Vanadium-containing dendritic mesoporous silica nanoparticles: Multifunctional catalysts for the oxidative and non-oxidative dehydrogenation of propane to propylene

摘要

Vanadium-containing dendritic mesoporous silica nanoparticles (V-DMSNs) were successfully synthesized by the co-assembly and anion-assisted method. The V-DMSNs were applied as catalysts for the oxidative dehydrogenation of propane and non-oxidative dehydrogenation of propane reactions. DMSNs support exhibits good hydrothermal stability according to the effect of ageing temperature and time on the structure. V-DMSNs with different vanadium contents preserve original structural characteristics of DMSNs support with three-dimensional and center-radial pore structure. The direct co-assembly process contributes to enhancing the interaction between the VO4 species and DMSNs support. A high concentration of highly dispersed and isolated VO4 species can be achieved on the present V-DMSNs systems. The V-DMSNs catalysts show better catalytic performance in the oxidative dehydrogenation of propane compared with corresponding V/DMSNs catalysts prepared by impregnation method. V-DMSNs catalysts also show the direct dehydrogenation ability and high stability. The appropriate concentrations of isolated and neighboring VOx species are favorably involved in propane activation and propylene formation. To further investigate the structural characteristics of catalysts dynamically responding to reactive conditions, the structures of active sites and deposited carbonaceous species were analyzed by in-situ Raman spectroscopy. This work gives a novel multifunctional catalyst that shows superior catalytic performance in the oxidative and non-oxidative dehydrogenation of propane reactions.