Preparation method of pseudo-boehmite with high bulk specific gravity

Abstract

The invention provides a preparation method of pseudo-boehmite with high bulk specific gravity, and belongs to the field of pseudo-boehmite. The method comprises the following steps: carrying out a low-temperature neutralization reaction on an aluminum salt solution and a sodium metaaluminate solution, and keeping the pH value of a neutralized material at 6-6.5 in the reaction process to obtain amorphous precursor slurry; carrying out solid-liquid separation on the amorphous precursor slurry to obtain first mixed slurry; performing high-temperature aging crystal transformation reaction on the first mixed slurry and sodium carbonate to obtain macroporous pseudo-boehmite slurry; performing solid-liquid separation on the macroporous pseudo-boehmite slurry to obtain second mixed slurry; carrying out modification treatment on the second mixed slurry and acid or acid aluminum salt so as to re-agglomerate the non-peptized macroporous pseudo-boehmite to obtain third slurry; performing solid-liquid separation on the third slurry to obtain fourth mixed slurry; and carrying out spray drying on the fourth mixed slurry to obtain the pseudo-boehmite. Therefore, the bulk density of the pseudo-boehmite is improved.

Description

Technical Field

[0001] The present application relates to the technical field of pseudo-boehmite, and in particular to a method for preparing pseudo-boehmite with high bulk density. Background Art

[0002] In the petroleum refining and petrochemical industries, catalytic reactors are divided into fixed bed reactors (Packed Bed Reactor), fluidized bed reactors (Fluidized Bed Reactor) and moving bed reactors (Moving Bed Reactor). In addition to the need to comprehensively consider reaction kinetics, thermodynamics and engineering factors in the design of the catalytic reaction bed, these catalytic reactions also have strict requirements on the loaded catalyst, such as catalyst purity, particle size, pore volume, specific surface area and other factors. In addition, the bulk density of the catalyst is also an important indicator that cannot be ignored. For example, in the continuous reforming process, the catalyst slowly moves downward and contacts with countercurrent or cocurrent reactants. In addition, special requirements are placed on the raw material (pseudo-boehmite) for manufacturing the catalyst, which has a pore volume greater than 0.6mL / g and a bulk density greater than 0.7g / mL.

[0003] Currently, known pseudo-boehmite produced by carbonization and neutralization methods is categorized by pore volume into large-pore pseudo-boehmite and small-pore pseudo-boehmite. Large-pore pseudo-boehmite has a pore volume of 0.8-1.3 mL / g and a bulk density of 0.15-0.3 g / mL; small-pore pseudo-boehmite has a pore volume of 0.3-0.5 mL / g and a bulk density of 0.4-0.7 g / mL. These pseudo-boehmites generally suffer from low bulk densities, making their bulk density alone insufficient to meet the requirements of continuous reforming catalytic processes. Summary of the Invention

[0004] The present application provides a method for preparing pseudo-boehmite with high bulk density to solve the following technical problem: how to increase the bulk density of pseudo-boehmite.

[0005] The present invention provides a method for preparing pseudo-boehmite with a high bulk density, the method comprising:

[0006] Aluminum salt solution and sodium metaaluminate solution are subjected to low-temperature neutralization reaction, and the pH value of the neutralized material is maintained at 6 to 6.5 during the reaction process to obtain an amorphous precursor slurry;

[0007] The amorphous precursor slurry is subjected to solid-liquid separation, and the filter cake is hydrated to obtain a first mixed slurry;

[0008] subjecting the first mixed slurry to a high-temperature aging crystallization reaction with sodium carbonate to obtain a macroporous pseudo-boehmite slurry;

[0009] performing solid-liquid separation on the macroporous pseudo-boehmite slurry, and adding water to the filter cake to form a slurry to obtain a second mixed slurry;

[0010] Modifying the second mixed slurry with an acid or an acidic aluminum salt to re-agglomerate the un-peptized macroporous pseudo-boehmite to obtain a third slurry;

[0011] Performing solid-liquid separation on the third slurry and adding water to the filter cake to obtain a fourth mixed slurry; and

[0012] The fourth mixed slurry is spray-dried to obtain pseudo-boehmite.

[0013] Optionally, the aluminum oxide concentration of the aluminum salt solution is 50 g / L to 120 g / L, and the aluminum oxide concentration of the sodium metaaluminate solution is 50 g / L to 120 g / L.

[0014] Optionally, the aluminum oxide concentration of the aluminum salt solution is 80 g / L to 100 g / L, and the aluminum oxide concentration of the sodium metaaluminate solution is 80 g / L to 100 g / L.

[0015] Optionally, the temperature of the low-temperature neutralization reaction is 10° C. to 30° C., and the time of the low-temperature neutralization reaction is 60 min to 120 min.

