Promotional Effects on the Catalytic Activity of Co-Fe Alloy Supported on Graphitic Carbon for CO2 Hydrogenation

Abstract

Starting from the reported activity of Co-Fe nanoparticles wrapped onto graphitic carbon (Co-Fe@C) as CO2 hydrogenation catalysts, the present article studies the influence of a series of metallic (Pd, Ce, Ca, Ca, and Ce) and non-metallic (S in various percentages and S and alkali metals) elements as Co-Fe@C promoters. Pd at 0.5 wt % somewhat enhances CO2 conversion and CH4 selectivity, probably due to H2 activation and spillover on Co-Fe. At similar concentrations, Ce does not influence CO2 conversion but does diminish CO selectivity. A 25 wt % Fe excess increases the Fe-Co particle size and has a detrimental effect due to this large particle size. The presence of 25 wt % of Ca increases the CO2 conversion and CH4 selectivity remarkably, the effect being attributable to the CO2 adsorption capacity and basicity of Ca. Sulfur at a concentration of 2.1% or higher acts as a strong poison, decreasing CO2 conversion and shifting selectivity to CO. The combination of S and alkali metals as promoters maintain the CO selectivity of S but notably increase the CO2 conversion. Overall, this study shows how promoters and poisons can alter the catalytic activity of Co/Fe@C catalysts, changing from CH4 to CO. It is expected that further modulation of the activity of Co/Fe@C catalysts can serve to drive the activity and selectivity of these materials to any CO2 hydrogenation products that are wanted.

The Effect of Mn, Al Doping on the CO2 Hydrogenation Performance of CaCO3‐Supported Fe‐Based Catalysts

“…Compared with unloaded cata-lysts, loaded catalysts facilitate the dispersion of the active phase and effectively prevent agglomeration and sintering of the active phase. [25] The carriers used for the loaded Fe-based catalysts are generally Al 2 O 3 , [26,27] C materials, [28,29] TiO 2 , [30,31] Zeolites, [32,33] etc. In contrast, the application of alkaline earth metals as carriers for CO 2 hydrogenation is rare.…”