Alumina particles and preparation method thereof

Abstract

The present invention relates to the field of catalyst carrier preparation and discloses aluminum oxide particles and a method for preparing the same. The method for preparing the aluminum oxide particles of the present invention comprises: 1) mixing a chitosan polymer, an aluminum-containing compound, and water to form slurry A; 2) contacting the slurry A with a modified cellulose colloid to form slurry B; 3) dripping the slurry B into an acidic solution to undergo a cross-linking reaction to obtain solidified particles; and 4) calcining the solidified particles to obtain aluminum oxide particles. The method of the present invention effectively reduces the amount of chitosan polymer used, thereby reducing costs, while ensuring the formation of the aluminum oxide particles. Furthermore, the method has the advantages of simple operation, low energy consumption, low equipment requirements, and a green and clean preparation process.

Description

Technical Field

[0001] The present invention relates to the field of catalyst carrier preparation, and in particular to aluminum oxide particles and a preparation method thereof. Background Art

[0002] Catalyst carriers are important consumables in chemical and industrial catalysis. Alumina is widely used as an industrial catalyst carrier due to its excellent physical and chemical properties and good stability.

[0003] The drop ball method is a common technique for forming alumina particles. Water column forming is a recently proposed drop ball method for forming alumina particles. It utilizes the rapid crosslinking and solidification properties of organic polymers and reaction solutions. Alumina particles are prepared by mixing organic polymers with aluminum compounds and dropping them into a water column. This forming method has the advantages of fast forming speed, high efficiency, and a pollution-free preparation process. However, this method still has the potential to further reduce costs. In order to reduce the preparation cost of alumina carriers, there have been many studies on improving this method. For example, CN102718241A discloses a method for preparing spherical alumina particles by sodium alginate-assisted forming. Sodium alginate and pseudo-boehmite are mixed into a suspension and dropped into an aqueous solution of metal ions to form a gel composite sphere. The spherical alumina particles are then washed, dried, and calcined. This method uses cheap sodium alginate as a crosslinking agent to reduce the synthesis cost. However, because sodium alginate cannot react completely, this method leaves varying degrees of sodium residue on the surface of the alumina after calcination. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and to provide an alumina particle. The method is a method for preparing alumina particles by improving low-concentration polymer-assisted molding by modified cellulose. On the basis of ensuring that the alumina particle carrier is well molded, the shaping effect of cheap modified cellulose is utilized to reduce the amount of chitosan polymer in the slurry, thereby reducing the preparation cost of the alumina carrier. In addition, the method has the advantages of simple operation and low equipment requirements.

[0005] In order to achieve the above object, the present invention provides a method for preparing aluminum oxide particles in a first aspect, wherein the method comprises the following steps:

[0006] 1) Mixing chitosan polymer, aluminum-containing compound and water to form slurry A;

[0007] 2) contacting the slurry A with a modified cellulose colloid to prepare slurry B;

[0008] 3) dropping the slurry B into an acidic solution to undergo a cross-linking reaction to obtain solidified particles;

[0009] 4) calcining the solidified particles to obtain alumina particles.

[0010] Preferably, the weight ratio of the chitosan polymer to the aluminum-containing compound is 1:1-50, preferably 1:5-30, and more preferably 1:10-20.

[0011] Preferably, the weight ratio of the total weight of the chitosan polymer and the aluminum-containing compound to water is 1:1.5-5, preferably 1:2-2.5.

[0012] Preferably, the chitosan polymer is one or more of chitosan, carboxymethyl chitosan, hydroxyethyl chitosan, hydroxypropyl chitosan and carboxymethylated hydroxypropyl chitosan.

[0013] Preferably, the aluminum-containing compound is one or more of pseudo-boehmite, alumina, aluminum hydroxide and aluminum sulfate.

[0014] Preferably, the modified cellulose colloid is obtained by mixing modified cellulose with a solvent.

[0015] Preferably, the modified cellulose is one or more of hydroxypropyl methylcellulose, hydroxyethyl cellulose and phenylpropyl methylcellulose.

