SURFACE-MODIFIED MIXED OXIDE PREPARED BY HIGHLY THERMAL DECOMPOSITION AND ITS PREPARATION

Surface-modified, pyrogenically produced mixed oxides contain two or more components from SiO2, Al2O3, TiO2, ZrO2, Re2O3, Nb2O5, V2O5, WO3, SnO2 and GeO2, which were surface modified with one or more of cpds. (a)-(m) below. (a) organosilanes of formula (I): (RO)3Si(CnH2n+1) (I) R = alkyl; and n = 1-20; (b) organosilanes of formula (II): R'x(RO)ySi(CnH2n+1) (II) R' = alkyl; x, y = 1 or 2; and x+y = 3; (c) halogenorganosilanes of formula (III): X3Si(CnH2n+1) (III) X = Cl or Br; (d) halogenorganosilanes of formula (IV): X2(R')Si(CnH2n+1) (IV); (e) halogenorganosilanes of formula (V): X2(R')2Si(CnH2n+1) (V) (f) organosilanes of formula (VI): (RO)3Si(CH2)m-R' (VI) m = 0 or 1-20; R' = methyl, aryl e.g. (substd.) phenyl, -C4F9, -OCF2-CHF-CF3, -C6F13, -O-CF2CHF2, -NH2, -N3, -SCN, -CH=CH2, -OOC(CH3)C=CH2, -OCH2-CH(O)CH2, -NH-COO-CH3, -NH-COO-CH2CH3, -NH-(CH2)3Si(OR)3 or -Sx-(CH2)3Si(OR)3; (g) organosilanes of formula (VII): (R")x(RO)ySi(CH2)m-R' (VII) R" = alkyl; R' = R' as for (VI); x, y = 1 or 2; and x + y = 2; (h) halogenorganosilanes of formula (VIII): X3Si(CH2)m-R' (VI) R' = R' as for (VI); (i) halogenorganosilanes of formula (IX): (R)X2Si(CH2)m-R' (IX) R' = R' as for (VI); (j) halogenorganosilanes of formula (X): (R)2XSi(CH2)m-R' (X) R' = R' as for (VI); (k) silazanes of formula (XI): R'R2Si-N(H)-SiR2R' (XI) R' = R' as for (VI); (1) cyclic polysiloxanes of the type D 3, D 4 or D 5, e.g. octamethylcyclotetrasiloxane of formula (XII) = D 4: (m) polysiloxanes and silicone oils of formula (XIII): m, n, u = 0 or any integer; Y = H, methyl, CnH2n+1, Si(CH3)3, Si(CH3)2H, Si(CH3)2OH, Si(CH3)2(OCH3) or Si(CH3)2(CnH2n+1); and R, R', R", R"' = H, alkyl, aryl or (CH2)n-NH2. Also claimed are: (1) a process for the prepn. of the above surface-modified mixed oxides; and (2) the above surface-modified mixed oxides and the above process as described in the disclosure with partic. reference to the examples.