Porous spherical aluminum oxide with high hydrothermal stability as well as preparation method and application of porous spherical aluminum oxide

Abstract

The invention relates to the technical field of catalyst carriers, and discloses porous high-hydrothermal-stability spherical aluminum oxide as well as a preparation method and application thereof. The preparation method comprises the following steps: (1) firstly, mixing an aluminum source, water and acid to obtain pseudo sol, and then adding cationic macromolecular polyelectrolyte, a hard template agent and a surfactant into the pseudo sol for mixing; (2) performing ultrasonic treatment and oil ammonia column forming treatment on the product obtained in the step (1) to obtain gamma-Al2O3 spherical gel beads; and (3) aging, washing, drying and calcining the gamma-Al2O3 spherical gel beads obtained in the step (2) to obtain the porous spherical alumina with high hydrothermal stability. The spherical aluminum oxide prepared by the method has a large specific surface area and a lamellar hierarchical pore structure, and is beneficial to loading of a catalyst in the aluminum oxide. And moreover, the hydrothermal stability is obviously improved, the stability of the catalyst in petroleum reforming is obviously improved, and the catalyst has industrial production utilization value and commercial value.

Description

Technical Field

[0001] This invention relates to the field of catalyst support technology, specifically to a porous, highly hydrothermal stable spherical alumina, its preparation method, and its applications. Background Technology

[0002] Catalysts play a crucial role in the chemical industry, with approximately 70% of catalysts being supported catalysts. In these catalytic systems, the support not only provides a platform for the dispersion and fixation of active components but also exerts a decisive influence on the catalyst's activity, selectivity, and stability by controlling factors such as metal dispersion, acid-base properties, and pore structure. Among various supports, spherical γ-Al₂O₃ is widely used due to its high specific surface area, excellent pore structure, and high mechanical strength.

[0003] The main forming methods for spherical alumina include rotational forming, spray drying forming, oil-ammonia column forming, hot oil column forming, and water column forming. However, preparing spherical alumina with high purity, narrow particle size distribution, high hydrothermal stability, high mechanical strength, and suitability for industrial production remains a challenge.

[0004] CN120054447A reports a spherical alumina support, its preparation method, and its application. The method involves mixing aluminum hydroxide sol and acidic silica sol, then dropwise into a four-layer oil-ammonia-oil-water mixture column to form the alumina spheres. This effectively improves the sphericity, but the specific surface area of ​​the resulting alumina spheres is generally less than 200 m². 2 / g.

[0005] CN120039917A reports a method for preparing spherical alumina using an oil column molding process. A mixed alumina sol is prepared using aluminum powder, hydrochloric acid, aluminum compounds, and a dispersant. An amine-based coagulant is added during the preparation process, and then the finished alumina microspheres are obtained through oil column molding. This method effectively solves the problem of uneven particle size distribution caused by large differences in droplet volume, but it lacks research on the internal pore structure of the alumina spheres.

[0006] Current patent research largely focuses on controlling the outer surface of the alumina, with limited exploration of its internal structure. This, to some extent, restricts the improvement of alumina carrier performance. Therefore, to further increase the specific surface area and enrich the pore structure of spherical alumina, it is urgent to develop preparation strategies that can fully utilize its internal spatial structure, which has significant research and application value. Summary of the Invention

[0007] The purpose of this invention is to overcome the problems existing in the prior art and provide a porous, highly hydrothermal stable spherical alumina, its preparation method, and its applications. The spherical alumina prepared by this method has a rich porous structure inside, thereby improving its specific surface area and hydrothermal stability.

[0008] To achieve the above objectives, the first aspect of the present invention provides a method for preparing porous, highly hydrothermal stable spherical alumina, wherein the method includes the following steps: (1) First, aluminum source, water and acid are mixed to obtain pseudo sol, and then cationic polymeric polyelectrolyte, hard template agent and surfactant are added to the pseudo sol and mixed. (2) The product obtained in step (1) was subjected to ultrasonic treatment and oil-ammonia column molding treatment to obtain γ-Al2O3 spherical gel beads; (3) The γ-Al2O3 spherical gel beads obtained in step (2) are aged, washed, dried and calcined to obtain the porous high hydrothermal stability spherical alumina.