[0016] Preferably, the content of modified cellulose in the modified cellulose colloid is 5% by weight or more, preferably 5-20% by weight, more preferably 5-10% by weight, and further preferably 6-8% by weight.

[0017] Preferably, the solvent is water.

[0018] Preferably, in step 2), the weight ratio of the slurry A calculated based on the weight of the aluminum-containing compound to the modified cellulose colloid calculated based on the weight of the modified cellulose is 1:0.01-0.05, preferably 1:0.02-0.04, more preferably 1:0.02-0.03.

[0019] Preferably, the acidic solution is one or more of a sulfuric acid aqueous solution, a nitric acid aqueous solution, a hydrochloric acid aqueous solution, an acetic acid aqueous solution, an oxalic acid aqueous solution and a citric acid aqueous solution.

[0020] Preferably, the molar concentration of the acidic solution is above 0.1 mol / L, preferably 0.2-0.5 mol / L.

[0021] Preferably, the cross-linking reaction conditions include: temperature of 5-45° C. and time of 0.5-5 hours.

[0022] Preferably, the calcination conditions include: a temperature of 500-1200° C. and a time of 1-10 hours.

[0023] Preferably, the calcination conditions include: a temperature of 600-800° C. and a time of 1-4 hours.

[0024] According to a second aspect of the present invention, provided are aluminum oxide particles prepared by the method for preparing aluminum oxide particles of the present invention.

[0025] Through the above technical solution, this method effectively reduces the amount of chitosan polymer used, thereby reducing costs, while ensuring the formation of alumina particles. It also has the advantages of simple operation, low energy consumption, low equipment requirements, and a green and clean preparation process. Furthermore, the prepared alumina particles have high strength and specific surface area. DETAILED DESCRIPTION

[0026] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0027] According to a first aspect of the present invention, a method for preparing aluminum oxide particles is provided, wherein the method comprises the following steps:

[0028] 1) Mixing chitosan polymer, aluminum-containing compound and water to form slurry A;

[0029] 2) contacting the slurry A with a modified cellulose colloid to prepare slurry B;

[0030] 3) dropping the slurry B into an acidic solution to undergo a cross-linking reaction to obtain solidified particles;

[0031] 4) calcining the solidified particles to obtain alumina particles.

[0032] According to the present invention, in step 1), the amount of the chitosan polymer can be selected according to the amount of the aluminum-containing compound. Preferably, the weight ratio of the chitosan polymer to the aluminum-containing compound is 1:1-50; more preferably, the weight ratio of the chitosan polymer to the aluminum-containing compound is 1:5-30; further preferably, the weight ratio of the chitosan polymer to the aluminum-containing compound is 1:10-20.

[0033] According to the present invention, in step 1), the amount of water can be selected according to the amount of the chitosan polymer and the aluminum-containing compound. Preferably, the weight ratio of the total weight of the chitosan polymer and the aluminum-containing compound to water is 1:1.5-5. More preferably, the weight ratio of the total weight of the chitosan polymer and the aluminum-containing compound to water is 1:2-2.5.

[0034] According to the present invention, preferably, the chitosan polymer is one or more of chitosan, carboxymethyl chitosan, hydroxyethyl chitosan, hydroxypropyl chitosan and carboxymethylated hydroxypropyl chitosan; more preferably, the chitosan polymer is one or more of chitosan, carboxymethyl chitosan, hydroxyethyl chitosan and hydroxypropyl chitosan; further preferably, the chitosan polymer is carboxymethyl chitosan.

[0035] According to the present invention, preferably, the aluminum-containing compound is one or more of pseudo-boehmite, aluminum oxide, aluminum hydroxide and aluminum sulfate; more preferably, the aluminum-containing compound is pseudo-boehmite.

[0036] According to the present invention, in step 1), the mixing temperature is not particularly limited, for example, it can be carried out at room temperature (5-45° C.), and the mixing time is not particularly limited, as long as a uniformly mixed slurry A can be obtained.

