Preparation method of low-cost large-pore-volume spherical alumina

Abstract

The application discloses a preparation method of low-cost large-pore-volume spherical alumina, which comprises the following steps: preparing amorphous pseudo-boehmite by using an alcohol aluminum method, preparing micro-sized rod-shaped alumina by simple mechanical grinding and solvent-free crystallization, and finally preparing millimeter-sized spherical alumina by hot oil column forming. The amorphous pseudo-boehmite is subjected to a crystallization reaction at normal temperature without any solvent by using a simple mechanical grinding method, so that the micro-sized rod-shaped pseudo-boehmite is synthesized. The alumina prepared by using the pseudo-boehmite has low impurity content, has a clear micro-sized rod-shaped structure, has high pore volume and mechanical strength, and is suitable for being used as a carrier of an alkane dehydrogenation catalyst and a catalytic reforming catalyst.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of preparation of catalytic materials, and particularly relates to a preparation method of low-cost large-pore-volume spherical alumina. BACKGROUND

[0002] Alumina is a kind of amphoteric metal oxide with excellent performance and stable structure, and has many advantages such as stable structure, strong adsorption, adjustable specific surface area, controllable pore structure, and high mechanical strength, and is widely used as a catalyst, a catalyst carrier, an adsorption material, and a special ceramic material. Industrial applications have certain requirements for the morphology of alumina, and usually require alumina to be made into spherical shape to reduce resistance and friction loss between particles. Spherical alumina has a wide application in fixed bed and fluidized bed processes in chemical production.

[0003] From the microstructure, the millimeter-level spherical alumina is essentially composed of nano- or micro-level primary alumina monomers, and the shape of the alumina monomer fundamentally determines the properties of the spherical alumina carrier. The spherical alumina formed by stacking rod-shaped alumina monomers has open pores, large pore volume, and stable stacking structure, and has high strength, which is an ideal shape of the primary alumina monomer.

[0004] Patent CN 111686751A discloses a preparation method of a catalyst carrier, which is formed by stacking a plurality of nanoscale rod-shaped alumina clusters, and has high pore volume and residual oil hydrogenation activity. Patent CN 110935469A discloses a preparation method of a catalyst carrier, which is formed by stacking microscale rod-shaped alumina monomers, and has a microscale large pore structure, and exhibits high performance in heavy oil hydrogenation catalysis.

[0005] However, the above-mentioned alumina catalyst carriers with rod-shaped primary monomers all use inorganic method to synthesize alumina precursors, and the raw materials introduce many impurities, resulting in insufficient purity of alumina, which cannot be applied to reactions with high requirements for catalyst purity such as propane dehydrogenation and catalytic reforming. Although the organic aluminum alcohol method is used to synthesize alumina precursors, the synthesis process is uncontrollable, and usually requires high-temperature hydrothermal treatment to obtain rod-shaped alumina structure, which has high cost and poor economic benefit.

[0006] In view of the above reasons, the present application provides a preparation method of low-cost large-pore-volume spherical alumina, which uses aluminum alcohol as an aluminum source, first synthesizes a pseudo-boehmite precursor, and then uses mechanical grinding to obtain microscale rod-shaped pseudo-boehmite without solvent. The preparation method can be completed at room temperature, and has low cost, simple operation, low impurity content of the prepared alumina, obvious microscale rod-shaped structure, high mechanical strength and specific surface area, and is suitable for use as a carrier of alkanes dehydrogenation and catalytic reforming catalyst. SUMMARY

[0007] The present application is directed to the problems existing in the preparation of spherical alumina, and provides a preparation method of low-cost large-pore-volume spherical alumina, which has obvious micron-level rod-like structure, low impurity content, high mechanical strength and large pore volume by preparing micron-level rod-like pseudo-boehmite through mechanical grinding without solvent and then preparing large-pore-volume spherical alumina through hot oil column forming.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] A preparation method of low-cost large-pore-volume spherical alumina, which is first to prepare amorphous pseudo-boehmite by using alcohol alumina method, then to prepare micron-level rod-like alumina through simple mechanical grinding without solvent crystallization, and finally to prepare millimeter-level spherical alumina through hot oil column forming; it specifically includes the following steps:

[0010] (1) using organic aluminum alcohol as aluminum source to carry out hydrolysis reaction to prepare amorphous pseudo-boehmite;

[0011] (2) adding structure aid and dispersant to the amorphous pseudo-boehmite prepared in step (1) to mix, and then ultrasonic dispersion to obtain precursor powder with uniform component distribution;

[0012] (3) mechanically grinding the precursor powder obtained in step (2) and aging at room temperature to obtain micron-level rod-like pseudo-boehmite;

[0013] (4) gelatinizing the micron-level rod-like pseudo-boehmite prepared in step (3) and dropping into hot oil column to form gel balls, and then aging, washing, drying and calcining to obtain large-pore-volume spherical alumina.

[0014] Further, the organic aluminum alcohol in step (1) includes one or more of isopropyl alcohol aluminum, sec-butyl alcohol aluminum, n-butyl alcohol aluminum and n-pentyl alcohol aluminum.

[0015] Further, the temperature of the hydrolysis reaction in step (1) is 20-80℃, and the time is 2-8h.

[0016] Further, the structure aid in step (2) includes one or more of ammonium bicarbonate, cetyltrimethylammonium bromide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and N,N-dimethylformamide, and the amount is converted according to the N / Al molar ratio of 0.05-0.5 with the amorphous pseudo-boehmite.

[0017] Further, the dispersant in step (2) includes one or more of stearic acid, oleic acid, polyvinyl alcohol and polyacrylic acid, and the amount is 0.2-2% of the mass of the amorphous pseudo-boehmite.

[0018] Further, the mechanical grinding in step (3) adopts horizontal ball milling or planetary ball milling.

[0019] Further, when the horizontal ball milling is adopted, the ball milling jar is made of polytetrafluoroethylene, the ball milling beads are made of yttria-stabilized zirconia ceramic material, the diameter is 1-5 mm, the volume filling rate of the material is 35%-65%, the ball milling speed is 15-75 r / min, and the ball milling time is 24-120 h.

