A method for preparing high peptization index macroporous aluminum hydroxide powder

Abstract

The present application relates to the technical field of aluminum hydroxide preparation, and specifically discloses a method for preparing a macroporous aluminum hydroxide powder with a high peptization index. A method for preparing a macroporous aluminum hydroxide powder with a high peptization index comprises the following steps: (1) preparing a gelling mother solution a; (2) preparing a gelling mother solution b; (3) preparing a gelling mother solution c; and (4) aging. The macroporous aluminum hydroxide powder with a high peptization index prepared in the present application has the advantages of large pore volume, low bulk density, and high peptization index.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum hydroxide preparation, and more specifically, to a method for preparing macroporous aluminum hydroxide powder with a high peptization index. Background Art

[0002] At present, crude oil will produce residual oil after processing. Residual oil can be further processed through hydroprocessing technology to achieve effective utilization. Residual oil hydroprocessing technology mainly includes fixed bed residual oil hydroprocessing technology, suspended bed residual oil hydroprocessing technology and boiling bed residual oil hydroprocessing technology. Among these technologies, boiling bed residual oil hydroprocessing technology has been widely used in the field of residual oil hydroprocessing technology because of its wide adaptability to residual oil, uniform temperature in the reactor, long operation cycle, good mass transfer and heat transfer performance, and high residual oil conversion rate.

[0003] In the ebullating bed residue oil hydroprocessing technology, the catalyst carrier used is crucial to the hydroprocessing technology. Usually, alumina is selected as the catalyst carrier because alumina has a larger pore volume, pore size and specific surface area, and can load more active components. Alumina can be prepared by calcining aluminum hydroxide powder, which requires aluminum hydroxide powder to have the characteristics of large pore volume, high specific surface area, low bulk density and high peptization index. At present, in the process technology for producing aluminum hydroxide powder, the peptization index and pore volume are inversely proportional. The higher the pore volume, the lower the peptization index, and vice versa. Therefore, while maintaining the designed capacity of the device, it is impossible to simultaneously produce the index requirements of the above-mentioned powder.

[0004] The Chinese patent application document with publication number CN116143153A discloses a pseudo-boehmite with high crystallinity, large grains and large pore volume and its preparation method. The preparation method of the pseudo-boehmite with high crystallinity, large grains and large pore volume disclosed in the application document comprises: mixing aluminum salt and aluminate and performing double decomposition neutralization reaction at 90-95°C to obtain a neutralized material; performing aging treatment on the neutralized material to obtain pseudo-boehmite; performing double decomposition neutralization reaction with two reaction active centers of acid and alkali on aluminum salt and aluminate in a high temperature system, and then performing aging treatment. The pseudo-boehmite obtained by the method has the characteristics of good fluidity, large pore volume, large specific surface area, large grain size, high crystallinity, low impurity content, etc.

[0005] The specific surface area of ​​the pseudo-boehmite prepared in the above application document is slightly increased, and the presence of impurities makes the peptization solubility of the pseudo-boehmite worse. Summary of the invention

[0006] In order to further increase the pore volume and peptization index of aluminum hydroxide powder and reduce the bulk density, the present application provides a method for preparing macroporous aluminum hydroxide powder with a high peptization index.

[0007] The present application provides a method for preparing macroporous aluminum hydroxide powder with a high peptization index, which adopts the following technical scheme:

[0008] A method for preparing macroporous aluminum hydroxide powder with a high peptization index comprises the following steps:

[0009] (1) The method for preparing the gelling mother solution a comprises the following steps:

[0010] (i) injecting an aqueous solution of aluminum sulfate and an aqueous solution of sodium metaaluminate into a reaction kettle simultaneously to carry out a neutralization precipitation reaction;

[0011] (ii) after the reaction in step (i) is completed, adding acidic aluminum sol to the reaction system in step (i) to allow the reaction system to undergo a neutralization precipitation reaction in an acidic environment;

[0012] (iii) after the reaction in step (ii) is completed, adding a sodium carbonate aqueous solution to the reaction system in step (ii) to allow the reaction system to undergo a neutralization precipitation reaction in an alkaline environment to obtain a gel mother solution a;

