Features of high-temperature behavior in NdCaCoO4-the catalyst of the partial oxidation of methane to syngas

The peculiarities of the high-temperature (373-1173 K) behavior and transport properties of NdCaCoO4, which is a highly active and selective catalyst of the partial oxidation of methane to syngas, were considered. A relationship between its thermal and electrophysical properties and the structure and defectiveness of the oxygen sublattice was found. The electric conductivity of this compound, which is a two-dimensional analog of perovskite, was found to be almost independent of the oxygen pressure ( atm) and to increase with temperature, reaching similar to 100 S/cm at 1173 K. The temperature dependence of the conductivity of the n-type semiconductor NdCaCoO4 has two thermoactivation regions (373-573 and 573-873 K), in which the activation energy is almost doubled (0.46 and 0.81 eV, respectively). The discovered tendencies that determine the unique catalytic properties of this material are probably due to the change in the energy spectrum of this compound. The hypothetical reasons for this change are discussed.