A toluene shape-selective disproportionation catalyst, a preparation method and application thereof

Abstract

This invention discloses a toluene shape-selective disproportionation catalyst, its preparation method, and its application. The toluene shape-selective disproportionation catalyst contains a modified ZSM-5 molecular sieve supported on alkaline earth metals and macroporous alumina. Its total acidity is 0.15–0.25 mmol / g, the acidity outside the micropores is no higher than 5.0 μmol / g, preferably 0.5–3.0 μmol / g, and the pore volume is 0.18–0.30 cm³. 3 / g, wherein the micropore volume is 0.05~0.12cm³. 3 Based on the weight of the toluene shape-selective disproportionation catalyst, the modified ZSM-5 molecular sieve has a mass content of 40-95% and the alkaline earth metal content is 0.5-1.5%. The catalyst preparation method includes the preparation of modified ZSM-5 molecular sieves supported on alkaline earth metals and the preparation process of catalysts containing modified ZSM-5 molecular sieves supported on alkaline earth metals. The catalyst preparation process is simple, reducing the acidity of the catalyst surface without affecting the pore flow of the catalyst, improving xylene selectivity while significantly reducing side reactions such as aromatic condensation, reducing carbon deposition, and increasing catalyst lifespan.

Description

Technical Field

[0001] This invention belongs to the field of toluene disproportionation, and relates to a toluene shape-selective disproportionation catalyst, its preparation method and application, specifically to a highly active and stable toluene shape-selective disproportionation catalyst, its preparation method and application. Background Technology

[0002] Traditional toluene disproportionation and alkyl transfer processes are controlled by thermodynamic equilibrium. The typical composition of the three xylene isomers (p, m, and ortho) is PX:MX:OX = 24:54:22 (molar). m-Xylene has a higher content than PX, requiring adsorption separation and C8 aromatic isomerization to increase PX production. This process is lengthy, involves large material recycling volumes, and has high material and energy consumption. Toluene shape-selective disproportionation technology, however, exhibits high para-selectivity, generating high levels of p-xylene, thus effectively reducing the cost of p-xylene separation.

[0003] CN105013522B provides a toluene shape-selective disproportionation catalyst, its preparation method and uses, and chemical liquid-phase deposition modification of the acid-modified catalyst matrix, which can improve the accessibility of the molecular sieve active center while masking the acidity of the outer surface.

[0004] CN200910025152.6 discloses a method for preparing a shape-selective disproportionation Silicalite-1 molecular sieve membrane catalyst for toluene. The method involves adding a ZSM-5 molded support molecular sieve into a crystallization solution composed of a silicon source, a template agent, deionized water, and anhydrous ethanol for two in-situ hydrothermal crystallizations. Finally, the catalyst is exchanged multiple times with an ammonium salt solution, dried, and calcined to obtain the Silicalite-1 molecular sieve membrane catalyst.

[0005] CN200610029951.7 discloses a catalyst for the shape-selective disproportionation reaction of toluene to produce p-xylene. It employs ZSM-5 molecular sieve as the main active component, uses titanium dioxide as an inert binder, and modifies the catalyst surface with an inert silica coating. The total pore volume of the catalyst is 0.27–0.45 mL / g, with mesopores ≥2 nm accounting for 55–75% of the total pore volume. The mesopores ≥2 nm are mainly provided by the binder, and the binder and silica coating contents are relatively high. The implementation of the silica coating is complex.

[0006] In existing technologies, the acidic structure of ZSM-5 is modulated by chemical deposition, generation of pure silicon molecular sieve membranes, and silicon dioxide coatings to improve the selectivity of the catalyst. However, there are problems such as pore blockage during acid modification, the need for large amounts of organic solvents, and complex operation. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a toluene shape-selective disproportionation catalyst, its preparation method, and its applications. The catalyst preparation process is simple, reducing the acidity of the catalyst's outer surface without affecting the pore flow of the catalyst. It improves xylene selectivity while significantly reducing side reactions such as aromatic hydrocarbon condensation, reducing carbon deposition, and extending catalyst lifespan.

[0008] A toluene shape-selective disproportionation catalyst, comprising a modified ZSM-5 molecular sieve supported on alkaline earth metals and macroporous alumina, having a total acidity of 0.15–0.25 mmol / g, an acidity outside the micropores not exceeding 5.0 μmol / g, preferably 0.5–3.0 μmol / g, and a pore volume of 0.18–0.30 cm³. 3 / g, wherein the micropore volume is 0.05~0.12cm³. 3 / g, based on the weight of the toluene shape-selective disproportionation catalyst, the modified ZSM-5 molecular sieve has a mass content of 40~95% and an alkaline earth metal mass content of 0.5~1.5%.

