Pure silicon molecular sieve supported noble metal catalyst as well as preparation method and application thereof

Abstract

The invention relates to a pure silicon molecular sieve supported noble metal catalyst as well as a preparation method and application thereof. The method for preparing the pure silicon molecular sieve loaded noble metal catalyst comprises the following steps: (1) treating a pure silicon molecular sieve by using an alcoholic solution of organic amine under a heating condition, and carrying out solid-liquid separation, washing and drying to obtain a modified pure silicon molecular sieve; (2) dipping the modified pure silicon molecular sieve into a noble metal precursor in a hydrocarbon solvent, and carrying out solid-liquid separation and drying to obtain a catalyst precursor; and (3) roasting the catalyst precursor to obtain the pure silicon molecular sieve supported noble metal catalyst, with the mass ratio of the pure silicon molecular sieve to the noble metal being 1: 0.00005-1: 0.005.

Description

Technical Field

[0001] The present application belongs to the field of catalysts, and specifically relates to a method for preparing a pure silicon molecular sieve loaded with a noble metal catalyst, a catalyst obtained by the method, and a method for hydrogenating and dechlorinating chlorobenzene using the catalyst. Background Art

[0002] Chlorobenzene, dichlorobenzene, trichlorobenzene, tetrachlorobenzene, pentachlorobenzene, and hexachlorobenzene are all toxic, and the more chlorine atoms there are, the more toxic they are. Chlorobenzene is an important organic chemical raw material and is widely used in many industrial fields. Its main uses include as an intermediate for dyes, medicines, pesticides, organic synthesis, as well as as a solvent and rubber additive. The value and market demand of polychlorinated benzenes are often low. Because they are difficult to degrade and toxic, they have great harm to the environment. Most industrial methods for treating polychlorinated benzenes are to treat them as solid waste. However, if high-chlorinated benzene can be converted into low-chlorinated benzene with higher value through hydrodechlorination, it will be of great significance to enhance the vitality of the entire industry. At present, common precious metal hydrodechlorination catalysts are mainly Pd, Pt and Rh catalysts. Precious metal catalysts have high activity, but their selectivity and stability are often low.

[0003] Chinese patent application CN110407663A discloses a method for synthesizing dichlorobenzene, using Pd / C as a catalyst and trichlorobenzene as a substrate, and successfully preparing dichlorobenzene by hydrodechlorination in a kettle reactor. However, the kettle technology used requires the use of a large amount of alkali, which is not conducive to safe production and the reduction of equipment costs. Chinese patent CN111233621B discloses a method for treating dichlorobenzene distillation residue, wherein the Pd catalyst can selectively hydrodechlorinate polychlorobenzenes to benzene through a fixed bed reactor, which has a low added value and still has room for further improvement in selectivity.

[0004] For the hydrodechlorination process in a tubular reactor, the generated HCl poses a problem to the stability of the catalyst due to the lack of alkali absorption. In addition, different catalysts also have problems of metal loss and sintering due to their own structures. Especially in gas-solid two-phase reactions, higher reaction temperatures are often required, and byproducts such as polychlorinated biphenyls (a type of carcinogen) are easily produced at this time, which cokes on the catalyst surface and seriously hinders the active sites of the reaction.

[0005] As can be seen from the above, the currently described catalysts still have problems in selectivity and stability for the selective hydrogenation of chlorobenzene compounds. Therefore, it is necessary to develop an efficient and stable catalyst to selectively hydrogenate and dechlorinate chlorobenzene into low-chlorobenzene products with higher added value, thereby reducing costs for enterprises and achieving green production. Summary of the invention

[0006] The main purpose of the present invention is to provide a noble metal catalyst, which can regulate the distribution of products by adjusting the hydrogen ratio when hydrodechlorination reaction of chlorobenzene is carried out by using the catalyst, and solve the problem that the noble metal catalyst is easy to coke and sinter at high temperature, and effectively improve the stability of the catalyst during hydrodechlorination under high temperature environment. Through in-depth research, the inventors of the present application found that by using pure silicon molecular sieve as a carrier, modifying the pure silicon molecular sieve with organic amine, and then loading ultra-low loading of noble metal, a highly dispersed and highly stable noble metal catalyst can be obtained, thereby achieving the above purpose.

[0007] Therefore, in the first aspect of the present application, a method for preparing a pure silicon molecular sieve supported noble metal catalyst is provided, the method comprising the following steps:

[0008] (1) treating pure silicon molecular sieve with an alcohol solution of an organic amine under heating conditions, and obtaining a modified pure silicon molecular sieve through solid-liquid separation, washing, and drying;

[0009] (2) impregnating the modified pure silicon molecular sieve with a noble metal precursor in a hydrocarbon solvent, performing solid-liquid separation and drying to obtain a catalyst precursor;

[0010] (3) calcining the catalyst precursor to obtain a pure silicon molecular sieve supported noble metal catalyst,

[0011] The mass ratio of pure silicon molecular sieve to precious metal is 1:0.00005 to 1:0.005, preferably 1:0.0001 to 1:0.002, and more preferably 1:0.0001 to 1:0.0015.

