Modification method of molecular sieve catalyst and application of molecular sieve catalyst in polychlorobenzene isomerization

Abstract

The invention relates to the field of catalysts, in particular to a modification method of a molecular sieve catalyst and application of the molecular sieve catalyst in polychlorobenzene isomerization, and the modification method of the molecular sieve catalyst comprises the following steps: (1) carrying out dealumination on the molecular sieve catalyst, and then carrying out first washing and drying treatment; (2) dispersing the catalyst obtained in the step (1) in a metal salt aqueous solution, adding an alkali solution to adjust the pH value of the system to 8-11 for aging, and then carrying out second washing and drying treatment, the mass ratio of the metal salt to the catalyst to water being (0.01-0.15): 1: (4-40), and the mass of the metal salt being metered by the metal amount; (3) dipping the catalyst obtained in the step (2) in an organic sulfonic acid or salt solution thereof, separating, and then carrying out third washing and drying treatment; and (4) roasting the catalyst obtained in the step (3) to obtain the modified molecular sieve catalyst.

Description

Technical Field

[0001] The present invention relates to the field of catalysts, in particular to a method for modifying a molecular sieve catalyst and application of the modified molecular sieve catalyst in the isomerization of polychlorinated benzenes. Background Art

[0002] Meta-dichlorobenzene, an intermediate in the synthesis of dyes, fungicides, and herbicides, is widely used in the pharmaceutical and pesticide industries. However, in the benzene chlorination process, because chlorine acts as a directing group at the ortho and para positions, the product is typically a mixture of ortho-, para-, and meta-dichlorobenzene isomers. This process produces large amounts of ortho- and para-dichlorobenzene as byproducts, along with a small amount of trichlorobenzene. On the other hand, among the three trichlorobenzene isomers, 1,3,5-trichlorobenzene is an important organic chemical raw material used in organic synthesis, pesticides, and dye synthesis. It is also widely used as a solvent in the production of pesticides, dyes, pharmaceuticals, electrolytes, lubricants, and other products, making it a high-value-added chemical intermediate. Therefore, to address the problem of a high number of low-value-added products in existing chlorination technologies, it is of great significance to develop processes for the transposition of dichlorobenzene to produce meta-dichlorobenzene and the transposition of trichlorobenzene to produce 1,3,5-trichlorobenzene.

[0003] At present, the industry uses o-dichlorobenzene or p-dichlorobenzene as raw materials, and uses anhydrous aluminum chloride to catalyze the isomerization reaction of dichlorobenzene to realize the synthesis of meta-dichlorobenzene. However, after the reaction is completed, the catalyst needs to be removed by hydrolysis, which will produce a large amount of acidic wastewater containing chloride ions, and the treatment cost is high, which is not conducive to mass production. Patent CN112047805A reports on the use of sulfonate-supported solid acid catalysts based on this, and uses p-dichlorobenzene as a raw material to prepare a method for meta-dichlorobenzene. The m-dichlorobenzene yield of this method at 300 ° C is 81.9%, which can be recycled 6 times, and the problem that the isomerization system catalyst cannot be recovered is initially explored. In addition, patent CN103708994A discloses another approach to prepare meta-dichlorobenzene, which uses nano ZSM-5 molecular sieves, nano ZSM-5 molecular sieves modified by acid dealumination, or nano ZSM-5 molecular sieves modified by alkali desiliconization as catalysts, and reacts by a fixed bed to cause p-dichlorobenzene to undergo isomerization reaction. This method is carried out at 450℃, system pressure 3MPa, and space velocity 1h -1 The conversion rate was 55.8% and the selectivity was 88.2%, but the catalyst pores were easily clogged, which led to catalyst deactivation.

[0004] Based on the above research, acidic molecular sieves, as environmentally friendly solid acid catalysts, can replace aluminum chloride in the isomerization of o- and p-dichlorobenzene. Their unique properties allow for continuous operation under fixed-bed conditions, but activity stability remains an issue. Therefore, there is an urgent need to develop a method for modifying molecular sieve catalysts that achieves both stability and high selectivity, enabling long-term, continuous operation of polychlorobenzene isomerization reactions. Summary of the Invention

[0005] A first aspect of the present invention provides a method for modifying a molecular sieve catalyst, the method comprising the following steps:

[0006] (1) Dealumination of the molecular sieve catalyst followed by a first washing and drying process;

[0007] (2) dispersing the catalyst obtained in step (1) in a metal salt aqueous solution, and adding an alkaline solution to adjust the pH of the system to 8-11 for aging, followed by a second washing and drying treatment, wherein the mass ratio of the metal salt, the catalyst, and water is 0.01-0.15:1:4-40, wherein the mass of the metal salt is calculated as the amount of metal;

[0008] (3) immersing the catalyst obtained in step (2) in an organic sulfonic acid or its salt solution, separating and then performing a third washing and drying treatment;

[0009] (4) calcining the catalyst obtained in step (3) to obtain a modified molecular sieve catalyst.

