Amorphous silicon-aluminum microsphere carrier material and preparation method thereof

Abstract

The invention discloses an amorphous silicon-aluminum microsphere carrier material and a preparation method thereof, and the amorphous silicon-aluminum microsphere carrier material comprises 50-80 wt.% of silicon dioxide and 15-40 wt.% of aluminum oxide based on the dry basis weight of the amorphous silicon-aluminum microsphere carrier material. The amorphous silicon-aluminum microsphere carrier material provided by the invention has a relatively high specific surface area and abundant large-size mesoporous channels, and is beneficial to improving the loading capacity of active components, improving the mass transfer and diffusion efficiency and reducing the diffusion limitation. The amorphous silicon-aluminum microsphere carrier material with a large specific surface area and abundant large-size mesoporous channels is prepared by changing crystal nucleation and growth modes of a product in the synthesis process, and meanwhile, the contents of silicon oxide and aluminum oxide can be flexibly regulated and controlled, so that different requirements of catalytic reactions in different fields can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical engineering, and particularly relates to an amorphous silica-alumina microsphere carrier material and a preparation method thereof. Background Art

[0002] Amorphous silica-alumina materials are composed of silicon oxide species and aluminum oxide species. Silicon atoms and aluminum atoms are interconnected through bridging oxygen bonds to form an amorphous framework, which has a rich pore structure, good thermal stability, and adjustable chemical composition. The charge density difference between silicon and aluminum atoms in amorphous silica-alumina materials endows them with both Bronsted acid (B acid) and Lewis acid (L acid) properties. While providing catalytic reaction active centers, they can also act as carriers to disperse and stabilize metal species, and are widely used in petroleum catalytic cracking, hydrocracking, and the anthraquinone process for hydrogen peroxide production. For large-sized reactant molecules in these reactions, amorphous silica-alumina materials are required to have a high specific surface area and suitable large-sized mesopores to reduce diffusion limitations during the reaction process, thereby increasing the reaction rate, reducing the occurrence of side reactions, and improving the yield of target products.

[0003] The synthesis methods of amorphous silica-alumina materials include physical mixing method, impregnation method, and precipitation method. The physical mixing method is to directly mix silica gel and aluminum gel to form a silica-alumina gel, and then obtain the product through subsequent drying, shaping, and calcination. CN117920167A discloses a method for preparing silica-alumina microspheres by the mixing method. An amorphous silicon-based raw material and clay are crushed and then mixed with a binder and water, and then spray-dried and shaped to obtain an amorphous silica-alumina microsphere material with a specific surface area of 40 - 65 m 2 / g and a pore volume of 0.08 - 0.12 cm 3 / g. Although the physical mixing method is simple to operate, the silicon and aluminum atoms are not atomically dispersed, resulting in poor uniformity. The impregnation method usually uses silica hydrogel or amorphous silica as the carrier, impregnates the aluminum salt solution on the carrier, and then undergoes washing, drying, and calcination. This method is also simple to operate, but the obtained silica-alumina material only forms acidic sites at the interface between silica and alumina.

[0004] The precipitation method is to directly react a silicon salt solution and an aluminum salt solution to generate a silica-alumina hydrogel, or first generate one gel and then precipitate another gel on this gel to obtain a silica-alumina hydrogel. The precipitation method can regulate the surface acidity and pore structure of the silica-alumina gel by changing the synthesis conditions, so it is more widely used. During the synthesis of amorphous silica-alumina materials by the precipitation method, due to different raw material mixing times and different degrees of crystal nucleation and growth, the primary particle sizes vary greatly, resulting in a relatively low specific surface area and small pore diameter of the final product. Therefore, synthesizing amorphous silica-alumina carriers with a high specific surface area and large pore diameter is a research direction with great application value.

[0005] CN104549540B discloses a preparation method of a macroporous amorphous silica-alumina support. First, an acidic aluminum salt solution is reacted with a sodium aluminate solution to prepare an aluminum sol, and then a sodium silicate solution is added. After ultrasonic aging, filtration, washing, drying, and calcination, a macroporous amorphous silica-alumina support is obtained, with a specific surface area of 268 - 386 m 2 / g, a pore volume of 0.6 - 1.16 cm 3 / g, and an average pore diameter of 4 - 10 nm. However, limited by the pore size of the support, this material is only applicable to reaction processes with relatively small kinetic diameters of reactant molecules.