[0020] Further, when the planetary ball milling is adopted, the ball milling jar is made of polytetrafluoroethylene, the ball milling beads are made of yttria-stabilized zirconia ceramic material, the diameter is 0.3-3 mm, the volume filling rate of the material is 35%-65%, the ball milling speed is 100-250 r / min, and the ball milling time is 12-48 h.

[0021] Further, the aging time in step (3) is 24-48 h.

[0022] The present application has the following advantages:

[0023] (1) The present application provides a preparation method of low-cost large-pore-volume spherical alumina, which adopts an alcohol alumina method to prepare amorphous pseudo-boehmite, a mechanical grinding method to prepare micron-level rod-shaped pseudo-boehmite without solvent crystallization, and finally a hot oil column method to prepare spherical alumina. The prepared alumina has low impurity content, has a clear micron-level rod-shaped structure, solves the problems of high impurity content of alumina prepared by inorganic salt method, poor controllability of alcohol alumina hydrolysis method, high cost of preparing specific morphology pseudo-boehmite, and low economic benefit, and has high mechanical strength and specific surface area, excellent industrial production value and economic benefit.

[0024] (2) The mechanical grinding solvent-free method used in the present application can complete the crystallization reaction at room temperature, has the advantages of convenient operation, low energy consumption, and no need for complex post-treatment process, and has obvious cost advantage. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The scanning electron microscope images of the pseudo-boehmite obtained in Example 4 (a) and Comparative Examples 1 (b) and 2 (c). As shown in the figures, the pseudo-boehmite prepared by not performing ball milling crystallization treatment and by using different structural additives in combination with ball milling crystallization treatment has obvious differences in morphology, and the morphology of the pseudo-boehmite can be guided by using a simple mechanical grinding crystallization method and adding specific structural additives to prepare micron-level rod-shaped pseudo-boehmite.

[0026] Figure 2The scanning electron microscope images of the pseudo-boehmite obtained by different ball milling methods are shown in Figure 1, wherein Figure 1(a) is the image of the pseudo-boehmite obtained in Example 4 (planetary ball milling) and Figure 1(b) is the image of the pseudo-boehmite obtained in Example 9 (horizontal ball milling). As can be seen from the images, the rod-like characteristics of the pseudo-boehmite prepared by the planetary ball milling method are obviously better than those of the pseudo-boehmite prepared by the horizontal ball milling method.

[0027] Figure 3 The scanning electron microscope images of the pseudo-boehmite obtained by different ball milling speeds are shown in Figure 2, wherein Figure 2(a) is the image of the pseudo-boehmite obtained in Example 10 (100 r / min), Figure 2(b) is the image of the pseudo-boehmite obtained in Example 11 (150 r / min), Figure 2(c) is the image of the pseudo-boehmite obtained in Example 4 (200 r / min), and Figure 2(d) is the image of the pseudo-boehmite obtained in Example 12 (250 r / min). As can be seen from the images, the rod-like characteristics of the pseudo-boehmite prepared by the ball milling speed of 200 r / min are the most obvious.

[0028] Figure 4 The scanning electron microscope images of the pseudo-boehmite obtained by different ball milling times are shown in Figure 3, wherein Figure 3(a) is the image of the pseudo-boehmite obtained in Example 13 (12 h), Figure 3(b) is the image of the pseudo-boehmite obtained in Example 4 (24 h), Figure 3(c) is the image of the pseudo-boehmite obtained in Example 14 (36 h), and Figure 3(d) is the image of the pseudo-boehmite obtained in Example 15 (48 h). As can be seen from the images, the rod-like characteristics of the pseudo-boehmite prepared by the ball milling time of 24 h are the most obvious. DETAILED DESCRIPTION

[0029] A method for preparing low-cost spherical alumina with large pore volume, comprising the following steps:

[0030] (1) adding isopropyl alcohol and water into organic aluminum alcohol at a molar ratio of 1:3.6:7, hydrolyzing at 20-80 °C for 2-8 h, and then performing suction filtration and drying to obtain amorphous pseudo-boehmite;

[0031] (2) mixing a structure aid and a dispersant with the amorphous pseudo-boehmite obtained in step (1), and then performing ultrasonic dispersion to obtain a precursor powder with uniform component distribution;

[0032] (3) mechanically grinding the precursor powder obtained in step (2) by horizontal ball milling or planetary ball milling, and then aging at room temperature for 24-48 h to obtain micron-sized rod-like pseudo-boehmite;

[0033] (4) sol-gel dissolving the micron-sized rod-like pseudo-boehmite obtained in step (3), dropping the sol-gel into a hot oil column to form gel beads, and then performing aging, washing, drying, and calcination to obtain spherical alumina with large pore volume.

[0034] In step (1), the organic aluminum alcohol includes one or more of isopropyl aluminum alcohol, sec-butyl aluminum alcohol, n-butyl aluminum alcohol, and n-pentyl aluminum alcohol.

[0035] The structure aid in step (2) includes one or more of ammonium bicarbonate, cetyltrimethylammonium bromide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and N,N-dimethylformamide, and the amount is converted to 0.05-0.5 N / Al molar ratio of the amorphous pseudoboehmite. The dispersant includes one or more of stearic acid, oleic acid, polyvinyl alcohol, and polyacrylic acid, and the amount is 0.2-2% of the mass of the amorphous pseudoboehmite.

[0036] In step (3), when a horizontal ball mill is used, the ball mill tank is made of polytetrafluoroethylene, the ball mill beads are made of yttria-stabilized zirconia ceramic, the diameter is 1-5 mm, the volume filling rate of the material is 35%-65%, the ball mill rotation speed is 15-75 r / min, and the ball mill time is 24-120 h. When a planetary ball mill is used, the ball mill tank is made of polytetrafluoroethylene, the ball mill beads are made of yttria-stabilized zirconia ceramic, the diameter is 0.3-3 mm, the volume filling rate of the material is 35%-65%, the ball mill rotation speed is 100-250 r / min, and the ball mill time is 12-48 h.

