Promotional effects of CO₂ on the oxidative dehydrogenation of propane over mesoporous VO_X/γAl₂O₃ catalysts

CO₂ assisted oxidative dehydrogenation (ODH) propane to propylene over fluidizable mesoporous VO_x/La₂O₃-γAl₂O₃ catalysts has been investigated. The mixed oxide of La₂O₃ and γAl₂O₃ were synthesized by the co-precipitation technique and VO_x was deposited on the supports by an incipient wetness impregnation approach. The prepared catalysts were characterized by various physicochemical characterizations to establish the desired properties of the catalysts. The H₂-TPR indicated the supported VO_x reduced in a single stage, indicating the formation of a homogeneous specie. Both the acidity and surface area of the catalysts decreased with increase of La content, as confirmed by the NH₃-TPD and BET analysis, respectively. The CO₂ assisted ODH of propane experiments were developed in a fluidized CREC Riser Simulator at 520–600 °C. The introduction of CO₂ significantly enhanced both the propane conversion and propylene selectivity. Among the studied catalysts, VO_x/γ-Al₂O₃ catalyst showed highest propylene yields (42.7%) at 550 °C.