Method for modifying a molecular sieve catalyst and its use in the isomerization of polychlorobenzenes

Abstract

The present application relates to the field of catalyst, in particular to a kind of modification method of molecular sieve catalyst and its application in polychlorobenzene isomerization, the modification method of molecular sieve catalyst includes the following steps: (1) molecular sieve catalyst is carried out dealumination, then carries out first washing and drying treatment;(2) the catalyst obtained in step (1) is dispersed in aqueous solution of metal salt, and pH is adjusted to 8-11 by adding alkali solution to carry out aging, then carries out second washing and drying treatment, wherein the mass ratio of metal salt, catalyst and water is 0.01~0.15:1:4~40, wherein the mass of metal salt is calculated by metal amount;(3) the catalyst obtained in step (2) is impregnated in organic sulfonic acid or its salt solution, after separation, carries out third washing and drying treatment;(4) the catalyst obtained in step (3) is calcined, and modified molecular sieve catalyst is obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysts, in particular to a modification method of a molecular sieve catalyst, and application of the modified molecular sieve catalyst in isomerization of polychlorobenzene. BACKGROUND

[0002] M-dichlorobenzene is widely used in pharmaceutical, pesticide and other industries as an intermediate for synthesizing dyes, bactericides and herbicides. However, in the chlorination process of benzene, since chlorine is an ortho and para directing group, the product obtained is usually a mixture of ortho, para and meta dichlorobenzene isomers, which produces a large amount of by-products ortho-dichlorobenzene and para-dichlorobenzene, and also contains a small amount of trichlorobenzene. On the other hand, among the three isomers of trichlorobenzene, 1,3,5-trichlorobenzene is one of the important organic chemical raw materials, which is used for organic synthesis, insecticides and dye synthesis, and is also widely used as a solvent for preparing pesticides, dyes, medicines, electrolytes, lubricating oils and the like, and is a high value-added chemical intermediate. Therefore, in order to solve the problem of more low value-added products in the existing chlorination technology, it is of great significance to develop a process for converting dichlorobenzene to m-dichlorobenzene and trichlorobenzene to 1,3,5-trichlorobenzene.

[0003] Currently, m-dichlorobenzene is synthesized by isomerization of o-dichlorobenzene or p-dichlorobenzene as raw material with the help of anhydrous aluminum chloride catalyst in industry, but the catalyst needs to be removed by hydrolysis after the reaction is completed, 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 a method for preparing m-dichlorobenzene from p-dichlorobenzene using a sulfonate- immobilized solid acid catalyst, which has a m-dichlorobenzene yield of 81.9% at 300°C, and can be recycled for 6 times, which preliminarily explores the problem of catalyst recovery in isomerization system. In addition, patent CN103708994A discloses another way to prepare m-dichlorobenzene, which uses nano ZSM-5 molecular sieve, nano ZSM-5 molecular sieve modified by acid dealumination or nano ZSM-5 molecular sieve modified by alkali desilication as catalyst, and carries out the reaction in a fixed bed to make p-dichlorobenzene isomerize. This method has a conversion rate of 55.8% and a selectivity of 88.2% at 450°C, a system pressure of 3 MPa and a space velocity of 1 h -1

[0004] ​Based on the above research, the acid molecular sieve as an environmentally friendly solid acid catalyst can replace aluminum chloride to catalyze the isomerization reaction of o-, p-dichlorobenzene, and due to its unique characteristics, it can be continuously operated under fixed bed conditions, but there is still a problem of activity stability. Therefore, there is an urgent need in the art to develop a method for modifying a molecular sieve catalyst, which has both stability and high selectivity, and can be continuously operated for a long period of time for the isomerization reaction of polychlorobenzene. SUMMARY

[0005] The first aspect of the present application provides a method for modifying a molecular sieve catalyst, which comprises the following steps:

[0006] (1) De-aluminizing the molecular sieve catalyst, followed by first washing and drying treatment;

[0007] (2) dispersing the catalyst obtained in step (1) in an aqueous solution of a metal salt, and adding an alkali solution to adjust the pH of the system to 8-11 for aging, followed by 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 based on the amount of metal;

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

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

[0010] In an embodiment of the present application, the de-aluminization of step (1) is carried out by dispersing the molecular sieve in water under a protective atmosphere and at a temperature of 150-310°C for aqueous de-aluminization.

[0011] In an embodiment of the present application, the molecular sieve is ZSM-5 molecular sieve, and the silica-alumina ratio of the molecular sieve is ≥30, the specific surface area is ≥250 m 2 / g, and the mesh number is 15-80 mesh.

