A catalyst and method of preparation and method of preparing a peroxy acid

Abstract

The application belongs to the field of catalysts and preparation thereof, and particularly relates to a catalyst, a preparation method and a method for preparing peroxy acid. The catalyst comprises modified molecular sieves and heteropoly acid supported on the modified molecular sieves, wherein the surface of the modified molecular sieves is modified with alkyl and amino groups. When the catalyst is used to prepare peroxy acid, the conversion rate of organic acid can be improved, the equilibrium conversion rate is higher than 60%, the selectivity of the prepared peroxy acid is higher than 98%, and the catalyst can be recycled and reused, and is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysts and their preparation, in particular to a catalyst and a preparation method and a method for preparing peroxy acid, more particularly to a molecular sieve loaded heteropoly acid type catalyst and a preparation method thereof and a method for preparing peroxy acid using the catalyst. BACKGROUND

[0002] Peroxy acid is an important organic derivative of hydrogen peroxide. A typical synthesis method thereof is to react hydrogen peroxide with organic carboxylic acid. The specific synthesis route is as follows: under the action of an acidic catalyst, hydrogen peroxide with a mass fraction of 30-90% is mixed with organic carboxylic acid to generate a peroxy acid mixed solution containing organic carboxylic acid, hydrogen peroxide, water and a catalyst through a balanced reaction process. In the prior art, inorganic acid, acidic ion exchange resin, solid acid and organic sulfonic acid can be used as catalysts.

[0003] CN105646433A discloses a method for continuously preparing high-purity caprolactone. Organic acid and hydrogen peroxide are introduced into a reaction rectification tower, an oxidation reaction occurs under the catalysis of a strong acidic cation exchange resin, and water is separated out. The organic peroxy acid generated by the reaction enters the reaction rectification tower, and an oxidation reaction occurs with cyclohexanone to prepare a caprolactone crude liquid, which is then separated by rectification to obtain high-purity caprolactone. The use of an acidic resin as a catalyst can obtain a relatively high peroxy acid yield in the initial stage of the reaction, but as the long-term operation continues, the active component sulfonic acid group on the surface of the resin 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. The method uses 4-5 reaction rectification towers in series. The feed of hydrogen peroxide, boric acid catalyst, light components and phosphate ester is pre-mixed and then pumped into the rectification tower body in sequence. The liquid in the kettle of the last reaction rectification tower is introduced into a distillation rectification tower, and anhydrous peroxypropionic acid without catalyst is collected at the top of the distillation rectification tower. The kettle contains catalyst and phosphate ester, which is returned to the initial reactor to complete the cycle. CN110183417A discloses a method for continuously producing caprolactone by catalytic reaction rectification. The method uses the enrichment section of a reaction rectification tower to purify hydrogen peroxide. The purified hydrogen peroxide reacts with the remaining water-carrying agent and acetic acid to generate peroxyacetic acid and water. The generated water is carried out by the water-carrying agent, and the generated peroxyacetic acid is exchanged by heat and then goes up to react with cyclohexanone to generate caprolactone and acetic acid. The above two processes use weak acid catalysts (boric acid) or do not use acidic catalysts to synthesize peroxy acid. Although the yield of caprolactone is high, the yield of synthesized peroxy acid is low and the reaction time is long. The generated peroxy acid is extremely 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 peroxy acid, although a relatively ideal peroxy acid yield can be obtained, but the subsequent production is easy to cause the polymerization of caprolactone, so that its selectivity is poor; in addition, concentrated sulfuric acid is seriously corrosive to equipment and is difficult to recycle, the post-processing process is complex, and environmental pollution is easy to cause. Boric acid as a catalyst is less by-product in the process of preparing caprolactone, but the generation rate of peroxy acid is slow, the energy consumption is high, and the production efficiency is reduced. SUMMARY

[0006] The purpose of the present application is to solve the problems of low stability of the catalyst, low yield and poor selectivity of the synthesized peroxy acid and the disadvantage of industrial production in the prior art when preparing peroxy acid by using a catalyst, so that a catalyst, a preparation method and a method for preparing peroxy acid by using the catalyst are proposed. The present application uses heteropoly acid as an active component and uses molecular sieve modified by alkyl and amino as a carrier, which can load the heteropoly acid more firmly on the carrier, thereby improving the conversion rate of organic acid and the yield and selectivity of peroxy acid when preparing peroxy acid by using the catalyst, and the catalyst can be recycled and used for industrial production.

