Method for catalyzing decomposition of hydrogen peroxide cyclohexylbenzene

Abstract

The invention provides a method for catalyzing decomposition of hydrogen peroxide cyclohexylbenzene, which comprises the following steps: in the presence of a modified molecular sieve, a raw material containing hydrogen peroxide cyclohexylbenzene is subjected to an acid decomposition reaction, the total acid amount of the modified molecular sieve is greater than or equal to 1160 [mu] mol / g, and the content of B acid accounts for greater than or equal to 65%. The method provided by the invention can be used for preparing phenol and cyclohexanone through high-selectivity acidolysis of cyclohexylbenzene hydroperoxide under high conversion rate, and solves the problems of low conversion rate of cyclohexylbenzene hydroperoxide catalyzed by solid acid or severe heat production under high conversion rate and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of fine chemical industry, and relates to a method for catalytic decomposition of hydrogen peroxide cyclohexylbenzene by modified molecular sieve. BACKGROUND

[0002] Phenol and ketone are important basic chemical raw materials, and their applications involve all aspects of people's livelihood such as clothing, food, shelter and transportation. Among them, phenol and cyclohexanone are the most widely used. Phenol is an important intermediate for the synthesis of plastics, drugs, pesticides, fungicides, preservatives, disinfectants, etc. It is particularly used in the production of polycarbonate, epoxy resin and phenolic resin synthetic materials in the electronics, automobile and electrical appliance industries, and its demand is growing rapidly at a rate of 7%-10% per year in the coming years. Cyclohexanone is mainly used to produce important monomer raw materials such as caprolactam and adipic acid for nylon and polyurethane high polymer materials, and at the same time, cyclohexanone is also an important industrial solvent, and its consumption is large.

[0003] The production of phenol and ketone involves the oxidation process of hydrocarbons, and the traditional technology has environmental protection problems to be solved. Among them, the mainstream production process of cyclohexanone adopts liquid phase oxidation of cyclohexane, which includes four reaction processes of benzene hydrogenation to cyclohexane, cyclohexane oxidation to hydrogen peroxide cyclohexane, hydrogen peroxide cyclohexane decomposition to cyclohexanone and cyclohexanol, and cyclohexanol dehydrogenation to cyclohexanone. The reaction process is long, the conversion rate of oxidation process is low (only 3%-5%), and the product selectivity is poor, which not only causes high energy and material consumption and high cost, but also produces salt-containing and organic-containing wastewater in the oxidation and decomposition processes, and the discharge of three wastes is large, and the environmental protection problem is prominent.

[0004] Phenol is mainly produced by the cumene method, which mainly includes three reaction processes of benzene and propylene alkylation to cumene, cumene oxidation to hydrogen peroxide cumene, and hydrogen peroxide cumene acid decomposition to phenol and co-production of acetone. The existing industrial phenol production technology has the following problems: 1) The co-product acetone has a surplus problem, and the product has low added value; 2) The decomposition process uses concentrated sulfuric acid as a catalyst, which not only causes equipment corrosion, but also produces a large amount of phenolic wastewater, causing environmental pollution.

[0005] The new process for producing phenol and cyclohexanone by cyclohexylbenzene (CHB) method mainly includes two parts of technology: (1) high-efficiency oxidation of CHB to produce hydrogen peroxide cyclohexylbenzene (1-CHBHP); (2) acid decomposition of 1-CHBHP to produce phenol and cyclohexanone. The new process has the characteristics of shorter process, green process and high product added value. Compared with the existing technology, the cyclohexylbenzene method for producing phenol and cyclohexanone has great environmental and economic advantages, and therefore has great theoretical research value and industrial application prospect.

[0006] In recent years, internationally renowned chemical companies such as Shell, UOP, Exxon-Mobil, Stamicarbon, Texaco, and Phillips Petroleum have conducted research and development on related technologies and made some progress. However, due to reasons such as low overall selectivity and the need for further optimization in engineering, they have not yet achieved a breakthrough in industrialization. The academic community has also conducted some research on the catalytic mechanisms of bifunctional catalysts, the activation mechanism of benzylic CH bond oxidation, and solid acid-acid decomposition catalysts.

