Calcium aluminate material and method for its production

Abstract

This invention relates to the field of catalysts, and discloses a calcium aluminate material and its preparation method. The calcium aluminate material of this invention exhibits a diffraction peak intensity I at 25.4°. 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Satisfy I 25.4° / I 57.5° ≥1.5 and I 30.1° / I 57.5° ≤0.5. The calcium aluminate material prepared by the method of the present invention has a special crystal phase composition and physical properties, and can be used as a catalyst support for hydrocarbon catalytic conversion (natural gas steam catalytic conversion, natural gas carbon dioxide dry gas catalytic conversion, natural gas partial oxidation conversion, steam carbon dioxide co-conversion, etc.), and as a catalyst for alkaline catalytic reactions such as heavy oil pyrolysis-gasification coupled hydrogen production and transesterification.

Description

Technical Field

[0001] This invention relates to the field of catalysts and their preparation technology, specifically to a calcium aluminate material and its preparation method. Background Technology

[0002] Calcium aluminate, as a special hydraulic material, has long been known and widely used in the production of high-performance (low water content, low cement content) refractory castables.

[0003] Typically, pure calcium aluminate refractory cement is a cementitious material made by mixing industrial alumina powder and high-quality limestone in a certain proportion, crushing and grinding them, pressing them into rough blanks, calcining them at high temperatures, and then crushing and grinding them again. Its main mineral components are monocalcium aluminate (CA2), monocalcium aluminate (CA), monocalcium hexaaluminate (CA6), and α-alumina (α-Al2O3). Due to the high Al2O3 content in calcium aluminate cement, the content of calcium and impurities is correspondingly reduced, resulting in a refractoriness of over 1690℃. Refractory castables prepared with pure calcium aluminate refractory cement have excellent high-temperature performance, including high refractoriness, good thermal shock resistance, and good resistance to slag erosion. They are suitable for refractory linings and refractory furnace materials in high-temperature kilns and thermal equipment in the cement, chemical, and metallurgical industries. Compared with refractory bricks, refractory castables prepared with it have advantages such as simple manufacturing process and convenient construction, making them suitable for on-site construction in any location and shape. They can also be used to manufacture large precast products to meet various application needs.

[0004] The main chemical components of calcium aluminate are α-Al₂O₃ and CaO. In the CaO-Al₂O₃ binary system, C₃A and C₂O are present. 12 Five compounds, A7, CA, CA2, and CA6, were involved. Conventionally synthesized calcium aluminate materials typically contain multiple crystalline phases and have a low specific surface area. For example, as reported in the literature (Yang Qing, Preparation of Pure Calcium Aluminate Special Cement by Sintering Method [J]. Cement, 1992(9):27-28), the synthesized calcium aluminate special cement contains approximately 73% CA2 and 27% CA, with a specific surface area of ​​approximately 0.6 m². 2 / g. The literature (Li Youqi, Li Yawei, Jin Shengli, et al. Synthesis and microstructure study of calcium hexaaluminate materials [J]. Refractory Materials, 2004, 38(5):318-323) synthesized refractory materials with CA6 as the main crystalline phase using active α-Al2O3 and CaCO3. The literature (Li Youqi, Ke Changming, Li Nan. Synthesis and microstructure study of calcium dialuminate with low expansion coefficient [J]. Materials Reports, 2006, 20(F05):470-472) reported that pure CA2 materials were synthesized by reaction sintering using active α-Al2O3 and CaCO3, with the content of CaO and Al2O3 in the feed according to the stoichiometric ratio of CA2, i.e., m(CaO):m(Al2O3) of 27.45:100. The literature (Zeng Chunyan, Yi Shuai, Liu Yangai, et al. Effect of CaO and γ-Al2O3 ratio on the synthesis of crystalline calcium hexaaluminate [J]. Refractory Materials, 2011, 45(002): 85-88) reported that using CaO and γ-Al2O3, nearly pure CA6 material could be synthesized at the theoretical ratio of CA6, while when the feedstock was rich in calcium, the synthesized product contained a small amount of monocalcium dialuminate (CA2). The literature (Chen Feng, Hong Yanruo, Sun Jialin, et al. Chemical synthesis of high-purity calcium aluminate powder [J]. Refractory Materials, 2004, 38(4): 245-348) used saturated Ca(OH)2 solution and AlCl3 solution as initial raw materials, and adopted the co-precipitation method at room temperature, in Al 3+ With Ca 2+ Under the condition of a molar ratio of approximately 2.2, a precursor of calcium aluminate hydrate precipitate was first synthesized, and then calcined at low temperature to prepare a binary mixture of calcium aluminate powder with high activity, high purity, CA as the main crystalline phase and a small amount of CA2.