[0009] Further, preferably, the total acid content of the toluene shape-selective disproportionation catalyst is 0.17~0.22 mmol / g, and the acid content outside the micropores is not higher than 3.0 μmol / g, preferably 0.3~2.0 μmol / g.

[0010] Further, preferably, the pore volume of the toluene shape-selective disproportionation catalyst is 0.20~0.25 cm³. 3 / g, wherein the micropore volume is 0.06~0.09cm³. 3 / g.

[0011] Further, preferably, the alkaline earth metal content of the toluene shape-selective disproportionation catalyst is 0.8-1.2% based on the weight of the toluene shape-selective disproportionation catalyst.

[0012] Furthermore, based on the weight of the toluene shape-selective disproportionation catalyst, the mass content of modified ZSM-5 molecular sieve in the toluene shape-selective disproportionation catalyst is 60-90%, and the mass content of macroporous alumina is 5-37%.

[0013] A method for preparing a toluene shape-selective disproportionation catalyst includes the preparation of a modified ZSM-5 molecular sieve supported on an alkaline earth metal and the preparation process of a catalyst containing a modified ZSM-5 molecular sieve supported on an alkaline earth metal. The preparation method of the modified ZSM-5 molecular sieve supported on an alkaline earth metal includes the following steps:

[0014] (1) Hydrothermal treatment of hydrogen-type ZSM-5 molecular sieve;

[0015] (2) The material obtained in step (1) is impregnated with a channel protection liquid;

[0016] (3) The material obtained in step (2) is treated with a sterically hindered organic acid;

[0017] (4) Mix the material obtained in step (3) with the dealuminizing and silicon replenishing reagent to perform dealuminizing and silicon replenishment;

[0018] (5) Modify the material obtained in step (4) with alkaline earth metals.

[0019] Further, in step (1), the ZSM-5 molecular sieve can be a commercially available product or a microporous hydrogen-form ZSM-5 molecular sieve prepared according to existing technology. The properties of the ZSM-5 molecular sieve are as follows: SiO2 / Al2O3 molar ratio 15~30, specific surface area 300~450m². 2 / g, pore volume 0.15~0.20cm³ 3 / g.

[0020] Further, in step (1), the specific treatment process in the hydrothermal process is as follows: place the commercially available ZSM-5 molecular sieve in a hydrothermal furnace, introduce steam, and treat it for 1h to 3h at a temperature of 250℃~400℃ and a pressure of 0.05~0.2MPa.

[0021] Further, in step (2), the pore protection solution is one or more of isopropylamine solution, tetraethylammonium hydroxide solution, tetrapropylammonium hydroxide solution, etc. The concentration of the pore protection solution is 0.8~2.0 mol / L, preferably 1.1~1.5 mol / L.

[0022] Furthermore, in step (2), the impregnation is preferably an equal-volume impregnation. The impregnation treatment temperature is room temperature, generally 20~25℃.

[0023] Further, in step (3), the sterically hindered organic acid is one or more of 2,4-dimethylbenzenesulfonic acid and 2,5-dimethylbenzoic acid.

[0024] Further, in step (3), the specific operation is as follows: first, the material obtained in step (2) is mixed with water, wherein the liquid-solid volume ratio of water to the material obtained in step (2) is 2:1 to 6:1, and then organic acid is added until the pH value of the solution drops to 7.0 to 5.0, preferably 5.5 to 6.5.

[0025] Further, in step (4), the dealuminizing and silicon-replenishing reagent is at least one of ammonium hexafluorosilicate solution, tetraethyl orthosilicate solution, etc. The molar concentration of the dealuminizing and silicon-replenishing reagent is 0.3~1.0 mol / L. The mass ratio of the material obtained in step (4) to the dealuminizing and silicon-replenishing solution is 1:1~1:5. The mixing temperature is 60~100℃.

[0026] Further, the specific operation process of step (4) is as follows: rapidly heat the material obtained in step (3) to 60~100℃ and continuously stir, add the aluminum removal and silicon replenishment reagent dropwise, and continue stirring for 60~120min after the dropwise addition is completed. Among them, the dropwise addition rate does not exceed 0.5mL / min·g of the material obtained in step (3); preferably 0.2~0.4mL / min·g of the material obtained in step (3).

[0027] Furthermore, in step (4), the material needs to be washed, filtered, dried and roasted. The filtration and washing can be carried out using conventional methods in the art. The drying temperature is 100℃~150℃ and the drying time is 2~4h. The roasting temperature is 400℃~600℃ and the roasting time is 3~5h.

