Preparation method and application of a polymer-supported NHPI and sulfonic acid bifunctional catalyst

Abstract

The present invention discloses a method for preparing a polymer-supported NHPI and sulfonic acid bifunctional catalyst and its application. The present invention copolymerizes an olefin monomer bearing a sodium sulfonate salt group with a crosslinking functional group monomer under solvent thermal conditions. Then, a polymer carrying sulfonic acid groups is obtained through ion exchange in an acid medium. The NHPI-supported sulfonic acid polymer is further obtained through the reaction of anhydride and hydroxylamine salt. The bifunctional polymer of the present invention catalyzes the oxidative decomposition reaction of cyclohexylbenzene, producing phenol and co-producing cyclohexanone in a single step. The catalyst prepared by the present invention is easily recyclable and has good reusability.

Description

Technical Field

[0001] The present invention relates to the preparation of catalytic materials, and in particular to a preparation method and application of a polymer-supported NHPI and sulfonic acid bifunctional catalyst. Background Art

[0002] Phenol and cyclohexanone are important organic chemical raw materials in the chemical industry, primarily used in the production of various chemical products and intermediates, including phenolic resins, bisphenol A, caprolactam, and adipic acid. They are also widely used in the pharmaceutical, pesticide, fragrance, dye, and oil refining industries. In recent years, with the rapid development of industries such as electronics and communications, the automotive industry, and construction, the demand for bisphenol A and phenolic resins has increased significantly, driving strong growth in demand for phenol.

[0003] The cumene oxidation process is currently the predominant industrial method for producing phenol, accounting for approximately 92% of the world's total phenol production capacity. The cumene process primarily involves three steps: cumene is first oxidized to form cumene hydroperoxide (CHP), which is then acidolyzed over an acid catalyst to produce phenol and acetone. The cumene oxidation process uses air as the oxidant, resulting in a long induction period, slow reaction rate, high operating temperature, and numerous byproducts. Because the intermediate CHP in the oxidation reaction can act as an initiator, the reaction also has drawbacks such as high risk of runaway reaction and even explosion. Furthermore, for every ton of phenol produced, the cumene oxidation process also produces approximately 0.62 tons of acetone. However, global demand for phenol is growing faster than that for acetone, making acetone a relatively low-value co-product. Furthermore, cumene is obtained through the alkylation of propylene, a raw material cost that is also increasing. Therefore, finding an alternative to the cumene oxidation process that avoids propylene as a feedstock and simultaneously produces higher-value-added ketones is an attractive alternative route for producing phenol. Cyclohexylbenzene (CHB) has a similar chemical structure to cumene; both contain a tertiary carbon atom attached to a benzene ring. Cyclohexylbenzene can be produced from a single feedstock, benzene, through hydroalkylation. The reaction pathway for producing cyclohexylbenzene via benzene hydroalkylation is shown in Formula (I).

[0004]

[0005] Cyclohexylbenzene can also be oxidized by oxygen in the air to produce cyclohexylbenzene peroxide (CHBHP), which can then be decomposed with acid to produce phenol and cyclohexanone, another very important chemical raw material. The cyclohexylbenzene process for producing phenol and co-producing cyclohexanone uses only inexpensive and widely available benzene as a raw material. Furthermore, the co-product cyclohexanone can also be dehydrogenated to phenol. This method can effectively address the limited production capacity of phenol produced using the cumene process in my country. The reaction pathway for producing phenol and co-producing cyclohexanone by catalytic oxidation and acid cleavage of CHB is shown in Formula (II).

[0006]

[0007] The cyclohexylbenzene oxidation reaction is a typical free radical chain reaction that can proceed spontaneously in the absence of a catalyst. However, the uncatalyzed reaction takes a long time and has low conversion and selectivity. All ten secondary hydrogens of cyclohexylbenzene may be oxidized to form by-products. The oxidation intermediate CHBHP is also prone to beta-cracking side reactions. The selectivity of cyclohexylbenzene oxidation decreases rapidly with increasing conversion. The N-hydroxyphthalimide (NHPI) catalytic system exhibits high catalytic activity and selectivity in the oxidation reaction of hydrocarbons. Although NHPI is an effective oxidation catalyst, it has disadvantages such as difficulty in separating the catalyst from the product and difficulty in recycling. When NHPI is fixed in a polymer through an amide or ester bond, its structure is more stable than that of the NHPI catalyst, and it is easy to separate and recycle, with a good catalytic effect. Some scholars (Catal Lett (2016) 146: 1991–2000) copolymerized ethyl propylene glycol and divinylbenzene under solvent thermal conditions to prepare a polymer-supported NHPI catalyst with a loading of 2.06 mmol / g and a high catalytic yield.