[0005] As mentioned above, calcium aluminate, as a special high-temperature resistant material, has been widely used and attracted attention in the cement, ceramics and metallurgical industries. In addition, it can also be used as an alkaline catalyst and support material (①Wang Sihan, Zhang Yujian. Research status of hydrogen production technology by steam reforming of natural gas[J]. Industrial Catalysis, 2016, 24(4):26-30; ②Wang Rongbin. Calcium aluminate catalytic heavy oil cracking-gasification process[J]. Acta Petrolei Sinica (Petroleum Processing), 2021, 37(2):384-390). As a catalyst support for the conversion of natural gas into syngas, calcium aluminate has been applied in industry (①Huang Zhongtao. Handbook of Industrial Catalysts[M]. Chemical Industry Press, 2004, p676; ②Shen Wenjie. Industrial application of CN-20 type catalyst[J]. Natural Gas Chemical Industry, 2002, 27(1):19-25).

[0006] It is known that, whether used as ceramic materials or catalytic materials, the crystal phase composition and specific surface area of ​​different materials have a significant impact on their performance. Most calcium aluminate materials reported in the literature have relatively small specific surface areas (mostly less than 1 m²).2 / g), and there are few reports on materials with CA2 as the main crystalline phase. Summary of the Invention

[0007] The purpose of this invention is to provide a calcium aluminate material with a main crystalline phase of calcium aluminate (CA2), containing a small amount of α-Al2O3, and having high lateral compressive strength, water absorption rate, and specific surface area, as well as a method for preparing the same.

[0008] To achieve the above objectives, the present invention provides a calcium aluminate material comprising monocalcium disodium aluminate and α-Al₂O₃. In powder XRD diffraction analysis, the calcium aluminate material exhibits a diffraction peak intensity I at 25.4°. 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Satisfying the following formulas (1) and (2),

[0009] I 25.4° / I 57.5° ≥1.5 formula (1),

[0010] I 30.1° / I 57.5° ≤0.5 formula (2).

[0011] Preferably, in powder XRD diffraction analysis, the diffraction peak intensity I of the calcium aluminate material at 25.4° is... 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Satisfy the following formulas (3) and (4),

[0012] I 25.4° / I 57.5° ≥2.5 formula (3),

[0013] I 30.1° / I 57.5° ≤0.2 formula (4).

[0014] The specific surface area of ​​the calcium aluminate material is 1-5 m². 2 / g, preferably 2-4m 2 / g, more preferably 3-4m 2 / g.

[0015] According to a second aspect of the present invention, a method for preparing calcium aluminate material is provided, wherein the method comprises the following steps:

[0016] 1) In the presence of a solvent, alumina raw materials and calcium oxide raw materials are mixed and ground, and the ground products are dried and sieved;

[0017] 2) After the sieved product comes into contact with the release agent, it is then shaped and fired.

[0018] In the grinding process, the mixture is ground to D(50)≤30μm, and the sieving process allows the dried product to pass through a 10-25 mesh sieve.

[0019] Preferably, the alumina raw material is selected from one or more of hydrated alumina, transition phase alumina and α-alumina, and more preferably hydrated alumina.

[0020] Preferably, the hydrated alumina is selected from one or more of α-gibbsite, boehmite, and gibbsite, and more preferably α-gibbsite.

[0021] Preferably, the calcium oxide raw material is selected from one or more of calcium hydroxide, calcium oxide and calcium carbonate, and is preferably calcium carbonate.

[0022] Preferably, the solvent is one or more of water, ethanol, acetone, ethylene glycol and methanol, with water being the most preferred.

[0023] Preferably, the mass ratio of the solvent, alumina raw material and calcium oxide raw material is 1:0.4-0.9:0.1-0.23.

[0024] Preferably, the amount of the alumina raw material is 80-92% by weight of the calcium aluminate material, more preferably 82-90% by weight.

[0025] Preferably, in the grinding process, the mixture is ground to D(50)≤20μm, and more preferably D(50)≤15μm.

[0026] Preferably, the drying conditions include a temperature of 50-300℃ and a time of 0.1-24h; more preferably, a temperature of 60-150℃ and a time of 1-8h.

[0027] Preferably, the mass ratio of the release agent to the calcium oxide raw material is 0.02-0.6:1; more preferably, it is 0.05-0.5:1.

[0028] Preferably, the release agent is selected from one or more of starch, graphite, coke, stearic acid and stearate, more preferably one or more of stearate, graphite and coke.

[0029] Preferably, a molding aid is added during the contact process.

[0030] Preferably, the molding aid is selected from one or more of water, nitric acid, ethanol and ethylene glycol.

[0031] Preferably, the molding process can be sheet molding, extrusion molding, or ball rolling molding, with sheet molding being the most preferred.

[0032] The roasting conditions include: a temperature of 1200-1500℃ and a time of 1-8h; preferably, a temperature of 1250-1450℃ and a time of 2-6h.

[0033] According to a third aspect of the present invention, a calcium aluminate material prepared by the method for preparing the calcium aluminate material according to the second aspect of the present invention is provided.

[0034] Through the above technical solution, the present invention can provide a calcium aluminate material with calcium dialuminate (CA2) as the main crystalline phase, containing a small amount of α-Al2O3, and having high lateral compressive strength, water absorption rate and specific surface area, as well as a method for preparing the same.