[0016] Optionally, the high-temperature aging crystallization reaction meets the following conditions: reaction temperature is 80°C to 100°C, reaction time is 1h to 6h, and reaction pH is 7.5 to 10.

[0017] Optionally, the peptization performance of the macroporous pseudo-boehmite in the macroporous pseudo-boehmite slurry is 20% to 50%.

[0018] Optionally, the modification treatment meets the following conditions: temperature of 99° C. to 120° C., holding time of 0.5 h to 1 h, pH value of 6.5 to 7, and stirring speed ≥400 rev / min.

[0019] Optionally, the acid includes one or more of nitric acid, acetic acid and sulfuric acid, and the acidic aluminum salt includes one or more of aluminum nitrate, aluminum chloride and aluminum sulfate.

[0020] Optionally, the solid content of the fourth mixed slurry is less than 10%.

[0021] Optionally, the pseudo-boehmite meets the following properties: bulk density of 0.7012 g / mL to 0.7672 g / mL, pore volume of 0.6002 mL / g to 0.6927 mL / g, specific surface area of 283.7 m 2 / g~342.4m 2 / g.

[0022] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0023] The embodiment of the present application provides a preparation method of high-bulk-density pseudo-boehmite, which includes: subjecting an aluminum salt solution and a sodium aluminate solution to a low-temperature neutralization reaction, and maintaining the pH value of the neutralized material at 6-6.5 during the reaction process to obtain an amorphous precursor slurry; subjecting the amorphous precursor slurry to solid-liquid separation, and filtering the cake to hydration to obtain a first mixed slurry; subjecting the first mixed slurry to a high-temperature aging crystallization reaction with sodium carbonate to obtain a macroporous pseudo-boehmite slurry; subjecting the macroporous pseudo-boehmite slurry to solid-liquid separation, and filtering the cake to hydration to obtain a second mixed slurry; subjecting the second mixed slurry to a modification treatment with an acid or an acidic aluminum salt to re-agglomerate the unpeptized macroporous pseudo-boehmite, and obtaining a third slurry; subjecting the third slurry to solid-liquid separation, and filtering the cake to hydration to obtain a fourth mixed slurry; and spray drying the fourth mixed slurry to obtain pseudo-boehmite. First, through low-temperature neutralization reaction, the formation of β-Al(OH)3 impurities is effectively inhibited, ensuring the stability of the amorphous precursor and providing a controllable basis for subsequent aging and crystallization; second, during high-temperature aging, sodium carbonate adjusts the pH and replaces sulfate / nitrate to avoid the introduction of impurity cations and ensure product purity; third, through high-temperature acid treatment, the surface peptized part is dissolved, and the un-peptized particles are caused to re-agglomerate, significantly increasing the bulk density while retaining the pore volume and specific surface area; finally, through spray drying, the particle morphology is precisely controlled to obtain pseudo-boehmite, thereby increasing the bulk density of the pseudo-boehmite. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] 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.

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0026] Figure 1 A schematic flow chart of a method for preparing pseudo-boehmite with high bulk density provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0028] 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 hard 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 numbers within the range. For example, the description of a range 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 applies 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.

[0029] In addition, in the description of the specification of this application, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational 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 these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to 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 or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple. "Parts" such as parts by weight and parts by mass represent the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one-to-one to the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0030] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0031] Figure 1 A schematic flow chart of a method for preparing pseudo-boehmite with high bulk density provided in an embodiment of the present application.

[0032] like Figure 1 As shown, the present application provides a method for preparing pseudo-boehmite with high bulk density, the method comprising:

[0033] S1. neutralizing an aluminum salt solution and a sodium metaaluminate solution at low temperature, and maintaining the pH value of the neutralized material at 6 to 6.5 during the reaction process to obtain an amorphous precursor slurry;

[0034] Maintaining the pH value of the neutralized material at 6 to 6.5 during the reaction process can inhibit crystal transformation (such as the formation of β-Al(OH)3), which is conducive to obtaining a stable amorphous form and ensuring the controllability of the crystal form in the subsequent aging step. If the pH is lower than 6, the reaction is incomplete and the raw materials are wasted; if the pH is higher than 6.5, crystal transformation is likely to occur. Exemplarily, the pH value of the neutralized material maintained during the reaction process can be 6, 6.1, 6.2, 6.3, 6.4, 6.5, etc.

[0035] In some embodiments, the aluminum salt solution has an aluminum oxide concentration of 50 g / L to 120 g / L, and the sodium metaaluminate solution has an aluminum oxide concentration of 50 g / L to 120 g / L.

