Higher Hydrocarbons Synthesis from CO2 Hydrogenation Over K- and La-Promoted Fe–Cu/TiO2 Catalysts

Developing selective and active catalyst is critical for CO2 hydrogenation to higher hydrocarbons especially C5+ products. The present work reports on the significant promoting effects of K and La addition to Fe–Cu/TiO2 catalyst on higher hydrocarbon production from CO2 hydrogenation. The incorporation of both K and La promoters can improve both CO2 hydrogenation activity and selectivity to higher hydrocarbons of Fe-based catalyst. Characterization by temperature-programmed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) showed that the presence of K promoter significantly decreased the adsorption of H2, which suppressed the CH4 formation. On the other hand, La addition can promote the moderately adsorbed CO2 species (mainly monodentate carbonate species), which leads to the enhanced C5–C7 selectivity. The simultaneous use of promoters La and K can tailor the H and C coverage on the catalyst surface, which plays an important role in altering product distribution in CO2 hydrogenation.