Selective Hydrogenation of CO 2 to Hydrocarbons: Effects of Fe 3 O 4 Particle Size on Reduction, Carburization, and Catalytic Performance

Conversion of CO 2 via hydrogenation to chemicals and fuels is deemed to be a promising route to utilize carbon sources. Iron-based catalysts are widely used in CO 2 hydrogenation to produce value-added hydrocarbons. The prereduction and reaction conditions usually cause complicated evolution of iron phases. In this work, Fe 3 O 4 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 CO 2 hydrogenation. It was demonstrated that larger Fe 3 O 4 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 CO 2 conversion and olefins-to-paraffins ratio (O/P) over larger Fe 3 O 4 nanoparticles. The highest CO 2 conversion (41.7%) and O/P (1.71) were obtained over the catalyst with the appropriate proportion of Fe 3 O 4 and Fe 5 C 2 phases.