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

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

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

[0015] In one embodiment of the present application, the alkaline solution in step (2) comprises 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 halogenated aromatic compounds, wherein the method uses the modified molecular sieve catalyst of the present application.

[0027] In one embodiment of the present application, 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 application provides an isomerization product prepared according to the isomerization reaction method described herein. DETAILED DESCRIPTION

[0029] The present inventors have found that by performing a hydrothermal dealumination modification of a molecular sieve catalyst, new solid acid sites are restructured, enabling long-term continuous isomerization of dichlorobenzene, and even trichlorobenzene compounds. On this basis, the present application is completed.

[0030] "Ranges" disclosed herein are defined, for each specific range by a lower and an upper limit, the lower and upper limit defining the boundaries of a particular range. Ranges defined by the lower and upper limit can be inclusive or exclusive of the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4 and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise stated, a numerical range "a-b" indicates a shorthand way of describing each and every intervening real number between the upper and lower limit, wherein a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, "0-5" is merely a shorthand way of describing these numerical combinations. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

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

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

[0033] In the present application, if not 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 sequence, 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, if not otherwise specified, "comprise" and "include" mentioned herein means open-ended, and can also be closed-ended. For example, "comprise" and "include" 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" are inclusive of the number, and "several" 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 of the following conditions satisfy 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, if not otherwise specified, the percentage (%) or the part refers to the percentage by weight or the parts by weight of the composition.

[0038] In the present application, if not otherwise specified, the sum of the contents of the components in the composition is 100%.

[0039] In the present application, if not 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, for example, two, three, four, and up to the maximum possible multi-component mixture.

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

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

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

[0044] (1) dealuminating the molecular sieve catalyst, followed by a first washing and drying treatment;

[0045] (2) dispersing the catalyst obtained in step (1) in an aqueous solution of a metal salt, and adding an alkali 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 based on the amount of metal;

[0046] (3) impregnating the catalyst obtained in step (2) in a solution of an organic sulfonic acid or a salt thereof, and after separation, 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, and the protective gas pressure is 1-10 MPa, and the water-soluble time is 2-12 h.

[0049] In the present application, 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, which has a large external specific surface area, a high intracrystalline diffusion rate and a channel structure. It can be used for catalyzing the isomerization of dichlorobenzene or trichlorobenzene to prepare m-dichlorobenzene or 1,3,5-trichlorobenzene. ZSM-5 molecular sieve has a very high silicon-aluminum ratio, and its silicon-aluminum ratio can be varied in a broad range of 10 to 3000 or more. In an embodiment of the present application, the silicon-aluminum ratio of the molecular sieve is ≥30, preferably ≥40, the specific surface area is ≥250 m 2 / g, preferably ≥300 m 2 / g, and the mesh number is 15-80 mesh, preferably 20-60 mesh.

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

[0051] In the present application, first, at least part of Al atoms in the framework of the molecular sieve is selectively removed by dealumination of the molecular sieve, to form a mesoporous structure rich in Si-OH defects while ensuring the integrity of the pore structure. The dealumination step can be performed by acid dealumination, steam dealumination, high-temperature aqueous dealumination, etc. The specific way of dealumination of the molecular sieve is not particularly limited, as long as the pore structure is not excessively damaged.

[0052] In an embodiment of the present application, the step of dealumination of the molecular sieve is performed by dispersing the molecular sieve in water under a protective atmosphere and at a temperature of 150-310°C, preferably 200-275°C, for aqueous dealumination. The aqueous dealumination can be performed under stirring. The water can be ultrapure water, deionized water, etc., preferably ultrapure water. The solid-liquid ratio of the dispersion of the molecular sieve and water is 1:10-50 by mass. The type of the protective atmosphere is not particularly limited and can be an inert gas, nitrogen, etc. Preferably, the protective atmosphere comprises at least one gas selected from the group consisting of nitrogen, argon, helium and carbon dioxide. The pressure of the protective atmosphere is 1-10 MPa and the aqueous dealumination time is 2-12 h.

[0053] In step (1), after the dealumination is completed, the molecular sieve is subjected to first washing and drying. The conditions for washing and drying are not particularly limited. In an embodiment of the present application, water is used for washing, the first drying temperature is 40-120°C and the drying time is 6-72 h.