[0009] The second aspect of the present invention provides a porous, highly hydrothermal stable spherical alumina obtained by the preparation method described in the first aspect.

[0010] The third aspect of the present invention provides an application of porous, highly hydrothermal stable spherical alumina as a catalyst support according to the second aspect in petroleum reforming, heterogeneous catalysis and adsorption separation.

[0011] The beneficial technical effects achieved by the present invention through the above technical solution are as follows: (1) This invention introduces cationic polymeric polyelectrolytes, along with hard template agents and surfactants, into a pseudo-sol. By controlling the relevant dosages and subjecting the pseudo-sol to ultrasonic treatment, the cationic polymeric polyelectrolytes adsorb the pseudo-sol, promoting the uniform dispersion of the hard template agent in the sol to obtain a composite aluminum sol. This sol is then cured by oil-ammonia column molding to prepare spherical alumina with a multi-level pore distribution, significantly increasing the specific surface area. Furthermore, the specific surface area retention rate can reach up to approximately 78% after hydrothermal treatment.

[0012] (2) The spherical alumina prepared by this invention has a large specific surface area and a layered hierarchical porous structure, which is beneficial for the loading of catalysts inside the alumina. Furthermore, its hydrothermal stability is significantly improved, which helps to significantly enhance the stability of the catalyst in petroleum reforming, and has industrial production utilization value and commercial value.

[0013] (3) The preparation method described in this invention is simple to operate, low in cost, stable in production process, and easy to mass-produce. Attached Figure Description

[0014] Figure 1 An optical photograph of the porous, highly hydrothermal stable spherical alumina prepared in Example 1 of this invention.

[0015] Figure 2 The XRD pattern is shown in Example 1 of this invention.

[0016] Figure 3 This is a SEM image of the porous, highly hydrothermal stable spherical alumina prepared in Example 1 of the present invention.

[0017] Figure 4 The image shows the XRD pattern of the alumina prepared in Comparative Example 1.

[0018] Figure 5 SEM image of the alumina prepared for Comparative Example 1.

[0019] Figure 6 SEM image of the alumina prepared for Comparative Example 2.

[0020] Figure 7 The XRD pattern of the alumina prepared in Comparative Example 2 is shown. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] The first aspect of this invention provides a method for preparing porous, highly hydrothermal stable spherical alumina, wherein the method includes the following steps: (1) First, aluminum source, water and acid are mixed to obtain pseudo sol, and then cationic polymeric polyelectrolyte, hard template agent and surfactant are added to the pseudo sol; (2) The product obtained in step (1) was subjected to ultrasonic treatment and oil-ammonia column molding treatment to obtain γ-Al2O3 spherical gel beads, which were then mixed. (3) The γ-Al2O3 spherical gel beads obtained in step (2) are aged, washed, dried and calcined to obtain the porous high hydrothermal stability spherical alumina.

[0023] This invention is the first to synthesize spherical alumina using a cationic polymeric polyelectrolyte as the main pore-forming agent coupled with a hard template agent. The cationic polymeric polyelectrolyte can adsorb pseudosols, guiding them to aggregate around the alumina, which then leaves a rich porous structure after calcination. Simultaneously, the coupled hard template agent improves the mechanical strength of the spherical alumina and stabilizes the pores left by the pore-forming agent, making them less prone to collapse.

[0024] This invention uses ultrasonic treatment to accelerate the adsorption of pseudosol by cationic polymeric polyelectrolytes, while the hard template agent vibrates at high frequency to reduce agglomeration and fully disperse the material. After molding and curing, the alumina is filled with rich lamellar multi-level pores and has a higher specific surface area.

[0025] In some embodiments of the present invention, the aluminum source is selected from at least one of boehmite, boehmite and gibbsite.