[0006] CN103861659B discloses a synthesis method of a spherical silica-alumina support obtained by a one-step reaction of sodium aluminate, aluminum sulfate, and sodium silicate solutions. This method uses the sol-gel ability of sodium alginate to disperse and stabilize the filter cake material to prepare a silica-alumina spherical support, with a specific surface area of 200 - 450 m 2 / g, a pore volume of 0.6 - 1.5 cm 3 / g, and an average pore diameter of 6 - 25 nm. This method can obtain a support material with a relatively large pore diameter, but it requires the dispersion effect of sodium alginate to form a stable dispersion system in water, which also increases the exhaust gas emissions during the calcination process.

[0007] CN102949987B discloses an acidic silica-alumina material. First, an aluminum source and an alkali solution are reacted to form a gel, then a silicon source is added in proportion and aged for a certain time, and then ammonium exchange and fluosilicic acid treatment are carried out to obtain the acidic silica-alumina material, with a specific surface area of 250 - 350 m 2 / g, a pore volume of 0.7 - 0.9 cm 3 / g, and an average pore diameter of 8 - 15 nm. This material exhibits good light diesel cracking activity, but the synthesis steps are cumbersome, increasing the commercial production cost.

[0008] CN113830775A discloses a silica-alumina material. An alkaline silicon source is added to an acidic aluminum source, and then an alkali solution is added to adjust the pH value to 8.0 - 10.5. After aging, ammonium exchange is carried out to obtain the product, with a specific surface area of 150 - 600 m 2 / g, a pore volume of 0.5 - 1.5 cm 3 / g, and the pores with a pore diameter greater than 10 nm account for 70% - 98% of the total pore volume. In addition, CN118267982A discloses a silica-alumina-based support. Pseudoboehmite is used to prepare an aluminum sol, and tetraethyl orthosilicate is used to prepare a silicon sol. After mixing the silica-alumina sols, boric acid and urea are used for modification in sequence to obtain an amorphous silica-alumina support, with a specific surface area of 371 - 442 m 2 / g, a pore volume of 1.22 - 1.56 cm 3 / g, and the average pore diameter is 11.4 - 13.6 nm. The above research provides a technical solution for preparing an amorphous silica-alumina support with a high specific surface area and large pores, but it is necessary to add a pore-forming agent to achieve a rich pore structure and a binder to improve the wear resistance of the material. Summary of the Invention

[0009] Aiming at the deficiencies of the prior art, the present invention provides an amorphous silica-alumina microsphere support material and a preparation method thereof. By changing the crystal nucleation and growth mode of the product during the synthesis process, the present invention prepares an amorphous silica-alumina microsphere support material with a large specific surface area and rich large-size mesoporous channels. At the same time, the contents of silica and alumina can be flexibly adjusted to meet the different requirements of catalytic reactions in different fields.

[0010] In the first aspect of the present invention, an amorphous silica-alumina microsphere support material is provided. Based on the dry weight of the amorphous silica-alumina microsphere support material, the silica content is 50 - 80 wt.%, and the alumina mass percentage content is 15 - 40 wt.%.

[0011] The specific surface area of the amorphous silica-alumina microsphere support material is 200 - 400 m 2 / g, the mesoporous pore volume is 0.80 - 1.45 cm 3 / g, the average pore diameter is 15 - 50 nm, and the mass ratio of silica to alumina is (1.5 - 4.8):1.

[0012] Preferably, the specific surface area is 300 - 400 m 2 / g, the mesoporous pore volume is 1.00 - 1.40 cm 3 / g, and the average pore diameter is 20 - 45 nm.

[0013] Preferably, the particle size range of the amorphous silica-alumina microsphere support material is 40 - 250 μm.

