Catalyst, preparation method thereof and method for preparing peroxy acid

Abstract

The invention belongs to the field of catalysts and preparation thereof, and particularly relates to a catalyst, a preparation method thereof and a method for preparing peroxy acid. The catalyst comprises a modified molecular sieve and heteropoly acid loaded on the modified molecular sieve, and the surface of the modified molecular sieve is modified with alkyl and amino. When the catalyst is used for preparing peroxy acid, the conversion rate of organic acid can be increased, the equilibrium conversion rate is higher than 60%, and the selectivity of the prepared peroxy acid is gt; in addition, the catalyst can be recycled, and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the field of catalysts and preparation thereof, in particular to a catalyst and preparation method thereof and a method for preparing peroxyacid, and more particularly to a molecular sieve-supported heteropolyacid catalyst and preparation method thereof and a method for preparing peroxyacid using the catalyst. Background Art

[0002] Peroxy acid is an important organic derivative of hydrogen peroxide. Its typical synthesis method is to react hydrogen peroxide with organic carboxylic acid. Its specific synthesis route is: under the action of an acidic catalyst, 30-90% of hydrogen peroxide and organic carboxylic acid are mixed, and the equilibrium reaction process generates a peroxy acid mixed solution, which contains organic carboxylic acid, hydrogen peroxide, water and catalyst. In the prior art, inorganic acids, acidic ion exchange resins, solid acids and organic sulfonic acids can all be used as catalysts.

[0003] CN105646433A discloses a method for continuously preparing high-purity caprolactone, wherein an organic acid and hydrogen peroxide are introduced into a reaction distillation tower, an oxidation reaction occurs under the catalysis of a strongly acidic cation exchange resin, and water is separated. The organic peroxy acid generated by the reaction enters the reaction distillation tower, and an oxidation reaction occurs with cyclohexanone to prepare a crude caprolactone liquid, which is then separated by distillation to obtain high-purity caprolactone. Using an acidic resin as a catalyst can obtain a higher peroxy acid yield in the initial stage of the reaction, but with long-term operation, the active component sulfonic acid radical on the resin surface is oxidized and lost, resulting in a decrease in catalytic stability, which is not suitable for industrial production.

[0004] CN108863883A discloses a method for preparing anhydrous peroxypropionic acid, which uses 4-5 reaction distillation towers in series, feeds hydrogen peroxide, boric acid catalyst, light components, and phosphate esters, which are premixed and sequentially pumped into the distillation tower body, and the bottom liquid of the last reaction distillation tower enters the distillation distillation tower, and anhydrous peroxypropionic acid without catalyst is extracted at the top of the distillation distillation tower, and the bottom containing catalyst and phosphate ester returns to the initial reactor to complete the cycle. Using the same continuous process, CN110183417A discloses a method for continuously producing caprolactone by catalytic reaction distillation, wherein the concentration section of the reaction distillation tower is used to purify hydrogen peroxide, and the purified hydrogen peroxide and the remaining water-carrying agent are downwardly reacted with acetic acid to generate peracetic acid and water, and the generated water is taken out by the water-carrying agent, and the generated peracetic acid is upwardly transferred after heat exchange, and reacts with cyclohexanone to generate caprolactone and acetic acid. The above two processes use a weak acid catalyst (boric acid) or no acid catalyst to synthesize peracid. Although the yield of caprolactone is high, the yield of the synthesized peracid is low and the reaction time is long. The generated peracid is very easy to decompose, which is not conducive to industrial production.

[0005] In the traditional process, concentrated sulfuric acid is generally used as a catalyst for the synthesis of peroxyacid. Although it can obtain a relatively ideal peroxyacid yield, it is easy to cause the polymerization of caprolactone in the subsequent production, making it poor in selectivity. In addition, concentrated sulfuric acid seriously corrodes the equipment and is difficult to recycle. The post-processing process is complicated and easy to cause environmental pollution. Boric acid is a weak catalyst. Although it generates fewer by-products in the process of preparing caprolactone, its catalytic peroxyacid generation rate is slow and the energy consumption is high, which reduces the production efficiency. Summary of the invention

[0006] The object of the present invention is to solve the problems of the prior art in that when a catalyst is used to prepare peroxyacid, the catalyst has low stability, the yield of the synthesized peroxyacid is low, the selectivity is poor, and it is not conducive to industrial production, thereby providing a catalyst and a preparation method thereof, and a method for preparing peroxyacid using the catalyst. The present invention adopts heteropolyacid as an active component, and adopts a molecular sieve modified with an alkyl group and an amino group as a carrier, so that the heteropolyacid can be more firmly loaded on the carrier, thereby improving the conversion rate of organic acid and the yield and selectivity of the peroxyacid when the catalyst is used to prepare the peroxyacid, and the catalyst can be recycled and reused, and is suitable for industrial production.

[0007] The first aspect of the present invention provides a catalyst, which includes a modified molecular sieve and a heteropolyacid loaded on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with alkyl and amino groups, the alkyl and amino groups respectively react with the hydroxyl groups on the surface of the molecular sieve and bond to the surface of the molecular sieve, wherein the anion of the heteropolyacid reacts with the amino group and is anchored to the surface of the molecular sieve.

