Calcium aluminate material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts and preparation thereof, and discloses a calcium aluminate material as well as a preparation method and application thereof, and the calcium aluminate material contains 5-30wt% of calcium oxide and 70-95wt% of aluminum oxide; the crystal phase composition of the calcium aluminate material meets the conditions that I25.4 degrees / I57.5 degrees is larger than or equal to 3, I34.1 degrees / I57.5 degrees is larger than or equal to 3, and I30.1 degrees / I57.5 degrees is smaller than or equal to 0.5. The calcium aluminate material has special crystalline phase composition and physical properties, main crystalline phases of the calcium aluminate material are calcium dialuminate (CA2) and calcium hexaluminate (CA6), the calcium aluminate material contains a small amount of alpha-Al2O3 and basically does not contain calcium aluminate (CA), and the calcium aluminate material can be used in the fields of base catalysis or basic catalyst carriers such as hydrocarbon catalytic conversion, heavy oil pyrolysis-gasification coupling hydrogen production, ester exchange reaction and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts and their preparation, and particularly relates to a calcium aluminate material, a preparation method thereof, and an application thereof. Background Art

[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. Generally, pure calcium aluminate refractory cement is prepared from industrial alumina powder and high-quality limestone in a certain proportion, crushed and ground finely, pressed into rough blanks, calcined at high temperature, and then broken and ground finely to form a cementitious material. Its main mineral components are calcium monoaluminate (CA 2 ), calcium aluminate (CA), calcium hexaaluminate (CA 6 ), and α-aluminum oxide (α-Al 2 O 3 ), etc. Since the content of Al 2 O 3 in calcium aluminate cement is high, and the contents of calcium and impurities are correspondingly reduced, the refractoriness of the material is above 1690°C. The refractory castable prepared with pure calcium aluminate refractory cement has good high-temperature performance, such as high refractoriness, good thermal shock stability, and good slag erosion resistance, and is suitable for the refractory linings and refractory furnace charges of high-temperature kilns and thermal equipment in the cement industry, chemical industry, and metallurgical industry. Compared with refractory bricks, the refractory castable prepared with it has the advantages of simple manufacturing process and convenient construction, is suitable for on-site construction of any part and any shape, and can also produce large prefabricated products to meet the use requirements.

[0003] The main chemical components of calcium aluminate are α-aluminum oxide and CaO. In the CaO-Al 2 O 3 binary system, there are five compounds: C 3 A, C 12 A 7 , CA, CA 2 , and CA 6 . Conventional synthetic calcium aluminate materials usually contain multiple crystal phases, and have relatively low specific surface area and strength. As reported in the literature (Yang Qing. Development of pure calcium aluminate special cement by sintering method [J]. Cement, 1992(9): 27-28), the synthetic calcium aluminate special cement contains about 73% of CA 2 , 27% of CA, and the specific surface area is about 0.6 m 2 / g. The literature (Li Youqi, Li Yawei, Jin Shengli, etc. Synthesis and microstructure research of calcium hexaaluminate materials [J]. Refractories, 2004, 38(5): 318-323) used active α-Al 2 O 3 and CaCO 3 to synthesize a calcium hexaaluminate with the main crystal phase of CA6 refractory materials. The literature (Li Youqi, Ke Changming, Li Nan. Synthesis and microstructure research of dicalcium aluminate with low expansion coefficient [J]. Materials Review, 2006, 20(F05): 470 - 472) reported that using reactive α - Al 2 O 3 and CaCO 3 , in the formulation, the content of CaO and Al 2 O 3 is in the stoichiometric ratio of CA 2 , that is, m(CaO):m(Al 2 O 3 ) is 27.45:100. The pure CA 2 material was synthesized by reaction sintering method. The literature (Zeng Chunyan, Yi Shuai, Liu Yangai, etc. Influence of CaO and γ - Al 2 O 3 ratio on the synthesis of plate - like hexaaluminate [J]. Refractories, 2011, 45(002): 85 - 88) reported that using CaO and γ - Al 2 O 3 , when at the theoretical ratio of CA 6 , nearly pure CA 6 material can be synthesized. While in the case of calcium - rich formulation, the synthesized product contains a small amount of calcium monoaluminate (CA 2 ). The literature (Chen Feng, Hong Yanruo, Sun Jialin, etc. Chemical synthesis of high - purity calcium aluminate powder [J]. Refractories, 2004, 38(4): 245 - 348) selected saturated Ca(OH) 2 solution and AlCl 3 solution as the initial raw materials. At room temperature, using the co - precipitation method, under the condition that the molar ratio of Al 3+ and Ca 2+ is about 2.2, first synthesize the precursor of calcium aluminate hydrated precipitate, and then through low - temperature calcination, prepare high - activity, high - purity calcium aluminate powder with CA as the main crystal phase and containing a small amount of CA 2 binary mixture.

