A dual-mesoporous distribution of γ-Al2O3 and its preparation method

Abstract

The present invention provides a γ-Al2O3 material with a dual-mesoporous distribution and a preparation method thereof, the method comprising the following steps: (1) providing a paste containing pseudo-boehmite, sesbania powder, acid and water; (2) extruding the paste in step (1), and starting to collect the material when the material extrusion pressure is ≥300N; (3) adding water to the extruded strip obtained in step (2), kneading, and obtaining a paste; (4) extruding the paste obtained in step (3); (5) pelletizing the extruded strip obtained in step (4), and calcining to obtain the γ-Al2O3 material. The present invention can adjust the pore size distribution by adjusting the formula and the extrusion process, and obtain a stable dual-pore carrier, and the dual-pore distribution is all within the mesoporous range.

Description

Technical Field

[0001] The present invention belongs to the field of mesoporous materials, and in particular relates to gamma-Al2O3 with a double-mesoporous distribution and a preparation method thereof. Background Art

[0002] Alumina bi-porous materials are a new type of porous material developed based on mesoporous materials. This material has two different pore sizes. The large pores allow larger molecules to enter and exit, serving as channels for the transport of substances and heat, with minimal diffusion resistance. The small pores, acting as reaction sites, provide a larger active area, improving the dispersion of active components and therefore holding great promise for future development.

[0003] Alumina catalysts with dual mesoporous channel distributions can precisely confine the size of reactants and products, which helps improve product selectivity. However, conventionally synthesized dual-porous γ-Al2O3 is generally partially mesoporous and partially macroporous (greater than 50nm). Since the mesopore range is very narrow (2-50nm), it is difficult for the commonly prepared dual-mesoporous pore size carriers to show a clear boundary. Currently, the most common method for preparing alumina dual-porous materials is to use two pseudo-boehmite dry gel powders with different pore size distributions to prepare alumina with a bimodal pore distribution. The resulting alumina has a very wide dual-pore range, which is not conducive to precise size control during the reaction process.

[0004] CN200710173515.1 introduces a method for preparing macroporous alumina with a double pore distribution. Alumina, a pore-forming agent, and solidified silicon are first mixed and ball-milled in a ball mill. The treated mixture is mixed and kneaded with an aqueous solution containing a cationic surfactant, an extrusion aid, and a peptizing agent to form a plastic body. The plastic body is then placed in a steam atmosphere for treatment. The obtained molded body is then dried and calcined to finally obtain an alumina carrier. Although this method can obtain a double pore distribution, the preparation method is relatively complicated.

[0005] CN93114901.0 introduces a method for preparing an alumina carrier with a double pore channel. The method mainly uses two aluminas with different pore size distributions as raw materials, and uses carbon black and surfactants as pore-forming agents to prepare alumina with a double pore distribution. This method has strict requirements on raw materials, and the amount of surfactant added is also relatively large. A large amount of additives is added, and the preparation cost is relatively high. In addition, about 4% of the macropores have a pore size of more than 100nm, which does not fall within the mesoporous range.

[0006] CN98114347.7 introduces a macroporous alumina carrier with a double-pore structure. The carrier is prepared by mixing one or more pseudo-boehmite dry glues prepared from different raw material routes with carbon black and a surfactant, and then undergoing peptization, molding, drying and calcination. However, the carrier has poor compressive strength. When used in fixed-bed, fluidized-bed or moving-bed reactors, the pulverization of the carrier may affect the performance and efficiency of the catalyst.

[0007] US4448896 proposes using carbon black as a pore-enlarging agent and forming it with pseudo-boehmite, followed by high-temperature calcination. During the calcination process, the pore-enlarging agent is oxidized, burned, and finally converted into gas to form a certain number of large pores. However, in this method, the pore-enlarging agent and pseudo-boehmite do not chemically react, so the pore distribution of the prepared carrier is diffuse and the mechanical strength is low. Summary of the Invention

[0008] The present invention aims to overcome the shortcomings of the prior art by providing a γ-Al2O3 carrier with a dual mesoporous distribution and a method for its preparation. Instead of using an organic aluminum source, the present invention utilizes a single raw material (pseudo-boehmite of a specific particle size) followed by the addition of a small amount of additives and a binder, resulting in a stable dual-mesoporous γ-Al2O3 carrier through a two-step process. Compared to prior art bimodal γ-Al2O3 carriers, the present invention eliminates the need for the addition of large amounts of pore-forming components such as carbon black and organic pore-enlarging agents. Instead, the pore size distribution can be adjusted through adjustments to the formulation and extrusion process, resulting in a stable dual-pore carrier with both pore distributions remaining within the mesoporous range.

