DETAILED DESCRIPTION What is claimed is: 1.
A process for the production of a silicic acid heteropolycondensate porous adsorbent, comprising: condensing (a) at least one hydrolysable silicic acid derivative corresponding to the general formula: SiR.
sub.
4 ( 1) wherein R represents a group selected from the group consisting of hydrogen, halogen, alkoxy and --NR'.
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2, wherein R' is hydrogen lower alkyl and combinations thereof, with the proviso that not all the radicals R are hydrogen; (b) at least one substituted silane corresponding to the general formula: SiR.
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n R".
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(4-n) ( 11) wherein R is as defined above, R" represents a group selected from the group consisting of alkyl, alkenyl, aryl and aralkyl and n is an integer of from 1 to 3; (c) optionally at least one functional silane corresponding to the general formula: SiR.
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n (R'''Y).
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(4-n) ( 111) wherein R is as defined above, R''' represents a group selected from the group consisting of alkylene, phenylene, alkylphenylene and alkylenephenylene, Y represents a group selected from the group consisting of halogen, amino, anilino, aldehyde, keto, carboxy, hydroxy, mercapto, cyano, hydroxyphenyl, diazo, carboxylic acid alkyl ester, sulphonic acid (--SO.
sub.
3 H) and phosphoric acid (--PO.
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3 H.
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2) groups and n is an integer of from 1 to 3; and/or (d) optionally at least one compound selected from the group consisting of substantially involatile oxides soluble in the reaction medium and compounds of elements of Groups Ia to Va, IVb and Vb of the Periodic System forming a substantially involatile oxide in the presence of at least the quantity of water stoichiometrically required for hydrolysis and in an organic solvent in the presence of a condensation catalyst in a single stage until condensation is complete, the quantities in which components (a) to (d) are used being selected in such a way that the silicic acid heteropolycondensate formed contains, based on oxides, from 50 to 90% by weight of component (a), from 10 to 50% by weight of component (b), from 0 to 15% by weight of component (c) and from 0 to 40% by weight of component; and thereafter removing said organic solvent and drying said polycondensate, thereby producing a porous adsorbent having a porosity of from 15 to 35% and a BET surface area of from 40 to 1200 m
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Semiconductor manufacture 