[0037] In order to make the content of the present application more convenient to understand, the technical solutions of the present application are further described below in combination with specific embodiments, but the present application is not limited thereto.

[0038] Example 1

[0039] (1) Preparation of amorphous pseudoboehmite: 75 g of aluminum isopropoxide was added to a three-necked flask, isopropyl alcohol and high-purity water were added according to the molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, 80 ℃ reflux stirring for 4 h, after filtration, 100 ℃ drying, to obtain amorphous pseudoboehmite;

[0040] (2) Mechanical grinding and crystal transformation to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite was mixed with 1.2406 g of ammonium bicarbonate and 0.24 g of stearic acid in a V-type mixer for 30 min, then placed in an ultrasonic cleaner for ultrasonic treatment for 60 min, then the uniformly mixed powder was placed in a ball mill tank, filled to 60% of the tank volume, then 3 mm diameter ball mill beads were added, then the ball mill tank was placed on a planetary ball mill, the ball mill rotation speed was set to 200 r / min, and the ball mill time was 24 h. After ball milling, the powder and ball mill beads were separated by using a vibrating screen, and the obtained powder was aged and dried at room temperature for 24 h to obtain micron-sized rod-like pseudoboehmite;

[0041] (3) Forming: 50 g of the prepared micron-sized rod-like pseudoboehmite was taken, 124.4 g of water was added according to the 75% aluminum oxide content, and a 20 wt.% sol was prepared; after stirring for 30 min, 6.9 g of 20 wt.% nitric acid solution was added dropwise, so that the acid-aluminum ratio (H+ The mixture was stirred for 30 min, and then 5.7 g of a 35 wt.% hexamethylenetetramine solution was added and stirred for 10 min to form a sol with a certain viscosity. The sol was dripped into hot oil at 110°C using a needle, and the formed gel beads were aged in the hot oil for 16 h. After washing with petroleum ether, the gel beads were placed in an oven at 80°C and dried for 24 h, and then calcined at 1000°C for 4 h to obtain spherical alumina products. The physical property parameters of the products are listed in Table 1.

[0042] Example 2

[0043] (1) Preparation of amorphous pseudoboehmite: 75 g of aluminum isopropoxide was added to a three-necked flask, and isopropyl alcohol and high-purity water were added according to a molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7. The mixture was stirred at 80°C for 4 h, and then filtered and dried at 100°C to obtain amorphous pseudoboehmite;

[0044] (2) Mechanical grinding and crystal transformation to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite, 5.7215 g of tetramethylammonium hydroxide, and 0.24 g of stearic acid were mixed in a V-type mixer for 30 min, and then placed in an ultrasonic cleaner for ultrasonic treatment for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and then 3 mm diameter ball milling beads were added. The ball milling tank was then placed in a planetary ball mill, and the ball milling speed was set to 200 r / min. The ball milling time was 24 h. After ball milling, the powder and ball milling beads were separated by using a vibrating screen, and the obtained powder was air-dried at room temperature for 24 h to obtain micron-sized rod-like pseudoboehmite;

[0045] (3) Shaping: 50 g of the prepared micron-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%. After stirring for 30 min, 6.9 g of a 20 wt.% nitric acid solution was added dropwise to form a sol with an acid-alumina ratio (H + The mixture was stirred for 30 min, and then 5.7 g of a 35 wt.% hexamethylenetetramine solution was added and stirred for 10 min to form a sol with a certain viscosity. The sol was dripped into hot oil at 110°C using a needle, and the formed gel beads were aged in the hot oil for 16 h. After washing with petroleum ether, the gel beads were placed in an oven at 80°C and dried for 24 h, and then calcined at 1000°C for 4 h to obtain spherical alumina products. The physical property parameters of the products are listed in Table 1.

[0046] Example 3

[0047] (1) Preparation of amorphous pseudoboehmite: 75 g aluminum isopropoxide was added into a three-necked flask, isopropyl alcohol and high-purity water were added according to the molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirred at 80 °C for 4 h. After filtration, it was dried at 100 °C to obtain amorphous pseudoboehmite;

[0048] (2) Mechanical grinding and crystal transformation to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite, 9.2435 g of tetraethylammonium hydroxide, and 0.24 g of stearic acid were mixed in a V-type mixer for 30 min, and then placed in an ultrasonic cleaner for ultrasonic treatment for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and 3 mm diameter ball milling beads were added. Then the ball milling tank was placed in a planetary ball mill, and the ball milling speed was set to 200 r / min, and the ball milling time was 24 h. After ball milling, the powder and ball milling beads were separated by using a vibrating screen, and the obtained powder was aged and dried at room temperature for 24 h to prepare micron-sized rod-like pseudoboehmite;

[0049] (3) Shaping: 50 g of micron-sized rod-like pseudoboehmite was prepared, and 124.4 g of water was added according to an alumina content of 75% to prepare a 20 wt.% sol. After stirring for 30 min, 6.9 g of 20 wt.% nitric acid solution was added dropwise to make the molar ratio of aluminum to Al2O3 (H + / Al2O3) 0.06, and stirred for 30 min. Then 5.7 g of 35 wt.% hexamethylenetetramine solution was added and stirred for 10 min to form a sol with certain viscosity. The sol was dropped into hot oil at 110 °C through a needle, and the formed gel beads were aged in the hot oil for 16 h. After washing with petroleum ether, they were placed in an oven at 80 °C for drying for 24 h, and then calcined at 1000 °C for 4 h to obtain spherical alumina products. The physical property parameters are listed in Table 1.