[0007] The acid decomposition reaction of 1-CHBHP yields phenol and cyclohexanone, but due to the easy deoxygenation of 1-CHBHP to generate the byproduct 1-phenylcyclohexanol, which can further dehydrate under acid catalysts to produce 1-phenylcyclohexene, 6-hydroxyphenylhexanone, and other byproducts. Furthermore, cyclohexanone readily undergoes self-condensation and dehydration under acidic conditions. Therefore, controlling the reaction between acidic sites and the substrate in the acid decomposition reaction is a significant challenge. Sulfuric acid is commonly used as an acid decomposition catalyst due to its mild reaction conditions and high conversion rate, but it also causes wastewater discharge and equipment corrosion. Using solid acids as decomposition catalysts can fundamentally avoid wastewater generation; however, conventional solid acid catalysts such as montmorillonite, silica-alumina oxides, ion exchange resins, heteropoly acids, and molecular sieves exhibit low selectivity and unsatisfactory results. Therefore, developing highly selective solid acid catalysts for the decomposition of 1-CHBHP is crucial for achieving green production processes for phenol and cyclohexanone. Summary of the Invention

[0008] The purpose of this invention is to provide a method for the decomposition of cyclohexylbenzene by hydrogen peroxide catalyzed by modified molecular sieves. The method of this invention can prepare phenol and cyclohexanone by acid hydrolysis of cyclohexylbenzene by hydrogen peroxide with high conversion rate and high selectivity, and solves the problems of low conversion rate and selectivity of cyclohexylbenzene by solid acid catalysis or severe heat generation at high conversion rate.

[0009] Specifically, the present invention provides a method for catalytic decomposition of cyclohexylbenzene containing hydrogen peroxide, comprising subjecting a raw material containing cyclohexylbenzene containing hydrogen peroxide to an acid decomposition reaction in the presence of a modified molecular sieve.

[0010] The modified molecular sieve has a total acid content greater than or equal to 1160 μmol / g, and the proportion of Brønsted acid content is greater than or equal to 65%.

[0011] This invention uses a modified molecular sieve as a catalyst. Leveraging the high selectivity of this catalyst, and using cyclohexylbenzene peroxide as a raw material, reactions such as proton-guided alkyl migration break the peroxy bond, allowing the phenyl group to migrate to one of the oxygen atoms, subsequently decomposing to generate phenol and cyclohexanone. By controlling the total acid content and the corresponding Brønsted acid ratio of the modified molecular sieve within the aforementioned range under different molecular sieve modification conditions, excessive heat generation and highly selective and efficient acidolysis can be achieved.

[0012] In this invention, the total acid content of the modified molecular sieve was obtained by ammonia gas temperature-programmed desorption test.

[0013] In some embodiments, the total acidity of the modified molecular sieve is 1180 μmol / g, 1200 μmol / g, 1210 μmol / g, 1230 μmol / g, 1250 μmol / g, 1270 μmol / g, 1290 μmol / g, 1300 μmol / g, 1310 μmol / g, 1330 μmol / g, 1350 μmol / g, 1370 μmol / g, 1390 μmol / g, 1400 μmol / g, 1410 μmol / g, 1430 μmol / g, 1450 μmol / g, 1470 μmol / g, etc. The total acid content of the modified molecular sieve is 1160 μmol / g to 1700 μmol / g. In some embodiments, the total acid content of the modified molecular sieve is 1200 μmol / g to 1500 μmol / g. The values ​​are 1490 μmol / g, 1500 μmol / g, 1510 μmol / g, 1530 μmol / g, 1550 μmol / g, 1570 μmol / g, 1590 μmol / g, 1600 μmol / g, 1630 μmol / g, 1650 μmol / g, 1670 μmol / g, 1700 μmol / g, 1750 μmol / g, 1800 μmol / g, 1850 μmol / g, 1900 μmol / g, 1950 μmol / g, 2000 μmol / g, or any value between them. In some embodiments, the total acid content of the modified molecular sieve is 1160 μmol / g to 1700 μmol / g. In some embodiments, the total acid content of the modified molecular sieve is 1200 μmol / g to 1500 μmol / g.

