Chemical looping syngas from CO2 and H2O over manganese oxide minerals

Rather than sequestering carbon dioxide from the exhaust of chemical looping combustion reactors, together with the water, it could be used as a source of syngas. For the first time, we split water to hydrogen and carbon dioxide to carbon monoxide with a manganese ore. Specific CO production is 10-100 times higher than Sr, Ce, and Fe doped perovskites and Y0.5Sr0.5MnO3 perovskites. At a contact time of 0.01 s and at temperatures ranging from 810-960 degrees C the maximum specific CO production was 5.5 molkg-1. A combined kinetic-axial dispersion hydrodynamic model accounts for 97 % of the variance in the data assuming the reaction rate is first-order in CO2 and surface reduced sites and in equilibrium with the reverse reactiona first-order reaction in CO with surface oxidized sites. A second reaction accounts for the diffusion of surface oxygen to the bulk lattice. Hydrogen productivity peaked at 4.8 molkg-1 at 947 degrees C, which is twice as high as reported in previous studies on CoFe2O4 and Al2O3 in the hercynite cycle.