Alumina carrier and its preparation method and application

Abstract

The present invention provides an alumina carrier and a preparation method thereof. The alumina carrier provided by the present invention is mainly obtained by improving the alumina carrier preparation method. During the preparation process of the alumina carrier, a certain amount of α-Al2O3 powder is added. The particle size, impurity content, etc. of the α-Al2O3 powder used must meet certain conditions. The prepared alumina carrier has the advantages of low bulk density, large water absorption, large pore volume and large average pore size. Due to the increase in pore volume and water absorption of the alumina carrier, the active metal can be more evenly distributed on the surface of the alumina carrier. At the same time, due to the increase in average pore size, it is conducive to the diffusion of reactants and products, thereby improving reaction activity and selectivity.

Description

Technical Field

[0001] The present invention belongs to the field of catalysts, and in particular relates to an alumina carrier and a preparation method and application thereof. Background Art

[0002] Alumina supports are widely used in the petrochemical industry, such as as catalyst supports for the selective hydrogenation of alkynes, pyrolysis gasoline hydrogenation, and ethylene oxide oxidation. Different applications require different alumina supports, with some requiring larger pore sizes and stronger acidity, while others require better thermal stability and a gradient acidity distribution. Alumina supports generally possess advantages such as large surface area, a rich pore structure, and good thermal stability. Their microporous structure, in particular, possesses properties required for many catalytic reactions, such as diffusion properties and surface acidity. Eight different crystalline forms of alumina (γ-, χ-, κ-, δ-, η-, θ-, α-, and β-) can be obtained through different preparation methods and calcination temperatures. Properties vary between each crystalline form, and even within the same crystalline form, macro- and microstructural properties (such as density, pore volume, and pore size distribution) can vary significantly.

[0003] Industrial alumina supports are typically made from pseudo-boehmite powder and fast-release alumina powder. Using compression molding, extrusion molding, and rotational molding, alumina can be formed into shapes such as spheres, toothed spheres, and bars, and to specific sizes, depending on the intended use. The physical properties of the pseudo-boehmite powder, the molding parameters, and the choice of molding additives all influence the physical properties of the final alumina support, and thus the performance of the resulting catalyst. By optimizing the alumina powder refining process and molding methods, the physical properties of the alumina support can be adjusted, and extensive research has been conducted in this area.

[0004] Chinese patent CN103816940A discloses a method for preparing an alumina carrier, which uses alumina trihydrate or diaspore, which are widely available and inexpensive, as the main raw materials, aluminum sol as a binder, and adds fluoride, alkaline earth metal compounds and silicides. Through kneading-extrusion-molding, and controlling the roasting temperature and heating rate, a catalyst carrier with high strength and large specific surface area is obtained.

[0005] Chinese patent CN106669850A discloses a method for preparing an alumina support. This method uses chloroaluminate-modified pseudo-boehmite as a raw material, along with boric acid or phosphoric acid compounds, alkyl chlorides, and a binder. After uniform mixing, the mixture is extruded, shaped, dried, and calcined to produce a macroporous alumina support. This method produces a support with large pore sizes and volumes, exhibiting a dual pore distribution.

[0006] Chinese patent CN106669850A discloses a method for preparing an alumina carrier. Using alumina powder and glass microspheres as raw materials, kaolin as a binder, and resin as a pore-forming agent, the process involves vacuum kneading, isostatic pressing, and calcining the resulting spherical body. The resulting carrier exhibits high strength, high water absorption, and high thermal conductivity.

[0007] Existing technology solutions have long and complex preparation processes, require the addition of numerous additives, and result in high production costs. Furthermore, the physical properties of the alumina supports produced are not stable across batches. There is a need to develop alumina supports with simple preparation methods, stable support properties, and the ability to be used in the preparation of a variety of catalysts. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention provides an alumina carrier and a method for preparing the same. During the preparation of the alumina carrier, a certain amount of α-Al2O3 powder is added. The particle size and impurity content of the α-Al2O3 powder must meet certain conditions, resulting in a reduced bulk density, significantly increased water absorption, increased pore volume, and an increased average pore size, resulting in better overall performance. The alumina carrier is used in catalyst preparation, facilitating the uniform distribution of metal active components and the diffusion of reactants and products. In particular, it is used in the preparation of selective hydrogenation catalysts. Due to the increased average pore size, the generated products can diffuse more quickly, avoiding over-hydrogenation.