[0012] In some embodiments, the pure silicon molecular sieve is one or more selected from the following group: pure silicon Silicalite-1 molecular sieve, pure silicon Beta molecular sieve, pure silicon MCM-41 molecular sieve, pure silicon SBA-15 molecular sieve, ZSM-5 pure silicon molecular sieve.

[0013] In some embodiments, the organic amine is selected from one or more of the following groups: methylamine, dimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, n-propylamine, isopropylamine, dipropylamine and aniline.

[0014] In some embodiments, the alcohol is selected from one or more of the following groups: methanol, ethanol, ethylene glycol, n-propanol, isopropanol and glycerol.

[0015] In some embodiments, the mass ratio of pure silicon molecular sieve to organic amine is 1:0.05 to 1:15. In other embodiments, the mass ratio of pure silicon molecular sieve to organic amine is 1:0.1 to 1:10.

[0016] In some embodiments, the heating temperature in step (1) is 40-200° C. In other embodiments, the heating temperature in step (1) is 50-180° C.

[0017] In some embodiments, the treatment time in step (1) is 0.5-80 hours. In other embodiments, the treatment time in step (1) is 1-72 hours.

[0018] In some embodiments, the noble metal is selected from one or more of the following group: palladium, rhodium, and platinum.

[0019] In some embodiments, the noble metal precursor is selected from one or more of noble metal acetates, oxalates, acetylacetonates, alkyl acetates, carbonyl chlorides, alkyl chlorides, benzylidene acetonates, phenylphosphine chlorides, and ethylenediamine chlorides.

[0020] In some embodiments, the hydrocarbon solvent is selected from one or more of the following groups: benzene, toluene, xylene, mesitylene, propylbenzene, isopropylbenzene, octane, cyclohexane, hexane, isohexane, heptane and isoheptane.

[0021] In some embodiments, the mass ratio of the pure silicon molecular sieve to the hydrocarbon solvent is 1:2 to 1:25. In other embodiments, the mass ratio of the pure silicon molecular sieve to the hydrocarbon solvent is 1:5 to 1:20.

[0022] In some embodiments, before the modified pure silicon molecular sieve is impregnated with a noble metal precursor in a hydrocarbon solvent, the hydrocarbon solvent is desulfurized using a desulfurization catalyst.

[0023] In some embodiments, the desulfurization catalyst is a metal-supported desulfurization agent. The metal is selected from one or more of the following groups: Pd, Pt, Rh, Ru, Au, Ag, Fe, Cu, Ni, Co; the carrier is selected from one or more of a carbon carrier, an oxide carrier, or a molecular sieve carrier. For example, the desulfurization catalyst can be selected from Pd / C, Pt / C, Pd / Al 2 O 3 、Pt / Al 2 O 3 .

[0024] In some embodiments, the mass ratio of the desulfurization catalyst to the hydrocarbon solvent is 1:400 to 1:5000. In other embodiments, the mass ratio of the desulfurization catalyst to the hydrocarbon solvent is 1:500 to 1:2000.

[0025] In a second aspect of the present application, a pure silicon molecular sieve supported noble metal catalyst obtained by the above method is provided.

[0026] In a third aspect of the present application, a method for hydrodechlorination of chlorobenzene is provided, wherein the method uses the above-mentioned pure silicon molecular sieve loaded with a noble metal catalyst. DETAILED DESCRIPTION

[0027] "Scope" disclosed herein is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The scope defined in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. 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 values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope 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 real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it 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.

[0028] 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.

[0029] 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.

[0030] In the present application, unless otherwise specified or there is no inherent sequence relationship, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0031] In this application, unless otherwise specified, the terms "include" and "comprising" mentioned herein may be open-ended or closed-ended. For example, the terms "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0032] In the description of this article, it should be noted that, unless otherwise specified, "above" and "below" are inclusive of the number itself, and "several" in "one or several" means two or more.

[0033] 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 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).

[0034] Herein, unless otherwise specified, percentage (%) or part refers to percentage by weight or part by weight relative to the composition.

[0035] If not specifically stated, the terms "a" or "an" used in the present specification means "at least one".

[0036] In one aspect, the present application provides a method for preparing a pure silicon molecular sieve supported noble metal catalyst, the method comprising the following steps:

[0037] (1) treating pure silicon molecular sieve with an alcohol solution of an organic amine under heating conditions, and obtaining a modified pure silicon molecular sieve through solid-liquid separation, washing, and drying;

[0038] (2) impregnating the modified pure silicon molecular sieve with a noble metal precursor in a hydrocarbon solvent, performing solid-liquid separation and drying to obtain a catalyst precursor;

[0039] (3) calcining the catalyst precursor to obtain a pure silicon molecular sieve supported noble metal catalyst,

[0040] The mass ratio of pure silicon molecular sieve to precious metal is 1:0.00005 to 1:0.005.

