Pseudo-boehmite and preparation method thereof

Abstract

The invention provides pseudo-boehmite and a preparation method thereof, and the method comprises the following steps: carrying out a neutralization reaction on sodium metaaluminate and an acidic aluminum salt to generate an amorphous precipitate, so as to obtain first slurry; filtering the first slurry, and pulping a filter cake obtained by filtering to obtain second slurry; and adjusting the pH value of the second slurry to a preset pH value by using an alkaline additive so as to age the second slurry, thereby obtaining the pseudo-boehmite. The prepared pseudo-boehmite meets the following indexes: the pore volume is greater than 1.2 ml / g, and the impurity content of acidic components is lower than 0.5 wt%.

Description

Technical Field

[0001] The present application relates to the technical field of pseudo-boehmite production, and in particular to pseudo-boehmite and a preparation method thereof. Background Art

[0002] The catalyst prepared by using pseudo-boehmite as catalyst raw material has the characteristics of large pore volume and high specific surface area. The high pores can effectively provide channels for macromolecular compounds to diffuse into the interior of catalyst particles, and the high specific surface area can effectively improve the dispersion of active metals. Therefore, pseudo-boehmite is often used as a catalyst carrier and catalyst raw material to improve the reaction activity of the catalyst. With the gradual deterioration of oil products and the gradual development of the petroleum hydrogenation industry, there is an urgent demand for large-pore pseudo-boehmite.

[0003] At present, the mainstream processes for macroporous pseudo-boehmite are carbonation and double aluminum methods. Because the carbonation method is easy to produce impurities and is difficult to control, affecting the purity of pseudo-boehmite, the double aluminum method is mainly used. However, the pore volume of macroporous pseudo-boehmite produced by the double aluminum method on the market is generally between 1.0-1.2ml / g, and the acidic components in the double aluminum method will bring in impurities, which is difficult to meet the requirements for pore volume and impurities in the preparation process of special catalysts. Therefore, macroporous pseudo-boehmite with low impurities and ultra-large pore volume needs to be urgently solved. Summary of the invention

[0004] The present application provides a pseudo-boehmite and a preparation method thereof to solve the following technical problem: how to simultaneously achieve low impurities and ultra-large pore volume of pseudo-boehmite.

[0005] In a first aspect, the present application provides a method for preparing pseudo-boehmite, the method comprising:

[0006] The sodium metaaluminate and the acidic aluminum salt are subjected to a neutralization reaction to generate an amorphous precipitate to obtain a first slurry;

[0007] The first slurry is filtered, and then the filter cake obtained by filtration is beaten to obtain a second slurry;

[0008] The pH value of the second slurry is adjusted to a preset pH value using an alkaline auxiliary agent, so that the second slurry is aged to obtain pseudo-boehmite.

[0009] Optionally, the acidic aluminum salt includes at least one of the following: aluminum sulfate, aluminum chloride, and sodium acetate.

[0010] Optionally, the sodium aluminate meets the following indicators: a caustic ratio αK of 1.4 to 2.5, and an alumina content of 30 g / L to 150 g / L.

[0011] Optionally, the process parameters of the neutralization reaction include: pH value 5.5-7.0, temperature 10°C-65°C.

[0012] Optionally, the preset pH value is 7.5-10.0.

[0013] Optionally, the aging process parameters include: temperature 75°C to 100°C, time 30min to 210min.

[0014] Optionally, the alkaline auxiliary agent includes at least one of the following: Na2CO3, NaOH, NaNH2.

[0015] Optionally, the concentration of the alkaline auxiliary agent is 10 g / L to 120 g / L.

[0016] In a second aspect, the present application provides pseudo-boehmite prepared by the method described in any one of the first aspects.

[0017] Optionally, the pseudo-boehmite meets the following indicators: a pore volume greater than 1.2 ml / g, and an impurity content of the acidic component less than 0.5 wt%.