[0009] One of the objects of the present invention is to provide an alumina carrier, wherein the water absorption rate of the alumina carrier is 40-70%, the pore volume is 0.6-0.9 ml / g, and the most probable pore diameter is 0.100-0.300 μm; preferably, the water absorption rate of the alumina carrier is 50-65%, the pore volume is 0.63-0.8 ml / g, and the most probable pore diameter is 0.120-0.250 μm.

[0010] Preferably, the specific surface area of the alumina carrier is 5 to 120 m 2 / g, bulk density of 0.3-0.9g / ml, strength of 20-200Nm; preferably, the specific surface area of the alumina carrier is 20-100m 2 / g, bulk density is 0.5-0.8g / ml, and strength is 30-100Nm.

[0011] The shape of the alumina carrier includes but is not limited to powder, granular, spherical, flake, toothed ball, strip or clover-shaped strip.

[0012] The alumina support further contains 0.01 to 1 wt% of alkali metals, alkaline earth metals, and / or rare earth metals. The alkali metals are selected from at least one of Na, K, and Li; the alkaline earth metals are selected from at least one of Mg and Ca; and the rare earth metals are selected from at least one of La, Ce, Pr, and Y, preferably at least one of La and Ce. These metal elements can further enhance the strength, specific surface area, pore volume, and other properties of the alumina support.

[0013] A second object of the present invention is to provide a method for preparing the above-mentioned alumina carrier, comprising the steps of powder mixing, kneading and forming, and drying and calcining. Preferably, the method specifically comprises the following steps:

[0014] Step 1: uniformly mix the components including alumina powder and additives to obtain a powder to be kneaded;

[0015] Step 2: adding the acidic aqueous solution to the powder to be kneaded and kneading into a shape;

[0016] Step 3: Dry and calcine the kneaded product to obtain the alumina support.

[0017] Specifically,

[0018] In step 1, the alumina powder includes pseudo-boehmite powder, α-Al2O3 powder, and optionally alumina trihydrate powder and / or fast-deoxidizing alumina powder;

[0019] The pseudo-boehmite powder can be commonly used pseudo-boehmite. Preferably, the specific surface area of the pseudo-boehmite powder is 200 to 300 m 2 / g, pore volume 0.5~1.2ml / g, bulk density 0.2~0.4g / ml;

[0020] The α-Al2O3 powder can be obtained by calcining high-purity aluminum hydroxide, and the calcination temperature should be greater than 1300°C. Fluorine-containing compounds can be added during the calcination process to form flaky aluminum oxide particles. At this time, the F content in the α-Al2O3 powder is not greater than 0.1%; the α-Al2O3 powder can also be obtained by calcining the pseudo-boehmite powder used for molding, and the calcination temperature should be greater than 1300°C. Preferably, the α-Al2O3 powder is obtained by calcining pseudo-boehmite powder. In the α-Al2O3 powder, the α-Al2O3 content is greater than 95%, the particle size of the powder is 2 to 100 μm, and the mass content of Na, Fe, and Si is less than 0.1%;

[0021] In step 1, the α-Al2O3 powder is 5 to 30 wt% of the total weight of the alumina powder, preferably 5 to 20 wt%;

[0022] The alumina trihydrate and the fast-dehydrating alumina can both be selected from commonly used components. For example, the alumina trihydrate powder can be selected from at least one of gibbsite, bayerite, and norhydrite. The fast-dehydrating alumina powder is obtained by rapid dehydration of aluminum hydroxide, wherein the mass content of Na and Fe is less than 0.1%; the mass of the alumina trihydrate powder accounts for 0 to 10% of the total mass of the alumina powder; the mass of the fast-dehydrating alumina powder accounts for 0 to 10% of the total mass of the alumina powder.

