Preparation method of mesoporous nanocrystalline gamma-alumina powder
阅读说明：本技术 一种介孔纳米晶γ-氧化铝粉体的制备方法 (Preparation method of mesoporous nanocrystalline gamma-alumina powder ) 是由 李义涛 黄永锋 何鑫 胡聿明 余航 张宏清 唐火强 于 2018-07-19 设计创作，主要内容包括：本发明提供一种介孔纳米晶γ-氧化铝粉体的制备方法,包括：S1：将金属铝盐、表面活性剂I于溶剂中搅拌溶解,加入沉淀剂的水溶液,沉淀、老化,得到液体溶胶；S2：将上述液体溶胶过滤,用表面活性剂II洗涤,干燥、焙烧,得到γ-氧化铝粉体；所述制备方法通过两次使用不同的表面活性剂I和表面活性剂II,得到具有比表面积高、孔径大的γ-氧化铝粉体。所述γ-氧化铝粉体作为载体制成的蒽醌加氢催化剂,具有催化活性高和使用寿命长的优势。(The invention provides a preparation method of mesoporous nanocrystalline gamma-alumina powder, which comprises the steps of S1, dissolving metal aluminum salt and a surfactant I in a solvent by stirring, adding a water solution of a precipitator, precipitating and aging to obtain a liquid sol, S2, filtering the liquid sol, washing with a surfactant II, drying and roasting to obtain gamma-alumina powder, wherein the gamma-alumina powder with high specific surface area and large pore diameter is obtained by using different surfactants I and II twice.)
The preparation method of mesoporous nanocrystalline gamma-alumina powder is characterized by comprising the following steps:
s1: dissolving metal aluminum salt and a surfactant I in a solvent by stirring, adding a water solution of a precipitator, precipitating and aging to obtain liquid sol;
s2: and filtering the liquid sol, washing with a solution containing a surfactant II, drying and roasting to obtain the mesoporous nanocrystalline gamma-alumina powder.
2. The method for preparing mesoporous nanocrystalline gamma-alumina powder according to claim 1, wherein the surfactant I is selected from water-soluble amphoteric cellulose, quaternary ammonium type ammonium iodide, polyvinylpyrrolidone, polyethylene glycol, or at least two of Tween, and the surfactant II is selected from benzene sulfonamide compounds, polyoxyethylene diamine, octadecyl dimethyl tertiary amine, and or at least two of span.
3. The method for preparing mesoporous nanocrystalline γ -alumina powder according to claim 2, wherein the water-soluble amphoteric cellulose is selected from or a combination of at least two of propylene oxide dimethyltetradecyl ammonium chloride-carboxymethyl cellulose, propylene oxide trioctyl ammonium chloride-carboxymethyl cellulose, trimethyl lignin ammonium chloride-carboxymethyl cellulose, propylene oxide dimethyloctyl graft-cellulose sulfate, propylene oxide dimethyldodecyl graft-cellulose sulfate, and propylene oxide dimethyltetradecyl graft-cellulose sulfate, the quaternary ammonium type ammonium iodide is selected from N- [3- (p-perfluorononenoxybenzoyl) propyl ] -N, N-trimethyl ammonium iodide, the polyethylene glycol is selected from or a combination of at least two of polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 1000, polyethylene glycol 2000, polyethylene glycol 4000, polyethylene glycol 10000, and polyethylene glycol 20000, and the tween is selected from or a combination of at least two of tween 20, tween 40, tween 60 and tween 80.
4. The method for preparing mesoporous nanocrystalline gamma-alumina powder according to claim 2, wherein the benzenesulfonamide compound is selected from N-hydroxyethyl-N-methyl-4-perfluoroalkyleneoxy benzenesulfonamide, the structure of which is as shown in formula IThe following steps:
5. The method for preparing mesoporous nanocrystalline γ -alumina powder according to claim 1, wherein the surfactant I accounts for 0.1-20% of the aluminum metal salt by mass; the mass of the surfactant II accounts for 0.1-10% of the mass of the metal aluminum salt.
6. The preparation method of the mesoporous nanocrystalline gamma-alumina powder according to claim 1, wherein the aqueous solution of the precipitant is added by spraying, the spraying time is controlled to be 1-60 min, and the precipitant is or a combination of at least two of ammonia water, ammonium carbonate and urea.
