High-specific-surface large-pore-volume pseudoboehmite and preparation method therefor and hydrogenation catalyst

Abstract

A high-specific-surface large-pore-volume pseudoboehmite and a preparation method therefor, and a hydrogenation catalyst. The preparation method comprises: mixing and boiling an excess NaOH solution with an associated aluminum ore, and leaching aluminum hydroxide to obtain a sodium metaaluminate solution containing impurities; mixing the sodium metaaluminate solution containing impurities with a precipitant to precipitate the impurities, so as to obtain a purified sodium metaaluminate solution; mixing sulfuric acid and the purified sodium metaaluminate solution and then reacting same to obtain a suspension containing pseudoboehmite; mixing the suspension containing pseudoboehmite with a hydroxycarboxylic acid salt to make the pseudoboehmite be negatively charged, so as to obtain a negatively charged pseudoboehmite suspension; and mixing positively charged aluminum ions with the negatively charged pseudoboehmite suspension to obtain the high-specific-surface large-pore-volume pseudoboehmite. The low-cost hydrogenation catalyst prepared from the high-specific-surface large-pore-volume pseudoboehmite has the characteristics of a high specific surface area and a large pore volume, a higher catalytic activity, a higher impurity capacity, and enhanced market competitiveness.

Description

A high specific surface area and large pore volume pseudoboehmite, its preparation method and hydrogenation catalyst

[0001] This application claims priority to Chinese Patent Application No. 202411433788.5, filed on October 14, 2024, entitled "A High Specific Surface Area Macroporous Volume Phobospore Pseudo-Boehmite and Its Preparation Method and Hydrogenation Catalyst", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to a high specific surface area and large pore volume pseudoboehmite, its preparation method and hydrogenation catalyst, belonging to the field of comprehensive utilization technology of minerals and secondary resources. Background Technology

[0003] The hydrogenation catalyst industry has an urgent need for low-cost, high-quality macroporous boehmite. Macroporous boehmite is one of the main raw materials for hydrogenation catalysts, consuming approximately 1.0-1.3 times its weight of macroporous boehmite per ton of hydrogenation catalyst. The cost and quality of macroporous boehmite directly affect the cost and quality of hydrogenation catalysts. Therefore, developing low-cost, high-quality macroporous boehmite preparation technology has become a research hotspot for researchers in the oil refining industry.

[0004] The traditional production process of macroporous pseudoboehmite uses aluminum hydroxide and aluminum sulfate as raw materials. Sodium hydroxide is used to dissolve the aluminum hydroxide to obtain a sodium aluminate solution, which is then neutralized using aluminum sulfate and sodium aluminate under suitable temperature and pH conditions to obtain macroporous pseudoboehmite. Due to the high prices of aluminum hydroxide and aluminum sulfate, the cost of macroporous pseudoboehmite remains high.

[0005] By-products from metallurgical processes are relatively inexpensive, with aluminum hydroxide as their main component. They can be used to produce low-cost boehmite, but the resulting boehmite's specific surface area, pore volume, and pore size do not meet the requirements of the hydrogenation catalyst industry. For example, CN103693663A discloses a method for recovering bauxite resources in a chromium metallurgical process. Although the recovered aluminum resource is boehmite, the pore volume and specific surface area of ​​this boehmite are very small, far below the requirements of the hydrogenation catalyst industry. CN109279634A discloses a low-cost, high-specific-surface-area boehmite preparation method. While the pore volume and pore size of the obtained boehmite meet the requirements, the specific surface area is too small, and the pore structure is unreasonable, failing to meet the requirements for use as a hydrogenation catalyst.

[0006] Therefore, the production of low-cost, high-quality macroporous pseudoboehmite from associated aluminum ore has become a pressing technical problem in this field. Summary of the Invention

[0007] To address the aforementioned shortcomings and deficiencies, the present invention aims to provide a high-specific-surface-area, large-pore-volume pseudoboehmite and its preparation method. The preparation method provided by this invention uses associated bauxite from the metallurgical industry as raw material to produce low-cost, high-specific-surface-area, large-pore-volume pseudoboehmite that meets the requirements of the petrochemical industry, such as hydrogenation catalysts in oil refining. This method not only increases the content of the target metal in the ore deposit, thereby improving the smelting value and yield of the target metal, but also provides the hydrogenation catalyst industry with low-cost, high-specific-surface-area, large-pore-volume pseudoboehmite.

