Aluminum oxide and preparation method thereof

Abstract

The present invention discloses an aluminum oxide and a preparation method thereof. The aluminum oxide is phosphorus-containing aluminum oxide and has the following properties: a pore volume of 0.7 to 1.2 mL / g, a phosphorus content of 0.3 wt% to 5.0 wt%, and a unit surface acidity of 0.001 to 0.002 mmol / m 2 The preparation method comprises adding bottom water to a reactor, then adding a sodium aluminate solution, a phosphate surfactant solution, and a cation exchange resin suspension for reaction. The resulting slurry is aged, then added with a cation exchange resin and separated. The separated slurry is filtered, dried, and calcined to obtain an alumina product. This preparation method eliminates the washing step in existing methods, significantly reducing wastewater discharge and optimizing the entire preparation process. Furthermore, the resulting alumina product has a high specific surface acid content, a large pore volume, and excellent hydraulic hardness.

Description

Technical Field

[0001] The present invention relates to the field of petrochemical industry, and relates to a catalytic material and a preparation method thereof, and in particular to an aluminum oxide suitable for being used as a catalyst carrier and a preparation method thereof. Background Art

[0002] Alumina, a porous, highly dispersed solid material, boasts excellent mechanical strength, high thermal and chemical stability, a suitable isoelectric point, and adjustable surface acidity and alkalinity, making it the most widely used catalyst support in the chemical and petroleum industries. Alumina supports are typically produced by dehydrating pseudoboehmite at high temperatures. Pseudoboehmite, also known as monohydrated alumina or pseudoboehmite, possesses incomplete crystalline water molecules and a spatial network structure, appearing as a white colloid (wet product) or powder (dry product). It exhibits high crystalline purity, excellent peptization properties, strong adhesion, a high specific surface area, and a large pore volume. Activated alumina, particularly γ-Al2O3, possesses excellent specific surface area and pore structure. Due to its large specific surface area, adjustable pore structure, and excellent thermal stability, it is widely used as a catalyst support, desiccant, and adsorbent in the petrochemical and fertilizer industries.

[0003] Industrial production methods for pseudo-boehmite mainly include organic alcohol aluminum method and inorganic neutralization method, depending on the raw materials. Among them, the inorganic neutralization method generally has three preparation methods in industry: aluminum chloride method, aluminum sulfate method and carbonization method. (1) Neutralization reaction of aluminum salt and alkali, such as aluminum chloride method: AlCl3+3NH4OH→Al(OH)3+3NH4Cl; (2) Double decomposition reaction of aluminum salt and aluminate, such as aluminum sulfate method: Al2(SO4)3+6NaAlO2+12H2O→8Al(OH)3+3Na2SO4. (3) Neutralization reaction of aluminate and acid, such as carbonization method: 2NaAlO2+CO2+3H2O→2Al(OH)3+Na2CO3. All three methods use neutralization method to generate aluminum hydroxide, and then remove impurity sodium in the water washing process. The washing water consumption is large, and a large amount of wastewater is generated. How to reduce the amount of washing water while ensuring the properties of alumina is the key point of concern for manufacturers.

[0004] CN201610674763.3 discloses a low-impurity pseudo-boehmite, a preparation method, and a preparation apparatus. The low-impurity pseudo-boehmite contains metal ion impurities ≤0.1% by weight. The method comprises preparing a raw pseudo-boehmite into a slurry; acidifying the slurry to obtain an acidified raw pseudo-boehmite; aging the raw pseudo-boehmite at a set temperature for a set time to obtain an aged raw pseudo-boehmite; passing the aged raw pseudo-boehmite through a cation exchange resin at a set flow rate to remove metal ion impurities from the aged raw pseudo-boehmite; and drying the raw pseudo-boehmite from which the metal ion impurities have been removed to obtain a low-impurity pseudo-boehmite, wherein the metal ion impurity content is ≤0.1% by weight. The apparatus comprises a first container, a second container, a third container, and a drying device. The method and apparatus can reduce the metal ion impurity content of the produced low-impurity pseudo-boehmite to ≤0.1% by weight.

