Carbon Dioxide Reforming of Methane using an Isothermal Redox Membrane Reactor

The continuous production of carbon monoxide (CO) and hydrogen (H₂) by dry reforming of methane (CH₄) is demonstrated isothermally using a ceramic 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 membrane and the partial oxidation of CH₄ with the lattice oxygen to form 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 micromol _CO   s^-1 from CO₂, 3.77 micromol_H₂ g^-1 s^-1 from CH₄ , and CO from CH₄ at approximately the same rate as CO from CO₂. 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) using electronic structure theory to understand how CO₂ reduction limits dry reforming of methane using LSCF and to show how the CO₂ conversion can be increased by using advanced redox materials such as La_0.5Sr_0.5MnO_3-δ and La_0.5Sr_0.5Mn_0.5Co_0.5O_3-δ .