REACTIVITY OF OXYGEN-DEFICIENT MN(II)-BEARING FERRITES (MNXFE3-XO4-DELTA, 0-LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-1, DELTA-GREATER-THAN-0) TOWARD CO2 DECOMPOSITION TO CARBON

The reduction of CO2 to Carbon was studied in oxygen-deficient Mn(II)- bearing ferrites (MnxFe3-xO4-delta, 0 less-than-or-equal-to x less-tha n-or-equal-to 1, delta > 0 at 300-degrees-C. They were prepared by red ucing Mn(II)-bearing ferrites with H-2 gas at 300-degrees-C. The oxyge n-deficient Mn(II)-bearing ferrites showed a single phase with a spine l structure having an oxygen deficiency. The decomposition reaction of CO2 to carbon was accompanied by oxidation of the oxygen-deficient Mn (II)-bearing ferrites. The decomposition rate slowed when the Mn(II) c ontent in the Mn(II)-bearing ferrites increased. A Mossbauer study of the phase changes of the solid samples during the H2 reduction and CO2 decomposition indicated the following. Increases in the Mn(II) conten t lowered the electron conductivity of the Mn(II)-bearing ferrites. In creases in the oxygen deficiency, delta, contributed to an increase in electron conductivity and suggested that electron conduction due to t he electron hopping determines the reductivity of CO2 to carbon by the donation of an electron at adsorption sites.