[0009] Specifically, one aspect of the present invention provides a dual-mesoporous distribution of γ-Al2O3 material, wherein the pore size of the γ-Al2O3 material is bimodal, and the two most probable pore sizes of the γ-Al2O3 material are 5 to 10 nm and 10 to 25 nm, respectively.

[0010] In one or more embodiments, the two most probable pore sizes of the γ-Al 2 O 3 material are 7-9 nm and 10-20 nm, respectively.

[0011] In one or more embodiments, the pore volume of the γ-Al2O3 material is 0.5 to 1 cm 3 / g.

[0012] In one or more embodiments, the specific surface area of the γ-Al2O3 material is 190 to 220 m 2 / g.

[0013] In one or more embodiments, the average pore size of the γ-Al 2 O 3 material is 9.5 to 15 nm.

[0014] Another aspect of the present invention provides a method for preparing a dual-mesoporous distribution γ-Al2O3 material, the method comprising the following steps:

[0015] (1) providing a paste containing pseudo-boehmite, sesbania powder, acid and water;

[0016] (2) Extruding the paste in step (1) into strips, and collecting the material when the extrusion pressure of the material is ≥300N;

[0017] (3) adding water to the extruded strips obtained in step (2) and kneading to obtain a paste;

[0018] (4) extruding the paste obtained in step (3);

[0019] (5) pelletizing the extruded strips obtained in step (4) and calcining them to obtain the γ-Al2O3 material;

[0020] Wherein, step (3) and step (4) are performed once, or steps (3) and step (4) are performed multiple times in a cycle.

[0021] In one or more embodiments, in step (1), pseudo-boehmite and sesbania powder are first mixed uniformly, and then an acid-containing aqueous solution is added and kneaded to obtain the paste.

[0022] In one or more embodiments, in step (1), the pore volume of the pseudo-boehmite is 0.4 to 0.6 cm 3 / g.

[0023] In one or more embodiments, in step (1), the particle size of the pseudo-boehmite is 800-1000 mesh.

[0024] In one or more embodiments, in step (1), the mass of the sesbania powder is 2% to 3% of the mass of the pseudo-boehmite.

[0025] In one or more embodiments, in step (1), the acid is one or both selected from nitric acid and acetic acid.

[0026] In one or more embodiments, in step (1), the mass ratio of the acid to water in the paste is (0.5-2):100.

[0027] In one or more embodiments, in step (1), in the paste, the ratio of the total mass of the acid and water to the total mass of the pseudo-boehmite and sesbania powder is (0.72-0.85):1.

[0028] In one or more embodiments, in step (1), the kneading time is 10 to 15 minutes.

[0029] In one or more embodiments, in step (1), the paste further contains a pore former and / or a lubricant.

[0030] In one or more embodiments, the pore former is polyethylene glycol.

[0031] In one or more embodiments, in the paste, the mass of the pore former is 0.5% to 2% of the mass of the pseudo-boehmite.

[0032] In one or more embodiments, the lubricant is glycerin.

[0033] In one or more embodiments, in the paste, the mass of the lubricant is 0.5% to 2% of the mass of the pseudo-boehmite.

[0034] In one or more embodiments, in step (2), the material collection is started when the extrusion pressure of the material is 300-650N.

[0035] In one or more embodiments, in step (3), the mass of water added is 10% to 15% of the mass of the extruded strip.

[0036] In one or more embodiments, in step (3), the kneading time is 10 to 15 minutes.

[0037] In one or more embodiments, in step (5), the calcination temperature is 600-700° C., and the calcination time is 1.5-2.5 hours.

[0038] The present invention also provides a γ-Al2O3 material prepared by the method described in any embodiment of the present invention.

[0039] In one or more embodiments, the γ-Al2O3 material prepared by the method of the present invention is the γ-Al2O3 material described in any embodiment herein.

[0040] The present invention also provides a supported γ-Al2O3 material carrying a catalytically active component, wherein the supported γ-Al2O3 material comprises the γ-Al2O3 material described in any embodiment herein and a catalytically active component supported on the γ-Al2O3 material.

