Patent ID: 7216509
Filing Date: 2007-05-15
Classification: C01B,C03B,C03C,Y02P

Abstract:
1. Sol-gel process for the production of tridimensional dry gels having all of the three lateral dimensions higher than about 2 cm, comprising the operations of: preparing a composition A comprising pyrogenic silica powder and an aqueous solution of an acid, such that the molar ratio H preparing a composition B comprising silica powder and an aqueous solution of a base not containing metallic cations, such that the molar ratio H forming a homogeneous composition C by mixing composition A and composition B in such a ratio that the molar ratio between silica from composition A and silica from composition B is between about 1:2 and 3:1, and whereby the pH of composition C is between 1 and 5 and the molar ratio H allowing gelation of composition C to obtain a wet gel; substituting water present in pores of the gel with a non-protic liquid miscible with water; drying the gel by evaporation or supercritical extraction of the non-protic liquid.