(699c) Methane Partial Oxidation and Dry Reforming to Syngas Using the La0.9Ca0.1FeO3-? Mixed-Conductor

One of the most promising technologies for carbon dioxide (CO₂) Capture and Sequestration is oxyfuel combustion, i.e. the use of pure oxygen in the combustion of fossil fuels. The major energy penalty in oxyfuel combustion comes from oxygen production. The current technology uses cryogenic methods and this process is energy intensive; it can lead to approximately 25% reduction in the net efficiency of a power plant.

Mixed ionic-electronic conducting (MIEC) membranes can serve as a better substitute. These materials have the potential of decreasing the energy consumption for oxygen separation significantly given that they operate under an oxygen chemical potential difference between the two sides. In addition, due to both oxygen separation and reaction (process intensification), chemical processes become simpler and this leads to a lower operating cost. MIEC materials are becoming popular in the energy sector, especially for chemical conversion processes.

A stable oxygen-conducting membrane under reducing conditions is La_0.9Ca_0.1FeO_3-δ (LCF). Our study investigates the performance of LCF in applications combining oxyfuel combustion, CO₂ reuse and syngas production under a reactive environment using methane-carbon dioxide mixtures in the oxygen lean side. In the presence of fuel, experimental measurements show that the oxygen flux through the membrane increases by one order of magnitude compared to the non-reactive case due to heterogeneous reactions of hydrogen and carbon monoxide with lattice oxygen ions. These surface reactions produce additional steam and carbon dioxide which further increase the syngas yield by reforming methane in the gas-phase. The aforementioned performance enhancement is accompanied by significant reuse of CO₂. Our results suggest that the performance of LCF is limited by the surface reactions on the fuel side and hence, we show that addition of nickel nanoparticles on the fuel side increase the oxygen permeation and the methane performance significantly by reducing the surface polarization resistance.