[0014] In some embodiments, the modified molecular sieve contains 66%-85% Brønsted acid, for example, 66.5%, 67%, 67.5%, 68%, 68.5%, 69%, 69.5%, 70%, 70.5%, 71%, 71.5%, 72%, 72.5%, 73%, 73.5%, 74%, 74.5%, 75%, 75.5%, 76%, 76.5%, 77%, 77.5%, 78%, 78.5%, 79%, 79.5%, 80%, 80.5%, 81%, 81.5%, 82%, 82.5%, 83%, 83.5%, 84%, 84.5%, or any value between them.

[0015] In this invention, the percentage of Brønsted acid content is Brønsted acid content / total acid content * 100%.

[0016] In some embodiments, the modified molecular sieve contains 67%-75% Brønsted acid. A higher Brønsted acid content is beneficial for improved selectivity.

[0017] In this invention, the Brønsted acid content of the modified molecular sieve is determined by pyridine adsorption infrared spectroscopy.

[0018] In some embodiments, the amount of β-acid in the modified molecular sieve is 800 μmol / g to 1000 μmol / g, for example, 810 μmol / g, 820 μmol / g, 830 μmol / g, 840 μmol / g, 850 μmol / g, 860 μmol / g, 870 μmol / g, 880 μmol / g, 890 μmol / g, 900 μmol / g, 910 μmol / g, 920 μmol / g, 930 μmol / g, 940 μmol / g, 950 μmol / g, 960 μmol / g, 970 μmol / g, 980 μmol / g, 990 μmol / g, or any value between them. In some embodiments, the amount of β-acid in the modified molecular sieve is 850 μmol / g to 950 μmol / g.

[0019] In some embodiments, the silica-to-alumina ratio of the modified molecular sieve is 4-50, for example, 4.3, 4.5, 4.7, 5.0, 5.3, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 23, 25, 27, 30, 33, 35, 37, 40, 43, 45, 47, or any value between them. In some embodiments, the silica-to-alumina ratio of the modified molecular sieve is 5.5-20.

[0020] In some embodiments, the pore size of the modified molecular sieve is 3.0 nm to 5.0 nm, for example, 3.1 nm, 3.2 nm, 3.3 nm, 3.4 nm, 3.5 nm, 3.6 nm, 3.7 nm, 3.8 nm, 3.9 nm, 4.0 nm, 4.1 nm, 4.2 nm, 4.3 nm, 4.4 nm, 4.5 nm, 4.6 nm, 4.7 nm, 4.8 nm, 4.9 nm, or any value between them. In some embodiments, the pore size of the modified molecular sieve is 3.5 nm to 4.5 nm, as determined by a low-temperature nitrogen adsorption method. When the pore size of the modified molecular sieve is too low, cyclohexylbenzene peroxide is difficult to diffuse inside the molecular sieve (for example, the diffusion allowance parameter of Y molecular sieve is...). The length of the cyclohexylbenzene molecule is approximately Width When the pore size of the modified molecular sieve is too large, it will cause the modified molecular sieve to lose its confinement effect, which will affect the selectivity of the modified molecular sieve. The modified molecular sieve of the present invention has undergone appropriate pore enlargement on the basis of the original molecular sieve. While increasing the total acid content and Brønsted acid sites, it has basically retained the original pore structure, making it easier for cyclohexylbenzene peroxide to enter the interior of the molecular sieve and enhancing the acidity of the molecular sieve. In this way, it can better reduce excessive heat generation and achieve high selectivity and high efficiency acidolysis.

[0021] In this invention, the pore size of the modified molecular sieve is determined using a low-temperature nitrogen adsorption method.

