Intermediate-intermediate bimodal pore alumina support and method of making same

Abstract

The application discloses a meso-meso bimodal pore alumina carrier and a preparation method thereof. The average pore diameter of the carrier is 5-20nm, the smaller pore is 3-8nm, the larger pore is 8-30nm, the specific surface area is 120-300m 2 / g, and the pore volume is 0.3-0.6cm 3 / g. The meso-meso bimodal pore alumina carrier provided by the application can ensure the diffusion and adsorption of molecules in the pore channel, and can strengthen the collision between the molecules and the pore wall of the catalyst, so that the activity and selectivity of the catalyst are improved.

Description

Technical Field

[0001] This invention belongs to the field of hydrogenation catalyst technology, specifically relating to a meso-meso bimodal porous alumina support and its preparation method. Background Technology

[0002] The pore structure of a catalyst refers to the channels within the catalyst, categorized into macropores, mesopores, and micropores. Macropores are generally larger than 50 nanometers, mesopores range from 2 to 50 nanometers in size, and micropores are typically smaller than 2 nanometers. In addition, there are mesopores, which fall between mesopores and micropores. The pore structure of a catalyst plays a decisive role in the diffusion of reactant molecules and the emission of reaction products. Specifically, macropores can accommodate large reactant molecules, increasing the mass transport rate; mesopores can increase the surface area and the number of reaction sites on the catalyst, thereby improving the reaction rate and conversion; and micropores can provide more active sites, increasing the stability and selectivity of the catalyst.

[0003] Pore ​​structure is a crucial factor in catalyst design, and its control can improve catalyst activity, selectivity, and stability. For example, preparing high-porosity catalysts can increase reaction rates and selectivity while reducing the amount of active metal used; adjusting pore size distribution can yield highly selective catalysts for selective hydrogenation and heterogeneous catalytic reactions; and preparing porous catalysts can improve their stability and reusability, for example, in catalytic reduction and oxidation reactions. The pore structure of a catalyst is a vital factor in catalytic reactions, significantly impacting catalytic performance, selectivity, stability, and reusability. Pore structure plays a significant role in catalyst design and optimization, and it needs to be adjusted and improved through preparation techniques and pore structure control methods to achieve higher catalytic efficiency and metal utilization.

[0004] The pore structure of supported catalysts mainly originates from the support, therefore, controlling the pore structure of the support is crucial. Patent CN1188216C discloses a method for preparing an alumina support, with the pore diameters of the prepared alumina support concentrated in the ranges of 6nm-35nm and 100nm-2000nm, respectively. The alumina support prepared by this method can be used as a support for the production of heavy oil hydrotreating protective agents, demetallizing catalysts, and diffusion-controlled reaction process catalysts. Patent CN202210804839 discloses a heavy oil support exhibiting a bimodal pore distribution with diameters of 5-20nm and 100-500nm. The pore volume of pores with diameters of 5-20nm accounts for 50-80% of the total pore volume, the pore volume of pores with diameters of 100-500nm accounts for 19-40% of the total pore volume, and the pore volume of pores with diameters below 10nm does not exceed 20% of the total pore volume. Patent CN202110209242 discloses a bimodal porous support, exhibiting characteristic peaks at 25 nm and 480 nm. Pores with diameters between 20-50 nm account for 46.3% of the total pore volume, pores with diameters greater than 100 nm account for 38.2%, and pores with diameters less than 20 nm account for 15.5%. Patent CN202010351478 discloses a hydrogenation catalyst whose bimodal pore structure was determined by mercury intrusion porosimetry. The mesopore volume V, located at 3-100 nm, is 0.7-1.7 mL / g; the macropore volume V, located at 100-5000 nm, is 1.7-4.7 mL / g; and the total macropore volume V is 2.4-6.4 mL / g.

[0005] In summary, existing technologies have produced a series of alumina supports with specific pore distributions. However, the support preparation stage reduces the proportion of small pores, for example, pores below 6 nm, and both pore distributions are 3-100 nm and 100-5000 nm, suitable for catalytic reactions of large molecular systems (such as heavy oil hydrogenation). There is limited research on meso-meso-bimodal alumina supports where both pore sizes are concentrated in the 2-30 nm range. It is well known that during molecular diffusion in porous materials, two types of collisions influence the catalyst's activity and selectivity: collisions between molecules and the catalyst pore walls, and collisions between molecules. Intermolecular collisions tend to hinder molecules from reaching the catalyst pore walls. Therefore, to increase catalyst activity and selectivity, it is necessary to enhance collisions between molecules and the catalyst pore walls. For catalytic reactions of small molecular systems that do not require mixing (such as gasoline hydrogenation), due to the small size of the molecules, when the pore size is greater than 30 nm, collisions between molecules dominate. When the pore size is small (2-30 nm) or the gas concentration is very low, collisions between molecules and the catalyst pore walls dominate.