[0008] The decomposition of CHBHP is an acid-catalyzed reaction. B acids such as sulfuric acid, phosphoric acid, hydrochloric acid, and p-toluenesulfonic acid, as well as L acids such as FeCl₃, ZnCl₂, and BF₃, can effectively catalyze the reaction. Sulfuric acid is used in the industrial decomposition of CHP. However, sulfuric acid catalysts are highly corrosive, prone to inducing certain side reactions, difficult to separate impurities from products, and require subsequent alkaline neutralization, resulting in wastewater treatment. The use of solid acids is an effective solution to these problems. Phillips Petroleum, in its patent US4487970, proposed using an SbF₅ / graphite catalyst to catalyze the decomposition of CHBHP, achieving yields of 99% for both phenol and cyclohexanone. Exxon-Mobil, in its patents US0296577 A1 and US103880601 A, proposed using a composite composed of a FAU-type silicate molecular sieve, an oxide binder, and clay as a catalyst for the decomposition of CHBHP. It has been reported in the literature (Applied Catalysis A: General 510 (2016) 125–133) that sodium p-styrenesulfonate and divinylbenzene were copolymerized under solvent thermal conditions, and then a polymer-supported sulfonic acid catalyst was synthesized by proton exchange. The sulfur content of the catalyst was 2.5 mmol / g, and the acid catalytic effect was good.

[0009] Vol. 41, No. 9 of Petrochemicals reported on the catalytic oxidation of CHB to phenol and cyclohexanone using NHPI. Using acetonitrile as the solvent, an oxygen pressure of 1.1 MPa, and a reaction temperature of 75°C for 3 hours, the CHB conversion was 40.2%. After sulfuric acid-catalyzed cracking, the selectivities for cyclohexanone and phenol were 95.6% and 98.4%, respectively. Acta Petrolei Sinica, Vol. 33, No. 5, reported on the use of NC-700 as the catalyst, with an oxygen partial pressure of 0.9 MPa and a reaction temperature of 130°C for 4 hours. The catalyst was separated from the prepared oxidation solution, which was then acid-hydrolyzed with 2.0 g of D001 sulfonic acid resin at 50°C for 4 hours. The result was a CHB conversion of 18.3%, with selectivities for cyclohexanone and phenol of 81.8% and 71.7%, respectively. Modern Chemical Industry, Vol. 35, No. 9, reported the oxidation of cyclohexylbenzene catalyzed by g-C3N4 / BC. The reaction was conducted at 110°C for 4 hours under 1.1 MPa of O2. The oxidized solution, obtained by solid-liquid separation, was then acidified with 5% sulfonic acid resin for 2 hours, resulting in a CHB conversion of 16.7% and selectivities of 64.0% and 57.0% for phenol and cyclohexanone, respectively. Acta Petrolei Sinica, Vol. 36, No. 2, reported the oxidation of cyclohexylbenzene catalyzed by CPS-NHPI-C6 at 95°C under 1.0 MPa of O2 for 8 hours. The resulting oxidized solution was then acidified with 2.0 g of D001 sulfonic acid resin at 50°C for 4 hours, achieving a CHB conversion of 28.4% and selectivities of 90.7% and 87.64% for cyclohexanone and phenol, respectively.

[0010] The cumene process typically involves the uncatalyzed oxidation of cumene to produce peroxide. The oxidized liquid is then concentrated and subjected to a sulfuric acid-catalyzed decomposition reaction. Existing cyclohexylbenzene process research typically involves the catalytic oxidation of cyclohexylbenzene to produce CHBHP. The resulting oxidized liquid undergoes solid-liquid separation to remove the oxidation catalyst, followed by concentration or direct acid-catalyzed cleavage of the oxidized liquid to produce phenol and cyclohexanone.