[0010] In one embodiment of the present invention, the dealumination in step (1) is carried out as follows: the molecular sieve is dispersed in water under a protective atmosphere at a temperature of 150-310° C. to carry out water-soluble dealumination.

[0011] In one embodiment of the present invention, the molecular sieve is a ZSM-5 molecular sieve having a silicon-aluminum ratio of ≥30 and a specific surface area of ​​≥250 m 2 / g, mesh size 15-80 mesh.

[0012] In one embodiment of the present invention, the dispersed solid-liquid ratio of the molecular sieve and water is 1:10-50, by mass.

[0013] In one embodiment of the present invention, the protective gas comprises at least one gas selected from the group consisting of nitrogen, argon, helium and carbon dioxide, the protective gas pressure is 1-10 MPa, and the water dissolution time is 2-12 h.

[0014] In one embodiment of the present application, the metal ion in the metal salt in step (2) comprises a rare earth metal ion, preferably one or more of Zr, La, Ce, Pr, and Nd, and the acid radical ion comprises one or more of nitrate, acetate, sulfate, phosphate, and chloride, preferably nitrate and / or chloride.

[0015] In one embodiment of the present application, the base solution in step (2) comprises an ammonium hydroxide solution and / or ammonia water.

[0016] In one embodiment of the present application, the aging temperature in step (2) is 140-200℃, and the time is 12-48h.

[0017] In one embodiment of the present application, in step (3), the organic sulfonic acid comprises at least one small molecule sulfonic acid selected from the group consisting of methyl sulfonic acid, ethyl sulfonic acid, and 1-propyl sulfonic acid.

[0018] In one embodiment of the present application, the concentration of the organic sulfonic acid or its salt solution is 0.5-2.5%.

[0019] In one embodiment of the present application, the mass ratio of the catalyst obtained in step (2) to the organic sulfonic acid or its salt solution is 1:10 to 1:40.

[0020] In one embodiment of the present application, the washing is performed using water, and the washing is performed until the pH is neutral.

[0021] In one embodiment of the present application, the first drying temperature is 40-120℃, and the first drying time is 6-72h.

[0022] In one embodiment of the present application, the second drying temperature is 80-120℃, and the second drying time is 6-24h.

[0023] In one embodiment of the present application, the third drying temperature is 80-120℃, and the third drying time is 6-24h.

[0024] In one embodiment of the present application, the calcination temperature is 100-200℃, and the calcination time is 8-36h.

[0025] The second aspect of the present application provides a modified molecular sieve catalyst prepared by the method of the present application.

[0026] The third aspect of the present application provides a method for isomerization of a halogenated aromatic compound, wherein the method uses the modified molecular sieve catalyst of the present application.

[0027] In one embodiment of the present invention, the halogenated aromatic compound is a chlorinated aromatic compound, preferably comprising at least one compound selected from the group consisting of 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene and 1,2,4-trichlorobenzene.

[0028] A fourth aspect of the present invention provides an isomerized product prepared according to the isomerization reaction method described herein. DETAILED DESCRIPTION

[0029] The inventors of the present application discovered that by subjecting the molecular sieve catalyst to water-soluble dealumination modification, new solid acid sites were reconstructed, thereby achieving a long-term continuous isomerization reaction of dichlorobenzene and even trichlorobenzene compounds, and completed the present invention on this basis.

[0030] " Scope " disclosed herein is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a scope with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for a particular parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range " ab " represents the abbreviation of any real number combination between a and b, wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0031] In this application, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0032] In this application, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0033] In the present application, unless otherwise specified, all the steps mentioned herein can be carried out in sequence or randomly, but preferably in sequence. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method mentioned herein can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0034] In the present application, unless otherwise specified, "including" and "comprising" mentioned herein are open-ended and can also be closed. For example, "including" and "comprising" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0035] In the description herein, it is to be noted that, unless otherwise specified, "above", "below" include the number itself, and "one or more" means two or more.

[0036] In the description herein, unless otherwise specified, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any one of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0037] In the present application, unless otherwise specified, the percentage (%) or the part refers to the percentage by weight or the weight part of the composition.

[0038] In the present application, unless otherwise specified, the sum of the contents of the components in the composition is 100%.

[0039] In the present application, unless otherwise specified, the sum of the parts of the components in the composition can be 100 parts by weight.

