Alumina carrier as well as preparation method and application thereof

Abstract

The invention relates to the technical field of alumina forming, and provides an alumina carrier as well as a preparation method and application thereof. The preparation method of the alumina carrier comprises the following steps: roasting a precursor comprising an aluminum-containing component, a peptizing agent, a binder, a morphology control agent and water to prepare the alumina carrier, the aluminum-containing component comprises a first aluminum-containing compound and a second aluminum-containing compound, the particle size of the first aluminum-containing compound is 10-25 [mu] m, and the particle size of the second aluminum-containing compound is 30-60 [mu] m. According to the invention, alumina with two particle sizes is used cooperatively, and a proper morphology control agent is added, so the problem that alumina carriers prepared by forming various alumina are broken when encountering water can be well solved.

Description

Technical Field

[0001] The present invention relates to the technical field of alumina forming, and more specifically, to an alumina carrier and a preparation method and application thereof. Background Art

[0002] Alumina carrier generally refers to formed alumina solid, which is a catalyst carrier widely used in industry. The pore structure, specific surface area, bulk density and other physical and chemical indicators of different alumina carriers are obviously different, which has a significant impact on the performance of the catalyst. Therefore, different chemical reactions often need to be matched with different alumina carriers.

[0003] If only a single alumina raw material is used to prepare an alumina carrier, it is difficult to fully meet the requirements of many chemical reactions. By mixing two or more aluminas in different proportions and in different ways to adjust the physical and chemical indicators of the carrier, it is easier to obtain a catalyst carrier with suitable indicators such as pore size distribution and specific surface area. However, the alumina carrier prepared by mixing multiple aluminas with different physical and chemical properties is prone to uneven stress when exposed to water, resulting in the carrier breaking. This is mainly due to the different cohesiveness and pore size of different aluminas, which cause different adsorption capacities in the liquid and generate different stresses, thus causing the carrier to break.

[0004] The alumina carrier prepared by mixing multiple aluminas is prone to breakage, which has a great impact on the preparation of catalysts and will lead to a significant increase in the cost of catalyst preparation. If the catalyst is used in the production process, it will also increase the resistance of the production system, and even cause shutdown in severe cases. Therefore, it is of great significance to solve the problem of breakage of the alumina carrier prepared by mixing multiple aluminas. Summary of the invention

[0005] The object of the present invention is to provide an alumina carrier and a preparation method thereof, so as to solve the technical problem that the alumina carrier prepared by mixing and forming multiple aluminas in the prior art is prone to breakage.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In a first aspect, the present invention provides a method for preparing an alumina carrier, comprising: subjecting a precursor comprising an aluminum-containing component, a peptizing agent, a binder, a morphology control agent and water to a calcination treatment to obtain the alumina carrier; the aluminum-containing component comprises a first aluminum-containing compound and a second aluminum-containing compound, the first aluminum-containing compound has a particle size of 10 to 25 μm, and the second aluminum-containing compound has a particle size of 30 to 60 μm.

[0008] According to some embodiments of the present invention, the first aluminum-containing compound and the second aluminum-containing compound are the same or different, and are independently selected from any one of pseudo-boehmite, alumina trihydrate, γ-alumina, and θ-alumina.

[0009] According to some embodiments of the present invention, the weight ratio of the aluminum-containing component, the peptizing agent calculated as hydrogen ions, the binder, the morphology control agent and water is (41-65): (0.01-0.1): (1-10): (0.1-5): (5-15), and the weight ratio of the first aluminum-containing compound to the second aluminum-containing compound is (40-55): (1-10).

[0010] According to some embodiments of the present invention, the weight ratio of the aluminum-containing component, the peptizing agent calculated as hydrogen ions, the binder, the morphology control agent and water is (48-58): (0.03-0.08): (3-8): (0.5-2.5): (8-12).

[0011] According to some embodiments of the present invention, the weight ratio of the first aluminum-containing compound to the second aluminum-containing compound is (45-50):(3-8).

[0012] According to some embodiments of the present invention, the morphology control agent is selected from at least one of polyvinyl alcohol, polyethylene glycol, ethyl acetoacetate, and urea, preferably polyvinyl alcohol.

[0013] The present invention can change the surface morphology of the alumina carrier by adding a morphology control agent, avoid the formation of fibrous or flaky crystals, and improve the strength of the alumina pore structure, thereby solving the problem of uneven pore stress after contact with water, easy damage, and further explosion.