[0041] In one or more embodiments, the catalyst active component is a noble metal, for example, one or both selected from palladium and platinum.

[0042] The present invention also provides the use of the γ-Al2O3 material or the supported γ-Al2O3 material described in any embodiment of the present invention as a catalyst or catalyst support.

[0043] In one or more embodiments, the catalyst is a gas phase methyl chloride catalyst or a dehydrogenation catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the pore size distribution diagram of the γ-Al2O3 carrier of Example 6.

[0045] Figure 2 This is the pore size distribution diagram of the γ-Al2O3 carrier of Comparative Example 1. DETAILED DESCRIPTION

[0046] To facilitate understanding of the features and effects of the present invention by those skilled in the art, the following provides a general description and definition of the terms and expressions used in the specification and claims. Unless otherwise indicated, all technical and scientific terms used herein have the ordinary meanings as understood by those skilled in the art regarding the present invention. In the event of conflict, the definitions in this specification shall prevail.

[0047] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0048] Herein, “comprising,” “including,” “containing” and similar terms encompass the meanings of “consisting essentially of” and “consisting of,” for example, when “A comprises B and C” is disclosed herein, “A consists essentially of B and C” and “A consists of B and C” should be deemed to have been disclosed herein.

[0049] Herein, all features such as values, amounts, amounts, and concentrations defined in numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to include and specifically disclose all possible subranges and individual values within the range (including integers and fractions).

[0050] In this document, unless otherwise specified, percentage refers to mass percentage and ratio refers to mass ratio.

[0051] Herein, unless otherwise specified, the solvent of the solution is water. In the present invention, the water is preferably deionized water.

[0052] Herein, when describing embodiments or examples, it should be understood that they are not intended to limit the present invention to these embodiments or examples. On the contrary, all alternatives, modifications and equivalents of the methods and materials described herein are encompassed within the scope defined by the claims.

[0053] In this document, for the sake of brevity, not all possible combinations of the various technical features in each embodiment or example are described. Therefore, as long as there are no contradictions in the combination of these technical features, the various technical features in each embodiment or example can be combined in any way, and all possible combinations should be considered to be within the scope of this specification.

[0054] Herein, mesopores refer to pores with a pore diameter of 2-50 nm.

[0055] The present invention selects the pore volume 0.5m 3 In the extrusion molding process, a stable alumina catalyst with large pore volume and double mesoporous structure is obtained by two-step extrusion under a certain pressure.

[0056] In the present invention, during the first extrusion process, material collection is started when the pressure reaches greater than or equal to 300N. The present invention finds that when the first extrusion is carried out under low pressure (less than or equal to 100N), a double-pore structure will not be extruded. At least when the first extrusion is started at greater than or equal to 300N, a double-mesopore distribution will appear after the extrudate is kneaded twice and then extruded for the second time. The extrusion pressure can be regulated by adjusting the ratio of water to pseudo-boehmite and sesbania powder in the formula, but as the extrusion time increases, the screw extrusion pressure increases, and the sample pore structure obtained by the one-step method is unstable. The present invention can obtain a stable double-mesoporous structure alumina through two-step extrusion. In the present invention, the pressure during the second extrusion does not need to reach 300N, as long as the material is discharged under a stable state. For example, the pressure during the second extrusion can be around 80-90N.

[0057] The pore size of the dual-mesoporous distribution γ-Al2O3 material of the present invention is bimodal, and both most probable pore sizes are within the mesoporous range. Preferably, the two most probable pore sizes of the γ-Al2O3 material of the present invention are 5-10 nm and 10-25 nm, respectively. For example, the smaller most probable pore size of the γ-Al2O3 material of the present invention can be 6 nm, 7 nm, 8 nm, or 9 nm, and the larger most probable pore size can be 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 18 nm, 20 nm, or 23 nm.

[0058] The γ-Al2O3 material of the present invention has the characteristic of large pore volume, and the pore volume is preferably 0.5 to 1 cm 3 / g, for example 0.6cm 3 / g, 0.7cm 3 / g, 0.8cm 3 / g, 0.9cm 3 / g.

[0059] Preferably, the specific surface area of the γ-Al2O3 material of the present invention is 190 to 220 m 2 / g, for example 200m 2 / g, 210m 2 / g, and an average pore diameter of 9.5 to 15 nm, for example, 10 nm, 11 nm, 12 nm, 13 nm, or 14 nm.