[0040] In the present application, unless otherwise specified, "combination thereof" means a multi-component mixture of the elements, such as two, three, four, and up to the maximum possible multi-component mixture.

[0041] Unless otherwise specified, the term "one" used in the present application means "at least one".

[0042] In the present application, unless otherwise specified, each reaction is carried out at room temperature and atmospheric pressure.

[0043] The first aspect of the present application provides a method for modifying a molecular sieve catalyst, the method comprising the following steps:

[0044] (1) Dealumination of the molecular sieve catalyst followed by a first washing and drying process;

[0045] (2) dispersing the catalyst obtained in step (1) in a metal salt aqueous solution, and adding an alkaline solution to adjust the pH of the system to 8-11 for aging, followed by a second washing and drying treatment, wherein the mass ratio of the metal salt, the catalyst, and water is 0.01-0.15:1:4-40, wherein the mass of the metal salt is calculated as the amount of metal;

[0046] (3) immersing the catalyst obtained in step (2) in an organic sulfonic acid or its salt solution, separating and then performing a third washing and drying treatment;

[0047] (4) calcining the catalyst obtained in step (3) to obtain a modified molecular sieve catalyst.

[0048] The protective gas comprises at least one gas selected from the group consisting of nitrogen, argon, helium and carbon dioxide, the protective gas pressure is 1-10 MPa, and the water dissolution time is 2-12 hours.

[0049] In the present invention, the molecular sieve catalyst is a ZSM series molecular sieve, such as ZSM-5, ZSM-22, ZSM-23, ZSM-35, preferably ZSM-5 molecular sieve. ZSM-5 molecular sieve is an environmentally friendly solid acid catalyst with a large external specific surface area, a high intracrystalline diffusion rate and a pore structure. It can be used to catalyze the isomerization of dichlorobenzene or trichlorobenzene to prepare meta-dichlorobenzene or 1,3,5-trichlorobenzene. ZSM-5 molecular sieve has a very high silicon-to-aluminum ratio, and its silicon-to-aluminum ratio can vary in a wide range of 10 to 3000 or more. In one embodiment of the present invention, the molecular sieve has a silicon-to-aluminum ratio of ≥30, preferably ≥40, and a specific surface area of ​​≥250 m 2 / g, preferably ≥300 m 2 / g, mesh size is 15-80 mesh, preferably 20-60 mesh.

[0050] The method of the present application can be used to modify ZSM series molecular sieves. The ZSM series molecular sieve catalyst can be a commercial ZSM series molecular sieve available on the market, or a ZSM series molecular sieve prepared by a known method.

[0051] In the present invention, at least some Al atoms in the molecular sieve framework are selectively removed by dealumination, thereby forming a mesoporous structure rich in Si-OH defects while maintaining the integrity of the pore structure. This dealumination step can be performed using methods such as acid dealumination, steam dealumination, and high-temperature aqueous dealumination. There are no particular restrictions on the specific method of dealumination of the molecular sieve, as long as it does not excessively damage the pore structure.

[0052] In one embodiment of the present invention, the step of molecular sieve dealumination is carried out as follows: under a protective atmosphere and a temperature of 150-310°C, preferably 200-275°C, the molecular sieve is dispersed in water for water-soluble dealumination. The water-soluble dealumination can be carried out under stirring. The water can be ultrapure water, deionized water, etc., preferably ultrapure water. The dispersed solid-liquid ratio of the molecular sieve and water is 1:10-50, by mass. There is no particular restriction on the type of protective atmosphere, which can be an inert gas, nitrogen, etc. Preferably, the protective gas includes at least one gas selected from the group consisting of nitrogen, argon, helium and carbon dioxide. The pressure of the protective gas is 1-10 MPa, and the water dissolution time is 2-12 hours.

[0053] In step (1), after the dealumination is completed, the molecular sieve is subjected to a first washing and drying. There are no particular restrictions on the washing and drying conditions. In one embodiment of the present invention, water is used for washing, the first drying temperature is 40-120°C, and the drying time is 6-72 hours.

[0054] In step (2), the catalyst obtained in step (1) is dispersed in a metal salt solution. The metal ions in the metal salt include rare earth metal ions, preferably one or more of Zr, La, Ce, Pr, and Nd, and the acid ions include one or more of nitrate, acetate, sulfate, phosphate, and hydrochloride, preferably nitrate and / or hydrochloride. The mass ratio of the metal salt (metal amount), catalyst, and water is 0.01-0.15:1:4-40, preferably 0.02-0.1:1:6-40, more preferably 0.05-0.1:1:10-40, and more preferably 0.05-0.1:1:20-40. The rare earth metal is deposited at the dealuminated vacancy by in-situ coordination to form a rare earth-silanol composite Lewis acid center. An alkaline solution is then added to adjust the pH of the system to 8-11 for aging. The alkaline solution includes ammonium hydroxide solution and / or aqueous ammonia. Aging is performed at a temperature of 140-200°C, preferably 160-180°C, for 12-48 hours, preferably 24-59 hours. A second washing and drying process is then performed. The washing and drying conditions are not particularly limited. In one embodiment of the present invention, water is used for washing until the solution pH reaches approximately neutral. The second drying temperature is 80-120°C, and the drying time is 6-24 hours.