[0011] The catalytic oxidation and acid-catalyzed decomposition of cyclohexylbenzene require their own reaction media and process conditions, resulting in some differences in their optimal conditions. The NHPI-catalyzed cyclohexylbenzene oxidation reaction is typically conducted in acetonitrile at a temperature of 70-120°C for 3-7 hours. The sulfuric acid-catalyzed decomposition reaction is typically conducted at a temperature of 30-80°C for 1-4 hours, with the addition of a solvent such as acetone for heat removal. The oxidation reaction requires high temperatures, and the resulting CHBHP readily undergoes thermal decomposition to form phenylcyclohexanol and β-cleavage to form hexanophenone. This makes it difficult to achieve high selectivity, with CHBHP selectivity generally exceeding 90%. Furthermore, the NHPI oxidation catalyst is expensive and difficult to recycle, and residual NHPI in the oxidation solution can affect subsequent decomposition reactions. Using solid acids instead of sulfuric acid for the decomposition reaction can avoid the equipment and post-processing environmental issues associated with sulfuric acid systems, but solid acids struggle to achieve comparable catalytic performance. Summary of the Invention

[0012] Aiming at the technical problems that the cyclohexylbenzene process is carried out in two steps, namely oxidation and decomposition, which has complicated process steps, many oxidation side reactions, and difficulty in separating and recovering the catalyst, the present invention provides a method for preparing a polymer-supported NHPI and sulfonic acid bifunctional catalyst, and applies the catalyst to catalyze the one-step oxidation-decomposition reaction of cyclohexylbenzene.

[0013] The present invention provides a method for preparing a polymer-supported NHPI and sulfonic acid bifunctional catalyst, comprising the following steps:

[0014] (1) Using an organic compound as a crosslinking functional group monomer, a sulfonic acid group-containing compound and an initiator are added to a tetrahydrofuran aqueous solution and stirred until completely dissolved;

[0015] (2) subjecting the solution obtained in step (1) to a copolymerization reaction under solvent thermal conditions, obtaining a reaction product a after the reaction is completed, and soaking the product a in water and / or ethanol to obtain a soaked product b;

[0016] (3) evaporating the soaked material b obtained in step (2) (e.g., rotary evaporation), filtering and washing (e.g., suction filtration), and drying to obtain a high molecular weight polymer solid c;

[0017] (4) converting the solid c obtained in step (3) into a proton form by ion exchange in an acid solution to obtain a reaction solution d;

[0018] (5) subjecting the reaction solution d obtained in step (4) to solid-liquid separation (by centrifugation, suction filtration, rotary evaporation, etc.) to obtain a solid e;

[0019] (6) filtering, washing, and drying the solid e obtained in step (5) to obtain a high molecular weight polymer solid f;

[0020] (7) adding the solid f obtained in step (6) to a dichloromethane-pyridine solution, stirring, and cooling in an ice-water bath, and then adding a chlorotrimellitate anhydride solution thereto, stirring in an ice-water bath and at room temperature, respectively, to obtain a reaction solution g;

[0021] (8) filtering, washing, and drying the reaction solution g obtained in step (7) to obtain an immobilized acid anhydride polymer solid h;

[0022] (9) adding the solid h obtained in step (8) to a dichloroethane-pyridine solution, adding hydroxylamine hydrochloride, and refluxing with stirring to obtain a reaction solution i;

[0023] (10) The reaction solution i obtained in step (9) is filtered, washed, and dried to obtain a polymer-supported NHPI and sulfonic acid bifunctional catalyst f.

[0024] Furthermore, in step (1), the molar ratio of the total amount of the compound containing sulfonic acid groups to the initiator is 1:(0.001-0.1); the initiator is benzoyl peroxide or azobisisobutyronitrile.

[0025] Furthermore, in step (1), the sulfonic acid group-containing compound is one or more of sodium p-styrene sulfonate, sodium vinyl sulfonate, and styrene disulfonic acid; the cross-linking functional group monomer is one or more of 2-hydroxyacrylate, divinylbenzene, and acrylamide; and the molar ratio of the total amount of the sulfonic acid group-containing compound to the cross-linking functional group monomer is (0.05-5.00):1, preferably (0.1-2.5):1, and more preferably (0.5-2.0):1.

[0026] Furthermore, in step (2), the solvent thermal condition has a temperature of 50 to 150° C. and a time of 12 to 48 hours.

