A method for preparing a high pore volume spherical alumina

Abstract

The application discloses a preparation method of high-pore-volume spherical alumina, which comprises the following steps: high-temperature treatment of pseudo-boehmite to fix pores, then soaking the pseudo-boehmite after pore fixing in hydrogen peroxide for hydroxyl enrichment treatment, and finally adopting a hot oil column forming method to prepare high-pore-volume spherical alumina. The method of the application uses a simple high-temperature treatment method to fix the pore structure of the pseudo-boehmite, prevents the collapse of the pseudo-boehmite in the peptization process, and uses hydrogen peroxide soaking to solve the problem of low peptization of the treated pseudo-boehmite, so as to prepare high-pore-volume spherical alumina. The method is convenient to operate, high in stability, low in cost and suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of inorganic material preparation, and relates to a preparation method of spherical alumina, in particular to a method for preparing spherical alumina with high pore volume by simply high-temperature pore solidification and hydrogen-rich pretreatment of precursor pseudo-boehmite. BACKGROUND

[0002] Due to the good thermal stability, strong adsorption capacity, high surface activity, adjustable specific surface area and controllable pore structure of alumina, the alumina is widely used as a catalyst carrier, an adsorbent and the like in different industrial fields. Industrial applications have certain requirements for the morphology of alumina, and the commonly used shapes include spherical, cylindrical, strip-shaped, trilobate and the like. Among them, the spherical alumina has a smooth surface, is easy to load and unload, facilitates the flow of reaction and adsorption gas, has a small bed pressure drop after packing, is good in wear resistance and is not easy to be pulverized, and is strong in adaptability, and can almost replace any other shape of catalyst or adsorbent, and is the most widely used shaped alumina in industrial applications at present.

[0003] The shaping method of spherical alumina includes spray drying, rotary balling and oil column shaping, and the oil column shaping is the most widely used shaping method at present due to its high product sphericity and strong controllability. The general process of hot oil column shaping method is as follows: the precursor aluminum source is reacted with acid to form an aluminum sol, then a gelling agent is added for mixing and stirring to obtain an aluminum sol mixture with appropriate viscosity and solid content, then the aluminum sol mixture is dropped into a hot oil column to form a ball, and the ball is further aged in an oil bath to improve the solidification degree, and finally the spherical alumina carrier is obtained after washing, drying and calcination. In the whole production process of spherical alumina, the properties of the precursor aluminum source largely determine the properties of the final product. At present, the most commonly used aluminum source is pseudo-boehmite. The properties of pseudo-boehmite obtained by different methods are quite different, and often cannot meet the specific industrial application requirements. Adjusting the properties of the aluminum source requires a large amount of research and development costs, and the product has a narrow application range and low economic benefits. Therefore, modifying the aluminum source in the shaping process to adjust the properties of the spherical alumina is a widely used method at present.

[0004] Chinese patent CN 104891539A introduces a modification method of spherical alumina particles, which modifies the spherical alumina by adding liquid paraffin, different surfactants and activated carbon, so as to improve the pore volume and compressive strength of the product, but the method has problems such as additive residue, reduction of product purity and poor stability.

[0005] CN 115872424A introduces a method for preparing spherical alumina by mixing active alumina powder and pseudo-boehmite powder as aluminum source. The method prepares spherical alumina with large pore volume by incorporating high-pore-volume active alumina into pseudo-boehmite sol, but is limited by the problems of mixing uniformity and narrow selection of aluminum source, and has insufficient process flexibility, low product strength, and poor wear resistance.

[0006] In most of the currently disclosed methods for preparing spherical alumina, additives are added or aluminum sources are mixed to expand the pores of the spherical alumina. However, the addition of additives increases the cost, and some additives are difficult to remove by calcination, which is not suitable for preparing active alumina with low-temperature calcination phase. The mixing of aluminum sources is limited by the differences in the properties of the aluminum sources, and has the disadvantages of poor mixing uniformity, complex ball forming process, and poor process stability. SUMMARY

[0007] The present application provides a method for preparing high-pore-volume spherical alumina, which uses inexpensive and readily available commercial aluminum sources, and only requires simple high-temperature treatment and hydrogen peroxide soaking of the aluminum sources to obtain high-pore-volume spherical alumina. The method is easy to operate, has high stability, low cost, and is suitable for large-scale production.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0009] A method for preparing high-pore-volume spherical alumina, which is prepared by high-temperature treatment of pseudo-boehmite to fix the pores, then soaking the fixed-pore pseudo-boehmite in hydrogen peroxide for hydroxyl-rich treatment, and then using a hot oil column forming method to prepare high-pore-volume spherical alumina. The specific steps include:

[0010] (1) After high-temperature treatment of pseudo-boehmite, it is soaked in a hydrogen peroxide solution for hydroxyl-rich treatment, and then dried to obtain pretreated pseudo-boehmite;

[0011] (2) Water and acid are added to the pretreated pseudo-boehmite, mixed to form a suspension, and then mechanically ground to obtain an aluminum sol;

[0012] (3) A gelling agent is added to the aluminum sol obtained in step (2), and the mixture is stirred and uniformly mixed, then the mixture is dropped into a hot oil column through a syringe pump to form gel beads, and then aged, washed, dried, and calcined to obtain the high-pore-volume spherical alumina.