[0018] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0019] The preparation method of pseudo-boehmite provided in the embodiment of the present application includes: neutralizing sodium aluminate and acidic aluminum salt to generate an amorphous precipitate to obtain a first slurry; filtering the first slurry, and then beating the filter cake obtained by filtration to obtain a second slurry; using an alkaline auxiliary agent to adjust the pH value of the second slurry to a preset pH value, so that the second slurry is aged to obtain pseudo-boehmite. Sodium aluminate and acidic aluminum salt are neutralized to generate an amorphous precipitate, and no crystal is formed during the neutralization reaction, thereby preventing impurities from being coated inside the crystal, facilitating subsequent filtration and impurity removal, and at the same time, the reaction uniformity in the neutralization process can be achieved during the neutralization reaction; filtering and impurity removal of the precipitate produced in the neutralization reaction increases the reaction intensity of the subsequent hydrothermal aging conditions, and the alkaline auxiliary agent provides hydroxyl groups, so that the amorphous precipitate is slowly and evenly transformed into the pseudo-boehmite crystal form, and crystal nuclei are generated during the aging process, and explosive growth begins to form pseudo-boehmite with a large pore volume. In summary, low impurities and ultra-large pore volume of pseudo-boehmite are achieved simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 A schematic flow chart of a method for preparing pseudo-boehmite provided in an embodiment of the present application;

[0023] Figure 2 A microstructure diagram of pseudo-boehmite provided in an embodiment of the present application;

[0024] Figure 3 This is an XRD diagram of pseudo-boehmite provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0026] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have 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 within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0027] In addition, in the description of the specification of the present application, the terms "include", "comprise", etc. mean "including but not limited to". In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple, respectively.

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

[0029] At present, the mainstream processes for macroporous pseudo-boehmite are carbonation method and double aluminum method. Because the carbonation method is easy to produce impurities and is difficult to control, which affects the purity of pseudo-boehmite, the double aluminum method is mainly used. However, the pore volume of macroporous pseudo-boehmite produced by the double aluminum method on the market is generally between 1.0-1.2ml / g, and the acidic components in the double aluminum method will bring in impurities. For example, when aluminum sulfate is used as the acidic component, sulfate ions are not easy to remove, and when aluminum chloride is used as the acidic component, chloride ions are not easy to remove, which makes it difficult to meet the requirements for pore volume and impurities in the preparation process of special catalysts. Therefore, in the first aspect, the present application provides a method for preparing pseudo-boehmite, Figure 1 A schematic diagram of a preparation method of pseudo-boehmite provided in the embodiment of the present application; see Figure 1 , the method comprising:

[0030] S1, neutralizing sodium aluminate and acidic aluminum salt to generate an amorphous precipitate to obtain a first slurry;

[0031] In some embodiments, the acidic aluminum salt includes at least one of the following: aluminum sulfate, aluminum chloride, and sodium acetate.

[0032] In the embodiment of the present application, sodium aluminate is alkaline and can undergo a neutralization reaction with an acidic aluminum salt, and the acidic aluminum salt can be a combination of one or more of aluminum sulfate, aluminum chloride, and sodium acetate.

[0033] In some embodiments, the sodium aluminate meets the following indicators: a caustic ratio αK of 1.4 to 2.5, and an alumina content of 30 g / L to 150 g / L.

[0034] In the embodiment of the present application, the caustic ratio αK of sodium aluminate can be 1.4 to 2.5, which can stabilize the pH during the neutralization reaction and ensure the uniformity of the reaction. The alumina content of sodium aluminate is 30g / L to 150g / L, which can ensure the output rate of pseudo-boehmite and provide a more powerful reaction space for the neutralization reaction system, which is conducive to removing more impurities. If the alumina content of the sodium aluminate is higher than 150g / L, it will affect the uniformity of the neutralization reaction process to a certain extent, resulting in part of the precipitate generated by the neutralization reaction not being amorphous, which is not conducive to subsequent filtration and impurity removal; at the same time, in the subsequent aging process, it affects the uniformity of crystallization; if the alumina content is lower than 30g / L, it will cause the output rate of pseudo-boehmite to be reduced to a certain extent, and the production cost will increase. Exemplarily, the caustic ratio αK of the sodium aluminate can be 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.5, etc.; the alumina content of sodium aluminate can be 30g / L, 40g / L, 50g / L, 60g / L, 70g / L, 80g / L, 90g / L, 100g / L, 110g / L, 120g / L, 130g / L, 140g / L, 150g / L, etc.

[0035] In some embodiments, the process parameters of the neutralization reaction include: pH value 5.5-7.0, temperature 10°C-65°C.