[0041] Pure silicon molecular sieves are also called all-silicon molecular sieves, which are known in the art and can be purchased commercially or prepared by oneself. For example, the pure silicon molecular sieve can be selected from one or more of the following groups: pure silicon Silicalite-1 molecular sieve, pure silicon Beta molecular sieve, pure silicon MCM-41 molecular sieve, pure silicon SBA-15 molecular sieve, ZSM-5 pure silicon molecular sieve.

[0042] The organic amine used to modify the pure silicon molecular sieve can be selected from one or more of the following groups: methylamine, dimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, n-propylamine, isopropylamine, dipropylamine and aniline. In the present application, treating the pure silicon molecular sieve with an alcohol solution of an organic amine includes first preparing an alcohol solution of the organic amine, then adding the pure silicon molecular sieve to the solution, and also includes mixing the organic amine, alcohol and pure silicon molecular sieve in any order. The type of alcohol used is not particularly limited, as long as it can dissolve the organic amine used. For example, the alcohol can be selected from one or more of the following groups: methanol, ethanol, ethylene glycol, n-propanol, isopropanol and glycerol. A stirring device can be used for stirring during the treatment process. There is no particular restriction on the amount of alcohol used, as long as an organic amine solution of suitable concentration can be formed. For example, the mass ratio of the organic amine to the alcohol may be 1:150, preferably 1:5 to 1:100, such as 1:70, 1:60, 1:50, 1:40, 1:30, 1:20, 1:10, 1:9, 1:8, 1:7, 1:6, 1:5.

[0043] The mass ratio of pure silicon molecular sieve to organic amine can be 1:0.05 to 1:15, preferably 1:0.1 to 1:10, for example 1:0.2 to 1:9, 1:0.3 to 1:8, 1:0.4 to 1:7, 1:0.5 to 1:6, 1:0.6 to 1:5, 1:0.7 to 1:4, 1:0.8 to 1:3, 1:0.9 to 1:2.

[0044] In step (1), the heating temperature used for the treatment under heating conditions may be 40-200°C, preferably 50-180°C, for example 55-170°C, 60-160°C, 65-150°C, 70-140°C, 75-130°C, 80-120°C, 90-110°C.

[0045] In step (1), the treatment time may be 0.5-80 hours, preferably 1-72 hours, for example 2-70 hours, 3-65 hours, 4-60 hours, 5-55 hours, 6-50 hours, 7-45 hours, 8-40 hours, 9-35 hours, 10-30 hours, 11-25 hours, 12-20 hours, 13-15 hours.

[0046] In step (1), solid-liquid separation can be performed by any conventional solid-liquid separation method known in the art, such as filtration, centrifugal separation, etc. The wet solid obtained by separation is washed, and the washing solvent can be water (such as ultrapure water), methanol, ethanol, etc. Drying can be performed by any conventional drying method known in the art, such as ventilation drying, heating drying, vacuum drying, etc. If heating drying is used, the drying temperature can be, for example, 80-120° C., and the drying time is preferably 12-24 hours.

[0047] The noble metal used in the present application can be selected from one or more of the following groups: palladium, rhodium, platinum. The noble metal precursor used for impregnation can be selected from one or more of acetate, oxalate, acetylacetonate, alkyl acetate, carbonyl chloride, alkyl chloride, benzylidene acetonate, phenylphosphine chloride, ethylenediamine chloride. Specific examples of noble metal precursors include: palladium acetate, palladium acetylacetonate, diethyl rhodium acetate, tetracarbonyl dirhodium dichloride, bisethyl palladium chloride, bis dibenzylidene acetone palladium, trimethyl rhodium acetate, triphenylphosphine platinum chloride, bis (ethylenediamine) platinum chloride, etc. In step (2), the amount of the noble metal precursor can be based on the amount of pure silicon molecular sieve added in step (1), and can be added in a certain mass ratio of pure silicon molecular sieve to the noble metal, and the mass ratio can be 1:0.00005 to 1:0.005, preferably 1:0.0001 to 1:0.002, for example, 1:0.00006 to 1:0.0019, 1:0.00007 to 1:0018, 1:0.00008 to 1:0017, 1:0.00009 to 1:0016, 1:0.0001 to 1:0.0015, 1:0.0 0.0011 to 1:0.0014, 1:0.00012 to 1:0.0013, 1:0.00013 to 1:0.0012, 1:0.00014 to 1:0011, 1:0.00015 to 1:0.001, 1:0.00016 to 1:0.0009, 1:0.00017 to 1:0008, 1:0.00018 to 1:0007, 1:0.00019 to 1:0.0006, 1:0.0002 to 1:0.0005, 1:0.0003 to 1:0.0004. Those skilled in the art can convert the mass of the noble metal into the mass of the corresponding noble metal precursor by calculation.