[0036] The aluminum oxide concentration of the aluminum salt and the sodium metaaluminate is limited to 50 g / L to 120 g / L. The aluminum salt (such as aluminum nitrate, aluminum sulfate) reacts with the sodium metaaluminate solution to form an amorphous precursor to avoid rapid crystallization due to excessively high concentration to form a mixed phase (such as Bayerite), or too slow a reaction rate due to too low a concentration. Exemplarily, the aluminum oxide concentration of the aluminum salt solution can be 50 g / L, 60 g / L, 70 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, etc., and the aluminum oxide concentration of the sodium metaaluminate solution can be 50 g / L, 60 g / L, 70 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, etc.

[0037] In some embodiments, the aluminum oxide concentration of the aluminum salt solution is 80 g / L to 100 g / L, and the aluminum oxide concentration of the sodium metaaluminate solution is 80 g / L to 100 g / L.

[0038] In some embodiments, the temperature of the low-temperature neutralization reaction is 10° C. to 30° C., and the time of the low-temperature neutralization reaction is 60 min to 120 min.

[0039] The low-temperature neutralization reaction temperature is 10°C to 30°C, and the time is 60min to 120min, which can slow down the reaction rate, promote uniform nucleation, and form a stable amorphous precursor. For example, the low-temperature neutralization reaction temperature can be 10°C, 12°C, 15°C, 18°C, 20°C, 25°C, 30°C, etc., and the low-temperature neutralization reaction time can be 60min, 70min, 80min, 90min, 100min, 110min, 120min, etc.

[0040] S2, performing solid-liquid separation on the amorphous precursor slurry, and adding water to the filter cake to form a slurry to obtain a first mixed slurry;

[0041] S3, subjecting the first mixed slurry to a high-temperature aging crystallization reaction with sodium carbonate to obtain a macroporous pseudo-boehmite slurry;

[0042] Sodium carbonate is added to adjust the pH value of the slurry. First, the addition of sodium carbonate does not introduce other miscellaneous cations. Second, the introduction of carbonate anions can replace most of the sulfate, nitrate and other anions in the pseudo-boehmite, so that the obtained product meets the requirements of preparing the catalyst carrier and obtains a macroporous pseudo-boehmite slurry.

[0043] In some embodiments, the high-temperature aging crystallization reaction satisfies the following conditions: reaction temperature is 80° C. to 100° C., reaction time is 1 h to 6 h, and reaction pH is 7.5 to 10.

[0044] In some embodiments, the peptization property of the macroporous pseudo-boehmite in the macroporous pseudo-boehmite slurry is 20% to 50%.

[0045] The reaction temperature of the high-temperature aging crystallization reaction is limited to 80°C to 100°C, the reaction time is 1h to 6h, and the reaction pH is 7.5 to 10, which is conducive to the transformation of the amorphous form to the pseudo-boehmite crystal form and is conducive to obtaining a macroporous pseudo-boehmite with a peptization performance of 20% to 50%. If the temperature is higher than 100°C, γ-AlOOH impurities are easily generated, and if the time is less than 1h, the crystallization is incomplete. For example, the reaction temperature can be 80°C, 85°C, 90°C, 95°C, 100°C, etc., the reaction time can be 1h, 2h, 3h, 4h, 5h, 6h, and the reaction pH can be 7.5, 8, 8.5, 9, 9.5, 10, etc.

[0046] In some embodiments, the high-temperature aging crystallization reaction satisfies the following conditions: reaction temperature is 80° C. to 100° C., reaction time is 2 h to 4 h, and reaction pH is 8 to 9.

[0047] S4, performing solid-liquid separation on the macroporous pseudo-boehmite slurry, and adding water to the filter cake to form a slurry to obtain a second mixed slurry;

[0048] S5, modifying the second mixed slurry with an acid or an acidic aluminum salt to re-agglomerate the un-peptized macroporous pseudo-boehmite to obtain a third slurry;

[0049] In the embodiment of the present application, a small amount of acid or acidic aluminum salt is added to react with the macroporous pseudo-boehmite, so that the peptized pseudo-boehmite is dissolved and the unpeptized macroporous pseudo-boehmite is re-condensed to form a tighter structure, thereby achieving the purpose of increasing the bulk density.

[0050] In some embodiments, the modification treatment satisfies the following conditions: temperature of 99° C. to 120° C., holding time of 0.5 h to 1 h, pH value of 6.5 to 7, and stirring speed of ≥400 rev / min.

[0051] The temperature of the modification treatment is limited to 99°C to 120°C, the holding time is 0.5h to 1h, the pH value is 6.5 to 7, and the stirring speed is ≥400rev / min, which can ensure that the pore volume of the pseudo-boehmite meets the requirements of preparing the catalyst support and is not excessively reduced. Secondly, the pseudo-boehmite is surface treated to remove the imperfect crystals outside the pseudo-boehmite particles, thereby increasing the bulk density. Exemplarily, the temperature of the modification treatment can be 99°C, 100°C, 105°C, 110°C, 115°C, 120°C, etc., the holding time can be 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, etc., the pH value can be 6.5, 6.6, 6.7, 6.8, 6.9, 7, etc., and the stirring speed can be 400rev / min, 450rev / min, 500rev / min, 550rev / min, 600rev / min, 650rev / min, etc.

