Alumina powder and method for producing the same

Abstract

The application relates to an alumina powder and a preparation method thereof, and the method comprises the following steps: stirring pseudo-boehmite, an acid solution and an ammonium salt to obtain an alumina sol; wherein the pseudo-boehmite has set crystallization parameters; aging the alumina sol, and then drying and crushing the alumina sol to obtain the alumina powder. The application selects the pseudo-boehmite with the set crystallization parameters as a main raw material to realize the characteristics of good peptization, fast peptization rate, high peptization rate and low peptization viscosity of the pseudo-boehmite, hydrogen ions in the acid solution are used to break the oxygen bridge bonds in the pseudo-boehmite to generate a sol body with alumina hydrate (Al2O3.xH2O) as a gel nucleus, and the ammonium salt is used to reduce the sol viscosity, increase the alumina content in the slurry, and then obtain the alumina powder through aging, drying and crushing. The powder can be dissolved in water to obtain a transparent or translucent sol, so that the technical problem of poor water solubility of the existing alumina product is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of synthetic preparation of alumina compounds, and particularly relates to an alumina powder and a preparation method thereof. BACKGROUND

[0002] At present, the pseudo-boehmite product produced by the CO2 gas carbonation decomposition method and the neutralization method can be used to prepare the pseudo-boehmite by taking the sodium aluminate solution refined by desilication after the bauxite dissolution as the raw material. The pseudo-boehmite products obtained by controlling different conditions have great performance differences.

[0003] However, the performance of the pseudo-boehmite affects the alumina sol obtained finally, the alumina content of the alumina sol is low (<30%), the volume is large and the alumina sol is in a liquid state, and the transportation requirements and cost are high. SUMMARY

[0004] The present application provides an alumina powder and a preparation method thereof, so as to solve the technical problem of poor water solubility of the existing alumina product.

[0005] In a first aspect, the present application provides a preparation method of an alumina powder, and the method comprises the following steps:

[0006] stirring the pseudo-boehmite, an acid solution and an ammonium salt to obtain an alumina sol, wherein the pseudo-boehmite has a set crystallization parameter;

[0007] aging the alumina sol, and then drying and crushing the alumina sol to obtain the alumina powder.

[0008] Optionally, the set crystallization parameter comprises: a crystallinity of 75% to 85%, a grain size of 0.1 to 0.5 microns, and a specific surface area of 100 to 200 m2 / g.

[0009] Optionally, the ammonium salt comprises one of the following: urea, ammonium bicarbonate and ammonium carbonate.

[0010] Optionally, the acid solution is an inorganic acid or an organic acid.

[0011] Optionally, the inorganic acid comprises one of the following: hydrochloric acid, nitric acid and sulfuric acid, and / or the organic acid comprises one of the following: formic acid and acetic acid.

[0012] Optionally, the temperature of the stirring is 10 to 60 degrees Celsius.

[0013] Optionally, the weight content of the alumina in the alumina sol is 1% to 40%.

[0014] Optionally, the adding flow of the acid solution is 0.01 to 100 ml / min.

[0015] Optionally, the ammonium salt is 1-200 parts by weight relative to 1 part by weight of alumina in the alumina sol.

[0016] In a second aspect, the application provides an alumina powder, which is prepared by the method of any one of the first aspect.

[0017] The above technical solution provided by the embodiments of the application has the following advantages compared with the prior art:

[0018] The preparation method of the alumina powder provided by the embodiments of the application selects pseudo-boehmite with a set crystallization parameter as a main raw material, so as to realize the characteristics of good peptization, fast peptization rate, high peptization rate and low peptization viscosity of the pseudo-boehmite, and hydrogen ions in the acid solution are used to break the oxygen bridge bond in the pseudo-boehmite to generate a sol with alumina hydrate (Al2O3·xH2O) as a gel nucleus, and the ammonium salt is used to reduce the sol viscosity and increase the alumina content in the slurry, and then the alumina powder is obtained through aging, drying and crushing. The powder can be dissolved in water to obtain a transparent or translucent sol, which solves the technical problem of poor water solubility of the existing alumina product, thereby increasing the convenience of storage and transportation of the alumina sol. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one embodiment consistent with the application and, together with the description, serve to explain the principles of the application.

