Metal-oxide-catalyzed CO2 gasification of coal using a solar furnace

Metal-oxide-catalyzed CO2 gasification of coal was demonstrated in small packed-bed and fluidized-bed reactors using a solar furnace simulator, for the purpose of converting solar high-temperature heat to chemical fuels. The catalytic activities of In2O3 and ZnO were investigated because used In2O3 or ZnO catalyst may be separated from remaining coal ash by In2O or Zn evaporation at high temperatures and at a reducing atmosphere. Bituminous coal with or without the metal-oxide catalyst in the quartz-tube reactor was directly irradiated by the concentrated Xe-lamp beam and CO2 was fed to the reactor at pCO(2) = 1.0. In the packed-bed reactor, In2O3 and ZnO much improved the chemical coal conversion by about 4-5 and 2-3 times at the catalyst loading of 17 wt %-In and 30 wt %-Zn in the coal-metal-oxide mixture, respectively, at temperatures around 1000-1400 K. In the fluidized-bed reactor at a small catalyst loading (8-10 wt %-metal in the coal-metal-oxide mixture) and at 1073-1163 K, In2O3 catalytically increased the coal-conversion rate by 3 times but ZnO scarcely showed the catalytic activity. This metal-catalyzed coal gasification process offers the efficient solar production of the syngas calorifically upgraded by solar energy.