[0037] According to the present invention, in step 2), the modified cellulose colloid is preferably obtained by mixing modified cellulose with a solvent.

[0038] Preferably, the solvent is one or more of water and a solvent in which the modified cellulose can be dissolved; more preferably, the solvent is water.

[0039] The mixing temperature is not particularly limited as long as a colloid can be obtained. For example, the mixing can be performed at 5-90°C.

[0040] In a preferred embodiment of the present invention, the modified cellulose colloid is mixed with hot water (eg, 60-80° C.) to obtain the modified cellulose colloid.

[0041] According to the present invention, preferably, the content of modified cellulose in the modified cellulose colloid is 5% by weight or more; more preferably, the content of modified cellulose in the modified cellulose colloid is 5-20% by weight; further preferably, the content of modified cellulose in the modified cellulose colloid is 5-10% by weight; further preferably, the content of modified cellulose in the modified cellulose colloid is 6-8% by weight.

[0042] According to the present invention, preferably, the modified cellulose is one or more of hydroxypropyl methylcellulose, hydroxyethyl cellulose and phenylpropyl methylcellulose; more preferably, the modified cellulose is phenylpropyl methylcellulose.

[0043] According to the present invention, the amount of the modified cellulose colloid can be selected according to the amount of the aluminum-containing compound. Preferably, in step 2), the weight ratio of the slurry A calculated by weight of the aluminum-containing compound to the modified cellulose colloid calculated by weight of the modified cellulose is 1:0.01-0.05; more preferably, in step 2), the weight ratio of the slurry A calculated by weight of the aluminum-containing compound to the modified cellulose colloid calculated by weight of the modified cellulose is 1:0.02-0.04; further preferably, in step 2), the weight ratio of the slurry A calculated by weight of the aluminum-containing compound to the modified cellulose colloid calculated by weight of the modified cellulose is 1:0.02-0.03.

[0044] According to the present invention, in step 2), the contact temperature is not particularly limited, for example, it can be carried out at room temperature (5-45°C), and the contact time is not particularly limited, as long as a uniformly mixed slurry B can be obtained.

[0045] According to the present invention, preferably, in step 3), the acidic solution is one or more of aqueous sulfuric acid solution, aqueous nitric acid solution, aqueous hydrochloric acid solution, aqueous acetic acid solution, aqueous oxalic acid solution and aqueous citric acid solution; more preferably, the acidic solution is aqueous acetic acid solution.

[0046] According to the present invention, preferably, the molar concentration of the acidic solution is above 0.1 mol / L; more preferably, the molar concentration of the acidic solution is 0.2-10 mol / L, preferably 0.2-5 mol / L, more preferably 0.2-1 mol / L, further preferably 0.2-0.5 mol / L.

[0047] In a preferred embodiment of the present invention, the acidic solution is an aqueous solution of acetic acid with a concentration of 20-25% by weight.

[0048] According to the present invention, the amount of the acidic solution used is sufficient as long as it can ensure that the slurry B dripped therein can undergo a cross-linking reaction to obtain solidified particles. The amount used can be the conventional amount used in the art. For example, relative to 1 part by weight of the slurry B, the amount of the acidic solution used is 0.1 parts by weight or more, preferably 1 part by weight or more, more preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and preferably 100 parts by weight or less, more preferably 50 parts by weight or less, and further preferably 20 parts by weight or less.

[0049] According to the present invention, preferably, the conditions for the cross-linking reaction include: temperature of 5-45° C., and time of 0.5-5 hours; more preferably, the conditions for the cross-linking reaction include: temperature of 15-30° C., and time of 1-2 hours.

[0050] According to the present invention, after the cross-linking reaction is completed, the solidified particles can be separated from the reaction solvent. Preferably, the solidified particles are dried.

[0051] The separation can be carried out by a solid-liquid separation method commonly used in the art, for example, the solidified particles can be directly removed from the reaction solution or filtered to obtain solidified particles. In addition, the drying can be air-dried or oven-dried.