[0008] To achieve the above objectives, on the one hand, the present invention provides a method for preparing a high specific surface area and large pore volume pseudoboehmite, wherein the preparation method includes:

[0009] Step (1): Mix excess NaOH solution with associated aluminum ore and boil to leach / dissolve aluminum hydroxide, resulting in a sodium aluminate solution containing impurities;

[0010] Step (2): Mix the sodium aluminate solution containing impurities with a precipitant to precipitate the impurities and obtain sodium aluminate purified solution;

[0011] Step (3): After mixing sulfuric acid and sodium aluminate purification solution, react to obtain a suspension containing boehmite;

[0012] Step (4): Mix the suspension containing boehmite with hydroxycarboxylate to make boehmite negatively charged, thus obtaining a negatively charged boehmite suspension.

[0013] Step (5): Mix positively charged aluminum ions and negatively charged boehmite suspension to obtain high specific surface area and large pore volume boehmite.

[0014] As a specific embodiment of the preparation method described above in this invention, the preparation method further includes step (6): mixing the solution obtained in step (5) with the desorbent and washing the resulting mixture.

[0015] In a specific embodiment of the preparation method described above in this invention, the desorbent includes one or a combination of several of ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, and sodium sulfide. The anions of the desorbents such as ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, and sodium sulfide used in step (6) of the preparation method described above can desorb Na+. + and SO4 2- Replace it.

[0016] In step (6) of the preparation method described above, the washing reagent used is deionized water. Rinsing with a large amount of deionized water can remove Na from the system. + and SO4 2- The content was reduced to the value required by the indicator.

[0017] As a specific embodiment of the preparation method described above in this invention, the preparation method further includes step (7): the solution after washing in step (6) is subjected to high temperature and rapid drying to achieve high temperature and rapid dehydration, so as to avoid the hydration effect caused by long-term low temperature dehydration affecting the pore volume and pore structure of the pseudoboehmite, and the high specific surface area and large pore volume pseudoboehmite is obtained after drying.

[0018] In step (7) of the preparation method described above, the drying temperature can be, for example, 100-200℃, and the drying time can be 1-6h.

[0019] As a specific embodiment of the preparation method described above in this invention, in step (1), according to the caustic ratio α k The NaOH solution and associated bauxite are mixed and boiled to a concentration of 1.5-3.0, ensuring an excess of NaOH solution. In this invention, the caustic ratio α... k It refers to the ratio of the amounts of NaOH and Al2O3.

[0020] The target metal is the most abundant in the mineral deposit. After the target metal is extracted through traditional dry metallurgy or hydrometallurgy, the remaining part is a by-product aluminum ore rich in aluminum hydroxide. In this invention, the impurities in the sodium aluminate solution containing impurities may vary for different by-product aluminum ore systems, but generally the main impurities are iron and silicon. Therefore, as a specific embodiment of the preparation method described above in this invention, in step (2), when the impurity is iron, the precipitant is an organic oligomer flocculant, including one or a combination of sodium polyvinyl acetate, sodium polyacrylate and sodium polybutenoate, preferably sodium polybutenoate;

[0021] When the impurity is silicon, the precipitant is an inorganic calcium salt that can react with silicon to form a precipitate, including one or a combination of calcium aluminate, calcium bicarbonate and calcium hydroxide, preferably calcium aluminate.

[0022] In step (3) of the preparation method described above, the sulfuric acid is concentrated sulfuric acid or dilute sulfuric acid. For sulfuric acid with a concentration greater than 10%, it needs to be added slowly dropwise according to the calculated amount when neutralizing with sodium aluminate, accompanied by strong stirring and air cooling, so as to dissipate the generated heat in time and keep the temperature in the reactor constant; otherwise, it will affect the electronegativity of boehmite. As a specific embodiment of the preparation method described above, in step (3), the reaction temperature is 60-90℃, and the final pH value is 8.0-9.0.

[0023] As a specific embodiment of the preparation method described above in this invention, in step (3), sulfuric acid and sodium aluminate purification solution are added dropwise in parallel and mixed to react and obtain a suspension containing a large specific surface area of ​​boehmite.

[0024] As a specific embodiment of the preparation method described above in this invention, in step (4), the hydroxycarboxylate salt refers to a compound that contains both hydroxyl and carboxyl groups, including one or a combination of sodium citrate, sodium triacetate and sodium ethylenediaminetetraacetate.