[0014] In the second aspect of the present invention, a preparation method of an amorphous silica-alumina microsphere support material is provided, including the following steps: (1) Add an alkali to an aqueous solution of a silicon source and stir evenly to obtain a silicon-containing solution; (2) Add an inorganic acid to an aqueous solution of an aluminum source and stir evenly to obtain an aluminum-containing solution; (3) Slowly drop the aluminum-containing solution obtained in step (2) into the silicon-containing solution obtained in step (1) for reaction. After the feeding is completed, age for a certain time at a certain pH and temperature; (4) Filter and wash the material obtained in step (3) to obtain a filter cake; (5) Disperse the filter cake obtained in step (4) in water to make a slurry; (6) Spray-dry and calcine the slurry obtained in step (5) to obtain the finished product.

[0015] In the step (1), the silicon source is one or a combination of sodium silicate and water glass. Preferably, the modulus M of the water glass is 1.5 - 3.0. The concentration of the aqueous solution of the silicon source is 3 wt.% - 10 wt.% (calculated as silicon dioxide).

[0016] In the step (1), the base is sodium hydroxide or potassium hydroxide.

[0017] In the step (1), the stirring temperature is 20 - 60 °C, preferably 20 - 40 °C.

[0018] In the step (2), the aluminum source is one of aluminum sulfate, aluminum nitrate, and aluminum chloride. The concentration of the aqueous solution of the aluminum source is 2 wt.% - 10 wt.% (calculated as aluminum oxide).

[0019] In the step (2), the inorganic acid is one of concentrated sulfuric acid, concentrated nitric acid, and concentrated hydrochloric acid, and the addition amount is controlled to make the aging pH a specific value.

[0020] In the step (3), the atomic ratio of silicon atoms in the silicon source to aluminum atoms in the aluminum source is (3 - 6):1.

[0021] The aging pH in the step (3) is regulated by controlling the addition amount of the base in the step (1) and the addition amount of the inorganic acid in the step (2). In the step (3), the aging pH is controlled at 7 - 9, preferably 8 - 9.

[0022] In the step (3), the aging temperature is 40 - 80 °C, preferably 60 - 80 °C; the aging time is 2 - 8 h, preferably 4 - 6 h.

[0023] In the step (4), the material is filtered and washed in a centrifuge, and the impurity ions are removed by water washing to obtain a filter cake.

[0024] In the step (5), the solid content in the gel obtained after the filter cake is slurried is 5 - 15%, preferably 10 - 15%.

[0025] In the step (6), the calcination temperature is 550 - 750 °C, the calcination time is 4 - 8 h, preferably 6 h.

[0026] Advantages of the present invention: (1) In the present invention, an amorphous silicon-aluminum material is obtained by a one-step reaction of a silicon source and an aluminum source. By changing the reaction conditions and regulating the reaction process, the purpose of controlling the crystal nucleus growth rate is achieved, and amorphous silicon-aluminum gel particles with uniform particle size are obtained. Subsequently, microsphere carriers are prepared by spray drying forming, without adding a binder, and a specific surface area of 200 - 400 m 2 / g and a mesoporous pore volume of 0.80 - 1.45 cm 3a silicon-aluminum microsphere carrier with a specific surface area of 200 - 500 m² / g, an average pore diameter of 15 - 50 nm, a mass ratio of silicon dioxide to aluminum oxide of (1.5 - 4.8):1, and a particle size range of 40 - 250 μm; (2) The amorphous silicon-aluminum microsphere carrier material provided by the present invention has a relatively high specific surface area and abundant large-sized mesoporous channels. The relatively high specific surface area is beneficial to increasing the loading amount of active components, and the large-sized mesoporous channels are beneficial to improving the mass transfer and diffusion efficiency and reducing the diffusion limitation during the reaction process. Only inexpensive inorganic salts of silicon and aluminum are used as raw materials during the synthesis process. The synthesis process is simple, without the need to add pore-forming agents and binders, which can effectively reduce the preparation cost and has good industrial application potential. Description of the Drawings

[0027] Figure 1 is the scanning electron microscope of the silicon-aluminum microsphere material prepared in Example 3 of the present invention; Figure 2 is the particle size distribution of the silicon-aluminum microsphere material prepared in Example 3 of the present invention; Figure 3 is the adsorption-desorption isotherm and pore size distribution of the silicon-aluminum microsphere material prepared in Example 10 of the present invention; Figure 4 is the adsorption-desorption isotherm and pore size distribution of the silicon-aluminum microsphere material prepared in Comparative Example 1 of the present invention; Figure 5 is the scanning electron microscope of the silicon-aluminum microsphere material prepared in Comparative Example 1 of the present invention. Detailed Embodiments

[0028] The following further illustrates the present invention in conjunction with embodiments. The present invention is not limited to the embodiments. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of each raw material of the products of the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

[0029] Particle size distribution: According to the principle of "GB / T 21779-2008, Light Scattering Test Method for Particle Size Distribution of Metal Powders and Related Compounds", the particle size of the sample was tested using a Mastersizer 2000 type laser particle size analyzer produced by Malvern Instruments Limited, UK.