[0023] In step 1, the auxiliary agent is selected from at least one of a silicon-containing compound and a forming pore-forming auxiliary agent;

[0024] Wherein, the silicon-containing compound is selected from water-insoluble silicon-containing compounds, preferably selected from at least one of dry silica gel, nano silicon oxide, and silicon carbide; wherein the nano silicon oxide and dry silica gel preferably have an average particle size of less than 120 nm;

[0025] Calculated by the mass percentage of Si element, the Si element in the silicon-containing compound is 0 to 1.35% of the total weight of the alumina powder, preferably 0 to 0.9%;

[0026] The forming pore-forming aid is selected from at least one of natural organic matter, high molecular polymer, and decomposable alkaline compound, preferably selected from at least one of sesbania powder, starch, methyl cellulose, hydroxypropyl methyl cellulose, sodium hydroxymethyl cellulose, polyethylene microspheres, polystyrene, polyethylene oxide, polyethylene glycol, polyvinyl alcohol, sodium polyacrylate, polyethylene glycol, polyacrylate acrylic acid, urea, methylamine, ethylenediamine, ammonium carbonate, and ammonium bicarbonate; those skilled in the art can select one or more forming pore-forming aids based on experience, and the amount of the forming pore-forming aid is 0 to 20% of the total mass of the alumina carrier, preferably 0 to 10%.

[0027] The powder mixing in step 1 can be carried out in a dedicated mixer, or the powder can be added to a kneader and dry-mixed for a certain period of time without adding a solution. Those skilled in the art can determine the required mixing time based on experience. Powder mixing is an important step in carrier preparation, and can be ensured to be uniformly mixed by optimizing the mixer structure, extending the mixing time, and other methods.

[0028] In step 2:

[0029] The acid in the acidic aqueous solution is selected from at least one of an organic acid, an inorganic acid, and an acidic salt compound, preferably selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, oxalic acid, citric acid, and ammonium dihydrogen phosphate, more preferably selected from at least one of nitric acid, acetic acid, oxalic acid, and citric acid;

[0030] The mass percentage concentration of the acid in the acidic aqueous solution is 0.1 to 10%, preferably 0.1 to 5%;

[0031] The weight ratio of the acidic aqueous solution to the powder to be kneaded is 0.5 to 5:1, preferably 0.6 to 2:1; those skilled in the art can adjust the amount of acid in the acidic aqueous solution according to the plasticity of the billet after kneading and the specific surface area, strength, bulk density and other data of the carrier after high-temperature roasting.

[0032] A soluble auxiliary agent is further added to the acidic aqueous solution in step 2. Preferably, the soluble auxiliary agent is selected from at least one of an alkali metal compound, an alkaline earth metal compound, and a rare earth metal compound; wherein the alkali metal compound is selected from inorganic salt compounds of metals Na, K, and Li, and is preferably selected from at least one of nitrates and chlorides of metals Na, K, and Li; the alkaline earth metal compound is selected from inorganic salt compounds of metals Mg and Ca, and is preferably selected from at least one of nitrates and chlorides of metals Mg and Ca; the rare earth metal compound is selected from soluble rare earth metal salt compounds, and is preferably selected from at least one of nitrates and chlorides of La, Ce, Pr, and Y, and is more preferably selected from at least one of nitrates and chlorides of La and Ce; and the metal in the soluble auxiliary agent accounts for 0 to 1.35% of the total amount of the alumina powder, preferably 0 to 0.9%, based on the mass percentage of the metal element.

[0033] In step 2, the kneading and molding step involves adding an acidic aqueous solution containing a soluble additive to the uniformly mixed powder. Through continuous mixing and kneading, a portion of the alumina powder reacts with the acid to form a plastic billet, which is then extruded into the desired shape and size. The kneading time and extrusion pressure are related to factors such as the equipment size, the composition of the alumina powder, and the composition of the acid solution, and can be determined by those skilled in the art based on experience.