[0013] Further, the high-temperature treatment in step (1) is carried out at a temperature of 150 ℃ to 300 ℃ for 1 h to 8 h.

[0014] Further, the concentration of the hydrogen peroxide solution used in step (1) is 5 wt.% to 30 wt.%.

[0015] Further, the soaking time in step (1) is 1 h-8 h.

[0016] Further, the acid in step (2) is one or more of nitric acid, hydrochloric acid, sulfuric acid, acetic acid, and citric acid.

[0017] Further, the mass ratio of the acid and water added in step (2) is 1:50-1:150.

[0018] Further, the solid content of the suspension obtained in step (2) is 10 wt.%-30 wt.%. + The molar ratio of / Al2O3 is 0.03-0.10.

[0019] Further, the gelling agent in step (3) is one or more of hexamethylenetetramine, ethylenediamine, urea, ammonium carbonate, ammonium bicarbonate, and tetramethylammonium hydroxide.

[0020] Further, the molar ratio of the gelling agent used in step (3) to Al2O3 in the aluminum sol is 0.01-0.1.

[0021] Further, the forming oil used in step (3) is one of vacuum pump oil, lubricating oil, edible oil, and turbine oil.

[0022] Further, the temperature of the hot oil column in step (3) is 60-140 ℃, and the oil column height is 1-2.5 m.

[0023] Further, the temperature of the aging in step (3) is 100-200 ℃, and the time is 2-24 h.

[0024] Further, the temperature of the drying in step (3) is 40-120 ℃, and the time is 6-24 h.

[0025] Further, the temperature of the calcination in step (3) is 500-1200 ℃, the time is 2-8 h, and the calcination atmosphere is air.

[0026] The significant advantages of the present application are:

[0027] (1) The present application uses a cheap and readily available commercial aluminum source as a raw material, fixes the pore structure of pseudo-boehmite through simple high-temperature treatment, prevents its collapse during peptization, and, in view of the problem that the pseudo-boehmite loses interlayer hydroxyl groups after high-temperature treatment, resulting in poor peptization performance and inability to form, the pseudo-boehmite after high-temperature treatment is soaked in hydrogen peroxide for hydroxyl-rich treatment to re-increase its peptization performance, thereby obtaining high-pore-volume spherical alumina.

[0028] (2) The method is convenient to operate, high in stability, low in cost and suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Scanning electron microscope images of samples obtained in Comparative Example 1 (a) and Examples 1 (b), 5 (c). DETAILED DESCRIPTION

[0030] A preparation method of high-pore-volume spherical alumina, comprising the following steps:

[0031] (1) After calcining pseudo-boehmite at a high temperature of 150-300 DEG C for 1-8 h, the pseudo-boehmite is soaked in a hydrogen peroxide solution with a concentration of 5-30 wt.% for 1-8 h, and then dried to obtain pretreated pseudo-boehmite;

[0032] (2) Acid and water are added to the pretreated pseudo-boehmite at a mass ratio of 1:50-1:150, and mixed to prepare a suspension with a solid content of 10-30 wt.% and a H + / Al2O3 molar ratio of 0.03-0.10, and then mechanically ground to obtain an alumina sol;

[0033] (3) A gelling agent is added to the alumina sol obtained in step (2) at a molar ratio of gelling agent / Al2O3 of 0.01-0.1, and the mixture is stirred and uniformly mixed, and then the mixture is dropped into a hot oil column (oil column height: 1-2.5 m) at 60-140 DEG C through a syringe pump to form gel beads, and then the gel beads are aged at 100-200 DEG C for 2-24 h, washed, dried at 40-120 DEG C for 6-24 h, and calcined at 500-1200 DEG C under an air atmosphere for 2-8 h to obtain high-pore-volume spherical alumina.

[0034] In step (2), the acid is one or more of nitric acid, hydrochloric acid, sulfuric acid, acetic acid and citric acid.

[0035] In step (3), the gelling agent is one or more of hexamethylenetetramine, ethylenediamine, urea, ammonium carbonate, ammonium bicarbonate and tetramethylammonium hydroxide.

[0036] 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.