[0007] The first aspect of the present application proposes a catalyst, which comprises modified molecular sieve and heteropoly acid loaded on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with alkyl and amino, the alkyl and the amino act on the hydroxyl group on the surface of the molecular sieve and are bonded to the surface of the molecular sieve, and the anion of the heteropoly acid acts on the amino and is anchored to the surface of the molecular sieve.

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

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

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

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

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

[0013] The second aspect of the present application proposes a preparation method of a catalyst, which comprises the following steps:

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

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

[0016] (3) loading heteropoly acid: calcining the heteropoly acid, and then mixing the calcined product, a 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 type molecular sieve, porous MEL type molecular sieve and porous MOR type 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 aminoxysilane is selected from one or more of 3-aminotrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and anilinomethyltriethoxysilane.

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

[0022] Preferably, in step (1), the use amount ratio of the molecular sieve, in step (2), the aminoxysilane and the second organic solvent is 1: 2-5 g / mL: 5-12 g / mL.

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

[0024] Preferably, the first organic solvent and the second organic solvent are each 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 is 25-60°C, and time is 0.5-5 h.

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

[0028] The third aspect of the present application provides a method for preparing peroxo acid, which comprises: reacting the catalyst described above with organic acid and hydrogen peroxide at 25-55℃.

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

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

[0031] In the catalyst of the present application, the heteropoly acid is loaded on the molecular sieve modified by alkyl and amino, which can combine the advantages of the heteropoly acid, such as high catalytic activity, good selectivity, mild catalytic conditions and environmental friendliness, with the characteristics of the molecular sieve, such as facilitating the diffusion of the reactants and peroxo acid molecules. Meanwhile, the modification by alkyl and amino can enhance the loading firmness of the heteropoly acid. Therefore, when the catalyst of the present application is used to prepare peroxo acid, the conversion efficiency of the organic acid can be improved, and the peroxo acid 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 DRAWINGS

[0032] Figure 1 The scanning electron microscope image of the catalyst of SBA-15 supported phosphotungstic acid modified by alkyl amino prepared in Example 1 of the present application;

[0033] Figure 2 The infrared spectrum of the catalyst of SBA-15 supported phosphotungstic acid modified by alkyl amino prepared in Example 1 of the present application;

[0034] Figure 3 The scanning electron microscope image of the catalyst of SBA-15 supported phosphotungstic acid modified by amino prepared in Comparative Example 1 of the present application;

[0035] Figure 4 The infrared spectrum of the catalyst of SBA-15 supported phosphotungstic acid modified by amino prepared in Comparative Example 1 of the present application. DETAILED DESCRIPTION

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

[0037] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not considered critical for the purposes of the application. The endpoints of the ranges and any values are provided as approximations only and are understood to encompass a range of values around the endpoints. Any numerical value, however, can be expressed as approximately that value, and as used herein is understood to be open-ended to encompass approximately that value as well as values outside of the approximately stated value.

[0038] Scholars at home and abroad have prepared peroxy acid from organic acid under the action of acidic ion exchange resin, molecular sieve, heteropoly acid and composite metal oxide. Heteropoly acid is a kind of excellent environmental friendly catalytic material, which is not easy to decompose under strong oxidation condition, has high catalytic activity, good selectivity, mild catalytic condition and other advantages, can replace concentrated sulfuric acid and nitric acid in a series of fine synthesis to meet the environmental protection requirements. Although heteropoly acid has many advantages, it is difficult to recover due to its solubility in polar solvents, therefore, developing porous hydrophobic solid acid catalyst based on heteropoly acid for synthesizing peroxy acid is the key to solve the above problems. Based on this, the inventors of the present application have completed the following inventions.

[0039] The present application provides a catalyst, which comprises a modified molecular sieve and a heteropoly acid supported on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with alkyl and amino groups, specifically, the alkyl and the amino groups act on the hydroxyl groups on the surface of the molecular sieve and are bonded to the surface of the molecular sieve, and the anion of the heteropoly acid acts on the amino groups and is anchored to the surface of the molecular sieve. In this context, "anchored" means that the interaction between the heteropoly acid and the molecular sieve is strong.