[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 Zr and rare earth metal ions, preferably one or more of Zr, La, Ce, Pr and Nd, and the acid root ions include one or more of nitrate, acetate, sulfate, phosphate and chloride, preferably nitrate and / or chloride. The mass ratio of the metal salt (metal amount), the 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 dealumination vacancies by in-situ coordination to form a rare earth-silicon hydroxyl composite Lewis acid center. An alkali solution including ammonium hydroxide solution and / or ammonia is added to adjust the pH of the system to 8-11 for aging at a temperature of 140-200°C, preferably 160-180°C, for 12-48 h, preferably 24-59 h. Subsequently, second washing and drying treatment is performed, and the conditions for washing and drying are not particularly limited. In an embodiment of the present application, water is used for washing until the solution pH is neutral, the second drying temperature is 80-120°C and the drying time is 6-24 h.

[0055] In step (3), the catalyst obtained in step (2) is immersed in a solution of an organic sulfonic acid or a salt thereof. The organic sulfonic acid is a small-molecule organic sulfonic acid, including but not limited to alkyl sulfonic acid, benzene sulfonic acid, halogenated sulfonic acid, etc. The organic sulfonic acid salt that can be used includes but is not limited to sodium methanesulfonate, sodium ethanesulfonate, etc. In an embodiment of the present application, the organic sulfonic acid includes at least one small-molecule sulfonic acid selected from the group consisting of methyl sulfonic acid, ethyl sulfonic acid, 1-propyl sulfonic acid. The concentration of the solution of the organic sulfonic acid or the salt thereof 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 solution of the organic sulfonic acid or the salt thereof 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 with rare earth-silicon hydroxyl complex Lewis acid center obtained in step (2) is immersed in the solution of the organic sulfonic acid or the salt thereof for sulfonic acid group functional modification, -SO3- coordination grafting occurs on the surface of the rare earth metal, forming a rare earth-sulfonic acid double active interface with electronic modulation function. After the sulfonic acid group functional modification is completed, the molecular sieve catalyst is separated and then subjected to a third washing and drying treatment. The conditions for washing and drying are not particularly limited. In an embodiment of the present application, water is used for washing, the washing is performed until the solution pH is about neutral, the third drying temperature is 80-120°C, and the drying time is 6-24h.

[0056] In step (4), the catalyst obtained in step (3) is calcined. In the present application, the specific means and methods for calcining the catalyst 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 performed in an inert gas, and the inert gas includes one of N2, He, Ne and Ar. In the present application, the conventional calcination temperature in the art can be used. In an embodiment of the present application, the calcination temperature is 100-200°C, and the calcination time is 8-36h.

[0057] In the present application, the specific means and methods for separating, washing and drying the catalyst are not particularly limited as long as the purpose of the present application can be achieved. The drying step can be performed in an inert gas atmosphere or vacuum drying. The solvent used for washing includes one or more of water, methanol, ethanol, isopropanol, acetonitrile, and water is preferably used as the solvent.

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

[0059] In one embodiment of the present application, the temperature rising process of the calcination stage can be single gradient temperature rising or double gradient temperature rising. The single gradient temperature rising procedure includes rising the temperature to the calcination temperature at a temperature rising rate of 0.2-1.0℃ / min; the double gradient temperature rising procedure includes rising the temperature to a gradient temperature of 200-300℃ at a temperature rising rate of 0.5-2℃ / min, maintaining for 2-12h, and then rising the temperature to the calcination temperature at a temperature rising rate of 4-10℃ / min.

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

[0061] In another aspect of the present application, a method for isomerization reaction of halogenated aromatic compounds is provided, which uses the modified molecular sieve catalyst of the present application.

[0062] In the present application, the "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, iodine. The halogenated organic compound includes, but is not limited to, chlorinated aromatic hydrocarbon, brominated aromatic hydrocarbon, etc. The halogenated organic compound preferably includes polychlorinated aromatic hydrocarbon. In one embodiment of the present application, the halogenated aromatic compound includes one or more of 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 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℃, the catalyst mass space velocity can be 0.05-0.5h -1 , the pressure can be 0.5-2MPa, the protective gas can be inert gas, and the molar ratio of inert gas to reactant can be 50-100.

[0064] In another aspect of the present application, an isomerization product prepared according to the isomerization reaction method described herein is provided.