[0037] The properties of the commercial pseudo-boehmite used are as follows:

[0038] Specific surface area: 210±20 m 2 / g;

[0039] Pore volume: 0.8±0.05 cm 3 / g;

[0040] Average pore size: 21 ± 1 nm

[0041] Peptization index: 84 ± 1 %.

[0042] Measurement method

[0043] Particle size: A CAMSIZER X2 dynamic image method particle size and shape analyzer was used to test 100 g of the sample poured into the test table.

[0044] Bulk density: A certain amount of sample was loaded into a 250 mL measuring cup, and the sample was tightly packed by knocking and vibrating. The sample that exceeded the measuring cup was removed, and the weight of the sample was measured to calculate the bulk density.

[0045] Specific surface area: An ASAP 2460 automatic adsorption instrument (produced by Micromeritics Company, USA) was used for testing. About 0.25 g of the sample was weighed, pretreated, and then measured to obtain the N2 adsorption-desorption curve. The specific surface area of the measured sample was calculated by the BET method, the pore volume of the sample was calculated by the single-point method, and the pore size of the sample was calculated by the BJH method.

[0046] Crystal phase: A D / max Ultima IV X-ray diffractometer (produced by Rigaku Company, Japan) was used for analysis. The synthesized sample was crushed and placed in an agate mortar to test the powder.

[0047] Crushing strength: A particle strength tester (model DL4, Dalian Penghui Technology Development Co., Ltd.) was used to test the crushing strength of the alumina pellets. A total of 100 samples were measured for each sample, and the average value was taken as the crushing strength of the alumina pellets.

[0048] Peptization index: About 0.5 g of the pseudo-boehmite sample to be tested was weighed and transferred to a muffle furnace. The temperature was raised from room temperature to 1000 °C at a rate of 5 °C / min, and the temperature was kept constant for 4 h. After the calcination was completed, the sample was naturally cooled to room temperature and weighed. m 1 g of the sample was weighed and transferred to a muffle furnace. The temperature was raised from room temperature to 1000 °C at a rate of 5 °C / min, and the temperature was kept constant for 4 h. After the calcination was completed, the sample was naturally cooled to room temperature and weighed m 2 g, then the mass fraction of alumina in the sample was ω m 2 / m 1× 100%, repeat the above step 5 times, take the average value; 20.0 g of pseudo-boehmite was weighed into a 200 ml beaker, (100 x ω - 20) g of deionized water was added to prepare a pseudo-boehmite suspension with a solid content (alumina content) of 20%, (20 x ω x 0.16) g of 65% mass fraction concentrated nitric acid was added, and a stirrer was used to stir for 30 min. The prepared alumina sol was transferred to a 200 ml centrifuge tube, and a centrifuge was used to centrifuge at 3000 r / min for 30 min. The supernatant was transferred to a 250 ml porcelain dish, which was placed in a 120 ℃ oven and dried for 24 h. Then it was transferred to a muffle furnace, and the temperature was raised from room temperature to 1000 ℃ at a rate of 5 ℃ / min, and kept at 1000 ℃ for 4 h. After natural cooling to room temperature, the sample was taken out and weighed m 3 g, and the peptization index of the sample was m 3 / 20ω) x 100%.

[0049] Comparative example:

[0050] (1) Preparation of alumina sol: 50 g of commercial pseudo-boehmite powder was placed in a beaker, 134.1 g of deionized water was added and stirred for 30 min to slurry, and then 6.0 g of 20wt.% nitric acid solution was added to prepare a suspension with a solid content of 20wt.% and a molar ratio of H + / A2O3 of 0.05. After stirring for 2 h to prepare the alumina sol, 3.7 g of 35wt.% hexamethylenetetramine was added dropwise, and the mixture was further gelled by stirring.

[0051] (2) Molding: a heated oil column with a height of 180 cm and a temperature of 100 ℃ was used, and a hot oil circulating pump was used for hot oil filling. After the hot oil filling was completed, the sol prepared in step (1) was dropped into the molding column using a syringe pump equipped with a 0.5 mm inner diameter needle; the dropping speed was 2.5 g / min (based on the mass of the raw material powder).

[0052] (3) Post-treatment: the molded gel particles were placed in the original container for aging, the aging temperature was 120 ℃, and the aging time was 12 h. After aging, the sample was transferred to a crucible, washed with petroleum ether for 2-3 times, and then dried in an oven at a temperature of 60 ℃ for 14 h. After drying, the sample was transferred to a muffle furnace for calcination, the calcination temperature was 600 ℃, the calcination time was 4 h, the calcination atmosphere was air, and after calcination, the sample was cooled to room temperature to obtain a spherical alumina product. The physical property parameters of the product are shown in Table 1.

[0053] Example 1:

[0054] (1) High temperature pretreatment: take a certain amount of commercial pseudo-boehmite, treat in a blast drying oven at 200 ℃ for 2 h.