[0005] CN201110103785.1 discloses a method for producing ultrafine aluminum hydroxide and aluminum oxide from fly ash. The method comprises: a) crushing the fly ash, performing wet magnetic separation to remove iron, and then reacting it with hydrochloric acid to produce a hydrochloric acid extract; b) passing the hydrochloric acid extract through a macroporous cationic resin column for adsorption. After the resin is saturated with adsorption, eluting it with an eluent to produce an eluent containing aluminum chloride and ferric chloride; c) subjecting the eluent to alkaline dissolution to remove iron, producing a sodium aluminate solution; d) adding a dispersant to the sodium aluminate solution and mixing it uniformly to produce a dispersion; e) reacting the dispersion with carbon dioxide for neutralization, washing it with water and ethanol, and drying it to produce ultrafine aluminum hydroxide. This process uses the cationic resin to primarily adsorb aluminum and iron ions, utilizing only the adsorption properties of the cationic resin. Summary of the Invention

[0006] In response to the shortcomings of the prior art, the present invention provides alumina and a method for preparing the same. This method eliminates the washing step in existing methods, significantly reducing wastewater discharge and optimizing the entire preparation process. Furthermore, the resulting alumina exhibits a high specific surface acidity, a large pore volume, and excellent hydraulic hardness.

[0007] The first aspect of the present invention provides an aluminum oxide, wherein the aluminum oxide is phosphorus-containing aluminum oxide, and has the following properties: a pore volume of 0.7 to 1.2 mL / g, preferably 0.8 to 1.1 mL / g, more preferably 0.9 to 1.1 mL / g, a phosphorus content of 0.3 wt% to 5.0 wt%, preferably 0.5 wt% to 4.5 wt%, and a unit surface acidity of 0.001 to 0.002 mmol / m 2 , preferably 0.0015~0.002mmol / m 2 The hydraulic hardness is 3 to 10 N / grain, preferably 5 to 10 N / grain.

[0008] The alumina of the present invention may further contain an additive, which may be one or more of Si, B, and Ti. The additive content is 1 wt% to 8 wt% in terms of oxide.

[0009] A second aspect of the present invention provides a method for preparing aluminum oxide, the method comprising the following steps:

[0010] (1) Add bottom water to the reactor, heat it to a certain temperature under stirring, and then add sodium aluminate solution, phosphate surfactant solution and cation exchange resin suspension to react;

[0011] (2) aging the slurry obtained from the reaction in step (1), and adding a cation exchange resin after aging;

[0012] (3) The material obtained in step (2) is separated, and the separated slurry is filtered, dried and calcined to obtain alumina.

[0013] In the method for preparing aluminum oxide of the present invention, the bottom water in step (1) is deionized water, and the amount of deionized water added is 5 to 20% of the volume of the reactor, preferably 5 to 15%.

[0014] In the method for preparing alumina according to the present invention, the sodium aluminate solution, the phosphate surfactant, and the cation exchange resin in step (1) can be added simultaneously in parallel flow or separately into the reactor, preferably simultaneously in parallel flow. When added separately into the reactor, there is no particular restriction on the order in which the materials are added, but preferably the sodium aluminate solution and the phosphate surfactant are added first, followed by the cation exchange resin.

[0015] In the method for preparing alumina of the present invention, the caustic ratio of the sodium aluminate solution in step (1) is 1.15 to 1.35, preferably 1.20 to 1.30, and the concentration of the sodium aluminate solution is 20 to 100 gAl2O3 / L, preferably 30 to 70 gAl2O3 / L, calculated as oxide. The flow rate of the sodium aluminate solution added to the reactor is 20 mL / min to 60 mL / min, preferably 30 mL / min to 50 mL / min;