[0030] Pore structure: The nitrogen adsorption-desorption isotherm of the sample was measured using an ASAP 2460 type analyzer produced by Micromeritics, USA. Before the test, it was degassed at 300 °C for 6 h, and the specific surface area, pore volume, and pore size distribution of the carrier were obtained by the BET method, the single-point method, and the BJH method.

[0031] Elemental composition: The elemental composition of the material was tested using an S8 tiger type X-ray fluorescence spectrometer produced by Bruke.

[0032] Wear index: Weigh 20.0 g of the sample with a particle size of 45 - 150 μm, add it to 20.0 mL of deionized water and disperse evenly, then transfer it to the sample bucket of the wear index tester. Use nitrogen as the gas source to blow for 30 min, then collect the slurry. After separating the solid, dry it at 120 °C to constant weight, measure the mass less than 20 μm, denoted as X, and the mass greater than 20 μm, denoted as Y. Then the wear index of this sample is X / (X + Y).

[0033] Scanning electron microscope test: Use the high-resolution field emission scanning electron microscope SU8010 of Hitachi, Japan to observe the surface morphology of the sample.

[0034] Example 1

[0035] Weigh 300 g of Na2SiO3·5H2O, add it to 728 g of deionized water, and then add 26 g of solid sodium hydroxide. Stir and dissolve at 40 °C. At the same time, weigh 310 g of Al2(SO4)3·18H2O, add it to 480 g of deionized water, and stir and dissolve at 40 °C. Subsequently, under stirring at 600 r / min, slowly drip the aluminum sulfate solution into the sodium silicate solution. After the addition is completed, raise the temperature to 60 °C and age for 4 h, and the aging pH is 8.75. After aging, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 210 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 550 °C for 4 h to obtain an amorphous silica-alumina microsphere carrier material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0036] Example 2

[0037] Weigh 300 g of Na2SiO3·5H2O, add it to 740 g of deionized water, and then add 20 g of solid sodium hydroxide. Stir and dissolve at 40 °C. At the same time, weigh 270 g of Al2(SO4)3·18H2O, add it to 415 g of deionized water, and stir and dissolve at 40 °C. Subsequently, under stirring at 600 r / min, slowly drip the aluminum sulfate solution into the sodium silicate solution. After the addition is completed, raise the temperature to 60 °C and age for 4 h, and the aging pH is 8.91. After aging, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 200 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 600 °C for 6 h to obtain an amorphous silica-alumina microsphere carrier material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0038] Example 3

[0039] Weigh 300 g of Na2SiO3·5H2O and add it to 760 g of deionized water. Stir and dissolve it at 40 °C. Meanwhile, weigh 224 g of Al2(SO4)3·18H2O and add it to 345 g of deionized water. Stir and dissolve it at 40 °C. After dissolution, under stirring at 600 r / min, slowly add the aluminum sulfate solution dropwise to the sodium silicate solution. After addition, raise the temperature to 60 °C and age for 4 h, with the aging pH being 8.16. After aging, centrifuge to separate the solid and liquid, and wash with deionized water to obtain the filter cake. Add 200 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 600 °C for 6 h to obtain an amorphous silica-alumina microsphere support material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0040] The scanning electron microscope results are shown in Figure 1 , and the particle size distribution of the microspheres is shown in Figure 2 . The characterization results show that the surface of the microspheres is round, smooth, and without cracking, and the particle size range is 40 - 250 μm.