[0055] (2) Preparation of alumina sol: put 50 g of the high-temperature pretreated pseudo-boehmite powder into a beaker, add 134.1 g of deionized water and stir for 30 min to slurry, then add 6.0 g of a nitric acid solution with a mass concentration of 20 wt.% to obtain a suspension with a solid content of 20 wt.% and a H + / A2O3 molar ratio of 0.05, stir for 2 h to prepare the alumina sol, then drop in 3.7 g of a hexamethylenetetramine solution with a mass concentration of 35 wt.% and continue to stir to further gelate the sol.

[0056] (3) Molding: adopt a sleeve heating hot oil column, the oil column height is 180 cm, the oil column temperature is 100 ℃, adopt a hot oil circulating pump to fill hot oil, after the hot oil filling is completed, use an injection pump provided with a 0.5 mm inner diameter needle to drop the sol prepared in step (2) into the molding column; the dropping speed is 2.5 g / min (calculated based on the mass of the raw material powder).

[0057] (4) Post-treatment: after the gel particles are molded, they are placed in the original container for aging, the aging temperature is 120 ℃, and the aging time is 12 h. After aging is completed, the sample is transferred to a crucible, washed with petroleum ether for 2-3 times, and then placed in an oven for drying, the drying temperature is 60 ℃, and the drying time is 14 h. After drying is completed, the sample is transferred to a muffle furnace for calcination, the calcination temperature is 600 ℃, the calcination time is 4 h, the calcination atmosphere is air, and after calcination is completed, the temperature is lowered to room temperature to obtain a spherical alumina product, and the physical property parameters of the product are listed in Table 1.

[0058] Example 2:

[0059] (1) High temperature pretreatment: take a certain amount of commercial pseudo-boehmite, treat in a blast drying oven at 200 ℃ for 2 h.

[0060] (2) Hydroxyl-rich treatment: put the high-temperature treated pseudo-boehmite into a 10 wt.% hydrogen peroxide solution and soak for 2 h, then place it in an oven for drying, the drying temperature is 100 ℃, and the drying time is 14 h, to obtain the pretreated pseudo-boehmite.

[0061] (3) Preparation of alumina sol: put 50 g of the high-temperature pretreated pseudo-boehmite powder into a beaker, add 134.1 g of deionized water and stir for 30 min to slurry, then add 6.0 g of a nitric acid solution with a mass concentration of 20 wt.% to obtain a suspension with a solid content of 20 wt.% and a H +After the alumina sol was prepared by stirring the suspension with A2O3molar ratio of 0.05 for 2 h, 3.7 g of hexamethylenetetramine with mass concentration of 35 wt.% was added dropwise, and the stirring was continued to make it further gel.

[0062] (4) Forming: a hot oil column was heated by a sleeve, the height of the oil column was 180 cm, the temperature of the oil column was 100 °C, a hot oil circulating pump was used for hot oil filling, and after the hot oil filling was completed, the sol prepared in step (3) was dropped into the forming column using a syringe pump equipped with a 0.5 mm inner diameter needle; the dropping speed was 2.5 g / min (based on the mass of the raw material powder).

[0063] (5) Post-treatment: the gel particles after forming were placed in the original container for aging, the aging temperature was 120 °C, and the aging time was 12 h. After aging was completed, it was transferred to a crucible, washed with petroleum ether for 2-3 times, and then placed in an oven for drying, the drying temperature was 60 °C, and the drying time was 14 h. After drying was completed, the sample was transferred to a muffle furnace for calcination, the calcination temperature was 600 °C, the calcination time was 4 h, the calcination atmosphere was air, and after calcination was completed, it was cooled to room temperature to obtain a spherical alumina product, and the physical property parameters are listed in Table 1.

[0064] Example 3:

[0065] (1) High-temperature pretreatment: a certain amount of commercial pseudo-boehmite was treated at 200 °C for 2 h in a forced air drying oven.

[0066] (2) Hydroxyl-rich treatment: the high-temperature treated pseudo-boehmite was soaked in a 20 wt.% hydrogen peroxide solution for 2 h, and then dried in an oven, the drying temperature was 100 °C, and the drying time was 14 h, to obtain the pretreated pseudo-boehmite.

[0067] (3) Preparation of alumina sol: 50 g of the pretreated pseudo-boehmite powder was placed in a beaker, 134.1 g of deionized water was added and stirred for 30 min for slurry, and then 6.0 g of nitric acid solution with mass concentration of 20 wt.% was added, and the mixture was mixed to obtain a solid content of 20 wt.%, H + After the alumina sol was prepared by stirring the suspension with A2O3molar ratio of 0.05 for 2 h, 3.7 g of hexamethylenetetramine with mass concentration of 35 wt.% was added dropwise, and the stirring was continued to make it further gel.