[0050] Example 4

[0051] (1) Preparation of amorphous pseudoboehmite: 75 g aluminum isopropoxide was added into a three-necked flask, isopropyl alcohol and high-purity water were added according to the molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirred at 80 °C for 4 h. After filtration, it was dried at 100 °C to obtain amorphous pseudoboehmite;

[0052] (2) Mechanical grinding to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite was mixed with 0.5763 g of N,N-dimethylformamide and 0.24 g of stearic acid in a V-type mixer for 30 min, and then was placed in an ultrasonic cleaner for ultrasonic treatment for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and then 3 mm diameter ball milling beads were added. The ball milling tank was then placed on a planetary ball mill, and the ball milling speed was set to 200 r / min, and the ball milling time was 24 h. After the ball milling was completed, the powder and the ball milling beads were separated by using a vibrating screen, and the obtained powder was aged and air-dried at room temperature for 24 h to prepare micrometer-sized rod-like pseudoboehmite;

[0053] (3) Shaping: 50 g of the prepared micrometer-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%. After stirring for 30 min, 6.9 g of 20 wt.% nitric acid solution was added dropwise to make the acid-aluminum molar ratio (H + / Al2O3) 0.06, and stirring was performed for 30 min. Then, 5.7 g of 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity. The sol was dropped into hot oil at 110°C through a needle to form gel beads, which were aged in the hot oil for 16 h, and then were washed with petroleum ether and placed in an oven at 80°C for drying for 24 h, and then were calcined at 1000°C for 4 h to obtain a spherical alumina product. The physical property parameters of the product are listed in Table 1.

[0054] Example 5

[0055] (1) Preparation of amorphous pseudoboehmite: 75 g of aluminum isopropoxide was added to a three-necked flask, and isopropyl alcohol and high-purity water were added according to a molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7. Stirring was performed at 80°C for 4 h, and then the mixture was filtered and dried at 100°C to obtain amorphous pseudoboehmite;

[0056] (2) Mechanical grinding to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite was mixed with 1.1527 g of N,N-dimethylformamide and 0.24 g of stearic acid in a V-type mixer for 30 min, and then was placed in an ultrasonic cleaner for ultrasonic treatment for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and then 3 mm diameter ball milling beads were added. The ball milling tank was then placed on a planetary ball mill, and the ball milling speed was set to 200 r / min, and the ball milling time was 24 h. After the ball milling was completed, the powder and the ball milling beads were separated by using a vibrating screen, and the obtained powder was aged and air-dried at room temperature for 24 h to prepare micrometer-sized rod-like pseudoboehmite;

[0057] (3) Forming: 50 g of the prepared micron-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%; after stirring for 30 min, 6.9 g of a 20 wt.% nitric acid solution was added dropwise so that the acid-to-alumina ratio (H + to Al203) was 0.06, and stirring was performed for 30 min; then, 5.7 g of a 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity; the sol was dripped into hot oil at 110°C using a needle, the formed gel beads were aged in the hot oil for 16 h, and then washed with petroleum ether and placed in an oven at 80°C for drying for 24 h; the product was calcined at 1000°C for 4 h to obtain a spherical alumina product, and the physical property parameters of the product are listed in Table 1.

[0058] Example 6

[0059] (1) Preparation of amorphous pseudoboehmite: 75 g of aluminum isopropoxide was added to a three-necked flask, and isopropyl alcohol and high-purity water were added according to a molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirring was performed at 80°C under reflux for 4 h; after filtration, drying was performed at 100°C to obtain amorphous pseudoboehmite;

[0060] (2) Preparation of rod-like pseudoboehmite by mechanical grinding and crystal transformation: 8 g of amorphous pseudoboehmite, 2.3054 g of N,N-dimethylformamide, and 0.24 g of stearic acid were mixed in a V-type mixer for 30 min, and then placed in an ultrasonic cleaner for ultrasonic treatment for 60 min; the uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and then 3-mm-diameter ball milling beads were added; the ball milling tank was then placed on a planetary ball mill, and the ball milling speed was set to 200 r / min, and the ball milling time was set to 24 h; after the ball milling was completed, the powder and the ball milling beads were separated by using a vibrating screen, and the obtained powder was air-dried at room temperature for 24 h to obtain micron-sized rod-like pseudoboehmite;

[0061] (3) Forming: 50 g of the prepared micron-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%; after stirring for 30 min, 6.9 g of a 20 wt.% nitric acid solution was added dropwise so that the acid-to-alumina ratio (H + to Al203) was 0.06, and stirring was performed for 30 min; then, 5.7 g of a 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity; the sol was dripped into hot oil at 110°C using a needle, the formed gel beads were aged in the hot oil for 16 h, and then washed with petroleum ether and placed in an oven at 80°C for drying for 24 h; the product was calcined at 1000°C for 4 h to obtain a spherical alumina product, and the physical property parameters of the product are listed in Table 1.

[0062] Example 7

[0063] (1) Preparation of amorphous pseudoboehmite: 75 g aluminum isopropoxide was added into a three-necked flask, isopropyl alcohol and high-purity water were added according to the molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirred at 80°C for 4 h. After suction filtration, drying was performed at 100°C to obtain amorphous pseudoboehmite;

[0064] (2) Mechanical grinding and crystal transformation to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite, 3.4582 g of N,N-dimethylformamide, and 0.24 g of stearic acid were mixed in a V-type mixer for 30 min, and then ultrasonic treatment was performed in an ultrasonic cleaner for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and 3 mm diameter ball milling beads were added. Then, the ball milling tank was placed in a planetary ball mill, and the ball milling speed was set to 200 r / min. The ball milling time was 24 h. After ball milling, the powder and ball milling beads were separated by using a vibrating screen, and the obtained powder was aged and air-dried at room temperature for 24 h to obtain micron-sized rod-like pseudoboehmite;

[0065] (3) Shaping: 50 g of the prepared micron-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added according to an alumina content of 75% to prepare a 20 wt.% sol. After stirring for 30 min, 6.9 g of a 20 wt.% nitric acid solution was added dropwise to make the molar ratio of aluminum to Al2O3 (H + / Al2O3) 0.06, and stirring was performed for 30 min. Then, 5.7 g of a 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity. The sol was dropped into hot oil at 110°C using a needle, and the formed gel beads were aged in the hot oil for 16 h. After washing with petroleum ether, the gel beads were placed in an oven at 80°C for drying for 24 h, and then calcination was performed at 1000°C for 4 h to obtain a spherical alumina product. The physical property parameters of the product are shown in Table 1.