[0052] In some embodiments, the acid includes one or more of nitric acid, acetic acid, and sulfuric acid, and the acidic aluminum salt includes one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate.

[0053] Aluminum acid salts provide Al 3+ Compensate for dissolution losses, maintain aluminum source balance, and avoid the introduction of foreign metal impurities.

[0054] S6, performing solid-liquid separation on the third slurry, and adding water to the filter cake to obtain a fourth mixed slurry;

[0055] In some embodiments, the solid content of the fourth mixed slurry is less than 10%.

[0056] Limiting the solid content of the fourth mixed slurry to less than 10% can reduce the slurry viscosity, prevent nozzle clogging during the spray drying process, and ensure particle dispersion and uniform particle size of the final product. For example, the solid content of the fourth mixed slurry can be 4%, 5%, 6%, 7%, 8%, 9%, 9.5%, etc.

[0057] S7. Spray-drying the fourth mixed slurry to obtain pseudo-boehmite.

[0058] In some embodiments, the pseudo-boehmite satisfies the following properties: bulk density of 0.7012 g / mL to 0.7672 g / mL, pore volume of 0.6002 mL / g to 0.6927 mL / g, specific surface area of 283.7 m 2 / g~342.4m 2 / g.

[0059] The high bulk density (>0.7 mL / g) and high specific surface area (>280 m 2 / g) and mesoporous structure (pore volume 0.6-0.69mL / g) of pseudo-boehmite can improve the dispersion of active components and is suitable for petroleum reforming catalysts.

[0060] In summary, the present invention achieves the following through precise step-by-step control of reaction conditions (pH, temperature, concentration), the synergistic effect of sodium carbonate and acidic aluminum salts, and surface modification and structural optimization: a balance between high bulk density (0.7012 g / mL to 0.7672 g / mL) and high specific surface area / pore volume; the preparation of high-purity pseudo-boehmite free of impurities; and a stable and controllable process suitable for industrial production, meeting the high-performance requirements of petroleum catalyst supports. Specifically, it has the following advantages:

[0061] (1) Precise crystal form control and stability: Low-temperature neutralization reaction (pH 6-6.5) effectively inhibits the formation of impurities such as β-Al(OH)3, ensuring the stability of the amorphous precursor and providing a controllable basis for subsequent aging and crystallization. At the same time, the low-temperature environment of 10-30°C slows down the reaction rate, promotes uniform nucleation, and avoids the formation of impurities such as Bayerite caused by high concentration or high temperature.

[0062] (2) High purity and macroporous structure design: During high temperature aging (80-100°C), sodium carbonate is used to adjust the pH (7.5-10) and replace sulfate / nitrate to avoid the introduction of impurity cations and ensure product purity. At the same time, by controlling the aging conditions (time, pH), a macroporous pseudo-boehmite with a peptization performance of 20%-50% is obtained to meet the high specific surface area of the catalyst carrier (>280m 2 / g) and mesopore requirements (pore volume 0.6002mL / g~0.6927mL / g).

[0063] (3) Bulk density improvement and structural optimization: Through high temperature (99-120℃) acid treatment (pH 6.5-7), the surface peptized part is dissolved, and the un-peptized particles are re-agglomerated, which significantly increases the bulk density (0.7012g / mL-0.7672g / mL) while retaining the pore volume and specific surface area. At the same time, aluminum nitrate, aluminum sulfate and other acidic aluminum salts are used to supplement Al 3+ loss, avoid the introduction of foreign metal impurities, and maintain the balance of aluminum sources.

[0064] (4) Process controllability and product uniformity: The concentration of aluminum salt and sodium metaaluminate (50-120 g / L, preferably 80-100 g / L) ensures a moderate reaction rate and avoids problems such as impurities or incomplete reaction. Furthermore, the solid content of the slurry before spray drying is less than 10%, which reduces viscosity, prevents nozzle clogging, and ensures uniform particle dispersion and consistent particle size of the final product.

[0065] (5) Application adaptability: High specific surface area (283.7m 2 / g~342.4m2 The high molecular weight (m / g) and mesoporous structure (0.6002 mL / g to 0.6927) enhance the dispersion of active components, making it suitable for catalyst supports in applications such as petroleum reforming. Furthermore, controlled process parameters (temperature and time) prevent the formation of high-temperature impurities such as γ-AlOOH, ensuring the thermal stability of the material.

