Oxidative dehydrogenation of propane with CO₂ - A green process for propylene and hydrogen (syngas)

The CO₂ oxidative dehydrogenation of propane (CO₂-ODHP) reaction provides a platform to utilize carbon dioxide, a greenhouse gas and commonly available propane, in the production of value-added chemicals. A thermodynamic study of the process was achieved by simulation in the Aspen Plus software, using the method of minimization of Gibbs free energy. Sensitivity analysis was performed while varying the feed CO₂/C₃H₈ molar ratio. At higher CO₂/C₃H₈ molar ratios, lower temperatures are required to achieve higher propane conversions. The selectivity towards propylene production increased with lower CO₂/C₃H₈ ratios and higher temperatures. It was found that a feed with CO₂/C₃H₈ molar ratio of 1.0 was the optimum to obtain a syngas ratio (H₂/CO) of unity without compromising propylene product, at 850 °C and 1 bar. At higher CO₂/C₃H₈ molar ratios, selectivity towards CO is enhanced, thus results in lower syngas ratios (H₂/CO), whereas for a specific feed CO₂/C₃H₈ molar ratio higher temperatures favor selectivity to H₂, resulting in relatively higher syngas ratios.