[0004] As described above, as a special high-temperature resistant material, calcium aluminate materials have been widely used and attracted attention in the cement, ceramic, and metallurgical industries. In addition, they can also be used as basic catalysts and support materials (① Wang Sihan, Zhang Yujian. Research status of hydrogen production technology by steam reforming of natural gas [J]. Industrial Catalysis, 2016, 24(4): 26-30; ② Wang Rongbin. Catalytic cracking-gasification process of heavy oil with calcium aluminate [J]. Acta Petrolei Sinica (Petroleum Processing), 2021, 37(2): 384-390). As a catalyst support for the conversion of natural gas to syngas, calcium aluminate materials have been applied industrially (① Huang Zhongtao. Industrial Catalyst Handbook [M]. Chemical Industry Press, 2004, p676; ② Shen Wenjie. Industrial application of CN-20 type catalyst [J]. Natural Gas Chemical Industry, 2002, 27(1): 19-25).

[0005] For catalytic materials, the strength, specific surface area, and crystal phase composition of different materials have a great impact on their performance. Most of the calcium aluminate materials reported in the literature have a relatively small specific surface area (mostly less than 1 m 2 / g) and low strength. In addition, there are few reports on materials with CA 2 and CA 6 as the main crystal phases. How to synthesize calcium aluminate materials with higher strength, larger specific surface area, and CA 2 and / or CA 6 as the main crystal phases is the problem that this invention endeavors to solve. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of most calcium aluminate materials having a relatively small specific surface area and low strength in the prior art, and to provide a calcium aluminate material, its preparation method and application. This calcium aluminate material has a special crystal phase composition and physical properties, with its main crystal phases being calcium dialuminate (CA 2 ), calcium hexaaluminate (CA 6 ), containing a small amount of α-Al 2 O 3 , and basically not containing calcium monoaluminate (CA), and can be used in the fields of alkali catalysis or basic catalyst carriers such as hydrocarbon catalytic conversion, coupled hydrogen production by pyrolysis-gasification of heavy oil, and transesterification reaction.

[0007] To achieve the above purpose, the first aspect of this invention provides a calcium aluminate material, wherein the calcium oxide content in the calcium aluminate material is 5-30 wt%, and the alumina content is 70-95 wt%;

[0008] The crystal phase composition of the calcium aluminate material satisfies I 25.4° / I 57.5° ≥3, I 34.1° / I 57.5° ≥3, I 30.1° / I 57.5°≤0.5;

[0009] Among them, I 25.4° is the peak intensity of the characteristic diffraction peak of calcium aluminate material at 25.4° in the XRD diffraction spectrum, I 30.1° is the peak intensity of the characteristic diffraction peak of calcium aluminate material at 30.1° in the XRD diffraction spectrum, I 34.1° is the peak intensity of the characteristic diffraction peak of calcium aluminate material at 34.1° in the XRD diffraction spectrum, I 57.5° It is the peak intensity of the characteristic diffraction peak of calcium aluminate material at 57.5° in the XRD diffraction spectrum.

[0010] A second aspect of the present invention provides a method for preparing a calcium aluminate material, wherein the method comprises:

[0011] (1) mixing an aluminum oxide source, a calcium oxide source and a solvent to obtain a colloid, and drying the ground colloid;

[0012] (2) uniformly mixing the product of step (1) with a release agent, and performing molding and pre-baking;

[0013] (3) subjecting the pre-calcined product to hydrothermal treatment and calcination.

[0014] The third aspect of the present invention provides a calcium aluminate material obtained by the preparation method described in the second aspect.

[0015] The fourth aspect of the present invention provides an application of the calcium aluminate material described in the first aspect or the third aspect in the field of catalyst carriers.

[0016] Through the above technical solution, the beneficial effects obtained are as follows:

[0017] (1) The calcium aluminate material provided by the present invention has a special crystal phase composition and physical properties, and its main crystal phase is calcium aluminate (CA 2 ), calcium hexaaluminate (CA 6 ), containing a small amount of α-Al 2 O 3 , basically does not contain calcium aluminate (CA), and can be used in the fields of alkaline catalysis or alkaline catalyst carriers such as hydrocarbon catalytic conversion, heavy oil pyrolysis-gasification coupled hydrogen production, and ester exchange reaction;

[0018] (2) The preparation method of the calcium aluminate material provided by the present invention comprises mixing the raw materials and then grinding them sufficiently, pre-baking them, and then performing hydrothermal treatment and baking them. The preparation method is simple, the raw materials are easy to obtain, and the calcium aluminate material with a specific composition and structure is obtained. DETAILED DESCRIPTION

[0019] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0020] In the first aspect of the present invention, a calcium aluminate material is provided, wherein the calcium aluminate material contains 5-30 wt% of calcium oxide and 70-95 wt% of alumina.