[0036] In the embodiment of the present application, the pH value of the neutralization reaction can be 5.5-7.0, which can ensure that only amorphous precipitates (amorphous) are generated during the neutralization reaction, and no products of other crystalline forms are produced. If the pH value of the neutralization reaction is higher than 7.0, it will cause crystals to be produced during the neutralization reaction to a certain extent, which is difficult to remove impurities, and miscellaneous crystals of gibbsite may be produced; if the pH value of the neutralization reaction is lower than 5.5, it will cause excessive acidic impurities in the product to a certain extent, which is difficult to remove impurities. The temperature of the neutralization reaction is 10°C-65°C, which can reduce the neutralization reaction rate, avoid too fast reaction, and cause the reaction to be uneven and local agglomeration, affecting the crystallization performance during subsequent aging. Exemplarily, the pH value of the above-mentioned neutralization reaction can be 5.5, 6.0, 6.5, 7.0, etc.; the temperature of the above-mentioned neutralization reaction can be 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 65°C, etc. In addition, the time of the neutralization reaction needs to be determined by the capacity of the neutralization reaction tank.

[0037] S2, filtering the first slurry, and then beating the filter cake obtained by filtration to obtain a second slurry;

[0038] In the embodiment of the present application, the first slurry is filtered to reduce the acidic component impurities in the amorphous precipitate. The weight concentration of the filter cake in the second slurry is 10% to 20%.

[0039] S3. Using an alkaline auxiliary agent, the pH value of the second slurry is adjusted to a preset pH value, so that the second slurry is aged to obtain pseudo-boehmite.

[0040] In the embodiment of the present application, the above-mentioned neutralization reaction generates an amorphous precipitate, which is acidic and difficult to grow into a crystalline phase of pseudo-boehmite during the aging process. By adding an alkaline auxiliary agent, the amorphous precipitate is aged and crystallized normally in an alkaline environment, so that the amorphous precipitate is transformed into a pseudo-boehmite crystalline phase, and the stronger the alkalinity, the higher the crystallization kinetics, the higher the pseudo-boehmite crystallinity, and the denser the crystal morphology. Therefore, under the action of the alkaline auxiliary agent, the amorphous state is explosively grown to expand the pore volume, and pseudo-boehmite with low impurities and ultra-large pore volume can be obtained. The second slurry containing pseudo-boehmite obtained in step S3 is subjected to multiple solid-liquid separation and washing to obtain a filter cake, and the filter cake is dried to obtain pseudo-boehmite.

[0041] In some embodiments, the preset pH value is 7.5-10.0.

[0042] In the embodiment of the present application, the preset pH value can be 7.0-10, which provides sufficient hydroxyl groups for the aging process, so that the amorphous state is converted into a pseudo-thin water state. If the preset pH value is higher than 10.0, the amorphous state will rapidly nucleate, the grains will quickly agglomerate, and the pore volume will be difficult to grow. Exemplarily, the above preset pH value can be 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, etc.

[0043] In some embodiments, the aging process parameters include: temperature 75° C. to 100° C., time 30 min to 210 min.

[0044] In the embodiment of the present application, the aging temperature can be 75°C to 100°C, and the aging time can be 30min to 210min, which can ensure the perfection and uniformity of the aging crystallization, thereby generating pseudo-boehmite with a large pore volume. Exemplarily, the aging temperature can be 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, etc.; the aging time can be 30min, 50min, 70min, 90min, 100min, 120min, 140min, 150min, 170min, 190min, 200min, 210min, etc.

[0045] In some embodiments, the alkaline auxiliary agent includes at least one of the following: Na2CO3, NaOH, NaNH2.

[0046] In the embodiment of the present application, the alkaline auxiliary agent can be a strong base / sub-strong base auxiliary agent containing no chloride ions and sodium ions, which can avoid impurities from being brought into the process system and affecting the purity of the product. Furthermore, the strong base auxiliary agent can provide more hydroxyl content, which can enhance the aging reaction effect, shorten the aging time, and improve the production efficiency in the actual production process; at the same time, the strong base is conducive to breaking the ion balance of the acidic components in the solution system, accelerating the formation of the corresponding salt, and facilitating the precipitation from the precipitate and dissolving in the solution system to achieve the purpose of impurity removal. The alkaline auxiliary agent can be a combination of one or more of Na2CO3, NaOH, and NaNH2.