[0027] Furthermore, in step (3), the washing is performed 1 to 3 times using one or more of the solvents dichloromethane, N,N-dimethylformamide, dichloroethane, tetrahydrofuran, and ether, the washing temperature is 50 to 90° C., and the washing time is 0.5 to 2 h; the drying is performed by vacuum drying at a temperature of 50 to 150° C. and a time of 12 to 48 h.

[0028] Furthermore, in step (4), the acid solution is a sulfuric acid solution and / or a hydrochloric acid solution, the concentration of the acid solution is 0.1 to 2 mol / L, the reaction temperature is 25 to 80° C., and the reaction time is 12 to 48 h.

[0029] Furthermore, in step (5), evaporation is preferably rotary evaporation, and washing or rotary evaporation is performed 5 to 10 times using one or more of solvents selected from water, ethanol, dichloroethane, ether, and ethanol aqueous solution, the washing or rotary evaporation temperature is 20 to 90° C., and the washing or rotary evaporation time is 2 to 5 hours.

[0030] Furthermore, in step (6), the washing is performed 1 to 3 times using one or more of the solvents dichloromethane, N,N-dimethylformamide, dichloroethane, tetrahydrofuran, and ether, the washing temperature is 50 to 90° C., and the washing time is 0.5 to 2 h; the drying is performed by vacuum drying at a temperature of 50 to 150° C. and a time of 12 to 48 h.

[0031] Furthermore, in step (7), the cooling time in the ice-water bath is 1 to 3 hours; the chlorotrimellitic anhydride solution is obtained by dissolving chlorotrimellitic anhydride in dichloromethane, and the addition method is dropwise addition, and the molar ratio of chlorotrimellitic anhydride to the cross-linking functional group monomer is (0.1 to 1):1; the stirring time in the ice-water bath is 1 to 5 hours; and the stirring time at room temperature is 12 to 48 hours.

[0032] Furthermore, in step (8), the washing is performed by using one or more of the solvents ethanol, water, ethanol aqueous solution, dichloromethane, tetrahydrofuran, and ether for 1 to 3 times, the washing temperature is 50 to 90° C., and the washing time is 0.5 to 2 h; the drying is vacuum drying at a temperature of 50 to 150° C. and a time of 12 to 48 h.

[0033] Furthermore, in step (7) and step (9), the dichloroethane-pyridine solution is a solution composed of dichloroethane and pyridine in a volume ratio of 1 to 5:1.

[0034] Furthermore, in step (9), the molar ratio of hydroxylamine hydrochloride to trimellitic anhydride chloride is (0.1-1):1; the reaction temperature is 50-150° C., and the reaction time is 12-48 h.

[0035] Furthermore, in step (10), the washing is performed 1 to 3 times with one or more of the solvents ethanol, water, ethanol aqueous solution, dichloromethane, tetrahydrofuran, and ether, the washing temperature is 50 to 90° C., and the washing time is 0.5 to 2 h; the drying is performed by vacuum drying at a temperature of 50 to 150° C. and a time of 12 to 48 h.

[0036] The polymer-supported NHPI and sulfonic acid bifunctional catalyst prepared by the above method has characteristic peaks of N-OH and -SO3H and good thermal stability.

[0037] The application of the polymer-supported NHPI and sulfonic acid bifunctional catalyst obtained by the above preparation method in catalyzing the oxidation-decomposition one-step reaction of cyclohexylbenzene: using cyclohexylbenzene as the reaction raw material, under the catalytic conditions of the polymer-supported NHPI and sulfonic acid bifunctional catalyst prepared above, cyclohexylbenzene undergoes an oxidation-decomposition one-step reaction to prepare phenol and cyclohexanone.

[0038] Furthermore, the reaction is carried out in the presence of a solvent; the solvent is one or more of acetonitrile, benzonitrile, and acetic acid; and the mass ratio of the solvent to cyclohexylbenzene is 1 to 5:1.

[0039] Furthermore, the mass fraction of the polymer-supported NHPI and the sulfonic acid bifunctional catalyst in the reaction solution is 1.0% to 10.0%; the initial oxygen pressure is 0.50 to 2.50 MPa; the reaction temperature is 50 to 140° C., and the reaction time is 4 to 12 hours.