[0040] In the catalyst of the present application, 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 application, 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 application, 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 application, in a specific embodiment, the porous molecular sieve has a SiO2 / Al2O3 molar ratio of 100-500, a specific surface area of 50-600 m 2 / g, and the pore volume is 0.1-1.5 mL / g, and 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 a porous MFI-type molecular sieve, a porous MEL-type molecular sieve, and a porous MOR-type molecular sieve.

[0044] In the catalyst according to the present application, in a specific embodiment, the content of the heteropoly acid is 10-80 wt%, for example, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, or 80 wt%, and the content of the modified molecular sieve is 20-90 wt%, for example, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, or 90 wt%, based on the total weight of the catalyst being 100 wt%.

[0045] According to a first specific embodiment of the catalyst according to the present application, the catalyst comprises a modified molecular sieve and a heteropoly acid supported on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with alkyl groups and amino groups, the alkyl groups and the amino groups respectively interact with the hydroxyl groups on the surface of the molecular sieve, and are bonded to the surface of the molecular sieve, and wherein the anion of the heteropoly acid interacts with the amino groups, and is anchored to the surface of the molecular sieve.

[0046] According to a second specific embodiment of the catalyst according to the present application, the catalyst comprises a modified molecular sieve and a heteropoly acid supported on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with alkyl groups and amino groups, the alkyl groups and the amino groups respectively interact with the hydroxyl groups on the surface of the molecular sieve, and are bonded to the surface of the molecular sieve, and wherein the anion of the heteropoly acid interacts with the amino groups, and is anchored to the surface of the molecular sieve; the content of the heteropoly acid is 10-80 wt%, and the content of the modified molecular sieve is 20-90 wt%, based on the total weight of the catalyst being 100 wt%.

[0047] According to a third specific embodiment of the catalyst according to the present application, the catalyst comprises a modified molecular sieve and a heteropoly acid supported on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with alkyl groups and amino groups, the alkyl groups and the amino groups respectively interact with the hydroxyl groups on the surface of the molecular sieve, and are bonded to the surface of the molecular sieve, and wherein the anion of the heteropoly acid interacts with the amino groups, and is anchored to the surface of the molecular sieve; the content of the heteropoly acid is 10-80 wt%, and the content of the modified molecular sieve is 20-90 wt%, based on the total weight of the catalyst being 100 wt%; and the heteropoly acid 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 application, the catalyst comprises a modified molecular sieve and a heteropoly acid supported on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with alkyl groups and amino groups, the alkyl groups and the amino groups respectively react with the hydroxyl groups on the surface of the molecular sieve and are bonded to the surface of the molecular sieve, and the anions of the heteropoly acid react with the amino groups and are anchored to the surface of the molecular sieve; the content of the heteropoly acid is 10-80% by weight and the content of the modified molecular sieve is 20-90% by weight based on the total weight of the catalyst; the heteropoly acid is selected from one or more than two of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid; and the molecular sieve in the modified molecular sieve is a mesoporous molecular sieve and / or a porous molecular sieve.

[0049] According to a fourth specific embodiment of the catalyst of the present application, the catalyst comprises a modified molecular sieve and a heteropoly acid supported on the modified molecular sieve, wherein the surface of the modified molecular sieve is modified with alkyl groups and amino groups, the alkyl groups and the amino groups respectively react with the hydroxyl groups on the surface of the molecular sieve and are bonded to the surface of the molecular sieve, and the anions of the heteropoly acid react with the amino groups and are anchored to the surface of the molecular sieve; the content of the heteropoly acid is 10-80% by weight and the content of the modified molecular sieve is 20-90% by weight based on the total weight of the catalyst; the heteropoly acid is selected from one or more than two of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid; and 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 than two 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 than two of porous MFI type molecular sieve, porous MEL type molecular sieve and porous MOR type molecular sieve.