[0025] As a specific embodiment of the preparation method described above in this invention, in step (4), under the conditions of pH value of 9.5-10.5 and temperature of 60-90℃, a suspension containing boehmite and a hydroxycarboxylate are mixed.

[0026] In step (4) of the preparation method described above in this invention, the pH value of the suspension containing boehmite can be adjusted to 9.5-10.5 first, and then hydroxycarboxylate can be added to it.

[0027] This invention does not specify the exact method for adjusting the pH of the suspension containing boehmite to 9.5-10.5. Adjustments can be made according to actual needs, as long as the objective of this invention is achieved. For example, in some embodiments of this invention, the pH can be adjusted to 9.5-10.5 by adding the sodium aluminate purification solution obtained in step (2) to the suspension containing boehmite.

[0028] In step (5) of the preparation method described above, under suitable temperature and pH conditions, positively charged aluminum ions and negatively charged boehmite suspension are mixed, which can further increase the growth of boehmite sol particles and increase pore volume, thereby obtaining high specific surface area (high specific surface area) macroporous boehmite.

[0029] As a specific embodiment of the preparation method described above in this invention, in step (5), under the condition of a temperature of 60-90°C, positively charged aluminum ions and negatively charged boehmite suspension are mixed until the pH value is 7.0-9.0.

[0030] As a specific embodiment of the preparation method described above in this invention, in step (5), positively charged aluminum ions are mixed with negatively charged boehmite suspension in the form of aluminum salts, wherein the aluminum salts include one or a combination of aluminum sulfate, aluminum chloride and aluminum nitrate.

[0031] The method for preparing high-specific-surface-area, macroporous pseudoboehmite provided by this invention increases the content of the target metal element by removing aluminum from the ore, thus restoring its smelting value. Simultaneously, by controlling the aluminum removal conditions, such as temperature and pH, it is made into high-specific-surface-area, macroporous pseudoboehmite. Using this high-specific-surface-area, macroporous pseudoboehmite as a raw material for hydrogenation catalysts can reduce the production cost of hydrogenation catalysts and improve their market competitiveness.

[0032] On the other hand, the present invention also provides a high specific surface area macroporous volume pseudoboehmite, wherein the high specific surface area macroporous volume pseudoboehmite is prepared by the above-described preparation method of high specific surface area macroporous volume pseudoboehmite.

[0033] As a specific embodiment of the pseudoboehmite described above in this invention, the specific surface area of ​​the pseudoboehmite is ≥400 m². 2 / g, pore volume ≥1.0cm 3 / g, with a pore size ≥7.0nm and a concentrated pore size distribution, with 5-15nm pores accounting for ≥60%, and no macropores with a pore size greater than 50nm.

[0034] In another aspect, the present invention also provides a hydrogenation catalyst, wherein the hydrogenation catalyst comprises the high specific surface area and large pore volume pseudoboehmite described above.

[0035] The hydrogenation catalyst containing the high specific surface area and large pore volume pseudoboehmite provided by the present invention has low cost, high specific surface area and large pore volume, higher catalytic activity, greater impurity capacity, and stronger market competitiveness.

[0036] This invention does not impose specific requirements on the preparation method of the hydrogenation catalyst described above, and can make reasonable adjustments according to the actual needs of on-site operations.

[0037] Compared with the prior art, the beneficial technical effects achieved by the present invention include:

[0038] First, the method for preparing pseudoboehmite provided by this invention uses associated aluminum ore produced as a byproduct of the metallurgical process as raw material, which is a form of industrial waste resource reuse and has a low cost. Compared with similar macroporous pseudoboehmite with the same indicators and performance prepared by other existing methods, the production cost of this invention is reduced by more than 90%, which can guide the hydrogenation catalyst industry to reduce production costs and improve the market competitiveness of hydrogenation catalysts.

[0039] Secondly, the macroporous boehmite prepared by this invention has a larger specific surface area because: sulfuric acid is highly acidic, and when added to sodium aluminate solution, it can rapidly and massively form boehmite nuclei in a short time, significantly increasing the specific surface area of ​​the boehmite; while traditional macroporous boehmite is prepared using sodium aluminate and aluminum sulfate, which has low acidity and slow nucleation rate, resulting in a relatively small specific surface area of ​​the prepared boehmite.

