Sodium‐Containing Spinel Zinc Ferrite as a Catalyst Precursor for the Selective Synthesis of Liquid Hydrocarbon Fuels

Abstract

A microwave-assisted hydrothermal synthesis produces ZnFe₂ O₄ containing Na residue as a precursor to a CO₂ hydrogenation catalyst that displays high CO₂ conversion and high selectivity to liquid hydrocarbon products in the gasoline and diesel range with high olefin-to-paraffin ratios. Compared to reference catalysts derived from Fe₂ O₃ and a ZnO-Fe₂ O₃ physical mixture, the ZnFe₂ O₄ -derived catalyst contains well-dispersed iron particles with Zn serving as a structural promoter. A profound effect of the residual Na as an electronic promoter is also observed, which improves the selectivity for C₅₊ hydrocarbons and olefins. The ZnFe₂ O₄ -derived catalyst exhibits excellent performance in the CO₂ Fischer-Tropsch reaction as it forms the active Hägg iron carbide (χ-Fe₅ C₂ ) phase readily through the in situ carburization of iron.