Preparation process of bimodal mesoporous alumina carrier

Abstract

The invention provides a preparation process of a double-mesoporous alumina carrier, and belongs to the technical field of catalysts, and the preparation process comprises the following steps: step S1, adding konjac glucomannan powder into a citric acid solution, adjusting the pH value, and stirring at normal temperature to form transparent colloid; s2, adding sodium lignin sulfonate and SiO2 nanoparticles into a lauryl sodium sulfate solution, and stirring to obtain modified sodium lignin sulfonate; and S3, mixing pseudo-boehmite, transparent colloid and modified sodium lignin sulfonate, defoaming, heating, adding calcium chloride, mixing, kneading, heating, drying and roasting to obtain the double-mesoporous alumina carrier. According to the technical scheme provided by the invention, the purposes of uniform distribution of two kinds of mesopores and good carrier strength of the alumina carrier are achieved.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and specifically to a preparation process for a dual mesoporous alumina support. Background Technology

[0002] Dual-mesoporous materials are a novel type of porous material developed in recent years based on mesoporous materials. These materials possess two mesoporous structures with different pore sizes: large mesopores allow molecules of larger diameters to enter and, as channels for mass transport, exhibit low diffusion resistance; small mesopores serve as adsorption sites and reaction sites, providing a larger active surface area, exhibiting better shape-selective catalysis capabilities while improving the dispersibility of active components. This characteristic of dual-mesoporous materials makes them highly promising for applications in heterogeneous catalysis and adsorption separation involving large molecules.

[0003] Patent application CN101214454A discloses a method for preparing macroporous alumina with a dual-pore distribution. The method involves mixing alumina, a pore-forming agent, and curing silica, then ball-milling the mixture. The resulting mixture is then mixed with an aqueous solution containing cationic surfactants, extrusion aids, and adhesive solvents, kneaded into a plastic body, treated in a steam atmosphere, dried, and calcined to obtain the alumina support. While this method achieves a dual-pore distribution, the pore distribution is not uniform. Patent application CN1249208A discloses a mesoporous alumina support and its preparation method. This method involves mixing one or more pseudo-boehmite dry adhesives prepared from different raw material routes with carbon black and surfactants, followed by gelation, molding, drying, and calcination. However, this method exhibits poor strength, and when applied in fixed-bed, fluidized-bed, or moving-bed reactors, the pulverization of the support can affect catalyst performance. Therefore, a preparation process for a dual-mesoporous alumina support is needed to address the problems of the existing technologies. Summary of the Invention

[0004] In view of this, the present invention provides a preparation process for a dual-mesoporous alumina carrier, which achieves the purpose of uniform mesoporous distribution and good strength of the alumina carrier.

[0005] The specific solution of this invention is as follows: a preparation process for a dual-mesoporous alumina carrier includes the following steps: Step S1: Add konjac glucomannan powder to citric acid solution, adjust pH, and stir at room temperature to form a transparent colloid; Step S2: Add sodium lignosulfonate and SiO2 nanoparticles to sodium dodecyl sulfate solution and stir to obtain modified sodium lignosulfonate. Step S3: Mix boehmite, transparent colloid and modified sodium lignosulfonate, degas, heat, add calcium chloride, mix and knead, heat, dry and calcine to obtain a dual mesoporous alumina carrier.

[0006] Konjac glucomannan can form a three-dimensional gel network in an acidic environment through hydrogen bonding and hydrophobic interactions. When the system is heated to 50°C, the gel strengthens and the viscosity increases. At 60°C, the hydrogen bonds break, causing the gel to disintegrate and leaving behind a uniform nanoporous template with a pore size of 3-5 nm. After modification with sodium lignin sulfonate, some areas of the lignin surface become positively charged, interacting with the negatively charged konjac glucomannan through Ca2+ and Ca2+. 2+ Bridging forms aggregates, which break down under shear force. After calcination and shrinkage, they form mesopores of 15-25 nm. Konjac glucomannan and modified sodium lignin sulfonate achieve pore hierarchical separation through dynamic phase separation, resulting in alumina carriers with dual mesopores and uniform pore size distribution.

[0007] Under nitrogen protection, konjac glucomannan carbonizes after calcination to form porous carbon, which can form a composite structure with γ-Al₂O₃, increasing the strength of the support. Lignin carbonization generates ordered carbon fibers that intersect at the γ-Al₂O₃ grain boundaries, inhibiting crack propagation under compressive stress and further enhancing the support's strength. Furthermore, the modified sodium lignin sulfonate contains SiO₂ nanoparticles, which help improve the hardness of the support structure. Simultaneously, the sulfonic acid groups in sodium lignin sulfonate are converted to -SO₄ groups upon calcination at 550℃. x The group provides Brønsted acid active sites, which can enhance the adsorption capacity of the alumina support.