[0022] In some embodiments, the modified molecular sieve has a micropore volume (V0). micro The micropore volume is 0.1 mL / g to 0.5 mL / g, for example, 0.15 mL / g, 0.2 mL / g, 0.25 mL / g, 0.3 mL / g, 0.35 mL / g, 0.4 mL / g, 0.45 mL / g, or any value between them. In some embodiments, the micropore volume is 0.2 mL / g to 0.4 mL / g.

[0023] In some embodiments, the modified molecular sieve has a mesopore volume (V) meso The value is 0.01 mL / g to 0.05 mL / g, for example, 0.015 mL / g, 0.02 mL / g, 0.025 mL / g, 0.03 mL / g, 0.035 mL / g, 0.04 mL / g, 0.045 mL / g or any value between them.

[0024] In some embodiments, the method for preparing modified molecular sieves includes treating the original molecular sieve with alkali and acid solutions, followed by calcining the treated product.

[0025] In some embodiments, the method for preparing the modified molecular sieve includes the following steps:

[0026] S1: Mix the original molecular sieve with alkaline solution to perform desilication treatment and obtain the desilication product;

[0027] S2: Mix the desilication product with acid solution and perform dealuminization treatment to obtain the dealuminization product;

[0028] S3: The dealuminized product is calcined to obtain the modified molecular sieve.

[0029] In some embodiments, in step S1, the alkaline substance in the alkaline solution is selected from one or more inorganic and organic bases.

[0030] In some embodiments, in step S1, the alkaline substance in the alkaline solution is selected from at least one of alkyl ammonium hydroxide and inorganic bases.

[0031] In some embodiments, the alkaline substance is selected from tetra-C1-C6 alkylammonium hydroxide. In some embodiments, the alkylammonium hydroxide is selected from one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide. In some embodiments, the inorganic base is selected from one or more of sodium hydroxide, potassium hydroxide, and ammonia water.

[0032] In some embodiments, the concentration of the alkaline substance in the alkaline solution is 0.05 mol / L to 3 mol / L, for example, 0.07 mol / L, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, 1.0 mol / L, 2.3 mol / L, 2.5 mol / L, 2.7 mol / L, or any value between them. In some embodiments, the concentration of the alkaline substance is 0.1 mol / L to 1.5 mol / L. The alkaline solution slightly expands the pores of the original molecular sieve, such as Y-type molecular sieve, while increasing the number of Brønsted acid sites, making it easier for cyclohexylbenzene peroxide to enter the interior of the molecular sieve and enhancing the acidity of the molecular sieve. However, excessively high concentrations of alkaline solution can lead to excessive pore expansion, causing the molecular sieve to lose its confinement effect, thereby reducing selectivity.

[0033] In some embodiments, the mass of the alkaline solution is 1-5 times the mass of the original molecular sieve, for example, 1.5 times, 2 times, 3 times, 3.5 times, 4 times, or 4.5 times. In some embodiments, the mass of the alkaline solution is 2-4 times the mass of the original molecular sieve.

[0034] In some embodiments, the mass ratio of the alkaline solution to the original molecular sieve is 1-5, for example, 1.5, 2, 3, 3.5, 4, or 4.5. In some embodiments, the mass ratio of the alkaline solution to the original molecular sieve is 2-4.

[0035] In some embodiments, the temperature of the desilication process in step S1 is 50°C-95°C, for example, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or any value between them. In some embodiments, the temperature of the desilication process is 55°C-75°C.

[0036] In some embodiments, the desilication treatment time in step S1 is 5 min to 90 min, for example, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, or any value between them. In some embodiments, the desilication treatment time is 10 min to 60 min.

[0037] In some embodiments, in step S2, the acid in the acid solution is selected from at least one of inorganic acids, organic acids, and inorganic ammonium salts. In some embodiments, the acid in the acid solution is selected from one or more of C1-C6 organic acids, hydrochloric acid, sulfuric acid, nitric acid, ammonium chloride, and ammonium bromide, preferably ammonium chloride. When the acid solution is too acidic, it will cause a certain degree of collapse of the pores. Although it can enrich the surface acidic sites, it will make it more difficult for cyclohexylbenzene peroxide to enter the interior of the pores, and it will only react on the surface, thus affecting the performance of the molecular sieve.