[0041] Example 4

[0042] Weigh 300 g of Na2SiO3·5H2O and add it to 760 g of deionized water. Stir and dissolve it at 40 °C. Meanwhile, weigh 200 g of Al2(SO4)3·18H2O and add it to 290 g of deionized water. Stir and dissolve it at 40 °C. After dissolution, add 19.5 g of 98 wt.% concentrated sulfuric acid and stir evenly. Subsequently, under stirring at 600 r / min, slowly add the acidified aluminum sulfate solution dropwise to the sodium silicate solution. After addition, raise the temperature to 60 °C and age for 4 h, with the aging pH being 8.86. After aging, centrifuge to separate the solid and liquid, and wash the filter cake with deionized water to remove impurity ions. Add 180 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 600 °C for 6 h to obtain an amorphous silica-alumina microsphere support material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0043] Example 5

[0044] Weigh 300 g of Na2SiO3·5H2O and add it to 760 g of deionized water. Stir and dissolve it at 40 °C. Meanwhile, weigh 157 g of Al2(SO4)3·18H2O and add it to 195 g of deionized water. Stir and dissolve it at 40 °C. After complete dissolution, add 48.5 g of 98 wt.% concentrated sulfuric acid and stir evenly. Subsequently, under stirring at 600 r / min, slowly drop the acidified aluminum sulfate solution into the sodium silicate solution. After addition, raise the temperature to 60 °C and age for 4 h. The aging pH is 8.91. After aging, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 180 g of deionized water to the filter cake, stir to make a slurry, filter out large particles, and then perform spray drying. The obtained sample is calcined in a muffle furnace at 600 °C for 6 h to obtain an amorphous silica-alumina microsphere support material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0045] Example 6

[0046] Weigh 300 g of Na2SiO3·5H2O and add it to 760 g of deionized water. Stir and dissolve it at 40 °C. Meanwhile, weigh 225 g of Al(NO3)3·9H2O and add it to 246 g of deionized water. Stir and dissolve it at 40 °C. After complete dissolution, add 38.0 g of 68 wt.% concentrated nitric acid and stir evenly. Subsequently, under stirring at 600 r / min, slowly drop the acidified aluminum nitrate solution into the sodium silicate solution. After addition, raise the temperature to 60 °C and age for 4 h. The aging pH is 8.63. After aging, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 180 g of deionized water to the filter cake, stir to make a slurry, filter out large particles, and then perform spray drying. The obtained sample is calcined in a muffle furnace at 600 °C for 6 h to obtain an amorphous silica-alumina microsphere support material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0047] Example 7

[0048] Weigh 300 g of Na2SiO3·5H2O and add it to 760 g of deionized water. Stir and dissolve it at 40 °C. Meanwhile, weigh 80 g of AlCl3 and add it to 185 g of deionized water. Stir and dissolve it at 40 °C. After complete dissolution, add 41.3 g of 38 wt.% concentrated hydrochloric acid and stir evenly. Subsequently, under stirring at 600 r / min, slowly drop the acidified aluminum chloride solution into the sodium silicate solution. After addition, raise the temperature to 60 °C and age for 4 h. The aging pH is 8.46. After aging, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 180 g of deionized water to the filter cake, stir to make a slurry, filter out large particles, and then perform spray drying. The obtained sample is calcined in a muffle furnace at 600 °C for 6 h to obtain an amorphous silica-alumina microsphere support material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0049] Example 8

[0050] Weigh 300 g of Na2SiO3·5H2O and add it to 2500 g of deionized water. Stir and dissolve it at 20 °C. Meanwhile, weigh 224 g of Al2(SO4)3·18H2O and add it to 1500 g of deionized water. Stir and dissolve it at 20 °C. Subsequently, under stirring at 600 r / min, slowly drip the aluminum sulfate solution into the sodium silicate solution. After the addition is completed, raise the temperature to 80 °C and age for 6 h, with the aging pH being 8.37. After aging, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 180 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 750 °C for 8 h to obtain an amorphous silica-alumina microsphere carrier material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0051] Example 9

[0052] Weigh 300 g of Na2SiO3·5H2O and add it to 550 g of deionized water. Stir and dissolve it at 20 °C. Meanwhile, weigh 224 g of Al2(SO4)3·18H2O and add it to 1500 g of deionized water. Stir and dissolve it at 20 °C. Subsequently, under stirring at 600 r / min, slowly drip the aluminum sulfate solution into the sodium silicate solution. After the addition is completed, raise the temperature to 80 °C and age for 6 h, with the aging pH being 8.22. After aging, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 180 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 600 °C for 6 h to obtain an amorphous silica-alumina microsphere carrier material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0053] Example 10

