(200d) CO2 Reforming of CH4 with an Isothermal Redox Membrane Reactor

The continuous production of CO and H₂ via dry reforming of CH₄ is demonstrated with an isothermal redox membrane in absence of additional catalysts. The reactor technology realizes the continuous splitting of CO₂ to CO on the inner side of a tubular ceramic membrane and the partial oxidation of CH₄ with the lattice oxygen to syngas on the outer side. La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ (LSCF) membranes evaluated at 840-1030°C yielded up to 1.27 μmol CO from CO₂ g^-1 LSCF s^-1, 3.77 μmol H₂ from CH₄ g^-1 s^-1, and CO from CH₄ at approximately the same rate as CO from CO₂. To understand how CH₄ activation limits CO₂ conversion with LSCF, we compute the free energy of the oxygen vacancy formation for La_0.5Sr_0.5B_0.5B’_0.5O_3-δ (B, B’ = Mn, Fe, Co, Cu) via electronic structure theory. Furthermore, we employ density functional theory to show how CO₂ conversion can be increased with advanced redox materials such as La_0.5Sr_0.5MnO_3-δ and La_0.5Sr_0.5Mn_0.5Co_0.5O_3-δ with lower oxygen vacancy stabilities. The developed principles may be useful for the rational design of advanced redox materials for solar-driven processes.