[0016] In the method for preparing alumina according to the present invention, the phosphate surfactant in step (1) is an anionic phosphate surfactant and / or an amphoteric phosphate surfactant, preferably an anionic phosphate surfactant. The phosphate surfactant is an alkyl phosphate and / or a polyether phosphate, specifically one or more of C9-C15 monoalkyl ether phosphate, C9-C15 alkyl phosphate, and C9-C15 dialkyl phosphate, preferably C9-C15 monoalkyl ether phosphate, and more preferably C9 monoalkyl ether phosphate. The concentration of the phosphate surfactant solution is 0.05-0.5 g / mL, and the flow rate of the phosphate surfactant added to the reactor is 5 mL / min-10 mL / min.

[0017] In the method for preparing alumina of the present invention, the cation exchange resins described in steps (1) and (2) are strong acid cation exchange resins, preferably one or more of a macroporous strongly acidic styrene-based cation exchange resin and a sulfonated styrene-based gel-type strongly acidic cation exchange resin. The macroporous strongly acidic styrene-based cation exchange resin may be one or more of a D001 macroporous strongly acidic styrene-based cation exchange resin, a D002 macroporous strongly acidic styrene-based cation exchange resin, and a D61 macroporous strongly acidic styrene-based cation exchange resin; more preferably, one or two of a D001 macroporous strongly acidic styrene-based cation exchange resin and a D61 macroporous strongly acidic styrene-based cation exchange resin. The particle size of the cation exchange resin is 40 to 80 mesh.

[0018] In the method for preparing alumina according to the present invention, the solid content of the cation exchange resin suspension in step (1) is 30 wt% to 80 wt%, preferably 50 wt% to 80 wt%. The addition rate of the cation exchange resin suspension can be adjusted according to the pH value of the slurry in the reactor.

[0019] In the method for preparing alumina of the present invention, the temperature of the slurry in the reactor in step (1) is 45°C to 80°C, preferably 50°C to 75°C; the pH value of the slurry is 7.5 to 10, preferably 8.0 to 9.5.

[0020] In the method for preparing alumina of the present invention, the sodium aluminate solution in step (1) can be prepared by mixing aluminum hydroxide and sodium hydroxide and boiling them together to form a solution with a concentration of 300 to 400 gAl2O3 / L, and then diluting it to the required concentration with an aqueous solution containing 1 wt% to 5 wt% NaOH.

[0021] In the method for preparing aluminum oxide of the present invention, the aging temperature in step (2) is 50 to 100° C., preferably 60 to 90° C., and the aging time is 0.5 to 3 h, preferably 1 to 2 h.

[0022] In the method for preparing alumina of the present invention, a cation exchange resin is added after aging in step (2), and the cation exchange resin is used to adjust the pH value of the slurry to 6.0 to 7.5, preferably 6.5 to 7.0.

[0023] In the method for preparing alumina according to the present invention, the separation in step (3) comprises separating the cation exchange resin from the slurry using a 100-120 mesh screen, and regenerating and recycling the separated cation exchange resin; filtering the separated slurry to separate the filter cake and the filtrate, drying the filter cake, and recycling the filtrate. The drying temperature in step (3) is 100-150° C., and the drying time is 6-10 hours.

[0024] In the method for preparing alumina of the present invention, the calcination temperature in step (3) is 500-900° C., and the calcination time is 2-8 hours.

[0025] In the method for preparing alumina of the present invention, an auxiliary agent may be added as needed, such as a precursor of one or more of SiO2, B2O3, and TiO2. The precursor is added during the reaction of step (1) in the form of a water-soluble inorganic salt, such as a silicate, phosphate, borate, sulfate, or nitrate. The amount of auxiliary agent added may be based on the requirements of the catalyst. Generally, the weight content of the auxiliary agent as oxide may be 2% to 6%.

[0026] The third aspect of the present invention provides aluminum oxide prepared by the above method.