[0048] In step (2), the pure silicon molecular sieve and the noble metal precursor modified with organic amine are added to a hydrocarbon solvent in any order, stirred and / or ground, and the noble metal precursor is loaded onto the modified pure silicon molecular sieve by impregnation. The noble metal precursor can also be added to the hydrocarbon solvent first, stirred evenly, and then the modified pure silicon molecular sieve is added. The impregnation time can be, for example, 1-80 hours, preferably 2-72 hours, for example, 5-65 hours, 10-60 hours, 15-55 hours, 20-50 hours, 25-45 hours, 30-40 hours. In the present application, a hydrocarbon solvent refers to an organic solvent containing only carbon and hydrogen elements. The hydrocarbon solvent can be selected from one or more of the following groups: benzene, toluene, xylene, mesitylene, propylbenzene, isopropylbenzene, octane, cyclohexane, hexane, isohexane, heptane and isoheptane.

[0049] In step (2), the amount of hydrocarbon solvent added is based on the amount of pure silicon molecular sieve added in step (1), and is added according to a certain mass ratio of pure silicon molecular sieve to hydrocarbon solvent, and the mass ratio may be 1:2 to 1:25, preferably 1:5 to 1:20, for example 1:6 to 1:18, 1:7 to 1:16, 1:8 to 1:14, 1:9 to 1:12.

[0050] In step (2), solid-liquid separation can be carried out by any conventional solid-liquid separation method known in the art, such as filtration, centrifugal separation, etc. The wet solid obtained by separation can be optionally washed. Drying can be carried out by any conventional drying method known in the art, such as ventilation drying, heating drying, vacuum drying, etc. If heating drying is used, the drying temperature can be, for example, 50-150° C., and the drying time is preferably 4-120 hours.

[0051] Before the modified pure silicon molecular sieve is impregnated with a noble metal precursor in a hydrocarbon solvent, the hydrocarbon solvent may be desulfurized with a desulfurization catalyst. The desulfurization catalyst is a metal-supported desulfurizer. The metal is selected from one or more of the following groups: Pd, Pt, Rh, Ru, Au, Ag, Fe, Cu, Ni, Co; the carrier is selected from one or more of a carbon carrier, an oxide carrier or a molecular sieve carrier. The mass ratio of the desulfurization catalyst to the hydrocarbon solvent may be 1:400 to 1:5000, preferably 1:500 to 1:2000, for example, 1:600 ​​to 1:1900, 1:700 to 1:1800, 1:800 to 1:1700, 1:900 to 1:1600, 1:1000 to 1:1500, 1:1100 to 1:1400, 1:1200 to 1:1300.

[0052] In step (3), calcination can be carried out in an inert atmosphere. The inert gas forming the inert atmosphere can be selected from helium, neon, argon, and nitrogen. The calcination temperature can be 250-550° C., such as 300-500° C., 350-450° C. The calcination time can be, for example, 1-30 hours, such as 2-24 hours, 4-22 hours, 6-20 hours, 8-18 hours, 10-16 hours, 12-14 hours.

[0053] On the other hand, the present application provides a pure silicon molecular sieve loaded with a noble metal catalyst obtained by the above method. In the catalyst, the mass ratio of the pure silicon molecular sieve to the noble metal may be 1:0.0001 to 1:0.005, for example, 1:0.0002 to 1:0.0045, 1:0.0004 to 1:0.004, 1:0.0006 to 1:0.0035, 1:0.0008 to 1:0.003, 1:0.001 to 1:0.0025, 1:0.0012 to 1:0.002, 1:0.0014 to 1:0.0018. The noble metal may be selected from one or more of the following groups: palladium, rhodium, platinum.

[0054] In addition, the present application also provides a chlorobenzene hydrodechlorination method, the method using the above-mentioned pure silicon molecular sieve loaded precious metal catalyst. In some exemplary embodiments, the chlorobenzene hydrodechlorination method comprises: reacting chlorobenzene with hydrogen in the presence of the pure silicon molecular sieve loaded precious metal catalyst. In some exemplary embodiments, the chlorobenzene hydrodechlorination method comprises: reacting chlorobenzene with hydrogen in a fixed bed reactor, the fixed bed reactor being loaded with the pure silicon molecular sieve loaded precious metal catalyst. In the present application, chlorobenzene refers to any one or more of chlorobenzene, dichlorobenzene, trichlorobenzene, tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene. Polychlorobenzene refers to any one or more of dichlorobenzene, trichlorobenzene, tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene. Chlorobenzene refers to monochlorobenzene. The hydrodechlorination method of the present application is particularly suitable for polychlorobenzenes, i.e., a polychlorobenzene hydrodechlorination method. In the chlorobenzene hydrodechlorination process, the raw material can be one or more of dichlorobenzene, trichlorobenzene, tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene. In an exemplary embodiment, the reaction temperature of the hydrodechlorination of chlorobenzene may be 200-400°C, such as 250-350°C, such as 300°C. The pressure may be 0.1-1.0 MPa, such as 0.2-0.8 MPa, such as 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa. The space velocity may be 0.5-15 h -1 , for example 1-10h -1 , for example 2h -1 , 3h -1 , 4h -1 , 5h -1 , 6h -1 , 7h -1 , 8h -1 , 9h -1. The hydrogen ratio may be 1-6, such as 1-5, such as 2, 3, 4. The "hydrogen ratio" described in the present application refers to the molar ratio of hydrogen to chlorobenzene raw material. The inventors of the present application unexpectedly discovered that the selectivity of the reaction can be adjusted by adjusting the hydrogen ratio using the pure silicon molecular sieve loaded with precious metal catalysts of the present application. For example, when trichlorobenzene is used as the raw material, by adjusting the hydrogen ratio, a product with chlorobenzene as the main product can be obtained, or a product with dichlorobenzene as the main product can be obtained. The catalysts of the prior art cannot achieve free adjustment of the reaction selectivity. In addition, by using the pure silicon molecular sieve loaded with precious metal catalysts of the present application, high-temperature gas-solid reactions can be achieved, and the catalyst can run for a long time without deactivation. The catalysts of the prior art are prone to coking and deactivation at high temperatures. Without being limited by theory, the inventors of the present application believe that in the pure silicon molecular sieve loaded with precious metal catalyst prepared by the method of the present application, the low content of precious metal is highly dispersed and anchored in the defects on the pure silicon molecular sieve, which can effectively prevent the sintering of precious metal under high temperature reaction conditions. At the same time, the weak acidity of the pure silicon molecular sieve has a strong anti-coking ability. In addition, the selectivity of the reaction can be adjusted by adjusting the hydrogen ratio in the hydrodechlorination reaction of chlorobenzene.