[0060] The method for preparing a γ-Al2O3 material with a dual mesoporous distribution of the present invention is characterized in that the method comprises the following steps:

[0061] (1) providing a paste containing pseudo-boehmite, sesbania powder, acid and water;

[0062] (2) Extruding the paste in step (1) into strips, and collecting the material when the extrusion pressure of the material is ≥300N;

[0063] (3) adding water to the extruded strips obtained in step (2) and kneading to obtain a paste;

[0064] (4) extruding the paste obtained in step (3);

[0065] (5) pelletizing the extruded strips obtained in step (4) and calcining them to obtain the γ-Al2O3 material.

[0066] The pore volume of the pseudo-boehmite suitable for the present invention is preferably 0.4 to 0.6 cm 3 / g, for example 0.5cm 3 / g, and the particle size is preferably 800-1000 mesh.

[0067] In step (1), the mass of the sesbania powder is preferably 2% to 3% of the mass of the pseudo-boehmite, for example, 2.5%. The acid can be nitric acid and / or acetic acid. In the paste, the mass ratio of acid to water is preferably (0.5 to 2):100, for example, 0.9:100, 1:100, 1.5:100. The acid and water can be provided in the form of an acid-containing aqueous solution. The acid concentration of the acid-containing aqueous solution is preferably 0.5wt% to 2wt%, for example, 0.9wt%, 1wt%, 1.5wt%. In the present invention, the water-powder ratio (i.e., the ratio of the total mass of the acid and water to the total mass of the pseudo-boehmite and sesbania powder) is preferably (0.72 to 0.85):1, for example, 0.74:1, 0.75:1, 0.78:1, 0.8:1, 0.83:1. In some embodiments, the pseudo-boehmite and sesbania powder are first mixed uniformly, and then the acid-containing aqueous solution is added and kneaded to obtain the paste. The kneading time in step (1) is preferably 10 to 15 minutes.

[0068] In step (1), the paste may optionally contain a pore-forming agent and / or a lubricant. Suitable pore-forming agents for use in the present invention include polyethylene glycol. The mass of the pore-forming agent is preferably 0.5% to 2% of the mass of the pseudo-boehmite, for example, 1%. Suitable lubricants for use in the present invention include glycerol. The mass of the lubricant is preferably 0.5% to 2% of the mass of the pseudo-boehmite, for example, 1%.

[0069] In step (2), the material collection begins when the material extrusion pressure reaches ≥300N, for example, 300N, 400N, 500N, 550N, or 650N.

[0070] In step (3), the amount of water added is preferably 10%-15% of the mass of the extruded strip, such as 11%, 12%, 13%, or 14%. The kneading time in step (3) is preferably 10 to 15 minutes.

[0071] In the present invention, step (3) and step (4) may be performed only once, or may be performed twice or more than twice, for example, three times, four times, or five times. That is, after completing the kneading of step (3) and the extrusion of step (4) once, the pelletizing and roasting of step (5) may be performed directly, or the kneading of step (3) and the extrusion of step (4) may be performed one or more times before the pelletizing and roasting of step (5) are performed.

[0072] During the extrusion in step (4), the material can be discharged in a stable state, for example, the pressure can be around 80-90N.

[0073] The calcination temperature in step (5) is preferably 600-700°C, for example 650°C, and the calcination time is preferably 1.5-2.5 hours, for example 2 hours.

[0074] The dual-mesoporous distribution γ-Al2O3 material of the present invention has a small pore maximum diameter range of 5 to 10 nm, such as 6 nm, 7 nm, 8 nm, and 9 nm, and a large pore maximum diameter range of 10 to 25 nm, such as 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 18 nm, 20 nm, and 23 nm. The specific surface area of the dual-mesoporous distribution γ-Al2O3 material of the present invention can be 190 to 220 m 2 / g, for example 200m 2 / g, 210m 2 / g, and the average pore size can be 9.5 to 15 nm, such as 10 nm, 11 nm, 12 nm, 13 nm, or 14 nm. The dual-mesoporous γ-Al2O3 material of the present invention can be used as a catalyst or catalyst carrier for various known chemical reactions that can be carried out under the catalysis of γ-Al2O3 or supported γ-Al2O3 catalysts, exhibiting better catalytic performance. For example, the γ-Al2O3 material of the present invention can be directly used as a catalyst for the vapor phase methanol to methyl chloride reaction. The γ-Al2O3 material of the present invention can also be doped or coated with certain catalytically active ingredients, such as metal active materials, to obtain a supported γ-Al2O3 material. Useful metal active materials include precious metals, such as palladium and platinum. Supported γ-Al2O3 materials loaded with precious metals can be used as catalysts for dehydrogenation reactions, such as cyclopropane dehydrogenation. Therefore, the present invention also provides the use of γ-Al2O3 materials and supported γ-Al2O3 materials as catalysts or catalyst carriers.

