Vanadium Pentoxide Catalyst over Carbon-Based Nanomaterials for the Oxidative Dehydrogenation of Propane

Abstract

A series of V2O5 catalysts supported on multiwall carbon nanotube (MWCNT), single wall carbon nanotube (SWCNT), and graphene were synthesized by hydrothermal and reflux methods for oxidative dehydrogenation of propane (ODHP) to propylene. The catalysts were characterized by techniques including the BET surface area measurements, XRD, FTIR, H2-TPR, NH3-TPD, FESEM, and UV–vis diffuse reflectance spectroscopy. The performance of the catalysts and the supports were subsequently examined in a fixed bed reactor. The main products were propylene, ethylene and COx. The vanadium catalyst supported on graphene with C/V molar ratio of 1:1 synthesized through the hydrothermal method had the best performance under the reactor test conditions of 450 °C, feed C3H8/air molar ratio of 0.6, and the total feed flow rate of 90 mL/min resulting in average values of 53.6% and 50.7% for propylene selectivity and propane conversion, respectively. This catalyst was further employed in a series of experiments to study the effects of operating parameters including the reaction temperature, propane to air ratio, and the total feed flow rate on conversions and product selectivities using an experimental design method utilizing the response surface methodology (RSM) with central composite design at three levels. The resulting quadratic equations properly correlated the obtained experimental data. Optimum conditions for maximizing propane conversion and propylene selectivity as well as minimizing the COx selectivity were determined at the temperature of 500 °C, C3H8/air molar ratio of 0.28, and total flow rate of 60 mL/min. Ultimately, results under optimum conditions revealed satisfactory agreement between the experimental and predicted data.