[0035] The diffraction peak intensity I of the calcium aluminate material provided in the first aspect of the present invention at 25.4° 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Satisfy I 25.4° / I 57.5° ≥1.5 and I 30.1° / I 57.5° With a strength of ≤0.5, its compressive strength, water absorption rate, and specific surface area are higher than other calcium aluminate materials (whose main crystalline phase is calcium dialuminate (CA2)).

[0036] When preparing calcium aluminate material using the method provided in the second aspect of this invention, grinding the mixture to a density of D(50) ≤ 30 μm and sieving the dried product to pass through a 10-25 mesh sieve are important methods for controlling the crystal phase, so that the diffraction peak intensity I at 25.4° of the final obtained calcium aluminate material is... 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Satisfy I 25.4° / I 57.5° ≥1.5 and I 30.1° / I 57.5° ≤0.5.

[0037] The calcium aluminate material provided in the third aspect of this invention has a surface area as high as 3-4 m². 2The density of this calcium aluminate material is higher than that of other calcium aluminate materials (whose main crystalline phase is calcium dialuminate (CA2)). It also has higher compressive strength and better water absorption. Therefore, when this calcium aluminate material is used as a catalyst support for hydrocarbon catalytic conversion (natural gas steam catalytic conversion, natural gas carbon dioxide dry gas catalytic conversion, natural gas partial oxidation conversion, steam carbon dioxide co-conversion, etc.), or as a catalyst for alkaline catalytic reactions such as heavy oil pyrolysis-gasification coupled hydrogen production and transesterification, it has the advantages of better stability and resistance to high temperature and high pressure. Attached Figure Description

[0038] Figure 1 This is the XRD pattern of Example 1.

[0039] Figure 2 This is the XRD pattern of Comparative Example 1.

[0040] Figure 3 This is the XRD pattern of Comparative Example 2. Detailed Implementation

[0041] 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.

[0042] According to a first aspect of the present invention, a calcium aluminate material is provided, wherein the calcium aluminate material comprises monocalcium disodium aluminate and α-Al₂O₃, and in powder XRD diffraction analysis, the diffraction peak intensity I of the calcium aluminate material at 25.4° is... 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Satisfying the following formulas (1) and (2),

[0043] I 25.4° / I 57.5° ≥1.5 formula (1),

[0044] I 30.1° / I 57.5° ≤0.5 formula (2).

[0045] According to the present invention, preferably, in powder XRD diffraction analysis, the diffraction peak intensity I of the calcium aluminate material at 25.4° is... 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Satisfy the following formulas (3) and (4),

[0046] I 25.4° / I 57.5° ≥2.5 formula (3),

[0047] I 30.1° / I 57.5° ≤0.2 formula (4).

[0048] According to the present invention, preferably, the specific surface area of ​​the calcium aluminate material can be 1-5 m². 2 / g, more preferably, the specific surface area of ​​the calcium aluminate material is 2-4m² / g. 2 / g; more preferably, the specific surface area of ​​the calcium aluminate material is 3-4m². 2 / g.

[0049] According to a second aspect of the present invention, a method for preparing calcium aluminate material is provided, wherein the method comprises the following steps:

[0050] 1) In the presence of a solvent, alumina raw materials and calcium oxide raw materials are mixed and ground, and the ground products are dried and sieved;

[0051] 2) After the sieved product comes into contact with the release agent, it is then shaped and fired.

[0052] In the grinding process, the mixture is ground to D(50)≤30μm, and the sieving process allows the dried product to pass through a 10-25 mesh.

[0053] According to the present invention, in step 1), the alumina raw material may be selected from one or more of hydrated alumina, transition phase alumina, and α-alumina; preferably, the alumina raw material is hydrated alumina. The hydrated alumina is selected from one or more of α-gibbsite, boehmite, and gibbsite. For cost considerations, the hydrated alumina is preferably α-gibbsite.

[0054] According to the present invention, in step 1), the calcium oxide raw material may be selected from one or more of calcium hydroxide, calcium oxide and calcium carbonate; preferably, the calcium oxide raw material is calcium carbonate.

[0055] According to the present invention, the solvent is not particularly limited and can be any solvent commonly used in the preparation of calcium aluminate materials, as long as the calcium aluminate material can be obtained smoothly. For example, it can be one or more of water, ethanol, acetone and ethylene glycol; preferably, the solvent is water.

[0056] According to the present invention, for the purpose of controlling the crystal phase, the mass ratio of the solvent, alumina raw material and calcium oxide raw material can be 1:0.4-0.9:0.1-0.23; preferably, the mass ratio of the solvent, alumina raw material and calcium oxide raw material is 1:0.6-0.8:0.1-0.2.

[0057] According to the present invention, for the purpose of controlling the crystal phase, the amount of the alumina raw material can be 80-92% by weight of the calcium aluminate material; preferably, the amount of the alumina raw material is 82-90% by weight of the calcium aluminate material.

