ELECTROCHEMICAL NATURAL-GAS CONVERSION TO MORE VALUABLE SPECIES

The electrochemical oxiative dimerization of methane to give C2 hydrocarbon species was investigated in solid oxide fuel cells possessing the general configuration anode CH4,electrocatalyst/ZrO2(8 m/o Y2O3)/La0.9Sr0.1MnO3,O2(air) Perovskite anode electrocatalysts shown to possess activity toward promoting the subject reaction included Sm0.5Ce0.5CuO3, Tb0.8Sm0.2CuO3, Gd0.9Th0.1CuO3, Gd0.9Na0.1MnO3, and Th0.8Yb0.2NiO3. Maximum partial faradaic current densities at active perovskite anode electrocatalysts for promoting the subject reaction were found to be directly correlatable to their calculated oxygen binding energies on the perovskite surface, where increasing binding energies were found to favor higher rates for electrochemical partial methane oxidation. Increasing surface oxygen binding energies at perovskite anode electrocatalysts were found to correlate with increasing perovskite lattice free volumes with electrochemical measurements, supporting increasing surface oxygen binding energies and perovskite lattice-free volumes as leading to enhanced rates for the subject reaction. As a consequence, synergism was found between experimentally determined perovskite anode electrocatalyst activities, their calculated surface oxygen binding energies, and lattice ionic-free volumes.