[0026] In some embodiments of the present invention, the acid is selected from at least one of concentrated nitric acid, acetic acid, and hydrochloric acid.

[0027] In some embodiments of the present invention, the molar ratio of hydrogen ions in the acid to aluminum ions in the aluminum source is 0.03-0.1:1, for example 0.03:1, 0.0425:1, 0.056:1, 0.074:1, 0.1:1, and any value within the range of any two of the above values, preferably 0.0425-0.074:1.

[0028] In some embodiments of the present invention, the cationic polymeric polyelectrolyte is selected from at least one of quaternary ammonium salt type, primary amine salt type, secondary amine salt type and amphoteric type, and preferably from at least one of polydiallyldimethylammonium chloride (PDDA), polyetherimide (PEI), polyquaternary ammonium salt and polyglucosamine.

[0029] In some embodiments of the present invention, the amount of the cationic polymeric polyelectrolyte is 0.1-40% of the mass of the pseudosol, for example, 0.1%, 1.5%, 1.6%, 2%, 3%, 4%, 10%, 20%, 30%, 40%, and any value within the range of any two of the above values, preferably 1.5-4%. In the present invention, if the amount is too small, it will not play a role in the internal structure of alumina, the channels cannot be fully formed, and the pore structure will not be obvious; if the amount is too large, the internal pore structure of alumina will collapse, the mechanical strength will be low, and it will even be difficult to form spheres.

[0030] In some embodiments of the present invention, the hard template agent is a carbon-based solid organic and / or inorganic material, preferably at least one of polystyrene spheres, carbon spheres and starch.

[0031] In some embodiments of the present invention, the amount of the hard template agent is 0.1-45% of the mass of the pseudosol, for example 0.1%, 3%, 4%, 6%, 8%, 10%, 20%, 30%, 40%, 45%, and any value within the range of any two of the above values, preferably 3-8%. Within the specific scope of the present invention, a stable, continuous, and reproducible pore structure is formed.

[0032] In some embodiments of the present invention, the surfactant is selected from at least one of anionic surfactants, cationic surfactants and nonionic surfactants, preferably hexadecyltrimethylammonium bromide (CTAB) and / or sodium dodecyl sulfate (SDS).

[0033] In some embodiments of the present invention, the amount of surfactant used is 0.005-3% of the mass of the pseudosol, for example 0.005%, 0.0075%, 0.01%, 0.1%, 1%, 2%, 3%, and any value within the range of any two of the above values, preferably 0.0075-0.1%.

[0034] In some embodiments of the present invention, the conditions for the ultrasonic treatment in step (2) include: the voltage of the ultrasonic device is set to 12-24V; the ultrasonic time is 0.5-10min. For example, a 12V ultrasonic device is used to ultrasonically disperse the product obtained in step (1) for 2min.

[0035] In some embodiments of the present invention, the calcination conditions in step (3) include: a calcination temperature of 550-650°C, preferably 600°C; and a calcination time of 2-4 hours, preferably 3 hours. For example, calcination at 600°C for 3 hours.

[0036] In addition, the aging process can be carried out by aging in ammonia water for 12 hours; the washing process can be carried out by washing with deionized water 2-3 times to remove excess ammonia water; and the drying process can be carried out by drying at 80℃ for 10 hours.

[0037] The second aspect of the present invention provides a porous, highly hydrothermal stable spherical alumina obtained by the preparation method described in the first aspect.

[0038] In some embodiments of the present invention, the spherical alumina has a lamellar hierarchical porous structure inside.

[0039] In some embodiments of the present invention, the specific surface area of ​​the spherical alumina is 200-500 m². 2 / g, preferably 205-230m 2 / g.

[0040] In some embodiments of the present invention, the pore volume of the spherical alumina is 0.45-0.76 mL / g, preferably 0.48-0.58 mL / g.

[0041] In some embodiments of the present invention, the spherical alumina maintains a specific surface area of ​​160-350 m² after hydrothermal treatment at 600°C. 2 / g, preferably 161-174m 2 / g.