[0008] Preferably, based on the total weight of the catalyst being 100 weight %, the content of the heteropoly acid is 10-80 weight %, and the content of the modified molecular sieve is 20-90 weight %.

[0009] Preferably, the heteropoly acid is selected from one or more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid.

[0010] Preferably, the molecular sieve in the modified molecular sieve is a mesoporous molecular sieve and / or a porous molecular sieve.

[0011] Preferably, the mesoporous molecular sieve is one or more of SBA-15 molecular sieve, MCM-41 molecular sieve and KIT-6 molecular sieve.

[0012] Preferably, the porous molecular sieve is one or more selected from porous MFI molecular sieve, porous MEL molecular sieve and porous MOR molecular sieve.

[0013] The second aspect of the present invention provides a method for preparing a catalyst, the method comprising the following steps:

[0014] (1) Alkyl modification: reacting a molecular sieve, an alkoxysilane and a first organic solvent;

[0015] (2) Amino modification: reacting the reaction product obtained in step (1), aminooxysilane and a second organic solvent;

[0016] (3) Loading heteropoly acid: calcining the heteropoly acid, and then mixing the calcined product, the third organic solvent and the reaction product obtained in step (2).

[0017] Preferably, the molecular sieve is a mesoporous molecular sieve and / or a porous molecular sieve. More preferably, the mesoporous molecular sieve is selected from one or more of SBA-15 molecular sieve, MCM-41 molecular sieve and KIT-6 molecular sieve. Further preferably, the porous molecular sieve is selected from one or more of porous MFI molecular sieve, porous MEL molecular sieve and porous MOR molecular sieve.

[0018] Preferably, the heteropoly acid is selected from one or more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid.

[0019] Preferably, the alkoxysilane is trimethoxysilane and / or n-octyltriethoxysilane.

[0020] Preferably, the aminooxysilane is selected from one or more of 3-aminotrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and anilinomethyltriethoxysilane.

[0021] Preferably, in step (1), the molecular sieve, the alkoxysilane and the first organic solvent are used in a ratio of 1 g: 2-5 mL: 5-12 mL.

[0022] Preferably, the molecular sieve in step (1), the aminooxysilane in step (2) and the second organic solvent are used in a ratio of 1:2-5 g / mL:5-12 g / mL.

[0023] Preferably, the ratio of the molecular sieve in step (1) to the heteropoly acid in step (3) is 0.25-9:1.

[0024] Preferably, the first organic solvent and the second organic solvent are independently selected from one or more of toluene, methanol, acetonitrile and dichloromethane.

[0025] Preferably, the third organic solvent is selected from one or more of ethanol, methanol, acetone and n-hexane.

[0026] Preferably, in step (1), the reaction conditions include: temperature of 25-60° C., and time of 0.5-5 h.

[0027] Preferably, in step (2), the reaction conditions include: temperature of 25-60° C., and time of 0.5-5 h.

[0028] The third aspect of the present invention provides a method for preparing peroxy acid, which comprises: reacting the above-mentioned catalyst with an organic acid and hydrogen peroxide at 25-55°C.

[0029] Preferably, the flow rate of the organic acid is 0.5-10 mL / min, and the flow rate of the hydrogen peroxide is 0.5-10 mL / min. More preferably, the concentration of the hydrogen peroxide is 30-70% by weight.

[0030] Preferably, the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, benzoic acid and m-chlorobenzoic acid.

[0031] In the catalyst of the present invention, the heteropoly acid is loaded on the molecular sieve modified with alkyl and amino groups, so that the advantages of the heteropoly acid such as high catalytic activity, good selectivity, mild catalytic conditions and environmental friendliness can be combined with the characteristic of the molecular sieve that it is conducive to the diffusion of reactants and peroxyacid molecules. At the same time, the loading firmness of the heteropoly acid can be enhanced after modification with alkyl and amino groups. Therefore, when the catalyst of the present invention is used to prepare peroxyacid, the conversion efficiency of the organic acid can be improved, and a peroxyacid product with high yield and high selectivity can be obtained. The catalyst can be recycled and reused, is environmentally friendly, and is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a scanning electron micrograph of the catalyst of phosphotungstic acid loaded on SBA-15 modified with alkylamino groups prepared in Example 1 of the present invention;

[0033] Figure 2 This is an infrared spectrum of the catalyst of phosphotungstic acid loaded on SBA-15 modified with alkylamino groups prepared in Example 1 of the present invention;

[0034] Figure 3 This is a scanning electron microscopic image of the amino-modified SBA-15 loaded with phosphotungstic acid catalyst prepared in Comparative Example 1 of the present invention;

[0035] Figure 4 This is the infrared spectrum of the catalyst of amino-modified SBA-15 loaded with phosphotungstic acid prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0037] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0038] Scholars at home and abroad have prepared peroxyacids from organic acids under the action of acidic ion exchange resins, molecular sieves, heteropolyacids and composite metal oxides. Heteropolyacids, as solid acid catalysts, are a class of environmentally friendly catalytic materials with excellent performance. They are not easy to decompose under strong oxidizing conditions, have the advantages of high catalytic activity, good selectivity, and mild catalytic conditions. They can replace concentrated sulfuric acid and nitric acid in a series of fine syntheses to meet environmental protection requirements. Although heteropolyacids have many advantages, they are soluble in polar solvents and cause recycling difficulties. Therefore, the development of porous hydrophobic solid acid efficient catalysts based on heteropolyacids for the synthesis of peroxyacids is the key to solving the above problems. Based on this, the inventors of the present invention have completed the following inventions.