[0075] Existing methods for preparing γ-Al2O3 with a bimodal pore distribution generally involve adding large amounts of pore-forming agents or directly combining two raw materials with different pore structures. Existing bimodal γ-Al2O3 catalysts require the addition of large amounts of pore-forming components such as carbon black and organic pore-enlarging agents. The addition of these additives significantly reduces catalyst strength, thereby impacting catalyst life. Compared to existing bimodal γ-Al2O3 carriers, the present invention eliminates the need for adding large amounts of pore-forming components such as carbon black and organic pore-enlarging agents. Instead, the pore size distribution can be adjusted simply by adjusting the formulation and extrusion process, resulting in a stable bimodal carrier with a bimodal pore distribution that remains within the mesoporous range.

[0076] The present invention will be described below by way of specific examples. It should be understood that these examples are merely illustrative and are not intended to limit the scope of the present invention. The methods, reagents, materials, and equipment used in the examples are, unless otherwise stated, conventional methods, reagents, materials, and equipment in the art. The starting compounds in the examples can all be purchased from commercial sources.

[0077] In the present invention, the method for measuring and calculating the pore size distribution, pore volume and specific surface area is as follows: using a Micromeritics ASAP 2460 pore size specific surface area meter from the United States, a certain mass of sample is weighed using a balance with a sensitivity of 0.0001g and placed in a sample tube, and treated at 300°C under vacuum conditions for a period of time to eliminate the original adsorbent on the solid surface, and then the treated sample is placed in a cold trap and tested with N2 as the adsorbent, and the pore size distribution curve and average pore size of the sample are calculated using the BJH model desorption curve, and the specific surface area of the sample is calculated using the BET equation.

[0078] Example 1

[0079] The pore volume is 0.5cm 3 / g, 200g of 800-1000 mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, and then 160g of 1% nitric acid solution is added and kneaded in a kneader for 10 minutes. The kneaded paste is placed in an extruder for extrusion. When the material extrusion pressure is equal to 300N, the material is collected and 10% (based on the wet material) of water is added to the collected material for re-kneading for 10 minutes. Finally, the kneaded paste is put back into the extruder and extruded once at 80-90N. The extruded strips are placed in a precision pelletizer for pelletizing and directly calcined at 650°C for 2 hours to obtain a large-pore volume double-mesoporous granular γ-Al2O3 catalyst.

[0080] Example 2

[0081] The pore volume is 0.5cm 3 / g, 200g of 800-1000 mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, and then 160g of 1.9% acetic acid solution is added and kneaded in a kneader for 10 minutes. The kneaded paste is placed in an extruder for extrusion. When the material extrusion pressure is equal to 300N, the material is collected and 12% (based on the wet material) of water is added to the collected material for re-kneading for 15 minutes. Finally, the kneaded paste is put back into the extruder and extruded once at 80-90N. The extruded strips are placed in a precision pelletizer for pelletizing and directly calcined at 650°C for 2 hours to obtain a large-pore volume double-mesoporous granular γ-Al2O3 catalyst.

[0082] Example 3

[0083] The pore volume is 0.5cm 3 / g, 200g of 800-1000 mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, then 170g of 1% nitric acid solution and 2g of glycerol are added, and the mixture is kneaded in a kneader for 10 minutes. The kneaded paste is placed in an extruder for extrusion. When the material extrusion pressure is equal to 300N, the material is collected, and 12% (based on the wet material) of water is added to the collected material for re-kneading for 15 minutes. Finally, the kneaded paste is put back into the extruder and extruded once at 80-90N. The extruded strips are placed in a precision pelletizer for pelletizing and directly calcined at 650°C for 2 hours to obtain a large-pore volume double-mesoporous granular γ-Al2O3 catalyst.