7. The method for preparing mesoporous nanocrystalline γ -alumina powder according to claim 1, wherein the aging conditions are as follows: the aging temperature is 60-100 ℃, the aging time is 8-24h, and the rotating speed is 200-800 r/min.
8. The method for preparing mesoporous nanocrystalline γ -alumina powder according to claim 1, wherein the drying process is: firstly, vacuum drying for 8-12 h at 25-50 ℃, and then vacuum drying for 2-4 h at 110 ℃; the roasting temperature is 350-550 ℃, and the roasting time is 3-8 h.
9. The mesoporous nanocrystalline γ -alumina powder prepared by the method according to any one of claims 1 to 8 and .
10. The application of the mesoporous nanocrystalline gamma-alumina powder according to claim 9, wherein the mesoporous nanocrystalline gamma-alumina powder is used as a catalytic carrier for synthesizing hydrogen peroxide by an anthraquinone process.
Technical Field
The invention relates to the technical field of preparation methods of kinds of alumina, in particular to a preparation method of kinds of mesoporous nanocrystalline gamma-alumina powder, and the gamma-alumina powder is particularly suitable for a reaction for synthesizing hydrogen peroxide by an anthraquinone process as a carrier.
Background
Hydrogen peroxide (H)2O2) The method is mainly characterized in that a production method of the hydrogen peroxide is continuously developed, although the direct hydrogen-oxygen synthesis method is highly concerned at present, most of the hydrogen-oxygen synthesis method is in a laboratory stage, the current anthraquinone method is a main flow route of industrial production, the anthraquinone method mainly comprises three processes of hydrogenation, oxidation and extraction, wherein anthraquinone hydrogenation is the core of the whole process, and the process mainly uses a catalyst of mesoporous active alumina loaded with the noble metal palladium, so that the use efficiency of the noble metal palladium is improved, the preparation cost of the catalyst is reduced, the activity of the catalyst is improved, the selectivity of the catalyst is improved, and the key point of research is that the catalyst is high in price, the use efficiency of the alumina carrier is improved, the preparation cost of the catalyst is reduced, and the catalyst is high in activity and the selectivity of the alumina carrier, and the performance of the catalyst is high.
Chinese patent CN102583476A discloses dynamic hydrothermal methods for preparing mesoporous gamma-A12O3The method of (1), the method comprisingTaking a surfactant solution as bottom water, respectively adding inorganic aluminum salt and a precipitator to uniformly mix the inorganic aluminum salt and the precipitator, continuously stirring the mixed solution and crystallizing an autoclave for hydrothermal treatment, washing and roasting the obtained product after the reaction is finished to obtain mesoporous gamma-Al2O3The preparation method can effectively control the formation of an alumina precursor, and the crystallization time can be shortened to be within 24 hours, but the mesoporous gamma-alumina prepared by the method has lower specific surface area and pore diameter lower than 9nm, and the dynamic hydrothermal method needs higher pressure and high energy consumption, so preparation methods which can obtain alumina powder with high specific surface area, large pore diameter and lower energy consumption and are suitable for being used as a catalytic carrier are still needed to be developed at present.
Disclosure of Invention
Aiming at the problems of lower specific surface area, smaller aperture, higher energy consumption of the preparation method and the like of alumina powder in the prior art, the invention provides a preparation method of mesoporous nanocrystalline gamma-alumina powder, wherein the preparation method obtains gamma-alumina powder with high specific surface area and large aperture by using different surfactant I and surfactant II twice.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention provides a preparation method of mesoporous nanocrystalline gamma-alumina powder, which comprises the following steps:
s1: dissolving metal aluminum salt and a surfactant I in a solvent by stirring, adding a water solution of a precipitator, precipitating and aging to obtain liquid sol;
s2: and filtering the liquid sol, washing with a solution containing a surfactant II, drying and roasting to obtain the gamma-alumina powder.
Further , the aluminum metal salt is selected from aluminum nitrate nonahydrate, aluminum chloride, of aluminum sulfate or a combination of at least two of the foregoing.
Further , the solvent is selected from or a combination of at least two of water, methanol, ethanol, isopropanol, and isobutanol.