[0040] Third, the macroporous boehmite prepared by this invention has a large pore volume because: the carboxyl group in the hydroxycarboxylate can be embedded into the boehmite core, and the hydroxyl group is free on the outer surface of the boehmite core, making the boehmite negatively charged, which interacts with the positively charged Al. 3+ After mixing, Al 3+ The formation of pseudoboehmite continues outside the pseudoboehmite core, which helps the pseudoboehmite colloidal particles grow rapidly, allowing the pseudoboehmite to accumulate and form a larger pore volume.

[0041] In summary, the pseudoboehmite prepared by this invention is inexpensive, has good physical properties, and possesses a large specific surface area and large pore volume, with a specific surface area ≥ 400 m². 2 / g, pore volume ≥1.0cm 3 / g, with a pore size ≥7.0nm and a concentrated pore size distribution, with 5-15nm pores accounting for ≥60%, no large pores with a pore size greater than 50nm, and the pore volume, pore size and pore distribution can be adjusted as needed to meet the application requirements of various catalyst industries. Detailed Implementation

[0042] It should be noted that the term "comprising" and any variations thereof in the specification and claims of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such processes, methods, products, or devices.

[0043] The "range" disclosed in this invention is given in the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges defined in this way are composable, meaning that any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for specific parameters, it is also expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if the listed minimum range values ​​are 1 and 2, and the listed maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0044] In this invention, unless otherwise specified, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this invention, and "0-5" is simply a shortened representation of these numerical combinations.

[0045] In this invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in this invention can be combined with each other to form new technical solutions.

[0046] In this invention, unless otherwise specified, all technical features and preferred features mentioned in this invention can be combined with each other to form new technical solutions.

[0047] In this invention, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the appendices and embodiments. The embodiments described below are some, but not all, embodiments of this invention, and are only used to illustrate the invention, and should not be considered as limiting the scope of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0049] Example 1

[0050] This embodiment uses associated bauxite produced during chromium metallurgy as raw material to prepare high specific surface area and large pore volume pseudoboehmite, including the following steps:

[0051] Step (1): Take 1000g of chromite associated with aluminum ore, add 350g of NaOH and 1000mL of pure water, boil and stir at 110℃ to dissolve, leach aluminum hydroxide, and filter the mixture using a plate and frame filter press to obtain enriched residue and leachate, which is sodium aluminate solution containing impurities.

[0052] Of which, based on the total weight of the associated aluminum ore of the chromite as 100%, its main components are Al2O3 (35%), CrO3 (2%), V2O5 (1%), SiO2 (1%), Fe2O3 (0.5%), H2O (60%) and others 0.5%;

[0053] Step (2): Add 10g of sodium polyacrylate precipitant to the leachate to remove Fe2O3, and then add 20g of calcium aluminate to remove SiO2. Then use separation equipment such as plate and frame filter press to separate the undissolved impurities in the leachate to obtain sodium aluminate purified solution.

[0054] Step (3): Slowly add concentrated H2SO4 (98wt%) and sodium aluminate purification solution in a high-strength stirring device, while keeping the temperature constant at 60℃ and the pH value constant at 8.0. After the reaction is completed, a suspension containing boehmite is obtained.

[0055] Step (4): Keep the temperature constant at 60℃, continue to add sodium aluminate purification solution to the suspension containing boehmite, adjust the pH to 10.0, and then add 20g of sodium ethylenediaminetetraacetate to obtain a negatively charged boehmite suspension.

[0056] Step (5): Keep the temperature constant at 60℃, add Al2(SO4)3 solution dropwise to the negatively charged pseudoboehmite suspension, and stop adding Al2(SO4)3 solution when the pH value is 8.0, and let it stand for 30 minutes to age.

[0057] Step (6): Add ammonium carbonate to the solution obtained in step (5) so that its anions can convert Na+ into sodium carbonate. + and SO4 2- After displacement, the system is rinsed with a large amount of deionized water to remove Na+. + and SO4 2- The content was reduced to the value required by the index;

[0058] Step (7): The product obtained after washing in step (6) is subjected to high-temperature rapid drying, wherein the drying temperature is 200℃ and the drying time is 1.5h. After drying, a high specific surface area and large pore volume pseudoboehmite is obtained, which is denoted as sample A.

[0059] Example 2

[0060] This embodiment uses associated bauxite produced during rare earth metallurgy as raw material to prepare high specific surface area and large pore volume pseudoboehmite, including the following steps:

[0061] Step (1): Take 1000g of rare earth associated aluminum ore, add 350g of NaOH and 1000mL of pure water to it, boil and stir at 110℃ to dissolve, leach aluminum hydroxide, and filter the mixture using a plate and frame filter press to obtain enriched residue and leachate, which is sodium aluminate solution containing impurities.

