Syngas Production through Chemical-Looping-Enhanced Hydrogenation of Carbonates

Direct hydrogenation of carbonates (DHC) technology represents a breakthrough alternative to conventional syngas production processes that rely on fossil fuels. Nevertheless, it is constrained by a low carbonate conversion efficiency and suboptimal hydrogen utilization. Here, a novel strategy of chemical-looping-enhanced hydrogenation of carbonates (HC-CL) is proposed for the coproduction of metal oxides and syngas, which divides the DHC process into two half-looping processes involving H2-reduction and decarbonation-oxidation. An excellent redox catalyst of spinel Ce5/MgFe2O4 is developed to drive the HC-CL, which can transform into the rock salt structure of Ce5/MgxFeyO–Fe0 to provide abundant Fe metal sites and oxygen vacancies (Ov) after H2-reduction, and regenerate itself through efficiently splitting CO2 from carbonates into CO during the decarbonation-oxidation. Reduction-regeneration mechanism of Fe species ensures the redox reversibility of Ce5/MgFe2O4, achieving a high CO2-splitting efficiency of 70% over 10 HC-CL cycles. The techno-economic analysis based on the process simulation further illustrates that the HC-CL process can save 2 GJ/tcarbonate of energy consumption, 0.5 tCO2/tcarbonate of CO2 emissions, and 55 $/tcarbonate of costs than the DHC process coupled with H2 separation and recycling utilization. Therefore, the HC-CL process turns out to be a promising novel technology for syngas production.