[0021] The crystal phase composition of the calcium aluminate material satisfies I 25.4° / I 57.5° ≥3, I 34.1° / I 57.5° ≥3, I 30.1° / I 57.5° ≤0.5;

[0022] Wherein, I 25.4° is the peak intensity of the characteristic diffraction peak of the calcium aluminate material at 25.4° in the XRD diffraction pattern, I 30.1° is the peak intensity of the characteristic diffraction peak of the calcium aluminate material at 30.1° in the XRD diffraction pattern, I 34.1° is the peak intensity of the characteristic diffraction peak of the calcium aluminate material at 34.1° in the XRD diffraction pattern, I 57.5° is the peak intensity of the characteristic diffraction peak of the calcium aluminate material at 57.5° in the XRD diffraction pattern.

[0023] In the present invention, the main crystal phases of the calcium aluminate material are calcium dialuminate (CaAl 4 O 7 , denoted as CA 2 ) and calcium hexaaluminate (CaAl 12 O 19 , denoted as CA 6 ), contain a small amount of α-Al 2 O 3 , and basically do not contain calcium monoaluminate (CaAl 2 O 4 , denoted as CA). The calcium aluminate material has a large specific surface area, relatively high mechanical strength and high water absorption.

[0024] In the present invention, the crystal phase composition of the calcium aluminate material is analyzed by an XRD diffraction pattern. The XRD test conditions are: copper target, Kα ray, tube voltage 40 kV, tube current 40 mA, light source wavelength λ = 0.15418 nm, scanning rate 5° / min, scanning range 10°-80°.

[0025] In the present invention, in the XRD diffraction pattern of the calcium aluminate material, the ratio of the peak intensities I of the characteristic diffraction peaks at 25.4° and 57.5° 25.4° / I 57.5° represents the crystal phase content of CA 2 ; the ratio of the peak intensities I of the characteristic diffraction peaks at 34.1° and 57.5° 34.1° / I 57.5° represents the crystal phase content of CA 6 ; the ratio of the peak intensities I of the characteristic diffraction peaks at 30.1° and 57.5° 30.1° / I 57.5° represents the crystal phase content of CA.

[0026] According to the present invention, preferably, the crystal phase composition of the calcium aluminate material satisfies I 25.4° / I 57.5° ≥3.5, preferably I 25.4° / I 57.5° ≥4. In the present invention, the crystal phase composition of the calcium aluminate material satisfies I 25.4° / I 57.5° ≤20.

[0027] According to the present invention, preferably, the crystal phase composition of the calcium aluminate material satisfies I 34.1° / I 57.5° ≥6, preferably I 34.1° / I 57.5° ≥8. In the present invention, the crystal phase composition of the calcium aluminate material satisfies I 34.1° / I 57.5° ≤30.

[0028] According to the present invention, preferably, the crystal phase composition of the calcium aluminate material satisfies I 30.1° / I 57.5° ≤0.3, preferably I 30.1° / I 57.5° ≤0.15.

[0029] According to the present invention, preferably, the calcium oxide content is 6-25 wt%, preferably 8-22 wt%, and the alumina content is 75-94 wt%, more preferably 78-92 wt%.

[0030] According to the present invention, preferably, the specific surface area of the calcium aluminate material is 1-6 m 2 / g, such as 1 m 2 / g, 1.5 m 2 / g, 1.8 m 2 / g, 2 m 2 / g, 2.5 m 2 / g, 3 m 2 / g, 3.5 m 2 / g, 4 m2 / g, 4.5 m 2 / g, 5 m 2 / g, 5.5 m 2 / g, 6 m 2 / g, or in the range between any two of them, preferably 1.5 - 5 m 2 / g, more preferably 1.8 - 4 m 2 / g. In the present invention, the specific surface area of the calcium aluminate material is obtained by testing with the nitrogen isothermal adsorption - desorption curve method. The determination method is as follows: The sample is pre - degassed in vacuum at 200 °C for 3 h to remove the adsorbed moisture and impurity gases in the sample. Then, the N 2 adsorption - desorption isotherm of the sample is measured by an ASAP2460 physical adsorption instrument of Micromeritics company, and the specific surface area of the sample is calculated according to the BET equation.

[0031] According to the present invention, preferably, the side pressure strength of the calcium aluminate material is 45 - 100 N / mm, such as 45 N / mm, 50 N / mm, 55 N / mm, 60 N / mm, 65 N / mm, 70 N / mm, 75 N / mm, 80 N / mm, 85 N / mm, 90 N / mm, 95 N / mm, 100 N / mm, or in the range between any two of them, preferably 50 - 90 N / mm. In the present invention, the determination method of the side pressure strength of the calcium aluminate material is as follows: Select 20 samples, measure the thickness of each sample (unit: mm) one by one, then use a DLⅡ type intelligent particle strength instrument to measure the lateral crushing strength of the samples, divide the obtained strength value by the thickness, and take the average value.