[0055] The technical effects of this application mainly include:

[0056] (1) The pure silicon molecular sieve loaded with precious metal catalysts of the present application can maintain stability and reaction activity for a long time under high temperature reaction conditions.

[0057] (2) The impregnation solution used to prepare the catalyst of the present application can be easily recycled, which is beneficial to cost saving and mass production of the catalyst.

[0058] (3) The pure silicon molecular sieve loaded with precious metal catalyst of the present application can realize high-temperature gas-solid reaction of chlorobenzene hydrodechlorination, and the reaction selectivity can be freely adjusted by adjusting the hydrogen ratio.

[0059] Unless otherwise specified, the various raw materials of the present application can be obtained from the market; 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 disclosed herein. Other aspects of the present disclosure are obvious to those skilled in the art due to the disclosure herein.

[0060] Example

[0061] The present invention will be further described below in conjunction with specific embodiments.

[0062] Main reagents for the experiment

[0063]

[0064]

[0065]

[0066] Main experimental instruments

[0067]

[0068] The conversion and selectivity were obtained by:

[0069] The liquid after the reaction was collected and analyzed by Agilent 7890 gas chromatograph. The mass concentration of each component was calculated by external standard method using hydrogen flame detector (FID).

[0070] Catalyst life (h) refers to the operating time during which the reaction conversion rate and reaction selectivity decay to less than or equal to 80%.

[0071] Example 1

[0072] 100g of pure silicon Silicalite-1 molecular sieve, 50g of ethylamine, and 500g of methanol were mixed and put into a reactor and reacted at 50°C for 72h. Ultrapure water was added to the wet solid after the reaction for washing, and then dried at 80°C for 24h to obtain a dried solid. 2 O 3 The desulfurization catalyst and 500g toluene were put into another reactor for 2h to obtain desulfurized toluene. The dried solid and 0.021g palladium acetate were put into the above desulfurized toluene and impregnated for 72h. The wet solid obtained after impregnation was dried at 120°C for 12h, and then calcined at 300°C in a tubular furnace in a nitrogen atmosphere for 24h to obtain a pure silicon molecular sieve highly dispersed palladium catalyst.

[0073] Take ≥99.9% (based on mass) of 1,2,4-trichlorobenzene raw material, with a mass space velocity of 10h -1 The 1,2,4-trichlorobenzene raw material and hydrogen with a hydrogen ratio of 5 are mixed at a pressure of 0.8MPa, and a hydrogenation dechlorination reaction occurs in a fixed bed layer containing the above-mentioned palladium catalyst at 300°C to generate chlorobenzene. The conversion rate of 1,2,4-trichlorobenzene is 93.7%, the selectivity of chlorobenzene is 88.6%, and the stable operation is 4322h.

[0074] Comparative Example 1 (pure silicon molecular sieve not treated with organic amine)

[0075] 1g Pd / Al 2 O 3The desulfurization catalyst and 500g toluene were put into a reactor for 2h to obtain desulfurized toluene. 100g Silicalite-1 pure silicon molecular sieve and 0.021g palladium acetate were put into 500g desulfurized toluene for 72h. The wet solid obtained after impregnation was dried at 120°C for 12h, and then calcined at 300°C in a tubular furnace in a nitrogen atmosphere for 24h to obtain a pure silicon molecular sieve highly dispersed palladium catalyst.

[0076] Take ≥99.9% 1,2,4-trichlorobenzene raw material, mass space velocity is 10h -1 The 1,2,4-trichlorobenzene raw material and hydrogen with a hydrogen ratio of 5 are mixed at a pressure of 0.8MPa, and a hydrogenation dechlorination reaction occurs in a fixed bed layer containing the above-mentioned palladium catalyst at 300°C to generate chlorobenzene. The conversion rate of 1,2,4-trichlorobenzene is 61.1%, the selectivity of chlorobenzene is 41.2%, and the stable operation is 1124h.