[0065] Taking 1,2-dichlorobenzene and 1,4-dichlorobenzene as examples, the chlorines at 1,2- and 1,4-positions are converted by catalytic isomerization to obtain 1,3-dichlorobenzene, which is an important intermediate required in industry; taking 1,2,3-trichlorobenzene and 1,2,4-trichlorobenzene as examples, the chlorines at 1,2,3- and 1,2,3-positions are converted by catalytic isomerization to obtain 1,3,5-trichlorobenzene, which is also an important high-value chemical intermediate required in industry. The modified molecular sieve catalyst of the present application can improve the selectivity of 1,3-dichlorobenzene and 1,3,5-trichlorobenzene, and can realize long-time continuous isomerization reaction.

[0066] The present application has the following advantages:

[0067] 1. The present application innovatively adopts a step-by-step topology modification strategy, first selectively removes Al atoms in the molecular sieve framework by vapor-phase dealumination method, forms a mesoporous structure rich in Si-OH defects under the condition of ensuring the integrity of the channel structure.

[0068] 2. A second metal species (such as Ce³+) is anchored at the dealuminated vacancy site by in-situ coordination deposition method, a rare earth-silicon hydroxyl composite Lewis acid center is constructed, and then sulfonic acid group functional modification is adopted to cause -SO3⁻ coordination grafting on the surface of the rare earth metal, forming a rare earth-sulfonic acid double active interface with electronic modulation function: the strong Lewis acid site formed by the rare earth metal and the framework oxygen polarizes and activates the C-Cl bond in the polychlorobenzene molecule; the medium-strong Brønsted acid site produced by the coordination of the sulfonic acid group with the rare earth metal further promotes the protonation and removal of Cl⁻.

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

[0070] Unless otherwise specified, the various raw materials of the present application can be obtained by market purchase; or prepared according to the conventional methods in the art. Unless otherwise defined or specified, all professional and scientific terms used herein have the same meaning as familiar to those skilled in the art. In addition, any method and material similar or equivalent to those described can be applied in the method of the present application. Other aspects of the present application are obvious to those skilled in the art from the disclosure herein. Examples

[0071] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not used to limit the scope of the present application. The experimental methods in the following examples without specific conditions are generally determined according to the national standards. If there is no corresponding national standard, it is carried out according to the general international standard, the conventional condition, or the condition suggested by the manufacturer. Unless otherwise specified, all parts are weight parts, all percentages are weight percentages, and the polymer molecular weight is number average molecular weight.

[0072] Source and preparation of raw materials

[0073]

[0074]

[0075] The 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, wherein

[0076] Conversion (%) = 1 - (substrate concentration after reaction / substrate concentration before reaction) x 100%,

[0077] Selectivity (%) = 1 - (corresponding substance concentration / all generated substance concentration and) x 100%.

[0078] Test method for catalyst stability:

[0079] Catalyst life (h) refers to the running time of the catalyst when the reaction conversion rate and the reaction selectivity decay is less than or equal to 80%.

[0080] Example I-1

[0081] The modified molecular sieve catalyst is prepared according to the following method:

[0082] 20 g of ZSM-5 molecular sieve is dispersed in 200 g of ultrapure water, after stirring, it is put into an autoclave, 1.5 MPa of nitrogen is filled in the autoclave, the rotation speed is 300 rpm, and it is heated to 200°C for 6 hours of water-soluble dealumination, and then it is washed with water for several times and dried at 100°C for 12 hours.

[0083] 15 g of the dried solid is dispersed in 300 g of water containing 2.33 g of ZrO (NO3)2, while stirring and heating, 10% ammonium hydroxide solution is slowly added to adjust the pH of the system to 8-9, and then the system is heated to 180°C for 12 hours of aging. After washing with water for several times until the solution pH is neutral, it is dried at 120°C for 12 hours.

[0084] The dried solid 10.5 g is immersed in 105 g of 1% methyl sulfonic acid aqueous solution for 12 hours, solid-liquid separation is performed, and then the system is washed with water for several times until the pH is neutral, and then it is dried at 120°C for 12 hours. The obtained solid is calcined at 150°C for 24 hours in an argon atmosphere to obtain the target catalyst S-5Zr-D-ZSM-5, which is ready for use.

[0085] Comparative Example 1

[0086] 15 g of ZSM-5 molecular sieve is dispersed in 300 g of water containing 2.33 g of ZrO (NO3)2, while stirring and heating, 10% ammonium hydroxide solution is slowly added to adjust the pH of the system to 8-9, and then it is aged at 180°C for 12 hours. After washing with water for several times until the solution pH is neutral, it is dried at 120°C for 12 hours.

[0087] The dried solid 10.5 g is immersed in 105 g of 1% methyl sulfonic acid solution for 12 hours, solid-liquid separation is performed, and then the system is washed with water for several times until the pH is neutral, and then it is dried at 120°C for 12 hours. The obtained solid is calcined at 150°C for 24 hours in an argon atmosphere to obtain the target catalyst S-5Zr-ZSM-5, which is ready for use.