[0066] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are generally measured according to industry standards. If there are no corresponding industry standards, then the methods are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0067] Example 1

[0068] This embodiment provides a method for preparing pseudo-boehmite with a high bulk density, which may include the following steps:

[0069] (1) An aluminum salt solution with an aluminum oxide concentration of 100 g / L and a sodium metaaluminate solution with an aluminum oxide concentration of 100 g / L are mixed and subjected to a low-temperature neutralization reaction at a reaction temperature of 10°C. The pH value of the neutralized material is controlled to be 6 to obtain an amorphous precursor. (2) The amorphous precursor is added with sodium carbonate, the pH is adjusted to 8, and a high-temperature aging crystallization reaction is carried out at a temperature of 80°C and an aging crystallization time of 2.5 hours to obtain a pseudo-boehmite slurry. (3) The pseudo-boehmite slurry is filtered and re-slurried, and aluminum nitrate solution is added dropwise. The slurry pH is controlled to 6.5, the temperature is 99°C, and the temperature is kept for 0.5 hours for modification treatment. The stirring speed is 400 rev / min. (4) The modified slurry is subjected to liquid-solid separation and washed with deionized water 5 times to obtain a qualified pseudo-boehmite filter cake. (5) The qualified pseudo-boehmite filter cake is slurried with deionized water, the solid content is controlled to be less than 10%, and spray dried to obtain a high bulk ratio medium-porous pseudo-boehmite.

[0070] Example 2

[0071] This embodiment provides a method for preparing pseudo-boehmite with a high bulk density, which may include the following steps:

[0072] (1) Aluminum salt solution with an aluminum oxide concentration of 100 g / L and sodium metaaluminate solution with an aluminum oxide concentration of 100 g / L were mixed and subjected to low-temperature neutralization reaction at a reaction temperature of 15°C. The pH value of the neutralized material was controlled to be 6 to obtain an amorphous precursor. (2) Sodium carbonate was added to the amorphous precursor and the pH was adjusted to 8.5. A high-temperature aging and crystallization reaction was carried out at a temperature of 85°C and an aging and crystallization time of 2.5 hours to obtain a pseudo-boehmite slurry. (3) The pseudo-boehmite slurry was filtered and re-slurried, and aluminum nitrate solution was added dropwise. The pH of the slurry was controlled to be 6.5, the temperature was 120 degrees, and the temperature was kept warm for 0.5 hours for modification treatment. The stirring speed was 500 rev / min. (4) The modified slurry was subjected to liquid-solid separation and washed with deionized water 5 times to obtain a qualified pseudo-boehmite filter cake. (5) The qualified pseudo-boehmite filter cake was slurried with deionized water, the solid content was controlled to be less than 10%, and spray-dried to obtain a high-bulk ratio medium-pore pseudo-boehmite.

[0073] Example 3

[0074] This embodiment provides a method for preparing pseudo-boehmite with a high bulk density, which may include the following steps:

[0075] (1) An aluminum salt solution with an aluminum oxide concentration of 100 g / L and a sodium aluminate solution with an aluminum oxide concentration of 100 g / L were mixed and subjected to a low-temperature neutralization reaction at a reaction temperature of 16°C. The pH value of the neutralized material was controlled to be 6.5 to obtain an amorphous precursor. (2) The amorphous precursor was added with sodium carbonate, the pH was adjusted to 8.5, and a high-temperature aging crystallization reaction was carried out at a temperature of 85°C and an aging crystallization time of 2.5 hours to obtain a pseudo-boehmite slurry. (3) The pseudo-boehmite slurry was filtered and re-slurried, and aluminum nitrate solution was added dropwise. The slurry pH was controlled to be 6.5, the temperature was 110 degrees, and the temperature was kept warm for 0.5 hours for modification treatment. The stirring speed was 500 rev / min. (4) The modified slurry was subjected to liquid-solid separation and washed with deionized water 5 times to obtain a qualified pseudo-boehmite filter cake. (5) The qualified pseudo-boehmite filter cake is slurried with deionized water to control the solid content to be less than 10%, and spray-dried to obtain high bulk ratio medium-pore pseudo-boehmite.

[0076] Example 4

[0077] This embodiment provides a method for preparing pseudo-boehmite with a high bulk density, which may include the following steps:

[0078] (1) Aluminum salt solution with an aluminum oxide concentration of 100 g / L and sodium metaaluminate solution with an aluminum oxide concentration of 100 g / L were mixed and subjected to low-temperature neutralization reaction at a reaction temperature of 15°C. The pH value of the neutralized material was controlled to be 6 to obtain an amorphous precursor. (2) Sodium carbonate was added to the amorphous precursor and the pH was adjusted to 8.5. A high-temperature aging and crystallization reaction was carried out at a temperature of 85°C and an aging and crystallization time of 2.5 hours to obtain a pseudo-boehmite slurry. (3) The pseudo-boehmite slurry was filtered and re-slurried, and aluminum nitrate solution was added dropwise. The pH of the slurry was controlled to be 6.5, the temperature was 120 degrees, and the temperature was kept warm for 0.5 hours for modification treatment. The stirring speed was 500 rev / min. (4) The modified slurry was subjected to liquid-solid separation and washed with deionized water 5 times to obtain a qualified pseudo-boehmite filter cake. (5) The qualified pseudo-boehmite filter cake was slurried with deionized water, the solid content was controlled to be less than 10%, and spray-dried to obtain a high-bulk ratio medium-pore pseudo-boehmite.