[0068] (4) Forming: a hot oil column was heated by a sleeve, the height of the oil column was 180 cm, the temperature of the oil column was 100 °C, a hot oil circulating pump was used for hot oil filling, and after the hot oil filling was completed, the sol prepared in step (3) was dropped into the forming column using a syringe pump equipped with a 0.5 mm inner diameter needle; the dropping speed was 2.5 g / min (based on the mass of the raw material powder).

[0069] (5) Post-treatment: The shaped gel particles were aged in the original container at an aging temperature of 120 °C for 12 h. After aging, the particles were transferred to a crucible, washed with petroleum ether for 2-3 times, and then dried in an oven at a drying temperature of 60 °C for 14 h. After drying, the sample was transferred to a muffle furnace for calcination at a calcination temperature of 600 °C for 4 h in an air atmosphere. After calcination, the sample was cooled to room temperature to obtain a spherical alumina product. The physical property parameters of the product are listed in Table 1.

[0070] Example 4:

[0071] (1) High-temperature pretreatment: A certain amount of commercial pseudo-boehmite was treated at 200 °C for 2 h in a forced air drying oven.

[0072] (2) Hydroxyl-rich treatment: The high-temperature treated pseudo-boehmite was soaked in a 30 wt.% hydrogen peroxide solution for 2 h, and then dried in an oven at a drying temperature of 100 °C for 14 h to obtain the pretreated pseudo-boehmite.

[0073] (3) Preparation of alumina sol: 50 g of the pretreated pseudo-boehmite powder was placed in a beaker, 134.1 g of deionized water was added, and the mixture was stirred for 30 min to form a slurry. Then, 6.0 g of a 20 wt.% nitric acid solution was added to the slurry to obtain a suspension with a solid content of 20 wt.% and a molar ratio of H + / A2O3 of 0.05. The suspension was stirred for 2 h to obtain an alumina sol. Then, 3.7 g of a 35 wt.% hexamethylenetetramine solution was added dropwise, and the mixture was further stirred to form a gel.

[0074] (4) Shaping: A heating oil column was used with a jacketed tube, the oil column height was 180 cm, and the oil column temperature was 100 °C. A hot oil circulating pump was used for hot oil filling. After the hot oil filling was completed, an injection pump with a 0.5 mm inner diameter needle was used to drop the sol prepared in step (3) into the shaping column. The dropping speed was 2.5 g / min (based on the mass of the raw material powder).

[0075] (5) Post-treatment: The shaped gel particles were aged in the original container at an aging temperature of 120 °C for 12 h. After aging, the particles were transferred to a crucible, washed with petroleum ether for 2-3 times, and then dried in an oven at a drying temperature of 60 °C for 14 h. After drying, the sample was transferred to a muffle furnace for calcination at a calcination temperature of 600 °C for 4 h in an air atmosphere. After calcination, the sample was cooled to room temperature to obtain a spherical alumina product. The physical property parameters of the product are listed in Table 1.

[0076] Example 5:

[0077] (1) High temperature pretreatment: A certain amount of commercial pseudo-boehmite was treated at 200 °C for 2 h in a blast drying oven.

[0078] (2) Hydroxyl-rich treatment: The high-temperature treated pseudo-boehmite was soaked in a 20 wt.% hydrogen peroxide solution for 4 h, and then dried in an oven at 100 °C for 14 h to obtain the pretreated pseudo-boehmite.

[0079] (3) Preparation of alumina sol: 50 g of the pretreated pseudo-boehmite powder was placed in a beaker, 134.1 g of deionized water was added and stirred for 30 min for slurry, and then 6.0 g of a 20 wt.% nitric acid solution was added to obtain a suspension with a solid content of 20 wt.% and a molar ratio of H + / A2O3 of 0.05. After stirring for 2 h to prepare the alumina sol, 3.7 g of a 35 wt.% hexamethylenetetramine solution was added, and the stirring was continued to further gel the sol.

[0080] (4) Forming: A hot oil column with a height of 180 cm and a temperature of 100 °C was used for hot oil filling with a hot oil circulating pump. After the hot oil filling was completed, the sol prepared in step (3) was dropped into the forming column using a syringe pump equipped with a 0.5 mm inner diameter needle; the dropping speed was 2.5 g / min (based on the mass of the raw material powder).

[0081] (5) Post-treatment: The formed gel particles were aged in the original container at a temperature of 120 °C for 12 h. After aging, the sample was transferred to a crucible, washed with petroleum ether for 2-3 times, and then dried in an oven at a temperature of 60 °C for 14 h. After drying, the sample was transferred to a muffle furnace and calcined at a temperature of 600 °C for 4 h in an air atmosphere. After calcination, the sample was cooled to room temperature to obtain a spherical alumina product. The physical property parameters of the product are listed in Table 1.