[0008] Preferably, in step S1, the pH is 4-4.5.

[0009] Preferably, in step S1, the stirring speed at room temperature is 300-400 r / min, and the time is 20-40 min.

[0010] Preferably, in step S2, the stirring speed is 200-300 r / min and the stirring time is 1-2 h.

[0011] Preferably, in step S3, the pore volume of the pseudoboehmite is 0.5-0.7 cm. 3 / g and 0.8-1.2cm 3 / g.

[0012] It helps to form a uniform distribution of dual mesopores in the carrier.

[0013] Preferably, the weight ratio of pseudoboehmite with a pore volume of 0.5-0.7 cm3 / g to pseudoboehmite with a pore volume of 0.8-1.2 cm3 / g is 1:2.

[0014] Preferably, in step S3, the kneading speed is 10-15 r / min, the time is 20-30 min, and the heating temperature is 60-65℃.

[0015] Preferably, in step S3, the drying operation includes the following steps: placing the kneaded material into a drying oven, heating it to 50°C and holding it for 1 hour, then heating it to 65°C and holding it for 2 hours, and finally heating it to 85°C and holding it for 1.5 hours.

[0016] The drying process employs a gradient control method. The temperature is raised to 50°C while maintaining the material's moisture content at 70%. This high humidity delays surface hardening and promotes the directional migration of internal moisture through capillary force, preserving the template pores of konjac glucomannan. The temperature is then raised to 65°C, causing the material's moisture content to slowly decrease to 40%, resulting in phase separation and the formation of bimodal mesoporous structures. Finally, the temperature is raised to 85°C for dehydration, achieving pore shaping.

[0017] Preferably, in step S3, the calcination operation includes the following steps: introducing nitrogen gas, heating to 300°C at a rate of 2°C / min, introducing air, and then heating to 550°C at a rate of 1°C / min, and maintaining the temperature for 3-4 hours.

[0018] The temperature is raised to 300℃ to achieve carbonization and degumming, removing volatile components while retaining the carbon skeleton and carbon fibers; the temperature is raised to 550℃ to achieve pseudo-boehmite crystallization; the temperature is maintained at 550℃ to complete the crystal transformation and form a stable pore structure.

[0019] Preferably, the raw materials include the following parts by weight: The mixture consists of 300-360 parts of boehmite, 2.5-4 parts of transparent colloid, 1.5-2 parts of modified sodium lignosulfonate, and 0.1-0.3 parts of calcium chloride solution.

[0020] Preferably, the transparent colloid comprises the following raw materials in parts by weight: 3-5 parts konjac glucomannan powder, 70-80 parts deionized water, and 0.5-1 parts citric acid.

[0021] Preferably, the modified sodium lignosulfonate comprises the following raw materials in parts by weight: 10-20 parts sodium lignosulfonate, 1-1.5 parts SiO2 nanoparticles, and 0.1-0.5 parts sodium dodecyl sulfate solution.

[0022] The present invention uses the components of this weight proportion to obtain a dual mesoporous alumina carrier with uniform mesoporous distribution, and the obtained carrier has good mechanical properties and is not easy to pulverize.

[0023] The above-described technical solution of the present invention has at least the following beneficial effects: (1) Konjac glucomannan can form a three-dimensional gel network through hydrogen bonding and hydrophobic interactions. When heated to 60℃, its hydrogen bonds break, causing the gel to disintegrate and leaving a uniform nanoporous template with a pore size of 3-5 nm. After modification, sodium lignin sulfonate has a positively charged surface area on the lignin, which interacts with the negatively charged konjac glucomannan through Ca2+. 2+ The bridged aggregates are formed, which break down under shear force. After calcination and shrinkage, they form mesopores of 15-25 nm, achieving a uniform distribution of dual mesopores in the carrier.

[0024] (2) Under nitrogen protection, konjac glucomannan is carbonized after roasting to form porous carbon, which can form a composite structure with γ-Al2O3 to increase the strength of the carrier; after carbonization, lignin can generate ordered carbon fibers, which are interspersed in the γ-Al2O3 grain boundaries, inhibiting the crack propagation of the carrier under pressure and further improving the strength of the carrier.