[0077] Comparative Example 2 (hydrocarbon solvent without desulfurization treatment)

[0078] 100g of Silicalite-1 pure silicon molecular sieve, 50g of ethylamine and 500g of methanol were mixed and put into a reactor and reacted at 50°C for 72h. Ultrapure water was added to the wet solid after the reaction for washing, and then dried at 80°C for 24h. The dried solid and 0.021g of palladium acetate were put into 500g of toluene and immersed for 72h. The wet solid obtained after the immersion was dried at 120°C for 12h, and then calcined at 300°C in a tubular furnace in a nitrogen atmosphere for 24h to obtain a pure silicon molecular sieve highly dispersed palladium catalyst.

[0079] Take ≥99.9% 1,2,4-trichlorobenzene raw material, mass space velocity is 10h -1 The 1,2,4-trichlorobenzene raw material and hydrogen with a hydrogen ratio of 5 were mixed at a pressure of 0.8MPa and passed through a fixed bed layer containing the above-mentioned palladium catalyst at 300°C to undergo a hydrodechlorination reaction to produce chlorobenzene. The 1,2,4-trichlorobenzene conversion rate was 46.3%, the chlorobenzene selectivity was 76.26%, and the stable operation lasted for 565 hours.

[0080] Comparative Example 3 (Non-hydrocarbon solvent)

[0081] 100g of Silicalite-1 pure silicon molecular sieve, 50g of ethylamine and 500g of methanol were mixed and put into a reactor and reacted at 50°C for 72h. Ultrapure water was added to the wet solid after the reaction for washing, and then dried at 80°C for 24h. The dried solid and 0.021g of palladium acetate were put into 500g of methanol and immersed for 72h. The wet solid obtained after the immersion was dried at 120°C for 12h, and then calcined at 300°C in a tubular furnace in a nitrogen atmosphere for 24h to obtain a pure silicon molecular sieve highly dispersed palladium catalyst.

[0082] Take ≥99.9% 1,2,4-trichlorobenzene raw material, mass space velocity is 10h -1 The 1,2,4-trichlorobenzene raw material and hydrogen with a hydrogen ratio of 5 are mixed at a pressure of 0.8MPa and passed through a fixed bed layer containing the above-mentioned palladium catalyst at 300°C to undergo a hydrodechlorination reaction to produce chlorobenzene. The conversion rate of 1,2,4-trichlorobenzene is 31.7%, the selectivity of chlorobenzene is 55.31%, and the stable operation is 1344h.

[0083] Example 2 (Oxalate as a noble metal precursor)

[0084] 100g of Silicalite-1 pure silicon molecular sieve, 100g of diethylamine, and 5000g of ethylene glycol were mixed and put into a reactor and reacted at 180°C for 1h. Ethanol was added to the wet solid after the reaction for washing, and then dried at 120°C for 12h to obtain a dried solid. 1g of Pt / Al 2 O 3 The desulfurization catalyst and 2000g of triphenylene were put into a reactor for 48 hours to obtain desulfurized triphenylene. The dried solid and 1.02g of platinum oxalate were put into 2000g of desulfurized triphenylene and impregnated for 24 hours. The wet solid obtained after impregnation was dried at 150°C for 4 hours, and then calcined at 500°C in a tubular furnace in a helium atmosphere for 2 hours to obtain a pure silicon molecular sieve highly dispersed platinum catalyst.

[0085] Take ≥99.9wt% 1,2,4-trichlorobenzene solution, with a mass space velocity of 5h -1 The 1,2,4-trichlorobenzene solution and hydrogen with a hydrogen ratio of 1 are mixed at a pressure of 0.4MPa and passed through a fixed bed containing the above-mentioned platinum catalyst at 300°C to undergo a hydrodechlorination reaction to produce dichlorobenzene. The conversion rate of 1,2,4-trichlorobenzene is 67.4%, the selectivity of dichlorobenzene is 82.7%, and the stable operation is 2081h.

[0086] Example 3 (Palladium acetylacetonate as a noble metal precursor)

[0087] 100g Silicalite-1 pure silicon molecular sieve, 50g propylamine, 500g ethanol and 2000g isopropanol were mixed and put into a reactor and reacted at 100°C for 48h. Ethanol was added to the wet solid after the reaction for washing, and then dried at 100°C for 18h to obtain a dried solid. 1g Pd / C desulfurization catalyst, 800g benzene and 200g cyclohexane were put into a reactor for 24h to obtain a desulfurized benzene and cyclohexane mixed solvent. The dried solid and 0.28g acetylacetone palladium were put into 1000g desulfurized benzene and cyclohexane mixed solvent and immersed for 48h. The wet solid obtained after immersion was dried at 50°C for 120h, and then calcined at 400°C in a tube furnace in a neon atmosphere for 12h to obtain a pure silicon molecular sieve highly dispersed palladium catalyst.

