Preparation of activated carbon by chemical activation with ZnCl2

Several series of activated carbons have been prepared by chemical activation of peach stones with ZnCl2 in order to show the effect of variables such as a precursor particle size, extent of impregnation, impregnation method, and carbonization temperature on surface area, porosity, and bulk density of the resulting activated carbons. The adsorption isotherms of n-butane at 273 K on all carbons prepared are of type I, with a defined plateau, the extent of which is a function of the preparation conditions. The main factor affecting the surface area and the micropore size distribution is the amount of Zn introduced in the precursor during impregnation. Partial gasification in CO2 of the carbons produces a considerable developing of surface area and porosity, maximum for burn-offs around 60–70%. In this way, it is possible to prepare activated carbons with very high surface area (larger than 3000 m2/g) compatible with a granular form and reasonable bulk density.