Effect of Pd doping in (Fe/Ni)/CeO2 catalyst for the reaction path in CO2 oxidative ethane dehydrogenation/reforming

Highlights: • Taking into account the value-added conversion of C₂H₆ and the utilization of CO₂. • The selectivity of ethylene on the Pd–Fe₆/CeO₂ catalyst is over 80%. • Pd doping increases energy barrier of CO₂-assisted dry reforming for Ni catalyst. • Doping of Pd forms double active structure with Fe and alloy structure with Ni. The catalytic reaction of C₂H₆ with CO₂ provides an opportunity to use shale gas and the greenhouse gas as source materials to produce ethylene through oxidative dehydrogenation or produce syngas through dry reforming. In this work, the reaction characteristics of ethane with CO₂ on Fe/Co/Ni/Cu monometallic catalysts and Pd-doped bimetallic catalysts were studied through activity test, kinetic analysis, catalyst characterization and DFT calculation. It is found that Pd–Fe₆/CeO₂ has a high and stable C₂H₄ selectivity of 80.4%, which is suitable for oxidative dehydrogenation reaction, while Ni₆/CeO₂ has a large ethane/CO₂ conversion and a high CO selectivity of 96.5%, which is suitable for dry reforming reaction. For Fe-based catalyst, the doping of Pd form double active component structure. It only reduces the energy barrier of ethylene formation and CO₂ direct activation to provide O∗, but also increases the energy barrier of ethylene deep dehydrogenation, thus increasing the conversion of reactants and selectivity of C₂H₄. For Ni-based catalysts, the doping of Pd forms the alloy structure, which reduces the energy barrier of O∗-assisted dehydrogenation reaction and increases the conversion of reactants, but increases the energy barrier of C–C bond cleavage and CO₂ activation reaction, which reduces the selectivity of reforming to syngas.