[0084] Example 4

[0085] The pore volume is 0.5cm 3 / g, 200g of 800-1000 mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, and then 160g of 1% nitric acid solution is added and kneaded in a kneader for 15 minutes. The kneaded paste is placed in an extruder for extrusion. When the material extrusion pressure is equal to 400N, the material is collected and 10% (based on the wet material) of water is added to the collected material for re-kneading for 10 minutes. Finally, the kneaded paste is put back into the extruder and extruded once at 80-90N. The extruded strips are placed in a precision pelletizer for pelletizing and directly calcined at 650°C for 2 hours to obtain a large-pore volume double-mesoporous granular γ-Al2O3 catalyst.

[0086] Example 5

[0087] The pore volume is 0.5cm 3 / g, 200g of 800-1000 mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, then 150g of 1% nitric acid solution and 2g of polyethylene glycol 10000 are added, and the mixture is kneaded in a kneader for 15 minutes. The kneaded paste is placed in an extruder for extrusion. When the material extrusion pressure is equal to 400N, the material is collected, and 12% (based on the wet material) of water is added to the collected material for re-kneading for 15 minutes. Finally, the kneaded paste is put back into the extruder and extruded once at 80-90N. The extruded strips are placed in a precision pelletizer for pelletizing and then directly calcined at 650°C for 2 hours to obtain a large-pore volume double-mesoporous granular γ-Al2O3 catalyst.

[0088] Example 6

[0089] The pore volume is 0.5cm 3 / g, 200g of 800-1000 mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, and then 160g of 1% nitric acid solution is added and kneaded in a kneader for 15 minutes. The kneaded paste is placed in an extruder for extrusion. When the material extrusion pressure is equal to 500N, the material is collected and 10% (based on the wet material) of water is added to the collected material for re-kneading for 10 minutes. Finally, the kneaded paste is put back into the extruder and extruded once at 80-90N. The extruded strips are placed in a precision pelletizer for pelletizing and then directly calcined at 650°C for 2 hours to obtain a large-pore volume double-mesoporous granular γ-Al2O3 catalyst.

[0090] Example 7

[0091] The pore volume is 0.5cm 3 / g, 200g of 800-1000 mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, and then a solution composed of 3g of 99% mass concentration acetic acid and 150g of deionized water is added, and the mixture is kneaded in a kneader for 15 minutes. The kneaded paste is placed in an extruder for extrusion. When the material extrusion pressure is equal to 550N, the material is collected, and 10% (based on the wet material) of water is added to the collected material for re-kneading for 10 minutes. Finally, the kneaded paste is put back into the extruder and extruded once at 80-90N. The extruded strip is placed in a precision pelletizer for pelletizing and then directly calcined at 650°C for 2 hours to obtain a large-pore volume double-mesoporous granular γ-Al2O3 catalyst.

[0092] Example 8

[0093] The pore volume is 0.5cm 3 / g, 200g of 800-1000 mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, and then a solution composed of 3g of 99% mass concentration acetic acid and 150g of deionized water is added, and the mixture is kneaded in a kneader for 15 minutes. The kneaded paste is placed in an extruder for extrusion. When the material extrusion pressure is equal to 650N, the material is collected, and 10% (based on the wet material) of water is added to the collected material for re-kneading for 10 minutes. Finally, the kneaded paste is put back into the extruder and extruded once at 80-90N. The extruded strip is placed in a precision pelletizer for pelletizing and directly calcined at 650°C for 2 hours to obtain a large-pore volume double-mesoporous granular γ-Al2O3 catalyst.

[0094] Comparative Example 1

[0095] The pore volume is 0.5cm 3 / g, 200g of 800-1000 mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, then 200g of 1% nitric acid solution is added, and the mixture is kneaded in a kneader for 10 minutes. The kneaded paste is placed in an extruder and extruded at an extrusion pressure of 70-80N. The extruded strips are placed in a precision pelletizer for pelletizing, dried at 80°C for 4 hours, and calcined at 650°C for 2 hours to obtain a granular γ-Al2O3 carrier.

