Silica foam compositions

A process for the preparation of a mesopoeous to small macroporous cellular silica foam composition with interconnected cells joined at nexus which comprises:

• (a) providing an aqueous mixture of a surfactant and an orgainic co-solvent which swells the surfactant as emulsifying agents;
• (b) providing a solution of a water soluble silicate;
• (c) providing an acid in an amount sufficient to cause precipitation of silica from the silicate solution at a pH between about 5.0 to 9.0;
• (d) combining the reagents in parts (a), (b) and (c) at a temperature greater than −20° C.;
• (e) allowing the reaction mixture of step (d) to age for a minimum time of 5 minutes at one or more temperatures above −20° C.;
• and
• (f) recovering the precipitated product from the solution;
• wherein the cellular silica foam composition in uncalcined form derived from a water soluble silicate is selected from the group consisting of sodium silicate, potassium silicate, alkylammonium silicate with interconnected cells joined at nexus defining cellular pores with open windows between the cellular pores and with SiO4, tetrahedral crosslinked to four adjacent silicon sites (Q4), to three adjacent silicon sites (Q3), and to two adjacent silicon sites (Q2), the ratio of Q4/(Q3+Q2) being greater than the ratio when the silica foam is derived from tetraethylorthosilicate and between 2.5 and 8.