A phosphorus-aluminum sol with high polymerization degree and a preparation method thereof
By controlling the particle size and degree of polymerization of aluminum phosphate sol through a low-cost preparation method, the problems of high cost and low degree of polymerization in the prior art are solved, and efficient bonding performance and improved catalyst activity are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2023-04-27
- Publication Date
- 2026-06-16
AI Technical Summary
The preparation cost of phosphorus aluminum sol in the existing technology is high and the degree of polymerization is not high, which affects the bonding performance and catalyst activity.
Using low-cost aluminum salts and phosphates as raw materials, phosphorus-aluminum sol is prepared by reacting under specific temperature and stirring conditions. The particle size is controlled between 10 and 30 nm, and the phosphorus-aluminum ratio (QPO2/QPO0) is increased to enhance the degree of polymerization.
To reduce production costs, improve the binding performance and catalyst activity of phosphorus aluminum sol, reduce clogging of molecular sieve channels, and enhance the catalyst's wear resistance and selectivity.
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Abstract
Description
Technical Field
[0001] This invention relates to a phosphorus aluminum sol binder and its preparation method. Background Technology
[0002] Phosphorus aluminum sol has been widely used in catalysts, building materials, refractories, and inorganic coatings. It is not only a commonly used binder in refractory materials but also an important component in inorganic coating formulations. It can also be used in siliceous, high-alumina, magnesia, silicon carbide, and oxide concrete. In the preparation of certain catalytic cracking catalysts, it is used as a matrix, acting not only as a binder but also improving the catalyst's reactivity.
[0003] CN1070384A provides a method for preparing phosphorus-containing aluminum sol: adding orthophosphoric acid or aluminum dihydrogen phosphate to aluminum sol, followed by high-temperature depolymerization and concentration steps to obtain phosphorus-containing aluminum sol. CN1070385A provides a method for preparing phosphorus-containing aluminum sol by reacting a mixture of metallic aluminum, hydrochloric acid (or aluminum chloride), and orthophosphoric acid (or aluminum dihydrogen phosphate) under certain conditions, followed by high-temperature depolymerization and concentration. Both methods are not only costly but also complex in their preparation processes. The resulting product is a phosphorus-modified aluminum sol with a low phosphorus content.
[0004] CN1417296A discloses a chlorine-free phosphorus-containing aluminum sol that can be used in petroleum hydrocarbon cracking catalysts, and its preparation method. The phosphorus-containing aluminum sol contains 2-10% by weight Al and 5-20% by weight P, and is chlorine-free, with a P / Al weight ratio of 1.2-6 and a pH of 1.0-2.5. The preparation method involves dispersing an acid-soluble aluminum hydroxide or aluminum oxide with decationized water to form a slurry with a solid content of 15-35% by weight. While stirring, concentrated phosphoric acid is added to the slurry at a P / Al weight ratio of 1.2-6. The mixture is then heated to 65-95°C and reacted at this temperature for 15-90 minutes until it becomes a transparent colloid. This chlorine-free phosphorus-containing aluminum sol can be mixed with conventional chlorine-containing aluminum sols. However, this method for preparing aluminum phosphate sol is prone to reactant solidification due to fluctuations in reaction conditions during the preparation process. The resulting aluminum phosphate sol has a high content of free phosphate and a low degree of polymerization. Furthermore, the cracking catalyst prepared using the aluminum phosphate sol prepared by this method has low activity.
[0005] CN102847547B discloses an inorganic binder containing a phosphorus-aluminum compound and its preparation method. The method involves dispersing acid-soluble aluminum hydroxide and / or alumina, along with clay and decationized water, into a slurry with a solid content of 15-45% by weight. Concentrated phosphoric acid is then added to the slurry under stirring at a P / Al weight ratio of 1-6, followed by reaction at 50-99°C for 15-90 minutes. This preparation method avoids binder solidification caused by localized, intense, and exothermic reactions due to uneven material distribution. The resulting binder improves the wear resistance, activity, and selectivity of FCC catalysts. However, the binder obtained by this method contains clay and has a low degree of polymerization.