[0032] According to the present invention, preferably, the water absorption rate of the calcium aluminate material is greater than or equal to 28%, such as 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, or in the range between any two of them, preferably 29 - 35%. The determination method of the water absorption rate of the calcium aluminate material is as follows: Weigh 2 - 5 g of the sample (the sample mass is denoted as m1) and put it into a 50 mL beaker, then add 50 mL of deionized water to the beaker, place it on a digital display magnetic stirring electro - thermal plate, keep it at a constant temperature of 70 °C for 30 min, drain the excess water, weigh the mass of the wet sample with a balance (denoted as m2), and calculate the water absorption rate of the carrier according to the following formula: Water absorption rate = (m2 - m1) / m1 × 100%.

[0033] In the present invention, preferably, the calcium aluminate material with the above - mentioned specific composition and structure has a large specific surface area, high water absorption rate, and high mechanical strength, and is suitable for being used as a carrier for preparing catalysts.

[0034] In the second aspect of the present invention, a preparation method of a calcium aluminate material is provided, wherein the method includes:

[0035] (1) Mix an alumina source, a calcium oxide source, and a solvent to obtain a colloid, and dry the ground colloid.

[0036] (2) Mix the product of step (1) with a mold release agent evenly, and carry out molding and pre-baking.

[0037] (3) Carry out hydrothermal treatment and baking on the pre-baked product.

[0038] In the present invention, the provided preparation method of the calcium aluminate material has easily obtainable raw materials and a simple preparation method. The colloid is ground and then mixed evenly with the mold release agent, and after molding, pre-baking and baking are carried out, improving the performance of the obtained calcium aluminate material.

[0039] According to the present invention, the type of the alumina source is not particularly limited, and it is a substance that obtains alumina after conventional roasting in the art. Preferably, it is selected from at least one of hydrated alumina, transitional alumina, and inert α-alumina, preferably hydrated alumina, and more preferably trihydrate alumina.

[0040] According to the present invention, preferably, the addition amount of the calcium oxide source is such that the mass percentage content of calcium oxide in the obtained calcium aluminate material is 5-30 wt%, preferably 6-25 wt%, and more preferably 8-22 wt%.

[0041] According to the present invention, preferably, the addition amount of the alumina source is such that the mass percentage content of alumina in the obtained calcium aluminate material is 70-95 wt%, preferably 75-94 wt%, and more preferably 78-92 wt%.

[0042] According to the present invention, the type of the calcium oxide source is not particularly limited, and it is a substance that obtains calcium oxide after conventional roasting in the art. Preferably, the calcium oxide source is selected from at least one of calcium hydroxide, calcium oxide, and calcium carbonate, and preferably calcium carbonate.

[0043] According to the present invention, the type of the solvent is not particularly limited, and it is a conventional organic and / or inorganic solvent in the art. The solvent is selected from at least one of water, ethanol, and acetone.

[0044] According to the present invention, the dosage of the solvent is not particularly limited, and it is only necessary to fully mix the calcium oxide source and the alumina source. Preferably, based on the alumina source, the mass ratio of the solvent to the alumina source is 1-4:1, such as 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, or the range between any two of them, and preferably 1.5-3:1.

[0045] According to the present invention, preferably, in step (1), the colloid is ground until the particle D50 in the colloid ≤ 30 μm, preferably D50 ≤ 20 μm, and more preferably D50 ≤ 10 μm.

[0046] In the present invention, in order to make the added components mix more uniformly, the added alumina source and calcium oxide source are optionally crushed and sieved, preferably passing through a 100-mesh sieve, to obtain raw materials with finer particle sizes. In the present invention, the term "mesh" has its conventional meaning in the art, referring to the number of holes on a sieve per square inch. For example, 200 mesh means there are 200 holes on a sieve per square inch.

[0047] In the present invention, the method of colloidal grinding is not particularly limited, and conventional grinding methods in the art can be adopted to grind the colloidal particles to meet the above requirements. After grinding, the particle size of the colloidal particles is more uniformly dispersed.

[0048] In the present invention, preferably, the drying conditions include: the drying temperature is 50 - 300 °C, preferably 60 - 200 °C, more preferably 60 - 150 °C; the drying time is 0 - 24 h, preferably 0 - 15 h, more preferably 1 - 8 h.

[0049] In the present invention, the drying method is not particularly limited, and those skilled in the art can choose conventional drying methods. Preferably, at least one of oven drying, vacuum drying, rotary evaporation drying, spray drying, and vibrated fluidized bed drying is adopted, and spray drying and / or rotary evaporation drying are preferably adopted.

[0050] In the present invention, it also includes optionally crushing and screening the dried product. Those skilled in the art can choose whether to perform crushing and screening according to needs, and the methods of crushing and screening are not particularly limited.

