Chemical Looping‐Based Dehydrogenation of Ethane with Successive CO₂ Activation on Fe/TiO₂ Catalysts: Effects of Catalyst Preparation Method

Energy‐efficient chemical looping‐based oxidative dehydrogenation of ethane (CL‐ODH, C 2 H 6 + 1/2O 2 = C 2 H 4 + H 2 O) was composed of the reduction step of metal oxides by ODH reaction to produce ethylene and successive CO 2 activation (oxidation step) on the partially reduced metal oxides to produce CO or by a reverse Boudouard reaction with surface coke precursors (C + CO 2 = 2CO). The optimization of preparation methods of FeO x ‐TiO 2 catalysts was investigated by using hydrothermal (HT), coprecipitation (CP), and impregnation (IM) method, separately. The FeTiO x (HT) catalyst synthesized by hydrothermal method showed the stable preservation of the active FeTiO 3 phases on the rutile TiO 2 phase with moderate ethylene yield of 4.5% (higher C 2 H 6 conversion of 18.0%), where Fe phases were easily transformed between the metallic Fe 0 and oxidized Fe 2+ phase during the oxidative C 2 H 6 dehydrogenation (reduction reaction) step and Fe 2+ and Fe 3+ phase during CO 2 activation (oxidation reaction by reverse Boudouard reaction) step after three cyclic CL‐ODH reactions. The larger amount of surface oxygens on the FeTiO x (CP) was responsible for an increased selectivity to COx byproducts of 81.5% compared to the more active and selective FeTiO x (IM) and FeTiO x (HT) due to larger number of electrophilic surface oxygens for facile complete oxidation activity.