[0013] (2) Preparation of gelling mother solution b: injecting aluminum sulfate aqueous solution and sodium metaaluminate aqueous solution into a reaction kettle at the same time to carry out neutralization precipitation reaction to obtain gelling mother solution b;

[0014] (3) Preparation of gelling mother solution c: Aqueous aluminum sulfate solution and aqueous sodium aluminate solution were simultaneously injected into a reaction kettle to carry out a neutralization precipitation reaction. Ammonium oxalate was added 10 minutes after the reaction started. After the reaction was completed, the temperature was raised to 150°C and stirred for 10 minutes to obtain gelling mother solution c.

[0015] (4) Aging: The gelling mother solution a, gelling mother solution b and gelling mother solution c in step (1), step (2) and step (3) are mixed evenly, and then activated alumina powder is added and mixed evenly, and the mixture is aged. The solid product is separated by centrifugation, washed, dried and crushed to obtain a macroporous aluminum hydroxide powder with a high peptization index.

[0016] By adopting the above technical scheme, in step (1), acidic aluminum sol and sodium carbonate aqueous solution are added to change the reaction environment from alkaline to acidic and then to alkaline, and the aluminum hydroxide product undergoes a generation, dissolution and regeneration process, during which the aluminum hydroxide grains continue to grow larger to obtain larger aluminum hydroxide grains; in step (3), oxalate is adsorbed on the aluminum hydroxide grain interface to prevent the growth of the grains, thereby obtaining smaller aluminum hydroxide grains; the comparison of the aluminum hydroxide grain sizes in step (1), step (2) and step (3) is as follows: step (1) is larger than step (2) and larger than step (3), the three sizes of grains are mixed and aged, and the obtained aluminum hydroxide powder has a higher pore volume, a lower bulk density and a higher peptization index.

[0017] Preferably, in step (i), the process parameters of the neutralization precipitation reaction are: pH value 8-10, temperature 90-110° C., and reaction time 4-6 min.

[0018] By adopting the above technical solution, aluminum ions can fully participate in the reaction in the initial stage of the reaction and reduce the formation of impurities, thereby improving the yield and purity of aluminum hydroxide.

[0019] Preferably, in step (ii), the process parameters of the neutralization precipitation reaction are: pH value 3-4.5, temperature 110-140° C., and reaction time 10-15 min.

[0020] By adopting the above technical scheme, aluminum hydroxide is continuously dissolved and generated, thereby improving the crystallinity and structural integrity of aluminum hydroxide. In addition, the particle size of aluminum hydroxide crystals is continuously increased in the process, thereby increasing the pore volume of aluminum hydroxide and reducing the bulk density of aluminum hydroxide.

[0021] Preferably, in step (iii), the process parameters of the neutralization precipitation reaction are: pH value 9-11, temperature 70-90° C., and reaction time 10-15 min.

[0022] By adopting the above technical solution, in the later stage of the reaction, the further growth of aluminum hydroxide grains is promoted, and the aluminum hydroxide structure is made more stable, preventing its structural collapse or deformation during the subsequent treatment process. In addition, the number of hydroxyl groups on the surface of aluminum hydroxide is increased, the surface activity of aluminum hydroxide is improved, and it has a higher peptization index.

[0023] Preferably, in step (iii), the mass concentration of the sodium carbonate aqueous solution is 19-21 g / 100 mL.

[0024] By adopting the above technical scheme, the growth process of aluminum hydroxide grains is controlled to be relatively stable, aluminum hydroxide has sufficient growth time and suitable growth conditions, the lattice defects of aluminum hydroxide are reduced, the structural integrity and crystallinity of aluminum hydroxide are improved, and the dissolution of aluminum hydroxide has a good peptization index.

[0025] Preferably, in the steps (1), (2) and (3), the mass concentration of the aqueous aluminum sulfate solution is 4.0-4.2 g / 100 mL, and the caustic ratio of sodium aluminate is 1.25-1.3.

[0026] By adopting the above technical scheme, the aluminum hydroxide yield is improved while ensuring the regular structure and high purity of the aluminum hydroxide, improving the stability and uniformity of the pore structure of the aluminum hydroxide, so that the aluminum hydroxide has higher peptization solubility and stability.