[0047] In some embodiments, the concentration of the alkaline auxiliary agent is 10 g / L to 120 g / L.

[0048] In the embodiment of the present application, the concentration of the alkaline auxiliary agent can be 10g / L to 120g / L. After the alkaline auxiliary agent is dissolved, it will be ionized into hydroxyl groups. The hydroxyl groups can provide crystal water for amorphous alumina, and can provide more n values ​​for AlOOH·nH2O (pseudo-thin water), thereby promoting the crystallization of the pseudo-thin water phase. If the concentration of the alkaline auxiliary agent is lower than 10g / L, it is difficult to provide sufficient hydroxyl groups for the aging crystallization process to a certain extent, and it is difficult to convert the amorphous state into the pseudo-thin water state; if the concentration of the alkaline auxiliary agent is higher than 120g / L, it will cause the amorphous state to rapidly nucleate to a certain extent, the pseudo-thin crystal grains will quickly agglomerate, and the pore volume will be difficult to grow. Exemplarily, the concentration of the above-mentioned alkaline auxiliary agent can be 10g / L, 20g / L, 30g / L, 40g / L, 50g / L, 60g / L, 70g / L, 80g / L, 90g / L, 100g / L, 110g / L, 120g / L, etc.

[0049] The preparation method of the above-mentioned pseudo-boehmite is illustratively, taking sodium aluminate solution and aluminum sulfate as raw materials, preparing the required sodium aluminate concentration by using soft water, using kettle equipment as neutralization equipment, and reacting the two raw materials in parallel and adding them simultaneously to synthesize an amorphous precipitate, filtering the synthesized colloid to remove impurities, and after the filtration, the solid is slurried evenly with soft water, and then enters an aging kettle, and alkaline additives are added to increase the crystallization kinetics to prepare macroporous pseudo-boehmite.

[0050] In a second aspect, the present application provides pseudo-boehmite prepared by the method described in any one of the first aspects.

[0051] In some embodiments, the pseudo-boehmite meets the following indicators: a pore volume greater than 1.2 ml / g, and an impurity content of the acidic component less than 0.5 wt %.

[0052] In the embodiments of the present application, an amorphous precipitate (colloid) with complete morphology is generated by the above-mentioned neutralization reaction. After the amorphous precipitate is decontaminated, an alkaline additive is added to provide kinetic energy, and the amorphous precipitate is formed into a pseudo-boehmite with a higher pore volume under certain aging conditions, thereby obtaining a pseudo-boehmite that meets the following indicators: a pore volume greater than 1.2 ml / g, and an impurity content of an acidic component less than 0.5 wt%, thereby improving product performance and meeting the use requirements of large-pore pseudo-boehmite in the hydrocracking catalyst industry. Figure 2 A microstructure diagram of pseudo-boehmite provided in the embodiment of the present application; see Figure 2 , indicating that the pseudo-boehmite has an extremely large pore volume. Figure 3 This is an XRD diagram of a pseudo-boehmite provided in the embodiment of the present application; see Figure 3 , indicating that pseudo-boehmite was successfully prepared.

[0053] The pseudo-boehmite is realized based on the preparation method of the pseudo-boehmite mentioned above. The specific steps of the preparation method of the pseudo-boehmite can refer to the above embodiment. Since the pseudo-boehmite adopts part or all of the technical solutions of the above embodiment, it at least has all the beneficial effects brought by the technical solutions of the above embodiment, which will not be described one by one here.

[0054] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0055] Example 1

[0056] A method for preparing pseudo-boehmite, comprising:

[0057] (1) neutralizing sodium aluminate and an acidic aluminum salt to generate an amorphous precipitate to obtain a first slurry; wherein the sodium aluminate meets the following indicators: αK is 1.5, and the aluminum oxide content is 95 g / L; the acidic aluminum salt is aluminum sulfate, and the process parameters of the neutralization reaction include: temperature is 45° C., and pH value is 6.8;

[0058] (2) filtering the first slurry, and then beating the filter cake obtained by filtration to obtain a second slurry; wherein the weight concentration of the filter cake in the second slurry is 10%;

[0059] (3) Using an alkaline auxiliary agent, the pH value of the second slurry is adjusted to a preset pH value, so as to age the second slurry to obtain a second slurry containing pseudo-boehmite; wherein the alkaline auxiliary agent is Na2CO3; the concentration of the alkaline auxiliary agent is 70 g / L, the preset pH value is 8.5, and the aging process parameters include: temperature of 90°C and time of 120 min.