[0034] The drying and calcining step in step 3 is to dry out the moisture in the green embryo after kneading and forming. During the high-temperature calcination process, a solid phase reaction occurs, and the alumina grains adhere together to form an alumina carrier with a certain strength.

[0035] Preferably, the drying temperature is 60-150°C, and the drying time is 3-48 hours; the roasting temperature is 800-1200°C, and the roasting time is 3-48 hours;

[0036] During the calcination process, different heating rates are selected according to different powder raw materials and molding additives. Preferably, when the temperature is below 500°C, the heating rate is 30-150°C / h, and when the temperature is above 500°C, the heating rate is 100-280°C / h.

[0037] A third object of the present invention is to provide the above-mentioned alumina carrier or the alumina carrier prepared by the above-mentioned preparation method, which is used for the preparation of catalysts in the petrochemical field.

[0038] The α-Al2O3 powder added in the present invention is Al2O3 powder that has been subjected to high-temperature calcination treatment, and its particle size and volume will not shrink during the subsequent calcination process; while the pseudo-boehmite powder grains used for molding will gradually dehydrate during the high-temperature calcination process to form grains with a higher degree of crystallization, and adhesion will occur between the grains; during the high-temperature calcination process, the two types of crystal particles do not undergo synchronous changes in particle size and volume, and the grains of the α-Al2O3 powder play a supporting and dispersing role on the pseudo-boehmite grains, thereby increasing the pore size and pore volume of the obtained alumina carrier, and subsequently increasing the water absorption rate.

[0039] The present invention adds α-Al2O3 powder during the preparation process, selects alumina powder of a certain composition, uses molding additives such as sesbania powder, starch, and cellulose, uses additives such as La, Ce, and Mg, limits the type and amount of the acid solution used, and controls the drying and high-temperature calcination conditions. This allows the preparation of an alumina support with a larger pore volume, pore diameter, and water absorption rate, a smaller bulk density, and better overall performance. The alumina support preparation method provided by the present invention is simple. DETAILED DESCRIPTION

[0040] The present invention will be described in detail below with reference to specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art to the present invention based on the contents of the present invention still fall within the scope of protection of the present invention.

[0041] The test instruments and test conditions used in the examples are as follows:

[0042] The specific surface area was measured using the nitrogen physical adsorption BET method;

[0043] The bulk density was calculated by measuring the mass of 100 mL of alumina support, and the average value was obtained after three measurements for each sample;

[0044] The pore volume and the most probable pore diameter were measured by mercury intrusion method, which was carried out according to the general pore volume measurement method of alumina support.

[0045] The strength was measured using a universal particle strength measuring instrument, and the average value of the measurement results of 20 carrier particles was taken;

[0046] The water absorption rate is obtained by taking 20 g of the alumina carrier, soaking it in water for 10 minutes, taking it out and draining the surface water, and measuring the weight increase.

[0047] Example 1

[0048] Weigh 180g pseudo-boehmite powder, 20g α-Al2O3 powder, 8g sesbania powder, and 10g starch, mix them evenly in a mixer, and transfer them to a kneader. The pseudo-boehmite powder has a specific surface area of 252.4m 2 / g, pore volume 0.944ml / g, and bulk density 0.33g / ml; α-Al2O3 powder obtained from this pseudo-boehmite is calcined at 1400°C. It has an α-Al2O3 content of 98.0%, an average particle size of 5μm, and Na, Fe, and Si mass contents of less than 0.01%. 2.00g concentrated nitric acid, 2.00g acetic acid, and 1.517g lanthanum nitrate are weighed and added to 200g deionized water to prepare a mixed solution. This mixed solution is added to the uniformly mixed powder, thoroughly kneaded, and then extruded and pelletized to produce spherical particles with a particle size of 4-6mm. After drying at 120°C for 12 hours, the mixture is calcined at 1175°C for 6 hours, with a heating rate of 100°C / hr below 500°C and 200°C / hr above 500°C. This yields alumina support S1 with a La loading of 0.35%.