[0014] According to some embodiments of the present invention, the peptizing agent is selected from at least one of nitric acid, formic acid, acetic acid and oxalic acid.

[0015] According to some embodiments of the present invention, the binder is selected from at least one of sesbania powder, methyl cellulose, cyclodextrin, and starch.

[0016] According to some embodiments of the present invention, the calcination temperature is 500-600° C. and the calcination time is 4-12 hours.

[0017] According to some embodiments of the present invention, the preparation method further comprises: forming and drying before the calcination process.

[0018] According to some embodiments of the present invention, the preparation method further comprises: performing acid washing and secondary roasting after the roasting treatment.

[0019] In the present invention, the acid in the pickling agent can be selected from various commonly used inorganic acids and organic acids, such as nitric acid, acetic acid, citric acid, etc.

[0020] According to some embodiments of the present invention, the acid used for pickling is H + The ratio of the molar amount of the aluminum element in the alumina carrier is (0.1-2.0):1.

[0021] According to some embodiments of the present invention, the secondary calcination is carried out at a temperature of 600 to 850° C. and for a time of 2 to 24 hours.

[0022] According to some embodiments of the present invention, the drying temperature is 80 to 120° C. and the drying time is 1 to 8 hours.

[0023] According to some embodiments of the present invention, the preparation method comprises the following steps:

[0024] S1. The aluminum-containing component and the binder are mixed to obtain a solid mixture;

[0025] S2. mixing the peptizing agent, the morphology control agent and water to obtain a liquid mixture;

[0026] S3. The solid mixture and the liquid mixture are kneaded, formed, dried, and calcined to obtain a calcined carrier;

[0027] S4. Washing the calcined carrier with acid, and then calcining it for a second time to obtain the alumina carrier.

[0028] In a second aspect, the present invention provides an alumina carrier prepared by the preparation method described in the first aspect.

[0029] According to some embodiments of the present invention, the alumina carrier has only one ammonia adsorption peak below 300° C. This indicates that the alumina carrier provided by the present invention has a certain weak acidity.

[0030] According to some embodiments of the present invention, the strength of the alumina carrier is 75-130 N / 5 mm.

[0031] According to some embodiments of the present invention, the strength of the alumina carrier is 110-130 N / 5 mm.

[0032] It should be noted that if the strength of the alumina carrier exceeds 130N / 5mm, it will be difficult to process in practical applications.

[0033] According to some embodiments of the present invention, the specific surface area of ​​the alumina carrier is 100 to 140 m 2 / g, bulk density is 0.65~1.0g / cm 3 .

[0034] According to some embodiments of the present invention, the specific surface area of ​​the alumina carrier is 110 to 130 m 2 / g, bulk density is 0.9~1.0g / cm 3 .

[0035] In a third aspect, the present invention provides use of the alumina carrier described in the second aspect in a catalyst.

[0036] The beneficial effects of the present invention are at least:

[0037] (1) The present invention uses two types of alumina particle sizes in combination and adds a suitable morphology control agent, which can effectively solve the problem of alumina carriers prepared by forming multiple aluminas breaking when exposed to water.

[0038] (2) The present invention can remove impurities in the carrier skeleton structure, reduce the acidity of the carrier, and inhibit the occurrence of cracking side reactions by adopting the acid washing step. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is the ammonia adsorption diagram of carrier A1 in Example 1.

[0040] Figure 2 This is a scanning electron microscope image of carrier A1 of Example 1.

[0041] Figure 3 This is a scanning electron microscope image of the carrier D3 of comparative example 3. DETAILED DESCRIPTION

[0042] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain this patent in detail and do not limit the scope of protection of the present invention in any way.

[0043] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples, etc., can all be purchased on the market or can be obtained by existing methods; the reagent amounts, unless otherwise specified, are the reagent amounts used in conventional experimental operations; the experimental methods, unless otherwise specified, are all conventional methods.

[0044] In each embodiment and comparative example of the present invention, each performance data is tested according to the following test method:

[0045] (1) Specific surface area: measured using a Micromeritics TriStar 3000 physical adsorption instrument.

[0046] (2) Bulk density: measured in accordance with NB / SH / T 0958-2017, bulk density of molded catalysts and catalyst carriers by mechanical compaction.

[0047] (3) Scanning electron microscope image: Observed using a ZEISS Merlin scanning electron microscope produced by the German ZEISS company.

