Enhanced conversion of CO2 with a mixed system of metal oxide and carbon

An endothermic chemical system composed of pulverized metal oxide and carbon has been investigated with a view to utilizing waste heat and carbonaceous compounds effectively. Oxides of Cu and Mn and also MMn2O4 (M = Li or Mg) were used. In an N2-gas stream, the metal oxide was reduced by reaction with carbon which was concurrently oxidized to generate CO and CO2, i.e. MOx + δC → MOx-δ + δCO. The process may be referred to as an activation step of the metal oxide phase. The activated metal oxide may be used for the effective reduction of CO2 to CO by the reverse reaction MOx−δ + δCO2 → MOx + δCO. LiMn2O4 as starting material showed the most rapid rates for both the activation and reduction steps at 700°C. The material was reduced to the Li-containing MnO phase in the activation step, which was also reactive for CO formation from CO2. These processes involving the Li+-containing MnO can be repeated until carbon is completely used up to produce CO at 700°C.