[0060] (4) subjecting the second slurry containing pseudo-boehmite to multiple solid-liquid separation and washing to obtain a filter cake, and drying the filter cake to obtain a pseudo-boehmite finished product.

[0061] Example 2

[0062] A method for preparing pseudo-boehmite, comprising:

[0063] (1) neutralizing sodium aluminate and an acidic aluminum salt to generate an amorphous precipitate to obtain a first slurry; wherein the sodium aluminate meets the following indicators: αK is 1.5, and the aluminum oxide content is 95 g / L; the acidic aluminum salt is aluminum sulfate, and the process parameters of the neutralization reaction include: temperature is 60° C., and pH value is 7.0;

[0064] (2) filtering the first slurry, and then beating the filter cake obtained by filtration to obtain a second slurry; wherein the weight concentration of the filter cake in the second slurry is 10%;

[0065] (3) Using an alkaline auxiliary agent to adjust the pH value of the second slurry to a preset pH value, so as to age the second slurry to obtain a second slurry containing pseudo-boehmite; wherein the alkaline auxiliary agent is Na2CO3; the concentration of the alkaline auxiliary agent is 70 g / L, the preset pH value is 9.0, and the aging process parameters include: temperature of 100°C and time of 150 min.

[0066] (4) subjecting the second slurry containing pseudo-boehmite to multiple solid-liquid separation and washing to obtain a filter cake, and drying the filter cake to obtain a pseudo-boehmite finished product.

[0067] Example 3

[0068] A method for preparing pseudo-boehmite, comprising:

[0069] (1) neutralizing sodium aluminate and an acidic aluminum salt to generate an amorphous precipitate to obtain a first slurry; wherein the sodium aluminate meets the following indicators: αK is 1.5 and the aluminum oxide content is 70 g / L; the acidic aluminum salt is aluminum sulfate, and the process parameters of the neutralization reaction include: temperature is 30° C. and pH value is 6.5;

[0070] (2) filtering the first slurry, and then beating the filter cake obtained by filtration to obtain a second slurry; wherein the weight concentration of the filter cake in the second slurry is 10%;

[0071] (3) Using an alkaline auxiliary agent to adjust the pH value of the second slurry to a preset pH value, so as to age the second slurry to obtain a second slurry containing pseudo-boehmite; wherein the alkaline auxiliary agent is Na2CO3; the concentration of the alkaline auxiliary agent is 70 g / L, the preset pH value is 8.0, and the aging process parameters include: temperature of 75°C and time of 160 min.

[0072] (4) subjecting the second slurry containing pseudo-boehmite to multiple solid-liquid separation and washing to obtain a filter cake, and drying the filter cake to obtain a pseudo-boehmite finished product.

[0073] Example 4

[0074] A method for preparing pseudo-boehmite, comprising:

[0075] (1) neutralizing sodium aluminate and an acidic aluminum salt to generate an amorphous precipitate to obtain a first slurry; wherein the sodium aluminate meets the following indicators: αK is 1.5 and the aluminum oxide content is 60 g / L; the acidic aluminum salt is aluminum sulfate, and the process parameters of the neutralization reaction include: temperature is 35° C. and pH value is 6.3;

[0076] (2) filtering the first slurry, and then beating the filter cake obtained by filtration to obtain a second slurry; wherein the weight concentration of the filter cake in the second slurry is 10%;

[0077] (3) Using an alkaline auxiliary agent, the pH value of the second slurry is adjusted to a preset pH value, so as to age the second slurry to obtain a second slurry containing pseudo-boehmite; wherein the alkaline auxiliary agent is Na2CO3; the concentration of the alkaline auxiliary agent is 70 g / L, the preset pH value is 9.0, and the aging process parameters include: temperature of 75°C and time of 160 min.

[0078] (4) subjecting the second slurry containing pseudo-boehmite to multiple solid-liquid separation and washing to obtain a filter cake, and drying the filter cake to obtain a pseudo-boehmite finished product.