[0050] The present application provides a preparation method of a catalyst, which comprises 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), an aminoxysilane and a second organic solvent;

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

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

[0055] In the method of the present application, 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 application, in a specific embodiment, the porous molecular sieve has a SiO2 / Al2O3 molar ratio of 100-500, a specific surface area of 50-600 m 2 / g, and a pore volume of 0.1-1.5 mL / g, and in particular, 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 type molecular sieve, porous MEL type molecular sieve and porous MOR type molecular sieve.

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

[0058] In the method of the present application, 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 application, in a specific embodiment, in step (1), the amounts of the molecular sieve, the alkoxysilane and the first organic solvent are 1 g: 2-5 mL: 5-12 mL, for example, 1 g: 2 mL: 5 mL, 1 g: 3.33 mL: 8.33 mL, 1 g: 4 mL: 10 mL or 1 g: 5 mL: 12 mL.

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

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

[0062] In the method of the present application, in a specific embodiment, in step (1), the filtering is carried out under a protective atmosphere. In a preferred embodiment, the protective atmosphere is argon, nitrogen or helium.

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

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

[0065] In the method of the present application, in a specific embodiment, in step (2), the aminoxysilane is selected from one or more of 3-aminotriethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and anilinomethyltriethoxysilane.

[0066] In the method of the present application, 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 application, in a specific embodiment, the ratio of the use amount of the molecular sieve in step (1), the aminoxysilane in step (2) and the second organic solvent is 2-5 mL:5-12 mL, for example, it can be 1 g:2 mL:5 mL, 1 g:3.33 mL:8.33 mL, 1 g:4 mL:10 mL or 1 g:5 mL:12 mL.

[0068] In the method of the present application, in a specific embodiment, in step (2), the reaction is performed under stirring. In a preferred embodiment, in step (2), the reaction is performed under the conditions of temperature of 25-60 °C, for example, 25 °C, 35 °C, 45 °C or 60 °C, and time of 0.5-5 h, for example, 0.5 h, 1 h, 2 h, 3 h, 4 h or 5 h.

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

[0070] In the method of the present application, in a specific embodiment, in step (2), the filtering 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 application, in a specific embodiment, in step (2), the washing is performed using an organic solvent; in a preferred embodiment, the organic solvent is toluene and / or methanol.

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

[0073] In the method of the present application, 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 application, in order to load the heteropoly acid better, the heteropoly acid needs to be activated first, and the method of activation is calcination, and in the specific embodiment, the calcination conditions in step (3) include: temperature of 300-400℃, time of 0.5-5h.

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

[0076] In the method of the present application, the heteropoly acid is loaded on the surface of the carrier by the excess impregnation method, and in the specific operation, the calcination product is dispersed in the third organic solvent, and the reaction product obtained in step (2) is added for mixing to be completely immersed.

[0077] In the method of the present application, in the specific embodiment, the ratio of the molecular sieve in step (1) to the amount of 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 application, in the specific embodiment, in step (3), the mixing is carried out under stirring. In the preferred embodiment, in step (3), the mixing conditions include: temperature of 10-35℃, stirring speed of 100-500rpm, time of 3-10h.

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

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

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

[0082] The third aspect of the present application provides a method for preparing peroxo acid, which comprises: reacting the catalyst described above with organic acid and hydrogen peroxide at 25-55℃.

[0083] In the method of the present application, in the specific operation, the catalyst described above is mixed and diluted with quartz sand first, and then placed in the reaction device, then the organic acid is pumped into the reaction device, and after the temperature reaches 25-55℃, the hydrogen peroxide is pumped into the reaction device.

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

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

[0086] In the method of the present application, in specific embodiments, the concentration of the hydrogen peroxide is 30-70 wt%, and the flow rate is 0.5-10 mL / min.

[0087] A catalyst according to the present application is further illustrated by the following examples. The examples are implemented on the premise of the technical solutions of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples.

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

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

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

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

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

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

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

[0095] Trimethoxysilane: manufacturer is Wokei Reagent, brand is XW010045.

[0096] N-octyltriethoxysilane: manufacturer is TCI Chemical Reagent, brand is TO0171100ML.