[0006] Therefore, it is necessary to develop a meso-meso-bimodal alumina support with both types of pores concentrated at 2-30 nm in the bimodal pore structure. This can ensure the diffusion and adsorption of molecules in the pores and enhance the collision between molecules and the pore walls of the catalyst, thereby improving the activity and selectivity of the catalyst. Summary of the Invention

[0007] The purpose of this invention is to provide a meso-meso bimodal porous alumina carrier to solve the problem of wide pore size distribution in existing bimodal porous alumina carriers.

[0008] Another object of the present invention is to provide a method for preparing a meso-meso bimodal porous alumina carrier.

[0009] To achieve the above objectives, the present invention provides a meso-meso-bimodal porous alumina support, wherein the support has an average pore size of 5–20 nm, a smaller pore size of 3–8 nm, a larger pore size of 8–30 nm, and a specific surface area of ​​120–300 m². 2 / g, pore volume 0.3~0.6cm 3 / g.

[0010] To achieve the above objectives, the present invention also provides a method for preparing the above-described meso-meso-bimodal porous alumina support, comprising the following steps:

[0011] S1, Alumina, water, inorganic pore expander and / or organic pore expander are mixed and extruded to obtain an extruded strip; in the XRD pattern of the alumina, the relative intensity of the peak with 2θ of 13 to 16.6° is 100.0%, the relative intensity of the peak with 2θ of 16.6 to 23.2° is 85 to 88%, the peak with 2θ of 23.17 to 53.79° is a diffuse scattering peak, and the relative intensity of the peak with 2θ of 53.79 to 75° is 55 to 60%;

[0012] S2, the extruded strip is matured, dried and calcined to obtain the carrier.

[0013] The method for preparing the meso-meso-bimodal porous alumina support of the present invention, wherein in the XRD pattern of the alumina, the characteristic peak angle of the peak with 2θ of 13-16.6° is 14-15°, the characteristic peak angle of the peak with 2θ of 16.6-23.2° is 19-20°, the peak with 2θ of 23.17-53.79° is a diffuse peak, and the characteristic peak angle of the peak with 2θ of 53.79-75° is 60.5-61.5°.

[0014] The method for preparing the meso-meso-bimodal porous alumina support of the present invention, wherein the XRD pattern of the alumina after calcination at 800℃ shows that the relative intensities of the peaks with 2θ values ​​of 14.69–23.74° are 54–58%, the relative intensities of the peaks with 2θ values ​​of 23.74–34.35° are 76–80%, the relative intensities of the peaks with 2θ values ​​of 34.35–39.04° are 100.0%, the relative intensities of the peaks with 2θ values ​​of 39.04–41.96° are 77–82%, the relative intensities of the peaks with 2θ values ​​of 41.96–52.52° are 62.5–68%, the relative intensities of the peaks with 2θ values ​​of 52.52–63.33° are 38.5–45%, and the relative intensities of the peaks with 2θ values ​​of 63.33–73.95° are 80.0–90%.

[0015] The method for preparing the meso-meso-bimodal porous alumina support of the present invention, wherein in the XRD pattern of the alumina after calcination at 800℃, the characteristic peak angles of the peaks with 2θ of 14.69–23.74° are 17.8–21.8°, the characteristic peak angles of the peaks with 2θ of 23.74–34.35° are 30.7–34.7°, and the characteristic peak angles of the peaks with 2θ of 34.35–39.04° are 35.4–36.5°. The characteristic peak angles of the peaks with 2θ values ​​of 9.4°, 39.04–41.96°, 43.7–47.7°, 58.8–62.8°, and 65.1–69.1° are also present.

[0016] The method for preparing the meso-meso bimodal porous alumina carrier of the present invention further includes step S3, which involves placing the carrier in a sealed high-pressure container and boiling it under autogenous pressure, followed by drying.

[0017] The method for preparing the meso-meso bimodal porous alumina carrier of the present invention uses an inorganic pore-expanding agent, which is one or more of activated carbon, urea, ammonium carbonate, and ammonia water.