[0027] Preferably, in step (2) and step (3), the process parameters of the neutralization precipitation reaction are: pH value 8.5-9.5, temperature 65-75° C., and reaction time 25-30 min.

[0028] By adopting the above technical scheme, the formation of aluminum hydroxide grains is promoted, the formation of impurities is reduced, and the peptization index of aluminum hydroxide is improved; at the same time, the aluminum hydroxide is endowed with a rich pore structure and a larger pore volume, thereby reducing the bulk density of aluminum hydroxide.

[0029] Preferably, in step (3), the mass ratio of ammonium oxalate to aluminum sulfate aqueous solution is 1:(45-50).

[0030] By adopting the above technical solution, the growth of aluminum hydroxide is restricted, thereby obtaining relatively fine grains, which can effectively reduce the grain size of aluminum hydroxide, make aluminum hydroxide have more porous structures, and increase the specific surface area of ​​aluminum hydroxide.

[0031] Preferably, in step (4), the mass ratio of gelling solution a, gelling solution b, gelling solution c and activated alumina powder is (4-6):(2.5-4):(3-4):1.

[0032] By adopting the above technical scheme, the prepared aluminum hydroxide particles have a rich pore structure, a large pore volume and specific surface area, and the aluminum hydroxide has few internal defects and good structural stability; the addition of an appropriate amount of activated alumina powder increases the generation rate of aluminum hydroxide, guides the regular growth of aluminum hydroxide crystals, and improves the crystallinity of aluminum hydroxide.

[0033] Preferably, in step (4), the aging temperature is 80-90° C. and the aging time is 2-3 h.

[0034] By adopting the above technical scheme, aluminum hydroxide crystals can grow rapidly and orderly, and the growth rate of aluminum hydroxide crystals is stable, reducing the possibility of defects inside the aluminum hydroxide crystals; it also makes the aluminum hydroxide crystals have good crystallinity, making the structure of the aluminum hydroxide crystals complete and stable.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. During the reaction process, by regulating the change of pH, the amorphous precipitate is dissolved in an acidic environment and crystallized on aluminum hydroxide in an alkaline environment, thereby reducing the formation of impurity crystals and improving the crystallinity and purity of the product. As the number of pH changes increases, the volume of the grains continues to increase, and larger aluminum hydroxide grains are obtained, thereby reducing the bulk density of aluminum hydroxide powder.

[0037] 2. Oxalate ions are adsorbed on the surface of aluminum hydroxide powder crystals and produce hydrogen bonds with hydroxyl groups, which prevents the continued growth of the crystal surface and reduces the grain volume.

[0038] 3. Add activated alumina powder seeds during the aging process to induce the formation of high peptization index particles, thereby increasing the yield and qualified rate of finished products.

[0039] 4. The mixture of three different sized grains can form pores of different sizes. The formed crystals have a higher specific surface area while maintaining a larger pore size and pore volume. When the product is dried or roasted, it will lose water and cause volume shrinkage, generating internal stress. The mixture of grains of different sizes increases the contact area between grains, allowing the stress to be better dispersed, avoiding cracks caused by stress concentration, and enhancing its stability. DETAILED DESCRIPTION

[0040] The present application is further described in detail below with reference to the embodiments.

[0041] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0042] The activated alumina powder used in this embodiment and the comparative example is the activated alumina powder prepared in Example 1 in the Chinese patent document with publication number CN112794350B.