[0048] (4) Ammonia adsorption experiment: The experiment was conducted on a multi-purpose adsorption system of Pengxiang Company. The ammonia adsorption temperature was 100°C, the carrier gas was He, the flow rate was 30 mL / min, the heating rate was 10°C / min, and a TCD detector was used.

[0049] (5) Water Explosion Test: The prepared alumina carrier was completely immersed in deionized water and taken out after 1 hour. The ratio of the mass of the incomplete particles after sufficient drying to the mass of the initial alumina carrier was the water rupture ratio.

[0050] Example 1

[0051] Weigh 500g of pseudo-boehmite with a D50 of 20μm, 80g of pseudo-boehmite with a D50 of 50μm and 30g of sesbania powder, put them into a kneader and knead them uniformly to obtain a solid mixture; weigh 69.82g of deionized water, 29.08g of nitric acid (65wt%) and 5g of polyvinyl alcohol, mix them uniformly, and then mix them with the solid mixture, and extrude them to obtain a molded precursor; dry the molded precursor at 120°C for 1h, and calcine at 600°C for 4h to obtain a calcined carrier; rinse the calcined carrier with dilute nitric acid with a concentration of 0.8mol / L, and the H + The molar ratio of the aluminum element in the carrier after calcination is 0.1:1; then it is calcined at 850°C for 2h to obtain carrier A1.

[0052] The ammonia adsorption diagram of carrier A1 is shown in Figure 1 As shown, the ammonia adsorption peak is at 218°C.

[0053] The scanning electron microscope image of carrier A1 is as follows Figure 2 As shown, the scanning electron microscope image of carrier D3 is as follows Figure 3 It can be seen that after adding the morphology control agent, the surface uniformity of alumina is improved, the internal stress after contact with water can be reduced, and it is conducive to use as a catalyst carrier.

[0054] Example 2

[0055] Weigh 450g of γ-alumina with a D50 of 10μm, 30g of γ-alumina with a D50 of 60μm and 30g of methyl cellulose, put them into a kneader and knead them evenly to obtain a solid mixture; weigh 80g of deionized water, 13.8g of formic acid and 5g of polyvinyl alcohol, mix them evenly, and then mix them with the solid mixture, and extrude them to obtain a molding precursor; dry the molding precursor at 100°C for 3h, and calcine at 500°C for 10h to obtain a calcined carrier; rinse the calcined carrier with an acetic acid solution with a concentration of 4mol / L, and the molar mass ratio of acetic acid to the calcined carrier is 0.1:1; then calcine at 650°C for 12h to obtain carrier A2.

[0056] Example 3

[0057] Weigh 500g of θ-alumina with a D50 of 10μm, 80g of γ-alumina with a D50 of 60μm and 80g of β-cyclodextrin, put them into a kneader and knead them evenly to obtain a solid mixture; weigh 120g of deionized water, 48g of acetic acid, and 25g of polyvinyl alcohol, mix them evenly, and then mix them with the solid mixture, and extrude them to obtain a molding precursor; dry the molding precursor at 120℃ for 1h, and calcine at 600℃ for 4h to obtain a calcined carrier; rinse the calcined carrier with a citric acid solution with a concentration of 0.1mol / L, and the molar mass ratio of citric acid to the calcined carrier is 2:1; then calcine at 850℃ for 2h to obtain carrier A3.

[0058] Example 4

[0059] The preparation method of the carrier refers to Example 1, except that: the amount of pseudo-boehmite with a D50 of 20 μm is 568 g, and the amount of pseudo-boehmite with a D50 of 50 μm is 12 g.

[0060] The vector A4 was obtained.

[0061] Example 5

[0062] The preparation method of the carrier is similar to that of Example 1, except that: the amount of pseudo-boehmite with a D50 of 20 μm is 470 g, and the amount of pseudo-boehmite with a D50 of 50 μm is 110 g.

[0063] The vector A5 was obtained.

[0064] Example 6

[0065] The preparation method of the carrier is similar to that of Example 1, except that polyvinyl alcohol is replaced by an equal amount of polyethylene glycol.

[0066] The vector A6 was obtained.

[0067] Example 7

[0068] The preparation method of the carrier is similar to that of Example 1, except that polyvinyl alcohol is replaced with an equal mass of ethyl acetoacetate.

[0069] The vector A7 was obtained.

[0070] Example 8

[0071] The preparation method of the carrier is similar to that of Example 1, except that polyvinyl alcohol is replaced with an equal mass of urea.

[0072] The vector A8 was obtained.

