CO2 Assisted Oxidative Dehydrogenation of Propane to Propylene over Fluidizable MoO3/La2O3-γAl2O3 Catalysts

This study investigated the catalytic performance of a novel fluidizable MoO3 supported on La2O3-gamma Al2O3 composite for oxidative dehydrogenation (ODH) of propane to propylene with and without CO2. The La2O3-gamma Al2O3 composites were synthesized by a coprecipitation method, while the active MoO3 was deposited by an incipient wetness impregnation approach. The incorporation of La2O3 controlled both the acidity and reducibility of the catalysts, as revealed by NH3-TPD and H-2-TPR analysis, respectively. The N-2 adsorption/desorption isotherms analysis indicated the mesoporous pore size distribution of the catalysts. The ODH of propane experiments were developed in a fluidized CREC Riser Simulator by feeding propane with or without CO2. The performance of the synthesized catalysts was found to be a function of the La2O3 content of the support. In general, the propane conversion declined slightly, while propylene selectivity increased with the increasing La2O3 content. It was hypothesized that the presence of basic La2O3 reduced the acidity and the non-selective sites of gamma-Al2O3, which were responsible for deep oxidation of propylene and propane. Among the studied catalysts, MoO3/La2O3-gamma-Al(2)O(3)1:2 displayed the highest propylene yield of 28.2 % at 600 degrees C in the absence of CO2. However, a superior yield of 35.2% was achieved over the same catalyst by the introduction of CO2-admixture in the feed at 550 degrees C.