[0006] CN115215311A provides an aluminum phosphate sol, its preparation method and application, and a catalytic cracking catalyst and its preparation method. The aluminum phosphate sol particles have an outer layer structure and an internal structure within the outer layer. The preparation method includes (1) mixing an aluminum source with water to form an aluminum source slurry; (2) making the aluminum source slurry obtained in step (1) into a first contact with a first phosphoric acid to obtain a second slurry; and (3) making the second slurry obtained in step (2) into a second contact with a second phosphoric acid, and then heating the reaction. This aluminum phosphate sol has good bonding properties and stability, and can be used as a binder for catalytic cracking catalysts. However, the degree of polymerization of this aluminum phosphate sol is not high enough, the free phosphate group is relatively high, and the bonding strength is still not high.
[0007] In the existing technology, the preparation of phosphoric acid aluminum sol using phosphoric acid and alumina has two drawbacks: firstly, the cost is relatively high, and secondly, it is prone to react with other alumina colloids in the catalyst, affecting the bonding performance. Summary of the Invention
[0008] The technical problem to be solved by the present invention is to provide a high degree of polymerization of aluminum phosphate sol binder and its preparation method, wherein the aluminum phosphate sol has better adhesion.
[0009] This invention provides a phosphorus aluminum sol (hereinafter referred to as phosphorus aluminum sol), which contains 3-15 wt% Al2O3, 15-40 wt% P2O5, has a P / Al weight ratio of 1.6-6, a pH value of 0.5-2.5, and QPO. 2 / QP0 0 =1.5~5, the particle size of the phosphorus aluminum sol is mainly concentrated between 10~30nm.
[0010] Phosphoaluminum sol 31 In p-NMR spectroscopy, the area of the resonance signal peak with a chemical shift of 12 ± 2 ppm is defined as QP0. 2 The peak area of the resonance signal with a chemical shift of 0 ± 2 ppm is defined as QP0. 0 At the same phosphorus-aluminum ratio, QP0 2 / QP0 0A higher value indicates a higher degree of polymerization.
[0011] The particle size of the aluminum phosphate sol is mainly concentrated between 10 and 30 nm, which means that the aggregation degree of the aluminum phosphate sol is >85%. The aggregation degree refers to the proportion of particles with a particle size of 10 to 30 nm; the particle size (or particle size) is measured by transmission electron microscopy and is the maximum size of the particle projection, and the average particle size is the arithmetic mean of the particle sizes.
[0012] The present invention further provides a method for preparing the aforementioned aluminum phosphate sol, comprising:
[0013] An alumina precursor solution is prepared by slurry dispersing an aluminum salt source, decationized water, and stabilizer into a solution with a solid content of 5-40% by weight at a temperature of 50℃-95℃ and under stirring conditions. Phosphate is then added to this solution at a temperature of 25℃-70℃ and under stirring conditions, and the reaction continues until a transparent colloid is formed. For example, the reaction is carried out by stirring for 10-60 minutes after the addition of phosphate.
[0014] The deionized water, also known as deionized water, is well known to those skilled in the art. The pH value of the deionized water is preferably 2.8–3.2, and the sodium oxide content is preferably <5 ppm.
[0015] The aluminum phosphate sol provided by this invention has a higher QPO at the same aluminum phosphate ratio. 2 / QP0 0 Compared to other materials, the degree of polymerization is higher. The aluminum phosphate sol provided by this invention has a certain particle size while having a high degree of polymerization, resulting in good bonding performance, reducing clogging of molecular sieve channels, and improving catalyst activity.