[0039] The first aspect of the present invention provides a catalyst, which includes a modified molecular sieve and a heteropoly acid loaded on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with an alkyl group and an amino group, specifically, the alkyl group and the amino group act with the hydroxyl group on the surface of the molecular sieve, respectively, and are bonded to the surface of the molecular sieve, wherein the anion of the heteropoly acid acts with the amino group and is anchored to the surface of the molecular sieve. In this article, "anchoring" refers to the strong interaction between the heteropoly acid and the molecular sieve.

[0040] In the catalyst of the present invention, in a specific embodiment, the heteropoly acid is selected from one or more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid.

[0041] In the catalyst of the present invention, in a specific embodiment, the molecular sieve in the modified molecular sieve is a mesoporous molecular sieve and / or a porous molecular sieve.

[0042] In the catalyst of the present invention, in a preferred embodiment, the mesoporous molecular sieve is selected from one or more of SBA-15 molecular sieve, MCM-41 molecular sieve and KIT-6.

[0043] In the catalyst of the present invention, in a specific embodiment, the SiO2 / Al2O3 molar ratio of the porous molecular sieve is 100-500, and the specific surface area is 50-600m 2 / g, pore volume is 0.1-1.5mL / g, specifically, the porous molecular sieve is derived from a microporous molecular sieve. In a preferred embodiment, the porous molecular sieve is selected from one or more of porous MFI molecular sieve, porous MEL molecular sieve and porous MOR molecular sieve.

[0044] In the catalyst of the present invention, in a specific embodiment, based on the total weight of the catalyst as 100 weight%, the content of the heteropolyacid is 10-80 weight%, for example, it can be 10 weight%, 20 weight%, 30 weight%, 40 weight%, 50 weight%, 60 weight%, 70 weight% or 80 weight%, and the content of the modified molecular sieve is 20-90 weight%, for example, it can be 20 weight%, 30 weight%, 40 weight%, 50 weight%, 60 weight%, 70 weight%, 80 weight% or 90 weight%.

[0045] According to a first specific embodiment of the catalyst of the present invention, the catalyst comprises a modified molecular sieve and a heteropolyacid loaded on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with an alkyl group and an amino group, the alkyl group and the amino group respectively react with the hydroxyl group on the surface of the molecular sieve and bond to the surface of the molecular sieve, wherein the anion of the heteropolyacid reacts with the amino group and is anchored to the surface of the molecular sieve.

[0046] According to a second specific embodiment of the catalyst of the present invention, the catalyst comprises a modified molecular sieve and a heteropoly acid loaded on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with an alkyl group and an amino group, the alkyl group and the amino group respectively react with the hydroxyl group on the surface of the molecular sieve and bond to the surface of the molecular sieve, wherein the anion of the heteropoly acid reacts with the amino group and is anchored to the surface of the molecular sieve; based on the total weight of the catalyst as 100 weight%, the content of the heteropoly acid is 10-80 weight%, and the content of the modified molecular sieve is 20-90 weight%.

[0047] According to a third specific embodiment of the catalyst of the present invention, the catalyst comprises a modified molecular sieve and a heteropolyacid loaded on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with an alkyl group and an amino group, the alkyl group and the amino group respectively react with the hydroxyl group on the surface of the molecular sieve and bond to the surface of the molecular sieve, wherein the anion of the heteropolyacid reacts with the amino group and is anchored to the surface of the molecular sieve; based on the total weight of the catalyst as 100 weight%, the content of the heteropolyacid is 10-80 weight%, and the content of the modified molecular sieve is 20-90 weight%; the heteropolyacid is selected from one or more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid.

[0048] According to a fourth specific embodiment of the catalyst of the present invention, the catalyst comprises a modified molecular sieve and a heteropolyacid loaded on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with an alkyl group and an amino group, the alkyl group and the amino group respectively react with the hydroxyl group on the surface of the molecular sieve and bond to the surface of the molecular sieve, wherein the anion of the heteropolyacid reacts with the amino group and is anchored to the surface of the molecular sieve; based on the total weight of the catalyst as 100 weight%, the content of the heteropolyacid is 10-80 weight%, and the content of the modified molecular sieve is 20-90 weight%; the heteropolyacid is selected from one or more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid; the molecular sieve in the modified molecular sieve is a mesoporous molecular sieve and / or a porous molecular sieve.

[0049] According to a fifth specific embodiment of the catalyst of the present invention, the catalyst comprises a modified molecular sieve and a heteropoly acid loaded on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with an alkyl group and an amino group, the alkyl group and the amino group respectively react with the hydroxyl group on the surface of the molecular sieve and bond to the surface of the molecular sieve, wherein the anion of the heteropoly acid reacts with the amino group and is anchored on the surface of the molecular sieve; based on the total weight of the catalyst as 100 weight %, the content of the heteropoly acid is 10-80 weight %, and the content of the modified molecular sieve is 20-90 weight %; the heteropoly acid is selected from one or more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid; the molecular sieve in the modified molecular sieve is a mesoporous molecular sieve and / or a porous molecular sieve; the mesoporous molecular sieve is selected from one or more of SBA-15 molecular sieve, MCM-41 molecular sieve and CMK-1 molecular sieve, and the porous molecular sieve is selected from one or more of porous MFI molecular sieve, porous MEL molecular sieve and porous MOR molecular sieve.