[0055] In step (3), the catalyst obtained in step (2) is immersed in an organic sulfonic acid or its salt solution. The organic sulfonic acid is an organic small molecule sulfonic acid, including but not limited to alkylsulfonic acid, benzenesulfonic acid, halogenated sulfonic acid, etc. The organic sulfonates that can be used include but are not limited to sodium methanesulfonate, sodium ethanesulfonate, etc. In one embodiment of the present invention, the organic sulfonic acid includes at least one small molecule sulfonic acid selected from the group consisting of methylsulfonic acid, ethylsulfonic acid, and 1-propylsulfonic acid. The concentration of the organic sulfonic acid or its salt solution is 0.5-3%, preferably 0.75-2.75%, more preferably 1-2.5%. The mass ratio of the catalyst obtained in step (2) to the organic sulfonic acid or its salt solution is 1:5 to 1:40, preferably 1:10-1:30, more preferably 1:10-1:20. The immersion time can be 6-24 hours. The catalyst having a rare earth-silanol composite Lewis acid center obtained in step (2) is immersed in an organic sulfonic acid or its salt solution for sulfonic acid functionalization modification, so that -SO3⁻ coordination grafting occurs on the rare earth metal surface, forming a rare earth-sulfonic acid dual-active interface with electronic modulation function. After the sulfonic acid functionalization modification is completed, the molecular sieve catalyst is separated and subjected to a third washing and drying treatment. There are no special restrictions on the washing and drying conditions. In one embodiment of the present invention, water is used for washing until the solution pH reaches approximately neutral, the third drying temperature is 80-120°C, and the drying time is 6-24 hours.

[0056] In step (4), the catalyst obtained in step (3) is calcined. In the present application, the specific means and methods of catalyst calcination are not particularly limited, as long as the purpose of the present application can be achieved. In a specific embodiment of the present application, the calcination is carried out in an inert gas, and the inert gas includes one of N2, He, Ne and Ar. In the present application, "calcination" can adopt a conventional calcination temperature in the art. In one embodiment of the present invention, the calcination temperature is 100-200°C and the calcination time is 8-36h.

[0057] In the present application, there is no particular limitation on the specific means and methods for separating, washing, and drying the catalyst, provided that the purpose of the present application is achieved. The drying step may be carried out under an inert gas atmosphere or by vacuum drying. The solvent used for washing includes one or more of water, methanol, ethanol, isopropanol, and acetonitrile, with water being preferred.

[0058] In one embodiment of the present application, the amount of the washing solvent used in step (2) is 4-40 times the amount of the catalyst by weight.

[0059] In a specific embodiment of the present application, the temperature rise process during the calcination stage can be a single-gradient temperature rise or a dual-gradient temperature rise. The single-gradient temperature rise program includes heating to the calcination temperature at a heating rate of 0.2-1.0°C / min; the dual-gradient temperature rise program includes heating to a gradient temperature of 200-300°C at a heating rate of 0.5-2°C / min, holding for 2-12 hours, and then heating to the calcination temperature at a heating rate of 4-10°C / min.

[0060] The molecular sieve catalyst prepared by the method described in the present application has high catalytic activity and improved stability in the isomerization reaction of chlorinated aromatic compounds, and can prepare isomerized products with high selectivity.

[0061] Another aspect of the present application provides a method for isomerization of halogenated aromatic compounds, wherein the method uses the modified molecular sieve catalyst of the present invention to carry out the reaction.

[0062] In this application, the term "halogenated aromatic compound" refers to a compound in which a functional group in an aromatic compound is replaced by a halogen atom, such as fluorine, chlorine, bromine, or iodine. Halogenated organic compounds include, but are not limited to, chloroaromatic hydrocarbons and bromoaromatic hydrocarbons. Halogenated organic compounds preferably include polychlorinated aromatic hydrocarbons. In a specific embodiment of this application, the halogenated aromatic compound includes one or more of 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,4-trichlorobenzene.

