Mesoporous hexaaluminate prepared by carbon template method and having large specific surface area and preparation method of hexaaluminate

Abstract

The invention relates to the field of preparation of hexaaluminate materials, in particular to mesoporous hexaaluminate prepared by a carbon template method and having a large specific surface area and a preparation method of the hexaaluminate. The preparation method comprises the following steps of: 1) pretreating carbon materials, and dispersing the carbon materials into a solvent to obtain mesoporous carbon suspension; 2) dissolving an aluminum salt precursor and one or more of an alkaline-earth metal precursor, a rare-earth metal precursor and a transition metal precursor into the solvent to obtain a metal salt precursor solution; 3) adding the metal salt precursor solution into the mesoporous carbon suspension, stirring and drying by distillation to obtain a salt-carbon composite; 4) placing the salt-carbon composite in a labile nitrogen compound-containing aqueous solution, reacting, and washing, baking and roasting the obtained sample to obtain a hexaaluminate precursor-carbon composite; and 5) adding the hexaaluminate precursor-carbon composite into the metal salt precursor solution for impregnation, and finally performing thermal treatment and roasting to obtain the mesporous hexaaluminate having the large specific surface area.

Description

technical field [0001] The invention relates to the field of preparation of hexaaluminate materials. Specifically, the invention relates to a hexaaluminate with mesoporous high specific surface area prepared by a carbon template method and a preparation method thereof. Background technique [0002] Hexaaluminate is often used to catalyze the high-temperature combustion of methane, methane carbon dioxide reforming and N 2 O decomposition and other fields. Hexaaluminate available AAl 12 o 19 Indicates (A is alkali metal, alkaline earth metal or rare earth metal), which is a layered structure material in which the spinel formed by alumina is separated by the "mirror surface" composed of oxides of alkali metal or alkaline earth metal, and has a β-Al 2 o 3 Type or magnetoplumbite type structure, this special anisotropic layered structure endows hexaaluminate with outstanding high temperature thermal stability and thermal shock resistance, and can still maintain a high specifi...

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Problems solved by technology

[0003] The synthesis methods of hexaaluminate currently reported mainly include coprecipitation method, sol-gel method and inverse microemulsion method. The hexaaluminate prepared by different methods has great differences when used as a catalyst. Patents CN1698951A and CN101612572A discloses co-precipitation method to prepare hexaaluminate catalysts, which are used for light hydrocarbon combustion and N 2 O decomposition, this method is relatively simple, but the specific surface area of ​​the prepared hexaaluminate is small, and the catalyst performance is not high

CN101012066A adopts a urea combustion method, the calcination temperature is very high, and the uniformity of the obtained hexaaluminate particles is not good enough

[0005] At present, the preparation of inorganic nanomaterials by the template method is a relatively mature method, but when using the template method to prepare hexaaluminate with mesoporous high specific surface area, the synthesis of crystalline hexaaluminate-based mesoporous materials is much more complicated. The main difficulties in its synthesis are: first, the high hydrolysis polymerization rate of the metal salt precursor leads to excessive growth and polymerization of the inorganic network, making it difficult to form an organic-inorganic mesoporous phase; second, the valence change, Factors such as excessive crystallization of inorganic pore walls and removal of surfactants / templates (high-temperature roasting and solvent extraction) will destroy the target mesoporous structure; the third is the high crystallization temperature of hexaaluminate (about 1200 ° C), which is suitable for large For most hexaaluminate-based materials, the samples obtained at low calcination temperature often contain impurities. Although increasing the calcination temperature can reduce the amount of impurities, it will lead to excessive crystallization of the mesoporous pore walls, resulting in the collapse of the channels and the decrease of the specific surface area of ​​the sample. decrease

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