Preparation of mesoporous carbon by freeze drying

Resorcinol-formaldehyde (RF) cryogels were synthesized by sol-gel polyconde nsation of resorcinol with formaldehyde and freeze drying with t-butanol. T he cryogels were characterized by nitrogen adsorption and density measureme nts. Their porous properties were compared with those of RF aerogels prepar ed by supercritical drying with carbon dioxide. RF cryogels were mesoporous materials with large mesopore volumes >0.58 cm(3)/g. Although surface area s and mesopore volumes of the cryogels were smaller than those of the aerog els, the cryogels were useful precursors of mesoporous carbons. Carbon cryo gels 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 forme d inside the cryogels more easily than inside the aerogels. (C) 1999 Elsevi er Science Ltd. All rights reserved.