CONTROLLED REACTION OF ACTIVE CARBONS WITH AIR AT 350-DEGREES-C .1. REACTIVITY AND CHANGES IN SURFACE-AREA

Two activated carbons prepared from almond shells and olive stones were reacted with air at 350°C to different percentages burn-off. The reactivity was studied in the temperature range 350-500°C where the reaction is relatively slow. The activated carbon from almond shells is more resistant to the reaction with air and the activation energy of that reaction is 101 kJ mol-1. The adsorption of N2 at 77 K has been used to characterize the adsorptive properties and surface area of all the obtained products, which have high surface areas (around or above 1000 m2 g-1). The gas adsorption results, together with mercury porosimetry have allowed a study of the variation of surface area and porosity as a function of the burn-off. In any case, the exposure of the active carbons to air at 350°C for several days does not considerably affect their adsorptive properties even for a weight loss up to 50%. © 1979.