[0079] Example 5

[0080] This embodiment provides a method for preparing pseudo-boehmite with a high bulk density, which may include the following steps:

[0081] (1) Aluminum salt solution with an aluminum oxide concentration of 100 g / L and sodium metaaluminate solution with an aluminum oxide concentration of 100 g / L were mixed and subjected to low-temperature neutralization reaction at a reaction temperature of 15°C. The pH value of the neutralized material was controlled to be 7 to obtain an amorphous precursor. (2) Sodium carbonate was added to the amorphous precursor, the pH was adjusted to 9, and a high-temperature aging and crystallization reaction was carried out at a temperature of 90°C and an aging and crystallization time of 2.5 hours to obtain a pseudo-boehmite slurry. (3) The pseudo-boehmite slurry was filtered and re-slurried, and aluminum nitrate solution was added dropwise. The slurry pH was controlled to 6.5, the temperature was 120 degrees, and the temperature was kept warm for 0.5 hours for modification treatment. The stirring speed was 500 rev / min. (4) The modified slurry was subjected to liquid-solid separation and washed with deionized water 5 times to obtain a qualified pseudo-boehmite filter cake. (5) The qualified pseudo-boehmite filter cake was slurried with deionized water, the solid content was controlled to be less than 10%, and spray-dried to obtain a high-bulk ratio medium-pore pseudo-boehmite.

[0082] Comparative Example 1

[0083] This comparative example provides a method for preparing pseudo-boehmite with a high bulk density, which may include the following steps:

[0084] (1) An aluminum salt solution with an aluminum oxide concentration of 100 g / L and a sodium metaaluminate solution with an aluminum oxide concentration of 100 g / L are mixed and subjected to a low-temperature neutralization reaction at a reaction temperature of 10°C. The pH value of the neutralized material is controlled to be 6 to obtain an amorphous precursor. (2) The amorphous precursor is added with sodium carbonate, the pH is adjusted to 8, and a high-temperature aging crystallization reaction is carried out at a temperature of 80°C and an aging crystallization time of 2.5 hours to obtain a pseudo-boehmite slurry. (3) The pseudo-boehmite slurry is filtered and re-slurried, and aluminum nitrate solution is added dropwise. The slurry pH is controlled to 6.5, the temperature is 90°C, and the temperature is kept for 0.5 hours for modification treatment. The stirring speed is 400 rev / min. (4) The modified slurry is subjected to liquid-solid separation and washed with deionized water 5 times to obtain a qualified pseudo-boehmite filter cake. (5) The qualified pseudo-boehmite filter cake is slurried with deionized water, the solid content is controlled to be less than 10%, and spray dried to obtain a high bulk ratio medium-porous pseudo-boehmite.

[0085] Comparative Example 2

[0086] This comparative example provides a method for preparing pseudo-boehmite with a high bulk density, which may include the following steps:

[0087] (1) Aluminum salt solution with an aluminum oxide concentration of 100 g / L and sodium metaaluminate solution with an aluminum oxide concentration of 100 g / L were mixed and subjected to low-temperature neutralization reaction at a reaction temperature of 15°C. The pH value of the neutralized material was controlled to be 6 to obtain an amorphous precursor. (2) Sodium carbonate was added to the amorphous precursor and the pH was adjusted to 8.5. A high-temperature aging and crystallization reaction was carried out at a temperature of 85°C and an aging and crystallization time of 0.5 h to obtain a pseudo-boehmite slurry. (3) The pseudo-boehmite slurry was filtered and re-slurried, and aluminum nitrate solution was added dropwise. The pH of the slurry was controlled to be 6.5, the temperature was 120 degrees, and the temperature was kept warm for 0.5 h for modification treatment. The stirring speed was 500 rev / min. (4) The modified slurry was subjected to liquid-solid separation and washed with deionized water 5 times to obtain a qualified pseudo-boehmite filter cake. (5) The qualified pseudo-boehmite filter cake was slurried with deionized water, the solid content was controlled to be less than 10%, and spray-dried to obtain a high-bulk ratio medium-porous pseudo-boehmite.