[0088] A mixed feedstock of 67wt% 1,2,4-trichlorobenzene and 33wt% 1,2,4,5-tetrachlorobenzene is prepared with a mass space velocity of 10h -1 A mixed raw material of 1,2,4-trichlorobenzene and 1,2,4,5-tetrachlorobenzene was mixed with hydrogen in a hydrogen ratio of 2 at a pressure of 0.2MPa, and a hydrodechlorination reaction occurred in a fixed bed layer containing the above-mentioned palladium catalyst at 250°C. After the reaction, the liquid components were 6.3% benzene, 53.5% chlorobenzene, 14.9% o-dichlorobenzene, 12.7% m-dichlorobenzene, 12.1% p-dichlorobenzene, and 0.5% 1,2,4-trichlorobenzene, and it operated stably for 3677 hours.

[0089] Example 4 (Diethyl Rhodium Acetate as Precious Metal Precursor)

[0090] 100g of Silicalite-1 pure silicon molecular sieve, 100g of dipropylamine, 500g of methanol and 500g of ethanol were mixed and put into a reactor and reacted at 150°C for 24h. Ethanol was added to the wet solid after the reaction for washing, and then dried at 120°C for 12h to obtain a dried solid. 1g of Pt / C desulfurization catalyst, 800g of xylene and 1000g of hexane were put into a reactor for 36h to obtain a desulfurized xylene and hexane mixed solvent. The dried solid and 0.036g of diethyl rhodium acetate were put into 1800g of desulfurized xylene and hexane mixed solvent and immersed for 2h. The wet solid obtained after impregnation was dried at 80°C for 72h, and then calcined at 350°C in a tubular furnace in an argon atmosphere for 18h to obtain a pure silicon molecular sieve highly dispersed rhodium catalyst.

[0091] A mixed feedstock of 83.8wt% 1,2,4-trichlorobenzene and 16.2wt% hexachlorobenzene is prepared with a mass space velocity of 1h -1A mixed raw material of 1,2,4-trichlorobenzene solution and 16.2wt% hexachlorobenzene was mixed with hydrogen with a hydrogen ratio of 4 at a pressure of 0.8MPa, and a hydrodechlorination reaction occurred in a fixed bed layer containing the above-mentioned rhodium catalyst at 350°C. After the reaction, the liquid components were 4.1% benzene, 73.1% chlorobenzene, 12.3% o-dichlorobenzene, 5.4% m-dichlorobenzene, and 5.1% p-dichlorobenzene, and it operated stably for 3658 hours.

[0092] Example 5 (Tetracarbonyl dirhodium dichloride as a noble metal precursor)

[0093] 100g Silicalite-1 pure silicon molecular sieve, 50g isopropylamine, 2000g methanol, and 2000g ethylene glycol were mixed and put into a reactor and reacted at 80°C for 60h. Ethanol was added to the wet solid after the reaction for washing, and then dried at 100°C for 18h to obtain a dried solid. 1g Pd / C desulfurization catalyst, 400g isopropylbenzene, and 400g octane were put into a reactor for 12h to obtain a desulfurized isopropylbenzene and octane mixed solvent. The dried solid and 0.756g tetracarbonyl dirhodium dichloride were put into 800g desulfurized isopropylbenzene and octane mixed solvent and immersed for 12h. The wet solid obtained after the immersion was dried at 100°C for 48h, and then calcined at 450°C in a tube furnace in an argon atmosphere for 8h to obtain a pure silicon molecular sieve highly dispersed rhodium catalyst.

[0094] Take a polychlorobenzene raw material containing 11.4wt% o-dichlorobenzene, 10.5wt% m-dichlorobenzene, 7.2wt% p-dichlorobenzene, 11.3wt% 1,2,3-trichlorobenzene, 29.7wt% 1,2,4-trichlorobenzene, 8.2wt% 1,3,5-trichlorobenzene, 7.1wt% 1,2,3,5-tetrachlorobenzene, 3.5wt% 1,2,3,4-tetrachlorobenzene, 3.1wt% 1,2,4,5-tetrachlorobenzene, 4.6wt% pentachlorobenzene, 3.4wt% hexachlorobenzene, and the space velocity is 1h -1 The above-mentioned polychlorinated benzene raw material and hydrogen with a hydrogen ratio of 5 are mixed at a pressure of 0.2MPa, and a hydrodechlorination reaction occurs in a fixed bed layer containing the above-mentioned rhodium catalyst at 350°C. The liquid components after the reaction are 5.3% benzene, 85.5% chlorobenzene, 4.7% o-dichlorobenzene, 2.1% m-dichlorobenzene, and 2.4% p-dichlorobenzene. The stable operation lasts for 3194 hours.