[0025] (3) The modified sodium lignosulfonate contains SiO2 nanoparticles, which helps to improve the hardness of the carrier structure. Meanwhile, the sulfonic acid groups in the sodium lignosulfonate are converted to -SO4 after calcination. x The group provides Brønsted acid active sites, which can enhance the adsorption capacity of the alumina support. Attached Figure Description

[0026] Figure 1 This is a scanning electron microscope image of the dual mesoporous alumina support prepared in Example 1; Figure 2 The image shows the pore size distribution of the dual mesoporous alumina support prepared in Example 2. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0028] Example 1 Slowly add 3g of konjac glucomannan powder to 80g of citric acid solution, control the pH to 4-4.5, and stir at 350r / min at room temperature for 30min to form a transparent colloid.

[0029] 10g of sodium lignosulfonate and 1g of SiO2 nanoparticles were added to 90g of 0.5% sodium dodecyl sulfate solution, stirred at 250r / min for 1.5h, and filtered to obtain modified sodium lignosulfonate.

[0030] The pore volume is 0.5-0.7 cm. 3 / g of 100g of pseudoboehmite with a pore volume of 0.8-1.2cm 3 Mix 200g of pseudoboehmite in a 1:2 ratio and add it to a kneader. Then add 2.5g of transparent colloid and 2g of modified sodium lignosulfonate. Mix evenly at room temperature, degas, and heat to 50℃ at a rate of 2℃ / min. Hold for 15min. Then add 0.1g of calcium chloride and mix at a rate of 10r / min for 30min. Raise the temperature to 60-65℃, increase the kneading speed to 40r / min, and hold for 20min to obtain the kneaded material.

[0031] The kneaded material was placed in a drying oven, heated to 50°C and held for 1 hour, then heated to 65°C and held for 2 hours, and finally heated to 85°C and held for 1.5 hours. Segmented calcination was then performed: in the first stage, nitrogen gas was introduced, and the temperature was increased to 300°C at a rate of 2°C / min; in the second stage, air was introduced, and the temperature was increased to 550°C at a rate of 1°C / min; in the third stage, the temperature was held at 550°C for 3 hours to obtain a dual-mesoporous alumina carrier.

[0032] Example 2 Slowly add 4g of konjac glucomannan powder to 75g of citric acid solution, control the pH to 4-4.5, and stir at 400r / min at room temperature for 25min to form a transparent colloid.

[0033] 20g of sodium lignosulfonate and 1.5g of SiO2 nanoparticles were added to 80g of 0.5% sodium dodecyl sulfate solution, stirred at 200-300r / min for 1-2h, and filtered to obtain modified sodium lignosulfonate.

[0034] The pore volume is 0.5-0.7 cm. 3 / g of 120g of pseudoboehmite with a pore volume of 0.8-1.2cm 3 Mix 240g of pseudoboehmite in a 1:2 ratio and add it to a kneader. Then add 3g of transparent colloid and 2g of modified sodium lignosulfonate. Mix evenly at room temperature, degas, and heat to 50℃ at a rate of 2℃ / min. Hold for 12min. Then add 0.3g of calcium chloride and mix at a rate of 15r / min for 20min. Raise the temperature to 60-65℃, increase the kneading speed to 40r / min, and hold for 20min to obtain the kneaded material.

[0035] The kneaded material was placed in a drying oven, heated to 50°C and held for 1 hour, then heated to 65°C and held for 2 hours, and finally heated to 85°C and held for 1.5 hours. Segmented calcination was then performed: in the first stage, nitrogen gas was introduced, and the temperature was increased to 300°C at a rate of 2°C / min; in the second stage, air was introduced, and the temperature was increased to 550°C at a rate of 1°C / min; in the third stage, the temperature was held at 550°C for 4 hours to obtain a dual-mesoporous alumina carrier.

[0036] Example 3 Slowly add 3g of konjac glucomannan powder to 75g of citric acid solution, control the pH to 4-4.5, and stir at 300r / min at room temperature for 40min to form a transparent colloid.

[0037] 12g of sodium lignosulfonate and 1g of SiO2 nanoparticles were added to 100g of 0.5% sodium dodecyl sulfate solution, stirred at 300r / min for 1h, and filtered to obtain modified sodium lignosulfonate.

