Poly(silicic acid)

Abstract

Particulate, porous, water-insoluble amorphous poly(silicic acid) which is characterized by an average pore diameter of at least 100 A and a surface area of 500 to 850 m.sup.2 /g, by an average pore diameter of 50 A to about 300 A and a surface area of greater than 850 m.sup.2 /g, or by a pore volume of 1.5 ml/g to about 8.5 ml/g and a surface area of greater than 850 m.sup.2 /g; process for preparing particulate, porous, water-insoluble, amorphous poly(silicic acid) by acidifying an appropriate aqueous silicate solution, allowing the silicic acid thus formed to polymerize to poly(silicic acid), freezing the acidified solution, and thereafter thawing the acidified solution and isolating therefrom, washing, drying and recovering particulate poly(silicic acid), said process further characterized in that: (a) the amount of silicate in the aqueous silicate solution is such that the SiO.sub.2 content of the acidified solution is about 4 to 25 weight % and such that the acidified solution contains about 15 to 150 weight %, based on the weight of SiO.sub.2, of at least one water-soluble compound which is precipitable from the acidified solution at -10.degree. to -200.degree. C. and which is inert to the silicate, silicic acid and poly(silicic acid); (b) the aqueous silicate solution is acidified to a pH of about 3 to 9; and (c) the acidified solution is cooled to a temperature of about -10.degree. to -200.degree. C. until it is frozen to separate substantially all of the chemically unbound water as substantially pure ice and to precipitate water soluble compound within the pores of the poly(silicic acid) particles being formed.

Dependencies are inferred from the claim text.