[0027] In the above-mentioned alumina, the alumina is phosphorus-containing alumina, and its properties are as follows: pore volume of 0.7 to 1.2 mL / g, preferably 0.8 to 1.1 mL / g, more preferably 0.9 to 1.1 mL / g, P content of 0.3 wt% to 5.0 wt%, preferably 0.5 wt% to 4.5 wt%, unit surface acidity of 0.001 to 0.002 mmol / m 2 , preferably 0.0015~0.002mmol / m 2 The hydraulic hardness is 3 to 10 N / grain, preferably 5 to 10 N / grain.

[0028] The above-mentioned aluminum oxide further includes an additive, which may be one or more of Si, B, and Ti. The additive content is 1 wt% to 8 wt% in terms of oxide.

[0029] Compared with the prior art, the alumina and preparation method thereof of the present invention have the following advantages:

[0030] (1) The present invention provides an alumina having a large pore volume, low impurity content, high surface acidity per unit area, and good water hardness, and is suitable for preparing a hydrogenation catalyst carrier having good anti-wear performance.

[0031] (2) In the preparation method of alumina of the present invention, by adding a strong acidic cation exchange resin and a phosphate surfactant in the first synthesis reaction, sodium ions can be effectively adsorbed while the reaction is completed, greatly reducing the sodium ion encapsulation of the pseudo-boehmite. Under the joint action of the phosphate surfactant and the cation exchange resin, the effective separation of the pseudo-boehmite and the resin can be effectively promoted, which can ensure that the pseudo-boehmite with a low sodium content is obtained, and the surface acidity of the prepared alumina product can be further improved.

[0032] (3) In the alumina preparation method of the present invention, the sodium content in the prepared pseudo-boehmite sample can be greatly reduced by adding a strong acidic cation exchange resin in steps, thereby obtaining a pseudo-boehmite product with a low sodium content. The washing process can also be omitted, and the slurry can be recycled after filtration. The preparation method realizes a closed-loop production process and eliminates the emission of pollutants. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further illustrated below with reference to the following examples, but is not limited to the following examples. In the present invention, wt% refers to mass fraction.

[0034] In the examples and comparative examples of the present invention, water hardness refers to the property of reacting with water and gradually solidifying and hardening in a humid medium. The water hardness of aluminum oxide in the examples and comparative examples of the present invention is defined as the strength of the sample after aluminum oxide agglomerates and solidifies into particles after encountering atomized water droplets, and is dried at 200°C for 3 hours, in units of N / particle. The specific measurement process includes the following: (1) Weigh 100g of the prepared aluminum oxide sample, add 50g of water, and spray small water droplets in an atomizer with a nozzle of 100 microns. After the aluminum oxide absorbs the small water droplets, it gradually aggregates and further crystallizes to solidify and harden into small balls. Due to the different microscopic properties of aluminum oxide, the solidification and hardening time is different. The water hardness of aluminum oxide with a short solidification time is better than that with a long solidification time; (2) After the solidified aluminum oxide balls are dried at 200°C for 3 hours, the aluminum oxide balls with a size of 1.0 to 1.5 mm are selected, and the pressure of 20 samples is tested with an intelligent strength meter, in units of N, and the average strength is in units of N / particle.

[0035] In the Examples and Comparative Examples of the present invention, the pore volume and specific surface area of ​​the alumina were analyzed using low-temperature nitrogen adsorption. P content was measured using spectrophotometry, and Na content was measured using inductively coupled plasma emission spectroscopy (ICP). Infrared acidity was measured using an infrared spectrometer, using pyridine as the adsorbent.

[0036] Example 1

[0037] Aluminum hydroxide and sodium hydroxide are mixed and boiled together to form a solution with a concentration of 345gAl2O3 / L, which is then diluted with a 3.5wt% NaOH aqueous solution to prepare a sodium aluminate solution with a caustic ratio of 1.20 and a concentration of 50gAl2O3 / L for later use; a C9 monoalkyl ether phosphate solution with a concentration of 0.2g / mL is prepared for later use; and a D001 macroporous strongly acidic styrene-based cation exchange resin with a mesh size of 60 is prepared into a suspension with a solid content of 50wt% for later use.