[0052] According to the present invention, preferably, in step 4), the calcination conditions include: temperature of 500-1200° C., time of 1-10 hours; more preferably, the calcination conditions include: temperature of 600-800° C., time of 1-4 hours.

[0053] According to a second aspect of the present invention, provided are aluminum oxide particles prepared by the method for preparing aluminum oxide particles of the present invention.

[0054] The method of the present invention effectively reduces the amount of chitosan polymer used, thereby lowering costs, while ensuring the formation of alumina particles. It also offers advantages such as simple operation, low energy consumption, minimal equipment requirements, and a green and clean preparation process. Furthermore, the resulting alumina particles exhibit high strength and specific surface area.

[0055] The present invention will be described in detail below through examples, but the present invention is not limited to the following examples.

[0056] In the following examples, the average strength was measured using the Standard Test Method for Single Particle Crush Strength of Molded Catalysts and Catalyst Carriers (ASTM D4179-11(2017)), and the specific surface area and pore volume were measured using the gas adsorption BET method (GB / T 19587-2017).

[0057] Example 1

[0058] 1) Dissolve 7.5 g of modified cellulose (specifically phenylpropyl methylcellulose, purchased from Taian Ruitai New Materials Co., Ltd.) in 100 ml of hot water to prepare a homogeneous colloid.

[0059] 2) 8 g of pseudo-boehmite was mixed with 20 ml of water, and 0.4 g of carboxymethyl chitosan (purchased from Aladdin Reagent Co., Ltd., the same below) was added to form slurry A.

[0060] 3) Add 3.1 g of modified cellulose homogeneous colloid to the slurry A, stir and mix uniformly to obtain slurry B.

[0061] 4) Slurry B was dripped into acetic acid solution with a concentration of 25 wt% to form solidified particles. After reacting for 1 hour, the particles were removed and dried naturally. The dried particles were placed in a muffle furnace, heated to 650°C in 0.5 hours and maintained for 1.5 hours. Analysis of the product showed that it was well-formed, with a particle size of 1.8±0.1 mm, an average strength of 48 N / particle, and a specific surface area of ​​230.9 m 2 / g, pore volume 0.32cm 3 / g.

[0062] Example 2

[0063] 1) Dissolve 7.5 g of modified cellulose (specifically phenylpropyl methylcellulose, purchased from Taian Ruitai New Materials Co., Ltd.) in 100 ml of hot water to prepare a homogeneous colloid.

[0064] 2) 8 g of pseudo-boehmite was mixed with 20 ml of water, and 0.6 g of carboxymethyl chitosan was added to form slurry A.

[0065] 3) Add 3.1 g of modified cellulose homogeneous colloid to the slurry A, stir and mix uniformly to obtain slurry B.

[0066] 4) Slurry B was dripped into 25 wt% acetic acid solution to form solidified particles. After 1 hour of reaction, the particles were removed and dried naturally. The dried particles were placed in a muffle furnace, heated to 650°C in 0.5 hours and maintained for 1.5 hours. Analysis of the product showed that the particles were well formed, with a particle size of 1.8±0.1 mm, an average strength of 32 N / particle, and a specific surface area of ​​219.8 m 2 / g, pore volume 0.32cm 3 / g.

[0067] Example 3

[0068] 1) Dissolve 7.5 g of modified cellulose (specifically phenylpropyl methylcellulose, purchased from Taian Ruitai New Materials Co., Ltd.) in 100 ml of hot water to prepare a homogeneous colloid.

[0069] 2) 8 g of pseudo-boehmite was mixed with 20 ml of water, and 0.8 g of carboxymethyl chitosan was added to form slurry A.

[0070] 3) Add 3.1 g of modified cellulose homogeneous colloid to the slurry A, stir and mix uniformly to obtain slurry B.