[0051] According to the present invention, the type of the mold release agent is not particularly limited and is a conventional mold release agent in the art. Preferably, the mold release agent is selected from at least one of starch, graphite, coke, stearic acid, and stearate, more preferably selected from at least one of stearate, graphite, and coke, and even more preferably graphite. The above mold release agent can be removed by subsequent calcination without affecting the composition of the final product.

[0052] According to the present invention, preferably, the mass ratio of the mold release agent to the colloid is 0.002 - 0.02:1, such as 0.002:1, 0.003:1, 0.005:1, 0.007:1, 0.01:1, 0.012:1, 0.015:1, 0.017:1, 0.02:1, or the range between any two of them, and preferably 0.003 - 0.015:1.

[0053] In the present invention, in step (1), a molding aid is optionally added to the ground colloid. The type of the molding aid is not particularly limited, and those skilled in the art can select conventional molding aids. The addition amount of the molding aid is adjusted adaptively according to the molding situation of the colloid. Preferably, the molding aid is selected from combustible compounds, preferably at least one selected from polyester fibers, polyethylene glycols, and carbon materials. The weight-average molecular weights of the polyester fibers and polyethylene glycols are not particularly limited, and those skilled in the art can select polyester fibers and / or polyethylene glycols that are helpful for the molding of the colloid.

[0054] In the present invention, unless otherwise specified, the term "optionally" means containing or not containing, adding or not adding, adopting or not adopting. Specifically, in step (1) of the present invention, a molding aid may be added or not added.

[0055] In the present invention, preferably, the molding conditions in step (2) are not particularly limited, and conventional molding methods in the art can be adopted. Preferably, the dried product is pressed into shape in a tablet press.

[0056] According to the present invention, preferably, the conditions for pre-calcination include: in an air atmosphere, the pre-calcination temperature is 1000 - 1400 °C, such as 1000 °C, 1050 °C, 1100 °C, 1150 °C, 1200 °C, 1250 °C, 1300 °C, 1350 °C, 1400 °C, or the range between any two of them, preferably 1100 - 1350 °C; the pre-calcination time is 2 - 6 h, 2 h, 3 h, 4 h, 5 h, 6 h, or the range between any two of them, preferably 2 - 4 h.

[0057] In the present invention, under the above conditions for pre-calcination, combined with hydrothermal treatment, the specific surface area and mechanical strength of the calcium aluminate material can be significantly improved.

[0058] According to the present invention, preferably, the conditions for hydrothermal treatment include: the hydrothermal temperature is 160 - 300 °C, such as 160 °C, 180 °C, 200 °C, 220 °C, 240 °C, 260 °C, 280 °C, 300 °C, or the range between any two of them, preferably 180 - 260 °C; the hydrothermal time is 6 - 40 h, such as 6 h, 9 h, 12 h, 15 h, 18 h, 20 h, 25 h, 30 h, 35 h, 40 h, or the range between any two of them, preferably 9 - 25 h.

[0059] In the present invention, preferably, the heating rate for hydrothermal treatment is 1 - 6 °C / min, such as 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, 5 °C / min, 6 °C / min, or the range between any two of them, preferably 1 - 4 °C / min.

[0060] In the present invention, the equipment for hydrothermal treatment is not particularly limited, and those skilled in the art can select conventional hydrothermal treatment equipment, preferably in a hydrothermal autoclave. In the present invention, preferably, after the hydrothermal treatment is completed, the hydrothermal autoclave is cooled (preferably to room temperature) and then opened. Adopting this preferred implementation method can avoid potential safety hazards during opening the autoclave due to the autogenous pressure inside the autoclave during hydrothermal treatment at high temperature.

[0061] According to a preferred implementation method of the present invention, the hydrothermal treatment is carried out in a hydrothermal autoclave. A certain amount of water is loaded into the hydrothermal autoclave, a stainless steel mesh is placed above the water surface, and the sample is placed on the mesh (the sample does not contact the water). The hydrothermal autoclave lid is tightened, and the hydrothermal treatment is carried out.

[0062] In the present invention, preferably, the product of hydrothermal treatment is calcined after drying. The drying conditions are not particularly limited. Preferably, the drying temperature is 50 - 300 °C, and the drying time is 2 - 12 h.

[0063] According to the present invention, preferably, the calcination conditions include: in an air atmosphere, the calcination temperature is 1250 - 1450 °C, preferably 1280 - 1350 °C; the calcination time is 2 - 6 h, preferably 3 - 5 h.

[0064] In the present invention, the pre-calcination and calcination equipment are not particularly limited. Preferably, the pre-calcination and calcination can be carried out in a muffle furnace and / or a high-temperature electric furnace.

[0065] The third aspect of the present invention provides a calcium aluminate material prepared by the preparation method described in the second aspect.