[0038] A 500mL reactor was filled with 500mL of deionized water as bottom water. Stirring and heating were initiated. After the deionized water was heated to 50°C, the three materials were added to the reactor in parallel. The flow rates of the sodium metaaluminate and the C9 monoalkyl ether phosphate solution were controlled at 30mL / min and 6mL / min, respectively. The pH of the slurry in the reactor was controlled to 8.0 by adjusting the flow rate of the D001 macroporous, strongly acidic styrene-based cation exchange resin suspension. The slurry temperature and pH were maintained constant. After the reaction, the resulting slurry was aged at 90°C for 2h and then adjusted to a pH of 7.0 using the D001 macroporous, strongly acidic styrene-based cation exchange resin suspension. A 100-mesh screen was used to separate the cation exchange resin from the slurry, and the separated cation exchange resin was regenerated and recycled. The slurry is filtered to separate the filter cake and the filtrate, and the filtrate can be recycled. The obtained filter cake is dried at 120°C for 8 hours and calcined at 600°C for 3 hours to obtain the aluminum oxide A1 of the present invention. Its properties are shown in Table 1.

[0039] Example 2

[0040] Other conditions were the same as in Example 1, except that the concentration of the sodium metaaluminate solution was adjusted to 65 gAl2O3 / L and the gelling temperature was adjusted to 70°C to obtain alumina A2, the properties of which are shown in Table 1.

[0041] Example 3

[0042] Other conditions were the same as those in Example 1, except that the 60-mesh D001 macroporous strongly acidic styrene-based cation exchange resin was replaced with the 80-mesh D61 macroporous strongly acidic styrene-based cation exchange resin, the gelling pH was adjusted to 9.0, and the drying conditions were changed to drying at 150° C. for 6 h to obtain alumina A3, the properties of which are shown in Table 1.

[0043] Example 4

[0044] Other conditions were the same as in Example 1, except that C9 monoalkyl ether phosphate was replaced with C9 alkyl phosphate. The pH value was adjusted to 6.5 after aging to obtain aluminum oxide A4, the properties of which are shown in Table 1.

[0045] Example 5

[0046] Other conditions were the same as in Example 1, except that the flow rate of sodium aluminate was changed to 45 mL / min, the concentration of the C9 monoalkyl ether phosphate solution was changed to 0.1 g / mL, and the flow rate was changed to 8 mL / min to obtain alumina A5, the properties of which are shown in Table 1.

[0047] Comparative Example 1

[0048] Aluminum hydroxide and sodium hydroxide are mixed and boiled together to prepare a solution with a concentration of 345gAl2O3 / L, and then diluted with a 3.5wt% NaOH aqueous solution to prepare a sodium aluminate solution with a caustic ratio of 1.20 and a concentration of 50gAl2O3 / L for standby use; a C9 monoalkyl ether phosphate solution with a concentration of 0.2g / mL is prepared for standby use.

[0049] A 500 mL reactor was filled with 500 mL of deionized water as the bottom water. Stirring and heating were initiated. After the deionized water was heated to 50°C, the two liquids were added concurrently to the reactor. The flow rates of the sodium metaaluminate and the C9 monoalkyl ether phosphate solution were controlled at 30 mL / min and 6 mL / min, respectively, while maintaining a constant slurry temperature within the reactor. After the reaction, the resulting slurry was aged at 90°C for 2 hours. The slurry was then filtered to separate the filter cake and filtrate. The filter cake was washed with distilled water to a pH of 7.0. The resulting filter cake was dried at 120°C for 8 hours and calcined at 600°C for 3 hours to obtain Comparative Example Alumina B1. Its properties are shown in Table 2.

