Preparation of mesoporous carbon by freeze drying

Resorcinol-formaldehyde (RF) cryogels were synthesized by sol-gel polycondensation of resorcinol with formaldehyde and freeze drying with t-butanol. The cryogels were characterized by nitrogen adsorption and density measurements. Their porous properties were compared with those of RF aerogels prepared by supercritical drying with carbon dioxide. RF cryogels were mesoporous materials with large mesopore volumes >0.58 cm(3)/g. Although surface areas and mesopore volumes of the cryogels were smaller than those of the aerogels, the cryogels were useful precursors of mesoporous carbons. Carbon cryogels were obtained by pyrolyzing RF cryogels in an inert atmosphere. Carbon cryogels were mesoporous materials with high surface areas >800 m(2)/g and large mesopore volumes >0.55 cm(3)/g. When pyrolyzed, micropores are formed inside the cryogels more easily than inside the aerogels. (C) 1999 Elsevier Science Ltd. All rights reserved.