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초록

Energy-efficient chemical looping-based oxidative dehydrogenation of ethane (CL-ODH, C2H6 + 1/2O(2) = C2H4 + H2O) was composed of the reduction step of metal oxides by ODH reaction to produce ethylene and successive CO2 activation (oxidation step) on the partially reduced metal oxides to produce CO or by a reverse Boudouard reaction with surface coke precursors (C + CO2 = 2CO). The optimization of preparation methods of FeOx-TiO2 catalysts was investigated by using hydrothermal (HT), coprecipitation (CP), and impregnation (IM) method, separately. The FeTiOx(HT) catalyst synthesized by hydrothermal method showed the stable preservation of the active FeTiO3 phases on the rutile TiO2 phase with moderate ethylene yield of 4.5% (higher C2H6 conversion of 18.0%), where Fe phases were easily transformed between the metallic Fe-0 and oxidized Fe2+ phase during the oxidative C2H6 dehydrogenation (reduction reaction) step and Fe2+ and Fe3+ phase during CO2 activation (oxidation reaction by reverse Boudouard reaction) step after three cyclic CL-ODH reactions. The larger amount of surface oxygens on the FeTiOx(CP) was responsible for an increased selectivity to COx byproducts of 81.5% compared to the more active and selective FeTiOx(IM) and FeTiOx(HT) due to larger number of electrophilic surface oxygens for facile complete oxidation activity.

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