[0054] Weigh 300 g of Na2SiO3·5H2O and add it to 2500 g of deionized water. Stir and dissolve it at 60 °C. Meanwhile, weigh 224 g of Al2(SO4)3·18H2O and add it to 1500 g of deionized water. Stir and dissolve it at 20 °C. Subsequently, under stirring at 600 r / min, slowly drip the aluminum sulfate solution into the sodium silicate solution. After the addition is completed, raise the temperature to 80 °C and age for 2 h, with the aging pH being 8.45. After aging, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 180 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 600 °C for 6 h to obtain an amorphous silica-alumina microsphere carrier material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1 and Figure 3 。

[0055] Figure 3 The results show that the carrier exhibits a type IV adsorption isotherm with an H1-type hysteresis loop, indicating a typical mesoporous structure with an average pore diameter of 45.8 nm.

[0056] Example 11

[0057] Weigh 110 g of Na2SiO3·5H2O and add it to 800 g of deionized water. Stir and dissolve it at 40 °C. After complete dissolution, weigh 144 g of a water glass solution with M = 2.4 and a silica content of 25 wt.%, and add it to the sodium silicate solution. Stir evenly. Weigh 200 g of Al2(SO4)3·18H2O and add it to 275 g of deionized water. Stir and dissolve it at 40 °C. Subsequently, under stirring at 600 r / min, slowly drip the aluminum sulfate solution into the sodium silicate solution. After addition, age at 40 °C for 4 h, and the aging pH is 9.02. After aging, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 220 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 600 °C for 6 h to obtain an amorphous silica-alumina microsphere carrier material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0058] Example 12

[0059] Weigh 340 g of a water glass solution with M = 2.68 and a silica content of 25 wt.%, add it to 790 g of water, and then add 62 g of solid sodium hydroxide. Stir evenly. Weigh 225 g of Al2(SO4)3·18H2O and add it to 820 g of deionized water. Stir and dissolve it at 40 °C. Subsequently, under stirring at 600 r / min, slowly drip the aluminum sulfate solution into the water glass solution. After addition, age at 40 °C for 4 h, and the aging pH is 8.80. After aging, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 220 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 600 °C for 6 h to obtain an amorphous silica-alumina microsphere carrier material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0060] Example 13

[0061] Weigh 300 g of Na2SiO3·5H2O, add it to 740 g of deionized water, then add 25 g of solid potassium hydroxide, and stir to dissolve at 60°C. At the same time, weigh 270 g of Al2(SO4)3·18H2O, add it to 415 g of deionized water, and stir to dissolve at 60°C. Subsequently, under stirring at 600 r / min, slowly drip the aluminum sulfate solution into the sodium silicate solution. After the addition is completed, age at 60°C for 2 h, and the aging pH is 8.52. After aging is completed, centrifuge to separate the solid and liquid, wash the filter cake with deionized water to remove impurity ions. Add 200 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 600°C for 6 h to obtain an amorphous silica-alumina microsphere carrier material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1.

[0062] Comparative Example 1 Weigh 300 g of Na2SiO3·5H2O, add it to 760 g of deionized water, and stir to dissolve at 40°C. At the same time, weigh 224 g of Al2(SO4)3·18H2O, add it to 345 g of deionized water, and stir to dissolve at 40°C. After dissolution is completed, under stirring at 600 r / min, slowly drip the sodium silicate solution and the aluminum sulfate solution into a three-necked flask for reaction simultaneously. After the addition is completed, heat up to 60°C and age for 4 h, and the aging pH is 8.64. After aging is completed, centrifuge to separate the solid and liquid, and wash with deionized water to obtain a filter cake. Add 200 g of deionized water to the filter cake and stir to make a slurry. After filtering out large particles, perform spray drying. The obtained sample is calcined in a muffle furnace at 600°C for 6 h to obtain an amorphous silica-alumina microsphere carrier material. Its specific surface area, pore volume, pore diameter, and silica-alumina ratio are shown in Table 1 and Figure 4 .

