Patent ID: 6103209
Filing Date: 2000-08-15
Classification: C01B

Abstract:
A process for preparing porous spherical silica particles, comprising:(a) hydrolyzing a silicon alkoxide in an aqueous media at a temperature of less than or equal to 40.degree. C. in the presence of an acid selected from the group consisting of a mineral acid and an organic acid form a colloidal silica solution having a pH of 1.5 to 3;(b) mixing the resulting colloidal silica solution from step (a) with an organic medium comprising at least one monofunctional alcohol having 8 or more carbon atoms, said monofunctional alcohol having a viscosity of greater than or equal to 8 cps and a dielectric constant greater than 4;(c) emulsifying the resulting mixture from step (b) at a temperature of 5 to 50.degree. C.;(d) contacting at a temperature of 5 to 50.degree. C. the resulting emulsion from step (c) with a basic solution comprising said monofunctional alcohol used in step (b) and a base soluble in said monofunctional alcohol to form a gel; and(e) heating the resulting gel from step (d) in the presence of said basic solution of step (d) at a temperature of 50 to 140.degree. C. for 2 to 16 hours;wherein the process prepares porous spherical silica particles having:an average diameter of 10 to 100 micrometers;a monodispersion degree of less than or equal to 2.5,a specific surface area of 200 to 600 m.sup.2 /g,a specific pore volume larger than 1 cm.sup.3 /g, andan average pore volume of 80 to 250 .ANG..