VMOF derived VOx/Al2O3 millimeter spherical catalyst for propane dehydrogenation with enhanced activity and stability

Abstract

VMOF derived VO_x/Al₂O₃ millimeter spherical catalysts were prepared using MIL-100(V) as precursor by gum arabic-assisted sol-gel and N₂-air dual calcination method, and the effects of preparation method and V loading of catalyst on the properties of VO_x/Al₂O₃ and propane dehydrogenation performance were investigated systematically. The as-prepared spherical catalyst exhibited a watermelon-seed-like structure with VMOF derived VO_x as seeds, and isolated VO_x species with good dispersion could be achieved even at a higher vanadium loading owing to the isolation effects of organic ligands of MOF and alumina support. The hierarchical porous structure with mesopores of alumina and micro-scale rod-like pores left by the decomposition of MIL-100(V) through N₂-air dual calcination could be created. Besides, weaker interaction between VO_x derived from MOF and alumina is beneficial for increasing the amount of reducible isolated species and decreasing strong acid site amount. 7.4VO_x/Al₂O₃ presented the highest catalytic performance with propane conversion of 30.8 %/28.2 % (initial/final) and propylene selectivity of 91.6 %/94.7 % (initial/final) within 5.25 h reaction due to the good dispersion of VO_x species, hierarchical porous structure and moderate amount of surface acid sites. The high stability and excellent reaction-regeneration cycle performance of 7.4VO_x/Al₂O₃ offered a great potential for the industrial application of vanadium-based catalysts in the propane dehydrogenation reaction.