Oxidative Dehydrogenation of Ethane: A Chemical Looping Approach

The current study investigates a chemical‐looping‐based oxidative dehydrogenation (CL‐ODH) concept for ethane‐to‐ethylene conversion. In this cyclic redox scheme, an oxide‐based redox catalyst is used to selectively combust hydrogen from ethane dehydrogenation. As the hydrogen product limits ethane conversion, in situ oxidation of hydrogen enhances the ethane conversion and ethylene yield. Moreover, heat required in ODH is compensated by re‐oxidation of the oxygen‐deprived redox catalyst, enabling auto‐thermal operation for the overall process. Compared to steam cracking, CL‐ODH can potentially achieve higher efficiency with lower CO2 and NOx emissions. Silica and magnesia‐supported manganese oxides are investigated. It is determined that unpromoted Mn/SiO2 and Mn/MgO redox catalysts exhibit low selectivity towards ethylene. The addition of promoters such as sodium and tungsten renders effective redox catalysts with satisfactory activity, selectivity, oxygen carrying capacity, and redox stability. Oxidative dehydrogenation: A chemical‐looping‐based oxidative dehydrogenation (CL‐ODH) process concept is introduced and validated at a lab scale. Under such a cyclic redox scheme, a metal‐oxide‐based oxygen carrier is used to selectively combust hydrogen from ethane dehydrogenation, thereby improving the equilibrium conversion and supplying heat for the reaction. This scheme can potentially realize high efficiency with low CO2 and NOx emissions.