(643f) Molten Salt Facilitated Oxidative Dehydrogenation of Ethane with in-Situ CO2 Capture and Utilization

Utilizing CO₂ for chemical production can be an economically attractive option for carbon emission reduction. Among the various CO₂ utilization approaches, oxidative dehydrogenation (ODH) with CO₂ as a soft oxidant offers the potential to produce value-added CO while upgrading light alkanes, such as ethane to ethylene. However, CO₂-assisted ethane ODH is nevertheless an energy intensive process largely due to the limited ethane and CO₂ conversions and hence a high energy cost for product separations. Currently, the highest reported CO₂ conversion in CO₂-ODH of ethane is only 50% at 800 °C. Meanwhile, ethylene yield is generally limited to <20% at lower temperature. Aside from these challenges, CO₂-ODH requires a concentrated CO₂ stream. This adds another energy-consuming step since CO₂ capture from emission sources such as fossil-based power plants are highly energy intensive. To address the challenges from both CO₂ separation and CO₂-ODH, we propose to utilize tailored molten salts as a reaction medium for simultaneous CO₂ capture and utilization. In this scheme, we demonstrate that CO₂ can be captured from a (simulated) power plant flue gas and subsequently utilized via a modified reverse water gas shift reaction with a high CO₂ conversion. Results from temperature programmed reaction (TPR) and in-situ Diffuse Reflectance Infrared Spectroscopy (DRIFTS) suggest that the coupled radical reactions and reverse water gas shift reaction in the molten salt medium was responsible for the high CO₂ to CO conversion and ethylene yield.