[0088] Comparative Example 3

[0089] This comparative example provides a method for preparing pseudo-boehmite with a high bulk density, which may include the following steps:

[0090] (1) An aluminum salt solution with an aluminum oxide concentration of 100 g / L and a sodium aluminate solution with an aluminum oxide concentration of 100 g / L were mixed and subjected to a low-temperature neutralization reaction at a reaction temperature of 16°C. The pH value of the neutralized material was controlled to be 7.5 to obtain an amorphous precursor. (2) The amorphous precursor was added with sodium carbonate, the pH was adjusted to 8.5, and a high-temperature aging crystallization reaction was carried out at a temperature of 85°C and an aging crystallization time of 2.5 hours to obtain a pseudo-boehmite slurry. (3) The pseudo-boehmite slurry was filtered and re-slurried, and aluminum nitrate solution was added dropwise. The slurry pH was controlled to 6.5 and the temperature was 110 degrees. The slurry was kept warm for 0.5 hours for modification treatment, and the stirring speed was 500 rev / min. (4) The modified slurry was subjected to liquid-solid separation and washed with deionized water 5 times to obtain a qualified pseudo-boehmite filter cake. (5) The qualified pseudo-boehmite filter cake is slurried with deionized water to control the solid content to be less than 10%, and spray-dried to obtain high bulk ratio medium-pore pseudo-boehmite.

[0091] Comparative Example 4

[0092] This comparative example provides a method for preparing pseudo-boehmite with a high bulk density, which may include the following steps:

[0093] (1) Aluminum salt solution with an aluminum oxide concentration of 100 g / L and sodium metaaluminate solution with an aluminum oxide concentration of 100 g / L were mixed and subjected to low-temperature neutralization reaction at a reaction temperature of 15°C. The pH value of the neutralized material was controlled to be 6 to obtain an amorphous precursor. (2) Sodium carbonate was added to the amorphous precursor and the pH was adjusted to 8.5. A high-temperature aging and crystallization reaction was carried out at a temperature of 85°C and an aging and crystallization time of 2.5 hours to obtain a pseudo-boehmite slurry. (3) The pseudo-boehmite slurry was filtered and re-slurried, and aluminum nitrate solution was added dropwise. The pH of the slurry was controlled to be 6.5, the temperature was 120 degrees, and the temperature was kept warm for 0.5 hours for modification treatment. The stirring speed was 200 rev / min. (4) The modified slurry was subjected to liquid-solid separation and washed with deionized water 5 times to obtain a qualified pseudo-boehmite filter cake. (5) The qualified pseudo-boehmite filter cake was slurried with deionized water, the solid content was controlled to be less than 10%, and spray-dried to obtain a high-bulk ratio mesoporous pseudo-boehmite.

[0094] Comparative Example 5

[0095] This comparative example provides a method for preparing pseudo-boehmite with a high bulk density, which may include the following steps:

[0096] (1) An aluminum salt solution with an aluminum oxide concentration of 100 g / L and a sodium aluminate solution with an aluminum oxide concentration of 100 g / L are mixed and subjected to a low-temperature neutralization reaction at a reaction temperature of 15°C. The pH value of the neutralized material is controlled to be 7 to obtain an amorphous precursor. (2) The amorphous precursor is added with sodium carbonate, the pH is adjusted to 10.5, and a high-temperature aging crystallization reaction is carried out at a temperature of 90°C and an aging crystallization time of 2.5 hours to obtain a pseudo-boehmite slurry. (3) The pseudo-boehmite slurry is filtered and re-slurried, and aluminum nitrate solution is added dropwise. The slurry pH is controlled to 6.5 and the temperature is 120 degrees. The slurry is kept warm for 0.5 hours for modification treatment, and the stirring speed is 500 rev / min. (4) The modified slurry is subjected to liquid-solid separation and washed with deionized water 5 times to obtain a qualified pseudo-boehmite filter cake. (5) The qualified pseudo-boehmite filter cake is slurried with deionized water to control the solid content to be less than 10%, and spray-dried to obtain high bulk ratio medium-pore pseudo-boehmite.

[0097] The properties of the high bulk ratio mesoporous pseudo-boehmite obtained in Examples 1 to 5 and Comparative Examples 1 to 5 were measured, and the results are shown in Table 1.

[0098] Table 1 Properties of high bulk ratio mesoporous pseudo-boehmite of Examples 1 to 5 and Comparative Examples 1 to 5

[0099]

[0100] As shown in Table 1, the bulk density of the pseudo-boehmite obtained in Examples 1 to 5 is 0.7012 g / mL to 0.7672 g / mL, the pore volume is 0.6002 mL / g to 0.6927 mL / g, and the specific surface area is 283.7 m 2 / g~342.4m 2 / g, meeting the requirements for preparing continuous reforming catalysts.

