REACTION OF GRAPHITE WITH CARBON DIOXIDE AND WITH HYDROGEN

The reaction of graphite with carbon dioxide at temperatures between 650 and 870 deg C and at pressures between 1 and 30 atm appears to be a simpler process than that shown for more reactive low temperature chars. The rate of formation of carbon monoxide in g-mole min/sup -1/ g/sup -1/ can be expressed by Rate = (k/sub 1/p/sub CO/sub 2/ )/(1 + k/sub 2/p/sub CO/), where k/ sub 1/ and k/sub 2/ are constants and p/sub CO/sub 2/ and p/sub CO/ are the partial pressures of carbon dioxide and carbon monoxide respectively. The rate also appears to be related to the geometric surface area and is unaffected by the pore structure. For carbons prepared at temperatures in excess of about 1500 deg C, the rate tends to limiting value for reaction at a given temperature and pressure and tends to become independent of the nature of the carbon. The reaction mechanism of graphite with hydrogen appears to be independent of the nature of the carbon, only the rate constants for the process being affected. (auth)