[0028] Furthermore, the alkaline earth metals mentioned in step (5) refer to Group IIA metals such as beryllium, magnesium, calcium, strontium, and barium, with magnesium and calcium being preferred.

[0029] Further, the alkaline earth metal modification mentioned in step (5) refers to impregnating the material obtained in step (4) with an alkaline earth metal solution, such as Ca(OAc)2 or Mg(OAc)2. The mass concentration of alkaline earth metal in the alkaline earth metal solution is 3.0~10.0%, preferably 5.0~8.0%. The impregnation process can be equal volume impregnation.

[0030] In the method of the present invention, the preparation process of the modified ZSM-5 molecular sieve catalyst containing supported alkaline earth metal is as follows: the modified ZSM-5 molecular sieve containing supported alkaline earth metal is mixed with macroporous alumina and a binder, extruded, shaped, dried and calcined to obtain a toluene shape disproportionation catalyst.

[0031] This invention also provides an application of the catalyst in the shape-selective disproportionation of toluene, wherein the operating conditions are as follows: reaction temperature 400~500℃, pressure 0.5~3.0 MPa, and weight liquid hourly space velocity (WHSV) 2.0~5.0 h⁻¹. -1 .

[0032] Compared with existing technologies, the toluene shape-selective disproportionation catalyst, its preparation method, and its application have the following advantages:

[0033] (1) The process of shape-selective disproportionation of toluene to form PX is affected by both acid catalysis and diffusion control. Toluene reacts in the ZSM-5 molecular sieve with modified outer surface. To obtain high para-selectivity, appropriate molecular sieve pore size and passivation of the outer surface are crucial. The passivated outer surface of the molecular sieve can prevent the outward diffusion of p-xylene from undergoing secondary isomerization at the acidic sites on the outer surface, which is beneficial to maintaining the existing para-selectivity. By adjusting the size of the crystal channels of HZSM-5 molecular sieve to be similar to the molecular dynamic diameter of the benzene ring, the diffusion coefficients of benzene, toluene, and p-xylene in the ZSM-5 molecular sieve pores are much greater than those of ortho-xylene and meta-xylene. This allows only smaller molecules such as benzene, toluene, and p-xylene to freely enter and exit, and the concentration of p-xylene in the mixed xylene products is much higher than the thermodynamic equilibrium concentration.

[0034] (2) The present invention shrinks the ZSM-5 molecular sieve cell through hydrothermal treatment, reduces its micropore size, strengthens the restriction of the pores on the highly sterically hindered ortho-xylene and meta-xylene, and destroys part of the silicon-aluminum structure to form a certain amount of mesopores, which enhances the diffusion of reactant molecules and improves their activity. Then, the selective removal of acidity at the molecular sieve pore opening and outer surface is achieved through dealumination and silicon replenishment under the protection of micropores, which inhibits the xylene isomerization reaction with a reaction rate much higher than the disproportionation reaction. At the same time, it does not deposit in the catalyst pores, which is conducive to the diffusion of reactant molecules, reduces the possibility of large molecule aggregation and carbon deposition, and improves the catalyst lifetime. The introduction of alkaline earth metals further reduces the molecular sieve pore size and improves the selectivity of the catalyst for p-xylene. Implementation

[0035] The following examples and comparative examples further illustrate the role and effect of the technical solution of the present invention, but the following examples do not constitute a limitation on the scope of protection of the present invention.

[0036] In this invention, unless otherwise specified, all percentages (%) in the embodiments and comparative examples refer to mass fractions.

[0037] In this invention, the infrared determination method for pyridine is as follows: The powdered catalyst is compressed into tablets, evacuated, and then degassed at 450°C for 2 hours. After the temperature drops to room temperature, a pyridine molecule with a kinetic diameter of 5 Å is used as a probe molecule to measure the infrared spectrum of chemical desorption, and the adsorption amount is calculated. Since the diameter of the pyridine molecule is smaller than that of the molecular sieve pores, this method can obtain its total acid content.

[0038] In this invention, the total infrared acidity of di-tert-butylpyridine refers to the proton acid that a 2,6-di-tert-butylpyridine molecule with a kinetic diameter of 10.5 Å can contact. The infrared determination method for 2,6-di-tert-butylpyridine is as follows: The powdered catalyst is compressed into tablets, vacuumed, and degassed at 450°C for 2 hours. After the temperature drops to room temperature, 2,6-di-tert-butylpyridine molecules are used as probe molecules to measure their infrared spectrum of chemical desorption, and the adsorption amount is calculated. Since the diameter of 2,6-di-tert-butylpyridine molecules is larger than the micropores of the molecular sieve, this method can obtain the acidity outside the micropores.