[0016] The aluminum phosphate sol provided by this invention can polymerize at high temperatures to form a substance with a high melting point and high binding strength, which can improve the strength and high-temperature resistance of materials, and improve wear resistance. This aluminum phosphate sol can be used as a binder in catalyst preparation, as a binder for refractory materials, and as an additive in coatings. For example, the aluminum phosphate sol provided by this invention, due to its appropriate particle size and high degree of polymerization, can be used in the preparation of catalysts containing molecular sieves. For example, the aluminum phosphate sol binder used in the preparation of FCC catalysts can reduce pore blockage of molecular sieves, improve catalyst activity, and increase catalyst strength. For example, it can improve the wear resistance (wear strength) of FCC catalysts, increase cracking activity, and also improve the selectivity of FCC catalysts, for example, in some cases, it can improve the selectivity of gasoline, propylene, or butene.
[0017] The method for preparing aluminum phosphate sol provided by the present invention has at least one of the following advantages, and preferably has one or more of these advantages:
[0018] 1. Using low-cost aluminum salts and phosphates as raw materials can reduce production costs.
[0019] 2. It can prevent the formation of sediment and extend the storage time of aluminum phosphate gel.
[0020] 3. It can shorten the synthesis time.
[0021] 4. The prepared aluminum phosphate sol can have a higher QP0 at the same aluminum phosphate ratio. 2 / QP0 0 The free phosphate groups are relatively few, while the polymerized phosphate groups are more numerous. This can reduce the reaction between aluminum phosphate sol and other binders, and at the same time reduce the destructive effect on non-framework Al and framework Al in the molecular sieve.
[0022] 5. The obtained phosphorus aluminum sol has uniform particle size, appropriate surface hydroxyl groups, and high aggregation degree, resulting in higher activity and better matching with shape-selective molecular sieves, thus improving the selectivity of low-carbon olefins in FCC.
[0023] 6. The obtained aluminum phosphate sol has good binding properties and can improve the strength of the catalyst when used in catalyst preparation. Attached Figure Description
[0024] Figure 1 The aluminum phosphate sols obtained in Example 1 and Comparative Example 1 31 P nuclear magnetic resonance spectrum.
[0025] Figure 2 This is an electron microscope image of the morphology obtained in Example 1. Detailed Implementation
[0026] The aluminum phosphate sol provided by the present invention contains 3-15% by weight, for example, 3-12% by weight of Al2O3.
[0027] The phosphorus aluminum sol provided by the present invention contains 15-40% by weight, for example 15-32% by weight, of P2O5.
[0028] The aluminum phosphate sol provided according to the present invention contains 0.1 to 10% by weight of a stabilizer, for example, 0.5 to 5% by weight or 2 to 4% by weight of a stabilizer. The stabilizer is a weakly acidic organic acid, for example, the stabilizer is selected from at least one of glycolic acid, oxalic acid, acetic acid, malonic acid, malic acid, tartaric acid, succinic acid, adipic acid, maleic acid, itaconic acid, citric acid, etc., and the stabilizer is preferably oxalic acid, acetic acid, or citric acid.
[0029] The phosphorus aluminum sol provided by this invention has a P / Al weight ratio of 1.6 to 6, for example, 1.6 to 5.6, for example, 2, 3, 4 or 5.
[0030] The phosphoaluminum sol provided by the present invention preferably has a pH value of 0.5 to 2.5, for example, 0.8 to 1.9.
[0031] The phosphorus aluminum sol provided by this invention is QP0. 2 / QP0 0 =1.5~5, for example, 1.5~4 or 1.5~3.3 or 2~5.
[0032] The phosphorus aluminum sol provided by this invention has a particle size mainly concentrated between 10 and 30 nm, and a particle aggregation degree greater than 85%, for example, 85% to 95%.
[0033] The average particle size (also known as particle diameter) of the phosphate aluminum sol is 10-30 nm, for example, 15-28 nm.
[0034] The aluminum phosphate sol contains a balanced amount of water, preferably 10-30% by weight.
[0035] In one embodiment, the aluminum phosphate sol contains cations from phosphates, such as ammonium ions, in a content of, for example, 5-15% by weight.