[0050] Comparative Example 2

[0051] Aluminum hydroxide and sodium hydroxide are mixed and boiled together to prepare a solution with a concentration of 345gAl2O3 / L, which is then diluted with a 3.5wt% NaOH aqueous solution to prepare a sodium aluminate solution with a caustic ratio of 1.20 and a concentration of 50gAl2O3 / L for later use; D001 macroporous strong acid styrene cation exchange resin with a mesh size of 60 mesh is prepared into a suspension with a solid content of 50% for later use.

[0052] A 500 mL reactor was filled with 500 mL of deionized water as the bottom water. Stirring and heating were initiated. After the deionized water was heated to 50°C, the two liquids were added concurrently to the reactor. The sodium metaaluminate flow rate was controlled at 30 mL / min. The pH of the slurry in the reactor was maintained at 8.0 by adjusting the flow rate of the D001 macroporous, strongly acidic styrene cation exchange resin suspension. The slurry temperature and pH were maintained constant. After the reaction, the resulting slurry was aged at 90°C for 2 hours and then adjusted to a pH of 7.0 using the cation exchange resin suspension. The cation exchange resin was separated from the slurry using a 100-mesh sieve, and the separated cation exchange resin was regenerated and recycled. The slurry was filtered to separate the filter cake and filtrate, which was recycled. The resulting filter cake was dried at 120°C for 8 hours and calcined at 600°C for 3 hours to obtain Comparative Example Alumina B2. Its properties are shown in Table 2.

[0053] Comparative Example 3

[0054] Aluminum hydroxide and sodium hydroxide are mixed and boiled together to prepare a solution with a concentration of 345gAl2O3 / L, and then diluted with a 3.5wt% NaOH aqueous solution to prepare a sodium aluminate solution with a caustic ratio of 1.20 and a concentration of 25gAl2O3 / L for standby use.

[0055] The sodium metaaluminate solution was added to a 5000 mL reactor, and a mixture of CO2 and air was introduced into the reactor. The slurry temperature in the reactor was controlled to be constant at 22°C. The reaction was terminated when the pH of the slurry in the reactor was 10.5. The mixture was filtered, and the filter cake was washed with deionized water 60 times the amount of deionized water produced until neutral. The mixture was dried at 120°C for 8 hours and calcined at 600°C for 3 hours to obtain comparative example alumina B3, the properties of which are shown in Table 2.

[0056] Comparative Example 4

[0057] Aluminum hydroxide and sodium hydroxide are mixed and boiled together to prepare a solution with a concentration of 345gAl2O3 / L, and then diluted with a 3.5wt% NaOH aqueous solution to prepare a sodium aluminate solution with a caustic ratio of 1.20 and a concentration of 150gAl2O3 / L for standby use; an aluminum sulfate solution with a concentration of 50gAl2O3 / L is prepared for standby use.

[0058] 500 mL of deionized water was added to a 5000 mL reactor as the bottom water. Stirring and heating were initiated. After the deionized water was heated to 50°C, the two solutions were added to the reactor in parallel. The flow rate of the sodium metaaluminate was controlled at 30 mL / min. The pH of the slurry in the reactor was controlled to 8.0 by adjusting the flow rate of the aluminum sulfate solution, and the temperature and pH of the slurry in the reactor were maintained constant. After the reaction, the resulting slurry was aged at 90°C for 2 hours. After aging, it was filtered and the filter cake was washed with deionized water 80 times the volume of the generated pseudo-boehmite until neutral. The mixture was dried at 120°C for 8 hours and calcined at 600°C for 3 hours to obtain the alumina B4 of the present invention. Its properties are shown in Table 2.