[0058] According to the present invention, for the purpose of controlling the crystal phase, the mixture is ground to D(50)≤20μm during the grinding process; preferably, the mixture is ground to D(50)≤15μm during the grinding process.

[0059] In this invention, during the grinding step after mixing the solvent, alumina raw material, and calcium oxide raw material, the grinding operation can be performed using a wet grinding mill commonly used in the art, without particular limitation, as long as it can grind to the specified range. Preferably, the grinding is performed using a colloid mill or a ball mill. When using a colloid mill, preferably, the grinding is performed until D(50) ≤ 15 μm.

[0060] According to the present invention, when performing the drying process, the drying conditions include: a temperature of 50-300°C and a time of 0.1-24h; preferably, the drying conditions include: a temperature of 60-150°C and a time of 1-8h.

[0061] In this invention, the drying can be carried out using existing drying technologies, such as oven drying, vacuum drying, rotary evaporation drying, spray drying, or vibratory fluidized bed drying, etc., without any particular limitation, but spray drying or rotary evaporation drying is preferred.

[0062] According to the present invention, when sieving the obtained dried product, the sieving can be performed using a sieving method commonly used in the art, without particular limitation, as long as all the dried product passes through the sieve. The sieving causes the dried product to pass through a 10-25 mesh sieve; preferably, the sieving causes the dried product to pass through a 10-20 mesh sieve.

[0063] Additionally, step 1) includes a step of crushing the dried product before sieving. The crushing method is not particularly demanding; simply pulverizing the dried product is sufficient. Furthermore, if any dried product fails to pass through the sieve, further crushing and sieving operations are performed to ensure that all the dried product passes through the sieve.

[0064] In this invention, in order to smoothly separate the molded product from the mold, the sieved product is brought into contact with and mixed with a release agent. The release agent is not particularly limited and can be one or more commonly used release agents in the art, such as starch, graphite, coke, stearic acid, and stearates; preferably, the release agent is one or more of stearates, graphite, and coke.

[0065] According to the present invention, step 2) may further include the step of adding a molding aid during the contact process. There is no particular limitation on the molding aid; it can be any of the molding aids commonly used in the art for preparing calcium aluminate materials. For example, the molding aid may be selected from one or more of water, nitric acid, ethanol, and ethylene glycol; preferably, the molding aid is water.

[0066] According to the present invention, the molding can be performed by sheet molding, extrusion molding or ball rolling; preferably, the molding is performed by sheet molding.

[0067] According to a particularly preferred embodiment of the present invention, the conditions for tableting by compression molding include: pressure of 10-60 kN, particle diameter of 2-20 mm, and thickness of 2-16 mm.

[0068] Next, the product obtained by molding is roasted.

[0069] According to the present invention, the calcination conditions include a temperature of 1200-1500°C and a time of 1-8 hours; preferably, the calcination conditions include a temperature of 1250-1450°C and a time of 2-6 hours. Furthermore, the calcination operation is carried out in an air atmosphere.

[0070] According to a third aspect of the present invention, a calcium aluminate material prepared by the method for preparing calcium aluminate according to the second aspect of the present invention is provided.

[0071] The present invention will be described in detail below through embodiments, but the present invention is not limited to the following embodiments.

[0072] X-ray diffractometer: Purchased from Rigaku, Japan, model SmartLab SE.

[0073] The X-ray diffraction method for determining the crystal phase composition is as follows: copper target, Kα rays, tube voltage of 40kV, tube current of 40mA, light source wavelength λ=0.15418nm, scanning rate of 5° / min, and scanning range of 10°-80°.

[0074] F50AB type colloid mill: purchased from Shenyang Xinxuguang Machinery Equipment Manufacturing Co., Ltd.

[0075] DECO-PBM-H-0.4L horizontal ball mill: purchased from Changsha DECO Instrument Equipment Co., Ltd.

[0076] Example 1

[0077] 1) Weigh 90g of α-gibbsite that has passed through 100 mesh and 18.0g of calcium carbonate powder that has passed through 100 mesh, add 150mL of water, mix thoroughly, and then inject into a colloid mill. Select the grinding degree as scale 2 and grind for 30min under this condition until D(50) is 10μm. The resulting slurry is collected in an enamel tray and dried in an oven at 80℃ for 6h. After that, it is crushed and passed through a 20-mesh sieve.

[0078] 2) Add 2.7g of graphite powder, mix thoroughly, and then compress into cylindrical tablets with a diameter of 5mm and a thickness of 2-4mm using a tablet press. The resulting tablet granules are heated from room temperature to 1330℃ in a muffle furnace within 9 hours and held at that temperature for 3 hours to finally obtain composite oxide A.

