Microemulsion based synthesis of promoted Fe–Co/MgO nanocatalyst: Influence of calcination atmosphere on the physicochemical properties, activity and light olefins selectivity for hydrogenation of carbon monoxide

Abstract

Nanostructured promoted Fe–Co/MgO catalysts were fabricated by microemulsion technique and used for Fischer-Tropsch synthesis, for the first time. Regarding the deficiency of the systematic investigation correlated to the calcination atmosphere on FT catalytic performance, in this study, the effect of different calcination atmospheres on the catalytic activity, product selectivity, and physicochemical properties of promoted Fe–Co/MgO catalyst was investigated. To obtain uniform particle size distribution, the microemulsion technique was used. The prepared nanocatalysts were characterized by XRD, TGA, BET, ICP-OES, FESEM, TEM, FTIR, XPS, and H2-TPR. The higher activity, methane selectivity, and lower C3+ selectivity were obtained for the air-calcined catalyst. Calcination under Ar atmosphere resulted in lower activity, methane selectivity, but higher C3+ selectivity (with high paraffin contents). Characterizations indicated that these performances are related to the metal particle size and reducibility. The air-calcined catalyst with smaller particle size and higher reducibility rather than Ar-calcined one, demonstrated higher activity, oxidized more quickly in the preliminary operation period of Fischer-Tropsch synthesis, and encouraged the formation of CH4 and CO2.