[0040] The beneficial effects of the present invention are:

[0041] (1) The polymer-supported NHPI and sulfonic acid bifunctional catalyst prepared in this invention achieves a one-step oxidation-decomposition reaction of cyclohexylbenzene under the same conditions. This one-step process eliminates the need for separation of the oxidation catalyst and concentration of the oxidation solution required in the step-by-step process, offering the potential advantages of a streamlined process and reduced energy consumption.

[0042] (2) The present invention uses a constructed high molecular polymer as a carrier to achieve base-position isolation of the N-OH and sulfonic acid groups in the catalyst. There is no interaction between the two active groups, but the intermediate product cyclohexylbenzene hydroperoxide generated by the oxidation reaction of cyclohexylbenzene at the N-OH position can be quickly contacted with the adjacent sulfonic acid acid site through the same carrier to carry out the next decomposition reaction. This process of in-situ peroxide consumption can largely avoid the occurrence of oxidation side reactions, thereby improving the selectivity of the oxidation reaction, and allowing the catalytic reaction to proceed in the direction of generating phenol and cyclohexanone, which is also conducive to improving the overall selectivity of the reaction.

[0043] (3) The polymer-supported NHPI and sulfonic acid bifunctional catalyst prepared by the present invention has good thermal stability, is easy to separate from the reaction solution and reuse, and simultaneously solves the problem of separation and recovery of the catalyst in the oxidation and decomposition step reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The infrared characterization spectra of a series of samples and recovered polymer-supported NHPI and sulfonic acid bifunctional catalysts show obvious characteristic peaks of N-OH and sulfonic acid groups in the spectra. After being used in the reaction and recovered, the characteristic peaks of the bifunctional catalyst of the present invention remain basically unchanged, indicating that its structure is stable.

[0045] Figures 2 to 5 This is the thermogravimetric analysis diagram of the polymer-supported NHPI and sulfonic acid bifunctional catalyst, where: Figure 2 This is the TG general map, Figure 3 For NHPI, Figure 4 For HEA / DVB-NHPI, Figure 5 It is HEA / HSS-NHPI. It can be seen from the figure that compared with the NHPI catalyst, the polymer-supported NHPI and sulfonic acid bifunctional catalyst has a more stable structure and better thermal stability. DETAILED DESCRIPTION

[0046] The present invention is further described below using specific examples. The following examples are only for illustration, and the present invention is not limited thereto.

[0047] Example 1

[0048] 6.9 g of 2-hydroxyacrylate and 6.7 g of sodium p-vinylbenzenesulfonate were mixed and then added to an aqueous solution containing 0.48 g of benzoyl peroxide and 40 mL of tetrahydrofuran. The mixture was stirred at room temperature until completely dissolved. The mixture was heated at 100°C for 24 h. The resulting product was washed with dichloromethane, N,N-dimethylformamide, dichloroethane, tetrahydrofuran, and diethyl ether in sequence at room temperature three times. The filtered solid was dried in a vacuum drying oven at 80°C for 12 h to obtain the H-PHEA-SO3Na sample. This sample was acidified with 1 mol / L hydrochloric acid and stirred for 24 h. The remaining solution was evaporated to dryness using a rotary evaporator. The copolymer was removed, washed with water, and filtered until the filtrate was neutral. The filtered solid was dried in a vacuum drying oven at 80°C for 12 h to obtain a light yellow solid HEA / HSS. A mixture of this solid and 30 mL of DCM and 10 mmol of pyridine was cooled to 0°C in an ice-water bath. Then, 10 mmol of a solution of trimellitic anhydride chloride was added. The reaction mixture was stirred at 0°C for 3 hours and then at room temperature for an additional 24 hours. The mixture was filtered and washed twice with 10 mL of water, 10 mL of ethanol, 10 mL of ethanol-water solution, and 10 mL of diethyl ether, in that order. The resulting product, HEA / HSS-TAC, was dried in a vacuum oven at 80°C for 12 hours. This product was dissolved in pyridine solution, and 10 mmol of hydroxylamine hydrochloride was added. The mixture was stirred at 75°C for 24 hours. The mixture was washed three times with ethanol, water, ethanol-water solution, dichloromethane, tetrahydrofuran, and diethyl ether, in that order. The resulting material was dried in a vacuum oven at 80°C for 12 hours. The resulting material was designated r1-HEA / HSS-NHPI.

