Highly Selective Supported Alkali Chloride Catalysts for the Oxidative Dehydrogenation of Ethane

Binary, ternary and quaternary molten eutectic alkali chloride catalysts, supported on mildly redox active oxides, were investigated for the oxidative dehydrogenation of ethane. The influence of different support oxides, on the catalytic performance, as well as that of different anions (bromide vs. chloride) and cations in a chloride eutectic system were studied. Metal oxides which react with chlorides are not suitable and lead to substantial deactivation. Especially supports forming volatile chlorides induce irreversible chloride depletion. Bromides catalyze oxidative dehydrogenation of ethane with higher rates, but lower olefin selectivities, highlighting the similarities and differences of Cl- and Br- in the redox cycle. Two catalysts were identified having olefin selectivities up to 98 % at 70 % ethane conversion, which ranges among the highest selectivities reported for ethane ODH.