[0101] In Comparative Example 1, due to the low modification temperature (90° C.), the peptization reaction of pseudo-boehmite was incomplete, and the pore volume of the obtained sample was slightly higher, but the bulk ratio was lower.

[0102] In Comparative Example 2, due to insufficient high-temperature crystallization time (0.5 h), the peptization of the obtained macroporous pseudo-boehmite was too low, and thus the modification effect was poor.

[0103] In Comparative Example 3, due to the high pH value (7.5) of the neutralization reaction, the amorphous stability is poor, the pore volume of the obtained macroporous pseudo-boehmite is low, and the pore volume also decreases after modification.

[0104] In Comparative Example 4, due to the low stirring speed (200 rev / min) during modification, the surface treatment effect of the pseudo-boehmite was poor, and the imperfect crystals outside the pseudo-boehmite particles were not effectively removed, so the specific gravity of the obtained pseudo-boehmite pile was low.

[0105] In comparative example 5, due to the high pH value (10.5) of the high-temperature aging crystallization reaction, the peptization of the obtained macroporous pseudo-boehmite increased and the pore volume decreased. Therefore, although the bulk density of the pseudo-boehmite increased significantly after modification, the pore volume also decreased significantly.

[0106] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0107] In the embodiment of the present application, the multi-stage coordinated regulation of low-temperature neutralization to suppress impurities → sodium carbonate-assisted crystallization → acid-modified coagulation → low-solid spray drying is achieved to achieve high bulk density (0.7012 g / mL to 0.7672 g / mL) and high specific surface area (>280 m 2 / g), and mesoporous structure (pore volume 0.6002mL / g~0.6927mL / g), meeting the stringent requirements of petroleum catalyst carriers on mechanical strength, active loading and mass transfer efficiency, with strong process controllability and significant cost-effectiveness.

[0108] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for preparing pseudo-boehmite with high bulk density, the method comprising: Aluminum salt solution and sodium metaaluminate solution are subjected to low-temperature neutralization reaction, and the pH value of the neutralized material is maintained at 6 to 6.5 during the reaction process to obtain an amorphous precursor slurry; The amorphous precursor slurry is subjected to solid-liquid separation, and the filter cake is hydrated to obtain a first mixed slurry; subjecting the first mixed slurry to a high-temperature aging crystallization reaction with sodium carbonate to obtain a macroporous pseudo-boehmite slurry; performing solid-liquid separation on the macroporous pseudo-boehmite slurry, and adding water to the filter cake to form a slurry to obtain a second mixed slurry; Modifying the second mixed slurry with an acid or an acidic aluminum salt to re-agglomerate the un-peptized macroporous pseudo-boehmite to obtain a third slurry; Performing solid-liquid separation on the third slurry and adding water to the filter cake to obtain a fourth mixed slurry; and The fourth mixed slurry is spray-dried to obtain pseudo-boehmite.

2. The method according to claim 1, characterized in that The aluminum oxide concentration of the aluminum salt solution is 50 g / L to 120 g / L, and the aluminum oxide concentration of the sodium metaaluminate solution is 50 g / L to 120 g / L.

3. The method according to claim 2, characterized in that The aluminum oxide concentration of the aluminum salt solution is 80 g / L to 100 g / L, and the aluminum oxide concentration of the sodium metaaluminate solution is 80 g / L to 100 g / L.

4. The method according to claim 1, wherein The temperature of the low-temperature neutralization reaction is 10° C. to 30° C., and the time of the low-temperature neutralization reaction is 60 min to 120 min.

5. The method according to claim 1, wherein The high-temperature aging crystallization reaction meets the following conditions: reaction temperature is 80°C to 100°C, reaction time is 1h to 6h, and reaction pH is 7.5 to 10.

6. The method according to claim 1, wherein The peptization performance of the macroporous pseudo-boehmite in the macroporous pseudo-boehmite slurry is 20% to 50%.

7. The method according to claim 1, characterized in that The modification treatment meets the following conditions: temperature of 99° C. to 120° C., holding time of 0.5 h to 1 h, pH value of 6.5 to 7, and stirring speed of ≥400 rev / min.

8. The method according to claim 1, characterized in that The acid includes one or more of nitric acid, acetic acid and sulfuric acid, and the acidic aluminum salt includes one or more of aluminum nitrate, aluminum chloride and aluminum sulfate.

9. The method according to claim 1, characterized in that The solid content of the fourth mixed slurry is less than 10%.

10. The method according to claim 1, characterized in that The pseudo-boehmite meets the following properties: bulk density of 0.7012 g / mL to 0.7672 g / mL, pore volume of 0.6002 mL / g to 0.6927 mL / g, specific surface area of 283.7 m 2 / g~342.4m 2 / g.

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