[0066] Example 8

[0067] (1) Preparation of amorphous pseudoboehmite: 75 g aluminum isopropoxide was added into a three-necked flask, isopropyl alcohol and high-purity water were added according to the molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirred at 80°C for 4 h. After suction filtration, drying was performed at 100°C to obtain amorphous pseudoboehmite;

[0068] (2) Mechanical grinding to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite was mixed with 5.7636 g of N,N-dimethylformamide and 0.24 g of stearic acid in a V-type mixer for 30 min, and then was placed in an ultrasonic cleaner for ultrasonic treatment for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and then 3 mm diameter ball milling beads were added. The ball milling tank was then placed in a planetary ball mill, and the ball milling speed was set to 200 r / min, and the ball milling time was 24 h. After the ball milling was completed, the powder and the ball milling beads were separated by using a vibrating screen, and the obtained powder was aged and air-dried at room temperature for 24 h to prepare micrometer-sized rod-like pseudoboehmite;

[0069] (3) Shaping: 50 g of the prepared micrometer-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%. After stirring for 30 min, 6.9 g of 20 wt.% nitric acid solution was added dropwise to make the acid-aluminum ratio (H + Al2O3) 0.06, and stirring was performed for 30 min. Then, 5.7 g of 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity. The sol was dropped into hot oil at 110°C using a needle, and the obtained gel beads were aged in the hot oil for 16 h. After being washed with petroleum ether, the gel beads were placed in an oven at 80°C for drying for 24 h, and were calcined at 1000°C for 4 h to obtain a spherical alumina product. The physical property parameters of the product are listed in Table 1.

[0070] Example 9

[0071] (1) Preparation of amorphous pseudoboehmite: 75 g of aluminum isopropoxide was added to a three-necked flask, and isopropyl alcohol and high-purity water were added according to a molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7. Stirring was performed at 80°C for 4 h, and then the product was filtered and dried at 100°C to obtain amorphous pseudoboehmite;

[0072] (2) Mechanical grinding to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite was mixed with 0.5763 g of N,N-dimethylformamide and 0.24 g of stearic acid in a V-type mixer for 30 min, and then was placed in an ultrasonic cleaner for ultrasonic treatment for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and then 5 mm diameter ball milling beads were added. The ball milling tank was then placed in a horizontal ball mill, and the ball milling speed was set to 60 r / min, and the ball milling time was 24 h. After the ball milling was completed, the powder and the ball milling beads were separated by using a vibrating screen, and the obtained powder was aged and air-dried at room temperature for 24 h to prepare micrometer-sized rod-like pseudoboehmite;

[0073] (3) Forming: 50 g of the prepared micron-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%; after stirring for 30 min, 6.9 g of a 20 wt.% nitric acid solution was added dropwise so that the acid-to-alumina ratio (H + to Al203) was 0.06, and stirring was performed for 30 min; then, 5.7 g of a 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity; the sol was dripped into hot oil at 110°C using a needle, the formed gel beads were aged in the hot oil for 16 h, and then washed with petroleum ether and placed in an oven at 80°C for drying for 24 h; the product was calcined at 1000°C for 4 h to obtain a spherical alumina product, and the physical property parameters of the product are listed in Table 1.

[0074] Example 10

[0075] (1) Preparation of amorphous pseudoboehmite: 75 g of aluminum isopropoxide was added to a three-necked flask, and isopropyl alcohol and high-purity water were added according to a molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirring was performed at 80°C under reflux for 4 h; after filtration, drying was performed at 100°C to obtain amorphous pseudoboehmite;

[0076] (2) Preparation of rod-like pseudoboehmite by mechanical grinding and crystal transformation: 8 g of amorphous pseudoboehmite, 0.5763 g of N,N-dimethylformamide, and 0.24 g of stearic acid were mixed in a V-type mixer for 30 min, and then placed in an ultrasonic cleaner for ultrasonic treatment for 60 min; the uniformly mixed powder was placed in a ball milling tank, filled to 60% of the volume of the tank, and then 3-mm-diameter ball milling beads were added; the ball milling tank was then placed on a planetary ball mill, and the ball milling speed was set to 100 r / min, and the ball milling time was set to 24 h; after the ball milling was completed, the powder and the ball milling beads were separated by using a vibrating screen, and the obtained powder was air-dried at room temperature for 24 h to obtain micron-sized rod-like pseudoboehmite;

[0077] (3) Forming: 50 g of the prepared micron-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%; after stirring for 30 min, 6.9 g of a 20 wt.% nitric acid solution was added dropwise so that the acid-to-alumina ratio (H + to Al203) was 0.06, and stirring was performed for 30 min; then, 5.7 g of a 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity; the sol was dripped into hot oil at 110°C using a needle, the formed gel beads were aged in the hot oil for 16 h, and then washed with petroleum ether and placed in an oven at 80°C for drying for 24 h; the product was calcined at 1000°C for 4 h to obtain a spherical alumina product, and the physical property parameters of the product are listed in Table 1.