[0066] The fourth aspect of the present invention provides an application of the calcium aluminate material described in the first aspect or the third aspect in the field of catalyst carriers.

[0067] In the present invention, the calcium aluminate material has a specific crystal phase composition, a large specific surface area, high mechanical strength, and high water absorption rate, and is suitable for use as a carrier in the catalyst field.

[0068] According to the present invention, preferably, the application of the calcium aluminate material in the field of catalyst carriers for hydrocarbon catalytic conversion, heavy oil pyrolysis-gasification coupling for hydrogen production, and transesterification reaction. In the present invention, preferably, the hydrocarbon catalytic conversion includes steam catalytic conversion of natural gas, dry gas catalytic conversion of natural gas with carbon dioxide, partial oxidation conversion of natural gas, and co-conversion of steam and carbon dioxide.

[0069] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples, unless otherwise specified, the reagents used in the present invention are all commercially available.

[0070] Example 1

[0071] (1) Weigh 90 g of α - gibbsite passing through 100 - mesh sieve and 18.0 g of calcium carbonate powder passing through 100 - mesh sieve. Add 150 mL of water, mix well, then pour it into a colloid mill. Select the grinding degree as scale 2 and grind for 30 min under this condition until the D50 reaches 10 μm. The obtained slurry is put into an enamel tray and dried in an oven at 80 °C for 6 h. Then, it is crushed and all passes through a 20 - mesh sieve.

[0072] (2) Add 2.7 g of graphite powder to the product of step (1), mix well, and then use a tablet press to press it into a cylindrical tablet with a diameter of 5 mm and a thickness of 2 - 4 mm. The obtained cylindrical tablet is heated from room temperature to 1100 °C in a muffle furnace within 9 h, held at this temperature for 3 h, and then cooled naturally.

[0073] (3) Load about 25% of the volume of distilled water into a hydrothermal autoclave lined with polytetrafluoroethylene material. Place a stainless - steel mesh 1 cm above the water surface, put the cylindrical tablet on the mesh, cover and tighten the autoclave lid. Slowly heat it to 180 °C within 2 h, hold for 24 h, and then cool naturally. Take out the sample and dry it in an oven at 80 °C for 5 h. Then heat it to 1330 °C within 9 h, hold for 4 h, and cool naturally to obtain calcium aluminate material A.

[0074] Example 2

[0075] (1) Weigh 92 g of Bayerite passing through 100 - mesh sieve, 17.0 g of calcium carbonate powder passing through 100 - mesh sieve, and mix them well with 100 g of water. Ball - mill in a ball mill until the D50 reaches 9.5 μm. The obtained slurry is put into an enamel tray and dried overnight in an oven at 80 °C. Then, it is crushed and all passes through a 20 - mesh sieve.

[0076] (2) Add 2.6 g of graphite powder to the product of step (1), mix well; use a tablet press to press it into a cylindrical tablet with a diameter of 5 mm and a thickness of 2 - 4 mm; the obtained cylindrical tablet particles are heated from room temperature to 1300 °C in a muffle furnace within 9 h, held at this temperature for 3 h, and then cooled naturally.

[0077] (3) Load about 20% of the volume of distilled water into a hydrothermal autoclave lined with polytetrafluoroethylene material. Place a stainless - steel mesh at a certain distance above the water surface, put the cylindrical tablet on the mesh, tighten the autoclave lid, slowly heat it to 200 °C within 2 h, hold for 12 h, and then cool naturally. Take out the sample and dry it in an oven at 80 °C for 6 h. After drying, the sample is heated to 1330 °C in a high - temperature electric furnace within 9 h, held for 4 h, and then cooled naturally to obtain calcium aluminate material B.

[0078] Example 3

[0079] (1) Weigh 91 g of α - gibbsite passing through 100 - mesh sieve and 18.3 g of calcium carbonate powder passing through 100 - mesh sieve, add 100 g of water, mix well, and ball - mill in a ball mill until the D50 is ground to 8.6 μm. The obtained slurry is put into an enamel tray and dried overnight at 80 °C in an oven. Then it is crushed and all passed through a 20 - mesh sieve.

[0080] (2) Add 0.8 g of calcium stearate to the product of step (1), mix well, and press it into a cylindrical tablet with a diameter of 5 mm and a thickness of 2 - 4 mm using a tablet press. The obtained tablet particles are heated from room temperature to 1200 °C in a muffle furnace within 9 h, held for 3 h, and then cooled naturally.

[0081] (3) Load about 25% of the volume of distilled water into a hydrothermal autoclave lined with polytetrafluoroethylene material. Place a stainless - steel mesh above the water surface, place the cylindrical tablet on the mesh (the sample does not contact the water), tighten the autoclave lid, heat it to 250 °C within 2 h, hold for 10 h, and then cool naturally. Take out the sample and dry it overnight at 80 °C in an oven. After drying, the sample is heated to 1330 °C in a high - temperature electric furnace within 9 h, held for 4 h, and then cooled naturally to obtain calcium aluminate material C.

