Mn doping of Co-Al spinel as Fischer-Tropsch catalyst support

Abstract Mn-doped spinel oxides CoAl2O4 marked as CMA-m (m = Co/Mn atom ratio) herein were synthesized and evaluated for the first time as supports of Co-based Fischer-Tropsch synthesis (FTS) catalysts. HAADF-STEM images showed that Mn doping caused more crystal defects on the surface of CMA-m grains, which may provide more attachment sites for cobalt loading, leading to much smaller Co0 particle size of 15Co/CMA-m than that of 15Co/CoAl2O4. Data of H2/CO chemisorption showed that the interaction of highly dispersed Co0 with lattice Mn-doped CMA-m grain has a promotive effect on CO adsorption capability. FTS evaluation results demonstrate that 15Co/CMA-20 showed the highest CO conversion, C5+ selectivity and C5+ STY, benefiting from its high Co0 dispersion and CO chemisorption capability as a result of suitable Mn doping into the lattice of CoAl2O4, which was confirmed very different from the influence of impregnated Mn oxide over CoAl2O4.