[0063] In the present application, the isomerization reaction can be carried out in a fixed bed reactor, the reaction temperature can be 300-400°C, and the catalyst mass space velocity is 0.05-0.5h -1 , the pressure is 0.5-2MPa, the protective gas is an inert gas, and the molar ratio of the inert gas to the reactant is 50-100.

[0064] Another aspect of the present invention provides an isomerized product prepared according to the isomerization reaction method described herein.

[0065] Taking 1,2-dichlorobenzene and 1,4-dichlorobenzene as examples, the chlorine at the 1,2- and 1,4-positions undergo catalytic isomerization to produce 1,3-dichlorobenzene, an important intermediate needed in industry. Taking 1,2,3-trichlorobenzene and 1,2,4-trichlorobenzene as examples, the chlorine at the 1,2,3- and 1,2,3-positions undergo catalytic isomerization to produce 1,3,5-trichlorobenzene, also a high-value-added chemical intermediate needed in industry. The modified molecular sieve catalyst obtained in this application can improve the selectivity of 1,3-dichlorobenzene and 1,3,5-trichlorobenzene and can achieve long-term continuous isomerization reactions.

[0066] The advantages of the present invention are:

[0067] 1. This invention innovatively adopts a step-by-step topological modification strategy. First, the Al atoms in the molecular sieve framework are selectively removed by vapor phase dealumination, thereby forming a mesoporous structure rich in Si-OH defects while ensuring the integrity of the pore structure.

[0068] 2. By in situ coordination deposition, a second metal species (such as Ce³+) is anchored at the dealuminated vacancies to construct a rare earth-silanol composite Lewis acid center. Sulfonic acid functionalization is then used to enable -SO⁻ coordination grafting on the rare earth metal surface, forming a rare earth-sulfonic acid dual-active interface with electronic modulation capabilities. The strong Lewis acid sites formed by the rare earth metal and the framework oxygen polarize the C-Cl bonds in the polychlorinated benzene molecules. The moderately strong Brønsted acid sites generated by the coordination of the sulfonic acid group and the rare earth further promote the protonation and deprotonation of Cl⁻.

[0069] 3. The present invention can realize the long-term continuous isomerization reaction of dichlorobenzene and trichlorobenzene under solvent-free conditions, and there is no obvious activity reduction after running for 500 hours.

[0070] Unless otherwise specified, all raw materials used in this application can be obtained commercially or prepared according to conventional methods in the art. Unless otherwise defined or specified, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the methods of the present invention. Other aspects of the present invention will be apparent to those skilled in the art from the disclosure herein.

[0071] Example

[0072] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the invention. The experimental methods for the following examples, for which specific conditions are not specified, are generally measured according to national standards. If there is no corresponding national standard, the methods are carried out according to general international standards, conventional conditions, or according to the conditions recommended by the manufacturer. Unless otherwise stated, all parts are by weight, all percentages are by weight, and the polymer molecular weight is the number average molecular weight.

[0073] Raw material source and preparation

[0074] Main experimental reagents

[0075] Reagents Type or purity Manufacturer ZSM-5 molecular sieve NKF-5 Tianjin Nanhua Catalyst Co., Ltd. ZSM-22 molecular sieve NKF-22 Tianjin Nanhua Catalyst Co., Ltd. ZSM-23 molecular sieve NKF-23 Tianjin Nanhua Catalyst Co., Ltd. ZSM-35 molecular sieve NKF-15 Tianjin Nanhua Catalyst Co., Ltd. <![CDATA[ZrO(NO3)2]]> 99% Sinopharm Chemical Reagent Co., Ltd. <![CDATA[Zr(NO3)4]]> AR Sinopharm Chemical Reagent Co., Ltd. [ZrCl4] 98% Sinopharm Chemical Reagent Co., Ltd. <![CDATA[LaCl3]]> AR Sinopharm Chemical Reagent Co., Ltd. Ce(NO3)3 99.5% Sinopharm Chemical Reagent Co., Ltd. <![CDATA[NdCl3]]> 99.9% Sinopharm Chemical Reagent Co., Ltd. [PrCl3] 99.9% Sinopharm Chemical Reagent Co., Ltd. Ammonium hydroxide solution 25%~28% Sinopharm Chemical Reagent Co., Ltd. Methanesulfonic acid 95% Sigma-Aldrich Ethylsulfonic acid 95% Sigma-Aldrich Propylsulfonic acid 95% Sigma-Aldrich 1,2-Dichlorobenzene AR Sinopharm Chemical Reagent Co., Ltd. 1,4-Dichlorobenzene AR Sinopharm Chemical Reagent Co., Ltd. 1,2,3-Trichlorobenzene AR Sinopharm Chemical Reagent Co., Ltd. 1,2,4-Trichlorobenzene AR Sinopharm Chemical Reagent Co., Ltd. Ar 99.999% Yangzhou Chunhui Gas Co., Ltd. <![CDATA[N2]]> 99.999% Yangzhou Chunhui Gas Co., Ltd. He 99.999% Yangzhou Chunhui Gas Co., Ltd. <![CDATA[CO2]]> 99.999% Yangzhou Chunhui Gas Co., Ltd. Ultrapure water -- self made

