The catalytic CO2 hydrogenation to higher hydrocarbons has attracted increasing attention due to environmental and industrial concerns. Past efforts have focused on modifying Fe-based catalysts and promoters with or without support. The present work investigates the effect of bimetallic Fe-Cu catalyst for CO2 hydrogenation to C2+ hydrocarbons. Catalysts were prepared by a pore-filling incipient wetness impregnation on gamma-alumina (SA = 150 m2 g-1, D = 22 nm, PV = 1.0 mL g-1) followed by drying and calcination. Hydrocarbon synthesis activity was tested in a fixed-bed flow reactor at 573 K under 1.1 MPa using 24% CO2/72% H2/ 4% Ar as feed gas after H2 reduction at 673 K. For online analysis, gaseous products of Ar, CO, CH4 and CO2 were analyzed by micro GC-TCD and the gas-phase hydrocarbon products (C1 – C7) were analyzed with GC-FID. Our results show that when Fe is combined with a small amount of Cu, the CO2 conversion increases significantly. Addition of K as the promoter to Fe-Cu further enhances the CO2 conversion in Fe-Cu catalysts. C2-C7 hydrocarbon space-time yield (STY) also shows maximum at the Cu/(Fe+Cu) atomic ratio of 0.17. Considering that Cu does not have the ability to generate C2-C7 hydrocarbons from CO2/H2, the combination of Fe with a small amount of Cu leads to a significant bimetallic synergetic promotion of C2+ hydrocarbons synthesis in CO2 hydrogenation. As Cu amount increases, CH4 STY keeps decreasing as Cu content increases, indicating that Cu addition can suppress CH4 formation. On the other hand, higher K/Fe ratio significantly promote the C2-C4 olefin formation and increase the olefin/paraffin ratio, as well as chain growth probability. On the Fe-Cu(0.17)/K(1.0)/Al2O3 catalyst, C2-C4 olefins become dominant products in the light hydrocarbons, and CH4 is inhibited as K amount increases. Detailed analysis of bimetallic effect will be discussed in characterization results.

Bimetallic Fe-Cu catalysts for CO2 hydrogenation to C2+ hydrocarbons

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.