[0018] The method for preparing the meso-meso-bimodal porous alumina carrier of the present invention uses an organic pore-expanding agent that is one or more of hydroxypropyl methylcellulose, starch, polyethylene glycol, polycarboxylic acid superplasticizer, glycerol, carboxymethyl cellulose, and polyvinylpyrrolidone.

[0019] The method for preparing the meso-meso bimodal porous alumina carrier of the present invention, based on 100% alumina mass, involves adding 1-20% of the inorganic pore-expanding agent and 1-20% of the organic pore-expanding agent.

[0020] The preparation method of the meso-meso bimodal porous alumina carrier of the present invention includes the following steps in step S2: aging conditions of 20-35℃ for 24-72h; drying temperature of 100-120℃; and calcination conditions of 200-900℃ for 2-6h, preferably calcination temperature of 500-800℃.

[0021] In the preparation method of the meso-meso bimodal porous alumina carrier of the present invention, the water boiling conditions in step S3 are 120-200℃ for 1-6h, preferably 130-180℃; the drying temperature is 100-120℃.

[0022] Beneficial effects of this invention:

[0023] The meso-meso-bimodal porous alumina support provided by this invention can ensure the diffusion and adsorption of molecules in the pores and enhance the collision between molecules and the catalyst pore walls for catalytic reactions of small molecule systems that do not require inclusion (such as gasoline hydrogenation), which is beneficial to improving the activity and selectivity of the catalyst. Attached Figure Description

[0024] Figure 1 The pore size distribution diagram is shown for carrier A prepared in Example 1;

[0025] Figure 2 The pore size distribution diagram of the carrier B prepared in Example 2;

[0026] Figure 3 Pore ​​size distribution of the carrier C prepared in Example 3;

[0027] Figure 4 Pore ​​size distribution of the carrier D prepared in Example 4;

[0028] Figure 5 Pore ​​size distribution of the carrier E prepared in Example 5;

[0029] Figure 6 Pore ​​size distribution of the carrier F prepared in Example 6;

[0030] Figure 7 Pore ​​size distribution of the carrier G prepared in Example 7;

[0031] Figure 8 Pore ​​size distribution diagram of the carrier H prepared in Example 8;

[0032] Figure 9 Pore ​​size distribution of carrier I prepared in Example 9;

[0033] Figure 10 The pore size distribution of the carrier J prepared for Comparative Example 1 is shown in the diagram.

[0034] Figure 11 The pore size distribution diagram is shown for the carrier J prepared in Comparative Example 2. Detailed Implementation

[0035] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0036] Example 1

[0037] Weigh 120g of No. 1 hydrated alumina powder (dry basis content 90wt%), add 1.8g of hydroxypropyl methylcellulose with a viscosity of 150,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and 12g of starch, and mix evenly; weigh 72g of deionized water, and slowly and evenly add it to the above materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on an extruder. After the extruded carrier is placed at 20℃ for 24 hours to mature, it is dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 800℃ for 3 hours to obtain carrier A. Its physicochemical properties are shown in Table 1, and the bimodal pore size is as follows. Figure 1 As shown.

[0038] 1# Hydrated alumina in dry state: 2θ angle and relative intensity peak

[0039]

[0040] 1# Hydrated alumina under 800°C calcination state: 2θ angle and relative intensity peak

[0041]

[0042]

[0043] Example 2

[0044] Weigh 100g of the aforementioned No. 1 hydrated alumina powder, add 1.5g of hydroxypropyl methylcellulose with a viscosity of 100,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and 3g of polycarboxylate superplasticizer, and mix evenly; weigh 55g of deionized water, slowly and evenly add it to the aforementioned materials, knead it into a plastic body in a kneader, and then extrude it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After the extruded carrier is left to mature at room temperature for 48 hours, it is dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 800℃ for 3 hours to obtain carrier B. Its physicochemical properties are shown in Table 1, and the bimodal pore size is as follows. Figure 2 As shown.

[0045] Example 3

[0046] Weigh 100g of the aforementioned No. 1 hydrated alumina powder; add 10g of hydroxypropyl methylcellulose with a viscosity of 150,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and mix evenly. Weigh 60g of deionized water and slowly and evenly add it to the aforementioned materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After the extruded carrier is left to mature at room temperature for 24 hours, it is dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 600℃ for 3 hours to obtain carrier C. Its physicochemical properties are shown in Table 1, and the bimodal pore size is as follows. Figure 3 As shown.