[0079] After crushing and grinding, the crystal phase composition of composite oxide A was determined. Analysis showed that the main crystal phases of composite oxide A were α-Al₂O₃ and calcium aluminate (CaAl₄O₇, denoted as CA₂). To characterize the crystal phase composition of this product, XRD diffraction patterns were used, where the ratio of the peak intensities of the characteristic diffraction peaks of CA₂ and α-Al₂O₃ at 25.4° and 57.5° (I₁, I₂, I₃) was used. 25.4° / I 57.5° The crystal phase composition ratio in the product was 3.20, and the results are shown in Table 1.

[0080] Example 2

[0081] 1) Weigh 117g of α-gibbsite that has passed through 100 mesh and 18.0g of calcium carbonate powder that has passed through 100 mesh. Add 150mL of water and mix thoroughly. Then, inject the mixture into a colloid mill and select the grinding degree as scale 2. Grind for 30min under these conditions until D(50) is 13μm. Collect the resulting slurry into an enamel tray and dry it in an oven at 80℃ for 7h. Then crush it and pass it through a 20-mesh sieve.

[0082] 2) Add 2.7g of graphite powder, mix thoroughly, and then compress into cylindrical tablets with a diameter of 5mm and a thickness of 2-4mm using a tablet press. The resulting tablet granules are heated from room temperature to 1330℃ in a muffle furnace within 10 hours and held at that temperature for 3 hours to finally obtain composite oxide B.

[0083] After crushing and grinding, the crystal phase composition of composite oxide B was determined. Analysis showed that the main crystal phases of composite oxide A were α-Al₂O₃ and calcium aluminate (CaAl₄O₇, denoted as CA₂). To characterize the crystal phase composition of this product, XRD diffraction patterns were used, where the ratio of the peak intensities of the characteristic diffraction peaks of CA₂ and α-Al₂O₃ at 25.4° and 57.5° (I₁, I₂, I₃) was used. 25.4° / I57.5° The crystal phase composition ratio in the product was 2.75, and the results are shown in Table 1.

[0084] Example 3

[0085] 1) Weigh 117g of α-gibbsite that has passed through 100 mesh and 18.0g of calcium carbonate powder that has passed through 100 mesh. Add 150mL of water and mix thoroughly. Then, inject the mixture into a colloid mill and select the grinding degree as scale 2. Grind for 1.0h under these conditions until D(50) is 11μm. Collect the resulting slurry into an enamel tray and dry it in an oven at 80℃ for 8h. Then crush it and pass it through a 20-mesh sieve.

[0086] 2) Add 2.7g of graphite powder, mix thoroughly, and then compress into cylindrical tablets with a diameter of 5mm and a thickness of 2-4mm using a tablet press. The resulting tablet granules are heated from room temperature to 1310℃ in a muffle furnace within 10 hours and held at that temperature for 4 hours to finally obtain composite oxide C.

[0087] After crushing and grinding, the crystal phase composition of composite oxide C was determined. Analysis showed that the main crystal phases of composite oxide A were α-Al₂O₃ and calcium dialuminate (CaAl₄O₇, denoted as CA₂). To characterize the crystal phase composition of this product, XRD diffraction patterns were used, where the ratio of the peak intensities of the characteristic diffraction peaks of CA₂ and α-Al₂O₃ at 25.4° and 57.5° (I₁, I₂, I₃) was used. 25.4° / I 57.5° The crystal phase composition ratio in the product was 3.50, and the results are shown in Table 1.

[0088] Example 4

[0089] 1) Weigh 120g of α-gibbsite that has passed through 100 mesh and 20.0g of calcium carbonate powder that has passed through 100 mesh. Add 166mL of water and mix thoroughly. Then, inject the mixture into a colloid mill and select the grinding degree as scale 2. Grind for 50min under these conditions until D(50) is 12.2μm. Collect the resulting slurry into an enamel tray and dry it in an oven at 80℃ for 7h. After that, crush it and pass it through a 20-mesh sieve.

[0090] 2) Add 3.8g of graphite powder, mix thoroughly, and then compress into cylindrical tablets with a diameter of 5mm and a thickness of 2-4mm using a tablet press. The resulting tablet granules are heated from room temperature to 1330℃ in a muffle furnace within 10 hours and held at that temperature for 4 hours to finally obtain composite oxide D.

[0091] After crushing and grinding, the crystal phase composition of composite oxide D was determined. Analysis showed that the main crystal phases of composite oxide A were α-Al₂O₃ and calcium dialuminate (CaAl₄O₇, denoted as CA₂). To characterize the crystal phase composition of this product, XRD diffraction patterns were used, where the ratio of the peak intensities of the characteristic diffraction peaks of CA₂ and α-Al₂O₃ at 25.4° and 57.5° (I₁, I₂, I₃) was used. 25.4° / I 57.5° The crystal phase composition ratio in the product was 3.35, and the results are shown in Table 1.

[0092] Example 5

[0093] 1) Weigh 120.0g of α-gibbsite that passes through 100 mesh and 36.0g of calcium carbonate powder that passes through 100 mesh. Add 190mL of water and mix thoroughly. Then, inject the mixture into a colloid mill and select the grinding degree as scale 2. Grind for 45min under these conditions until D(50) is 9μm. Collect the resulting slurry into an enamel tray and dry it in an oven at 80℃ for 7h. After that, crush it and pass it through a 20-mesh sieve.