[0097] Test example

[0098] Mass concentration of peroxy acid: the analysis method of peroxy acid, refer to national standard "peroxyacetic acid solution GB / T19104-2021",

[0099]

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

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

[0102] RCOOH+H2O2→RCOOOH+H2O

[0103] Conversion rate of organic acid:

[0104]

[0105] n is the molar mass of the substance; the equilibrium conversion rate is the corresponding organic acid conversion rate when the reaction reaches reaction equilibrium.

[0106] Selectivity of peroxy acid:

[0107]

[0108] Yield of peroxy acid:

[0109] Y(RCOOOH) = X(RCOOH) x S(RCOOOH).

[0110] Example 1

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

[0112] (1) Alkyl modification: Weigh 12 g of SBA-15 molecular sieve into a single-necked flask, add 100 mL of toluene, then drop 40 mL of trimethoxysilane into the mixture under magnetic stirring, condense the resulting mixture under reflux at 45 °C for 4 h, then filter the condensed product under argon, wash the solid-phase product obtained by filtration with toluene and methanol, and finally dry under vacuum;

[0113] (2) Amino modification: Weigh the dry product obtained in step (1) into a single-necked flask, add 100 mL of toluene, then drop 45 mL of 3-aminotrimethoxysilane into the mixture under magnetic stirring, condense the resulting mixture under reflux at 45 °C for 4 h, then filter the condensed product under argon, wash the solid-phase product obtained by filtration with toluene and methanol, and finally dry under vacuum;

[0114] (3) Loading of heteropoly acid: Weigh 5 g of phosphotungstic acid and activate it by calcination at 350 °C for 3 h, disperse the calcined product in 100 mL of ethanol solvent to perform a first mixing, then perform a second mixing of the product obtained after the first mixing with the dry product obtained in step (2) at 25 °C and 200 rpm for 6 h, centrifuge the product obtained after the second mixing, wash it with water 3 times, and finally dry it at 110 °C for 10 h.

[0115] The method for preparing a peroxy acid comprises:

[0116] Weigh 3 g of the catalyst prepared in Example 1, mix and dilute it with 3 g of quartz sand, and load it into a fixed-bed reactor, then pump propionic acid into the fixed-bed reactor at a flow rate of 1.5 mL / min, after the temperature reaches 55 °C, finally pump hydrogen peroxide (concentration of 50 wt%) into the fixed-bed reactor at a flow rate of 0.8 mL / min to perform a reaction, connect a sample analyzer at the outlet of the reaction liquid, and analyze the concentration of peroxy propionic acid every 30 min. After 3 h, the equilibrium conversion rate of organic acid reaches 68.5%, the concentration of the prepared peroxy acid is 15.3%, the yield is 67.1%, and the selectivity is 98.5%.

[0117] Example 2

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

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

[0120] Example 3

[0121] The method for preparing the catalyst was carried out in the same manner as in Example 1, except that the SBA-15 molecular sieve was replaced with the MCM-41 molecular sieve.

[0122] The method for preparing the peroxy acid was carried out in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced with the catalyst prepared in Example 3. After 3 h, the equilibrium conversion of the organic acid was 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 was carried out in the same manner as in Example 1, except that the SBA-15 molecular sieve was replaced with the KIT-6 molecular sieve.

[0125] The method for preparing the peroxy acid was carried out in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced with the catalyst prepared in Example 4. After 3 h, the conversion of the organic acid was 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 was carried out in the same manner as in Example 1, except that the SBA-15 molecular sieve was replaced with the porous MEL-type molecular sieve.

[0128] The method for preparing the peroxy acid was carried out in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced with the catalyst prepared in Example 5. After 3 h, the equilibrium conversion of the organic acid was 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 was carried out in the same manner as in Example 1, except that the SBA-15 molecular sieve was replaced with the porous MOR-type molecular sieve.

[0131] The method for preparing the peroxy acid was carried out in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced with the catalyst prepared in Example 6. After 3 h, the conversion of the organic acid was 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 was carried out in the same manner as in Example 1, except that phosphotungstic acid was replaced by phosphomolybdic acid.

[0134] The method for preparing the peroxo acid was carried out 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 h, the equilibrium conversion of the organic acid was 68.7%, the concentration of the prepared peroxo 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 was carried out in the same manner as in Example 1, except that phosphotungstic acid was replaced by silicotungstic acid.