[0038] In some embodiments, the concentration of the acid in the acid solution is 0.1 mol / L to 5 mol / L, for example, 0.07 mol / L, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.7 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.7 mol / L, 1.9 mol / L, 1.0 mol / L, 2.3 mol / L, 2.5 mol / L, 2.7 mol / L, 3.0 mol / L, 3.3 mol / L, 3.5 mol / L, 3.7 mol / L, 4.0 mol / L, 4.3 mol / L, 4.5 mol / L, 4.7 mol / L, or any value between them. In some embodiments, the concentration of the acid is 0.5 mol / L to 3 mol / L.

[0039] In some embodiments, in step S2, the mass of the acid solution is 1-15 times the mass of the original molecular sieve, for example, 1.5 times, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 13 times, 14 times, or any value between them. In some embodiments, the mass of the acid solution is 2-10 times the mass of the original molecular sieve.

[0040] In some embodiments, the mass ratio of the acid solution to the original molecular sieve is 1-15, for example, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or any value between them. In some embodiments, the mass ratio of the acid solution to the original molecular sieve is 2-10.

[0041] In some embodiments, the temperature of the dealuminization process in step S2 is 50°C-95°C, for example, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or any value between them. In some embodiments, the temperature of the dealuminization process is 70°C-90°C.

[0042] In some embodiments, the dealuminization process in step S2 takes 3 to 20 hours, for example, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 hours, or any value between them. In some embodiments, the dealuminization process takes 6 to 12 hours.

[0043] In some embodiments, the calcination temperature in step S3 is 400℃-600℃, for example, 430℃, 450℃, 470℃, 500℃, 530℃, 550℃, or 570℃. In some embodiments, the calcination temperature is 450℃-550℃.

[0044] In some embodiments, the roasting time in step S3 is 1 hour to 10 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or 9 hours. In some embodiments, the roasting time is 3 hours to 6 hours.

[0045] In some embodiments, in step S3, the calcination is carried out in an air atmosphere.

[0046] In some embodiments, the original molecular sieve is selected from one or more of ZSM-5 molecular sieve, Beta molecular sieve, and Y-type molecular sieve.

[0047] In some embodiments, the raw material containing hydrogen peroxide-containing cyclohexylbenzene is selected from a solution generated during the oxidation of cyclohexylbenzene. In some embodiments, the raw material is a cyclohexylbenzene solution containing hydrogen peroxide-containing cyclohexylbenzene. In some embodiments, the mass content of hydrogen peroxide-containing cyclohexylbenzene in the solution is 10%-30%, for example, 15%, 20%, or 25%.

[0048] In some embodiments, the raw material containing hydrogen peroxide cyclohexylbenzene undergoes steps such as vacuum distillation to remove as much moisture as possible from the raw material.

[0049] In some embodiments, the modified molecular sieve is 0.5%-5% of the mass of the raw material containing hydrogen peroxide cyclohexylbenzene, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 4.5%. In some embodiments, the modified molecular sieve is 1%-2% of the mass of the raw material containing hydrogen peroxide cyclohexylbenzene.

[0050] In some embodiments, the acid decomposition reaction is carried out at a temperature of 40°C-80°C, for example, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, or 75°C. In some embodiments, the acid decomposition reaction is carried out at a temperature of 50°C-60°C.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) The reaction conditions of the method described in this invention are mild, avoiding the acidic wastewater treatment and strong heat removal processes required in sulfuric acid industrial applications. Furthermore, as a heterogeneous catalyst, molecular sieves are easier to separate from the product. Due to their good structural stability, molecular sieves offer better regenerability compared to solid acids such as resins. Additionally, the modified molecular sieves contain moderately strong acidic sites, which, compared to sulfuric acid, can effectively reduce the condensation ratio of cyclohexanone while catalyzing the acidolysis of cyclohexylbenzene with hydrogen peroxide, thus improving atom utilization. This method has promising prospects for industrialization.

