CO, Adsorption Techniques On High Surface Area Activated Carbons

For years the subject of CO, adsorption on activated carbons has been both challenged and supported. The question remains whether or not CO, is a valid adsorbate for characterizing pore structures of activated carbons. The predominance of nitrogen adsorption as a routine experimental technique for BET surface area approximations has more or less overshadowed the limitations of this technique in terms of activated diffusion phenomena[l]. As a result, it is thought that nitrogen adsorption at 77K generally underestimates the surface area of coals[l]. In some super-activated carbons, CO, is an attractive adsorbate for characterization due to its small molecular diameter and it's access to supermicropores. Although CO, adsorption models are not completely understood, for particular cases in which N, adsorption may be problematic or inconclusive, CO, adsorption may offer additional pore structure i ?formation. The purpose of this communication is to address the concept of CO, adsorption phenomena experimentally and conceptually. Experimental data are compared for CO, adsorbed onto very high surface area activated carbons. From this information, optimal experimental conditions are theorized on the basis of ease and understanding. It is hoped that an adsorption procedure involving the benefits of N, and CO, together will provide insight into the pore structures of very high surface area activated carbons.