[0137] The method for preparing the peroxo acid was carried out 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 h, the equilibrium conversion of the organic acid was 65.2%, the concentration of the prepared peroxo 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 was carried out in the same manner as in Example 1, except that trimethoxysilane was replaced by n-octyltriethoxysilane in step (1).

[0140] The method for preparing the peroxo acid was carried out 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 h, the conversion of the organic acid was 69.3%, the concentration of the prepared peroxo 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 was carried out in the same manner as in Example 1, except that 3-aminotrimethoxysilane was replaced by 3-aminopropyltriethoxysilane in step (2).

[0143] The method for preparing the peroxo acid was carried out 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 h, the equilibrium conversion of the organic acid was 66.2%, the concentration of the prepared peroxo acid was 14.8%, the yield was 65.1%, and the selectivity was 98.3%.

[0144] Example 11

[0145] The method for preparing the catalyst was carried out in the same manner as in Example 1, except that in step (1), 12 g of SBA-15 molecular sieve was weighed into a single-necked flask, 100 mL of toluene was added, and then 60 mL of trimethoxysilane was added dropwise under magnetic stirring to mix.

[0146] The method for preparing the peroxo acid was carried out in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced with the catalyst prepared in Example 11. After 3 h, the equilibrium conversion of the organic acid reached 68.8%, the concentration of the prepared peroxo 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 was carried out in the same manner as in Example 1, except that in step (1), 12 g of SBA-15 molecular sieve was weighed into a single-necked flask, 100 mL of toluene was added, and then 24 mL of trimethoxysilane was added dropwise under magnetic stirring to mix.

[0149] The method for preparing the peroxo acid was carried out in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced with the catalyst prepared in Example 12. After 3 h, the equilibrium conversion of the organic acid reached 65.2%, the concentration of the prepared peroxo 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 was carried out in the same manner as in Example 1, except that in step (2), the dried product obtained in step (1) was placed in a single-necked flask, 100 mL of toluene was added, and then 60 mL of 3-aminotrimethoxysilane was added dropwise under magnetic stirring to mix.

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

[0153] Example 14

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

[0155] (1) Alkyl modification: 12 g of SBA-15 molecular sieve was weighed into a single-necked flask, 100 mL of acetonitrile was added, then 40 mL of trimethoxysilane was added dropwise under magnetic stirring to mix, the resulting mixture was stirred under reflux condensation at 25°C for 1 h, then the condensed product was filtered under argon, 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, then 45 mL of 3- aminotrimethoxysilane was added dropwise under magnetic stirring to mix, the resulting mixture was stirred under reflux condensation at 60°C for 5 h, then the condensed product was filtered under argon, the solid-phase product obtained by filtration was washed with toluene and methanol, and finally vacuum dried;

[0157] (3) Loading of heteropoly acid: 5 g of phosphotungstic acid was weighed and activated by calcination at 300°C for 3 h, the calcined product was dispersed in 100 mL of ethanol solvent for first mixing, then the first mixed product was mixed with 5 g of the dried product obtained in step (2) for second mixing at 25°C and 200 rpm, the time used was 6 h, the second mixed product was centrifuged, washed with water 3 times, and finally dried at 120°C for 6 h.

[0158] The method for preparing peroxo acid comprises:

[0159] 3 g of the catalyst prepared in Example 14 was weighed, mixed and diluted with 3 g of quartz sand, and then packed into a fixed bed reactor, 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% by weight) was pumped into the fixed bed reactor at a flow rate of 0.8 mL / min for reaction, sample analysis was performed at the outlet of the reaction liquid, and the concentration of peroxo propionic acid was analyzed every 30 min. After 3 h, the equilibrium conversion rate of organic acid reached 67.7%, the concentration of the prepared peroxo 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 was carried out in the manner of Example 1, except that step (1) of alkyl modification was not performed, and the SBA-15 molecular sieve was directly subjected to amino modification in step (2) and loading of heteropoly acid in step (3).

[0162] The method for preparing peroxyacid was carried out in accordance with Example 1, except that the catalyst prepared in Example 1 was replaced with 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 peroxyacid 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 was carried out in accordance with the method of Example 1, except that the amino modification in step (2) was not performed, and the alkyl-modified product was directly loaded with heteropolyacid.