[0050] The second aspect of the present invention provides a method for preparing a catalyst, the method comprising the following steps:

[0051] (1) Alkyl modification: reacting a molecular sieve, an alkoxysilane and a first organic solvent;

[0052] (2) Amino modification: reacting the reaction product obtained in step (1), aminooxysilane and a second organic solvent;

[0053] (3) Loading heteropoly acid: calcining the heteropoly acid, and then mixing the calcined product, the third organic solvent and the reaction product obtained in step (2).

[0054] In the method of the present invention, in a specific embodiment, the molecular sieve is a mesoporous molecular sieve and / or a porous molecular sieve.

[0055] In the method of the present invention, in a preferred embodiment, the mesoporous molecular sieve is selected from one or more of SBA-15 molecular sieve, MCM-41 molecular sieve and KIT-6 molecular sieve.

[0056] In the method of the present invention, in a specific embodiment, the SiO2 / Al2O3 molar ratio of the porous molecular sieve is 100-500, and the specific surface area is 50-600m 2 / g, pore volume is 0.1-1.5mL / g, specifically, the porous molecular sieve is derived from a microporous molecular sieve. In a preferred embodiment, the porous molecular sieve is selected from one or more of porous MFI molecular sieve, porous MEL molecular sieve and porous MOR molecular sieve.

[0057] In the method of the present invention, in a specific embodiment, the alkoxysilane is trimethoxysilane and / or n-octyltriethoxysilane.

[0058] In the method of the present invention, in a specific embodiment, the first organic solvent is selected from one or more of toluene, methanol, acetonitrile and dichloromethane.

[0059] In the method of the present invention, in a specific embodiment, in step (1), the usage ratio of the molecular sieve, the alkoxysilane and the first organic solvent is 1g:2-5mL:5-12mL, for example, it can be 1g:2mL:5mL, 1g:3.33mL:8.33mL, 1g:4mL:10mL or 1g:5mL:12mL.

[0060] In the method of the present invention, in a specific embodiment, in step (1), the reaction is carried out under stirring. In a preferred embodiment, in step (1), the reaction conditions include: a temperature of 25-60°C, such as 25°C, 35°C, 45°C or 60°C, and a time of 0.5-5h, such as 0.5h, 1h, 2h, 3h, 4h or 5h.

[0061] In the method of the present invention, in a specific embodiment, in step (1), the method further comprises filtering, washing and drying the product obtained in the reaction of step (1).

[0062] In the method of the present invention, in a specific embodiment, in step (1), the filtration is performed under a protective atmosphere. In a preferred embodiment, the protective atmosphere is argon, nitrogen or helium.

[0063] In the method of the present invention, in a specific embodiment, in step (1), an organic solvent is used for washing; in a preferred embodiment, the organic solvent is toluene and / or methanol.

[0064] In the method of the present invention, in a specific embodiment, in step (1), drying is performed under vacuum conditions.

[0065] In the method of the present invention, in a specific embodiment, in step (2), the aminooxysilane is selected from one or more of 3-aminotrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and anilinemethyltriethoxysilane.

[0066] In the method of the present invention, in a specific embodiment, the second organic solvent is selected from one or more of toluene, methanol, acetonitrile and dichloromethane.

[0067] In the method of the present invention, in a specific embodiment, the usage ratio of the molecular sieve in step (1), the aminooxysilane in step (2) and the second organic solvent is 2-5mL:5-12mL, for example, it can be 1g:2mL:5mL, 1g:3.33mL:8.33mL, 1g:4mL:10mL or 1g:5mL:12mL.

[0068] In the method of the present invention, in a specific embodiment, in step (2), the reaction is carried out under stirring. In a preferred embodiment, in step (2), the reaction conditions include: a temperature of 25-60°C, such as 25°C, 35°C, 45°C or 60°C, and a time of 0.5-5h, such as 0.5h, 1h, 2h, 3h, 4h or 5h.

[0069] In the method of the present invention, in a specific embodiment, in step (2), the method further comprises filtering, washing and drying the product obtained in the reaction of step (2).

[0070] In the method of the present invention, in a specific embodiment, in step (2), the filtration is performed under a protective atmosphere. In a preferred embodiment, the protective atmosphere is argon, nitrogen or helium.

[0071] In the method of the present invention, in a specific embodiment, in step (2), an organic solvent is used for washing; in a preferred embodiment, the organic solvent is toluene and / or methanol.

[0072] In the method of the present invention, in a specific embodiment, in step (2), drying is performed under vacuum conditions.

[0073] In the method of the present invention, in a specific embodiment, in step (3), the heteropoly acid is selected from one or more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid.

[0074] In the method of the present invention, in order to better load the heteropolyacid, the heteropolyacid needs to be activated first. Specifically, the activation method is calcination. In a specific embodiment, in step (3), the calcination conditions include: temperature of 300-400°C and time of 0.5-5h.