[0049] Example 2

[0050] The operating process of Example 1 was followed, except that 10.90 g of sodium p-vinylbenzenesulfonate was used. The obtained material was designated as r2-HEA / HSS-NHPI.

[0051] The following examples illustrate the method for preparing phenol and cyclohexanone by a one-step liquid-phase oxidation-decomposition reaction of cyclohexylbenzene provided by the present invention.

[0052] The raw material used in the following examples and comparative examples is cyclohexylbenzene with a purity greater than 98%, the solvent used is acetonitrile with a purity greater than 99%, the oxidation catalyst used is NHPI with a purity greater than 98%, the acid catalyst used is Amberlyst-15 with a purity greater than 98%, and the oxygen source used is pure oxygen.

[0053] In the reaction solutions of the following examples and comparative examples, the content of cyclohexylbenzene hydroperoxide was analyzed by iodine titration, the content of cyclohexylbenzene was analyzed by HPLC external standard method, and the content of phenol and cyclohexanone was analyzed by gas chromatography internal standard method.

[0054] Example 3

[0055] The cyclohexylbenzene oxidation-decomposition reaction was carried out in a 100 mL passivated autoclave equipped with a polytetrafluoroethylene liner and a stirring paddle. 20.00 g of cyclohexylbenzene, 0.42 g of the catalyst prepared in Example 1, and 20.00 g of acetonitrile (the reaction solvent) were added to the autoclave all at once. 1.50 MPa of oxygen was introduced, and the reaction was stirred at 120°C for 6 hours. After the reaction was completed, the reaction mixture was rapidly cooled to room temperature, slowly vented, and the pressure was released. The autoclave was opened, and the reaction liquid was removed for analysis by liquid chromatography and gas chromatography. The conversion of cyclohexylbenzene was 12.03%, and the selectivities for phenol and cyclohexanone were 62.88% and 51.52%, respectively.

[0056] Example 4

[0057] The operation process of Example 3 was followed, except that 0.42 g of the catalyst prepared in Example 2 was added to carry out the reaction. The conversion of cyclohexylbenzene was 13.63%, and the selectivities of phenol and cyclohexanone were 83.58% and 79.62%, respectively.

[0058] Comparative Example 1

[0059] NHPI was used as an oxidation catalyst to catalyze the CHB oxidation reaction. 20.00g of cyclohexylbenzene, 0.42g of NHPI, and 20.00g of the reaction solvent, acetonitrile, were added to a reactor all at once. 1.50MPa of oxygen was introduced, and the reaction was stirred at 120°C for 6 hours. After the reaction, the reaction mixture was rapidly cooled to room temperature, and analyzed by liquid chromatography and gas chromatography. The cyclohexylbenzene conversion was 51.1%, and the CHBHP selectivity was 48.14%. No phenol or cyclohexanone was produced in the reaction mixture.

[0060] Comparative Example 2

[0061] HEA / HSS was used as an acid catalyst to catalyze the decomposition of CHBHP. 10.00 g of the oxidation solution obtained in Comparative Example 1 (CHBHP concentration: 14.25%) and 0.30 g of HEA / HSS were added to a reactor at once. The mixture was stirred at 120°C for 2 hours. After the reaction, the mixture was rapidly cooled to room temperature, and the reaction solution was removed and analyzed by gas chromatography. The CHBHP conversion was 95.03%, the selectivity for phenol was 54.11%, and the selectivity for cyclohexanone was 53.53%.

[0062] Comparative Example 3

[0063] NHPI and a HEA / HSS mixed catalyst were reacted. 20.00g of cyclohexylbenzene, 0.42g of NHPI, 0.42g of HEA / HSS, and 20.00g of the reaction solvent, acetonitrile, were added all at once to an autoclave. 1.50MPa of oxygen was introduced and stirred at 120°C for 6 hours. After the reaction, the mixture was rapidly cooled to room temperature and slowly vented to release the pressure. The reaction liquid was then collected and analyzed by liquid chromatography and gas chromatography. The cyclohexylbenzene conversion was 11.63%, and the selectivities for phenol and cyclohexanone were 15.7% and 29.84%, respectively.