[0036] In one embodiment, the phosphorus aluminum sol contains inorganic acid radicals from an aluminum salt source, such as one or more of sulfate, chloride, and nitrate, and the content of the inorganic acid radicals is, for example, 10-50% by weight.
[0037] Preferably, the temperature for dispersing the aluminum salt source, decationized water, and stabilizer is 60℃~90℃; and the temperature for adding phosphate under stirring conditions is 30-55℃.
[0038] Preferably, the method for preparing the aluminum phosphate sol includes: dispersing an aluminum salt source, decationized water, and a stabilizer into a solution with a solid content of 5-40% by weight, stirring for at least 5 minutes, for example, 10-50 minutes, to hydrolyze the aluminum salt source; then reacting for a period of time under controlled conditions of 25°C-70°C and stirring to form a sol and inhibit precipitation.
[0039] The aluminum phosphate sol prepared by the method of the present invention contains 0.1-10% by weight of a stabilizer. The stabilizer is an organic acid with weak ionization properties, typically a weakly acidic organic acid. Preferably, the molar ratio of the organic acid anion to aluminum in the stabilizer is 0.05-0.5.
[0040] The method for preparing aluminum phosphate sol provided by the present invention can be one or more of aluminum nitrate, aluminum sulfate, and aluminum chloride, for example, one or more of aluminum nitrate, aluminum sulfate, and aluminum chloride.
[0041] The phosphate is diamine hydrogen phosphate and / or ammonium dihydrogen phosphate. The phosphate can be added by adding a phosphate solution or by adding a solid phosphate.
[0042] The method for preparing aluminum phosphate sol provided by the present invention preferably has a pH value of 0.5 to 3.0, for example, 0.6 to 2 or 0.7 to 1.5 for the alumina precursor solution.
[0043] In one embodiment, the method for preparing aluminum phosphate sol provided by the present invention includes: dispersing aluminum salt, decationized water, and stabilizer into an alumina precursor solution with a solid content of 5-40% by weight at a temperature of 50℃-95℃ (e.g., 60-80℃) and under stirring conditions, for a stirring time of 10-50 minutes, stopping heating, and then adding phosphate to the above solution at a temperature of 25℃-70℃ (e.g., 35-55℃) and under stirring conditions, reacting for 10-60 minutes until it becomes a transparent colloid.
[0044] The following embodiments will further illustrate the present invention, but are not intended to limit the invention.
[0045] 31 The peak area ratios of P NMR are shown in Table 1. In each embodiment and comparative example, 31 P NMR was performed using a Bruker Avance III 500MHz NMR spectrometer. Peak areas were calculated using an integral method after peak fitting of the resonance spectra. Each chemical shift corresponds to a phosphorus chemical environment, represented by QP. m n Let n represent the number of Al-OP bonds, and n represent the number of POPs, as follows:
[0046] 0±5ppm:QP0 0 Represents one phosphorus-oxygen tetrahedral [PO4] or orthophosphate molecule.
[0047] -7±2ppm:QP0 1 POP represents one molecule of diphosphate.
[0048] -12±2ppm:QP0 2 This represents two diphosphate molecules, signifying POPOP.
[0049] -17±2:QP1 1 This represents one Al-OPOP.
[0050] The particle size was measured using transmission electron microscopy, and the smallest circumscribed circle diameter was defined as the particle size. One hundred particles were randomly selected for measurement, and the average value was taken as the average particle size. The proportion of particles within the 10-30 nanometer range to the total number of particles was defined as the aggregation degree.
[0051] In the various embodiments and comparative examples, the raw materials used to prepare the aluminum phosphate sol are as follows:
[0052] Boehmite: Produced by Shandong Aluminum Plant, Al2O3 content 61% by weight;
[0053] Concentrated phosphoric acid: chemically pure, 85% by weight, produced by Beijing Chemical Plant;
[0054] Deionized water (acidic water): pH 2.8–3.2, sodium oxide content <5 ppm (by mass);
[0055] Kaolin: Catalyst-specific kaolin produced by China Kaolin Corporation, with quartz sand <3.5 wt%, Al2O3 44.0 wt%, Fe2O3 0.56 wt%, Na2O 1.5 wt%, and solid content 80 wt%.