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings without creative labor.

[0021] Figure 1 A flowchart of a preparation method of an alumina powder provided by the embodiments of the application is shown in the figure.

[0022] Figure 2 A preparation diagram of an alumina sol provided by the embodiments of the application is shown in the figure.

[0023] Figure 3 A mutual conversion diagram of an alumina sol and an alumina powder provided by the embodiments of the application is shown in the figure.

[0024] Figure 4 An appearance diagram of an alumina sol provided by the embodiments of the application is shown in the figure. DETAILED DESCRIPTION

[0025] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0026] Various embodiments of the present application can exist in the form of a range; it should be understood that the description in the form of a range is merely for the convenience and brevity, and should not be understood as a hard limit on the scope of the present application; therefore, it should be considered that the described range has been specifically disclosed all possible sub-ranges and single values in the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers in the range, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated in the present application, it refers to any cited number (fraction or integer) in the indicated range.

[0027] In the present application, the orientation words such as "upper" and "lower" are specific to the drawing direction in the drawings. In addition, in the description of the specification of the present application, the terms "include", "contain" and the like mean "include but not limited to". In the present text, the relationship terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. In the present text, "and / or" describes the relationship between the associated objects, which means that there can be three relationships, for example, A and / or B can represent the cases of A alone, A and B together, and B alone. Wherein A, B can be singular or plural. In the present text, "one or more" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of the items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can represent a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, c can be single or multiple.

[0028] Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0029] In a first aspect, the present application provides a preparation method of alumina powder, which comprises Figure 1 , and the method comprises:

[0030] S1, stirring pseudo-boehmite, acid solution and ammonium salt to obtain alumina sol; wherein the pseudo-boehmite has a set crystallization parameter;

[0031] The pseudo-boehmite with the set crystallization parameter is selected as the main raw material to realize the characteristics of good peptization, fast peptization rate, high peptization rate and low peptization viscosity of the pseudo-boehmite, and the hydrogen ions in the acid solution are used to break the oxygen bridge bonds in the pseudo-boehmite to generate sol with alumina hydrate (Al2O3·xH2O) as the gel nucleus, and the ammonium salt is used to reduce the sol viscosity and increase the alumina content in the slurry.

[0032] Specifically, referring to Figure 2 , the S1 step comprises: slurry preparation process: first add a certain amount of base solution in the slurry tank, and add a certain amount of pseudo-boehmite under stirring; gelation process: slowly add acid solution to the slurry, and add ammonium salt at the same time to obtain alumina sol. Generally, the above base solution is used to better disperse the reaction raw materials, and the base solution can be distilled water or deionized water.

[0033] In some embodiments, the set crystallization parameter comprises: crystallinity of 75% to 85%, and grain size of 0.5 to 1.5 microns.

[0034] In the embodiments of the present application, the crystallinity and grain size of the pseudo-boehmite are set to ensure that the product has good peptization performance and can generate transparent sol. If the crystallinity is too high, it will increase the difficulty of production to some extent, and the generated sol is white and not transparent; if the crystallinity is too low, it will increase the content of impurity crystals or amorphous crystals to some extent, which will reduce the peptization performance, cause precipitation and affect the clarity of the peptization solution. If the grain size is too high, it will reduce the peptization rate to some extent and prolong the peptization reaction time; if the grain size is too low, it will not be able to generate transparent sol due to imperfect crystal development. Specifically, the crystallinity of the pseudo-boehmite can be 75%, 77%, 79%, 81%, 83%, 85%, etc., and the grain size of the pseudo-boehmite can be 0.5 microns, 0.6 microns, 0.7 microns, 0.8 microns, 0.9 microns, 1.0 microns, 1.1 microns, 1.2 microns, 1.3 microns, 1.4 microns, 1.5 microns, etc. In addition, the pseudo-boehmite can be obtained by sodium bicarbonate or ammonium bicarbonate neutralization method.