[0053] (2) Under optimal molecular sieve modification conditions, the conversion rate of hydrogen peroxide cyclohexylbenzene can reach over 97%, and the selectivity of phenol and cyclohexanone can both reach 90%. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this disclosure. Such structures and techniques have also been described in many publications.

[0055] The original molecular sieves used in the embodiments and comparative examples of this invention are all commercial products. The initial silica-to-alumina ratio of the Beta molecular sieve is 30, and the initial silica-to-alumina ratio of the Y molecular sieve is 9.

[0056] In this invention, the pore structure parameters of the molecular sieve, such as pore size, micropore volume, and mesopore volume, are obtained by measuring the nitrogen adsorption isotherm of the modified molecular sieve using a fully automated specific surface area and porosity analyzer (McMed Instruments, TriStar 3000 and 3Flex). The pore distribution of the material is obtained using the HK method, Dubinin method, and density function method.

[0057] In this invention, a temperature-programmed chemisorption analyzer (AutoChem II2950 / 2920, Micron Instruments, USA) and a Fourier transform infrared spectrometer (Thermofisher Scientific, Nicolet iS50) were used to determine the acid content of the molecular sieve and the ratio of Brønsted acid to Lewis acid.

[0058] In the NH3-TPD chemisorption-desorption curve, the adsorption temperature program ranges from 100℃ to 550℃, with ammonia adsorption at 60℃ for 30 minutes, and the desorption temperature program ranges from 20℃ to 640℃.

[0059] In a Fourier transform infrared spectrometer, at 1600 cm⁻¹ -1 The characteristic peak appearing nearby is a characteristic peak of Brønsted acid, at 1440 cm⁻¹. -1 The characteristic peaks appearing nearby are characteristic peaks of L-acid.

[0060] The present invention will now be described in detail through examples and comparative examples.

[0061] Example 1

[0062] Preparation of modified molecular sieves:

[0063] Y-type molecular sieves were obtained by treating them with TPAOH (tetrapropylammonium hydroxide) at a concentration of 0.2 mol / L at 60℃ for 30 minutes. The mass ratio of TPAOH alkali solution to Y-type molecular sieves was 2:1.

[0064] The modified molecular sieve precursor was obtained by treating the above-mentioned alkali-treated Y-type molecular sieve with ammonium chloride solution at a concentration of 1 mol / L at 80℃ for 12 hours. The mass ratio of ammonium chloride solution to Y-type molecular sieve was 8:1.

[0065] The modified molecular sieve precursor treated above was calcined in a muffle furnace at 500°C for 4 hours in air atmosphere to obtain the modified molecular sieve. The characteristics of the obtained modified molecular sieve are detailed in Table 1.

[0066] Catalytic decomposition of cyclohexylbenzene by hydrogen peroxide:

[0067] A three-necked flask was used as the reactor, and a modified molecular sieve was used as the catalyst. A cyclohexylbenzene solution containing approximately 20% (by mass) of hydrogen peroxide cyclohexylbenzene was added to the flask. The mass ratio of the modified molecular sieve to the cyclohexylbenzene solution was 1.5%. The mixture was stirred at a constant temperature of 55°C, and the hydrogen peroxide cyclohexylbenzene underwent a decomposition reaction under acidic molecular sieve catalysis to yield phenol and cyclohexanone.

[0068] The peroxide conversion rate and the selectivity of phenol and cyclohexanone are shown in Table 2.

[0069] Example 2

[0070] The only difference from Example 1 is that the acid used is concentrated nitric acid, and the mass ratio of concentrated nitric acid to molecular sieve is 4:1. All other conditions and parameters are exactly the same as in Example 1.

[0071] The characteristics of the obtained modified molecular sieves are detailed in Table 1. The peroxide conversion and the selectivity for phenol and cyclohexanone are shown in Table 2.

[0072] Example 3

[0073] The only difference from Example 1 is that the calcination temperature used is 550°C, while the other conditions and parameters are exactly the same as in Example 1.

