Relationship between Surface Chemistry and Catalytic Performance of Mesoporous γ-Al₂O₃ Supported VO<i>_X</i> Catalyst in Catalytic Dehydrogenation of Propane

Abstract

Mesoporous γ-Al₂O₃ was synthesized via a cation-anion double hydrolysis approach (CADH). The synthesized mesoporous alumina displayed a relatively high surface area, a large pore volume and a narrow pore size distribution. By applying the mesoporous alumina as a support, supported vanadium catalysts were prepared and evaluated in the dehydrogenation of propane, exhibiting a superior catalytic performance over that supported on a commercial alumina. Materials were characterized with a variety of techniques such as X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet-visible spectroscopy, ⁵¹V magnetic angle spinning nuclear magnetic resonance, Raman spectroscopy, Fourier transformed infrared spectroscopy of pyridine adsorption and thermogravimetric-differential thermal analysis. The correlated structure-performance relationship of catalysts reveals that a higher crystallization temperature endows mesoporous alumina materials with more surface acid sites, favoring the formation of polymerized VO_X species, which are more active than isolated ones in the propane dehydrogenation, resulting in a better catalytic performance. The established relationship between surface chemistry and catalytic performance of supported VO_X catalysts suggests that a superior vanadium catalyst for propane dehydrogenation could be achieved by rationally enriching the concentration of polymeric VO_X species on the catalyst, which can be realized by tuning the surface acidity of alumina support.