[0063] Figure 4 The results show that the carrier exhibits a type IV adsorption isotherm with an H1-type hysteresis loop, indicating a typical mesoporous structure and a relatively wide pore size distribution. The scanning electron microscope results are shown in Figure 5 , and the surface of the microspheres is severely cracked, and there is a phenomenon of sphere fragmentation.

[0064] Table 1 Pore structure, elemental composition, and attrition index of the samples

[0065] From Table 1, Figure 4 , Figure 5(Comparative Example 1) It can be seen that the amorphous silica-alumina support prepared by the coprecipitation method of sodium silicate and aluminum sulfate has a relatively low specific surface area and mesopore volume, a wide pore size distribution, and there are phenomena such as cracking on the surface of the microspheres and fragmentation of the spheres, and it does not have wear resistance. The reason is that during the coprecipitation process, crystal nucleation and growth occur simultaneously, and particles of different sizes are generated according to the different times when the materials enter the mixed liquid system, and the particle size distribution is relatively wide, resulting in a poor pore structure of the obtained materials.

[0066] In the improved synthesis process of the present invention, the nucleation and growth of the crystal grains occur simultaneously, ensuring the uniformity of the particles. The prepared product has a higher specific surface area, large-sized mesopores and large pore volume (Examples 1 to 13). At the same time, the microspheres obtained by this method have good wear resistance (attrition index 0.7% to 1.6%), because the particles shrink evenly during drying shrinkage, ensuring the good strength of the microsphere support. In addition, the contents of silica and alumina in the product can be adjusted according to requirements. Figure 2 It can be seen that the microspheres obtained in Example 3 show better roundness. The microspheres in Comparative Example 1 have poor sphericity and surface cracking, which may be caused by the relatively large primary particles and uneven shrinkage during the formation of the spheres.

Claims

1. An amorphous silica-alumina microsphere carrier material, based on the dry basis weight of the amorphous silica-alumina microsphere carrier material, the silica content is 50-80 wt.%, and the mass percentage content of alumina is 15-40 wt.%.

2. The amorphous silica-alumina microsphere carrier material according to claim 1, wherein The specific surface area of the amorphous silica-alumina microsphere carrier material is 200-400 m 2 / g, the mesopore volume is 0.80-1.45 cm 3 / g, the average pore diameter is 15-50 nm, and the mass ratio of silica to alumina is (1.5-4.8):

1.

3. A preparation method of the amorphous silica-alumina microsphere carrier material according to claim 1 or 2, comprising the following steps: (1) Adding an alkali to an aqueous solution of a silicon source, and stirring evenly to obtain a silicon-containing solution; (2) Adding an inorganic acid to an aqueous solution of an aluminum source, and stirring evenly to obtain an aluminum-containing solution; (3) Slowly dropping the aluminum-containing solution obtained in step (2) into the silicon-containing solution obtained in step (1) for reaction, and aging for a certain time at a certain pH and temperature after the addition is completed; (4) Filtering and washing with water the material obtained in step (3) to obtain a filter cake; (5) Dispersing the filter cake obtained in step (4) in water to make a slurry; (6) Spray-drying and roasting the slurry obtained in step (5) to obtain a finished product.

4. The preparation method according to claim 3, characterized in that, The silicon source is one or a combination of sodium silicate or water glass; the aluminum source is one of aluminum sulfate, aluminum nitrate or aluminum chloride.

5. The preparation method according to claim 3, characterized in that, The alkali is sodium hydroxide or potassium hydroxide; the inorganic acid is one of concentrated sulfuric acid, concentrated nitric acid or concentrated hydrochloric acid.

6. The preparation method according to claim 3, characterized in that, In step (3), the atomic ratio of silicon atoms in the silicon source to aluminum atoms in the aluminum source is (3-6):

1.

7. The preparation method according to claim 3, characterized in that In step (3), the aging pH is controlled at 7-9.

8. The preparation method according to claim 3, wherein In step (3), the aging temperature is 40-80 °C.

9. The preparation method according to claim 3, characterized in that, In step (5), the solid content in the gel obtained after the filter cake is slurried is 5-15%.

10. The preparation method according to claim 3, characterized in that, In step (6), the roasting temperature is 550-750 °C.

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