[0039] In the method of this invention, the pore volume and micropore volume are determined by the following method: An ASAP 2420 cryogenic liquid nitrogen physical adsorption instrument manufactured by Micrometics, USA is used. Before measurement, the sample is first calcined at 550℃ for 4 hours to remove the template agent. During testing, the sample is pretreated at 300℃ for 3 hours, and then nitrogen gas is adsorbed at 77K for testing.

[0040] The ZSM-5 raw powder involved in the embodiments and comparative examples of this invention is a commercially available product, which is a microporous hydrogen-form ZSM-5 molecular sieve. The properties of the ZSM-5 are as follows: specific surface area is 305 m² / g. 2 / g, pore volume is 0.201cm³ 3 / g, water absorption rate is 57%, SiO2 / Al2O3 ratio (molar) is 20.2.

[0041] Example 1

[0042] 300g of commercially available ZSM-5 raw powder was placed in a hydrothermal treatment furnace and treated at 250℃ and 0.05MPa pressure for 1h. The resulting material was impregnated with 165mL of 2.0 mol / L isopropylamine solution and allowed to stand for 10 min. 1700mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH value was 7.0. The mixture was stirred and heated to 60℃. 300mL of 0.3mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2mL / min·g using a peristaltic pump. The temperature was maintained at 60℃ and the mixture was stirred continuously for 90 min. Hot filtration was performed, and 3000 mL of water was added to the filter cake. The mixture was heated to 60°C and maintained for 20 min, then hot filtration was performed again. The filter cake was dried at 120°C for 24 h and then calcined at 500°C for 3 h. The resulting material was impregnated with an equal volume of 3.0% Ca(OAc)₂ solution. After drying and calcination, modified ZSM-5 molecular sieve ZT-1 was obtained. 270 g of ZT-1 sample and 24 g of macroporous alumina were crushed and mixed evenly. An appropriate amount of binder was added to obtain an extrudable material, which was then extruded, dried, and calcined to obtain toluene shape-selective disproportionation catalyst CAT-1. Its properties are as follows: total acidity 0.248 mmol / g, external acidity 0.005 mmol / g, and pore volume 0.184 cm³. 3 / g, of which the micropore volume is 0.118 cm³. 3 / g, with an alkaline earth metal content of 0.5%.

[0043] Example 2

[0044] 300g of commercially available ZSM-5 raw powder was placed in a hydrothermal treatment furnace and treated at 400℃ and 0.2MPa pressure for 1h. The resulting material was impregnated with 165mL of 0.8 mol / L isopropylamine solution and allowed to stand for 10 min. 1700mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH value was 7.0. The mixture was stirred and heated to 60℃. 300mL of 1.0 mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2mL / min·g using a peristaltic pump. The temperature was maintained at 60℃ and the mixture was stirred continuously for 90 min. Hot filtration was performed, and 3000 mL of water was added to the filter cake. The mixture was heated to 60°C and maintained for 20 min, then hot filtration was performed again. The filter cake was dried at 120°C for 24 h and then calcined at 500°C for 3 h. The resulting material was impregnated with an equal volume of a 10.0% Ca(OAc)₂ solution. After drying and calcination, the modified ZSM-5 molecular sieve ZT-2 was obtained. 240 g of ZT-2 sample and 54 g of macroporous alumina were crushed and mixed evenly. An appropriate amount of binder was added to obtain an extrudable material, which was then extruded, dried, and calcined to obtain the toluene shape-selective disproportionation catalyst CAT-2. Its properties are as follows: total acidity 0.155 mmol / g, external acidity 0.005 mmol / g, and pore volume 0.29 cm³. 3 / g, of which the micropore volume is 0.053 cm³ 3 / g.

[0045] Example 3

[0046] 300g of commercially available ZSM-5 raw powder was placed in a hydrothermal treatment furnace and treated at 300℃ and 0.1MPa pressure for 1h. The resulting material was impregnated with 165mL of 1.2mol / L isopropylamine solution and allowed to stand for 10 min. 1700mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH value was 6.0. The mixture was stirred and heated to 60℃. 300mL of 0.5mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2mL / min·g using a peristaltic pump. The temperature was maintained at 60℃ and the mixture was stirred continuously for 90 min. Hot filtration was performed, and 3000 mL of water was added to the filter cake. The mixture was heated to 60°C and maintained for 20 min, then hot filtration was performed again. The filter cake was dried at 120°C for 24 h and then calcined at 500°C for 3 h. The resulting material was impregnated with an equal volume of 7.0% Ca(OAc)₂ solution. After drying and calcination, modified ZSM-5 molecular sieve ZT-3 was obtained. 260 g of ZT-3 sample and 34 g of macroporous alumina were crushed and mixed evenly. An appropriate amount of binder was added to obtain an extrudable material, which was then extruded, dried, and calcined to obtain toluene shape-selective disproportionation catalyst CAT-3. Its properties are as follows: total acidity 0.206 mmol / g, external acidity 0.002 mmol / g, and pore volume 0.23 cm³.3 / g, of which the micropore volume is 0.086 cm³. 3 / g, with an alkaline earth metal content of 0.5%.