In the preparation method provided by the invention, the surfactant I can play a pore-forming role or a pore-channel maintaining role in the drying and roasting process. Specifically, the surfactant I is easily soluble in water and an organic solvent, a microemulsion interface can be effectively formed by means of different affinities of the surfactant I and the water and the organic solvent, the contact time of an ammonium carbonate aqueous solution and an aluminum solution is prolonged, the formation of nanocrystalline particles is facilitated, meanwhile, the surfactant I has high molecular weight and special steric hindrance, original pores of the aluminum oxide powder are greatly filled, and the original pores are kept after the aluminum oxide powder is roasted, so that the pore-forming effect is indirectly achieved.
, the surfactant I is selected from water-soluble amphoteric cellulose, quaternary ammonium iodide, polyvinylpyrrolidone, polyethylene glycol, and of Tween or a combination of at least two thereof.
Because the water-soluble amphoteric cellulose has larger steric hindrance, the surfactant I is particularly preferably selected from the water-soluble amphoteric cellulose or the combination of the water-soluble amphoteric cellulose and of quaternary ammonium type ammonium iodide, polyvinylpyrrolidone, polyethylene glycol and tween.
, the water-soluble amphoteric cellulose is selected from or a combination of at least two of propylene oxide dimethyltetradecyl ammonium chloride-carboxymethyl cellulose, epoxypropyltrioctyl ammonium chloride-carboxymethyl cellulose, trimethyl lignin ammonium chloride-carboxymethyl cellulose, propylene oxide dimethyloctyl graft-cellulose sulfate, propylene oxide dimethyldodecyl graft-cellulose sulfate, propylene oxide dimethyltetradecyl graft-cellulose sulfate.
, the quaternary ammonium type ammonium iodide is selected from N- [3- (p-perfluorononenoxybenzoyl) propyl ] -N, N, N-trimethyl ammonium iodide.
, the polyethylene glycol is selected from or at least two of
, the mass of the surfactant I is 0.1-20%, more preferably 1-15%, particularly preferably 2-10%, for example, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10% of the mass of the aluminum metal salt, but not limited thereto.
In the preparation method provided by the invention, the surfactant II is dissolved in an organic solvent but not dissolved in water, and the solution containing the surfactant II is used for washing the alumina liquid sol, so that redundant water in the filter cake can be effectively replaced, and the agglomeration phenomenon can be effectively reduced by reducing the water content of the filter cake, so that the specific surface area of the alumina is effectively improved, and the original pore diameter of the alumina is kept unchanged.
The solvent of the washing surfactant II-containing solution is the same as the solvent described in step S1, and the mass content of the surfactant II in the solution is 0.01% to 1%, preferably 0.1% to 0.5%, for example: 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%, etc., but is not limited thereto.
, the surfactant II is selected from benzene sulfonamide compound, polyoxyethylene diamine, octadecyl dimethyl tertiary amine, of span, or the combination of at least two of them.
preferably, the benzene sulfonamide compound is N-hydroxyethyl-N-methyl-4-perfluoroalkyleneoxy benzene sulfonamide, which has the structure shown in formula I:
step , the span is selected from span 20, span 40, span 60, span 80, or a combination of at least two thereof.
Further , the mass of the surfactant II is 0.1-10%, more preferably 0.2-5%, even more preferably 0.5-2%, such as 0.5%, 0.8%, 1%, 1.2%, 1.4%, 1.6% or 2%, etc., but not limited thereto.
And , stirring and dissolving at the temperature of 20-120 ℃ in the step S1 at the stirring speed of 200-800r/min for 0-2 h.
, the precipitant is selected from ammonia water, ammonium carbonate, and urea or at least two of them, and the water solution of the precipitant contains 1-50% by mass, preferably 3-35% by mass.
And , adding the aqueous solution of the precipitator by spray feeding, wherein the agglomeration phenomenon of the prepared powder is serious when the spray feeding time is less than 1min, and the working time is prolonged instead of positive action on the reaction when the spray feeding time is more than 60min, so that the spray feeding time is controlled to be 1-60 min.
More preferably, the spraying feeding time is controlled to be 10-60 min, such as: 10min, 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min, or 60min, and the like, but is not limited thereto.
, the aging condition is that the aging temperature is 60-100 ℃, the aging time is 8-24h, and the rotating speed is 200 and 800 r/min.