[0038] The pore volume is 0.5-0.7 cm. 3 / g of 110g of pseudoboehmite with a pore volume of 0.8-1.2cm 3 Mix 220g of pseudoboehmite in a 1:2 ratio and add it to a kneader. Then add 2.5g of transparent colloid and 2g of modified sodium lignosulfonate. Mix evenly at room temperature, degas, and heat to 50℃ at a rate of 2℃ / min. Hold for 18min. Then add 0.2g of calcium chloride and mix at a rate of 12r / min for 25min. Raise the temperature to 60-65℃, increase the kneading speed to 40r / min, and hold for 20min to obtain the kneaded material.

[0039] The kneaded material was placed in a drying oven, heated to 50°C and held for 1 hour, then heated to 65°C and held for 2 hours, and finally heated to 85°C and held for 1.5 hours. Segmented calcination was then performed: in the first stage, nitrogen gas was introduced, and the temperature was increased to 300°C at a rate of 2°C / min; in the second stage, air was introduced, and the temperature was increased to 550°C at a rate of 1°C / min; in the third stage, the temperature was held at 550°C for 3 hours to obtain a dual-mesoporous alumina carrier.

[0040] Example 4 Slowly add 5g of konjac glucomannan powder to 80g of citric acid solution, control the pH to 4-4.5, and stir at 350r / min at room temperature for 25min to form a transparent colloid.

[0041] 15g of sodium lignosulfonate and 1.5g of SiO2 nanoparticles were added to 90g of 0.5% sodium dodecyl sulfate solution, stirred at 200r / min for 1.5h, and filtered to obtain modified sodium lignosulfonate.

[0042] The pore volume is 0.5-0.7 cm. 3 / g of 120g of pseudoboehmite with a pore volume of 0.8-1.2cm 3 Mix 240g of pseudoboehmite in a 1:2 ratio and add it to a kneader. Then add 3g of transparent colloid and 1.5g of modified sodium lignosulfonate. Mix evenly at room temperature, degas, and heat to 50℃ at a rate of 2℃ / min. Hold for 15min. Then add 0.15g of calcium chloride and mix at a rate of 15r / min for 25min. Raise the temperature to 60-65℃, increase the kneading speed to 40r / min, and hold for 20min to obtain the kneaded material.

[0043] The kneaded material was placed in a drying oven, heated to 50°C and held for 1 hour, then heated to 65°C and held for 2 hours, and finally heated to 85°C and held for 1.5 hours. Segmented calcination was then performed: in the first stage, nitrogen gas was introduced, and the temperature was increased to 300°C at a rate of 2°C / min; in the second stage, air was introduced, and the temperature was increased to 550°C at a rate of 1°C / min; in the third stage, the temperature was held at 550°C for 3.5 hours to obtain a dual-mesoporous alumina carrier.

[0044] Example 5 Slowly add 4g of konjac glucomannan powder to 70g of citric acid solution, control the pH to 4-4.5, and stir at 400r / min at room temperature for 25min to form a transparent colloid.

[0045] 10g of sodium lignosulfonate and 1.5g of SiO2 nanoparticles were added to 80g of 0.5% sodium dodecyl sulfate solution, stirred at 200-300r / min for 1-2h, and filtered to obtain modified sodium lignosulfonate.

[0046] The pore volume is 0.5-0.7 cm. 3 / g of 100g of pseudoboehmite with a pore volume of 0.8-1.2cm 3 Mix 200g of pseudoboehmite in a 1:2 ratio and add it to a kneader. Then add 3.5g of transparent colloid and 1.5g of modified sodium lignosulfonate. Mix evenly at room temperature, degas, and heat to 50℃ at a rate of 2℃ / min. Hold for 18min. Then add 0.25g of calcium chloride and mix at a rate of 10r / min for 30min. Raise the temperature to 60-65℃, increase the kneading speed to 40r / min, and hold for 20min to obtain the kneaded material.

[0047] The kneaded material was placed in a drying oven, heated to 50°C and held for 1 hour, then heated to 65°C and held for 2 hours, and finally heated to 85°C and held for 1.5 hours. Segmented calcination was then performed: in the first stage, nitrogen gas was introduced, and the temperature was increased to 300°C at a rate of 2°C / min; in the second stage, air was introduced, and the temperature was increased to 550°C at a rate of 1°C / min; in the third stage, the temperature was held at 550°C for 4 hours to obtain a dual-mesoporous alumina carrier.

[0048] Example 6 Slowly add 5g of konjac glucomannan powder to 75g of citric acid solution, control the pH to 4-4.5, and stir at 300r / min at room temperature for 35min to form a transparent colloid.