[0047] Example 4

[0048] Weigh 70g of No. 2 hydrated alumina powder and add 3g of hydroxypropyl methylcellulose with a viscosity of 150,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and mix evenly. Weigh 180g of deionized water and slowly and evenly add it to the above materials, kneading it into a plastic body in a kneader, and then extruding it into a clover shape with a diameter of 2mm on a hydraulic extruder. After the extruded carrier is left to mature at room temperature for 72 hours, it is dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 600℃ for 3 hours to obtain carrier D. Its physicochemical properties are shown in Table 1, and the bimodal pore size is as follows. Figure 4 As shown.

[0049] 2# Hydrated alumina in dry state: 2θ angle and relative intensity peak

[0050]

[0051] 2θ angle and relative intensity peak of hydrated alumina at 800°C

[0052] 2 theta angle / ° Characteristic peak angle / ° Relative intensity / % 15.5-23 20.5 54.26 24-34 34.0 76.87 35-38 39.0 100.0 39.5-41.0 41.5 79.25 42.5-52 47.0 64.21 54-62 62 39.0 65-72 68.5 83.66

[0053] Example 5

[0054] Weigh 100g of the aforementioned No. 2 hydrated alumina powder, add 1.5g of hydroxypropyl methylcellulose with a viscosity of 200,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and 20g of activated carbon powder, and mix evenly. Weigh 70g of deionized water and slowly and evenly add it to the aforementioned materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After the extruded carrier is left to mature at room temperature for 24 hours, it is dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 800℃ for 3 hours to obtain carrier E. Its physicochemical properties are shown in Table 1, and the bimodal pore size is as follows. Figure 5 As shown.

[0055] Example 6

[0056] Weigh 100g of the aforementioned No. 2 hydrated alumina powder, add 1.8g of hydroxypropyl methylcellulose with a viscosity of 100,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and 12g of urea, and mix thoroughly. Weigh 60g of deionized water and slowly and evenly add it to the aforementioned materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After the extruded carrier is left to mature at room temperature for 24 hours, it is dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 800℃ for 3 hours to obtain carrier F. Its physicochemical properties are shown in Table 1, and the bimodal pore size is as follows. Figure 6 As shown.

[0057] Example 7

[0058] The carrier strip prepared in Example 5 was weighed into a high-pressure reactor liner (5g), and a certain amount of deionized water was added. The mixture was boiled at 150°C for 2 hours to obtain carrier G. Its physicochemical properties are shown in Table 1. The bimodal pore size is as follows: Figure 7 As shown.

[0059] Example 8

[0060] The carrier strip prepared in Example 5 was weighed into a high-pressure reactor liner (5g), and a certain amount of deionized water was added. The mixture was boiled at 150°C for 4 hours to obtain carrier H. Its physicochemical properties are shown in Table 1. The bimodal pore size is as follows: Figure 8 As shown.

[0061] Example 9

[0062] The carrier strip prepared in Example 5 was weighed into a high-pressure reactor liner (5g), and a certain amount of deionized water was added. The mixture was boiled at 180°C for 2 hours to obtain carrier I. Its physicochemical properties are shown in Table 1. The bimodal pore size is as follows: Figure 9 As shown.

[0063] Comparative Example 1

[0064] Same as Example 1, except that different alumina is used. The XRD characterization results of the alumina used in this comparative example are as follows:

[0065] 3# Hydrated alumina in dry state: 2θ angle and relative intensity peak

[0066]

[0067]

[0068] 3# hydrated alumina under 800°C calcination state: 2θ angle and relative intensity peak

[0069] 2 theta angle / ° Characteristic peak angle / ° Relative intensity / % 15-23 19.1 56.20 24-42 37 92.96 42.5-49 45.73 100.00 56-63.5 60.5 34.08 64-70 66.85 87.89

[0070] The support J was prepared, and its physicochemical properties are shown in Table 1. The most probable pore size is as follows: Figure 10 As shown.

[0071] Comparative Example 2

[0072] Same as Example 1, except that there is no curing step.

[0073] The support K was prepared, and its physicochemical properties are shown in Table 1. The most probable pore size is as follows: Figure 11 As shown.

[0074] Table 1 Physicochemical properties of carriers A to K

[0075]

[0076] As can be seen from the table above, bimodal pore supports with different pore size distributions can be prepared by adjusting the preparation parameters. In addition, after boiling in water, the bimodal pore size of the support increases significantly, which is beneficial to the diffusion of reactant molecules inside the support.

[0077] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A meso-meso-bimodal porous alumina carrier, characterized in that, The carrier has an average pore size of 5–20 nm, smaller pores of 3–8 nm, larger pores of 8–30 nm, and a specific surface area of ​​120–300 m². 2 / g, pore volume 0.3~0.6cm 3 / g.