[0062] Of which, based on the total weight of the rare earth ore associated with aluminum ore as 100%, its main components are Al2O3 (35%), ReO (2%), V2O5 (1%), SiO2 (1%), Fe2O3 (0.5%), H2O (60%) and others 0.5%;

[0063] Step (2): Add 10g of sodium polyacrylate precipitant to the leachate to remove Fe2O3, and then add 20g of calcium aluminate to remove SiO2. Then use separation equipment such as plate and frame filter press to separate the undissolved impurities in the leachate to obtain sodium aluminate purified solution.

[0064] Step (3): Slowly add concentrated H2SO4 (98wt%) and sodium aluminate purification solution in a high-strength stirring device, while keeping the temperature constant at 60℃ and the pH value constant at 8.0. After the reaction is completed, a suspension containing boehmite is obtained.

[0065] Step (4): Keep the temperature constant at 60℃, continue to add sodium aluminate purification solution to the suspension containing boehmite to adjust the pH value of the suspension containing boehmite to 10.0, and then add 20g of sodium citrate to obtain a negatively charged boehmite suspension.

[0066] Step (5): Keep the temperature constant at 60℃, add Al2(SO4)3 solution dropwise to the negatively charged pseudoboehmite suspension, and stop adding Al2(SO4)3 solution when the pH value is 8.0, and let it stand for 30 minutes to age.

[0067] Step (6): Add ammonium bicarbonate to the solution obtained in step (5) so that its anions can convert Na+ into sodium bicarbonate. + and SO4 2- After displacement, the system is rinsed with a large amount of deionized water to remove Na+. + and SO4 2- The content was reduced to the value required by the index;

[0068] Step (7): The product obtained after washing in step (6) is subjected to high-temperature rapid drying, wherein the drying temperature is 150°C and the drying time is 3.5h. After drying, a high specific surface area and large pore volume pseudoboehmite is obtained, which is denoted as sample B.

[0069] Example 3

[0070] This embodiment uses associated bauxite produced during titanium metallurgy as raw material to prepare high specific surface area and large pore volume pseudoboehmite, including the following steps:

[0071] Step (1): Take 1000g of titanium ore associated with aluminum ore, add 350g of NaOH and 1000mL of pure water to it, boil and stir at 110℃ to dissolve, leach aluminum hydroxide, and filter the mixture using a plate and frame filter press to obtain enriched residue and leachate, which is sodium aluminate solution containing impurities.

[0072] Of which, based on the total weight of the associated aluminum ore of the titanium mine as 100%, its main components are Al2O3 (35%), TiO2 (2%), V2O5 (1%), SiO2 (1%), Fe2O3 (0.5%), H2O (60%) and others 0.5%;

[0073] Step (2): Add 10g of sodium polyacrylate precipitant to the leachate to remove Fe2O3, and then add 20g of calcium aluminate to remove SiO2. Then use separation equipment such as plate and frame filter press to separate the undissolved impurities in the leachate to obtain sodium aluminate purified solution.

[0074] Step (3): Slowly add concentrated H2SO4 (98wt%) and sodium aluminate purification solution in a high-strength stirring device, while keeping the temperature constant at 80℃ and the pH value constant at 8.5. After the reaction is completed, a suspension containing boehmite is obtained.

[0075] Step (4): Keep the temperature constant at 80℃, continue to add sodium aluminate purification solution to the suspension containing boehmite to adjust the pH value of the suspension containing boehmite to 9.5, and then add 20g of sodium triacetate to obtain a negatively charged boehmite suspension.

[0076] Step (5): Keep the temperature constant at 80℃, add Al2(SO4)3 solution dropwise to the negatively charged pseudoboehmite suspension, and stop adding Al2(SO4)3 solution when the pH value is 7.0, and let it stand for 30 minutes to age.

[0077] Step (6): Add sodium bicarbonate to the solution obtained in step (5) so that its anions can convert Na+ into sodium bicarbonate. + and SO4 2- After displacement, the system is rinsed with a large amount of deionized water to remove Na+. + and SO4 2- The content was reduced to the value required by the index;

[0078] Step (7): The product obtained after washing in step (6) is subjected to high-temperature rapid drying, wherein the drying temperature is 100℃ and the drying time is 6h. After drying, a high specific surface area and large pore volume pseudoboehmite is obtained, which is denoted as sample C.