[0075] In the method of the present invention, in a specific embodiment, in step (3), the third organic solvent is selected from one or more of ethanol, methanol, acetone and n-hexane.

[0076] In the method of the present invention, the heteropoly acid is loaded on the surface of the carrier by an excess impregnation method. In step (3), in a specific operation, the calcined product is dispersed in the third organic solvent, and the reaction product obtained in step (2) is added and mixed to completely immerse it.

[0077] In the method of the present invention, in a specific embodiment, the usage ratio of the molecular sieve in step (1) to the heteropoly acid in step (3) is 0.25-9:1, for example, it can be 0.25:1, 2.4:1, 5:1, 7:1 or 9:1.

[0078] In the method of the present invention, in a specific embodiment, in step (3), the mixing is performed under stirring conditions. In a preferred embodiment, in step (3), the mixing conditions include: a temperature of 10-35°C, a stirring speed of 100-500 rpm, and a time of 3-10 hours.

[0079] In the method of the present invention, in a specific embodiment, in step (3), the method further comprises filtering, washing and drying the product obtained by mixing in step (3).

[0080] In the method of the present invention, in a specific embodiment, in step (3), the washing conditions include: the number of washes is 2-4 times, and the washing solution is ethanol and / or water.

[0081] In the method of the present invention, in a specific embodiment, in step (3), the drying conditions include: temperature of 100-120° C., time of 5-10 h.

[0082] The third aspect of the present invention provides a method for preparing peroxy acid, which comprises: reacting the above-mentioned catalyst with an organic acid and hydrogen peroxide at 25-55°C.

[0083] In the method of the present invention, in the specific operation process, the above-mentioned catalyst is first mixed and diluted with quartz sand and placed in the reaction device, and then organic acid is pumped into the reaction device. After the temperature reaches 25-55°C, hydrogen peroxide is pumped into the reaction device.

[0084] In the method of the present invention, in a specific embodiment, the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, benzoic acid and m-chlorobenzoic acid. In a preferred embodiment, the flow rate of the organic acid is 0.5-10 mL / min.

[0085] In the method of the present invention, in a specific embodiment, the reaction device can be a fixed bed reactor, a suspended bed reactor, a tank reactor or a micro-reactor.

[0086] In the method of the present invention, in a specific embodiment, the concentration of the hydrogen peroxide is 30-70% by weight, and the flow rate is 0.5-10 mL / min.

[0087] The catalyst of the present invention is further described below by way of examples. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following examples.

[0088] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0089] SBA-15 molecular sieve: The manufacturer is Xianfeng Nanomaterial Technology Co., Ltd., the brand is 100553, and the pore size is 6-11nm.

[0090] MCM-41 molecular sieve: The manufacturer is Xianfeng Nanomaterial Technology Co., Ltd., the brand is 100555, and the pore size is 3-5nm.

[0091] KIT-6 molecular sieve: The manufacturer is Xianfeng Nanomaterial Technology Co., Ltd., the brand is 100557, and the pore size is 3-7nm.

[0092] Porous MFI molecular sieve: The manufacturer is Nankai Catalyst Factory, customized, SiO2 / Al2O3 molar ratio is 200, specific surface area is 460m 2 / g, and the pore volume is 0.55mL / g.

[0093] Porous MEL molecular sieve: homemade, SiO2 / Al2O3 molar ratio is 220, specific surface area is 520m 2 / g, and the pore volume is 0.60mL / g.

[0094] Porous MOR molecular sieve: The manufacturer is Nankai Catalyst Factory, customized, SiO2 / Al2O3 molar ratio is 200, specific surface area is 450m 2 / g, and the pore volume is 0.45mL / g.

[0095] Trimethoxysilane: The manufacturer is Wokai Reagent, the brand number is XW010045.

[0096] n-Octyltriethoxysilane: The manufacturer is TCI Chemical Reagents, the brand number is TO0171100ML.

[0097] Test Case

[0098] Mass concentration of peroxyacid: The analysis method of peroxyacid refers to the national standard "Peracetic acid solution GB / T19104-2021".

[0099]

[0100] Where C(Na2S2O3) and V(Na2S2O3) are the concentration and volume of sodium thiosulfate standard solution, in mol / L and ml respectively; M(RCOOOH) is the molar mass of peracid, and ms is the sample mass.

[0101] According to the above national standard test method, the mass of peroxyacid in the system liquid is obtained. The amount of hydrogen peroxide added is known, and based on the following reaction equation, the organic acid conversion rate, peroxyacid selectivity and peroxyacid yield can be calculated.

[0102] RCOOH+H2O2→RCOOOH+H2O

[0103] Conversion rate of organic acid:

[0104]

[0105] n is the molar amount of the substance; the equilibrium conversion rate is the organic acid conversion rate corresponding to the reaction reaching equilibrium.

[0106] Selectivity of peroxyacids:

[0107]

[0108] Yield of peroxyacid:

[0109] Y(RCOOOH)=X(RCOOH)×S(RCOOOH).