[0078] Example 11

[0079] (1) Preparation of amorphous pseudoboehmite: 75 g aluminum isopropoxide was added into a three-necked flask, isopropyl alcohol and high-purity water were added according to the molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirred at 80°C for 4 h. After suction filtration, drying was performed at 100°C to obtain amorphous pseudoboehmite;

[0080] (2) Mechanical grinding and crystal transformation to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite, 0.5763 g of N,N-dimethylformamide, and 0.24 g of stearic acid were mixed in a V-type mixer for 30 min, and then ultrasonic treatment was performed in an ultrasonic cleaner for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and 3 mm diameter ball milling beads were added. Then, the ball milling tank was placed in a planetary ball mill, and the ball milling speed was set to 150 r / min. The ball milling time was 24 h. After ball milling, the powder and ball milling beads were separated by using a vibrating screen, and the obtained powder was aged and air-dried at room temperature for 24 h to obtain micrometer-sized rod-like pseudoboehmite;

[0081] (3) Shaping: 50 g of the prepared micrometer-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an aluminum oxide content of 75%. After stirring for 30 min, 6.9 g of a 20 wt.% nitric acid solution was added dropwise to make the molar ratio of aluminum to Al2O3 (H + / Al2O3) 0.06, and stirring was performed for 30 min. Then, 5.7 g of a 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity. The sol was dropped into hot oil at 110°C through a needle to form gel beads, which were aged in the hot oil for 16 h. After washing with petroleum ether, the gel beads were placed in an oven at 80°C for drying for 24 h, and then calcination was performed at 1000°C for 4 h to obtain a spherical aluminum oxide product. The physical property parameters of the product are shown in Table 1.

[0082] Example 12

[0083] (1) Preparation of amorphous pseudoboehmite: 75 g aluminum isopropoxide was added into a three-necked flask, isopropyl alcohol and high-purity water were added according to the molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirred at 80°C for 4 h. After suction filtration, drying was performed at 100°C to obtain amorphous pseudoboehmite;

[0084] (2) Mechanical grinding to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite was mixed with 0.5763 g of N,N-dimethylformamide and 0.24 g of stearic acid in a V-type mixer for 30 min, and then was placed in an ultrasonic cleaner for ultrasonic treatment for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and 3 mm diameter ball milling beads were added. Then the ball milling tank was placed on a planetary ball mill, and the ball milling speed was set to 250 r / min, and the ball milling time was 24 h. After ball milling, the powder and the ball milling beads were separated by using a vibrating screen, and the obtained powder was aged and air-dried at room temperature for 24 h to prepare micrometer-sized rod-like pseudoboehmite;

[0085] (3) Shaping: 50 g of the prepared micrometer-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%. After stirring for 30 min, 6.9 g of 20 wt.% nitric acid solution was added dropwise to make the acid-aluminum ratio (H + / Al2O3) 0.06, and stirring was performed for 30 min. Then 5.7 g of 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity. The sol was dropped into hot oil at 110°C through a needle to form gel beads, which were aged in the hot oil for 16 h. After washing with petroleum ether, the gel beads were placed in an oven at 80°C for drying for 24 h, and were calcined at 1000°C for 4 h to obtain spherical alumina products. The physical property parameters of the products are listed in Table 1.

[0086] Example 13

[0087] (1) Preparation of amorphous pseudoboehmite: 75 g of aluminum isopropoxide was added to a three-necked flask, and isopropyl alcohol and high-purity water were added according to a molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7. Stirring was performed at 80°C for 4 h, and then the mixture was filtered and dried at 100°C to obtain amorphous pseudoboehmite;

[0088] (2) Mechanical grinding to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite was mixed with 0.5763 g of N,N-dimethylformamide and 0.24 g of stearic acid in a V-type mixer for 30 min, and then was placed in an ultrasonic cleaner for ultrasonic treatment for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and 3 mm diameter ball milling beads were added. Then the ball milling tank was placed on a planetary ball mill, and the ball milling speed was set to 250 r / min, and the ball milling time was 24 h. After ball milling, the powder and the ball milling beads were separated by using a vibrating screen, and the obtained powder was aged and air-dried at room temperature for 24 h to prepare micrometer-sized rod-like pseudoboehmite;

[0089] (3) Forming: 50 g of the prepared micron-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%; after stirring for 30 min, 6.9 g of a 20 wt.% nitric acid solution was added dropwise so that the acid-to-alumina ratio (H + to Al203) was 0.06, and stirring was performed for 30 min; then, 5.7 g of a 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity; the sol was dripped into hot oil at 110°C using a needle, the formed gel beads were aged in the hot oil for 16 h, and then washed with petroleum ether and placed in an oven at 80°C for drying for 24 h; the product was calcined at 1000°C for 4 h to obtain a spherical alumina product, and the physical property parameters of the product are listed in Table 1.

[0090] Example 14

[0091] (1) Preparation of amorphous pseudoboehmite: 75 g of aluminum isopropoxide was added to a three-necked flask, and isopropyl alcohol and high-purity water were added according to a molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirring was performed at 80°C under reflux for 4 h; after filtration, drying was performed at 100°C to obtain amorphous pseudoboehmite;

[0092] (2) Preparation of rod-like pseudoboehmite by mechanical grinding and crystal transformation: 8 g of amorphous pseudoboehmite, 0.5763 g of N,N-dimethylformamide, and 0.24 g of stearic acid were mixed in a V-type mixer for 30 min, and then placed in an ultrasonic cleaner for ultrasonic treatment for 60 min; the uniformly mixed powder was placed in a ball milling tank, filled to 60% of the volume of the tank, and then 3-mm-diameter ball milling beads were added; the ball milling tank was then placed on a planetary ball mill, and the ball milling speed was set to 200 r / min, and the ball milling time was 36 h; after the ball milling was completed, the powder and the ball milling beads were separated by using a vibrating screen, and the obtained powder was air-dried at room temperature for 24 h to obtain micron-sized rod-like pseudoboehmite;

[0093] (3) Forming: 50 g of the prepared micron-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%; after stirring for 30 min, 6.9 g of a 20 wt.% nitric acid solution was added dropwise so that the acid-to-alumina ratio (H + to Al203) was 0.06, and stirring was performed for 30 min; then, 5.7 g of a 35 wt.% hexamethylenetetramine solution was added, and stirring was performed for 10 min to form a sol with a certain viscosity; the sol was dripped into hot oil at 110°C using a needle, the formed gel beads were aged in the hot oil for 16 h, and then washed with petroleum ether and placed in an oven at 80°C for drying for 24 h; the product was calcined at 1000°C for 4 h to obtain a spherical alumina product, and the physical property parameters of the product are listed in Table 1.