[0049] 18g of sodium lignosulfonate and 1.5g of SiO2 nanoparticles were added to 100g of 0.5% sodium dodecyl sulfate solution, stirred at 200r / min for 2h, and filtered to obtain modified sodium lignosulfonate.

[0050] The pore volume is 0.5-0.7 cm. 3 / g of 110g of pseudoboehmite with a pore volume of 0.8-1.2cm 3 Mix 220g of pseudoboehmite in a 1:2 ratio and add it to a kneader. Then add 2.5g of transparent colloid and 2g of modified sodium lignosulfonate. Mix evenly at room temperature, degas, and heat to 50℃ at a rate of 2℃ / min. Hold for 16min. Then add 0.2g of calcium chloride and mix at a rate of 12r / min for 30min. Raise the temperature to 60-65℃, increase the kneading speed to 40r / min, and hold for 20min to obtain the kneaded material.

[0051] The kneaded material was placed in a drying oven, heated to 50°C and held for 1 hour, then heated to 65°C and held for 2 hours, and finally heated to 85°C and held for 1.5 hours. Segmented calcination was then performed: in the first stage, nitrogen gas was introduced, and the temperature was increased to 300°C at a rate of 2°C / min; in the second stage, air was introduced, and the temperature was increased to 550°C at a rate of 1°C / min; in the third stage, the temperature was held at 550°C for 3 hours to obtain a dual-mesoporous alumina carrier.

[0052] Example 7 Slowly add 3g of konjac glucomannan powder to 75g of citric acid solution, control the pH to 4-4.5, and stir at 300r / min at room temperature for 30min to form a transparent colloid.

[0053] 15g of sodium lignosulfonate and 1.2g of SiO2 nanoparticles were added to 85g of 0.5% sodium dodecyl sulfate solution, stirred at 300r / min for 1h, and filtered to obtain modified sodium lignosulfonate.

[0054] The pore volume is 0.5-0.7 cm. 3 / g of pseudoboehmite and pore volume of 0.8-1.2cm 3 Mix 230g of pseudoboehmite in a 1:2 ratio and add it to a kneader. Then add 4g of transparent colloid and 1.5g of modified sodium lignosulfonate. Mix evenly at room temperature, degas, and heat to 50℃ at a rate of 2℃ / min. Hold for 14min. Then add 0.3g of calcium chloride and mix at a rate of 15r / min for 20min. Raise the temperature to 60-65℃, increase the kneading speed to 40r / min, and hold for 20min to obtain the kneaded material.

[0055] The kneaded material was placed in a drying oven, heated to 50°C and held for 1 hour, then heated to 65°C and held for 2 hours, and finally heated to 85°C and held for 1.5 hours. Segmented calcination was then performed: in the first stage, nitrogen gas was introduced, and the temperature was increased to 300°C at a rate of 2°C / min; in the second stage, air was introduced, and the temperature was increased to 550°C at a rate of 1°C / min; in the third stage, the temperature was held at 550°C for 3.5 hours to obtain a dual-mesoporous alumina carrier.

[0056] Example 8 Slowly add 4g of konjac glucomannan powder to 80g of citric acid solution, control the pH to 4-4.5, and stir at 400r / min at room temperature for 20min to form a transparent colloid.

[0057] 15g of sodium lignosulfonate and 1g of SiO2 nanoparticles were added to 90g of 0.5% sodium dodecyl sulfate solution, stirred at 200r / min for 1.5h, and filtered to obtain modified sodium lignosulfonate.

[0058] The pore volume is 0.5-0.7 cm. 3 / g of 105g of pseudoboehmite with a pore volume of 0.8-1.2cm 3 Mix 210g of pseudoboehmite in a 1:2 ratio and add it to a kneader. Then add 3g of transparent colloid and 2g of modified sodium lignosulfonate. Mix evenly at room temperature, degas, and heat to 50℃ at a rate of 2℃ / min. Hold for 12min. Then add 0.15g of calcium chloride and mix at a rate of 15r / min for 25min. Raise the temperature to 60-65℃, increase the kneading speed to 40r / min, and hold for 20min to obtain the kneaded material.

[0059] The kneaded material was placed in a drying oven, heated to 50°C and held for 1 hour, then heated to 65°C and held for 2 hours, and finally heated to 85°C and held for 1.5 hours. Segmented calcination was then performed: in the first stage, nitrogen gas was introduced, and the temperature was increased to 300°C at a rate of 2°C / min; in the second stage, air was introduced, and the temperature was increased to 550°C at a rate of 1°C / min; in the third stage, the temperature was held at 550°C for 4 hours to obtain a dual-mesoporous alumina carrier.