[0074] The characteristics of the obtained modified molecular sieves are detailed in Table 1. The peroxide conversion and the selectivity for phenol and cyclohexanone are shown in Table 2.

[0075] Example 4

[0076] The only difference from Example 1 is that the acid used is dilute nitric acid with a concentration of 1 mol / L, and the mass ratio of dilute nitric acid to molecular sieve is 4:1. All other conditions and parameters are exactly the same as in Example 1.

[0077] The characteristics of the obtained modified molecular sieves are detailed in Table 1. The peroxide conversion and the selectivity for phenol and cyclohexanone are shown in Table 2.

[0078] Example 5

[0079] The only difference from Example 1 is that the sample was first treated with concentrated nitric acid, then with an alkali, and finally hydrogenated in a 1 mol / L ammonium chloride solution at 80°C for 12 hours. The mass ratio of concentrated nitric acid to Y-type molecular sieve was 4:1. All other conditions and parameters were exactly the same as in Example 1.

[0080] The characteristics of the obtained modified molecular sieves are detailed in Table 1. The peroxide conversion and the selectivity for phenol and cyclohexanone are shown in Table 2.

[0081] Example 6

[0082] The only difference from Example 1 is that the alkaline solution used is TEAOH (tetraethylammonium hydroxide), while the other conditions and parameters are exactly the same as in Example 1.

[0083] The characteristics of the obtained modified molecular sieves are detailed in Table 1. The peroxide conversion and the selectivity for phenol and cyclohexanone are shown in Table 2.

[0084] Example 7

[0085] The only difference from Example 1 is that the concentration of TPAOH is 2 mol / L, while the other conditions and parameters are exactly the same as in Example 1.

[0086] The characteristics of the obtained modified molecular sieves are detailed in Table 1. The peroxide conversion and the selectivity for phenol and cyclohexanone are shown in Table 2.

[0087] Comparative Example 1

[0088] The only difference from Example 1 is that there is no alkali treatment step; all other conditions and parameters are exactly the same as in Example 1.

[0089] The characteristics of the obtained modified molecular sieves are detailed in Table 1. The peroxide conversion and the selectivity for phenol and cyclohexanone are shown in Table 2.

[0090] Comparative Example 2

[0091] The only difference from Example 1 is that the raw material for modification is a Beta-type molecular sieve, the acid used is concentrated nitric acid, and the mass ratio of concentrated nitric acid to molecular sieve is 4:1. All other conditions and parameters are exactly the same as in Example 1.

[0092] All other conditions and parameters are exactly the same as in Example 1.

[0093] The characteristics of the obtained modified molecular sieves are detailed in Table 1. The peroxide conversion and the selectivity for phenol and cyclohexanone are shown in Table 2.

[0094] Table 1

[0095]

[0096] Performance testing:

[0097] The conversion rates of hydrogen peroxide to cyclohexylbenzene, the selectivity of phenol and cyclohexanone, and the highest temperature reached during the reaction in the examples and comparative examples after 4 hours are shown in Table 2.

[0098] Table 2

[0099]

[0100]

[0101] As can be seen from Table 2, under preferred conditions, the modified molecular sieve catalytic decomposition method for hydrogen peroxide cyclohexylbenzene described in this invention achieves a hydrogen peroxide cyclohexylbenzene conversion rate of over 97% after 4 hours of reaction, while the selectivity of phenol and cyclohexanone can both reach over 90%. At the same time, the exothermic reaction phenomenon is improved, and the maximum temperature in the reaction system does not exceed 60°C at an ambient heating temperature of 55°C.

[0102] As can be seen from the comparison between Example 1 and Comparative Example 2, the modified Y molecular sieve has better product selectivity while maintaining a comparable conversion rate compared to the modified Beta molecular sieve.

[0103] As can be seen from the comparison between Example 1 and Example 2, treatment with strong acid (such as concentrated nitric acid) will cause the pores to collapse to a certain extent, making it more difficult for hydrogen peroxide cyclohexylbenzene to enter the pores and react only on the surface. Therefore, the selectivity of the originally highly reactive Y molecular sieve will be affected to a certain extent after treatment with strong acid.