[0042] In some embodiments of the present invention, the spherical alumina retains a specific surface area of ​​73.9-78.5% after hydrothermal treatment at 600°C.

[0043] The third aspect of the present invention provides an application of porous, highly hydrothermal stable spherical alumina as a catalyst support according to the second aspect in petroleum reforming, heterogeneous catalysis and adsorption separation.

[0044] The present invention will be described in detail below through embodiments.

[0045] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0046] Source of materials: Boehmite: pore volume 0.41 mL / g, pore size 5.3 nm; Bismuth trihydrate: purchased from Maclean's; Concentrated nitric acid: mass concentration of 68%; PDDA: Purchased from Aladdin, product number P109721-100mL; PEI: Purchased from Aladdin, item number P434393-100mL; Polyquaternium salt: purchased from Aladdin, product number L475431-250mL; Polyglucosamine: purchased from Aladdin, item number C105802-25g; Carbon balls: purchased from Aladdin, product number C196582-100mg; Starch: Purchased from Jieshikai, item number KA741255-500g; Polystyrene spheres are prepared by the following method: First, 70 mL of styrene was thoroughly washed sequentially with 20 mL of 10 wt% sodium hydroxide solution and deionized water to remove the stabilizer. Then, 68 mL of the washed styrene was added to a three-necked round-bottom flask containing 500 mL of water containing 1.6 g of PVP. After bubbling with nitrogen for 15 min, the mixture was stirred at 75 °C for 30 min under magnetic stirring. Next, 50 mL of an aqueous solution containing 1 g of K₂S₂O₈ was rapidly added to initiate the polymerization reaction of styrene. After stirring continuously at this temperature for 24 h, the mixture was cooled, and the resulting emulsion product was monodisperse colloidal polystyrene spheres. These were filtered and dried to obtain the polystyrene spheres. The PVP was purchased from Aladdin, catalog number P434441-5g.

[0047] Example 1 This embodiment illustrates the preparation of porous, highly hydrothermal stable spherical alumina.

[0048] (1) Mix 10g of boehmite with water to prepare a suspension with a solid content of 15%, and then add 450μL of concentrated nitric acid to obtain a pseudo sol; then add 1g of PDDA and 2g of polystyrene balls to the pseudo sol and stir continuously, then add 5mg of CTAB as a surfactant and stir for 4h; The molar ratio of hydrogen ions in concentrated nitric acid to aluminum ions in pseudoboehmite was 0.0425:1; the amount of PDDA used was 1.5% of the pseudosol mass; the amount of polystyrene spheres used was 3% of the pseudosol mass; and the amount of CTAB used was 0.0075% of the pseudosol mass. (2) Use a 12V ultrasonic device to ultrasonically disperse the product obtained in step (1) for 0.5 min; then drop it into an oil-ammonia column (the oil phase is petroleum ether, 6 cm high; the ammonia phase is 8 wt% ammonia, 1 m high) for molding treatment to obtain γ-Al2O3 spherical gel beads. (3) The γ-Al2O3 spherical gel beads were aged in ammonia water for 12 hours, then washed 2-3 times with deionized water to remove excess ammonia water; the washed product was dried at 80°C for 10 hours, and then calcined at 600°C for 3 hours to obtain the porous, highly hydrothermal stable spherical alumina with the chemical formula γ-Al2O3 and the morphology of spherical particles, such as... Figure 1 As shown.

[0049] Figure 2 The corresponding XRD patterns show obvious diffraction peaks at 2θ of 19.65°, 32.72°, 37.05°, 39.47°, 46.30°, 61.60° and 67.05°, which correspond to the (111), (220), (311), (222), (400), (511) and (440) crystal planes of γ-Al2O3, respectively.

[0050] Figure 3 The corresponding SEM images show macroporous structures inside the alumina microspheres, along with a layered hierarchical porous structure. This structural change is caused by the introduction of PDDA, resulting in a macroporous-mesoporous structure within the microspheres.