[0047] Example 4

[0048] 300g of commercially available ZSM-5 raw powder was placed in a hydrothermal treatment furnace and treated at 350℃ and 0.1MPa pressure for 1h. The resulting material was impregnated with 165mL of 1.2mol / L isopropylamine solution and allowed to stand for 10 min. 1700mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH value was 5.5. The mixture was stirred and heated to 60℃. 300mL of 0.5mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2mL / min·g using a peristaltic pump. The temperature was maintained at 60℃ and the mixture was stirred continuously for 90 min. Hot filtration was performed, and 3000 mL of water was added to the filter cake. The mixture was heated to 60°C and maintained for 20 min, then hot filtration was performed again. The filter cake was dried at 120°C for 24 h and then calcined at 500°C for 3 h. The resulting material was impregnated with an equal volume of 7.0% Ca(OAc)₂ solution. After drying and calcination, the modified ZSM-5 molecular sieve ZT-4 was obtained. 260 g of ZT-4 sample and 34 g of macroporous alumina were crushed and mixed evenly. An appropriate amount of binder was added to obtain an extrudable material, which was then extruded, dried, and calcined to obtain the toluene shape-selective disproportionation catalyst CAT-4. Its properties are as follows: total acidity 0.184 mmol / g, external acidity 0.0016 mmol / g, and pore volume 0.22 cm³. 3 / g, of which the micropore volume is 0.081 cm³. 3 / g, with an alkaline earth metal content of 0.8%.

[0049] Example 5

[0050] 300g of commercially available ZSM-5 raw powder was placed in a hydrothermal treatment furnace and treated at 350℃ and 0.1MPa pressure for 1h. The resulting material was impregnated with 165mL of 1.5mol / L isopropylamine solution and allowed to stand for 10 min. 1700mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH value was 6.5. The mixture was stirred and heated to 60℃. 300mL of 0.5mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2mL / min·g using a peristaltic pump. The temperature was maintained at 60℃ and the mixture was stirred continuously for 90 min. Hot filtration was performed, and 3000 mL of water was added to the filter cake. The mixture was heated to 60°C and maintained for 20 min, then hot filtration was performed again. The filter cake was dried at 120°C for 24 h and then calcined at 500°C for 3 h. The resulting material was impregnated with an equal volume of 7.0% Ca(OAc)₂ solution. After drying and calcination, the modified ZSM-5 molecular sieve ZT-5 was obtained. 270 g of ZT-5 sample and 24 g of macroporous alumina were crushed and mixed evenly. An appropriate amount of binder was added to obtain an extrudable material, which was then extruded, dried, and calcined to obtain the toluene shape-selective disproportionation catalyst CAT-5. Its properties are as follows: total acidity 0.195 mmol / g, external acidity 0.0020 mmol / g, and pore volume 0.23 cm³. 3 / g, of which the micropore volume is 0.090 cm³. 3 / g.

[0051] Example 6

[0052] 300g of commercially available ZSM-5 raw powder was placed in a hydrothermal treatment furnace and treated at 350℃ and 0.2MPa pressure for 1h. The resulting material was impregnated with 165mL of 1.5mol / L isopropylamine solution and allowed to stand for 10 min. 1700mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH value was 6.0. The mixture was stirred and heated to 60℃. 300mL of 0.5mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2mL / min·g using a peristaltic pump. The temperature was maintained at 60℃ and the mixture was stirred continuously for 90 min. Hot filtration was performed, and 3000 mL of water was added to the filter cake. The mixture was heated to 60°C and maintained for 20 min, then hot filtration was performed again. The filter cake was dried at 120°C for 24 h and then calcined at 500°C for 3 h. The resulting material was impregnated with an equal volume of 7.0% Ca(OAc)₂ solution. After drying and calcination, modified ZSM-5 molecular sieve ZT-6 was obtained. 250 g of ZT-6 sample and 44 g of macroporous alumina were crushed and mixed evenly. An appropriate amount of binder was added to obtain an extrudable material, which was then extruded, dried, and calcined to obtain toluene shape-selective disproportionation catalyst CAT-6. Its properties are as follows: total acidity 0.171 mmol / g, external acidity 0.0018 mmol / g, and pore volume 0.21 cm³.3 / g, of which the micropore volume is 0.088 cm³. 3 / g.

