Vanadium-doped porous silica materials with high catalytic activity and stability for propane dehydrogenation reaction

Abstract

Novel V-based catalysts, vanadium-doped porous silica materials (V-SiO2), have been successfully prepared by a facile one-pot synthetic method for propane dehydrogenation (PDH). The structure-activity relationships of V-SiO2 with different vanadium contents have been well elucidated through several state-of-the-art characterization techniques. The results indicate that vanadium species are highly dispersed in the channels of the porous silica materials, and that both monomeric and low-polymerized V species are the main active sites for PDH reaction. V-SiO2 catalysts with moderate vanadium doping display a mesoporous structure with high specific surface area and large pore volume, whereas excessively high vanadium doping will disrupt the mesoporous structure due to the formation of bulk V2O5 crystallites. Catalytic tests have shown that V(2)-SiO2 catalyst with a V/Si mass ratio of 1:12 exhibits optimal catalytic activity and stability for PDH reaction, achieving a superior propane conversion that decreases from 64% to 30% and stable propylene selectivity of ∼90% over 21 h at 580 °C. Its regeneration leads to an 8% decrease in propane conversion and about 94% propylene selectivity within 6 h after a second PDH cycle, demonstrating that this V(2)-SiO2 catalyst has excellent long-term catalytic stability. This work may expedite the development of vanadium-doped porous silica materials obtained by an one-pot method for use in catalysis.