[0049] Example 2

[0050] Weigh 150g of pseudo-boehmite powder, 50g of α-Al2O3 powder, 6g of sesbania powder, 5g of starch, and 3g of cross-linked polyethylene microspheres with a particle size of about 40 microns, mix them evenly in a mixer, and transfer them to a kneader. The pseudo-boehmite powder has a specific surface area of 252.4m 2 / g, pore volume 0.944ml / g, and bulk density 0.33g / ml; α-Al2O3 powder obtained from this pseudo-boehmite is calcined at 1500°C, with an α-Al2O3 content of 99.5%, an average particle size of 12μm, and Na, Fe, and Si mass contents less than 0.01%. 3.00g of concentrated nitric acid and 1.745g of cerium nitrate are weighed and added to 200g of deionized water to prepare a mixed solution. The mixed solution is added to the uniformly mixed powder, thoroughly kneaded, and then extruded and pelletized to obtain spherical particles with a particle size of 4-6mm. The drying conditions are the same as in Example 1, and the calcination temperature is the same as in Example 1, at 1165°C, to obtain an alumina carrier S2 with a Ce loading of 0.40%.

[0051] Example 3

[0052] Weigh 188g of pseudo-boehmite powder, 12g of α-Al2O3 powder, 8g of sesbania powder, 2g of cellulose, and 3g of ammonium carbonate, mix them evenly in a mixer, and transfer them to a kneader. The specific surface area of the pseudo-boehmite powder is 245.7m 2 / g, pore volume 0.869ml / g, bulk density 0.22g / ml; α-Al2O3 powder was the same as in Example 1. 1.00g concentrated nitric acid, 3g acetic acid, and 0.365g potassium nitrate were weighed and added to 200g deionized water to prepare a mixed solution. This mixed solution was added to the uniformly mixed powders, thoroughly kneaded, and then extruded and pelletized to obtain spherical particles with a particle size of 4-6mm. Drying and calcination conditions were the same as in Example 1 to obtain alumina support S3 with a K loading of 0.10%.

[0053] Example 4

[0054] Weigh 170g pseudo-boehmite powder, 20g α-Al2O3 powder, 10g alumina trihydrate powder, 6g sesbania powder, and 5g urea, mix them evenly in a mixer, and transfer them to a kneader. The specific surface area of the pseudo-boehmite powder is 257.9m 2 / g, pore volume 1.16ml / g, bulk density 0.23g / ml; α-Al2O3 powder is obtained by calcining high-purity aluminum hydroxide at 1500℃, with an average particle size of 75μm, α-Al2O3 content of 99.5%, and Na, Fe, and Si mass contents of about 0.05%. Same as Example 1. Weigh 2.00g concentrated nitric acid, 1g acetic acid, and 1.517g lanthanum nitrate, add 190g deionized water to prepare a mixed solution. Add the above mixed solution to the evenly mixed powder, knead thoroughly, and then extrude and granulate to obtain spherical particles with a particle size of 4-6mm. The drying conditions are the same as in Example 1, and the calcination procedure is the same as in Example 1, with a calcination temperature of 1180℃ to obtain an alumina carrier S4 with a La loading of 0.35%.

[0055] Example 5

[0056] Weigh 170g of pseudo-boehmite powder, 20g of α-Al2O3 powder, 10g of rapidly dealuminated powder, 6g of sesbania powder, and 6g of starch in a mixer and mix thoroughly. Transfer the mixture to a kneader. The pseudo-boehmite powder has the same physical properties as in Example 1. The α-Al2O3 powder is obtained by calcining high-purity aluminum hydroxide at 1500°C. Ammonium fluoride is added during the calcination process. The resulting α-Al2O3 powder is flaky, with an average particle size of 51μm, an α-Al2O3 content of 99.5%, and approximately 0.05% by weight of Na, Fe, and Si. Weigh 2.00g of concentrated nitric acid, 1g of acetic acid, and 8.936g of magnesium nitrate and add them to 190g of deionized water to prepare a mixed solution. This mixed solution is added to the uniformly mixed powders, kneaded thoroughly, and then extruded and pelletized to produce spherical particles with a diameter of 4-6mm. The drying and calcining conditions were the same as those in Example 4 to obtain an alumina carrier S5 with a Mg loading of 0.60%.