[0035] In some embodiments, the ammonium salt comprises one of the following: urea, ammonium bicarbonate, ammonium carbonate.

[0036] ​In the embodiment of the present application, the ammonium salt is selected as the additive to reduce the viscosity of the sol and increase the concentration of alumina in the sol. One of urea, ammonium bicarbonate and ammonium carbonate is selected as the ammonium salt, which can preferably achieve the purposes of reducing the viscosity of the sol and increasing the concentration of alumina in the sol. Preferably, the ammonium salt can be urea.

[0037] In some embodiments, the acid solution is an inorganic acid or an organic acid.

[0038] In some embodiments, the inorganic acid includes one of hydrochloric acid, nitric acid and sulfuric acid, and / or the organic acid includes one of formic acid and acetic acid.

[0039] In the embodiment of the present application, the hydrogen ions in the inorganic acid or the organic acid break the oxygen bridge bonds in the pseudo-boehmite to generate a sol with alumina hydrate (Al2O3·xH2O) as the core. One of hydrochloric acid, nitric acid and sulfuric acid is selected as the acid solution in the inorganic acid, which can produce a transparent alumina sol with high solid content. Preferably, nitric acid is selected. Formic acid and acetic acid are selected as the acid solution in the organic acid, which can also reduce environmental pollution. Preferably, formic acid is selected. The mass fraction of the acid solution is 1% to 98%, and preferably 60% to 68%.

[0040] In some embodiments, the temperature of the stirring is 10°C to 60°C.

[0041] In the embodiment of the present application, the stirring temperature for obtaining the alumina sol is controlled to obtain a suitable solubilization effect. If the temperature of the stirring is too high, the reaction will be too violent to some extent, and the added ammonium salt will be ineffective due to decomposition at high temperature. If the temperature of the stirring is too low, the solubilization will be difficult to some extent, the solubilization time will be too long, and even the solubilization will be impossible. Specifically, the temperature of the stirring can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, etc.

[0042] In some embodiments, the weight content of alumina in the alumina sol is 1% to 40%.

[0043] In the embodiment of the present application, the weight content of alumina in the alumina sol is controlled by controlling the amount of the pseudo-boehmite added, so that the weight content of alumina in the alumina sol is 1% to 40%. The high content of alumina can reduce the energy consumption in subsequent processes, and a too high content of alumina can result in a non-transparent sol. Specifically, the weight content of alumina in the alumina sol can be 1%, 3%, 5%, 7%, 9%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, etc. Preferably, the weight content of alumina in the alumina sol can be 20% to 40%.

[0044] In some embodiments, the flow rate of the acid solution is 0.01 ml / min to 100 ml / min.

[0045] In the embodiments of the present application, the flow rate of the acid solution is controlled to maximize the effect of the acid dissolution reaction. If the flow rate of the acid solution is too high, the added acid will not react with the pseudo-boehmite in time, resulting in an excessive amount of acid. If the flow rate of the acid solution is too low, the reaction time will be too long and the efficiency will be low. Specifically, the flow rate of the acid solution can be 0.01 ml / min, 0.1 ml / min, 1 ml / min, 10 ml / min, 50 ml / min, 100 ml / min, etc. Preferably, the flow rate of the acid solution can be 0.1 ml / min to 2.0 ml / min.

[0046] In some embodiments, the amount of the ammonium salt is 1 part by weight to 200 parts by weight relative to 1 part by weight of the alumina in the alumina sol.

