CaO–ZnO Catalyst for Selective Conversion of Methane to C2 Hydrocarbons Using Carbon Dioxide as the Oxidant

A binary catalyst of CaO–ZnO is effective for the selective conversion of CH4 to C2 hydrocarbons using CO2 as the oxidant. C2 selectivity approaches 80% with a C2 yield of 4.3% over the catalyst with a Ca/Zn ratio of 0.5 at 875°C. The lattice oxygen of the CaO–ZnO converts CH4 mainly to H2 and CO. The presence of CO2 forms a new oxygen species, which is active and selective for the conversion of CH4 to C2 hydrocarbons. The CaO component in the catalyst enhances the adsorption of CO2 and thus suppresses the reaction involving the lattice oxygen. The reduced Zn site is suggested to activate CO2.