[0082] Example 4

[0083] Prepare calcium aluminate material according to the method of Example 3, except that in step (2), it is pressed into a cylindrical tablet with a diameter of 5 mm and a thickness of 2 - 4 mm using a tablet press. The obtained cylindrical tablet is heated from room temperature to 1300 °C in a muffle furnace within 9 h, held for 3 h, and then cooled naturally.

[0084] (3) Load about 25% of the volume of distilled water into a hydrothermal autoclave lined with polytetrafluoroethylene material. Place a stainless - steel mesh above the water, place the sample obtained in step (2) on the mesh, tighten the autoclave lid, slowly heat it to 200 °C within 2 h, hold for 24 h, and then cool naturally. Take out the sample, dry it overnight at 80 °C in an oven, and then heat it to 1300 °C within 9 h, hold for 4 h, and cool naturally to obtain calcium aluminate material D.

[0085] Example 5

[0086] Prepare calcium aluminate material according to the method of Example 3, except that the pre - roasting temperature in step (2) is 1050 °C and the pre - roasting time is 2 h, and other conditions are the same as in Example 3 to obtain calcium aluminate material E.

[0087] Comparative Example 1

[0088] (1) Weigh 90 g of α - gibbsite passing through 100 - mesh sieve and 18.0 g of calcium carbonate powder passing through 100 - mesh sieve, and mix well;

[0089] (2) Add 2.7 g of graphite powder, mix well, and then use a tablet press to press into a cylindrical tablet with a diameter of 5 mm and a thickness of 2 - 4 mm. The obtained tablet particles are heated from room temperature to 1330 °C in a muffle furnace within 9 h and kept warm for 4 h to finally obtain the calcium aluminate material DB1.

[0090] Comparative Example 2

[0091] Weigh 92 g of α - gibbsite passing through 100 - mesh sieve, 17.0 g of calcium carbonate powder passing through 100 - mesh sieve, and then add 2.6 g of graphite powder. Mix well and use a tablet press to press into a cylindrical tablet with a diameter of 5 mm and a thickness of 2 - 4 mm. The obtained cylindrical tablet is heated from room temperature to 1330 °C in a muffle furnace within 9 h and kept warm for 4 h to finally obtain the carrier DB2.

[0092] Comparative Example 3

[0093] Weigh 91 g of α - gibbsite passing through 100 - mesh sieve, 18.3 g of calcium carbonate powder passing through 100 - mesh sieve, and then add 0.8 g of calcium stearate. Mix well and use a tablet press to press into a cylindrical tablet with a diameter of 5 mm and a thickness of 2 - 4 mm. The obtained tablet particles are heated from room temperature to 1330 °C in a muffle furnace within 9 h and kept warm for 4 h to finally obtain DB3.

[0094] Comparative Example 4

[0095] Prepare the calcium aluminate material according to the method of Example 3, with the difference that after forming in step (2), pre - calcination is not carried out, and directly hydrothermal treatment and calcination are carried out. The hydrothermal treatment and calcination conditions are the same as those in Example 3 to obtain the carrier DB4.

[0096] Test Example

[0097] Test the side - pressure strength, water absorption rate, specific surface area, and crystal phase composition of the prepared calcium aluminate material. The results are shown in Table 1.

[0098] Table 1

[0099]

[0100]

[0101] It can be seen from the results in Table 1 that the main crystal phase compositions of the calcium aluminate materials prepared by the method of the present invention are calcium dialuminate and calcium hexaaluminate, with higher side - pressure strength and higher water absorption rate. The main crystal phase compositions of the calcium aluminate material in Comparative Example 1 are calcium monoaluminate, α - Al 2 O 3 , calcium monohexaaluminate, and a small amount of calcium aluminate. The main crystal phase compositions of the calcium aluminate material in Comparative Example 2 are calcium monoaluminate and α - Al 2 O 3, the main crystal phase composition of the calcium aluminate material in Comparative Example 3 is calcium monoaluminate and α-Al 2 O 3 , the content of the calcium monoaluminate crystal phase in the calcium aluminate materials of Comparative Examples 1-3 is high, the side pressure strength is relatively low, and the water absorption rate is also relatively low.

[0102] 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 technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A calcium aluminate material, characterized in that, the calcium aluminate material contains 5 - 30 wt% of calcium oxide and 70 - 95 wt% of aluminum oxide; The crystal phase composition of the calcium aluminate material satisfies I 25.4° / I 57.5° ≥3, I 34.1° / I 57.5° ≥3, I 30.1° / I 57.5° ≤0.5; Among them, I 25.4° is the peak intensity of the characteristic diffraction peak of the calcium aluminate material at 25.4° in the XRD diffraction pattern, I 30.1° is the peak intensity of the characteristic diffraction peak of the calcium aluminate material at 30.1° in the XRD diffraction pattern, I 34.1° is the peak intensity of the characteristic diffraction peak of the calcium aluminate material at 34.1° in the XRD diffraction pattern, I 57.5° is the peak intensity of the characteristic diffraction peak of the calcium aluminate material at 57.5° in the XRD diffraction pattern.