[0043] Example 1

[0044] The preparation method of the high peptization index macroporous aluminum hydroxide powder of this embodiment comprises the following steps:

[0045] (1) The preparation method of the gelling mother solution a is as follows:

[0046] (i) 90 g of an aqueous solution of aluminum sulfate having a mass concentration of 4.0 g / 100 mL and 180 g of an aqueous solution of sodium metaaluminate having a caustic ratio of 1.25 were simultaneously injected into a reaction kettle, and a neutralization precipitation reaction was carried out at a pH of 8 and a temperature of 90° C. The reaction time was 4 min;

[0047] (ii) After the reaction in step (i) is completed, acidic aluminum sol VK-JR14W is added to the reaction system in step (i) to adjust the pH value to 3, the reaction temperature to 110°C, and the reaction time to 10 min;

[0048] (iii) After the reaction in step (ii) is completed, a sodium carbonate aqueous solution with a mass concentration of 19 g / 100 mL is added to the reaction system in step (ii) to adjust the pH value to 9, the reaction temperature to 70° C., and the reaction time to 10 min to obtain a gel mother solution a;

[0049] (2) Preparation of gelling mother solution b: 90 g of an aqueous solution of aluminum sulfate with a mass concentration of 4.0 g / 100 mL and 180 g of an aqueous solution of sodium metaaluminate with a caustic ratio of 1.25 were simultaneously injected into a reaction kettle, and a neutralization precipitation reaction was carried out at a pH of 8.5 and a temperature of 65°C for 25 min to obtain a gelling mother solution b;

[0050] (3) Preparation of gelling mother solution c: 90 g of an aqueous solution of aluminum sulfate with a mass concentration of 4.0 g / 100 mL and 180 g of an aqueous solution of sodium metaaluminate with a caustic ratio of 1.25 were simultaneously injected into a reactor, and a neutralization precipitation reaction was carried out at a pH of 8.5 and a temperature of 65°C. The reaction time was 25 min, and 2 g of ammonium oxalate was added 10 min after the reaction started. After the reaction was completed, the temperature was raised to 150°C and stirred for 10 min to obtain a gelling mother solution c.

[0051] (4) Aging: Mix 40g of gelling solution a, 25g of gelling solution b and 30g of gelling solution c, then add 10g of activated alumina powder and mix evenly. Age at 80°C for 2h, separate the solid product by centrifugation, wash, dry and crush to obtain macroporous aluminum hydroxide powder with high peptization index.

[0052] Example 2

[0053] The preparation method of the high peptization index macroporous aluminum hydroxide powder of this embodiment comprises the following steps:

[0054] (1) The preparation method of the gelling mother solution a is as follows:

[0055] (i) injecting 100 g of an aqueous solution of aluminum sulfate having a mass concentration of 4.2 g / 100 mL and 230 g of an aqueous solution of sodium metaaluminate having a caustic ratio of 1.3 into a reaction kettle at the same time, and carrying out a neutralization precipitation reaction at a pH value of 10 and a temperature of 110° C. for a reaction time of 6 min;

[0056] (ii) After the reaction in step (i) is completed, acidic aluminum sol SS-LA20W is added to the reaction system in step (i) to adjust the pH value to 4.5, the reaction temperature to 140°C, and the reaction time to 15 min;

[0057] (iii) After the reaction in step (ii) is completed, a sodium carbonate aqueous solution with a mass concentration of 21 g / 100 mL is added to the reaction system in step (ii) to adjust the pH value to 11, the reaction temperature to 90° C., and the reaction time to 15 min to obtain a gel mother solution a;

[0058] (2) Preparation of gelling mother solution b: 100 g of an aqueous solution of aluminum sulfate with a mass concentration of 4.2 g / 100 mL and 220 g of an aqueous solution of sodium metaaluminate with a caustic ratio of 1.3 were simultaneously injected into a reaction kettle, and a neutralization precipitation reaction was carried out at a pH of 9.5 and a temperature of 75°C for 30 min to obtain a gelling mother solution b;

[0059] (3) Preparation of gelling mother solution c: 100 g of an aqueous solution of aluminum sulfate with a mass concentration of 4.2 g / 100 mL and 220 g of an aqueous solution of sodium metaaluminate with a caustic ratio of 1.3 were simultaneously injected into a reactor, and a neutralization precipitation reaction was carried out at a pH of 9.5 and a temperature of 75°C. The reaction time was 30 min, and 2 g of ammonium oxalate was added 10 min after the reaction started. After the reaction was completed, the temperature was raised to 150°C and stirred for 10 min to obtain a gelling mother solution c.