[0094] Example 15

[0095] (1) Preparation of amorphous pseudoboehmite: 75 g aluminum isopropoxide was added into a three-necked flask, isopropyl alcohol and high-purity water were added according to the molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirred at 80°C for 4 h. After filtration, it was dried at 100°C to obtain amorphous pseudoboehmite;

[0096] (2) Mechanical grinding and crystal transformation to prepare rod-like pseudoboehmite: 8 g of amorphous pseudoboehmite, 0.5763 g of N,N-dimethylformamide and 0.24 g of stearic acid were mixed in a V-type mixer for 30 min, and then were placed in an ultrasonic cleaner for ultrasonic treatment for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and then 3 mm diameter ball milling beads were added. The ball milling tank was placed in a planetary ball mill, and the ball milling speed was set to 200 r / min. The ball milling time was 48 h. After ball milling, the powder and ball milling beads were separated by using a vibrating screen. The obtained powder was aged and air-dried at room temperature for 24 h to obtain micrometer-sized rod-like pseudoboehmite;

[0097] (3) Shaping: 50 g of the prepared micrometer-sized rod-like pseudoboehmite was taken, and 124.4 g of water was added according to the aluminum oxide content of 75% to prepare a 20 wt.% sol. After stirring for 30 min, 6.9 g of 20 wt.% nitric acid solution was added dropwise to make the acid-aluminum ratio (H + / Al2O3) 0.06, and stirred for 30 min. Then, 5.7 g of 35 wt.% hexamethylenetetramine solution was added, and stirred for 10 min to form a sol with certain viscosity. The sol was dropped into hot oil at 110°C through a needle to form gel beads, which were aged in the hot oil for 16 h. After washing with petroleum ether, the gel beads were placed in an oven at 80°C for drying for 24 h, and then were calcined at 1000°C for 4 h to obtain spherical aluminum oxide products. The physical property parameters are shown in Table 1.

[0098] Comparative Example 1

[0099] (1) Preparation of amorphous pseudoboehmite: 75 g aluminum isopropoxide was added into a three-necked flask, isopropyl alcohol and high-purity water were added according to the molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirred at 80°C for 4 h. After filtration, it was dried at 100°C to obtain amorphous pseudoboehmite;

[0100] (3) Shaping: 50 g of the prepared amorphous pseudoboehmite was taken, and 124.4 g of water was added according to the aluminum oxide content of 75% to prepare a 20 wt.% sol. After stirring for 30 min, 6.9 g of 20 wt.% nitric acid solution was added dropwise to make the acid-aluminum ratio (H +The molar ratio of Al2O3) is 0.06, stirring for 30 min; then add 5.7 g of 35 wt.% hexamethyl tetramine solution, stirring for 10 min to form a sol with certain viscosity, drop the sol into hot oil at 110 ℃ with a needle, the formed gel beads are aged in hot oil for 16 h, then washed with petroleum ether and placed in an oven at 80 ℃ for drying for 24 h, and then calcined at 1000 ℃ for 4 h to obtain a spherical alumina product, and the physical property parameters of which are listed in Table 1.

[0101] Comparative Example 2

[0102] (1) Preparation of amorphous pseudoboehmite: 75 g of aluminum isopropoxide is added to a three-necked flask, isopropyl alcohol and high-purity water are added according to the molar ratio of aluminum isopropoxide to isopropyl alcohol and water of 1:3.6:7, and stirred at 80 ℃ for 4 h. After filtration, it is dried at 100 ℃ to obtain amorphous pseudoboehmite;

[0103] (2) Mechanical grinding and crystal transformation to prepare blocky pseudoboehmite: 8 g of amorphous pseudoboehmite is mixed with 0.6905 g of polyethylene glycol (800) and 0.24 g of stearic acid in a V-type mixer for 30 min, and then placed in an ultrasonic cleaner for ultrasonic treatment for 60 min. The uniformly mixed powder is placed in a ball milling tank, filled to 60% of the tank volume, and then 3 mm diameter ball milling beads are added. Then the ball milling tank is placed on a planetary ball mill, and the ball milling speed is set to 200 r / min, and the ball milling time is 24 h. After ball milling, the powder and ball milling beads are separated by using a vibrating screen, and the obtained powder is aged and air-dried at room temperature for 24 h to obtain micrometer-sized rod-like pseudoboehmite;

[0104] (3) Shaping: 50 g of the prepared micrometer-sized rod-like pseudoboehmite is taken, and 124.4 g of water is added to prepare a 20 wt.% sol according to an alumina content of 75%; after stirring for 30 min, 6.9 g of 20 wt.% nitric acid solution is added dropwise to make the acid-alumina ratio (H + The molar ratio of Al2O3) is 0.06, stirring for 30 min; then add 5.7 g of 35 wt.% hexamethyl tetramine solution, stirring for 10 min to form a sol with certain viscosity, drop the sol into hot oil at 110 ℃ with a needle, the formed gel beads are aged in hot oil for 16 h, then washed with petroleum ether and placed in an oven at 80 ℃ for drying for 24 h, and then calcined at 1000 ℃ for 4 h to obtain a spherical alumina product, and the physical property parameters of which are listed in Table 1.

[0105] Comparative Example 3

[0106] (1) Synthesis of amorphous pseudo-boehmite by inorganic method: a certain amount of sodium metaaluminate was prepared into a sodium metaaluminate solution with a concentration of 1.2 M, and then the solution was dropped into a three-necked flask with a condenser at a flow rate of 3 mL / min, and the three-necked flask was placed in an 80 ℃ oil bath. The dropping rate was adjusted to ensure that the pH value of the mixed solution was 8. After the solution was completely added, the constant temperature reaction was continued for 3 h, and then the completely aged solution was filtered to obtain a wet filter cake which was dried at 60 ℃ for 12 h to obtain amorphous pseudo-boehmite.