[0057] Comparative Example 1

[0058] Weigh 200g of pseudo-boehmite powder, 8g of sesbania powder, and 4g of starch, mix them evenly in a mixer, and transfer them to a kneader. The specific surface area of the pseudo-boehmite powder is 189.9m 2 / g, pore volume 0.804ml / g, bulk density 0.25g / ml. Weigh 2.80g of concentrated nitric acid and add it to 200g of deionized water to prepare a mixed solution. The mixed solution is added to the uniformly mixed powder, and after thorough kneading, it is extruded and pelletized to obtain spherical particles with a particle size of 4-6mm. The drying conditions are the same as those in Example 1, and the calcination procedure is the same as in Example 1, at a calcination temperature of 1195°C, to obtain alumina support D1.

[0059] Comparative Example 2

[0060] Weigh 196g of pseudo-boehmite powder, 4g of α-Al2O3 powder, 8g of sesbania powder, and 4g of starch, mix them evenly in a mixer, and transfer them to a kneader. The physical properties of the pseudo-boehmite powder and α-Al2O3 powder are the same as those in Example 1. Weigh 2.80g of concentrated nitric acid and 0.174g of lanthanum nitrate, add them to 200g of deionized water to prepare a mixed solution. Add the above mixed solution to the evenly mixed powder, knead it thoroughly, and then extrude it into pellets to obtain spherical particles with a particle size of 4-6mm. The drying and roasting conditions are the same as those in Comparative Example 1 to obtain an alumina carrier D2 with a La loading of 0.04%.

[0061] Comparative Example 3

[0062] Weigh 190g of pseudo-boehmite powder, 10g of α-Al2O3 powder, 8g of sesbania powder, and 4g of starch, mix them evenly in a mixer, and transfer them to a kneader. The pseudo-boehmite powder has the same physical properties as in Comparative Example 1. The α-Al2O3 powder is obtained by calcining ordinary aluminum hydroxide at 1300°C, with an average particle size of 4μm, an α-Al2O3 content of 93.9%, a Si content of 0.2% by mass, and approximately 0.1% by mass of Na and Fe. Weigh 2.80g of concentrated nitric acid and add it to 200g of deionized water to prepare a mixed solution. Add the above mixed solution to the evenly mixed powder, knead thoroughly, and then extrusion-molded and pelletized to obtain spherical particles with a particle size of 4-6mm. The drying and calcination conditions are the same as in Comparative Example 1 to obtain alumina carrier D3.

[0063] The bulk density, strength, water absorption, pore volume and most probable pore diameter of the alumina supports prepared in the above examples and comparative examples were measured. The specific surface area was measured using the nitrogen physical adsorption BET method. The specific surface area of the alumina supports obtained in Examples 1 to 5 was 20 to 50 m 2 / g; bulk density was calculated by measuring the mass of 50ml of alumina support, with each sample measured three times and the average value taken; pore volume and most probable pore diameter were measured by mercury intrusion; water absorption was measured by impregnating the support with deionized water, allowing it to stand for 30 minutes, then pouring off excess deionized water and absorbing any free water on the support surface. The measurement results are shown in Table 1 below.

[0064] Table 1. Physical property measurement results of alumina supports obtained in Examples and Comparative Examples

[0065] serial number Bulk density (g / ml) Strength (Nm) Water absorption (%) Pore volume (ml / g) Most probable pore size (μm) S1 0.569 48.9 65.2 0.70 0.165 S2 0.576 41.9 63.1 0.75 0.168 S3 0.589 53.1 61.2 0.68 0.155 S4 0.610 65.8 57.8 0.63 0.138 S5 0.632 67.1 54.5 0.67 0.143 D1 0.731 83.3 54.5 0.53 0.102 D2 0.749 88.0 49.8 0.62 0.116 D3 0.726 78.0 52.3 0.58 0.121

[0066] According to the data in Table 1, the S1-S5 alumina supports prepared using the method described herein have high water absorption, large pore volume, and large most probable pore diameter, making them advantageous for the preparation of supported metal catalysts. Furthermore, their reduced bulk density allows for a reduced catalyst dosage under the same loading conditions. Although the strength of the alumina supports has decreased, the average strength remains above 40 Nm, sufficient for most catalyst preparations.