[0060] (4) Aging: Mix 60g of gelling solution a, 40g of gelling solution b and 40g of gelling solution c, add 10g of activated alumina powder and mix evenly, age at 90°C for 3h, separate the solid product by centrifugation, wash, dry and crush to obtain high gelling index macroporous aluminum hydroxide powder.

[0061] Example 3

[0062] The preparation method of the high peptization index macroporous aluminum hydroxide powder of this embodiment comprises the following steps:

[0063] (1) The preparation method of the gelling mother solution a is as follows:

[0064] (i) 92 g of an aqueous solution of aluminum sulfate having a mass concentration of 4.1 g / 100 mL and 175 g of an aqueous solution of sodium metaaluminate having a caustic ratio of 1.27 were simultaneously injected into a reaction kettle, and a neutralization precipitation reaction was carried out at a pH of 8.5 and a temperature of 98° C. for 4 min;

[0065] (ii) After the reaction in step (i) is completed, acidic aluminum sol SS-LA25W is added to the reaction system in step (i) to adjust the pH value to 4, the reaction temperature to 120°C, and the reaction time to 12 minutes;

[0066] (iii) After the reaction in step (ii) is completed, a sodium carbonate aqueous solution with a mass concentration of 20 g / 100 mL is added to the reaction system in step (ii) to adjust the pH value to 9.5, the reaction temperature to 75° C., and the reaction time to 12 min to obtain a gel mother solution a;

[0067] (2) Preparation of gelling mother solution b: 92 g of an aqueous solution of aluminum sulfate with a mass concentration of 4.1 g / 100 mL and 180 g of an aqueous solution of sodium metaaluminate with a caustic ratio of 1.27 were simultaneously injected into a reaction kettle, and a neutralization precipitation reaction was carried out at a pH of 8.9 and a temperature of 68°C for 26 min to obtain a gelling mother solution b;

[0068] (3) Preparation of gelling mother solution c: 92 g of an aqueous solution of aluminum sulfate with a mass concentration of 4.1 g / 100 mL and 180 g of an aqueous solution of sodium metaaluminate with a caustic ratio of 1.27 were simultaneously injected into a reactor, and a neutralization precipitation reaction was carried out at a pH of 8.9 and a temperature of 68°C. The reaction time was 26 min, and 2 g of ammonium oxalate was added 10 min after the reaction started. After the reaction was completed, the temperature was raised to 150°C and stirred for 10 min to obtain a gelling mother solution c.

[0069] (4) Aging: Mix 55g of gelling solution a, 30g of gelling solution b and 35g of gelling solution c, then add 10g of activated alumina powder and mix evenly. Age at 85°C for 2.5h, separate the solid product by centrifugation, wash, dry and grind to obtain macroporous aluminum hydroxide powder with high peptization index.

[0070] Comparative Example 1

[0071] The difference between this comparative example and Example 1 is that no activated alumina powder is added during the aging process in this comparative example.

[0072] Comparative Example 2

[0073] The preparation method of the high peptization index macroporous aluminum hydroxide powder of this comparative example comprises the following steps:

[0074] 90g of aluminum sulfate aqueous solution with a mass concentration of 4.0g / 100mL and 170g of sodium aluminate aqueous solution with a caustic ratio of 1.25 were injected into the reactor at the same time, and a neutralization precipitation reaction was carried out at a pH value of 8.5 and a temperature of 65°C. The reaction time was 25min. After the reaction was completed, it was aged at a temperature of 80°C for 2h, and the solid product was separated by centrifugation, washed, and dried to obtain a high peptization index macroporous aluminum hydroxide powder.

[0075] Performance testing

[0076] The performance test method of high peptization index macroporous aluminum hydroxide powder is as follows:

[0077] 1. Pore volume, specific surface area and pore distribution test

[0078] The pore volume, specific surface area and pore distribution test method of high peptization index macroporous aluminum hydroxide powder refer to the national standard GB / T19587-2017 and are measured by the fully automatic BET specific surface and pore size analyzer model V-Sorb 4800TP produced by Beijing Guoyi Precision Measurement Technology Co., Ltd.

[0079] 2. Measurement of Peptization Index

[0080] The test method for the peptization index of high peptization index macroporous aluminum hydroxide powder refers to the industry standard YS / T1161.1-2016.