[0076] Main experimental instruments

[0077] Instrument name model Manufacturer electronic balance JA31002 Shanghai Yitian Scientific Instrument Co., Ltd. Fixed bed reactor HF-V1 Shanghai Baikal Technology Group Co., Ltd. Gas chromatograph 7890A Agilent Technologies Autoclave BKLS-1L Shanghai Baikal Technology Group Co., Ltd.

[0078] Gas chromatography test conditions

[0079]

[0080] Calculation method of conversion rate and selectivity: Collect the liquid after reaction, analyze the components by gas chromatography, use hydrogen flame detector (FID), and calculate the concentration of each component by external standard method, where

[0081] Conversion rate (%) = 1-(substrate concentration after reaction / substrate concentration before reaction) × 100%,

[0082] Selectivity (%) = 1-(concentration of corresponding substance / sum of concentrations of all generated substances) × 100%.

[0083] Test method for catalyst stability:

[0084] Catalyst life (h) refers to the operating time of the catalyst when the reaction conversion rate and reaction selectivity decay are less than or equal to 80%.

[0085] Example I-1

[0086] The modified molecular sieve catalyst was prepared as follows:

[0087] 20g ZSM-5 molecular sieve was dispersed in 200g ultrapure water, stirred and put into an autoclave, and 1.5MPa nitrogen was filled into the autoclave at a speed of 300rpm. The temperature was raised to 200℃ for water-soluble dealumination for 6h, and then washed with water several times and dried at 100℃ for 12h.

[0088] Disperse 15g of the dried solid in 300g of water containing 2.33g of ZrO(NO3)2. While stirring and heating, slowly add 10% ammonium hydroxide solution dropwise to adjust the pH of the system to 8-9. The system is then heated to 180°C and aged for 12h. The solution is then washed several times with water until the pH is neutral and dried at 120°C for 12h.

[0089] 10.5 g of the dried solid was immersed in 105 g of a 1% methanesulfonic acid solution for 12 hours, followed by solid-liquid separation. The solid was then washed several times with water until the pH reached neutrality and dried at 120°C for 12 hours. The resulting solid was calcined at 150°C under an argon atmosphere for 24 hours to obtain the target catalyst, S-5Zr-D-ZSM-5, which was set aside.

[0090] Comparative Example 1

[0091] Disperse 15g of ZSM-5 molecular sieve in 300g of water containing 2.33g of ZrO(NO3)2. While stirring and heating, slowly add 10% ammonium hydroxide solution dropwise to adjust the pH of the system to 8-9. Then age at 180°C for 12h. Wash several times with water until the solution reaches a neutral pH, then dry at 120°C for 12h.

[0092] 10.5 g of the dried solid was immersed in 105 g of 1% methanesulfonic acid solution for 12 hours, followed by solid-liquid separation. The solid was then washed several times with water until the pH reached neutrality and dried at 120°C for 12 hours. The resulting solid was calcined at 150°C under argon for 24 hours to obtain the target catalyst, S-5Zr-ZSM-5, which was set aside.

[0093] Comparative Example 2

[0094] 20g ZSM-5 molecular sieve was dispersed in 200g ultrapure water, stirred and put into an autoclave, and 1.5MPa nitrogen was filled into the autoclave at a speed of 300rpm. The temperature was raised to 200℃ for water-soluble dealumination for 6h, and then washed with water several times and dried at 100℃ for 12h.

[0095] Disperse 15g of the dried solid in 300g of water containing 2.33g of ZrO(NO3)2. While stirring and heating, slowly add 10% ammonium hydroxide solution dropwise to adjust the pH of the system to 8-9. Then age at 180°C for 12h. Wash several times with water until the solution reaches a neutral pH, then dry at 120°C for 12h.

[0096] 10.5 g of the dried solid was calcined at 150° C. for 24 h in an argon atmosphere to obtain the target catalyst 5Zr-D-ZSM-5, which was set aside.

[0097] Examples I-2 to I-11

[0098] Based on Example I-1, while ensuring that other conditions remain unchanged, the metal type and / or amount in step 2 are changed to obtain a series of target catalysts.