[0059] Table 1 Properties of the aluminum oxides prepared in Examples 1-5

[0060] serial number Example 1 Example 2 Example 3 Example 4 Example 5 Pore ​​volume, mL / g 1.03 1.00 1.04 1.06 0.99 <![CDATA[Specific surface area, m 2 / g]]> 274 283 281 266 301 <![CDATA[Unit surface acid amount, mmol / m 2 > 0.0017 0.0016 0.0016 0.0015 0.0013 P, wt% 2.08 2.09 2.08 2.10 0.94 Na, wt% 0.02 0.03 0.02 0.01 0.02 Hydraulic hardness, N / grain 7.1 6.4 6.6 7.3 6.1

[0061] Table 2 Properties of Alumina Prepared in Comparative Examples 1-4

[0062] serial number Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Pore ​​volume, mL / g 0.15 0.85 0.95 0.98 <![CDATA[Specific surface area, m 2 / g]]> 80 321 310 298 <![CDATA[Unit surface acid amount, mmol / m 2 > 0.0005 0.0007 0.0008 0.0007 P, wt% 3.18 - - - Na, wt% 3.92 1.11 0.04 0.04 Hydraulic hardness, N / grain 0.1 3.5 1.5 1.8

[0063] It can be seen from the data in the table that the alumina prepared by the method of the present invention has a large pore volume, a high acid content per unit surface area, a low impurity content, and good water hardness, and is particularly suitable for preparing hydrogenation catalysts.

Claims

1. A method for preparing aluminum oxide, comprising the following steps: (1) Add bottom water to the reactor, heat it to a certain temperature under stirring, and then add sodium aluminate solution, phosphate surfactant solution and cation exchange resin suspension to react; (2) aging the slurry obtained from the reaction in step (1), and adding a cation exchange resin after aging; (3) The material obtained in step (2) is separated, and the separated slurry is filtered, dried and calcined to obtain alumina.

2. The method for preparing aluminum oxide according to claim 1, wherein: The bottom water in step (1) is deionized water, and the amount added is 5-20% of the reactor volume.

3. The method for preparing aluminum oxide according to claim 1 or 2, characterized in that: The bottom water in step (1) is deionized water, and the amount added is 5-15% of the reactor volume.

4. The method for preparing aluminum oxide according to claim 1, wherein: The caustic ratio of the sodium aluminate solution in step (1) is 1.15 to 1.35, and the concentration of the sodium aluminate solution is 20 to 100 gAl2O3 / L, calculated as oxide.

5. The method for preparing aluminum oxide according to claim 1 or 4, characterized in that: The caustic ratio of the sodium aluminate solution in step (1) is 1.20-1.30, and the concentration of the sodium aluminate solution is 30-70 gAl2O3 / L, calculated as oxide.

6. The method for preparing aluminum oxide according to claim 1, wherein: In step (1), the flow rate of adding the sodium aluminate solution into the reactor is 20 mL / min to 60 mL / min.

7. The method for preparing aluminum oxide according to claim 1 or 6, characterized in that: In step (1), the flow rate of adding the sodium aluminate solution into the reactor is 30 mL / min to 50 mL / min.

8. The method for preparing aluminum oxide according to claim 1, wherein: The phosphate surfactant in step (1) is an anionic phosphate surfactant and / or an amphoteric phosphate surfactant.

9. The method for preparing aluminum oxide according to claim 1 or 8, characterized in that: The phosphate surfactant in step (1) is an anionic phosphate surfactant.

10. The method for preparing aluminum oxide according to claim 1 or 8, characterized in that: The phosphate surfactant in step (1) is an alkyl phosphate and / or a polyether phosphate.

11. The method for preparing aluminum oxide according to claim 1 or 8, characterized in that: The phosphate surfactant in step (1) is one or more of C9-C15 monoalkyl ether phosphate, C9-C15 alkyl phosphate, and C9-C15 dialkyl phosphate.

12. The method for preparing aluminum oxide according to claim 1 or 8, characterized in that: The phosphate surfactant in step (1) is a C9-C15 monoalkyl ether phosphate.

13. The method for preparing aluminum oxide according to claim 1 or 8, characterized in that: In step (1), the phosphate surfactant is a C9 monoalkyl ether phosphate.

14. The method for preparing aluminum oxide according to claim 1, characterized in that: The concentration of the phosphate surfactant solution is 0.05-0.5 g / mL, and the flow rate of the phosphate surfactant added into the reactor is 5 mL / min-10 mL / min.