[0056] Anhydrous aluminum sulfate: Sinopharm Group, analytical grade, purity 99%;
[0057] Aluminum nitrate nonahydrate: Sinopharm Group, analytical grade, purity 99%;
[0058] Ammonium dihydrogen phosphate: Sinopharm Group, analytical grade, purity 99%;
[0059] Diamine hydrogen phosphate: Sinopharm Group, analytical grade, purity 99%;
[0060] Oxalic acid: Sinopharm Group, analytical grade, purity 99%;
[0061] Hydrochloric acid: Sinopharm Group, analytical grade, content 36% by mass
[0062] This example demonstrates the preparation of an inorganic binder containing a phosphorus-aluminum compound, as provided in this invention.
[0063] The method for measuring microreactivity is Q / SH 3360 211—2007, and the method for measuring matrix strength is Q / SH 3360208—2006.
[0064] Example 1 of phosphorus aluminum gel
[0065] 0.56 kg of anhydrous aluminum sulfate, 0.25 kg of decationized water, and 0.05 kg of oxalic acid were mixed and stirred, and the mixture was heated to 70°C and stirred for 30 minutes. Then, the temperature was controlled at 45°C, and 0.56 kg of ammonium dihydrogen phosphate was added to the slurry while stirring. The mixture was then stirred at 45°C for 45 minutes to carry out the reaction, thus obtaining aluminum phosphate sol PA-1. The material ratio is shown in Table 1.
[0066] Comparative Example 1 of Phosphate Aluminum Gel
[0067] The adhesive was prepared according to Chinese patent ZL201110180891.X.
[0068] At room temperature (25℃), 0.98 kg of pseudoboehmite (containing 0.6 kg of Al2O3), 0.2 kg of kaolin (0.16 kg on a dry basis), and 0.44 kg of decationized water were mixed and slurried for 30 minutes. While stirring, 2.01 kg of concentrated phosphoric acid (85% by mass) was added to the slurry at a rate of 0.03 kg phosphoric acid / min / kg alumina source. The temperature was raised to 70℃, and the reaction was carried out at this temperature for 45 minutes to obtain the inorganic binder DPA-1 containing phosphorus aluminum compounds. The material ratios are shown in Table 1.
[0069] Comparative Example 2 of Phosphorus Aluminum Gel
[0070] (1) Mix 0.27 kg of boehmite (dry basis) with 0.24 kg of acidic water at 20 °C and stir for 60 min to obtain boehmite slurry;
[0071] (2) 0.40 kg of phosphoric acid was added dropwise to the pseudo-boehmite slurry for the first contact. The temperature after the first contact was 23°C. After adding the phosphoric acid, the mixture was stirred for 30 min. The resulting sample was named DPA-2-1.
[0072] (3) 0.134 kg of phosphoric acid was added dropwise to the mixture (PA-2-1) after the first contact to carry out the second contact, resulting in a mixture at 32°C. The mixture was then stirred and heated to 60°C, and stirred at 60°C for 90 min. The resulting sample was named DPA-2. The material ratio and product properties are shown in Table 1.
[0073] Examples 2-4 of phosphorus aluminum gel
[0074] Examples 2-4 were prepared according to the steps of Example 1. The material proportions are shown in Table 1.
[0075] Comparative Example 3 of Phosphorus Aluminum Gel
[0076] Prepared according to the method of Comparative Example 2 of phosphate aluminum gel, its formulation and product properties are shown in Table 1. Matrix Example 1:
[0077] 55g of the aluminum phosphate gel from Example 1 (on a dry basis) was mixed with 25g of acidified boehmite (on a dry basis, acid-aluminum ratio (hydrochloric acid mass / boehmite dry basis = 0.16), and the solid content of the acidified boehmite slurry was 10% by weight) and 20g of kaolin (on a dry basis). The mixture was stirred for 15 minutes, spray-dried, and calcined at 500°C for 2 hours.
