(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. La0.6Sr0.4Co0.2Fe0.8O3-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 La0.5Sr0.5B0.5B’0.5O3-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 La0.5Sr0.5MnO3-δ and La0.5Sr0.5Mn0.5Co0.5O3-δ with lower oxygen vacancy stabilities. The developed principles may be useful for the rational design of advanced redox materials for solar-driven processes.