2 •g −1 exhibited optimal catalytic performance, achieving superior and stable isobutane conversion of 30.5% and isobutene selectivity of 84.6%, respectively. Excellent catalytic performance, anti-sintering and carbon-resistance ability of Mo/Al-1 catalyst are attributed to the low specific surface area, small particle size, high Mo 4+ /Mo 6+ molar ratio, strong Mo species and support interaction, and high concentration and strength of weak and medium-strong acid sites.