[0094] 2) Add 4.2g of graphite powder, mix thoroughly, and then compress into cylindrical tablets with a diameter of 5mm and a thickness of 2-4mm using a tablet press. The resulting tablet granules are heated from room temperature to 1330℃ in a muffle furnace within 9 hours and held at that temperature for 4 hours to finally obtain composite oxide E.

[0095] After crushing and grinding, the crystal phase composition of composite oxide E was determined. Analysis showed that the main crystal phases of composite oxide E were calcium aluminate (CaAl4O7, denoted as CA2), calcium aluminate (CaAl2O4, denoted as CA), and α-Al2O3. To characterize the crystal phase composition of this product, XRD diffraction patterns were used, where the ratio of the peak intensities of the characteristic diffraction peaks of CA2 and α-Al2O3 at 25.4° and 57.5° (Ig) was used. 25.4° / I 57.5° The intensity of CA at 30.1° is 4.21, which is the ratio of the intensity of the characteristic diffraction peak at 30.1° to that at 57.5° of the α-Al₂O₃ crystal phase. 30.1° / I 57.5° The value was 0.20, and the results are shown in Table 1.

[0096] Example 6

[0097] 1) Weigh 90g of α-gibbsite that passes through 100 mesh and 18.0g of calcium carbonate powder that passes through 100 mesh, add 150mL of water, mix thoroughly, load into a ball mill jar, grind on a horizontal ball mill until D(50) is 9.9μm, collect the resulting slurry in an enamel tray, dry in an oven at 80℃ for 6h, then crush and pass through a 20-mesh sieve;

[0098] 2) Add 2.7g of graphite powder, mix thoroughly, and then compress into cylindrical tablets with a diameter of 5mm and a thickness of 2-4mm using a tablet press. The resulting tablet granules are heated from room temperature to 1330℃ in a muffle furnace within 9 hours and held at that temperature for 3 hours to finally obtain composite oxide F.

[0099] After crushing and grinding, the composite oxide F underwent crystalline phase composition determination. Analysis showed that the main crystalline phases of composite oxide F were α-Al₂O₃ and calcium aluminate (CaAl₄O₇, denoted as CA₂). To characterize the crystalline phase composition of this product, XRD diffraction patterns were used, where the ratio of the peak intensities of the characteristic diffraction peaks of CA₂ and α-Al₂O₃ at 25.4° and 57.5° (I₁, I₂, I₃) was used. 25.4° / I 57.5° The crystal phase composition ratio in the product was 2.92, and the results are shown in Table 1.

[0100] Comparative Example 1

[0101] 1) Weigh 90g of α-gibbsite (passed through 100 mesh) and 18.0g of calcium carbonate powder (passed through 100 mesh), and mix thoroughly;

[0102] 2) Add 2.7g of graphite powder, mix thoroughly, and then compress into cylindrical tablets with a diameter of 5mm and a thickness of 2-4mm using a tablet press. The resulting tablet granules are heated from room temperature to 1330℃ in a muffle furnace within 9 hours and held at that temperature for 4 hours to finally obtain composite oxide G.

[0103] After crushing and grinding, the composite oxide G underwent crystal phase composition determination. The XRD pattern of the obtained product is shown below. Figure 2 Analysis showed that the main crystalline phases of composite oxide G were α-Al₂O₃ and calcium aluminate (CaAl₄O₇, denoted as CA₂), with a small amount of calcium aluminate (CaAl₂O₄, denoted as CA). To characterize the crystalline phase composition of this product, XRD diffraction patterns were used, where the ratio of the characteristic diffraction peak intensities of the CA₂ crystal plane and the α-Al₂O₃ crystal plane at 25.4° and 57.5° was I. 25.4° / I 57.5° =1.31, the ratio of the intensity of the characteristic diffraction peak of the CA crystal plane at 30.1° to the intensity of the diffraction peak of the α-Al₂O₃ crystal phase at 57.5° (I 30.1° / I 57.5° The value is 0.27.

[0104] Comparative Example 2

[0105] 1) Weigh 90.0g of α-gibbsite that passes through 100 mesh and 36.0g of calcium carbonate powder that passes through 100 mesh. Add 150mL of water and mix thoroughly. Then, inject the mixture into a colloid mill and select the grinding degree as scale 2. Grind for 30min under these conditions until D(50) is 10μm. Collect the resulting slurry into an enamel tray and dry it in an oven at 80℃ for 6h. After that, crush it and pass it through a 50-mesh sieve.

[0106] 2) Add 2.7g of graphite powder, mix thoroughly, and then compress into cylindrical tablets with a diameter of 5mm and a thickness of 2-4mm using a tablet press. The resulting tablet granules are heated from room temperature to 1330℃ in a muffle furnace within 9 hours and held at that temperature for 3 hours to finally obtain composite oxide H.