[0081] The performance test data of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 are shown in Table 1 below:

[0082]

[0083] The pore distribution test data of the powders of the embodiment and the comparative example are shown in Table 2 below:

[0084]

[0085] From the analysis of Examples 1-3, Comparative Examples 1 and 2 and in combination with Tables 1 and 2, it can be seen that the high peptization index macroporous aluminum hydroxide powder prepared in the present application has the characteristics of large pore volume, high specific surface area, low bulk density and high peptization index.

[0086] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing macroporous aluminum hydroxide powder with a high peptization index, characterized in that: The steps include: (1) The method for preparing the gelling mother solution a comprises the following steps: (i) injecting an aqueous solution of aluminum sulfate and an aqueous solution of sodium metaaluminate into a reaction container simultaneously to carry out a neutralization precipitation reaction; (ii) after the reaction in step (i) is completed, adding acidic aluminum sol to the reaction system in step (i) to allow the reaction system to undergo a neutralization precipitation reaction in an acidic environment; (iii) after the reaction in step (ii) is completed, adding a sodium carbonate aqueous solution to the reaction system in step (ii) to allow the reaction system to undergo a neutralization precipitation reaction in an alkaline environment to obtain a gel mother solution a; (2) Preparation of gelling mother solution b: injecting aluminum sulfate aqueous solution and sodium metaaluminate aqueous solution into a reaction kettle at the same time to carry out neutralization precipitation reaction to obtain gelling mother solution b; (3) Preparation of gelling mother solution C: Aluminum sulfate aqueous solution and sodium aluminate aqueous solution are injected into a reaction kettle at the same time to carry out a neutralization precipitation reaction. After the reaction starts, ammonium oxalate is added. After the reaction is completed, the temperature is increased and stirring is continued to obtain gelling mother solution C. (4) Aging: The gelling solution a, gelling solution b and gelling solution in step (1), step (2) and step (3) are mixed uniformly in a mass ratio of (4-6):(2.5-4):(3-4), and then activated alumina powder is added and mixed uniformly. The mixture is aged at a temperature of 80-90° C. for 2-3 h. The solid product is separated by centrifugation, washed, dried and crushed to obtain a macroporous aluminum hydroxide powder with a high peptization index.

2. The method for preparing a macroporous aluminum hydroxide powder with a high peptization index according to claim 1, characterized in that: In the step (i), the process parameters of the neutralization precipitation reaction are: pH value 8-10, temperature 90-110° C., and reaction time 4-6 min.

3. The method for preparing a high peptization index macroporous aluminum hydroxide powder according to claim 1, characterized in that: In the step (ii), the process parameters of the neutralization precipitation reaction are: pH value 3-4.5, temperature 110-140° C., and reaction time 10-15 min.

4. The method for preparing a macroporous aluminum hydroxide powder with a high peptization index according to claim 1, characterized in that: In the step (iii), the process parameters of the neutralization precipitation reaction are: pH value 9-11, temperature 70-90° C., and reaction time 10-15 min.

5. The method for preparing a high peptization index macroporous aluminum hydroxide powder according to claim 1, characterized in that: In the step (iii), the mass concentration of the sodium carbonate aqueous solution is 19-21 g / 100 mL.

6. The method for preparing a high peptization index macroporous aluminum hydroxide powder according to claim 1, characterized in that: In the steps (1), (2) and (3), the mass concentration of the aqueous solution of aluminum sulfate is 4.0-4.2 g / 100 mL, and the caustic ratio of sodium aluminate is 1.25-1.

3.

7. The method for preparing a macroporous aluminum hydroxide powder with a high peptization index according to claim 1, characterized in that: In the steps (2) and (3), the process parameters of the neutralization precipitation reaction are: pH value 8.5-9.5, temperature 65-75° C., and reaction time 25-30 min.

8. The method for preparing a macroporous aluminum hydroxide powder with a high peptization index according to claim 1, characterized in that: In the step (3), the mass ratio of ammonium oxalate to the aqueous solution of aluminum sulfate is 1:(45-50).

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