[0082] Example 6:

[0083] (1) High temperature pretreatment: A certain amount of commercial pseudo-boehmite was treated at 200 °C for 2 h in a blast drying oven.

[0084] (2) Hydroxyl-rich treatment: The high-temperature treated pseudo-boehmite was soaked in a 20 wt.% hydrogen peroxide solution for 8 h, and then dried in an oven at 100 °C for 14 h to obtain the pretreated pseudo-boehmite.

[0085] (3) Preparation of alumina sol: 50 g of the pretreated pseudoboehmite powder was placed in a beaker, 134.1 g of deionized water was added and stirred for 30 min for slurry, then 6.0 g of nitric acid solution with a mass concentration of 20 wt.% was added, and a suspension with a solid content of 20 wt.% and a H + After the alumina sol was prepared by stirring the suspension with a molar ratio of Al203 / A2O3 of 0.05 for 2 h, 3.7 g of hexamethylenetetramine with a mass concentration of 35 wt.% was added dropwise, and further gelling was performed by continuous stirring.

[0086] (4) Forming: a heated oil column was used with a sleeve heating, the height of the oil column was 180 cm, the temperature of the oil column was 100 ℃, a hot oil circulating pump was used for hot oil filling, and after the hot oil filling was completed, the sol prepared in step (3) was dropped into the forming column using a syringe pump with a 0.5 mm inner diameter needle; the dropping speed was 2.5 g / min (based on the mass of the raw material powder).

[0087] (5) Post-treatment: the formed gel particles were aged in the original container, the aging temperature was 120 ℃, and the aging time was 12 h. After aging, the sample was transferred to a crucible, washed with petroleum ether for 2-3 times, and then dried in an oven, the drying temperature was 60 ℃, and the drying time was 14 h. After drying, the sample was transferred to a muffle furnace for calcination, the calcination temperature was 600 ℃, the calcination time was 4 h, the calcination atmosphere was air, and after calcination, the temperature was lowered to room temperature to obtain a spherical alumina product, and the physical property parameters are listed in Table 1.

[0088] Example 7:

[0089] (1) High-temperature pretreatment: a certain amount of commercial pseudoboehmite was treated at 150 ℃ for 2 h in a blast drying oven.

[0090] (2) Hydroxyl-rich treatment: the high-temperature treated pseudoboehmite was soaked in a 20 wt.% hydrogen peroxide solution for 4 h, and then dried in an oven, the drying temperature was 100 ℃, and the drying time was 14 h, to obtain the pretreated pseudoboehmite.

[0091] (3) Preparation of alumina sol: 50 g of the pretreated pseudoboehmite powder was placed in a beaker, 134.1 g of deionized water was added and stirred for 30 min for slurry, then 6.0 g of nitric acid solution with a mass concentration of 20 wt.% was added, and a suspension with a solid content of 20 wt.% and a H + After the alumina sol was prepared by stirring the suspension with a molar ratio of Al203 / A2O3 of 0.05 for 2 h, 3.7 g of hexamethylenetetramine with a mass concentration of 35 wt.% was added dropwise, and further gelling was performed by continuous stirring.

[0092] (4) Forming: a hot oil column was heated by a sleeve, the height of the oil column was 180 cm, the temperature of the oil column was 100 °C, hot oil filling was performed by a hot oil circulating pump, after the hot oil filling was completed, the sol prepared in step (3) was dropped into the forming column by using a syringe pump equipped with a 0.5 mm inner diameter needle; the dropping speed was 2.5 g / min (based on the mass of the raw material powder).

[0093] (5) Post-treatment: the formed gel particles were placed in the original container for aging, the aging temperature was 120 °C, the aging time was 12 h. After aging was completed, the sample was transferred to a crucible, washed with petroleum ether for 2-3 times, and then placed in a drying oven for drying, the drying temperature was 60 °C, and the drying time was 14 h. After drying was completed, the sample was transferred to a muffle furnace for calcination, the calcination temperature was 600 °C, the calcination time was 4 h, the calcination atmosphere was air, and after calcination was completed, the temperature was lowered to room temperature to obtain a spherical alumina product, and the physical property parameters of which are listed in Table 1.

[0094] Example 8:

[0095] (1) High-temperature pretreatment: a certain amount of commercial pseudo-boehmite was treated at 300 °C for 2 h in a forced air drying oven.

[0096] (2) Hydroxyl-rich treatment: the high-temperature treated pseudo-boehmite was soaked in a 20 wt.% hydrogen peroxide solution for 4 h, and then dried in an oven, the drying temperature was 100 °C, and the drying time was 14 h, to obtain the pretreated pseudo-boehmite.