[0067] The method for preparing the alumina carrier of the present invention is simple. By adjusting the amount of α-Al2O3 powder added, selecting pseudo-boehmite powder and α-Al2O3 powder with different physical properties, and adjusting the content of other additives during molding, an alumina carrier with low bulk ratio, high water absorption rate and large pore volume can be obtained, which is suitable for the preparation of catalysts in the petrochemical field.

Claims

1. An alumina carrier, characterized in that The water absorption rate of the alumina carrier is 40-70%, the pore volume is 0.6-0.9 ml / g, the most probable pore diameter is 0.165-0.250 μm, and the bulk density is 0.5-0.7 g / ml; the alumina powder used in the preparation of the alumina carrier includes pseudo-boehmite powder, α-Al2O3 powder, and optional trihydrate alumina powder and / or fast-release alumina powder, the α-Al2O3 powder is 5-30wt% of the total weight of the alumina powder, and the particle size of the α-Al2O3 powder is 2-100 μm; the alumina carrier also contains 0.01-1wt% of alkali metal elements, alkaline earth metal elements or rare earth metal elements, and the rare earth metal elements are selected from at least one of La, Ce, Pr, and Y.

2. The alumina carrier according to claim 1, characterized in that The alumina carrier has a water absorption rate of 50-65% and a pore volume of 0.63-0.8 ml / g; and / or, The specific surface area of the alumina carrier is 5 to 120 m 2 / g, strength is 20~200Nm.

3. The alumina carrier according to claim 2, characterized in that The specific surface area of the alumina carrier is 20 to 100 m 2 / g, strength is 30~100Nm.

4. The alumina carrier according to claim 1, characterized in that The alkali metal element is at least one selected from Na, K, and Li; and / or, The alkaline earth metal element is selected from at least one of Mg and Ca.

5. The alumina carrier according to claim 4, characterized in that The rare earth metal element is selected from at least one of La and Ce.

6. A method for preparing the alumina carrier according to any one of claims 1 to 5, comprising the steps of powder mixing, kneading into a shape, and drying and calcining.

7. The preparation method according to claim 6, characterized in that The specific steps include: Step 1: uniformly mix the components including alumina powder and additives to obtain a powder to be kneaded; Step 2: adding the acidic aqueous solution to the powder to be kneaded and kneading into a shape; Step 3: Dry and calcine the kneaded product to obtain the alumina support.

8. The preparation method according to claim 7, characterized in that In step 1: The alumina powder includes pseudo-boehmite powder, α-Al2O3 powder, and optionally alumina trihydrate powder and / or fast-deoxidizing alumina powder; and / or, The auxiliary agent is selected from at least one of silicon-containing compounds and forming pore-forming auxiliary agents.

9. The preparation method according to claim 8, characterized in that The specific surface area of the pseudo-boehmite powder is 200 to 300 m 2 / g, pore volume 0.5-1.2 ml / g, bulk density 0.2-0.4 g / ml; and / or, The α-Al2O3 powder has an α-Al2O3 content greater than 95%, a particle size of 2 to 100 μm, and a mass content of Na, Fe, and Si less than 0.1%; and / or The α-Al2O3 powder is 5 to 30 wt% of the total weight of the alumina powder; and / or, The mass of the alumina trihydrate powder accounts for 0 to 10% of the total mass of the alumina powder; and / or, The mass of the quick-release alumina powder accounts for 0-10% of the total mass of the alumina powder.

10. The preparation method according to claim 9, characterized in that The α-Al2O3 powder accounts for 5 to 20 wt% of the total weight of the alumina powder.