[0107] After crushing and grinding, the composite oxide H underwent crystal phase composition determination. The XRD pattern of the obtained product is shown below. Figure 3 Analysis showed that the main crystalline phases of the composite oxide H were calcium aluminate (CaAl4O7, denoted as CA2), calcium aluminate (CaAl2O4, denoted as CA), and α-Al2O3. To characterize the crystalline phase composition of this product, XRD diffraction patterns were used, where the ratio of the peak intensities of the characteristic diffraction peaks of CA2 and α-Al2O3 at 25.4° and 57.5° (Ig) was used. 25.4° / I 57.5° The ratio of the intensity of the characteristic diffraction peak of CA at 30.1° to that of the diffraction peak of the α-Al₂O₃ phase at 57.5° is 2.72. 30.1° / I 57.5° The value was 1.76, and the results are shown in Table 1.

[0108] Comparative Example 3

[0109] 1) Weigh 90 g of α-gibbsite that passes through 100 mesh and 18 g of calcium carbonate powder that passes through 100 mesh. Add 150 mL of water and mix thoroughly. Then, use an injection-type colloid mill and select grinding degree 5. Grind for 30 min under these conditions until D(50) is 41 μm. Collect the resulting slurry in an enamel tray and dry it in an oven at 80 °C for 6 h. After that, crush it and pass it through a 20 mesh sieve.

[0110] 2) Add 2.7g of graphite powder, mix thoroughly, and then compress into cylindrical tablets with a diameter of 5mm and a thickness of 2-4mm using a tablet press. The resulting tablet granules are heated from room temperature to 1330℃ in a muffle furnace within 9 hours and held at that temperature for 3 hours to finally obtain composite oxide I.

[0111] After crushing and grinding, the crystal phase composition of composite oxide I was determined. Analysis showed that the main crystal phases of composite oxide I were α-Al₂O₃, calcium aluminate (CaAl₄O₇, denoted as CA₂), and a small amount of calcium aluminate (CaAl₂O₄, denoted as CA). To characterize the crystal phase composition of this product, XRD diffraction patterns were used, where the ratio of the characteristic diffraction peak intensities of CA₂ and α-Al₂O₃ at 25.4° and 57.5° (I₁, I₂, I₃) was used. 25.4° / I 57.5 ) ° The ratio of the intensity of the characteristic diffraction peak of CA at 30.1° to that of the diffraction peak of the α-Al₂O₃ phase at 57.5° is 1.13. 30.1° / I 57.5° The value is 0.16.

[0112] Test Example 1

[0113] The specific surface area, water absorption rate and lateral compressive strength of the composite oxide AH obtained in the examples and comparative examples were determined according to the following methods, and the results are also shown in Table 1.

[0114] The specific surface area was determined as follows: the sample was pre-degassed under vacuum at 200℃ for 3 hours to remove adsorbed moisture and impurity gases. Then, the N2 adsorption-desorption isotherm of the sample was measured using a Micromeritics ASAP2460 physical adsorption instrument, and the specific surface area of ​​the sample was calculated according to the BET equation.

[0115] The method for determining the water absorption rate is as follows: Weigh 2-5g of sample into a 50mL beaker, then add 50mL of deionized water to the beaker, place it on a digital display magnetic stirring hot plate, keep it at 70℃ for 30min, drain off the excess water, weigh the mass of the wet sample using a balance (recorded as m2), and calculate the water absorption rate of the carrier according to the following formula: Water absorption rate = (m2-m1) / m1×100%.

[0116] The method for determining lateral crush strength is as follows: Select 10 samples, measure the thickness of each sample (unit: mm), and then use a DLⅡ type intelligent particle strength meter to determine the lateral crush strength of the sample. Divide the obtained strength value by the thickness and take the average value.

[0117] The term "water absorption rate" as used in this invention refers to the weight percentage (in %) of a unit mass of carrier saturated with adsorbed water at room temperature.

[0118] Table 1

[0119]

[0120] Comparing the physical properties and crystal phase composition data of Examples 1-6 and Comparative Examples 1-3, it can be seen that the diffraction peak intensity I at 25.4° of the calcium aluminate material prepared by the preparation method of the present invention is... 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Satisfy I 25.4° / I 57.5° ≥1.5 and I 30.1° / I 57.5° When the value is ≤0.5, the lateral compressive strength, water absorption rate, and specific surface area are all improved, and the lateral compressive strength improvement rate is relatively high, which significantly improves the strength of the carrier.

[0121] Comparing Example 1 and Comparative Examples 1-3, without grinding or sieving, and when D(50) exceeds the scope of this invention, the diffraction peak intensity I of the calcium aluminate material at 25.4° is... 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Unable to satisfy I 25.4° / I 57.5° ≥1.5 and I 30.1° / I 57.5° If the value is ≤0.5, then the calcium aluminate material of the present invention cannot be obtained.