[0099] Catalysts used in fixed bed isomerization processes:

[0100] The catalyst was loaded into a fixed bed reactor, and 1,2,4-trichlorobenzene solution was introduced. N2 was used as the protective gas, and the molar ratio of N2 to reactants was 50:1. The reaction space velocity was controlled to be 0.2h -1 , the reaction temperature is 350°C, the system pressure is 1 MPa, and an isomerized product is obtained. The reaction liquid is collected and analyzed by gas chromatography.

[0101] The catalysts prepared in the examples and comparative examples were used in a fixed-bed isomerization process, and the reaction results are listed in the following table:

[0102] Table 1 Comparison of catalyst results for fixed-bed isomerization reactions

[0103]

[0104] As shown in Table 1, ZSM-5 molecular sieve catalysts without dealumination modification, when used to catalyze the isomerization of polychlorobenzenes, exhibited good conversion rates but poor selectivity for 1,3,5-trichlorobenzene. Catalysts using only dealumination and rare earth metal deposition without sulfonic acid modification exhibited slightly improved selectivity but poor conversion rates. The present invention utilizes a catalyst with dual rare earth metal-sulfonic acid active sites after dealumination, maintaining high conversion rates while significantly improving selectivity for 1,3,5-trichlorobenzene, demonstrating significant commercial significance.

[0105] Examples II-1 to II-7

[0106] On the basis of Example I-1, while ensuring that the other conditions remain unchanged, the type of protective gas, reaction pressure, reaction temperature, and reaction time of the high-temperature water-soluble dealumination in step (1) were changed to carry out Examples II-1 to II-7 to obtain a series of target catalysts. The catalysts prepared in Examples II-1 to II-7 were used in a fixed-bed isomerization process, and the reaction results are listed in the following table:

[0107] Table 2 Comparison of catalyst results for fixed-bed isomerization reactions

[0108]

[0109] From the above results, it can be seen that the high-temperature water-soluble dealumination in step (1) can be carried out using a variety of protective gases and reaction conditions.

[0110] Examples III-1 to III-5

[0111] On the basis of Example I-1, while keeping other conditions unchanged, the concentration of the ammonium hydroxide solution, the aging temperature and the aging time in step (2) were changed to carry out Examples III-1 to III-5 to obtain a series of target catalysts. The catalysts prepared in Examples III-1 to III-5 were used in a fixed-bed isomerization process. The reaction results are listed in the following table:

[0112] Table 3 Comparison of catalyst results for fixed-bed isomerization reactions

[0113]

[0114] From the above results, it can be seen that the aging step in step (2) is preferably carried out at an aging temperature of 160-180°C and an aging time of 24-48 hours.

[0115] Examples IV-1 to IV-11

[0116] On the basis of Example I-1, while keeping other conditions unchanged, the type, concentration, mass and impregnation time of the organic sulfonic acid solution in step (3) were changed to carry out Examples IV-1 to IV-11 to obtain a series of target catalysts. The catalysts prepared in Examples IV-1 to IV-11 were used in a fixed-bed isomerization process. The reaction results are listed in the following table:

[0117] Table 4 Comparison of catalyst results for fixed-bed isomerization reactions

[0118]

[0119] From the data in Table 4, it can be seen that the preferred sulfonate concentration is 0.75-2.75%, and the preferred solid-liquid ratio is 1:10-1:30.

[0120] Examples V-1 to V-6

[0121] On the basis of Example I-1, while keeping other conditions unchanged, the calcination temperature and time in step (4) and the type of protective atmosphere were changed to carry out Examples V-1 to V-6 to obtain a series of target catalysts. The catalysts prepared in Examples V-1 to V-6 were used in a fixed-bed isomerization process. The reaction results are listed in the following table:

[0122] Table 5 Comparison of catalyst results for fixed-bed isomerization reactions

[0123]

[0124] From the above results, it can be seen that the calcination in step (4) can be carried out using a variety of protective gases and reaction conditions.

[0125] Examples VI-1 to VI-2

[0126] On the basis of Example I-1, ensuring that other conditions remain unchanged, 1,2,4-trichlorobenzene is replaced with other halogenated organic compounds to carry out Examples VI-1 to VI-2, and the fixed bed isomerization process parameters are changed. The reaction results are as follows:

[0127] Table 6 Comparison of catalyst results for fixed-bed isomerization reactions

[0128]

[0129] From the data in Table 6, it can be seen that the molecular sieve catalyst prepared by the modification method of the present invention can improve the selectivity of isomerized products for the isomerization reaction of various halogenated organic compounds, especially for benzene substituted with multiple chlorine atoms, it can selectively isomerize one or two chlorine atoms, thereby improving the selectivity of m-dichlorobenzene or 1,3,5-trichlorobenzene, and can be used for the isomerization of halogenated organic mixtures.