[0071] 4) Slurry B was dripped into 25 wt% acetic acid solution to form solidified particles. After 1 hour of reaction, the particles were removed and dried naturally. The dried particles were placed in a muffle furnace, heated to 650°C in 0.5 hours and maintained for 1.5 hours. Analysis of the product showed that the particles were well formed, with a particle size of 1.8±0.1 mm, an average strength of 22 N / particle, and a specific surface area of ​​213.2 m 2 / g, pore volume 0.31cm 3 / g.

[0072] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing aluminum oxide particles, characterized in that: The method comprises the following steps, 1) Mixing chitosan polymer, aluminum-containing compound and water to form slurry A; 2) contacting the slurry A with a modified cellulose colloid to prepare slurry B; 3) dropping the slurry B into an acidic solution to undergo a cross-linking reaction to obtain solidified particles; 4) calcining the solidified particles to obtain alumina particles, The modified cellulose is one or more of hydroxypropyl methylcellulose, hydroxyethyl cellulose and phenylpropyl methylcellulose. In step 2), the weight ratio of the slurry A based on the weight of the aluminum-containing compound to the modified cellulose colloid based on the weight of the modified cellulose is 1:0.01-0.05, The chitosan polymer is carboxymethyl chitosan, The weight ratio of the chitosan polymer to the aluminum-containing compound is 1:5-30. The weight ratio of the total weight of the chitosan polymer and the aluminum-containing compound to water is 1:1.5-5.

2. The method according to claim 1, wherein The weight ratio of the chitosan polymer to the aluminum-containing compound is 1:10-20.

3. The method according to claim 1, wherein The weight ratio of the total weight of the chitosan polymer and the aluminum-containing compound to water is 1:2-2.

5.

4. The method according to any one of claims 1 to 3, wherein: The aluminum-containing compound is one or more of pseudo-boehmite, aluminum hydroxide and aluminum sulfate.

5. The method according to any one of claims 1 to 3, wherein: The modified cellulose colloid is obtained by mixing modified cellulose with a solvent.

6. The method according to claim 5, wherein: The content of modified cellulose in the modified cellulose colloid is 5% by weight or more.

7. The method according to claim 6, wherein: The content of modified cellulose in the modified cellulose colloid is 5-20% by weight.

8. The method according to claim 7, wherein: The content of modified cellulose in the modified cellulose colloid is 5-10% by weight.

9. The method according to claim 7, wherein: The content of modified cellulose in the modified cellulose colloid is 6-8% by weight.

10. The method according to claim 5, wherein The solvent is water.

11. The method according to any one of claims 1 to 3, wherein: In step 2), the weight ratio of the slurry A calculated based on the weight of the aluminum-containing compound to the modified cellulose colloid calculated based on the weight of the modified cellulose is 1:0.02-0.

04.

12. The method according to claim 11, wherein In step 2), the weight ratio of the slurry A calculated based on the weight of the aluminum-containing compound to the modified cellulose colloid calculated based on the weight of the modified cellulose is 1:0.02-0.

03.

13. The method according to any one of claims 1 to 3, wherein: The acidic solution is one or more of a sulfuric acid aqueous solution, a nitric acid aqueous solution, a hydrochloric acid aqueous solution, an acetic acid aqueous solution, an oxalic acid aqueous solution and a citric acid aqueous solution.

14. The method according to claim 13, wherein The molar concentration of the acidic solution is greater than 0.1 mol / L.

15. The method according to claim 14, wherein The molar concentration of the acidic solution is 0.2-0.5 mol / L.

16. The method according to any one of claims 1 to 3, wherein: The cross-linking reaction conditions include: temperature of 5-45° C. and time of 0.5-5 hours.

17. The method according to any one of claims 1 to 3, wherein: The calcination conditions include: a temperature of 500-1200° C. and a time of 1-10 hours.

18. The method according to claim 17, wherein The calcination conditions include: a temperature of 600-800° C. and a time of 1-4 hours.

19. Alumina particles prepared by the method for preparing alumina particles according to any one of claims 1 to 18.