[0079] Example 5

[0080] A method for preparing pseudo-boehmite, comprising:

[0081] (1) neutralizing sodium aluminate and an acidic aluminum salt to generate an amorphous precipitate to obtain a first slurry; wherein the sodium aluminate meets the following indicators: αK is 1.5 and the aluminum oxide content is 40 g / L; the acidic aluminum salt is aluminum sulfate, and the process parameters of the neutralization reaction include: temperature is 35° C. and pH value is 6.2;

[0082] (2) filtering the first slurry, and then beating the filter cake obtained by filtration to obtain a second slurry; wherein the weight concentration of the filter cake in the second slurry is 10%;

[0083] (3) Using an alkaline additive to adjust the pH value of the second slurry to a preset pH value, so as to age the second slurry to obtain a second slurry containing pseudo-boehmite; wherein the alkaline additive is Na2CO3; the concentration of the alkaline additive is 50 g / L, the preset pH value is 8.5, and the aging process parameters include: temperature of 70°C and time of 200 min.

[0084] (4) subjecting the second slurry containing pseudo-boehmite to multiple solid-liquid separation and washing to obtain a filter cake, and drying the filter cake to obtain a pseudo-boehmite finished product.

[0085] Comparative Example 1

[0086] A method for preparing pseudo-boehmite, comprising:

[0087] (1) neutralizing sodium aluminate and an acidic aluminum salt to generate an amorphous precipitate to obtain a first slurry; wherein the sodium aluminate meets the following indicators: αK is 1.5, and the aluminum oxide content is 40 g / L; the acidic aluminum salt is aluminum sulfate, and the process parameters of the neutralization reaction include: temperature is 30° C., and pH value is 6.0;

[0088] (2) Using an alkaline auxiliary agent to adjust the pH value of the first slurry to a preset pH value, so as to age the first slurry and obtain a second slurry containing pseudo-boehmite; wherein the alkaline auxiliary agent is Na2CO3. The concentration of the alkaline auxiliary agent is 50 g / L, the preset pH value is 7.5, and the aging process parameters include: temperature of 60°C and time of 50 min.

[0089] (3) subjecting the second slurry containing pseudo-boehmite to multiple solid-liquid separation and washing to obtain a filter cake, and drying the filter cake to obtain a pseudo-boehmite finished product.

[0090] Comparative Example 2

[0091] A method for preparing pseudo-boehmite, comprising:

[0092] (1) neutralizing sodium aluminate and an acidic aluminum salt to generate an amorphous precipitate to obtain a first slurry; wherein the sodium aluminate meets the following indicators: αK is 1.5 and the aluminum oxide content is 80 g / L; the acidic aluminum salt is aluminum sulfate, and the process parameters of the neutralization reaction include: temperature is 40° C. and pH value is 9.5;

[0093] (2) filtering the first slurry, and then beating the filter cake obtained by filtration to obtain a second slurry; wherein the weight concentration of the filter cake in the second slurry is 10%;

[0094] (4) Using an alkaline auxiliary agent, the pH value of the second slurry is adjusted to a preset pH value, so as to age the second slurry to obtain a second slurry containing pseudo-boehmite; wherein the alkaline auxiliary agent is Na2CO3; the concentration of the alkaline auxiliary agent is 60 g / L, the preset pH value is 8.0, and the aging process parameters include: temperature of 70°C and time of 80 min.

[0095] (4) subjecting the second slurry containing pseudo-boehmite to multiple solid-liquid separation and washing to obtain a filter cake, and drying the filter cake to obtain a pseudo-boehmite finished product.

[0096] Comparative Example 3

[0097] A method for preparing pseudo-boehmite, comprising:

[0098] (1) neutralizing sodium aluminate and an acidic aluminum salt to generate an amorphous precipitate to obtain a first slurry; wherein the sodium aluminate meets the following indicators: αK is 1.5, and the aluminum oxide content is 95 g / L; the acidic aluminum salt is aluminum sulfate, and the process parameters of the neutralization reaction include: temperature is 45° C., and pH value is 6.8;

[0099] (2) filtering the first slurry, and then beating the filter cake obtained by filtration to obtain a second slurry; wherein the weight concentration of the filter cake in the second slurry is 10%;

[0100] (3) Using an alkaline auxiliary agent to adjust the pH value of the second slurry to a preset pH value, so as to age the second slurry to obtain a second slurry containing pseudo-boehmite; wherein the alkaline auxiliary agent is Na2CO3. The concentration of the alkaline auxiliary agent is 170 g / L, the preset pH value is 8.5, and the aging process parameters include: temperature of 90°C and time of 120 min.