[0053] Example 7

[0054] 300g of commercially available ZSM-5 raw powder was placed in a hydrothermal treatment furnace and treated at 400℃ and 0.2MPa pressure for 1h. The resulting material was impregnated with 165mL of 1.5mol / L isopropylamine solution and allowed to stand for 10 min. 1700mL of water was added, and 2,5-dibenzenesulfonic acid was added dropwise until the pH value was 5.5. The mixture was stirred and heated to 60℃. 300mL of 0.5mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2mL / min·g using a peristaltic pump. The temperature was maintained at 60℃ and the mixture was stirred continuously for 90 min. Hot filtration was performed, and 3000 mL of water was added to the filter cake. The mixture was heated to 60°C and maintained for 20 min, then hot filtration was performed again. The filter cake was dried at 120°C for 24 h and then calcined at 500°C for 3 h. The resulting material was impregnated with an equal volume of 7.0% Ca(OAc)₂ solution. After drying and calcination, modified ZSM-5 molecular sieve ZT-7 was obtained. 250 g of ZT-7 sample and 44 g of macroporous alumina were crushed and mixed evenly. An appropriate amount of binder was added to obtain an extrudable material, which was then extruded, dried, and calcined to obtain toluene shape-selective disproportionation catalyst CAT-6. Its properties are as follows: total acidity 0.171 mmol / g, external acidity 0.0015 mmol / g, and pore volume 0.20 cm³. 3 / g, of which the micropore volume is 0.068 cm³. 3 / g.

[0055] Comparative Example 1

[0056] 300g of commercially available ZSM-5 raw powder was impregnated with 165mL of 0.6 mol / L isopropylamine solution, allowed to stand for 10 min, then 170mL of water was added, and 2,4-xylenecarboxylic acid was added dropwise until the pH reached 6.0. The mixture was stirred and heated to 65℃, and 300mL of 0.6 mol / L ammonium hexafluorosilicate solution was added dropwise at a rate of 0.2mL / min·g using a peristaltic pump. The temperature was maintained at 65℃ and stirring was continued for 90 min. The mixture was filtered while hot, and 300mL of water was added to the resulting filter cake. The mixture was heated to 60℃ and maintained for 20 min, then filtered while hot. The filter cake was dried at 120℃ for 24 h and then calcined at 500℃ for 3 h. The resulting material was impregnated with 7.0% Ca(OAc)2 solution, and then dried and calcined to obtain modified ZSM-5 molecular sieve ZT-B1. 250g of ZT-B1 sample and 44g of macroporous alumina were mixed evenly by crushing. An appropriate amount of binder was added to obtain an extrudable material. This material was then extruded, dried, and calcined to obtain the toluene shape-selective disproportionation catalyst CAT-B1. Its properties are as follows: total acidity 0.40 mmol / g, external acidity 0.0018 mmol / g, and pore volume 0.21 cm³. 3 / g, of which the micropore volume is 0.14 cm³. 3 / g.

[0057] Comparative Example 2

[0058] 300g of commercially available ZSM-5 raw powder was placed in a hydrothermal treatment furnace and treated at 350℃ and 0.1MPa pressure for 1 hour. The resulting material was impregnated with an equal volume of 7.0% Ca(OAc)2 solution. The resulting material was then dried and calcined to obtain modified ZSM-5 molecular sieve ZT-B2. 250g of ZT-B2 sample and 44g of macroporous alumina were taken, crushed and mixed evenly, and an appropriate amount of binder was added to obtain an extrudable material. This material was then extruded, dried, and calcined to obtain toluene shape-selective disproportionation catalyst CAT-B2. Its properties are as follows: total acidity 0.185 mmol / g, external acidity 0.091 mmol / g, and pore volume 0.21 cm³. 3 / g, of which the micropore volume is 0.085 cm³. 3 / g, with an alkaline earth metal content of 0.8%.

[0059] Example 8

[0060] 10 g of catalyst CAT1 was taken and reacted at a reaction temperature of 440 °C, a pressure of 1.2 MPa, and a WHSV of 3.0 h⁻¹. -1 When the hydrogen-to-hydrocarbon molar ratio is 2.0, a toluene disproportionation experiment was conducted for 160 h, and the toluene conversion rate was 34.5 wt%, the selectivity for p-xylene was 92.1 wt%, and the coke deposition was 1.3 wt%.

[0061] Example 9

[0062] 10 g of catalyst CAT2 was taken and reacted at a reaction temperature of 440 °C, a pressure of 1.2 MPa, and a WHSV of 3.0 h⁻¹. -1 When the hydrogen-to-hydrocarbon molar ratio is 2.0, a toluene disproportionation experiment was conducted for 160 h, and the toluene conversion rate was 32.5 wt%, the selectivity for p-xylene was 91.5 wt%, and the coke deposition was 0.9 wt%.

