Enhancing the Ethylene Yield over Hybrid Adsorbent Catalyst Materials in CO2-Assisted Oxidative Dehydrogenation of Ethane by Tuning Catalyst Support Properties

CO2 emissions remediation has become of paramount importance due to the climate change issue. Combined CO2 capture and utilization has been considered as one of the promising technological solutions not only for mitigating CO2 emissions but also for producing valuable commodities such as chemicals and fuels. Herein, we report on the development of materials for combined capture and utilization of CO2 in the oxidative dehydrogenation of ethane to ethylene. The materials consisted of K-Ca double salt, to impart adsorption functionality, and Cr-incorporated SiO2 and H-ZSM-S, to impart catalyst functionality. The combined capture-reaction tests were performed under semi-isothermal conditions with adsorption at 600 degrees C and reaction at 700 degrees C. The results revealed that (K-Ca)(50)/(Cr-10@H-ZSM-5)(50) material with 10 wt % Cr and zeolite's SiO2/Al2O3 ratio of 280 exhibited the highest C2H6 conversion of 45.2% and C2H4 selectivity and yield of 78.3 and 35.4%, respectively. The better catalytic activity of this material relative to SiO2-based material was attributed to its higher Cr6+/Cr3+ ratio, as determined by XPS analysis. Moreover, the stability analysis of the materials after four adsorption-reaction cycles revealed a better stability for (K-Ca)(50)/(Cr-10@H-ZSM-5)(50) than for (K-Ca)(50)/(Cr-10%@SiO2)(50) which retained 72% of its initial CO2 adsorption capacity, 65% of its initial C2H6 conversion, and 76% of its initial C2H4 yield.