11. The preparation method according to claim 8, characterized in that The silicon-containing compound is selected from water-insoluble silicon-containing compounds; and / or, Calculated by the mass percentage of Si element, the Si element in the silicon-containing compound is 0 to 1.35% of the total weight of the alumina powder; and / or, The forming and pore-forming aid is selected from at least one of natural organic matter, high molecular polymer, and decomposable alkaline compound; and / or, The dosage of the forming pore-forming auxiliary agent is 0-20% of the total mass of the alumina carrier.

12. The preparation method according to claim 11, characterized in that The silicon-containing compound is selected from at least one of dry silica gel, nano silicon oxide, and silicon carbide; and / or, Calculated by the mass percentage of Si element, the Si element in the silicon-containing compound is 0 to 0.9% of the total weight of the alumina powder; and / or, The forming and pore-forming aid is selected from at least one of sesbania powder, starch, methyl cellulose, hydroxypropyl methyl cellulose, sodium hydroxymethyl cellulose, polyethylene microspheres, polystyrene, polyethylene oxide, polyethylene glycol, polyvinyl alcohol, sodium polyacrylate, polyethylene glycol, polyacrylate acrylic acid, urea, methylamine, ethylenediamine, ammonium carbonate, and ammonium bicarbonate; and / or, The dosage of the forming pore-forming auxiliary agent is 0-10% of the total mass of the alumina carrier.

13. The preparation method according to claim 7, characterized in that In step 2: The acid in the acidic aqueous solution is selected from at least one of an organic acid, an inorganic acid, and an acidic salt compound; and / or, The mass percentage concentration of the acid in the acidic aqueous solution is 0.1 to 10%; and / or, The weight ratio of the acidic aqueous solution to the powder to be kneaded is 0.5 to 5:1; and / or, A soluble auxiliary agent is also added to the acidic aqueous solution.

14. The preparation method according to claim 13, characterized in that In step 2: The acid in the acidic aqueous solution is selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, oxalic acid, citric acid, and ammonium dihydrogen phosphate; and / or, The mass percentage concentration of the acid in the acidic aqueous solution is 0.1 to 5%; and / or, The weight ratio of the acidic aqueous solution to the powder to be kneaded is 0.6 to 2:1; and / or, The soluble auxiliary agent is selected from at least one of alkali metal compounds, alkaline earth metal compounds and rare earth metal compounds.

15. The preparation method according to claim 14, characterized in that The acid in the acidic aqueous solution is selected from at least one of nitric acid, acetic acid, oxalic acid and citric acid; and / or, The alkali metal compound is selected from inorganic salt compounds of metals Na, K, and Li; and / or, The alkaline earth metal compound is selected from inorganic salt compounds of metals Mg and Ca; and / or, The rare earth metal compound is selected from soluble rare earth metal salt compounds; and / or, Calculated by the mass percentage of the metal element, the metal in the soluble additive accounts for 0 to 1.35% of the total amount of the aluminum oxide powder.

16. The preparation method according to claim 15, characterized in that The alkali metal compound is selected from at least one of nitrates and chlorides of metals Na, K and Li; and / or The alkaline earth metal compound is selected from at least one of nitrates and chlorides of metal Mg and Ca; and / or The rare earth metal compound is at least one selected from the group consisting of nitrates and chlorides of La, Ce, Pr, and Y; and / or Calculated by the mass percentage of the metal element, the metal in the soluble additive accounts for 0 to 0.9% of the total amount of the aluminum oxide powder.

17. The preparation method according to claim 7, characterized in that In step 3: The drying temperature is 60 to 150° C. and the drying time is 3 to 48 hours; and / or, The calcination temperature is 800-1200° C. and the calcination time is 3-48 hours; and / or, During the calcination process, when the temperature is below 500° C., the heating rate is 30-150° C. / h; when the temperature is above 500° C., the heating rate is 100-280° C. / h.

18. The alumina carrier according to any one of claims 1 to 5 or the alumina carrier prepared by the preparation method according to any one of claims 6 to 17, used for preparing catalysts in the field of petrochemical industry.