Porous inorganic oxide materials prepared by non-ionic surfactant templating route
First Claim
1. A synthetic, semi-crystalline inorganic metal oxide composition having at least one resolved x-ray reflection corresponding to a lattice spacing of 3 to 10 nm, a framework wall thickness of at least about 2 nm, framework confined pores between about 2 and 10 nm, an elementary particle size greater than 500 nm, and a specific surface area of 300 to 1200 square meters per gram.
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Abstract
A method for the preparation of new quasi-crystalline, porous inorganic oxide materials possessing uniform framework-confined mesopores in the range 2.0-10.0 nm and large elementary particle size of more than 500.0 nm. The method uses an interaction between various nonionic polyethylene oxide based surfactants (N°) and neutral inorganic oxide precursors (I¤) at ambient reaction temperatures. The materials formed exhibit semi-ordered arrays of well defined pores owing to the specific mechanism of self-assembly, large pore wall thicknesses of at least 2.0 nm producing highly stable materials and large particle sizes incorporating large numbers of pores. This (N° I°) templating approach introduces several new concepts to mesostructure synthesis. The application of the low-cost, non-toxic and biodegradable surfactants and ambient reaction temperatures, introduces environmentally clean synthetic techniques to the formation of mesostructures. Recovery of the template can be achieved through solvent extraction where the solvent may be water or ethanol.
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Citations
51 Claims
- 1. A synthetic, semi-crystalline inorganic metal oxide composition having at least one resolved x-ray reflection corresponding to a lattice spacing of 3 to 10 nm, a framework wall thickness of at least about 2 nm, framework confined pores between about 2 and 10 nm, an elementary particle size greater than 500 nm, and a specific surface area of 300 to 1200 square meters per gram.
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6. A synthetic, semi-crystalline inorganic metal oxide composition having at least one resolved x-ray reflection corresponding to a lattice spacing of 3 to 10 nm, a framework wall thickness of at least about 2 nm, framework confined pores between about 2 and 10 nm, an elementary particle size greater than 500 nm, and a specific surface area of 300 to 1200 square meters per gram prepared by reacting a mixture of a non-ionic poly(alkylene oxide) derived surfactant as a template (N°
- ) and a neutral inorganic metal oxide precursor (I°
), followed by hydrolysis and crosslinking of the inorganic oxide precursor to provide the composition. - View Dependent Claims (7, 8, 9, 10, 11, 15, 16, 17, 18, 19, 20, 21, 24, 25, 27, 28, 29, 30, 31, 32, 33, 34, 35)
- ) and a neutral inorganic metal oxide precursor (I°
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36. A method for the preparation of a synthetic semi-crystalline inorganic oxide composition which comprises:
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(a) forming a solution by providing a mixture of (i) a neutral inorganic oxide precursor (I°
) containing at least one element selected from the group consisting of di-, tri-, tetra-, penta- and hexavalent elements and mixture thereof;
(ii) a non-ionic poly(alkylene oxide) surfactant (S°
) as a template; and
(iii) a hydrolyzing agent;(b) mixing the solution to form a gel containing the composition; (c) separating at least some of the hydrolyzing agent and the surfactant from the gel; and (d) optionally calcining the composition. - View Dependent Claims (37)
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38. A method for the preparation of a synthetic, semi-crystalline inorganic oxide composition which comprises:
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(a) preparing a solution of a neutral inorganic oxide precursor (I°
), containing at least one element selected from the group consisting of di-, tri-, tetra-, penta- and hexavalent elements and mixtures thereof with stirring and optionally aging the inorganic oxide precursor (I°
) solution;(b) preparing a homogeneous solution of a nonionic poly(alkylene oxide) surfactant (S°
) as a template in a hydrolyzing agent, and optionally in a co-solvent, by stirring it at a temperature between about minus 20° and
plus 100°
C;(c) mixing of the solutions of steps (a) and (b) at a temperature between about minus 20° and
plus 100°
C to form a gel which is aged for at least about 30 minutes to form the composition;(d) separating at least some of the hydrolyzing agent and surfactant from the composition; and (e) optionally calcining the composition. - View Dependent Claims (39, 40, 41, 42, 43, 44)
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45. A method for the preparation of a crystalline inorganic oxide composition which comprises:
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(a) preparing a homogeneous solution of nonionic poly(ethylene oxide) surfactant as a template (N°
) in a lower alkyl alcohol solvent by mixing at ambient temperature;(b) adding an inorganic metal precursor to the solution of step (a) at ambient temperature under stirring for at least 30 minutes to form a homogeneous solution; (c) slowly adding a solution of a hydrolyzing agent to the homogeneous solution to form a gel as a first precipitate in the aqueous solution; (d) aging of the first precipitate with stirring; (e) redispersion of the first precipitate in a lower alkyl alcohol; (f) aging the redispersion under stirring at ambient temperature for 16 to 48 hours to form a second precipitate; (g) separating the aqueous solution, lower alkanol and at least some of the template from the second precipitate by washing once with ethanol; and (h) drying the second precipitate in air at ambient temperature to form the composition. - View Dependent Claims (46, 47, 48, 49)
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50. A method for the preparation of synthetic, semi-crystalline inorganic silicon dioxide composition which comprises:
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(a) preparing a homogeneous aqueous solution of a nonionic poly(ethylene oxide) derived surfactant template (N°
) with mixing at ambient temperature;(b) adding an inorganic silica precursor to the solution of step (a) at ambient temperature with stirring to form a solid, precipitate; (c) aging of the precipitate with stirring at ambient temperature for between 16 and 48 hours; (d) separating the aqueous solution and template from the precipitate followed by washing once with deionized water; (e) drying the precipitated and separated precipitate in air at ambient temperature; (f) heat treating the air dried precipitate in air at least 373°
K. for at least 16 hours;(g) optionally removing any remaining template by solvent extraction from the heat treated precipitate; and (h) calcining the precipitate to remove any remaining template to cross-link the framework at between 673°
K. and 923°
K. in air for at least 4 hours to form the composition. - View Dependent Claims (51)
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Specification