[0060] The present invention also includes comparative examples and related experiments.

[0061] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that no transparent colloid was prepared, but the other components and preparation process were the same as in Example 1, and a dual mesoporous alumina carrier was prepared.

[0062] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that no modified sodium lignosulfonate was prepared. The other components and preparation process were the same as in Example 1, and a dual mesoporous alumina carrier was prepared.

[0063] Comparative Example 3 Comparative Example 3 uses a dual-mesoporous alumina carrier prepared using a large mesoporous alumina carrier and its preparation method disclosed in the patent document with authorization announcement number CN1089039C.

[0064] Performance testing The properties of the dual mesoporous alumina supports prepared in Examples 1-8 and Comparative Examples 1-3 were tested, and the results are shown in Table 1.

[0065] Table 1

[0066] As shown in Table 1 above, the carrier prepared in Comparative Example 1 has a similar pore size distribution range to that in Example 1, and the small mesopore size exceeds the expected range, indicating that the transparent colloid facilitates the formation of small mesopores in the carrier; combined with Figure 1 and Figure 2 As shown, the mesopores of the dual mesoporous alumina supports prepared in Examples 1 and 2 conform to the expected pore size distribution. Compared with Example 1, the support prepared in Comparative Example 2 has significantly larger mesopores and a more significant decrease in strength, indicating that the modified sodium lignin sulfonate helps to achieve a uniform distribution of mesopores and improve the strength of the support. The properties of the support prepared in Comparative Example 3 are all inferior to those in Examples 1-8, indicating that the dual mesoporous alumina support prepared by this scheme has better properties and meets the requirements for application in the catalytic field.

[0067] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A preparation process for a dual-mesoporous alumina carrier, characterized in that, Includes the following steps: Step S1: Add konjac glucomannan powder to citric acid solution, adjust pH, and stir at room temperature to form a transparent colloid; Step S2: Add sodium lignosulfonate and SiO2 nanoparticles to sodium dodecyl sulfate solution and stir to obtain modified sodium lignosulfonate. Step S3: Mix boehmite, transparent colloid and modified sodium lignosulfonate, degas, heat, add calcium chloride, mix and knead, heat, dry and calcine to obtain a dual mesoporous alumina carrier.

2. The preparation process of the dual-mesoporous alumina carrier according to claim 1, characterized in that, In step S1, the pH is 4-4.

5.

3. The preparation process of the dual-mesoporous alumina carrier according to claim 1, characterized in that, In step S1, the stirring speed at room temperature is 300-400 r / min, and the time is 20-40 min.

4. The preparation process of the dual-mesoporous alumina carrier according to claim 1, characterized in that, In step S2, the stirring speed is 200-300 r / min and the time is 1-2 h.

5. The preparation process of the dual-mesoporous alumina carrier according to claim 1, characterized in that, In step S3, the pore volume of the pseudoboehmite is 0.5-0.7 cm. 3 / g and 0.8-1.2cm 3 / g.

6. The preparation process of the dual-mesoporous alumina carrier according to claim 5, characterized in that, The pore volume is 0.5-0.7 cm. 3 / g of pseudoboehmite and a pore volume of 0.8-1.2cm 3 The weight ratio of pseudoboehmite is 1:

2.

7. The preparation process of the dual-mesoporous alumina carrier according to claim 1, characterized in that, In step S3, the kneading speed is 10-15 r / min, the time is 20-30 min, and the heating temperature is 60-65℃.

8. The preparation process of the dual-mesoporous alumina carrier according to claim 1, characterized in that, In step S3, the drying operation includes the following steps: placing the kneaded material into a drying oven, heating it to 50°C and holding it for 1 hour, then heating it to 65°C and holding it for 2 hours, and finally heating it to 85°C and holding it for 1.5 hours.

9. The preparation process of the dual-mesoporous alumina carrier according to claim 1, characterized in that, In step S3, the calcination operation includes the following steps: introducing nitrogen gas, heating to 300°C at a rate of 2°C / min, introducing air, and then heating to 550°C at a rate of 1°C / min, and maintaining the temperature for 3-4 hours.

10. The preparation process of the dual-mesoporous alumina carrier according to claim 1, characterized in that, The dual-mesoporous alumina carrier comprises the following raw materials in parts by weight: The composition consists of 300-360 parts of boehmite, 2.5-4 parts of transparent colloid, 1.5-2 parts of modified sodium lignosulfonate, and 0.1-0.3 parts of calcium chloride.

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