[0110] Example 1

[0111] The method for preparing the catalyst comprises the following steps:

[0112] (1) Alkyl modification: 12 g of SBA-15 molecular sieve was weighed and placed in a single-necked flask, 100 mL of toluene was added, and then 40 mL of trimethoxysilane was dropped into the mixture under magnetic stirring to mix, and the obtained mixed product was condensed and refluxed at 45 ° C for 4 h, and then the condensed product was filtered under argon, and the solid phase product obtained by filtration was washed with toluene and methanol, and finally vacuum dried;

[0113] (2) Amino modification: The dried product obtained in step (1) was placed in a single-necked flask, 100 mL of toluene was added, and then 45 mL of 3-aminotrimethoxysilane was added dropwise under magnetic stirring to mix, the obtained mixed product was condensed and refluxed at 45° C. and stirred for 4 h, and then the condensed product was filtered under argon, and the solid phase product obtained by filtration was washed with toluene and methanol, and finally vacuum dried;

[0114] (3) Loading heteropolyacid: Weigh 5 g of phosphotungstic acid and calcine at 350° C. for 3 h for activation. Disperse the calcined product in 100 mL of ethanol solvent for the first mixing. Then, mix the product after the first mixing with the dry product obtained in step (2) for a second time at 25° C. and 200 rpm for 6 h. Centrifuge the product after the second mixing, wash with water 3 times, and finally dry at 110° C. for 10 h.

[0115] The method for preparing peroxyacid comprises:

[0116] 3 g of the catalyst prepared in Example 1 was weighed, and 3 g of quartz sand was mixed with the catalyst and diluted, and then loaded into a fixed bed reactor, and then propionic acid was pumped into the fixed bed reactor at a flow rate of 1.5 mL / min. After the temperature reached 55° C., hydrogen peroxide (concentration of 50 weight %) was finally pumped into the fixed bed reactor at a flow rate of 0.8 mL / min for reaction, and samples were collected at the outlet of the reaction solution for analysis, and the concentration of peroxypropionic acid was analyzed every 30 min. After 3 h, the equilibrium conversion rate of the organic acid reached 68.5%, the concentration of the prepared peroxy acid was 15.3%, the yield was 67.1%, and the selectivity was 98.5%.

[0117] Example 2

[0118] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that the SBA-15 molecular sieve is replaced by a porous MFI type molecular sieve.

[0119] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 2. After 3 hours, the equilibrium conversion rate of the organic acid reached 72.2%, the concentration of the prepared peroxy acid was 15.8%, the yield was 71.2%, and the selectivity was 98.6%.

[0120] Example 3

[0121] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that the SBA-15 molecular sieve is replaced by the MCM-41 molecular sieve.

[0122] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 3. After 3 hours, the equilibrium conversion rate of the organic acid reached 71.3%, the concentration of the prepared peroxy acid was 15.3%, the yield was 70.0%, and the selectivity was 98.2%.

[0123] Example 4

[0124] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that the SBA-15 molecular sieve is replaced by a KIT-6 molecular sieve.

[0125] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 4. After 3 hours, the conversion rate of the organic acid reached 69.8%, the concentration of the prepared peroxy acid was 14.8%, the yield was 68.5%, and the selectivity was 98.2%.

[0126] Example 5

[0127] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that the SBA-15 molecular sieve is replaced by a porous MEL type molecular sieve.

[0128] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 5. After 3 hours, the equilibrium conversion rate of the organic acid reached 73.6%, the concentration of the prepared peroxy acid was 15.8%, the yield was 72.5%, and the selectivity was 98.5%.

[0129] Example 6

[0130] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that the SBA-15 molecular sieve is replaced by a porous MOR molecular sieve.

[0131] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 6. After 3 hours, the conversion rate of the organic acid reached 66.2%, the concentration of the prepared peroxy acid was 13.9%, the yield was 64.5%, and the selectivity was 98.5%.

[0132] Example 7

[0133] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that phosphotungstic acid is replaced by phosphomolybdic acid.

[0134] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 7. After 3 hours, the equilibrium conversion rate of the organic acid reached 68.7%, the concentration of the prepared peroxy acid was 13.4%, the yield was 57.6%, and the selectivity was 98.1%.

[0135] Example 8

[0136] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that phosphotungstic acid is replaced by silicotungstic acid.

[0137] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 8. After 3 hours, the equilibrium conversion rate of the organic acid reached 65.2%, the concentration of the prepared peroxy acid was 13.2%, the yield was 54.3%, and the selectivity was 98.3%.

[0138] Example 9

[0139] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that in step (1), trimethoxysilane is replaced by n-octyltriethoxysilane.

[0140] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 9. After 3 hours, the conversion rate of the organic acid reached 69.3%, the concentration of the prepared peroxy acid was 15.5%, the yield was 68.1%, and the selectivity was 98.3%.

[0141] Example 10

[0142] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that in step (2), 3-aminotrimethoxysilane is replaced by 3-aminopropyltriethoxysilane.

[0143] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 10. After 3 hours, the equilibrium conversion rate of the organic acid reached 66.2%, the concentration of the prepared peroxy acid was 14.8%, the yield was 65.1%, and the selectivity was 98.3%.

[0144] Embodiment 11

[0145] The method for preparing the catalyst is implemented in the manner of Example 1, except that in step (1), 12 g of SBA-15 molecular sieve is weighed and placed in a single-necked flask, 100 mL of toluene is added, and then 60 mL of trimethoxysilane is dropped into it under magnetic stirring for mixing.