[0073] Example 9

[0074] Weigh 500g of pseudo-boehmite with a D50 of 20μm, 80g of pseudo-boehmite with a D50 of 50μm and 30g of sesbania powder, put them into a kneading machine and knead them evenly to obtain a solid mixture; weigh 69.82g of deionized water, 29.08g of nitric acid (65wt%), and 5g of polyvinyl alcohol, mix them evenly, and then mix them with the solid mixture, and extrude them to obtain a molding precursor; dry the molding precursor at 120°C for 1h, and calcine at 600°C for 4h to obtain carrier A9.

[0075] Example 10

[0076] The preparation method of the carrier is similar to that of Example 1, except that: + The molar ratio of the aluminum element in the carrier after calcination is 5:1.

[0077] The vector A10 was obtained.

[0078] Comparative Example 1

[0079] The preparation method of the carrier is the same as that of Example 1, except that the pseudo-boehmite with a D50 of 20 μm is replaced by a pseudo-boehmite with a D50 of 5 μm.

[0080] The vector D1 was obtained.

[0081] Comparative Example 2

[0082] The preparation method of the carrier is the same as that of Example 1, except that the pseudo-boehmite with a D50 of 50 μm is replaced by a pseudo-boehmite with a D50 of 70 μm.

[0083] The vector D2 is obtained.

[0084] Comparative Example 3

[0085] The preparation method of the carrier is similar to that of Example 1, except that no polyvinyl alcohol is added.

[0086] The vector D3 was obtained.

[0087] Carrier performance test results

[0088] The various properties of the carriers prepared in the embodiments and comparative examples were tested, and the results are shown in the following table.

[0089]

[0090]

[0091] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A method for preparing an alumina carrier, characterized in that: The preparation method comprises: subjecting a precursor including an aluminum-containing component, a peptizing agent, a binder, a morphology control agent and water to a calcination treatment to obtain the alumina carrier; the aluminum-containing component comprises a first aluminum-containing compound and a second aluminum-containing compound, the particle size of the first aluminum-containing compound is 10 to 25 μm, and the particle size of the second aluminum-containing compound is 30 to 60 μm.

2. The preparation method according to claim 1, characterized in that: The first aluminum-containing compound and the second aluminum-containing compound are the same or different, and are independently selected from any one of pseudo-boehmite, alumina trihydrate, γ-alumina, and θ-alumina.

3. The preparation method according to claim 1 or 2, characterized in that: The weight ratio of the aluminum-containing component, the peptizing agent calculated as hydrogen ions, the binder, the morphology control agent and water is (41-65): (0.01-0.1): (1-10): (0.1-5): (5-15), and the weight ratio of the first aluminum-containing compound to the second aluminum-containing compound is (40-55): (1-10); Preferably, The weight ratio of the aluminum-containing component, the peptizing agent calculated as hydrogen ions, the binder, the morphology control agent and water is (48-58): (0.03-0.08): (3-8): (0.5-2.5): (8-12); And / or, the weight ratio of the first aluminum-containing compound to the second aluminum-containing compound is (45-50):(3-8).

4. The preparation method according to any one of claims 1 to 3, characterized in that: The morphology control agent is selected from at least one of polyvinyl alcohol, polyethylene glycol, ethyl acetoacetate, and urea, preferably polyvinyl alcohol.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The peptizing agent is selected from at least one of nitric acid, formic acid, acetic acid and oxalic acid; And / or, the binder is selected from at least one of sesbania powder, methyl cellulose, cyclodextrin and starch.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The calcination temperature is 500-600°C and the calcination time is 4-12h; And / or, the preparation method further comprises: forming and drying before the calcination process; And / or, the preparation method further comprises: performing acid washing and secondary roasting after the roasting treatment.

7. The preparation method according to claim 6, characterized in that: The acid used for pickling is H + The ratio of the molar amount of the aluminum element in the alumina carrier is (0.1-2.0):1; And / or, the secondary calcination is carried out at a temperature of 600 to 850° C. and for a time of 2 to 24 hours.

8. An alumina carrier prepared by the preparation method described in any one of claims 1 to 7.

9. The alumina carrier according to claim 8, characterized in that The alumina carrier has only one ammonia adsorption peak below 300°C; and / or, the strength of the alumina carrier is 75 to 130 N / 5 mm; And / or, the specific surface area of ​​the alumina carrier is 100 to 140 m 2 / g, bulk density is 0.65~1.0g / cm 3 .

10. Use of the alumina carrier according to claim 8 or 9 in a catalyst.

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