Inhibition Effect of Coexisting Gas on CO2 Gasification of Ca-Loaded Coal Char

Synopsis: — The CO₂ gasification behavior of Ca-loaded Yallourn brown coal char was investigated in the presence of H₂ or CO with a thermal balance. The chemical form of Ca catalyst was in situ analyzed with a high temperature X-ray diffraction. In addition, oxygen containing-compounds on Ca-loaded char were evaluated with transient kinetics and temperature programmed desorption techniques. On the basis of these results, the mechanisms of H₂ and CO inhibition on Ca-catalyzed carbon gasification were discussed. It was found that the presence of H₂ suppresses the formation of surface oxygen containing-compounds as reaction intermediate. Therefore, H₂ inhibition can be attributed mainly to the adsorption of H₂ an Ca catalyst or on carbon surface in contact with Ca catalyst. As a result, the following catalytic processes are disturbed; the adsorption of _CO2 on Ca catalyst, and the formation of CaCO₃-C complexes. The temperature dependence of CO inhibition was quite different form the case of H₂ inhibition, and this implies that the mechanism may be different in the two inhibition cases.