[0051] Example 2 This embodiment illustrates the preparation of porous, highly hydrothermal stable spherical alumina.

[0052] (1) Mix 10g of pseudoboehmite with water to prepare a suspension with a solid content of 20%, and then add 450μL of concentrated nitric acid to obtain a pseudo sol; then add 0.8g of PEI and 4g of carbon balls to the pseudo sol and stir continuously, then add 5mg of CTAB as a surfactant and stir for 4h; The molar ratio of hydrogen ions in concentrated nitric acid to aluminum ions in pseudoboehmite was 0.0425:1; the amount of PEI was 1.6% of the pseudosol mass; the amount of carbon spheres was 8% of the pseudosol mass; and the amount of CTAB was 0.01% of the pseudosol mass. (2) Use a 12V ultrasonic device to ultrasonically disperse the product obtained in step (1) for 4 min; then drop it into an oil-ammonia column (the oil phase is petroleum ether, 6 cm high; the ammonia phase is 8 wt% ammonia, 1 m high) for molding treatment to obtain γ-Al2O3 spherical gel beads. (3) The γ-Al2O3 spherical gel beads were aged in ammonia water for 12 hours, and then washed with deionized water 2-3 times to remove excess ammonia water. The washed product was dried at 80°C for 10 hours and then calcined at 600°C for 3 hours to obtain the porous high hydrothermal stability spherical alumina with the chemical formula γ-Al2O3 and the morphology of spherical particles.

[0053] Example 3 This embodiment illustrates the preparation of porous, highly hydrothermal stable spherical alumina.

[0054] (1) Mix 5g of boehmite and 5g of gibbsite with water to prepare a suspension with a solid content of 20%, and then add 450μL of concentrated nitric acid to obtain a pseudo sol; then add 2g of polyquaternium salt and 2g of starch to the pseudo sol and stir continuously, then add 5mg of CTAB as a surfactant and stir for 4h; The molar ratio of hydrogen ions in concentrated nitric acid to aluminum ions in pseudoboehmite and gibbsite was 0.056:1; the amount of polyquaternium salt was 4% of the pseudosol mass; the amount of starch was 4% of the pseudosol mass; and the amount of CTAB was 0.01% of the pseudosol mass. (2) Use a 12V ultrasonic device to ultrasonically disperse the product obtained in step (1) for 5 min; then drop it into an oil-ammonia column (the oil phase is petroleum ether, 6 cm high; the ammonia phase is 8 wt% ammonia, 1 m high) for molding treatment to obtain γ-Al2O3 spherical gel beads. (3) The γ-Al2O3 spherical gel beads were aged in ammonia water for 12 hours, and then washed with deionized water 2-3 times to remove excess ammonia water. The washed product was dried at 80°C for 10 hours and then calcined at 600°C for 3 hours to obtain the porous high hydrothermal stability spherical alumina with the chemical formula γ-Al2O3 and the morphology of spherical particles.

[0055] Example 4 This embodiment illustrates the preparation of porous, highly hydrothermal stable spherical alumina.

[0056] (1) Mix 10g of boehmite with water to prepare a suspension with a solid content of 20%, and then add 450μL of concentrated nitric acid to obtain a pseudo sol; then add 1.5g of PDDA and 3g of polystyrene balls to the pseudo sol and stir continuously, then add 50mg of SDS as a surfactant and stir for 4h; The molar ratio of hydrogen ions in concentrated nitric acid to aluminum ions in pseudoboehmite was 0.0425:1; the amount of PDDA used was 3% of the pseudosol mass; the amount of polystyrene used was 6% of the pseudosol mass; and the amount of SDS used was 0.1% of the pseudosol mass. (2) Use a 12V ultrasonic device to ultrasonically disperse the product obtained in step (1) for 2 min; then drop it into an oil-ammonia column (the oil phase is petroleum ether, 6 cm high; the ammonia phase is 8 wt% ammonia, 1 m high) for molding treatment to obtain γ-Al2O3 spherical gel beads. (3) The γ-Al2O3 spherical gel beads were aged in ammonia water for 12 hours, and then washed with deionized water 2-3 times to remove excess ammonia water. The washed product was dried at 80°C for 10 hours and then calcined at 600°C for 3 hours to obtain the porous high hydrothermal stability spherical alumina with the chemical formula γ-Al2O3 and the morphology of spherical particles.