[0096] Comparative Example 2

[0097] The pore volume is 0.5cm 3 / g, 200g of 800-1000 mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, then 160g of 1% nitric acid solution is added, and the mixture is kneaded in a kneader for 15 minutes. The kneaded paste is placed in an extruder for extrusion. When the extrusion pressure of the material is equal to 300N, the material is collected, and the extruded strips are placed in a precision pelletizer for pelletizing, dried at 80°C for 4 hours, and calcined at 650°C for 2 hours to obtain a granular γ-Al2O3 carrier.

[0098] Comparative Example 3

[0099] The pore volume is 0.5cm 3 / g, 200g of 800-1000mesh pseudo-boehmite and 5g of auxiliary agent sesbania powder are placed in a mixer and mixed evenly, and then 200g of 1% nitric acid solution is added and kneaded in a kneader for 10 minutes. The kneaded paste is placed in an extruder and extruded at an extrusion pressure of 80-90N. 10% (based on the wet material) of water is added to the received material and re-kneaded for 10 minutes. The material is re-extruded at an extrusion pressure of 80-90N, and 10% (based on the wet material) of water is added to the received material and re-kneaded for 10 minutes. The kneaded paste is placed in an extruder and extruded at 80-90N. The extruded material strips are placed in a precision pelletizer for pelletizing, dried at 80°C for 4 hours, and calcined at 650°C for 2 hours to obtain a granular γ-Al2O3 carrier.

[0100] Test Example 1

[0101] The specific surface area, pore volume and pore size distribution of the γ-Al2O3 carriers of the embodiment and the comparative example were tested. The results are shown in Table 1. Figure 1 and Figure 2 shown.

[0102] Table 1: Specific surface area, pore volume and pore size distribution of γ-Al2O3 support

[0103]

[0104]

[0105] From Table 1, Figure 1 、 Figure 2 It can be seen that the γ-Al2O3 carrier prepared by the method of the present invention has a dual-mesoporous structure, with the most probable pore diameter of the small pores ranging from 5 to 10 nm, the most probable pore diameter of the large pores ranging from 10 to 25 nm, and a pore volume of 0.5 to 1 cm 3 / g, with a specific surface area of 190 to 220 m 2 / g, and an average pore size of 9.5 to 15 nm. However, the pore size of the γ-Al2O3 carrier prepared by a method not according to the present invention is unimodal.

[0106] Test Example 2: Strength Test

[0107] The strength of the γ-Al2O3 carriers of the embodiment and the comparative example was tested using the DL3 intelligent particle strength tester of Dalian Penghui Technology Development Co., Ltd. according to the following method. The results are shown in Table 2:

[0108] 10 samples are randomly selected, and their lengths are measured first, followed by radial pressure. After the samples are crushed, the displayed P value is the radial compressive strength of the sample, in Newtons / cm.

[0109] Table 2: Length, radial pressure and radial compressive strength of γ-Al2O3 support

[0110] Length (cm) Pressure (N) Pressure (N / cm) Example 1 0.95 21.00 22.20 Example 2 1.02 19.70 19.40 Example 3 0.97 28.8 29.78 Example 4 0.96 22.60 23.54 Example 5 0.98 27.8 28.37 Example 6 0.95 21.30 22.42 Example 7 0.99 18.60 18.79 Example 8 0.99 19.10 19.20 Comparative Example 1 1.01 37.2 36.83

[0111] Test Example 3: Catalyst Performance Evaluation Experiment

[0112] The reaction of methanol to methyl chloride was carried out in a fixed-bed microreactor at atmospheric pressure. 5 ml of the γ-Al2O3 carrier of the embodiment or comparative example was loaded into a reaction tube as a catalyst, with the catalyst bed located in the constant temperature section of the heating furnace. HCl gas was introduced into the reactor using a mass flow meter, and methanol was introduced into the gasifier using a plunger pump and then gasified into the reactor. The reactor was heated to 300°C. After the temperature was constant, HCl and gaseous methanol were introduced into the reactor at a molar ratio of 1.1:1, and the reaction space velocity was 1000 h / min. -1 After 2 h of reaction, the tail gas was dried and passed into gas chromatography for online analysis. The results are shown in Table 3.

[0113] Table 3: Experimental results of catalytic performance of γ-Al2O3 carrier

[0114] Methanol conversion rate Methyl chloride selectivity Comparative Example 1 89.8 70.2 Example 1 99.3 87.8 Example 2 99.2 86.5 Example 3 99.1 89.5 Example 4 99.4 88.3 Example 5 99.5 87.7 Example 6 99.1 91.4

[0115] As can be seen from Table 3, the dual-mesoporous distribution γ-Al2O3 material of the present invention has better catalytic performance and can improve the reaction conversion rate and selectivity of methanol to methyl chloride.