[0146] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 11. After 3 hours, the equilibrium conversion rate of the organic acid reached 68.8%, the concentration of the prepared peroxy acid was 15.3%, the yield was 67.7%, and the selectivity was 98.4%.

[0147] Example 12

[0148] The method for preparing the catalyst is implemented in the manner of Example 1, except that in step (1), 12 g of SBA-15 molecular sieve is weighed and placed in a single-necked flask, 100 mL of toluene is added, and then 24 mL of trimethoxysilane is dropped into the flask under magnetic stirring for mixing.

[0149] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 12. After 3 hours, the equilibrium conversion rate of the organic acid reached 65.2%, the concentration of the prepared peroxy acid was 13.7%, the yield was 64.0%, and the selectivity was 98.2%.

[0150] Example 13

[0151] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that in step (2), the dried product obtained in step (1) is placed in a single-necked flask, 100 mL of toluene is added, and then 60 mL of 3-aminotrimethoxysilane is dropped into the flask under magnetic stirring for mixing.

[0152] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Example 13. After 3 hours, the equilibrium conversion rate of the organic acid reached 68.2%, the concentration of the prepared peroxy acid was 15.1%, the yield was 66.9%, and the selectivity was 98.1%.

[0153] Embodiment 14

[0154] The method for preparing the catalyst comprises the following steps:

[0155] (1) Alkyl modification: 12 g of SBA-15 molecular sieve was weighed and placed in a single-necked flask, 100 mL of acetonitrile was added, and then 40 mL of trimethoxysilane was dropped into the mixture under magnetic stirring to mix, the obtained mixed product was condensed and refluxed at 25 °C for 1 h, and then the condensed product was filtered under argon, and the solid phase product obtained by filtration was washed with toluene and methanol, and finally vacuum dried;

[0156] (2) Amino modification: The dried product obtained in step (1) was placed in a single-necked flask, 100 mL of dichloromethane was added, and then 45 mL of 3-aminotrimethoxysilane was added dropwise under magnetic stirring to mix, the obtained mixed product was condensed and refluxed at 60° C. and stirred for 5 h, and then the condensed product was filtered under argon, and the solid phase product obtained by filtration was washed with toluene and methanol, and finally vacuum dried;

[0157] (3) Loading heteropolyacid: Weigh 5 g of phosphotungstic acid and calcine at 300° C. for 3 h for activation. Disperse the calcined product in 100 mL of ethanol solvent for the first mixing. Then, mix the product after the first mixing with 5 g of the dried product obtained in step (2) for a second time at 25° C. and 200 rpm for 6 h. Centrifuge the product after the second mixing, wash with water 3 times, and finally dry at 120° C. for 6 h.

[0158] The method for preparing peroxyacid comprises:

[0159] 3 g of the catalyst prepared in Example 14 was weighed, and 3 g of quartz sand was mixed with the catalyst and diluted, and then loaded into a fixed bed reactor, and then propionic acid was pumped into the fixed bed reactor at a flow rate of 1.5 mL / min. After the temperature reached 55° C., hydrogen peroxide (concentration of 50 weight %) was finally pumped into the fixed bed reactor at a flow rate of 0.8 mL / min for reaction, and samples were collected at the outlet of the reaction solution for analysis, and the concentration of peroxypropionic acid was analyzed every 30 min. After 3 h, the equilibrium conversion rate of the organic acid reached 67.7%, the concentration of the prepared peroxy acid was 15.5%, the yield was 49.5%, and the selectivity was 98.8%.

[0160] Comparative Example 1

[0161] The method for preparing the catalyst is implemented in the manner of Example 1, except that the alkyl modification in step (1) is not performed, and the SBA-15 molecular sieve is directly subjected to the amino modification in step (2) and the loading of heteropoly acid in step (3).

[0162] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Comparative Example 1. After 3 hours, the equilibrium conversion rate of the organic acid reached 48.3%, the concentration of the prepared peroxy acid was 12.8%, the yield was 39.9%, and the selectivity was 82.6%.

[0163] Comparative Example 2

[0164] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that the amino modification in step (2) is not performed, and the alkyl-modified product is directly loaded with a heteropolyacid.

[0165] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Comparative Example 2. After 3 hours, the equilibrium conversion rate of the organic acid reached 33.7%, the concentration of the prepared peroxy acid was 9.4%, the yield was 22.5%, and the selectivity was 66.9%.

[0166] Comparative Example 3

[0167] The method for preparing the catalyst is implemented in the same manner as in Example 1, except that the heteropoly acid in step (3) is replaced by boric acid.

[0168] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Comparative Example 3. After 3 hours, the conversion rate of the organic acid reached 5.7%, the concentration of the prepared peroxy acid was 2.1%, the yield was 4.6%, and the selectivity was 81.1%.

[0169] Comparative Example 4

[0170] The method for preparing the catalyst was implemented in the same manner as in Example 1, except that 12 g of SBA-15 molecular sieve was replaced with CMK-3 (ordered mesoporous carbon material).