[0079] Example 4

[0080] This embodiment uses associated bauxite produced during chromium metallurgy as raw material to prepare high specific surface area and large pore volume pseudoboehmite, including the following steps:

[0081] Step (1): Take 1000g of chromite associated with aluminum ore, add 350g of NaOH and 1000mL of pure water, boil and stir at 110℃ to dissolve, leach aluminum hydroxide, and filter the mixture using a plate and frame filter press to obtain enriched residue and leachate, which is sodium aluminate solution containing impurities.

[0082] Of which, based on the total weight of the associated aluminum ore of the chromite as 100%, its main components are Al2O3 (35%), CrO3 (2%), V2O5 (1%), SiO2 (1%), Fe2O3 (0.5%), H2O (60%) and others 0.5%;

[0083] Step (2): Add 10g of sodium polyacrylate precipitant to the leachate to remove Fe2O3, and then add 20g of calcium aluminate to remove SiO2. Then use separation equipment such as plate and frame filter press to separate the undissolved impurities in the leachate to obtain sodium aluminate purified solution.

[0084] Step (3): Slowly add concentrated H2SO4 (98wt%) and sodium aluminate purification solution in a high-strength stirring device, while keeping the temperature constant at 90℃ and the pH value constant at 9.0. After the reaction is completed, a suspension containing boehmite is obtained.

[0085] Step (4): Keep the temperature constant at 90℃, continue to add sodium aluminate purification solution to the suspension containing boehmite, adjust the pH to 10.5, and then add 20g of sodium ethylenediaminetetraacetate to the suspension containing boehmite to obtain a negatively charged boehmite suspension.

[0086] Step (5): Keep the temperature constant at 90℃, add AlCl3 solution dropwise to the negatively charged pseudoboehmite suspension, and stop adding AlCl3 solution when the pH value is 9.0. Let it stand for 30 minutes to age.

[0087] Step (6): Add sodium sulfide to the solution obtained in step (5) so that its anions can react with Na+. + and SO4 2- After displacement, the system is rinsed with a large amount of deionized water to remove Na+. + and SO4 2- The content was reduced to the value required by the index;

[0088] Step (7): The product obtained after washing in step (6) is subjected to high-temperature rapid drying, wherein the drying temperature is 200℃ and the drying time is 1.5h. After drying, a high specific surface area and large pore volume pseudoboehmite is obtained, which is denoted as sample D.

[0089] Comparative Example 1

[0090] This comparative example uses associated bauxite produced during chromium metallurgy as raw material to prepare pseudoboehmite, including the following steps:

[0091] Step (1): Take 1000g of chromite associated with aluminum ore, add 350g of NaOH and 1000mL of pure water, boil and stir at 110℃ to dissolve, leach aluminum hydroxide, and filter the mixture using a plate and frame filter press to obtain enriched residue and leachate, which is sodium aluminate solution containing impurities.

[0092] Of which, based on the total weight of the associated aluminum ore of the chromite as 100%, its main components are Al2O3 (35%), CrO3 (2%), V2O5 (1%), SiO2 (1%), Fe2O3 (0.5%), H2O (60%) and others 0.5%;

[0093] Step (2): Add 10g of sodium polyacrylate precipitant to the leachate to remove Fe2O3, and then add 20g of calcium aluminate to remove SiO2. Then use separation equipment such as plate and frame filter press to separate the undissolved impurities in the leachate to obtain sodium aluminate purified solution.

[0094] Step (3): Slowly add Al2(SO4)3 and sodium aluminate purification solution in a high-strength stirring device, while keeping the temperature constant at 60°C and the pH value constant at 8.0. After the reaction is completed, a suspension containing boehmite is obtained.

[0095] Step (4): Keep the temperature constant at 60℃, continue to add sodium aluminate purification solution to the suspension containing boehmite, adjust the pH to 10.0, and then add 20g of sodium ethylenediaminetetraacetate to the suspension containing boehmite to form a negatively charged boehmite suspension.

[0096] Step (5): Keep the temperature constant at 60℃, add Al2(SO4)3 solution dropwise to the negatively charged pseudoboehmite suspension, and stop adding Al2(SO4)3 solution when the pH value is 8.0, and let it stand for 30 minutes to age.