[0047] In the embodiments of the present application, the amount of the ammonium salt is controlled to achieve the purposes of reducing the viscosity of the sol and increasing the concentration of alumina in the sol. If the amount of the ammonium salt is too large, the cost will be increased and waste will be caused. If the amount of the ammonium salt is too small, the dispersion effect will not be achieved, the peptization effect will be affected, and the content of alumina in the sol will be reduced. Specifically, the amount of the ammonium salt can be 1 part by weight, 3 parts by weight, 5 parts by weight, 7 parts by weight, 9 parts by weight, 10 parts by weight, 20 parts by weight, 30 parts by weight, 40 parts by weight, 50 parts by weight, 100 parts by weight, 150 parts by weight, 200 parts by weight, etc. relative to 1 part by weight of the alumina in the alumina sol. Preferably, the amount of the ammonium salt can be 50 parts by weight to 100 parts by weight relative to 1 part by weight of the alumina in the alumina sol.

[0048] S2, aging the alumina sol, and then drying and crushing the alumina sol to obtain an alumina powder.

[0049] In the embodiments of the present application, the aging time is 0.1 h to 5 h, and is preferably 30 min to 60 min. The slurry is then dried and crushed by a drying device to obtain a white alumina powder. The alumina sol is aged, dried, and crushed to obtain an alumina powder, which can be dissolved in water to obtain a transparent or translucent sol, thereby solving the technical problem of poor water solubility of existing alumina products and increasing the convenience of storage and transportation of the alumina sol. The alumina powder is suitable for use as a binder in the petroleum catalytic cracking industry, is also a good coating and impregnation alumina, and can also be used as a coating for high-grade paper.

[0050] In a second aspect, the present application provides an alumina powder prepared by the method of any one of the first aspect.

[0051] The alumina powder is prepared based on the above-mentioned method for preparing alumina powder. The specific steps of the method for preparing alumina powder can refer to the above-mentioned examples. Since the alumina powder adopts part or all of the technical solutions of the above-mentioned examples, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned examples, which will not be described one by one here.

[0052] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods not specified in the following examples are generally determined according to the national standards. If there is no corresponding national standard, the general international standard, the conventional condition, or the condition suggested by the manufacturer is used.

[0053] The present application provides a method for preparing alumina powder, which comprises:

[0054] S11, stirring pseudo-boehmite, an acid solution and an ammonium salt to obtain an alumina sol; wherein the pseudo-boehmite has a set crystallization parameter;

[0055] S21, aging the alumina sol, and then drying and crushing to obtain an alumina powder. The specific process steps can refer to Examples 1-3.

[0056] Example 1

[0057] Pseudo-boehmite prepared by sodium bicarbonate neutralization method 30g, crystallinity 82%, crystal size Slowly add to 30ml water and stir evenly, keep the slurry temperature at 30℃, add 68% nitric acid solution with a peristaltic pump, the flow rate of the nitric acid solution is 0.01ml / min, while adding urea 15g, a total of 6.58ml of nitric acid solution, so that the pseudo-boehmite slurry becomes a translucent sol, keep stirring the sol at 30℃ for 30 minutes, then age for 30 minutes to obtain a transparent sol with an alumina content of 25%. Pour the sol into a porcelain dish and dry in an oven at 120℃ to obtain a translucent solid, which is crushed by a crusher to obtain an alumina powder.

[0058] Example 2

[0059] Pseudo-boehmite prepared by sodium bicarbonate neutralization method 10g, crystallinity 85%, crystal size The pseudo-boehmite slurry was slowly added into 30 ml water and stirred, the slurry temperature was kept at 30°C, 68% nitric acid solution was added by peristaltic pump, the flow rate of the nitric acid solution was 0.01 ml / min, 1 g urea was added at the same time, 6.58 ml nitric acid solution was added in total, the pseudo-boehmite slurry became a paste-like slurry, the slurry was stirred at 30°C for 30 minutes, then aged for 30 minutes, a white paste-like paste with an alumina content of 25% was obtained. The paste was poured into a porcelain dish and dried in an oven at 120°C to obtain a white solid, which was crushed by a crusher to obtain the final alumina powder.