[0171] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Comparative Example 4. After 3 hours, the equilibrium conversion rate of the organic acid reached 32.3%, the concentration of the prepared peroxy acid was 9.8%, the yield was 24.4%, and the selectivity was 76.4%.

[0172] Comparative Example 5

[0173] The method for preparing the catalyst is implemented in the manner of Example 1, except that the molecular sieve is firstly amino-modified, then the amino-modified molecular sieve is alkyl-modified, and finally the amino- and alkyl-modified molecular sieve is loaded with heteropoly acid.

[0174] The method for preparing peroxy acid was implemented in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced by the catalyst prepared in Comparative Example 5. After 3 hours, the equilibrium conversion rate of the organic acid reached 58.4%, the concentration of the prepared peroxy acid was 14.4%, the yield was 54.0%, and the selectivity was 92.5%.

[0175] When the catalyst of the present invention is used to prepare peroxyacid, the equilibrium conversion rate of organic acid can be increased, the equilibrium conversion rate is greater than 60%, the selectivity is greater than 98%, and the catalyst can be recycled and reused, and is suitable for industrial production.

[0176] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A catalyst, characterized in that The catalyst comprises a modified molecular sieve and a heteropoly acid loaded on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with an alkyl group and an amino group, the alkyl group and the amino group respectively react with the hydroxyl group on the surface of the molecular sieve and bond to the surface of the molecular sieve, wherein the anion of the heteropoly acid reacts with the amino group and is anchored on the surface of the molecular sieve.

2. The catalyst according to claim 1, characterized in that Based on the total weight of the catalyst being 100 weight percent, the content of the heteropoly acid is 10-80 weight percent, and the content of the modified molecular sieve is 20-90 weight percent.

3. The catalyst according to claim 1 or 2, characterized in that The heteropoly acid is selected from one or more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid.

4. The catalyst according to any one of claims 1 to 3, characterized in that The molecular sieve in the modified molecular sieve is a mesoporous molecular sieve and / or a porous molecular sieve.

5. The catalyst according to claim 4, characterized in that The mesoporous molecular sieve is selected from one or more of SBA-15 molecular sieve, MCM-41 molecular sieve and KIT-6 molecular sieve; Preferably, the porous molecular sieve is one or more selected from porous MFI molecular sieve, porous MEL molecular sieve and porous MOR molecular sieve.

6. A method for preparing a catalyst, characterized in that: The method comprises the following steps: (1) Alkyl modification: reacting a molecular sieve, an alkoxysilane and a first organic solvent; (2) Amino modification: reacting the reaction product obtained in step (1), aminooxysilane and a second organic solvent; (3) Loading heteropoly acid: calcining the heteropoly acid, and then mixing the calcined product, the third organic solvent and the reaction product obtained in step (2).

7. The method according to claim 6, characterized in that The molecular sieve is a mesoporous molecular sieve and / or a porous molecular sieve.

8. The method according to claim 7, characterized in that The mesoporous molecular sieve is selected from one or more of SBA-15 molecular sieve, MCM-41 molecular sieve and KIT-6 molecular sieve; Preferably, the porous molecular sieve is one or more selected from porous MFI molecular sieve, porous MEL molecular sieve and porous MOR molecular sieve.

9. The method according to any one of claims 6 to 8, characterized in that: The heteropoly acid is selected from one or more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid.

10. The method according to any one of claims 6 to 9, characterized in that: The alkoxysilane is trimethoxysilane and / or n-octyltriethoxysilane; Preferably, the aminooxysilane is selected from one or more of 3-aminotrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and anilinomethyltriethoxysilane.

11. The method according to any one of claims 6 to 10, characterized in that: In step (1), the molecular sieve, the alkoxysilane and the first organic solvent are used in a ratio of 1 g: 2-5 mL: 5-12 mL; Preferably, the molecular sieve in step (1), the aminooxysilane in step (2) and the second organic solvent are used in a ratio of 1 g: 2-5 mL: 5-12 mL.

12. The method according to any one of claims 6 to 11, characterized in that: The usage ratio of the molecular sieve in step (1) to the heteropoly acid in step (3) is 0.25-9:

1.

13. The method according to any one of claims 6 to 12, characterized in that: The first organic solvent and the second organic solvent are each independently selected from one or more of toluene, methanol, acetonitrile and dichloromethane; Preferably, the third organic solvent is selected from one or more of ethanol, methanol, acetone and n-hexane.

14. The method according to any one of claims 6 to 13, characterized in that: In step (1), the reaction conditions include: temperature of 25-60°C and time of 0.5-5h; Preferably, in step (2), the reaction conditions include: temperature of 25-60° C., and time of 0.5-5 h.

15. A method for preparing a peroxy acid, characterized in that: The method comprises: reacting the catalyst described in any one of claims 1 to 5 or 6 to 14 with an organic acid and hydrogen peroxide at 25 to 55°C.

16. The method according to claim 15, characterized in that The flow rate of the organic acid is 0.5-10 mL / min, and the flow rate of the hydrogen peroxide is 0.5-10 mL / min; Preferably, the concentration of the hydrogen peroxide is 30-70% by weight.

17. The method according to claim 15 or 16, characterized in that The organic acid is selected from one or more of formic acid, acetic acid, propionic acid, benzoic acid and m-chlorobenzoic acid.

Images