[0088] Comparative Example 2

[0089] 20 g ZSM-5 molecular sieve was dispersed in 200 g ultrapure water, and after stirring, it was put into an autoclave. The autoclave was filled with 1.5 MPa nitrogen, the rotation speed was 300 rpm, and the temperature was raised to 200°C for 6 hours of water-soluble dealumination. Then, after washing with water several times, the solid was dried at 100°C for 12 hours.

[0090] 15 g of the dried solid was dispersed in 300 g of water containing 2.33 g of ZrO(NO3)2, and while stirring and heating, 10% ammonium hydroxide solution was slowly added to adjust the pH of the system to 8-9. Then, after aging at 180°C for 12 hours, the solid was washed with water several times until the solution pH was neutral, and then dried at 120°C for 12 hours.

[0091] The dried solid 10.5 g was calcined at 150°C for 24 hours under an argon atmosphere to obtain the target catalyst 5Zr-D-ZSM-5, which was ready for use.

[0092] Examples I-2 to I-11

[0093] Based on Example I-1, the remaining conditions were unchanged, and the metal species and / or amount used in step 2 was changed to obtain a series of target catalysts.

[0094] The catalyst was used in a fixed-bed isomerization process:

[0095] The catalyst was loaded into a fixed-bed reactor, and a 1,2,4-trichlorobenzene solution was introduced, with N2 as a protective gas. The molar ratio of N2 to reactant was 50:1, and the reaction space velocity was controlled at 0.2h -1 The reaction temperature was 350°C, and the system pressure was 1 MPa. The isomerization product was obtained, and the reaction liquid was collected for gas chromatography analysis.

[0096] The catalysts prepared in the examples and comparative examples were used in a fixed-bed isomerization process, and the results of the reaction are shown in the following table:

[0097] Table 1 Comparison of the results of the fixed-bed isomerization reaction of the catalysts

[0098]

[0099] As can be seen from the data in Table 1, the ZSM-5 molecular sieve catalyst without dealumination modification has a poor selectivity for 1,3,5-trichlorobenzene when used to catalyze the isomerization of polychlorobenzene, although the conversion rate is not poor. The catalyst that only uses dealumination and deposition of rare earth metals but is not modified by sulfonic acid groups has a slightly improved selectivity, but the conversion rate is poor. The catalyst that uses dealumination followed by the formation of a rare earth metal-sulfonic acid dual active site can maintain a high conversion rate and greatly improve the selectivity of 1,3,5-trichlorobenzene, which has extremely high commercial significance.

[0100] Examples II-1 to II-7

[0101] On the basis of Example I-1, keeping other conditions unchanged, changing the kind of protective gas, reaction pressure, reaction temperature and reaction time in step (1) of high-temperature aqueous de-alumination, a series of target catalysts were obtained in Examples II-1 to II-7. The catalysts prepared in Examples II-1 to II-7 were used in fixed-bed isomerization process, and the reaction results are listed in the following table:

[0102] Table 2 Comparison of catalysts used in fixed-bed isomerization reaction results

[0103]

[0104] From the above results, it can be seen that high-temperature aqueous de-alumination in step (1) can be carried out using various protective gases and reaction conditions.

[0105] Examples III-1 to III-5

[0106] On the basis of Example I-1, keeping other conditions unchanged, changing the concentration of ammonium hydroxide solution, the temperature and time of aging in step (2), a series of target catalysts were obtained in Examples III-1 to III-5. The catalysts prepared in Examples III-1 to III-5 were used in fixed-bed isomerization process, and the reaction results are listed in the following table:

[0107] Table 3 Comparison of catalysts used in fixed-bed isomerization reaction results

[0108]

[0109] 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.

[0110] Examples IV-1 to IV-11

[0111] On the basis of Example I-1, keeping other conditions unchanged, changing the kind of organic sulfonic acid solution, the concentration, the mass and the impregnation time in step (3), a series of target catalysts were obtained in Examples IV-1 to IV-11. The catalysts prepared in Examples IV-1 to IV-11 were used in fixed-bed isomerization process, and the reaction results are listed in the following table:

[0112] Table 4 Comparison of catalysts used in fixed-bed isomerization reaction results

[0113]

[0114] From the data in Table 4, it can be seen that the sulfonate concentration is preferably 0.75-2.75%, and the solid-liquid ratio is preferably 1:10-1:30.