2. The method for preparing the meso-meso-bimodal porous alumina carrier according to claim 1, characterized in that, Includes the following steps: S1, Alumina, water, inorganic pore expander and / or organic pore expander are mixed and extruded to obtain an extruded strip; in the XRD pattern of the alumina, the relative intensity of the peak with 2θ of 13 to 16.6° is 100.0%, the relative intensity of the peak with 2θ of 16.6 to 23.2° is 85 to 88%, the peak with 2θ of 23.17 to 53.79° is a diffuse scattering peak, and the relative intensity of the peak with 2θ of 53.79 to 75° is 55 to 60%; S2, the extruded strip is matured, dried and calcined to obtain the carrier.

3. The method for preparing the meso-meso-bimodal porous alumina carrier according to claim 2, characterized in that, In the XRD pattern of the alumina, the characteristic peak angle of the peak with 2θ of 13–16.6° is 14–15°, the characteristic peak angle of the peak with 2θ of 16.6–23.2° is 19–20°, the peak with 2θ of 23.17–53.79° is a diffuse peak, and the characteristic peak angle of the peak with 2θ of 53.79–75° is 60.5–61.5°.

4. The method for preparing the meso-meso-bimodal porous alumina carrier according to claim 2, characterized in that, In the XRD pattern of the alumina after calcination at 800℃, the relative intensities of the peaks with 2θ values ​​of 14.69–23.74° are 54–58%, the relative intensities of the peaks with 2θ values ​​of 23.74–34.35° are 76–80%, the relative intensities of the peaks with 2θ values ​​of 34.35–39.04° are 100.0%, the relative intensities of the peaks with 2θ values ​​of 39.04–41.96° are 77–82%, the relative intensities of the peaks with 2θ values ​​of 41.96–52.52° are 62.5–68%, the relative intensities of the peaks with 2θ values ​​of 52.52–63.33° are 38.5–45%, and the relative intensities of the peaks with 2θ values ​​of 63.33–73.95° are 80.0–90%.

5. The method for preparing the meso-meso-bimodal porous alumina carrier according to claim 2, characterized in that, In the XRD pattern of the alumina after calcination at 800℃, the characteristic peak angles of the peaks with 2θ values ​​of 14.69–23.74° are 17.8–21.8°, the characteristic peak angles of the peaks with 2θ values ​​of 23.74–34.35° are 30.7–34.7°, the characteristic peak angles of the peaks with 2θ values ​​of 34.35–39.04° are 35.4–39.4°, the characteristic peak angles of the peaks with 2θ values ​​of 39.04–41.96° are 39.7–41.7°, the characteristic peak angles of the peaks with 2θ values ​​of 41.96–52.52° are 43.7–47.7°, the characteristic peak angles of the peaks with 2θ values ​​of 52.52–63.33° are 58.8–62.8°, and the characteristic peak angles of the peaks with 2θ values ​​of 63.33–73.95° are 65.1–69.1°.

6. The method for preparing the meso-meso-bimodal porous alumina carrier according to claim 2, characterized in that, It also includes step S3, in which the carrier is placed in a sealed high-pressure container and boiled under autogenous pressure, and then dried.

7. The method for preparing the meso-meso-bimodal porous alumina carrier according to claim 2, characterized in that, The inorganic pore-expanding agent is one or more of activated carbon, urea, ammonium carbonate, and ammonia water.

8. The method for preparing the meso-meso-bimodal porous alumina carrier according to claim 2, characterized in that, The organic pore expander is one or more of hydroxypropyl methylcellulose, starch, polyethylene glycol, polycarboxylic acid water-reducing agent, glycerin, carboxymethyl cellulose, and polyvinylpyrrolidone.

9. The method for preparing the meso-meso-bimodal porous alumina carrier according to claim 2, characterized in that, Based on 100% alumina mass, the inorganic pore expander is added at a rate of 1-20%, and the organic pore expander is added at a rate of 1-20%.

10. The method for preparing the meso-meso-bimodal porous alumina carrier according to claim 2, characterized in that, In step S2, the aging conditions are 20-35℃ for 24-72 hours; the drying temperature is 100-120℃; and the calcination conditions are 200-900℃ for 2-6 hours, with the preferred calcination temperature being 500-800℃.

11. The method for preparing the meso-meso-bimodal porous alumina carrier according to claim 6, characterized in that, In step S3, the boiling conditions are 120-200℃ for 1-6 hours, with a preferred boiling temperature of 130-180℃; the drying temperature is 100-120℃.

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