Claims

1. A γ-Al2O3 material with dual mesoporous distribution, characterized in that: The pore size of the γ-Al2O3 material is bimodal, and the two most probable pore sizes of the γ-Al2O3 material are 5-10 nm and 10-25 nm, respectively. The specific surface area of the γ-Al2O3 material is 190-220 m 2 / g.

2. The γ-Al2O3 material according to claim 1, characterized in that The γ-Al2O3 material has one or more of the following characteristics: The two most probable pore sizes of the γ-Al2O3 material are 7-9 nm and 10-20 nm respectively; The pore volume of the γ-Al2O3 material is 0.5 to 1 cm 3 / g; The average pore diameter of the γ-Al2O3 material is 9.5-15 nm.

3. A method for preparing a dual-mesoporous distribution γ-Al2O3 material, characterized in that: The method comprises the following steps: (1) providing a paste containing pseudo-boehmite, sesbania powder, acid and water; (2) Extruding the paste in step (1) into strips, and collecting the material when the extrusion pressure of the material is ≥300N; (3) adding water to the extruded strips obtained in step (2) and kneading to obtain a paste; (4) extruding the paste obtained in step (3); (5) pelletizing the extruded strips obtained in step (4) and calcining them to obtain the γ-Al2O3 material; Wherein, step (3) and step (4) are performed once, or steps (3) and step (4) are performed multiple times in a cycle.

4. The method according to claim 3, wherein The method has one or more of the following characteristics: In step (1), pseudo-boehmite and sesbania powder are first mixed uniformly, and then an acid-containing aqueous solution is added and kneaded to obtain the paste; In step (1), the pore volume of the pseudo-boehmite is 0.4 to 0.6 cm 3 / g; In step (1), the particle size of the pseudo-boehmite is 800-1000 mesh; In step (1), the mass of the sesbania powder is 2% to 3% of the mass of the pseudo-boehmite; In step (1), the acid is one or both selected from nitric acid and acetic acid; In step (1), the mass ratio of the acid to water in the paste is (0.5-2):100; In step (1), in the paste, the ratio of the total mass of the acid and water to the total mass of the pseudo-boehmite and sesbania powder is (0.72-0.85):1; In step (1), the kneading time is 10 to 15 minutes; In step (1), the paste further contains a pore-forming agent and / or a lubricant.

5. The method according to claim 4, wherein The method has one or more of the following characteristics: The pore-forming agent is polyethylene glycol; The mass of the pore-forming agent is 0.5% to 2% of the mass of the pseudo-boehmite; The lubricant is glycerin; The mass of the lubricant is 0.5% to 2% of the mass of the pseudo-boehmite.

6. The method according to claim 3, wherein In step (2), the material collection begins when the material extrusion pressure reaches 300-650N.

7. The method according to claim 3, wherein In step (3), the mass of the added water is 10% to 15% of the mass of the extruded strip.

8. The method according to claim 3, wherein In step (3), the kneading time is 10 to 15 minutes.

9. The method according to claim 3, wherein In step (5), the calcination temperature is 600-700° C., and the calcination time is 1.5-2.5 hours.

10. γ-Al2O3 material prepared by the method according to any one of claims 3 to 9.

11. The γ-Al2O3 material according to claim 10, characterized in that The γ-Al2O3 material is as described in claim 1 or 2.

12. A supported γ-Al2O3 material supporting a catalytically active component, characterized in that: The supported γ-Al2O3 material comprises the γ-Al2O3 material according to claim 1, 2, 10 or 11 and a catalyst active component supported on the γ-Al2O3 material.

13. The supported γ-Al2O3 material according to claim 12, characterized in that: The active component of the catalyst is a precious metal.

14. The supported γ-Al2O3 material according to claim 13, characterized in that The noble metal is one or two selected from palladium and platinum.

15. Use of the γ-Al2O3 material according to claim 1, 2, 10 or 11 or the supported γ-Al2O3 material according to any one of claims 12 to 14 as a catalyst or catalyst support.

16. The use according to claim 15, characterized in that The catalyst is a gas phase method for preparing monochloromethane catalyst or a dehydrogenation reaction catalyst.

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