Non-limiting examples of the aging temperature include: 60 deg.C, 65 deg.C, 70 deg.C, 75 deg.C, 80 deg.C, 85 deg.C, 90 deg.C, 95 deg.C or 100 deg.C, etc.
More preferably, the aging time is from 10 to 24 hours, particularly preferably from 15 to 24 hours, for example: 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h or 24h, etc.
More preferably, the rotation speed is 500-: 500r/min, 550r/min, 600r/min, 650r/min, 700r/min, 750r/min, or 800r/min, and so forth.
In the preparation method, the drying process comprises two stages, wherein the th stage is vacuum drying at 25-50 ℃ for 8-12 h, and the second stage is vacuum drying at 100-120 ℃ for 2-4 h.
After drying, entering a roasting procedure, wherein the roasting temperature is 350-550 ℃, for example: 350 deg.C, 400 deg.C, 450 deg.C, 500 deg.C or 550 deg.C, etc. The roasting time is 3-8 h, preferably 5-8 h, for example: 5h, 5.5h, 6h, 6.5h, 7h, 7.5h or 8h, etc.
The specific area of the gamma-alumina powder prepared by the preparation method provided by the invention is up to 245-320 m2The pore diameter is 10-15 nm. The catalyst is used as a carrier to prepare a hydrogen peroxide catalyst, and has excellent effect when being used for synthesizing hydrogen peroxide by a catalytic anthraquinone method.
Definition of terms
The "water" used in the embodiments of the present invention is deionized water.
The term "filtration" as used herein means the separation of fluids from non-fluids by a medium under the action of gravity or other external forces, including but not limited to filter paper, gauze, filter elements, semi-permeable membranes, screens, etc., and in theory, materials containing porous structures may be the media of filtration; filtration devices include, but are not limited to, vacuum or pressure reduction devices, pressurization devices, centrifugation devices, and the like.
All ranges cited herein are inclusive, unless expressly stated to the contrary. For example, the aging temperature is 60-100 ℃, which means that the temperature during aging ranges from 60 ℃ to T100 ℃.
This description is to be understood as including or at least , and the singular also includes the plural unless it is obvious that it is meant otherwise.
Whenever numbers with values of N are disclosed, any number with values of N +/-1%, N +/-2%, N +/-3%, N +/-5%, N +/-7%, N +/-8% or N +/-10% is explicitly disclosed, wherein "+/-" means plus or minus and ranges between N-10% and N + 10% are also disclosed.
All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety, unless a specific section is cited, to the extent that this specification and its included definitions control, unless a conflict arises, the materials, methods, and examples are illustrative only and not intended to be limiting.
The invention has the beneficial effects that:
1) the method prepares the alumina by an acid-base precipitation method, and simultaneously introduces the surfactant I, thereby preparing the mesoporous nanocrystalline gamma-alumina powder, wherein the surfactant I can play a role in pore forming or pore canal maintaining in the drying and roasting process.
2) The invention uses the solution containing the surfactant II in the washing process, the surfactant is dissolved in the organic solvent but not dissolved in the water, the excess water of the filter cake can be effectively replaced in the washing process, and the agglomeration phenomenon is effectively reduced by reducing the water content of the filter cake, so the specific surface area is effectively improved, and the original aperture is kept not reduced.
3) The alumina powder prepared by the method is mesoporous nano gamma crystal alumina, and the specific surface area of the alumina powder is more than or equal to 250m2(ii)/g, pore diameter > 10 nm.
4) When the hydrogen peroxide catalyst obtained by molding and loading the mesoporous nanocrystalline gamma-alumina powder prepared by the invention is applied to the reaction of synthesizing hydrogen peroxide by an anthraquinone method, the catalyst shows high activity and high stability, and the hydrogenation efficiency of the catalyst is still kept at about 12% after the catalyst continuously reacts for 720 hours.
Drawings
FIG. 1: Gamma-Al prepared in examples 1 to 5, comparative example 1 and comparative example 22O3N of powder2Adsorption and desorption curve graphs;
FIG. 2: from comparative example 1, comparative example2 gamma-Al prepared in example 32O3Life diagram of catalyst prepared by using powder as carrier.
Detailed Description
It should be noted that those skilled in the art, upon attaining an understanding of the present invention, may readily produce alterations to, variations of, and equivalents to these embodiments and modifications, and further illustrate the invention by way of example only and not by way of limitation, further .
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