[0064] The catalytic effect of solid acids in acid decomposition reactions is not ideal. However, the inventors discovered during experiments that by matching appropriate process conditions and then increasing the acid strength, the reaction effect can be significantly improved. This can be seen from the comparison of the results of Examples 3 and 4 above. In the sample obtained by increasing the amount of sodium vinylbenzenesulfonate used in the catalyst preparation process, the acid strength of the catalyst can be effectively increased, and the selectivity of CHBHP decomposition into phenol and cyclohexanone is significantly improved. This also shows that the decomposition reaction of CHBHP has high requirements for the acid strength of the catalyst.

[0065] In Comparative Example 1, NHPI was used to catalyze the CHB oxidation reaction, and the selectivity of the target product CHBHP was only 48.14%. In Comparative Example 2, HEA-co-HSS was used as an acid catalyst to decompose the oxidation liquid prepared in Comparative Example 1. The conversion of CHBHP was 95.03%, and the selectivities of phenol and cyclohexanone were 54.11% and 53.53%, respectively. This indicates that under the same reaction conditions, the selectivity of the oxidation reaction in the two-step method is not high, the CHBHP concentration in the prepared oxidation liquid is not high, and other by-products are present, which leads to low selectivity of phenol and cyclohexanone products obtained in the second-step decomposition reaction.

[0066] Therefore, using the bifunctional catalyst prepared by the present invention to carry out the oxidation-decomposition reaction in a one-step process is beneficial for improving oxidation selectivity and also improving the selectivity of the decomposition products phenol and cyclohexanone. Comparative Example 3, using the oxidation catalyst NHPI and the acid catalyst HEA / HSS after physical mixing to carry out the oxidation-decomposition reaction of cyclohexylbenzene, achieved a conversion rate similar to that of the polymer-supported NHPI and sulfonic acid bifunctional catalyst, but the selectivity of phenol and cyclohexanone was significantly lower, indicating that the physical mixing of the two catalysts may cause mutual interference between the active components, while the polymer-supported bifunctional catalyst can produce a synergistic catalytic effect.

[0067] From the overall results, the polymer-supported NHPI and sulfonic acid bifunctional catalyst prepared in the present invention can realize the one-step oxidation-decomposition of cyclohexylbenzene to prepare phenol and cyclohexanone, which can not only improve the reaction efficiency but also obtain better reaction results.

Claims

1. Application of a polymer-supported NHPI and sulfonic acid bifunctional catalyst in catalyzing the oxidation-decomposition one-step reaction of cyclohexylbenzene, characterized in that: Cyclohexylbenzene is used as a reaction raw material. Under the catalytic conditions of a polymer-supported NHPI and a sulfonic acid bifunctional catalyst, cyclohexylbenzene undergoes an oxidation-decomposition one-step reaction to prepare phenol and cyclohexanone. The preparation method of the polymer-supported NHPI and sulfonic acid bifunctional catalyst comprises the following steps: (1) An organic compound is used as a crosslinking functional group monomer, wherein the crosslinking functional group monomer is one or more of 2-hydroxyacrylate, divinylbenzene, and acrylamide. A sulfonic acid group-containing compound and an initiator are added to a tetrahydrofuran aqueous solution, and the molar ratio of the total amount of the sulfonic acid group-containing compound to the crosslinking functional group monomer is (0.05-5.00):1, and the mixture is stirred until completely dissolved; (2) subjecting the solution obtained in step (1) to a copolymerization reaction under solvent thermal conditions at a temperature of 50 to 150° C. for 12 to 48 hours, obtaining a reaction product a after the reaction is completed, and soaking the product b in water and / or ethanol; (3) evaporating, filtering, washing, and drying the soaked material b obtained in step (2) to obtain a high molecular weight polymer solid c; (4) converting the solid c obtained in step (3) into a proton form by ion exchange in an acid solution to obtain a reaction solution d; (5) subjecting the reaction solution d obtained in step (4) to solid-liquid separation to obtain a solid e; (6) filtering, washing, and drying the solid e obtained in step (5) to obtain a high molecular weight polymer solid f; (7) The solid f obtained in step (6) was added to a dichloromethane-pyridine solution, stirred, and cooled in an ice-water bath. Then, a trimellitic anhydride solution was added thereto, and the mixture was stirred in an ice-water bath and at room temperature, respectively, to obtain a reaction solution g; (8) filtering, washing, and drying the reaction solution g obtained in step (7) to obtain an immobilized acid anhydride polymer solid h; (9) adding the solid h obtained in step (8) to a dichloroethane-pyridine solution, adding hydroxylamine hydrochloride, and refluxing with stirring to obtain a reaction solution i; (10) The reaction solution i obtained in step (9) is filtered, washed, and dried to obtain a polymer-supported NHPI and sulfonic acid bifunctional catalyst f.