[0057] Example 5 This embodiment illustrates the preparation of porous, highly hydrothermal stable spherical alumina.

[0058] (1) Mix 10g of boehmite with water to prepare a suspension with a solid content of 20%, and then add 780μL of concentrated nitric acid to obtain a pseudo sol; then add 1g of polyglucosamine and 2g of carbon balls to the pseudo sol and stir continuously, then add 5mg of SDS as a surfactant and stir for 4h. The molar ratio of hydrogen ions in concentrated nitric acid to aluminum ions in pseudoboehmite was 0.074:1; the amount of polyglucosamine was 2% of the pseudosol mass; the amount of carbon spheres was 4% of the pseudosol mass; and the amount of SDS was 0.01% of the pseudosol mass. (2) Use a 12V ultrasonic device to ultrasonically disperse the product obtained in step (1) for 2 min; then drop it into an oil-ammonia column (the oil phase is petroleum ether, 6 cm high; the ammonia phase is 8 wt% ammonia, 1 m high) for molding treatment to obtain γ-Al2O3 spherical gel beads. (3) The γ-Al2O3 spherical gel beads were aged in ammonia water for 12 hours, and then washed with deionized water 2-3 times to remove excess ammonia water. The washed product was dried at 80°C for 10 hours and then calcined at 600°C for 3 hours to obtain the porous high hydrothermal stability spherical alumina with the chemical formula γ-Al2O3 and the morphology of spherical particles.

[0059] Comparative Example 1 Spherical alumina was prepared according to the method of Example 1, except that PDDA was not added in step (1).

[0060] Figure 4 The test results show that the prepared spherical alumina has obvious alumina diffraction peaks. Figure 5 The test results show that it has a large porous structure inside, with no obvious lamellar multi-level pores, only folds formed by pseudoboehmite.

[0061] Comparative Example 2 Spherical alumina was prepared according to the method of Example 1, except that polystyrene spheres were not added in step (1).

[0062] Figure 6 The test results showed that no obvious large pores were observed inside. The prepared spherical alumina exhibited obvious alumina diffraction peaks, such as... Figure 7 As shown.

[0063] Comparative Example 3 Spherical alumina was prepared according to the method of Example 1, except that PDDA and polystyrene spheres in step (1) were replaced with 3g of dodecane.

[0064] Comparative Example 4 Spherical alumina was prepared according to the method of Example 1, except that PDDA in step (1) was replaced with an equal amount of PEI.

[0065] Test case The average diameter, bulk density, pore volume, specific surface area, and crushing strength of the spherical alumina obtained in Examples 1-5 and Comparative Examples 1-4 were determined.

[0066] Measurement method: Average diameter: The diameter of the spherical alumina was measured multiple times using vernier calipers, and the average value was taken.

[0067] Bulk density: Weigh an appropriate amount of solid, pour it into a graduated cylinder, record the height of the particles, and the mass removed is the bulk density.

[0068] Pore ​​volume and specific surface area: tested using an N2 adsorption-desorption instrument.

[0069] Crushing strength: tested using a KHKQ-100 automatic particle strength tester.

[0070] In addition, the spherical alumina obtained in Examples 1-5 and Comparative Examples 1-4 were placed in a hydrothermal reaction apparatus and hydrothermally treated with 10% steam at 600°C for 120 hours. The specific surface area was then measured to calculate the specific surface area retention rate before and after treatment.

[0071] The results are shown in Table 1.