[0130] Examples VII-1 to VII-5

[0131] On the basis of Example I-1, with the remaining conditions unchanged, 1,2,4-trichlorobenzene was used as the substrate, and the fixed-bed isomerization process parameters were changed to carry out Examples VII-1 to VII-5, and the reaction results were as follows:

[0132] Table 7 Comparison of catalysts for fixed-bed isomerization reaction results

[0133]

[0134] From the data in Table 7, it can be seen that the reaction can be run at a space velocity of 0.05 to 0.5, and the reaction can be converted at a lower space velocity under milder conditions, and the preferred space velocity for the reaction is 0.05 to 0.3 h -1 , the temperature is 300 to 350°C, and the pressure is 0.5 to 1.5 MPa.

[0135] Example VIII

[0136] On the basis of Example I-1, with the remaining conditions unchanged, the reaction time was extended, and the running life of the catalyst was evaluated, and the reaction results were as follows:

[0137] Table 8 Catalyst for fixed-bed isomerization reaction stability evaluation

[0138] Reaction time / h Conversion rate / % 1,3,5-Trichlorobenzene selectivity / % 12 59.7 94.8 24 59.8 94.6 36 59.7 94.5 48 60.1 94.6 60 60.0 94.3 72 59.6 94.5 94 59.4 94.1 120 59.4 94.5 180 59.1 94.0 240 59.2 94.1 300 58.8 93.9 400 59.0 94.0 500 58.6 93.7

[0139] From the data in Table 8, it can be seen that the reaction was run for 500 h, and there was no significant attenuation in the conversion rate and selectivity, and the catalyst stability was good.

[0140] The above description is only a preferred embodiment of the present application, and is not intended to limit the scope of the technical content of the present application, and the technical content of the present application is broadly defined in the scope of the claims, and any technical entity or method completed by others, if it is the same as the claims defined in the application, or is an equivalent change, will be considered to be included in the claims.

[0141] All the documents mentioned in the present application are cited as references in the present application, just as each document is cited as a reference. In addition, it should be understood that after reading the above description of the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope defined by the claims attached to the present application.

Claims

1. A method for modifying a ZSM series molecular sieve catalyst, comprising the following steps: (1) Dealumination of the ZSM series molecular sieve catalyst followed by a first washing and drying process; (2) dispersing the catalyst obtained in step (1) in a metal salt aqueous solution, and adding an alkaline solution to adjust the pH of the system to 8-11 for aging, followed by a second washing and drying treatment, wherein the metal ions in the metal salt include rare earth metal ions, and the acid ions include one or more of nitrate, acetate, sulfate, phosphate, and hydrochloride, and the mass ratio of the metal salt, catalyst, and water is 0.01-0.15:1:4-40, wherein the mass of the metal salt is calculated as the amount of metal; (3) impregnating the catalyst obtained in step (2) in an organic sulfonic acid solution or a salt thereof, and performing a third washing and drying treatment after separation, wherein the organic sulfonic acid comprises at least one small molecule sulfonic acid selected from the group consisting of methanesulfonic acid, ethylsulfonic acid, and 1-propylsulfonic acid; (4) calcining the catalyst obtained in step (3) to obtain a modified ZSM series molecular sieve catalyst.

2. The method according to claim 1, wherein The dealumination in step (1) is carried out in the following manner: the molecular sieve is dispersed in water under a protective atmosphere at a temperature of 150-310° C. to carry out water-soluble dealumination.

3. The method according to claim 1 or 2, wherein: The molecular sieve is ZSM-5 molecular sieve, the silicon-aluminum ratio of the molecular sieve is ≥30, and the specific surface area is ≥250 m 2 / g, mesh size 15-80 mesh.

4. The method according to claim 1 or 2, wherein: The rare earth metal ions include one or more of Zr, La, Ce, Pr, and Nd, and the acid ions include nitrate and / or hydrochloride.

5. The method according to claim 1 or 2, wherein: In the step (3), the concentration of the organic sulfonic acid or its salt solution is 0.5-3%.

6. The method according to claim 1 or 2, wherein: The mass ratio of the catalyst obtained in step (2) to the organic sulfonic acid or its salt solution is 1:5 to 1:

40.

7. A ZSM series modified molecular sieve catalyst prepared according to the method of any one of claims 1 to 6.

8. A method for isomerization of halogenated aromatic compounds, wherein the method uses the ZSM series modified molecular sieve catalyst according to claim 7 for the reaction.

9. The method of claim 8, wherein the halogenated aromatic compound comprises at least one compound selected from the group consisting of 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, and 1,2,4-trichlorobenzene.

10. The isomerized product prepared by the method according to any one of claims 8-9.

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