[0095] Embodiment 6-9

[0096] The catalyst was prepared according to Example 1 and the obtained catalyst was used to carry out the hydrodechlorination reaction of chlorobenzene, except that the type of pure silicon molecular sieve was changed. The catalyst performance evaluation was as follows:

[0097]

[0098]

[0099] Examples 10-16

[0100] The catalyst was prepared according to Example 1 and the obtained catalyst was used to carry out the hydrodechlorination reaction of chlorobenzene, except that the type of organic amine and / or alcohol was changed. The catalyst performance was evaluated as follows:

[0101]

[0102] Examples 17-25

[0103] The catalyst was prepared according to Example 1 and the obtained catalyst was used to carry out the hydrodechlorination reaction of chlorobenzene, except that the mass ratio of the all-silicon molecular sieve to the organic amine and / or alcohol was changed. The catalyst performance was evaluated as follows:

[0104]

[0105]

[0106] Examples 26-35

[0107] The catalyst was prepared according to Example 1 and the obtained catalyst was used to carry out the hydrodechlorination reaction of chlorobenzene, except that the types of the noble metal precursor and the hydrocarbon solvent were changed. The catalyst performance was evaluated as follows:

[0108]

[0109] Examples 32-38

[0110] The catalyst was prepared according to Example 1 and the obtained catalyst was used to carry out the hydrodechlorination reaction of chlorobenzene, except that the mass ratio of the noble metal precursor and the hydrocarbon solvent was changed. The catalyst performance was evaluated as follows:

[0111]

[0112]

[0113] Examples 39-42

[0114] The catalyst was prepared according to Example 1 and the obtained catalyst was used to carry out the hydrodechlorination reaction of chlorobenzene, except that the reaction parameters of the hydrodechlorination reaction of chlorobenzene were changed. The catalyst performance evaluation was as follows:

[0115]

[0116] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a pure silicon molecular sieve loaded with a noble metal catalyst, the method comprising the following steps: (1) treating pure silicon molecular sieve with an alcohol solution of an organic amine under heating conditions, and obtaining a modified pure silicon molecular sieve through solid-liquid separation, washing, and drying; (2) impregnating the modified pure silicon molecular sieve with a noble metal precursor in a hydrocarbon solvent, performing solid-liquid separation and drying to obtain a catalyst precursor; (3) calcining the catalyst precursor to obtain a pure silicon molecular sieve supported noble metal catalyst, The mass ratio of pure silicon molecular sieve to precious metal is 1:0.00005 to 1:0.005, preferably 1:0.0001 to 1:0.002, and more preferably 1:0.0001 to 1:0.0015.

2. The method according to claim 1, characterized in that The pure silicon molecular sieve is one or more selected from the following group: pure silicon Silicalite-1 molecular sieve, pure silicon Beta molecular sieve, pure silicon MCM-41 molecular sieve, pure silicon SBA-15 molecular sieve, ZSM-5 pure silicon molecular sieve.

3. The method according to claim 1, characterized in that The organic amine is selected from one or more of the following groups: methylamine, dimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, n-propylamine, isopropylamine, dipropylamine and aniline.

4. The method according to claim 1, characterized in that The alcohol is selected from one or more of the following groups: methanol, ethanol, ethylene glycol, n-propanol, isopropanol and glycerol.

5. The method according to claim 1, characterized in that The mass ratio of pure silicon molecular sieve to organic amine is 1:0.05 to 1:15, preferably 1:0.1 to 1:10; and / or The heating temperature in step (1) is 40-200° C., preferably 50-180° C.; and / or The treatment time in step (1) is 0.5-80 hours, preferably 1-72 hours.

6. The method according to claim 1, characterized in that The noble metal is selected from one or more of the following groups: palladium, rhodium, platinum; and / or The noble metal precursor is selected from one or more of noble metal acetates, oxalates, acetylacetonates, alkyl acetates, carbonyl chlorides, alkyl chlorides, benzylidene acetonates, phenylphosphine chlorides, and ethylenediamine chlorides; and / or The hydrocarbon solvent is selected from one or more of the following groups: benzene, toluene, xylene, mesitylene, propylbenzene, isopropylbenzene, octane, cyclohexane, hexane, isohexane, heptane and isoheptane; and / or The mass ratio of the pure silicon molecular sieve to the hydrocarbon solvent is 1:2 to 1:25, preferably 1:5 to 1:

20.

7. The method according to claim 1, characterized in that Before the modified pure silicon molecular sieve is impregnated with a noble metal precursor in a hydrocarbon type solvent, the hydrocarbon type solvent is desulfurized using a desulfurization catalyst.

8. The method according to claim 7, characterized in that The desulfurization catalyst is selected from one or more of the following groups: Pd / C, Pt / C, Pd / Al2O3, Pt / Al2O3 and / or The mass ratio of the desulfurization catalyst to the hydrocarbon solvent is 1:400 to 1:5000, preferably 1:500 to 1:2000.

9. A pure silicon molecular sieve loaded with noble metal catalyst obtained by the method according to any one of claims 1 to 8.

10. A method for hydrodechlorination of chlorobenzene, characterized in that: The method comprises using the pure silicon molecular sieve supported noble metal catalyst as claimed in claim 9.

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