[0072] Table 1

[0073] As shown in Table 1, the spherical alumina prepared in the embodiments of the present invention is not significantly different from the comparative example in terms of average diameter, bulk density, and pore volume. After hydrothermal treatment, the alumina microspheres prepared in the present invention exhibit better specific surface area retention rates than the comparative example, reaching an advanced level with a specific surface area retention rate of 73.9-78.5%, demonstrating excellent hydrothermal stability. Furthermore, the spherical alumina prepared in the embodiments of the present invention has a crushing strength greater than 40 N, indicating that the lack of a hard template agent affects the mechanical strength of the spherical alumina.

[0074] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing porous, highly hydrothermal stable spherical alumina, characterized in that, The method includes the following steps: (1) First, aluminum source, water and acid are mixed to obtain pseudo sol, and then cationic polymeric polyelectrolyte, hard template agent and surfactant are added to the pseudo sol and mixed. (2) The product obtained in step (1) was subjected to ultrasonic treatment and oil-ammonia column molding treatment to obtain γ-Al2O3 spherical gel beads; (3) The γ-Al2O3 spherical gel beads obtained in step (2) are aged, washed, dried and calcined to obtain the porous high hydrothermal stability spherical alumina.

2. The preparation method according to claim 1, wherein, The aluminum source is selected from at least one of boehmite, boehmite and gibbsite. Preferably, the acid is selected from at least one of concentrated nitric acid, acetic acid, and hydrochloric acid; Preferably, the molar ratio of hydrogen ions in the acid to aluminum ions in the aluminum source is 0.03-0.1:1, more preferably 0.0425-0.074:

1.

3. The preparation method according to claim 1 or 2, wherein, The cationic polymeric polyelectrolyte is selected from at least one of quaternary ammonium salt, primary amine salt, secondary amine salt and amphoteric types, and preferably from at least one of polydiallyldimethylammonium chloride, polyetherimide, polyquaternary ammonium salt and polyglucosamine; Preferably, the amount of the cationic polymeric polyelectrolyte is 0.1-40% of the mass of the pseudosol, and more preferably 1.5-4%.

4. The preparation method according to any one of claims 1-3, wherein, The hard template agent is a carbon-based solid organic and / or inorganic material, preferably at least one of polystyrene spheres, carbon spheres and starch; Preferably, the amount of the hard template agent is 0.1-45% of the mass of the pseudosol, and more preferably 3-8%.

5. The preparation method according to any one of claims 1-4, wherein, The surfactant is selected from at least one of anionic surfactants, cationic surfactants and nonionic surfactants, preferably hexadecyltrimethylammonium bromide and / or sodium dodecyl sulfate; Preferably, the amount of surfactant used is 0.005-3% of the mass of the pseudosol, and more preferably 0.0075-0.1%.

6. The preparation method according to any one of claims 1-5, wherein, The conditions for ultrasonic treatment in step (2) include: the voltage of the ultrasonic device is set to 12-24V; the ultrasonic time is 0.5-10min.

7. The preparation method according to any one of claims 1-6, wherein, The calcination conditions in step (3) include: a calcination temperature of 550-650℃, preferably 600℃; and a calcination time of 2-4h, preferably 3h.

8. A porous, highly hydrothermal stable spherical alumina obtained by the preparation method according to any one of claims 1-7.

9. The spherical alumina according to claim 8, wherein, The spherical alumina has a layered, multi-level porous structure inside; Preferably, the specific surface area of ​​the spherical alumina is 200-500 m² / g. 2 / g, preferably 205-230m 2 / g; Preferably, the pore volume of the spherical alumina is 0.45-0.76 mL / g, more preferably 0.48-0.58 mL / g; Preferably, the spherical alumina maintains a specific surface area of ​​160-350 m² after hydrothermal treatment at 600℃. 2 / g, preferably 161-174m 2 / g; Preferably, the spherical alumina retains a specific surface area of ​​73.9-78.5% after hydrothermal treatment at 600℃.

10. The application of porous, highly hydrothermal stable spherical alumina as a catalyst support according to claim 8 or 9 in petroleum reforming, heterogeneous catalysis and adsorption separation.

Images