[0097] Step (6): Add ammonium carbonate to the solution obtained in step (5) so that its anions can convert Na+ into sodium carbonate. + and SO4 2- After displacement, the system is rinsed with a large amount of deionized water to remove Na+. + and SO4 2- The content was reduced to the value required by the index;

[0098] Step (7): The product obtained after washing in step (6) is subjected to high-temperature rapid drying, wherein the drying temperature is 200℃ and the drying time is 1.5h. After drying, pseudoboehmite is obtained, which is denoted as sample E.

[0099] Comparative Example 2

[0100] This comparative example uses associated bauxite produced during chromium metallurgy as raw material to prepare pseudoboehmite, including the following steps:

[0101] Step (1): Take 1000g of chromite associated with aluminum ore, add 350g of NaOH and 1000mL of pure water, boil and stir at 110℃ to dissolve, leach aluminum hydroxide, and filter the mixture using a plate and frame filter press to obtain enriched residue and leachate, which is sodium aluminate solution containing impurities.

[0102] Of which, based on the total weight of the associated aluminum ore of the chromite as 100%, its main components are Al2O3 (35%), CrO3 (2%), V2O5 (1%), SiO2 (1%), Fe2O3 (0.5%), H2O (60%) and others 0.5%;

[0103] Step (2): Add 10g of sodium polyacrylate precipitant to the leachate to remove Fe2O3, and then add 20g of calcium aluminate to remove SiO2. Then use separation equipment such as plate and frame filter press to separate the undissolved impurities in the leachate to obtain sodium aluminate purified solution.

[0104] Step (3): Slowly add concentrated H2SO4 (98wt%) and sodium aluminate purification solution in a high-strength stirring device, while keeping the temperature constant at 60℃ and the pH value constant at 8.0. After the reaction is completed, a suspension containing boehmite is obtained.

[0105] Step (4): Keep the temperature constant at 60℃ and continue to add sodium aluminate purification solution to the suspension containing boehmite to adjust the pH to 10.0, so as to obtain a neutral boehmite suspension.

[0106] Step (5): Keep the temperature constant at 60℃, add Al2(SO4)3 solution dropwise to the above neutral pseudoboehmite suspension, and stop adding Al2(SO4)3 solution when the pH value is 8.0, and let it stand for 30 minutes to age.

[0107] Step (6): Add ammonium carbonate to the solution obtained in step (5) so that its anions can convert Na+ into sodium carbonate. + and SO4 2- After displacement, the system is rinsed with a large amount of deionized water to remove Na+. + and SO4 2- The content was reduced to the value required by the index;

[0108] Step (7): The product obtained after washing in step (6) is subjected to high-temperature rapid drying, wherein the drying temperature is 200℃ and the drying time is 1.5h. After drying, pseudoboehmite is obtained, which is denoted as sample F.

[0109] Test Example 1

[0110] In this test example, conventional methods were used to test and analyze the physicochemical properties of the pseudoboehmite provided in Examples 1-4 and Comparative Examples 1-2 of this invention, including specific surface area, pore volume, pore size, SiO2 content, Fe2O3 content, Na2O content, and Al2O3 content. The experimental results are shown in Table 1 below.

[0111] Table 1

[0112] As can be seen from Table 1 above, the specific surface area of ​​the pseudoboehmite provided in Examples 1-4 of this invention is ≥400 m². 2 / g, pore volume ≥1.0cm 3 / g indicates that they all have high specific surface area and large pore volume.

[0113] Comparing the experimental results of Example 1 and Comparative Example 1 in Table 1, it can be seen that the Al2O3 purity of sample E prepared in Comparative Example 1 is lower and the specific surface area is smaller. Compared with sample E provided in Comparative Example 1, the specific surface area of ​​the boehmite sample obtained in this embodiment of the invention can be increased by at least 34.1%. The reason is that when preparing boehmite suspension with non-strong acid solution, it is easy to introduce other impurities, resulting in lower Al2O3 purity. In addition, when non-strong acid solution is added to sodium aluminate solution, the number of boehmite colloidal nuclei formed is less, which is not conducive to improving the specific surface area of ​​boehmite.

