Progress on heterogeneous catalysis for reductive functionalization of CO₂ with amines/aromatics and H₂

The reductive functionalization of CO₂ couples CO₂ reduction with C—X bond formation, incorporating CO₂ into organic molecules as formyl, methylene, hydroxymethyl, or methyl groups, thereby significantly expanding the product scope of CO₂ conversion. Particularly, the heterogeneous catalyzed reductive functionalization of CO₂ with amines/aromatics using H₂ as reductant shows great potential for industrial-scale production of valuable chemicals such as formamides, methylamines, and methylated aromatics, which makes it a research hotspot. In the reductive functionalization of CO₂ with amines, supported metal nanomaterials （e.g., Pd, Au, Pt, Ru, Re, Ir, Cu, and Co） are widely used. Strategies such as support selection and surface modification, decoration of metal nanoparticles with organic ligands or metal oxides, and alloy formation have been utilized to tune the electronic structure of active metal centers and introduce multiple active sites on the support. These strategies can promote H₂ activation at the metal centers and enhance the adsorption and activation of CO₂, amine substrates, and the corresponding intermediates on the catalyst. Consequently, the catalytic activity, cyclic stability and the selectivity to N-formylation or N-methylation product can be improved. In the methylation reactions of aromatics with CO₂ and H₂, dual-functional catalysts composed of mixed metal oxides （or Re/TiO₂） and zeolites are employed. In the reaction, the mixed metal oxides （or Re/TiO₂） reduce CO₂ to methanol while the acidic sites of the zeolite activate methanol and aromatics to promote C—C coupling and thus produce methylated products. By tailoring the composition of the mixed metal mixed oxide and the acidic sites （type, density, and distribution） of the zeolite, as well as optimizing the mixing ratio and mode of these two components, the efficiency of CO₂ hydrogenation and aromatics methylation can be significantly improved and the methanol generation, migration, and consumption rates are balanced, thereby enhancing both feedstock conversion and target product selectivity. By far, the CO₂ and aromatics conversion rates can exceed 30% with product selectivity surpassing 90%. Currently, systematic research achievements have been obtained for CO₂ reductive functionalization in the heterogeneous catalyst design and product regulation, laying a solid foundation for subsequent technological innovation and applications.