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

Liu, J. - Presenter, North Carolina State University
Gao, Y., North Carolina State University
Li, F., North Carolina State University
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.