[0165] The method for preparing peroxyacid was carried out in accordance with Example 1, except that the catalyst prepared in Example 1 was replaced with 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 peroxyacid 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 was carried out in accordance with Example 1, except that the heteropoly acid in step (3) was replaced with boric acid.

[0168] The method for preparing peroxyacid was carried out in accordance with Example 1, except that the catalyst prepared in Example 1 was replaced with the catalyst prepared in Comparative Example 3. After 3 hours, the conversion rate of organic acid reached 5.7%, the concentration of the prepared peroxyacid was 2.1%, the yield was 4.6%, and the selectivity was 81.1%.

[0169] Comparative Example 4

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

[0171] The method for preparing peroxyacid was carried out in accordance with Example 1, except that the catalyst prepared in Example 1 was replaced with 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 peroxyacid 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 was carried out in accordance with Example 1, except that the molecular sieve was first modified with amino groups, then the amino-modified molecular sieve was modified with alkyl groups, and finally the amino- and alkyl-modified molecular sieves were loaded with heteropoly acids.

[0174] The method for preparing peroxy acid was carried out in the same manner as in Example 1, except that the catalyst prepared in Example 1 was replaced with the catalyst prepared in Comparative Example 5. After 3 h, the equilibrium conversion of the organic acid was 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 according to the present application is used to prepare peroxy acid, the equilibrium conversion of the organic acid can be improved, the equilibrium conversion is >60%, the selectivity is >98%, and the catalyst can be recycled and reused, and is suitable for industrial production.

[0176] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application, and all fall within the protection scope of the present application.

Claims

1. A method for preparing peroxyacid, characterized in that, The method includes: (1) Alkyl modification: The molecular sieve, alkoxysilane and the first organic solvent are reacted; (2) Amino modification: The reaction product obtained in step (1), aminooxysilane, and a second organic solvent are reacted; (3) Loading heteropolyacids: The heteropolyacids are calcined, and then the calcined product, the third organic solvent, and the reaction product obtained in step (2) are mixed; (4) The catalyst prepared in step (3) is reacted with organic acid and hydrogen peroxide at 25-55℃; In step (3), the heteropoly acid is selected from one or more of phosphotungstic acid, phosphomolybdic acid and silicotungstic acid; In step (3), the ratio of the molecular sieve in step (1) to the heteropoly acid in step (3) is 0.25-9:1; In step (4), 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; In step (4), the organic acid is selected from one or more of formic acid, acetic acid, propionic acid, benzoic acid and m-chlorobenzoic acid.

2. The method according to claim 1, characterized in that, The molecular sieve is a mesoporous molecular sieve and / or a porous molecular sieve.

3. The method according to claim 2, 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.

4. The method according to claim 3, characterized in that, The porous molecular sieve is selected from one or more of the following: porous MFI type molecular sieve, porous MEL type molecular sieve, and porous MOR type molecular sieve.

5. The method according to claim 1, characterized in that, The alkoxysilane is trimethoxysilane and / or n-octyltriethoxysilane.

6. The method according to claim 5, characterized in that, The aminooxysilane is selected from one or more of 3-aminotrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and anilinemethyltriethoxysilane.

7. The method according to claim 1, characterized in that, In step (1), the ratio of the molecular sieve, the alkoxysilane and the first organic solvent is 1g:2-5mL:5-12mL.

8. The method according to claim 1, characterized in that, The ratio of the molecular sieve in step (1), the aminooxysilane in step (2), and the second organic solvent is 1g:2-5mL:5-12mL.

9. The method according to claim 1, 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.

10. The method according to claim 1, characterized in that, The third organic solvent is selected from one or more of ethanol, methanol, acetone and n-hexane.

11. The method according to claim 1, characterized in that, In step (1), the reaction conditions include a temperature of 25-60°C and a time of 0.5-5h.

12. The method according to claim 1, characterized in that, In step (2), the reaction conditions include a temperature of 25-60°C and a time of 0.5-5h.

13. The method according to claim 1, characterized in that, In step (4), the concentration of the hydrogen peroxide is 30-70% by weight.

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