[0107] (2) Preparation of rod-like pseudo-boehmite by mechanical grinding and crystal transformation: 8 g of amorphous pseudo-boehmite, 0.5763 g of N,N-dimethylformamide and 0.24 g of stearic acid were mixed in a V-type mixer for 30 min, and then ultrasonic treatment was carried out in an ultrasonic cleaner for 60 min. The uniformly mixed powder was placed in a ball milling tank, filled to 60% of the tank volume, and then 3 mm diameter ball milling beads were added. Then the ball milling tank was placed in a planetary ball mill, and the ball milling speed was set to 200 r / min, and the ball milling time was 24 h. After ball milling, the powder and ball milling beads were separated by using a vibrating screen, and the obtained powder was aged and air-dried at room temperature for 24 h to obtain micron-sized rod-like pseudo-boehmite;

[0108] (3) Shaping: 50 g of rod-like pseudo-boehmite prepared by the inorganic method was taken, and 124.4 g of water was added to prepare a 20 wt.% sol according to an alumina content of 75%. After stirring for 30 min, 6.9 g of 20 wt.% nitric acid solution was added dropwise to make the molar ratio of acid to alumina (H + / Al2O3) 0.06, and stirred for 30 min. Then 5.7 g of 35 wt.% hexamethylenetetramine solution was added, and stirred for 10 min to form a sol with a certain viscosity. The sol was dropped into hot oil at 110 ℃ through a needle, and the formed gel beads were aged in the hot oil for 16 h. After washing with petroleum ether, the gel beads were dried in an 80 ℃ oven for 24 h, and then calcined at 1000 ℃ for 4 h to obtain spherical alumina products. The physical property parameters of the products are shown in Table 1.

[0109] Table 1 Physical property parameters of the obtained spherical alumina

[0110]

[0111] The results in Table 1 show that the specific surface area of the spherical alumina prepared in the examples is more than 90 m 2 / g, the pore volume is more than 0.70 cm 3 / g, and the bulk density is 0.60 g / cm 3The left and right, and the intensity is greater than 55 N, significantly better than amorphous pseudo-boehmite directly prepared alumina (comparative example 1) and blocky alumina (comparative example 2), indicating that the carrier synthesized by rod-like pseudo-boehmite has better performance than other morphologies; at the same time, the content of alumina prepared by pseudo-boehmite synthesized by alcohol aluminum method is greater than 99%, significantly higher than that of alumina prepared by pseudo-boehmite synthesized by inorganic method (comparative example 3), indicating that the pseudo-boehmite synthesized by alcohol aluminum method has high purity. In addition, it can be seen from the comparison of examples 1-4 that the alumina prepared by using different structural additives has good performance, and the catalyst prepared by example 4 has the largest pore volume, crushing strength and obvious rod-like characteristics.

[0112] In summary, the carrier alumina synthesized by the method can meet the application requirements of propane dehydrogenation, catalytic reforming and the like.

[0113] The above only describes the preferred embodiments of the present application, and any changes and modifications made within the scope of the present application should be included in the scope of the present application.

Claims

1. A low-cost method for preparing macroporous spherical alumina, characterized in that, First, amorphous pseudoboehmite was prepared using the aluminum alkoxide method. Then, micron-sized rod-shaped alumina was prepared by simple mechanical grinding and solvent-free crystallization. Finally, millimeter-sized spherical alumina was obtained by hot oil column forming. Specifically, it includes the following steps: (1) Amorphous pseudoboehmite was prepared by using aluminum alkoxide as an aluminum source for hydrolysis reaction; (2) After adding structural aids and dispersants to the amorphous pseudoboehmite obtained in step (1), the mixture is then ultrasonically dispersed to obtain a precursor powder with uniform component distribution. (3) After mechanically grinding the precursor powder obtained in step (2), it is aged at room temperature to obtain micron-sized rod-shaped pseudoboehmite; (4) The micron-sized rod-shaped pseudo-boehmite obtained in step (3) is dissolved and dropped into a hot oil column to form gel microspheres. After aging, washing, drying and calcining, macroporous spherical alumina is obtained. The structural additives mentioned in step (2) include one or more of ammonium bicarbonate, hexadecyltrimethylammonium bromide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and N,N-dimethylformamide, and their dosage is calculated based on an N / Al molar ratio of 0.05 to 0.5 with that of amorphous pseudoboehmite.

2. The method for preparing low-cost macroporous spherical alumina according to claim 1, characterized in that, The organic aluminum alkoxides mentioned in step (1) include one or more of aluminum isopropoxide, aluminum sec-butoxide, aluminum n-butoxide, and aluminum n-pentoxide.

3. The method for preparing low-cost macroporous spherical alumina according to claim 1, characterized in that, The hydrolysis reaction in step (1) is carried out at a temperature of 20-80 °C for 2-8 h.

4. The method for preparing low-cost macroporous spherical alumina according to claim 1, characterized in that, The dispersant mentioned in step (2) includes one or more of stearic acid, oleic acid, polyvinyl alcohol, and polyacrylic acid, and its amount is 0.2 to 2% of the mass of amorphous boehmite.

5. The method for preparing low-cost macroporous spherical alumina according to claim 1, characterized in that, The mechanical grinding in step (3) uses a horizontal ball mill or a planetary ball mill.

6. The method for preparing low-cost macroporous spherical alumina according to claim 5, characterized in that, When using a horizontal ball mill, the grinding jar is made of polytetrafluoroethylene, the grinding beads are made of yttrium-stabilized zirconia ceramic with a diameter of 1~5mm, the material volume filling rate is 35%~65%, the ball mill speed is 15~75 r / min, and the ball milling time is 24~120 h.

7. The method for preparing low-cost macroporous spherical alumina according to claim 5, characterized in that, When using a planetary ball mill, the grinding jar is made of polytetrafluoroethylene, the grinding beads are made of yttrium oxide-stabilized zirconia ceramic with a diameter of 0.3~3mm, the material volume filling rate is 35%~65%, the ball mill speed is 100~250 r / min, and the ball milling time is 12~48 h.

8. The method for preparing low-cost macroporous spherical alumina according to claim 1, characterized in that, The aging time in step (3) is 24~48 h.

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