[0101] (4) subjecting the second slurry containing pseudo-boehmite to multiple solid-liquid separation and washing to obtain a filter cake, and drying the filter cake to obtain a pseudo-boehmite finished product.

[0102] The pseudo-boehmite prepared in Examples 1-5 and Comparative Examples 1-3 was tested for indicators, and the test results are shown in Table 1, wherein the sulfuric acid content is the impurity content in the acidic component.

[0103] Table 1 Index test results of pseudo-boehmite

[0104]

[0105]

[0106] From Table 1 above, it can be seen that the pseudo-boehmite has low SO4 2-The content is less than 0.5wt%, and the pore volume is more than 1.2ml / g, which meets the use requirements of macroporous pseudo-boehmite in the hydrocracking catalyst industry. However, in Comparative Example 1, the first slurry is not filtered to remove impurities; the pH of the neutralization reaction in Comparative Example 2 is too high; and the concentration of the alkaline additive in Comparative Example 3 is too high, which will affect the index test results of pseudo-boehmite to a certain extent, which are worse than those of Examples 1 to 5.

[0107] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0108] (1) obtaining an amorphous precipitate at a neutralization temperature, pH value and raw material concentration and removing impurities from the amorphous precipitate, and then subjecting the amorphous precipitate to an aging treatment process after removing impurities, controlling the pH value, temperature and alkaline auxiliary agent concentration of the system, and obtaining pseudo-boehmite with low impurities and ultra-large pore volume, thereby meeting the use requirements of the hydrocracking catalyst industry for pseudo-boehmite;

[0109] (2) Based on the neutralization process, a double aluminum method is used to prepare macroporous pseudo-boehmite with a pore volume greater than 1.2 ml / g and an impurity content of acidic components less than 0.5%, thereby improving product performance;

[0110] (3) The preparation method of pseudo-boehmite provided in the embodiment of the present application has a simple process and is easy to implement and operate. It is also combined with the actual production of pseudo-boehmite, which is conducive to promotion and application.

[0111] The above description is only a specific implementation of the present application, so that those skilled in the art can 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 the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for preparing pseudo-boehmite, characterized in that: The method comprises: The sodium metaaluminate and the acidic aluminum salt are subjected to a neutralization reaction to generate an amorphous precipitate to obtain a first slurry; The first slurry is filtered, and then the filter cake obtained by filtration is beaten to obtain a second slurry; The pH value of the second slurry is adjusted to a preset pH value using an alkaline auxiliary agent, so that the second slurry is aged to obtain pseudo-boehmite.

2. The method according to claim 1, characterized in that The acidic aluminum salt includes at least one of the following: aluminum sulfate, aluminum chloride, and sodium acetate.

3. The method according to claim 1, characterized in that The sodium aluminate meets the following indicators: a caustic ratio αK of 1.4 to 2.5, and an alumina content of 30 g / L to 150 g / L.

4. The method according to claim 1, characterized in that The process parameters of the neutralization reaction include: pH value 5.5-7.0, temperature 10°C-65°C.

5. The method according to claim 1, characterized in that The preset pH value is 7.5-10.

0.

6. The method according to claim 1 or 5, characterized in that: The aging process parameters include: temperature 75° C. to 100° C., time 30 min to 210 min.

7. The method according to claim 1, characterized in that The alkaline auxiliary agent includes at least one of the following: Na2CO3, NaOH, and NaNH2.

8. The method according to claim 1 or 7, characterized in that: The concentration of the alkaline auxiliary agent is 10 g / L to 120 g / L.

9. Pseudo-boehmite prepared by the method according to any one of claims 1 to 8.

10. The pseudo-boehmite according to claim 9, characterized in that: The pseudo-boehmite meets the following indicators: the pore volume is greater than 1.2 ml / g, and the impurity content of the acidic component is less than 0.5 wt%.

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