[0097] (3) Preparation of alumina sol: 50 g of the pretreated pseudo-boehmite powder was placed in a beaker, 134.1 g of deionized water was added and stirred for 30 min for slurry, then 6.0 g of a 20 wt.% nitric acid solution was added, a suspension with a solid content of 20 wt.% and a H + / A2O3 molar ratio of 0.05 was obtained, and after stirring for 2 h, 3.7 g of a 35 wt.% hexamethylenetetramine solution was added, and further stirring was performed to further gel the sol.

[0098] (4) Forming: a hot oil column was heated by a sleeve, the height of the oil column was 180 cm, the temperature of the oil column was 100 °C, hot oil filling was performed by a hot oil circulating pump, after the hot oil filling was completed, the sol prepared in step (3) was dropped into the forming column by using a syringe pump equipped with a 0.5 mm inner diameter needle; the dropping speed was 2.5 g / min (based on the mass of the raw material powder).

[0099] (5) Post-treatment: The shaped gel particles were placed in the original container for aging at 120 °C for 12 h. After aging, the particles were transferred to a crucible and rinsed 2-3 times with petroleum ether. Then, they were placed in an oven to dry at 60 °C for 14 h. After drying, the samples were transferred to a muffle furnace for calcination at 600 °C for 4 h in an air atmosphere. After calcination, the samples were cooled to room temperature to obtain spherical alumina products. The physical properties of the products are listed in Table 1.

[0100] Example 9:

[0101] (1) High temperature pretreatment: Take a certain amount of commercial pseudoboehmite and treat it in a forced-air drying oven at 200 ℃ for 4 h.

[0102] (2) Hydroxyl enrichment treatment: The pseudoboehmite after high temperature treatment was soaked in 20 wt.% hydrogen peroxide solution for 4 hours, and then placed in an oven to dry at 100 ℃ for 14 hours to obtain the pretreated pseudoboehmite.

[0103] (3) Preparation of alumina sol: 50 g of pretreated boehmite powder was placed in a beaker, 134.1 g of deionized water was added and stirred for 30 min to form a slurry, and then 6.0 g of 20 wt.% nitric acid solution was added and mixed to obtain a solid content of 20 wt.% H. + An alumina sol was prepared by stirring a suspension with an A2O3 molar ratio of 0.05 for 2 h. Then, 3.7 g of hexamethylenetetramine with a mass concentration of 35 wt.% was added dropwise, and stirring was continued to further gel the alumina.

[0104] (4) Molding: The hot oil column is heated by a sleeve. The height of the oil column is 180 cm and the temperature of the oil column is 100 ℃. The hot oil is filled by a hot oil circulation pump. After the hot oil is filled, the sol prepared in step (3) is dripped into the molding column by an injection pump equipped with a needle with an inner diameter of 0.5 mm. The dripping speed is 2.5 g / min (based on the mass of the raw material powder).

[0105] (5) Post-treatment: The shaped gel particles were placed in the original container for aging at 120 °C for 12 h. After aging, the particles were transferred to a crucible and rinsed 2-3 times with petroleum ether. Then, they were placed in an oven to dry at 60 °C for 14 h. After drying, the samples were transferred to a muffle furnace for calcination at 600 °C for 4 h in an air atmosphere. After calcination, the samples were cooled to room temperature to obtain spherical alumina products. The physical properties of the products are listed in Table 1.

[0106] Example 10:

[0107] (1) High temperature pretreatment: take a certain amount of commercial pseudo-boehmite, and treat it in a blast drying oven at 200 °C for 8 h.

[0108] (2) Hydroxyl-rich treatment: immerse the high-temperature treated pseudo-boehmite in a 20 wt.% hydrogen peroxide solution for 4 h, and then dry it in an oven at 100 °C for 14 h to obtain the pretreated pseudo-boehmite.

[0109] (3) Preparation of alumina sol: place 50 g of the pretreated pseudo-boehmite powder into a beaker, add 134.1 g of deionized water and stir for 30 min to slurry, then add 6.0 g of a 20 wt.% nitric acid solution, mix to obtain a suspension with a solid content of 20 wt.% and an A1203 / A2O3 molar ratio of 0.05, and stir for 2 h to prepare an alumina sol. Then, add 3.7 g of a 35 wt.% hexamethylenetetramine solution, and continue stirring to further gel the sol. + (4) Forming: use a heated oil column with a height of 180 cm and a temperature of 100 °C, and use a hot oil circulating pump to fill the oil. After the hot oil is filled, use an injection pump with a 0.5 mm inner diameter needle to drop the sol prepared in step (3) into the forming column at a speed of 2.5 g / min (based on the mass of the raw material powder).