2. The calcium aluminate material according to claim 1, wherein, The crystal phase composition of the calcium aluminate material satisfies I 25.4° / I 57.5° ≥ 3.5, preferably I 25.4° / I 57.5° ≥ 4; Preferably, the crystal phase composition of the calcium aluminate material satisfies I 34.1° / I 57.5° ≥ 6, preferably I 34.1° / I 57.5° ≥ 8; Preferably, the crystal phase composition of the calcium aluminate material satisfies I 30.1° / I 57.5° ≤ 0.3, preferably I 30.1° / I 57.5° ≤ 0.

15.

3. The calcium aluminate material according to claim 1 or 2, wherein, the calcium oxide content is 6 - 25 wt%, preferably 8 - 22 wt%, and the aluminum oxide content is 75 - 94 wt%, more preferably 78 - 92 wt%; Preferably, the specific surface area of the calcium aluminate material is 1-6 m 2 / g, preferably 1.5-5 m 2 / g, more preferably 1.8-4 m 2 / g; Preferably, the side compressive strength of the calcium aluminate material is 45 - 100 N / mm, preferably 50 - 90 N / mm; Preferably, the water absorption rate of the calcium aluminate material is greater than or equal to 28%, preferably 29 - 35%.

4. A preparation method of a calcium aluminate material, characterized in that, the method includes: (1) Mixing an aluminum oxide source, a calcium oxide source and a solvent to obtain a colloid, and drying the ground colloid; (2) Mixing the product of step (1) with a release agent evenly, and performing molding and pre - calcination; (3) Performing hydrothermal treatment and calcination on the pre - calcined product.

5. The preparation method according to claim 4, wherein, the aluminum oxide source is selected from at least one of hydrated aluminum oxide, transition phase aluminum oxide and inert α - aluminum oxide, preferably hydrated aluminum oxide; Preferably, the calcium oxide source is selected from at least one of calcium hydroxide, calcium oxide and calcium carbonate, preferably calcium carbonate; Preferably, the addition amount of the calcium oxide source is such that the mass percentage of calcium oxide in the prepared calcium aluminate material is 5 - 30 wt%, preferably 6 - 25 wt%, more preferably 8 - 22 wt%; Preferably, the addition amount of the aluminum oxide source is such that the mass percentage of aluminum oxide in the prepared calcium aluminate material is 70 - 95 wt%, preferably 75 - 94 wt%, more preferably 78 - 92 wt%.

6. The preparation method according to claim 4 or 5, wherein, the solvent is selected from at least one of water, ethanol and acetone; Preferably, the addition amount of the aluminum oxide source is based on aluminum oxide, and the mass ratio of the solvent to the aluminum oxide source is 1 - 4:1, preferably 1.5 - 3:1; Preferably, in step (1), the colloid is ground until the particle D50 in the colloid ≤ 30 μm, preferably D50 ≤ 20 μm, more preferably D50 ≤ 10 μm.

7. The preparation method according to any one of claims 4 - 6, wherein, the release agent is selected from at least one of starch, graphite, coke, stearic acid and stearate, preferably at least one of stearate, graphite and coke, more preferably graphite; Preferably, the mass ratio of the release agent to the colloid is 0.002 - 0.02:1, preferably 0.003 - 0.015:1; Preferably, the conditions of the pre - calcination include: in an air atmosphere, the pre - calcination temperature is 1000 - 1400 °C, preferably 1100 - 1350 °C; the pre - calcination time is 2 - 6 h, preferably 2 - 4 h.

8. The preparation method according to any one of claims 4 - 7, wherein, The conditions of the hydrothermal treatment include: the hydrothermal temperature is 160 - 300 °C, preferably 180 - 260 °C; the hydrothermal time is 6 - 40 h, preferably 9 - 25 h; Preferably, the calcination conditions include: in an air atmosphere, the calcination temperature is 1250 - 1450 °C, preferably 1280 - 1350 °C; the calcination time is 2 - 6 h, preferably 3 - 5 h.

9. The calcium aluminate material prepared by the preparation method according to any one of claims 4 - 8.

10. The application of the calcium aluminate material according to any one of claims 1 - 3, 9 in the field of catalyst carriers; Preferably, the application of the calcium aluminate material in the field of catalyst carriers for hydrocarbon catalytic conversion, heavy oil pyrolysis-gasification coupled hydrogen production or transesterification reaction.

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