Catalytic Hydrogenation of CO2 to Isoparaffins over Fe-Based Multifunctional Catalysts

Direct conversion of CO2 into isoparaffins, ideal clean hydrocarbon fuel components, would be an eco-friendly way of mitigating CO2 emissions and replacing fossil fuels. Herein, we realize a one-step high-yield synthesis of isoparaffins from CO2 hydrogenation, catalyzed by a multifunctional Na–Fe3O4/HMCM-22 catalyst. A selectivity of 82% among hydrocarbons was achieved for C4+ hydrocarbons, of which isoparaffins could account for 74%, while CO selectivity was as low as 17% at a CO2 conversion of 26%. The high yield to isoparaffins was derived owing to well matching of three tandem reactions comprising reverse water–gas shift, C–C coupling and isomerization. Unique pore structure and appropriate Brønsted acid properties of HMCM-22 effectively suppressed aromatization, while promoting isomerization. Coke deposition inside the micropores of HMCM-22 causes the decline of isoparaffin yield without changing the total yield of heavy hydrocarbons. Both the physicochemical properties and catalytic performances of the catalysts could still keep their original levels after several reaction-regeneration cycles, indicating a promising potential application in the future commercialization process of CO2 hydrogenation.