[0110] (5) Post-treatment: place the formed gel particles in the original container for aging at a temperature of 120 °C for 12 h. After aging, transfer the particles to a crucible, rinse them with petroleum ether for 2-3 times, and then dry them in an oven at a temperature of 60 °C for 14 h. After drying, transfer the sample to a muffle furnace, calcine it at a temperature of 600 °C for 4 h in an air atmosphere, and then cool it to room temperature to obtain a spherical alumina product. The physical property parameters of the product are listed in Table 1.

[0111] Table 1 Properties of the spherical alumina product

[0112]

[0113] In Table 1, it can be seen from the comparison of the comparative example and Examples 1 and 2 that the pore volume of the spherical alumina support collapses during the ball forming process in the comparative example. However, the pore structure of the pseudo-boehmite can be fixed by high temperature pretreatment to prevent the collapse of the pores during the ball forming process. In addition, the pseudo-boehmite loses the interlayer hydroxyl groups after high temperature treatment, which leads to poor peptization performance and failure to form a ball. However, the peptization performance of the pseudo-boehmite can be improved by soaking it in hydrogen peroxide solution to make it hydroxyl-rich, thereby successfully preparing a spherical alumina with high pore volume and meeting the requirements of commercial applications in terms of various performance parameters.

[0114] Meanwhile, it can be seen from the comparison of Examples 2-6 that, with the increase of the concentration of the hydrogen peroxide solution, the peptization index of the pseudoboehmite, and the sphericity and crushing strength of the prepared spherical alumina are also increased; and the soaking time has no obvious effect on the peptization index of the pseudoboehmite and the properties of the prepared spherical alumina.

[0115] It can be seen from the comparison of Example 5 and Examples 7-10 that, the high processing temperature can significantly reduce the crushing strength of the prepared spherical alumina; and the time of the high-temperature pretreatment has no obvious effect on the peptization index of the pseudoboehmite and the properties of the prepared spherical alumina.

[0116] The above only describes the preferred embodiments of the present application, and any equivalent changes and modifications made within the scope of the present application should be included in the scope of the present application.

Claims

1. A method for preparing high-porosity spherical alumina, characterized in that, The pseudoboehmite is subjected to high-temperature treatment to fix the channels. Then, the pseudoboehmite with fixed pores is soaked in hydrogen peroxide for hydroxyl enrichment treatment. Finally, it is made into high-porosity spherical alumina by hot oil column forming method. The high-temperature treatment is performed at a temperature of 150 ℃ to 300 ℃ for a duration of 1 h to 8 h.

2. The method for preparing high-porosity spherical alumina according to claim 1, characterized in that, Includes the following steps: (1) After high-temperature treatment, the pseudoboehmite is soaked in hydrogen peroxide solution and then dried to obtain pretreated pseudoboehmite. (2) Water and acid were added to the pretreated boehmite, and after mixing to form a suspension, aluminum sol was obtained by mechanical grinding. (3) Add a gelling agent to the aluminum sol obtained in step (2), stir and mix well, and then drip the mixture into the hot oil column through an injection pump to form gel spheres. After aging, washing, drying and calcining, the high-porosity spherical alumina is obtained.

3. The method for preparing high-porosity spherical alumina according to claim 2, characterized in that, The concentration of hydrogen peroxide solution used in step (1) is 5 wt.%~30 wt.%, and the soaking time is 1 h~8 h.

4. The method for preparing high-porosity spherical alumina according to claim 2, characterized in that, The mass ratio of acid to water added in step (2) is 1:50 to 1:150; the acid is one or more of nitric acid, hydrochloric acid, sulfuric acid, acetic acid, and citric acid.

5. The method for preparing high-porosity spherical alumina according to claim 2, characterized in that, The solid content of the suspension obtained in step (2) is 10 wt.%~30 wt.%, H + The molar ratio of Al2O3 is 0.03~0.

10.

6. The method for preparing high-porosity spherical alumina according to claim 2, characterized in that, The molar ratio of the gelling agent used in step (3) to Al2O3 in the aluminum sol is 0.01~0.1; The gelling agent is one or more of hexamethylenetetramine, ethylenediamine, urea, ammonium carbonate, ammonium bicarbonate, and tetramethylammonium hydroxide.

7. The method for preparing high-porosity spherical alumina according to claim 2, characterized in that, The temperature of the hot oil column in step (3) is 60~140 ℃.

8. The method for preparing high-porosity spherical alumina according to claim 2, characterized in that, The aging temperature in step (3) is 100~200 ℃ and the time is 2~24 h.

9. The method for preparing high-porosity spherical alumina according to claim 2, characterized in that, The roasting temperature in step (3) is 500~1200 ℃ and the time is 2~8 h.

Images