[0063] Example 10

[0064] 10 g of catalyst CAT3 was taken and reacted at a reaction temperature of 440 °C, a pressure of 1.2 MPa, and a liquid hourly space velocity (WHSV) of 3.0 h⁻¹. -1 When the hydrogen-to-hydrocarbon molar ratio is 2.0, a toluene disproportionation experiment was conducted for 160 h, and the toluene conversion rate was 37.0 wt%, the selectivity for p-xylene was 97.5 wt%, and the coke deposition was 0.4 wt%.

[0065] Comparative Example 3

[0066] 10 g of catalyst CAT-B1 was taken and reacted at a reaction temperature of 440 °C, a pressure of 1.2 MPa, and a liquid hourly space velocity (WHSV) of 3.0 h⁻¹. -1 When the hydrogen-to-hydrocarbon molar ratio is 2.0, a toluene disproportionation experiment was conducted for 160 h, and the toluene conversion rate was 29.0 wt%, the selectivity for p-xylene was 87.5 wt%, and the coke deposition was 2.1 wt%.

[0067] Comparative Example 4

[0068] 10 g of catalyst CAT-B2 was taken and reacted at a reaction temperature of 440 °C, a pressure of 1.2 MPa, and a WHSV of 3.0 h⁻¹. -1 When the hydrogen-to-hydrocarbon molar ratio is 2.0, a toluene disproportionation experiment was conducted for 160 h, and the toluene conversion rate was 27.2 wt%, the selectivity for p-xylene was 89.8 wt%, and the coke deposition was 1.8 wt%.

Claims

1. A toluene shape-selective disproportionation catalyst, characterized in that: The toluene shape-selective disproportionation catalyst contains modified ZSM-5 molecular sieves supported on alkaline earth metals and macroporous alumina. Its total acidity is 0.15–0.25 mmol / g, the acidity outside the micropores is no higher than 5.0 μmol / g, and the pore volume is 0.18–0.30 cm³. 3 / g, wherein the micropore volume is 0.05~0.12cm³. 3 / g, based on the weight of the toluene shape-selective disproportionation catalyst, the mass content of the modified ZSM-5 molecular sieve is 40~95%, and the mass content of alkaline earth metal is 0.5~1.5%; the preparation method of the catalyst includes: preparation of modified ZSM-5 molecular sieve loaded with alkaline earth metal and preparation process of modified ZSM-5 molecular sieve catalyst containing loaded alkaline earth metal, wherein the preparation method of modified ZSM-5 molecular sieve loaded with alkaline earth metal includes the following steps: (1) hydrothermal treatment of hydrogen-type ZSM-5 molecular sieve; (2) The material obtained in step (1) is impregnated with a pore protection solution; the pore protection solution is one or more of isopropylamine solution, tetraethylammonium hydroxide solution, and tetrapropylammonium hydroxide solution; (3) The material obtained in step (2) is treated with a sterically hindered organic acid; (4) Mix the material obtained in step (3) with the dealuminizing and silicon replenishing reagent to perform dealuminizing and silicon replenishment; (5) Modify the material obtained in step (4) with alkaline earth metals.

2. The catalyst according to claim 1, characterized in that, The amount of acid outside the micropores of the toluene shape-selective disproportionation catalyst is 0.5~3.0 μmol / g.

3. The catalyst according to claim 1, characterized in that: The total acid content of the toluene shape-selective disproportionation catalyst is 0.17~0.22 mmol / g, and the acid content outside the micropores is 0.3~2.0 μmol / g.

4. The catalyst according to claim 1, characterized in that: The toluene shape-selective disproportionation catalyst has a pore volume of 0.20~0.25 cm³. 3 / g, wherein the micropore volume is 0.06~0.09cm³. 3 / g.

5. The catalyst according to claim 1, characterized in that: Based on the weight of the toluene shape-selective disproportionation catalyst, the alkaline earth metal content of the toluene shape-selective disproportionation catalyst is 0.8~1.2%.

6. The catalyst according to claim 1, characterized in that: Based on the weight of the toluene shape-selective disproportionation catalyst, the mass content of modified ZSM-5 molecular sieve in the toluene shape-selective disproportionation catalyst is 60-90%, and the mass content of macroporous alumina is 5-37%.

