Abstract
This work describes the preparation of mesoporous xMnFe oxide (x = 0, 0.05, 0.1, 0.2, 0.3 and 0.5 molar ratios) nanocomposites through a one-step sol-gel process in the presence of a triblock copolymer as a structure-directing agent. The prepared oxides were used as catalysts in the CO2 hydrogenation via Fischer-Tropsch reactions for the production of valuable hydrocarbons. Among the catalysts, the 0.05MnFe catalyst performed best under the selected reaction conditions: a reaction temperature of 340 degrees C, overall pressure of 20 bar, reactant mixture of 23% CO2/69% H2/8% N-2 and flow rate of 20 mL min(-1). This catalyst provided a much higher conversion of CO2 to hydrocarbons (63.2% C-2-C-5, 3.9% to C6+ and 3.6% to oxygenates) and the lowest levels of CO and methane formation among the xMnFe series. Moreover, 0.05MnFe was the only catalyst with a mesoporous structure, and it had a substantially lower reduction temperature than did the other members of the series. The enhanced catalytic activity of the 0.05MnFe catalyst, which contains only a small amount of Mn, appears to result primarily from its high specific area and relatively easy reduction. (C) 2014 Elsevier B.V. All rights reserved.