Development of Mg-Modified Fe-Based Catalysts for Low-Concentration CO₂ Hydrogenation to Olefins

Abstract

With mounting concerns about reducing carbon emissions, developing a catalyst that can be used in the hydrogenation of CO 2 to olefins makes sense. Considering the high cost of CO 2 capture, the direct use of low-concentration CO 2 to produce olefins is more promising. In this work, we develop a reliable Mg-modified Fe-based catalyst for the low-concentration hydrogenation of CO 2 to olefins. The optimized KFeMnMg 0.15 catalyst exhibits a high olefin yield of 15.4% with an olefin selectivity of 61.2% at a low CO 2 concentration of 10%. The structural characterizations reveal that the Mg promoter regulates the adsorption strength of reactants CO 2 and H 2 , and the intermediate is CO, which promotes the conversion of CO 2 and inhibits the hydrogenation of olefins. In addition, the Mg promoter plays a critical role in facilitating the formation of iron carbide, which is the active phase of the hydrogenation of CO 2 to olefins. Thus, multiple functions of the Mg promoter realize the efficient conversion of low-concentration CO 2 to olefins.

Recent Advances Hydrogenation of Carbon Dioxide to Light Olefins over Iron-Based Catalysts via the Fischer–Tropsch Synthesis

“…MgO and TiO 2 were also commonly used catalyst carriers for the preparation of low carbon olefins by CO 2 hydrogenation. The electron-donating property and surface alkalinity of MgO promoted the dissociation and adsorption of CO, limiting the hydrogenation ability of the Fe-based catalysts, while the stability of the basic sites effectively prevented the loss of the active substances and the basic sites during the reaction process, which improved the selectivity of light olefins. , XRD and CO 2 -TPD measurements showed that the (111) crystalline facets of MgO increased the surface alkalinity of the catalyst, facilitated the dissociative adsorption of CO, and accelerated the reaction rate. , The oxygen vacancies in the TiO 2 carrier help bridge the adsorption of carbonate species and promote the decomposition of carbonate species into carbon intermediates, accelerating the C–C coupling reaction …”