Selective Hydrogenation of CO₂ to Hydrocarbons: Effects of Fe₃O₄ Particle Size on Reduction, Carburization, and Catalytic Performance

Abstract

Conversion of CO2 via hydrogenation to chemicals and fuels is deemed to be a promising route to utilize carbon sources. Iron-based catalysts are widely used in CO2 hydrogenation to produce value-added hydrocarbons. The prereduction and reaction conditions usually cause complicated evolution of iron phases. In this work, Fe3O4 nanoparticles with different particle sizes were synthesized to investigate the effects of the reduction and carburization behavior on the catalytic performance of iron-based catalysts during CO2 hydrogenation. It was demonstrated that larger Fe3O4 nanoparticles are more difficult to be reduced and carburized. Various iron species were formed in catalysts during the reaction, resulting in different catalytic performances. The high content of inactive α-Fe caused lower CO2 conversion and olefins-to-paraffins ratio (O/P) over larger Fe3O4 nanoparticles. The highest CO2 conversion (41.7%) and O/P (1.71) were obtained over the catalyst with the appropriate proportion of Fe3O4 and Fe5C2 phases.