2. The use according to claim 1, characterized in that In step (1), the molar ratio of the total amount of the compound containing sulfonic acid groups to the initiator is 1:(0.001~0.1); the initiator is benzoyl peroxide or azobisisobutyronitrile.

3. The use according to claim 1, characterized in that In step (1), the sulfonic acid group-containing compound is one or more of sodium p-styrene sulfonate, sodium vinyl sulfonate, and styrene disulfonic acid; and the molar ratio of the total amount of the sulfonic acid group-containing compound to the crosslinking functional group monomer is (0.1-2.5):

1.

4. The use according to claim 1, characterized in that In step (1), the molar ratio of the total amount of the sulfonic acid group-containing compound to the crosslinking functional group monomer is (0.5-2.0):

1.

5. The use according to claim 1, characterized in that In step (3), the washing is performed by using one or more of the solvents of dichloromethane, N,N-dimethylformamide, dichloroethane, tetrahydrofuran, and ether for 1 to 3 times, the washing temperature is 50 to 90°C, and the washing time is 0.5 to 2 hours. The drying is performed by vacuum drying at a temperature of 50 to 150°C and a time of 12 to 48 hours.

6. The use according to claim 1, characterized in that In step (4), the acid solution is a sulfuric acid solution and / or a hydrochloric acid solution, the concentration of the acid solution is 0.1-2 mol / L, the reaction temperature is 25-80°C, and the reaction time is 12-48 hours; in step (5), the evaporation is rotary evaporation, and the washing or rotary evaporation is performed 5-10 times using one or more of solvents selected from water, ethanol, dichloroethane, ether, and ethanol aqueous solution, the washing or rotary evaporation temperature is 20-90°C, and the washing or rotary evaporation time is 2-5 hours.

7. The use according to claim 1, characterized in that In step (6), the washing is performed 1 to 3 times using one or more of the solvents dichloromethane, N,N-dimethylformamide, dichloroethane, tetrahydrofuran, and ether, the washing temperature is 50 to 90°C, and the washing time is 0.5 to 2 hours. The drying is vacuum drying at a temperature of 50 to 150°C and a time of 12 to 48 hours. In step (7), the cooling time in an ice-water bath is 1 to 3 hours. The chlorotrimellitic anhydride solution is obtained by dissolving chlorotrimellitic anhydride in dichloromethane, and the addition method is dropwise addition. The molar ratio of chlorotrimellitic anhydride to the cross-linking functional group monomer is (0.1 to 1):

1. The stirring time in the ice-water bath is 1 to 5 hours. The stirring time at room temperature is 12 to 48 hours.

8. The use according to claim 1, characterized in that In step (8), the washing is performed by washing with one or more of the solvents ethanol, water, ethanol aqueous solution, dichloromethane, tetrahydrofuran, and ether for 1 to 3 times, the washing temperature is 50 to 90°C, and the washing time is 0.5 to 2 hours. The drying is vacuum drying at a temperature of 50 to 150°C and a time of 12 to 48 hours. In step (9), the molar ratio of hydroxylamine hydrochloride to trimellitic anhydride chloride is (0.1 to 1):1, the reaction temperature is 50 to 150°C, and the time is 12 to 48 hours.

9. The use according to claim 1, characterized in that In step (7) and step (9), the dichloroethane pyridine solution is a solution composed of dichloroethane and pyridine in a volume ratio of 1 to 5:1; in step (10), the washing is performed 1 to 3 times with one or more of the solvents ethanol, water, ethanol aqueous solution, dichloromethane, tetrahydrofuran, and ether, the washing temperature is 50 to 90°C, the washing time is 0.5 to 2 hours, and the drying is vacuum drying at a temperature of 50 to 150°C and a time of 12 to 48 hours.

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