15. The method for preparing aluminum oxide according to claim 1, characterized in that: The cation exchange resins described in step (1) and step (2) are strong acid cation exchange resins.

16. The method for preparing aluminum oxide according to claim 1 or 15, characterized in that: The cation exchange resins described in step (1) and step (2) are one or more of macroporous strongly acidic styrene-based cation exchange resins and sulfonated styrene-based gel-type strongly acidic cation exchange resins.

17. The method for preparing aluminum oxide according to claim 16, characterized in that: The macroporous strongly acidic styrene-based cation exchange resin is one or more of D001 macroporous strongly acidic styrene-based cation exchange resin, D002 macroporous strongly acidic styrene-based cation exchange resin and D61 macroporous strongly acidic styrene-based cation exchange resin.

18. The method for preparing aluminum oxide according to claim 16, characterized in that: The macroporous strongly acidic styrene-based cation exchange resin is one or both of D001 macroporous strongly acidic styrene-based cation exchange resin and D61 macroporous strongly acidic styrene-based cation exchange resin.

19. The method for preparing aluminum oxide according to claim 1 or 15, characterized in that: The particle size of the cation exchange resin is 40 to 80 meshes.

20. The method for preparing aluminum oxide according to claim 1, characterized in that: The solid content of the cation exchange resin suspension in step (1) is 30 wt% to 80 wt%.

21. The method for preparing aluminum oxide according to claim 1 or 20, characterized in that: The solid content of the cation exchange resin suspension in step (1) is 50 wt% to 80 wt%.

22. The method for preparing aluminum oxide according to claim 1, characterized in that: In step (1), the temperature of the slurry in the reactor is 45°C to 80°C, and the pH value of the slurry is 7.5 to 10.

23. The method for preparing aluminum oxide according to claim 1 or 22, characterized in that: In step (1), the slurry temperature in the reactor is 50° C. to 75° C., and the slurry pH is 8.0 to 9.

5.

24. The method for preparing aluminum oxide according to claim 1, characterized in that: In step (2), the aging temperature is 50-100° C., and the aging time is 0.5-3 h.

25. The method for preparing aluminum oxide according to claim 1 or 24, characterized in that: In step (2), the aging temperature is 60-90° C., and the aging time is 1-2 h.

26. The method for preparing aluminum oxide according to claim 1, characterized in that: After aging in step (2), a cation exchange resin is added to adjust the pH value of the slurry to 6.0-7.5 by the cation exchange resin.

27. The method for preparing aluminum oxide according to claim 1 or 26, characterized in that: After aging in step (2), a cation exchange resin is added to adjust the pH value of the slurry to 6.5-7.0 by the cation exchange resin.

28. The method for preparing aluminum oxide according to claim 1, characterized in that: The drying temperature in step (3) is 100-150° C., and the drying time is 6-10 hours.

29. The method for preparing aluminum oxide according to claim 1, characterized in that: The calcination temperature in step (3) is 500-900° C., and the calcination time is 2-8 hours.

30. Aluminum oxide, characterized in that: The alumina is prepared by the method according to any one of claims 1 to 29, and the alumina is phosphorus-containing alumina, and its properties are as follows: a pore volume of 0.7 to 1.2 mL / g, a phosphorus content of 0.3 wt% to 5.0 wt%, and a unit surface acidity of 0.001 to 0.002 mmol / m 2 The hydraulic hardness is 3 to 10 N / particle. The hydraulic hardness is defined as the strength of the sample after aluminum oxide agglomerates and solidifies into particles after encountering atomized water droplets and is dried at 200°C for 3 hours.

31. Aluminum oxide according to claim 30, characterized in that: The pore volume is 0.8-1.1 mL / g, the P content is 0.5 wt%-4.5 wt%, and the unit surface acidity is 0.0015-0.002 mmol / m 2 , the water hardness is 5~10N / grain.

32. Aluminum oxide according to claim 30, characterized in that: The pore volume is 0.9~1.1mL / g.