[0115] Examples V-1 to V-6

[0116] On the basis of Example I-1, keeping other conditions unchanged, changing the calcination temperature and time in step (4) and the type of protective atmosphere, a series of target catalysts were prepared in Examples V-1 to V-6. The catalysts prepared in Examples V-1 to V-6 were used in the fixed bed isomerization process, and the reaction results are listed in the following table:

[0117] Table 5 Comparison of catalysts used in fixed bed isomerization reaction results

[0118]

[0119] From the above results, it can be seen that the calcination in step (4) can be carried out using various protective gases and reaction conditions.

[0120] Examples VI-1 to VI-2

[0121] On the basis of Example I-1, keeping other conditions unchanged, 1,2,4-trichlorobenzene was replaced with other halogenated organic compounds to prepare Examples VI-1 to VI-2, and the fixed bed isomerization process parameters were changed, and the reaction results are as follows:

[0122] Table 6 Comparison of catalysts used in fixed bed isomerization reaction results

[0123]

[0124] From the data in Table 6, it can be seen that the molecular sieve catalyst prepared by the modification method of the present application can improve the selectivity of isomerization products for various halogenated organic isomerization reactions, especially for benzene substituted with multiple chlorine atoms, which can selectively isomerize one or two chlorine atoms to improve the selectivity of m-dichlorobenzene or 1,3,5-trichlorobenzene, and can be used for the isomerization of halogenated organic mixtures.

[0125] Examples VII-1 to VII-5

[0126] On the basis of Example I-1, keeping other conditions unchanged, 1,2,4-trichlorobenzene was used as the substrate, and the fixed bed isomerization process parameters were changed to prepare Examples VII-1 to VII-5, and the reaction results are as follows:

[0127] Table 7 Comparison of catalysts used in fixed bed isomerization reaction results

[0128]

[0129] 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. The comprehensive reaction preferably has a space velocity of 0.05 to 0.3 h"1, a temperature of 300 to 350°C, and a pressure of 0.5 to 1.5 MPa.

[0130] Example VIII

[0131] On the basis of Example I-1, the remaining conditions were kept unchanged, the reaction time was extended, and the running life of the catalyst was evaluated. The reaction results are as follows:

[0132] Table 8 Stability evaluation of the catalyst for fixed-bed isomerization reaction

[0133]

[0134] From the data in Table 8, it can be seen that the reaction was run for 500 h, and there was no obvious attenuation in conversion and selectivity, and the catalyst had good stability.

[0135] The above description is merely preferred embodiments of the present application, but not to confine the scope of the technical content of the present application, the technical content of the present application is defined in the scope of the claims, any other technical entity or method, if it is the same as the claims defined in the application, or an equivalent change, will be regarded as covered in the claims.

[0136] All the documents mentioned in the present application are cited as references in the present application, as if each document is cited as a reference individually. 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 of the claims attached to the present application.

Claims

1. A method for modifying a ZSM series molecular sieve catalyst, the method comprising the following steps: (1) de-aluminating a ZSM series molecular sieve catalyst, followed by a first washing and drying treatment; (2) dispersing the catalyst obtained in step (1) in an aqueous solution of a metal salt, and adding an alkali solution to adjust the pH of the system to 8-11 for aging, followed by a second washing and drying treatment, wherein the metal ion in the metal salt comprises Zr or a rare earth metal ion, the acid radical ion comprises one or more of nitrate, acetate, sulfate, phosphate, and chloride, and 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 based on the amount of metal; (3) impregnating the catalyst obtained in step (2) in a solution of an organic sulfonic acid or a salt thereof, and after separation, performing a third washing and drying treatment, wherein 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; (4) calcining the catalyst obtained in step (3) to obtain a modified ZSM series molecular sieve catalyst.

2. The method of claim 1, wherein, The de-alumination in step (1) is performed by dispersing the molecular sieve in water under a protective atmosphere and at a temperature of 150-310°C.

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

4. The method of claim 1 or 2, wherein, The metal ion comprises one or more of Zr, La, Ce, Pr, and Nd, and the acid radical ion comprises nitrate and / or chloride.

5. The method of claim 1 or 2, wherein, In step (3), the concentration of the solution of the organic sulfonic acid or a salt thereof is 0.5-3% by weight.

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

40.

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

8. A method for isomerization of a halogenated aromatic compound, the method using the ZSM series modified molecular sieve catalyst of claim 7.

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. An isomerization product prepared according to the method of any one of claims 8-9.

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