| 摘要 |
Process for the preparation of a micro-mesoporous gel consisting of a silica matrix in which one or more metal oxides are possibly dispersed comprising: (a) subjecting to hydrolysis and gelification a tetra-alkylorthosilicate with an alkyl-trimethylammonium hydroxide having the formula R(CH3)3N-OH, wherein R is selected from n-butyl, n-pentyl, n-hexyl and n-heptyl, possibly in the presence of one or more metal compounds, the molar ratios in this mixture being: R-OH/SiO2=0-10; R(CH3)3N-OH/SiO2=0.05-0.4; H2O/SiO2=5-40; metal oxides/SiO2=0-0.02; whereas the ratio H2O/R(CH3)3N-OH varies according to the number of carbon atoms in the alkylic chain R as follows: R=n-butyl, H2O/R(CH3-)3N-OH<35; R=n-pentyl, H2O/R(CH3)3N-OH<70; R=n-hexyl, H2O/R(CH3)3N-OH<102; R=n-heptyl, H2O/R(CH3)3N-OH<136; (b) subjecting the gel or solid obtained in step (a) to drying and calcination.
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