Abstract: Large sol-gel derived silicon-containing monoliths are prepared with the use of drying control chemical additives selected from the group consisting of glycerol, formamide, oxalic acid and acids of the formula C.sub.n H.sub.2(n-1) O.sub.2 N to control the ultrastructure of the gel solid and pore phases. Gelation, aging, drying, and densification of the sol-gel derived monoliths may be performed rapidly in tens of hours instead of tens of days without cracking, final densification at temperature of 800.degree. C. to 1200.degree. C. or less being possible. The silicon-containing monolith comprises a ternary SiO.sub.2 --B.sub.2 O.sub.3 --Na.sub.2 O system.

Abstract: A method of fabricating an ultraporous SiO.sub.2 containing gel monoliths having a predetermined mean pore size with narrow distribution of the size of the pores around the mean. A SiO.sub.2 containing sol is prepared while simultaneously controlling and preselecting the temperature, time and nature of aging solution, and drying the resultant gel to obtain an ultraporous SiO.sub.2 containing monolith having a predetermined mean pore size from about 10 .ANG. to about 400 .ANG. with narrow distribution of the size of pores around the mean and the resultant article.