7. A method for preparing a toluene shape-selective disproportionation catalyst according to any one of claims 1-6, characterized in that: The present invention includes the preparation process of modified ZSM-5 molecular sieves supported on alkaline earth metals and the preparation process of catalysts containing modified ZSM-5 molecular sieves supported on alkaline earth metals. The preparation method of modified ZSM-5 molecular sieves supported on alkaline earth metals includes the following steps: (1) Hydrothermal treatment of hydrogen-type ZSM-5 molecular sieve; (2) The material obtained in step (1) is impregnated with a pore protection liquid, wherein the concentration of the pore protection liquid is 0.8~2.0 mol / L; (3) The material obtained in step (2) is treated with a sterically hindered organic acid. The specific operation is as follows: First, mix the material obtained in step (2) with water, and then add a sterically hindered organic acid until the pH value of the solution drops to 7.0~5.

0. (4) Mix the material obtained in step (3) with the dealuminizing and silicon replenishing reagent for dealuminizing and silicon replenishing. The dropping rate of the dealuminizing and silicon replenishing reagent shall not exceed 0.5 mL / min·g of the material obtained in step (3). (5) Modify the material obtained in step (4) with alkaline earth metals.

8. The method according to claim 7, characterized in that: In step (1), the properties of the hydrogen-form ZSM-5 molecular sieve are as follows: SiO2 / Al2O3 molar ratio 15~30, specific surface area 300~450m². 2 / g, pore volume 0.15~0.20cm³ 3 / g.

9. The method according to claim 7, characterized in that: In step (1), the specific process of the hydrothermal treatment is as follows: place the commercially available hydrogen-type ZSM-5 molecular sieve in a hydrothermal furnace, introduce steam, and treat for 1h to 3h at a temperature of 250℃~400℃ and a pressure of 0.05~0.2MPa.

10. The method according to claim 7, characterized in that: In step (2), the concentration of the pore protection liquid is 1.1~1.5 mol / L.

11. The method according to claim 7, characterized in that: The sterically hindered organic acid is 2,4-dimethylbenzenesulfonic acid and / or 2,5-dimethylbenzoic acid.

12. The method according to claim 7, characterized in that: In step (3), The liquid-to-solid volume ratio of water to the material obtained in step (2) is 2:1 to 6:1; and / or Add a sterically hindered organic acid until the pH of the solution drops to 5.5-6.

5.

13. The method according to claim 7, characterized in that: In step (4), the dealuminizing and silicon replenishing reagent is at least one of ammonium hexafluorosilicate solution and tetraethyl orthosilicate solution, the molar concentration of the dealuminizing and silicon replenishing reagent is 0.3~1.0 mol / L, the mass ratio of the material obtained in step (3) to the dealuminizing and silicon replenishing solution is 1:1~1:5, and the mixing temperature is 60~100℃.

14. The method according to claim 7, characterized in that: The specific operation process of step (4) is as follows: rapidly heat the material obtained in step (3) to 60~100℃ and continuously stir, add aluminum removal and silicon replenishment reagent dropwise, and continue stirring for 60~120min after the dropwise addition is completed; wherein, the dropwise addition rate is 0.2~0.4mL / min·g of the material obtained in step (3).

15. The method according to claim 7, characterized in that: In step (4), after aluminum removal and silicon replenishment, the resulting material is washed, filtered, dried and calcined. The drying temperature is 100℃~150℃ and the drying time is 2~4h. The calcination temperature is 400℃~600℃ and the calcination time is 3~5h.

16. The method according to claim 7, characterized in that: The alkaline earth metal mentioned in step (5) is at least one of beryllium, magnesium, calcium, strontium, and barium.

17. The method according to claim 16, characterized in that, The alkaline earth metal mentioned in step (5) is magnesium or calcium.

18. The method according to claim 7, characterized in that: The alkaline earth metal modification mentioned in step (5) refers to impregnating the material obtained in step (4) with an alkaline earth metal solution, wherein the mass concentration of alkaline earth metal in the alkaline earth metal solution is 3.0~10.0%.

19. The method according to claim 18, characterized in that: The alkaline earth metal solution has a mass concentration of 5.0-8.0%.

20. The method according to claim 7, characterized in that: The preparation process of the modified ZSM-5 molecular sieve catalyst containing supported alkaline earth metal is as follows: the modified ZSM-5 molecular sieve with supported alkaline earth metal is mixed with macroporous alumina and binder, extruded, shaped, dried and calcined to obtain the toluene shape disproportionation catalyst.

21. The application of the toluene shape-selective disproportionation catalyst according to any one of claims 1-6 in the shape-selective disproportionation of toluene, wherein the application operating conditions are as follows: reaction temperature 400~500℃, pressure 0.5~3.0 MPa, and weight liquid hourly space velocity (WHSV) 2.0~5.0 h⁻¹. -1 .