Dual Ni active sites mediated by In to separate ethane activation and oxidation for enhanced ethene production via chemical looping scheme

Chemical looping oxidative dehydrogenation (CL-ODH) opens a unique avenue to achieve highly efficient conversion of alkanes to value-added alkenes. The challenge lies in identical metal-oxo active sites responsible for both alkane activation and oxidation causing either insufficient activity or over-oxidation thus inferior ethene yield and productivity at relatively low temperature (< 650 °C). Herein, we designed a novel redox catalyst by the incorporation of main-group In (6NiInx/HY, x indicates the atomic ratio of In/Ni) which achieved more than 92 % ethene selectivity at 40 % ethane conversion and long-term stability at 600 °C with 0.22 mmol g−1 ethene productivity at 650 °C. This was because Ni2+ Lewis acid sites conducted catalytic dehydrogenation of ethane to ethene and hydrogen, and the Ni-O-In moiety outside HY framework enabled selective oxidation of hydrogen rather than ethene due to well-regulated Ni 3d electron densities leading to the reduction of adsorption for ethene thus decreasing over-oxidation.