[0114] Comparing the experimental results of Example 1 and Comparative Example 2 in Table 1, it can be seen that although the specific surface area of ​​sample F prepared in Comparative Example 2 is larger, its pore volume and probable pore size are smaller. Compared with sample F provided by Comparative Example 2, the pore volume of the pseudoboehmite sample obtained in this embodiment can be increased by at least 18.7%, and the probable pore size can be increased by at least 81.2%. The reason is that Comparative Example 2 did not add hydroxycarboxylate, so it could not form negatively charged pseudoboehmite, and therefore could not allow the negatively charged pseudoboehmite and positively charged Al to pass through. 3+ The interaction between the two promotes the growth of pseudoboehmite grains, resulting in smaller pore volume and probable pore size of the pseudoboehmite prepared from it.

[0115] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical inventions, and technical inventions in this invention can be freely combined and used.

Claims

1. A method for preparing high specific surface area and large pore volume pseudoboehmite, characterized in that, The preparation method includes: Step (1): Mix excess NaOH solution with associated aluminum ore and boil to leach aluminum hydroxide, and obtain sodium aluminate solution containing impurities; Step (2): Mix the sodium aluminate solution containing impurities with a precipitant to precipitate the impurities and obtain sodium aluminate purified solution; Step (3): After mixing sulfuric acid and sodium aluminate purification solution, react to obtain a suspension containing boehmite; Step (4): Mix the suspension containing boehmite with hydroxycarboxylate to make boehmite negatively charged, thus obtaining a negatively charged boehmite suspension. Step (5): Mix positively charged aluminum ions and negatively charged boehmite suspension to obtain high specific surface area and large pore volume boehmite.

2. The preparation method according to claim 1, characterized in that, The preparation method further includes step (6): mixing the solution obtained in step (5) with the desorbent and washing the resulting mixture.

3. The preparation method according to claim 2, characterized in that, The desorbent includes one or a combination of several of ammonium carbonate, ammonium bicarbonate, sodium bicarbonate, and sodium sulfide.

4. The preparation method according to claim 2, characterized in that, The preparation method further includes step (7): the solution washed in step (6) is subjected to high temperature and rapid drying to obtain the high specific surface area macroporous volume pseudoboehmite.

5. The preparation method according to any one of claims 1-4, characterized in that, In step (1), according to the caustic ratio α k Mix NaOH solution with associated bauxite and boil to a concentration of 1.5-3.

0.

6. The preparation method according to any one of claims 1-4, characterized in that, In step (2), when the impurity is iron, the precipitant is an organic oligomer flocculant, including one or a combination of sodium polyvinyl acetate, sodium polyacrylate and sodium polybutenoate; When the impurity is silicon, the precipitant is an inorganic calcium salt, including one or a combination of calcium aluminate, calcium bicarbonate and calcium hydroxide.

7. The preparation method according to any one of claims 1-4, characterized in that, In step (3), the reaction temperature is 60-90℃ and the final pH value is 8.0-9.

0.

8. The preparation method according to any one of claims 1-4, characterized in that, In step (4), the hydroxycarboxylic acid salt includes one or a combination of sodium citrate, sodium triacetate and sodium ethylenediaminetetraacetate.

9. The preparation method according to any one of claims 1-4, characterized in that, In step (4), the suspension containing boehmite and hydroxycarboxylate are mixed under the conditions of pH 9.5-10.5 and temperature 60-90℃.

10. The preparation method according to any one of claims 1-4, characterized in that, In step (5), at a temperature of 60-90℃, positively charged aluminum ions and negatively charged boehmite suspension are mixed until the pH value is 7.0-9.

0.

11. The preparation method according to any one of claims 1-4, characterized in that, In step (5), positively charged aluminum ions are mixed with negatively charged boehmite suspension in the form of aluminum salts, wherein the aluminum salts include one or a combination of aluminum sulfate, aluminum chloride and aluminum nitrate.

12. A high specific surface area and large pore volume pseudoboehmite, characterized in that, The high specific surface area macroporous volume pseudoboehmite is prepared by the preparation method of the high specific surface area macroporous volume pseudoboehmite according to any one of claims 1-11.

13. The pseudoboehmite according to claim 12, characterized in that, The specific surface area of ​​the pseudoboehmite is ≥400m². 2 / g, pore volume ≥1.0cm 3 / g, with a pore size ≥7.0nm and a concentrated pore size distribution, with 5-15nm pores accounting for ≥60%, and no macropores with a pore size greater than 50nm.

14. A hydrogenation catalyst, characterized in that, The hydrogenation catalyst comprises the high specific surface area, large pore volume, pseudoboehmite as described in claim 12 or 13.

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