[0078] Matrix Examples 2-4
[0079] Matrix Examples 2-4 were prepared according to the steps of Matrix Example 1.
[0080] Matrix Comparison Examples 1-3
[0081] The matrix comparative examples 1-3 were prepared according to the steps of matrix example 1.
[0082] The properties of the matrices prepared in the matrix examples and comparative examples are shown in Table 1.
[0083] Table 1
[0084]
[0085] As shown in Table 1, the synthesized aluminum phosphate gel of this invention has a QP0 rating. 2 / QP0 0 The higher ratio of dimerized phosphate to free phosphate indicates a higher average particle size, more uniform colloid size, and higher aggregation degree. Compared with Comparative Examples 1 and 2, under the same or higher phosphorus-to-aluminum ratio, the matrix prepared by the phosphorus-aluminum gel synthesized in this invention has higher activity and lower strength, indicating less free phosphate, less impact on the matrix, and better adhesion.
Claims
1. A highly polymerizable aluminum phosphate sol, wherein the aluminum phosphate sol contains 3-15 wt% Al₂O₃, 15-40 wt% P₂O₅, and 0.1-10 wt% stabilizer, with a P / Al weight ratio of 1.6-6, a pH value of 0.5-2.5, and QPO. 2 / QP0 0 =1.5~5; the stabilizer is a weak organic acid, and the aluminum phosphate sol 31 In the p-NMR spectrum, the resonance signal peak area with a chemical shift of 12 ± 2 ppm is QP0. 2 The resonance signal peak area with a chemical shift of 0 ± 2 ppm is QP0. 0 The particle size of the phosphorus aluminum sol is mainly concentrated between 10 and 30 nm.
2. The aluminum phosphate sol according to claim 1, characterized in that, The phosphorus aluminum sol contains 3-12% by weight Al2O3 and 15-32% by weight P2O5.
3. The aluminum phosphate sol according to claim 1, characterized in that, The phosphate aluminum sol contains 0.5-5% by weight of stabilizer.
4. The aluminum phosphate sol according to claim 1, characterized in that, The molar ratio of the organic acid anion to aluminum in the stabilizer is 0.05~0.5:
1.
5. The aluminum phosphate sol according to claim 1 or 4, characterized in that, The stabilizer is selected from at least one of glycolic acid, oxalic acid, acetic acid, malonic acid, malic acid, tartaric acid, succinic acid, adipic acid, maleic acid, itaconic acid, and citric acid.
6. The aluminum phosphate sol according to claim 1, characterized in that, The average particle size of the phosphate aluminum sol is 10~30 nm.
7. A method for preparing the aluminum phosphate sol according to any one of claims 1 to 6, comprising: Under stirring conditions at temperatures of 50℃ to 95℃, aluminum salt source, decationized water, and stabilizer are dispersed into an alumina precursor solution with a solid content of 5 to 40% by weight. Then, under stirring conditions at temperatures of 25℃ to 70℃, phosphate is added to the above solution to initiate the reaction.
8. The method for preparing the aluminum phosphate sol according to claim 7, wherein, The aluminum salt source is one or more of aluminum nitrate, aluminum sulfate, and aluminum chloride, and the pH value of the alumina precursor solution is 0.5~3.
0.
9. The method for preparing the aluminum phosphate sol according to claim 7, wherein, The phosphates mentioned are diamine hydrogen phosphate and / or ammonium dihydrogen phosphate.
10. The method for preparing the aluminum phosphate sol according to claim 7, wherein, The reaction takes 10 to 60 minutes.
11. The application of the aluminum phosphate sol according to claim 1 in the preparation of catalytic cracking catalyst.