[0122] 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 calcium aluminate material, characterized in that, This calcium aluminate material comprises monocalcium dialuminate and α-Al₂O₃, with monocalcium dialuminate as the main crystalline phase. In powder XRD diffraction analysis, the diffraction peak intensity I of this calcium aluminate material at 25.4° is... 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Satisfying the following formulas (1) and (2), I 25.4° / I 57.5° ≥1.5 Formula (1), I 30.1° / I 57.5° ≤0.5 Formula (2); The preparation method of the calcium aluminate material includes the following steps: 1) In the presence of a solvent, alumina raw materials and calcium oxide raw materials are mixed and ground, and the ground products are dried and sieved; 2) After the sieved product comes into contact with the release agent, it is then shaped and fired. In the grinding process, the mixture is ground to D(50)≤30μm, and the sieving process allows the dried product to pass through a 20-mesh sieve.

2. The calcium aluminate material according to claim 1, wherein, In powder XRD diffraction analysis, the diffraction peak intensity I of the calcium aluminate material at 25.4° was... 25.4° The diffraction peak intensity I at 30.1° 30.1° The diffraction peak intensity I at 57.5° 57.5° Satisfy the following formulas (3) and (4), I 25.4° / I 57.5° ≥2.5 Formula (3), I 30.1° / I 57.5° ≤0.2 Formula (4).

3. The calcium aluminate material according to claim 1, wherein, The specific surface area of ​​the calcium aluminate material is 1-5 m². 2 / g.

4. The calcium aluminate material according to claim 3, wherein, The specific surface area of ​​the calcium aluminate material is 2-4 m². 2 / g.

5. The calcium aluminate material according to claim 4, wherein, The specific surface area of ​​the calcium aluminate material is 3-4 m². 2 / g.

6. The method for preparing the calcium aluminate material according to any one of claims 1-5, characterized in that, The method includes the following steps: 1) In the presence of a solvent, alumina raw materials and calcium oxide raw materials are mixed and ground, and the ground products are dried and sieved; 2) After the sieved product comes into contact with the release agent, it is then shaped and fired. In the grinding process, the mixture is ground to D(50)≤30μm, and the sieving process allows the dried product to pass through a 20-mesh sieve.

7. The method according to claim 6, wherein, The alumina raw material is selected from one or more of hydrated alumina, transition phase alumina, and α-alumina.

8. The method according to claim 7, wherein, The alumina raw material is hydrated alumina.

9. The method according to claim 8, wherein, The hydrated alumina is selected from one or more of α-gibbsite, diaspore, and boehmite.

10. The method according to claim 9, wherein, The hydrated alumina is α-gibbsite.

11. The method according to claim 6, wherein, The calcium oxide raw material is selected from one or more of calcium hydroxide, calcium oxide, and calcium carbonate.

12. The method according to claim 11, wherein, The calcium oxide raw material is calcium carbonate.

13. The method according to claim 6, wherein, The solvent is one or more of water, ethanol, acetone, and ethylene glycol.

14. The method according to claim 13, wherein, The solvent is water.

15. The method according to claim 6, wherein, The mass ratio of the solvent, alumina raw material and calcium oxide raw material is 1:0.4-0.9:0.1-0.

23.

16. The method according to claim 6, wherein, The amount of the alumina raw material is 80-92% by weight of the calcium aluminate material.

17. The method according to claim 16, wherein, The amount of the alumina raw material is 82-90% by weight of the calcium aluminate material.

18. The method according to claim 6, wherein, In the grinding process, the mixture is ground until D(50)≤20μm.

19. The method according to claim 18, wherein, In the grinding process, the mixture is ground until D(50)≤15μm.

20. The method according to claim 6, wherein, The drying conditions include a temperature of 50-300℃ and a time of 0.1-24h.

21. The method according to claim 20, wherein, The drying conditions include a temperature of 65-150℃ and a time of 1-8 hours.

22. The method according to claim 6, wherein, The mass ratio of the release agent to the calcium oxide raw material is 0.02-0.6:

1.

23. The method according to claim 22, wherein, The mass ratio of the release agent to the calcium oxide raw material is 0.05-0.5:

1.

24. The method according to claim 22, wherein, The release agent is selected from one or more of starch, graphite, coke, stearic acid, and stearate.

25. The method according to claim 24, wherein, The release agent is one or more of stearate, graphite, and coke.

26. The method of claim 25, wherein, A molding aid is added during the contact process.

27. The method according to claim 26, wherein, The molding aid is selected from one or more of water, nitric acid, ethanol, and ethylene glycol.

28. The method according to claim 26, wherein, The molding process employs sheet molding, extrusion molding, or ball rolling molding.

29. The method according to claim 28, wherein, The molding process is a sheet compression molding.

30. The method according to claim 6, wherein, The roasting conditions include a temperature of 1200-1500℃ and a time of 1-8 hours.

31. The method according to claim 30, wherein, The roasting conditions include a temperature of 1250-1450℃ and a time of 2-6 hours.

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