[0060] Example 3

[0061] Pseudo-boehmite prepared by sodium bicarbonate neutralization method, 50 g, crystallinity 78%, crystal size 100 nm, was selected. The pseudo-boehmite slurry was slowly added into 30 ml water and stirred, the slurry temperature was kept at 30°C, 68% nitric acid solution was added by peristaltic pump, the flow rate of the nitric acid solution was 0.01 ml / min, 1 g urea was added at the same time, 6.58 ml nitric acid solution was added in total, the pseudo-boehmite slurry became a paste-like slurry, the slurry was stirred at 30°C for 30 minutes, then aged for 30 minutes, a white paste-like paste with an alumina content of 25% was obtained. The paste was poured into a porcelain dish and dried in an oven at 120°C to obtain a white solid, which was crushed by a crusher to obtain the final alumina powder.

[0062] Comparative Example 1

[0063] Pseudo-boehmite prepared by sodium bicarbonate neutralization method, 30 g, crystallinity 70%, crystal size 100 nm, was selected. The pseudo-boehmite slurry was slowly added into 30 ml water and stirred, the slurry temperature was kept at 30°C, 68% nitric acid solution was added by peristaltic pump, the flow rate of the nitric acid solution was 0.01 ml / min, 1 g urea was added at the same time, 6.58 ml nitric acid solution was added in total, the pseudo-boehmite slurry became a paste-like slurry, the slurry was stirred at 30°C for 30 minutes, then aged for 30 minutes, a white paste-like paste with an alumina content of 25% was obtained. The paste was poured into a porcelain dish and dried in an oven at 120°C to obtain a white solid, which was crushed by a crusher to obtain the final alumina powder.

[0064] The water solubility of the alumina powder prepared in Examples 1-3 and Comparative Example 1 was evaluated, and the results are shown in Table 1.

[0065] Table 1 Water solubility evaluation results of alumina powder

[0066]

[0067] Through the analysis of Table 1, the alumina powder prepared by the preparation method of the alumina powder of the present application examples 1-3 can be dissolved in water to form a translucent sol or sol, which protects the original performance of the alumina sol. In order to facilitate storage and transportation, it can be stored and transported in solid powder form, which reduces the storage and transportation cost of the alumina sol. For details, please see Figure 3 The alumina sol provided by the present application example is shown in the schematic diagram of the mutual transformation of the alumina sol and the alumina powder; and Figure 4 The appearance of the alumina sol provided by the present application example is shown in the schematic diagram; wherein the left graph is a transparent sol, and the right graph is a translucent sol. In the comparative example 1, boehmite is not used in the present application example, and a white opaque paste is obtained, which does not form a sol.

[0068] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A method for preparing alumina powder, characterized in that: The method comprises: Stirring pseudo-boehmite, an acid solution, and an ammonium salt to obtain an alumina sol; wherein the pseudo-boehmite has set crystallization parameters; Aging the alumina sol, and then drying and crushing it to obtain alumina powder; The alumina powder can be dissolved in water to obtain a transparent or translucent sol; The crystallization parameters include: crystallinity of 75% to 85%, grain size of The ammonium salt includes one of the following: ammonium bicarbonate, ammonium carbonate; The stirring temperature is 10°C to 60°C; The addition rate of the acid solution is 0.01 mL / min to 100 mL / min; The aging time is 30min to 60min; The ammonium salt is present in an amount of 50 to 100 parts by weight relative to 1 part by weight of the aluminum oxide in the alumina sol; The weight content of aluminum oxide in the aluminum oxide sol is 20% to 40%.

2. The method according to claim 1, characterized in that The acid solution is an inorganic acid or an organic acid.

3. The method according to claim 2, characterized in that The inorganic acid includes one of the following: hydrochloric acid, nitric acid, sulfuric acid, and / or the organic acid includes one of the following: formic acid, acetic acid.

4. An alumina powder, characterized in that: The alumina powder is prepared by the method according to any one of claims 1 to 3.

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