[0104] A comparison of Examples 1 and 3 shows that the temperature during the calcination process has a certain impact on the properties of the molecular sieve, causing the overall acidity of the molecular sieve to decrease, thereby affecting the performance of the molecular sieve.

[0105] As can be seen from the comparison of Examples 1 and 5 and Comparative Example 1, not performing alkali treatment or performing acid treatment first and then alkali treatment will affect the overall acid content of the molecular sieve and thus affect the performance of the molecular sieve.

[0106] The comparison between Examples 1, 6, and 7 shows that the alkaline solution used in the modification of molecular sieves has a significant impact on the properties of the modified molecular sieves. Longer alkaline treatment time, more concentrated alkaline solution, or replacing TPAOH with TEAOH will cause more drastic structural changes, resulting in excessive pore expansion of the molecular sieve. This will cause the molecular sieve to lose its confinement effect and thus affect its performance.

[0107] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for catalyzing decomposition of hydrogen peroxide cyclohexylbenzene, comprising subjecting a raw material containing hydrogen peroxide cyclohexylbenzene to an acid decomposition reaction in the presence of a modified molecular sieve, wherein the total acid amount of the modified molecular sieve is greater than or equal to 1160 μmol / g, and the proportion of B acid content is greater than or equal to 65%.

2. The method of claim 1, wherein, the total acid amount of the modified molecular sieve is 1160 μmol / g-1700 μmol / g, preferably 1200 μmol / g-1500 μmol / g; and / or the proportion of B acid content in the modified molecular sieve is 66%-85%, preferably 67%-75%; and / or the B acid amount of the modified molecular sieve is 800 μmol / g-1000 μmol / g, preferably 850 μmol / g-950 μmol / g; and / or the silicon-aluminum ratio of the modified molecular sieve is 4-50, preferably 5.5-20.

3. The method according to claim 1 or 2, characterized in that, the pore size of the modified molecular sieve is 3.0 nm-5.0 nm, preferably 3.5 nm-4.5 nm; and / or the micropore volume of the modified molecular sieve is 0.1 mL / g-0.5 mL / g, preferably 0.2 mL / g-0.4 mL / g; and / or the mesopore volume of the modified molecular sieve is 0.01 mL / g-0.05 mL / g.

4. The method according to any one of claims 1-3, characterized in that, the preparation method of the modified molecular sieve comprises treating the original molecular sieve with a lye and an acid liquor, and then calcining the treatment product, and preferably comprises the following steps: S1: mixing the original molecular sieve with a lye to perform desilication treatment, to obtain a desilication treatment product; S2: mixing the desilication treatment product with an acid liquor to perform dealumination treatment, to obtain a dealumination treatment product; S3: calcining the dealumination treatment product to obtain the modified molecular sieve.

5. The method of claim 4, wherein, In step S1, the alkaline substance in the lye is selected from one or more of inorganic bases and organic bases; preferably at least one of alkylammonium hydroxide and inorganic bases; more preferably, the alkylammonium hydroxide is selected from one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide, and the inorganic base is selected from one or more of sodium hydroxide, potassium hydroxide and ammonia; and / or the concentration of the alkaline substance in the lye is 0.05 mol / L-3 mol / L, preferably 0.1 mol / L-1.5 mol / L; and / or the mass of the lye is 1-5 times, preferably 2-4 times, the mass of the original molecular sieve; and / or the temperature of the desilication treatment is 50°C-95°C, preferably 55°C-75°C; and / or the time of the desilication treatment is 5 min-90 min, preferably 10 min-60 min.

6. The method according to claim 4 or 5, characterized in that, In step S2, the acid in the acid liquor is selected from at least one of inorganic acids, organic acids and inorganic ammonium salts, preferably one or more of C1-C6 organic acids, hydrochloric acid, sulfuric acid, nitric acid, ammonium chloride and ammonium bromide, and is preferably ammonium chloride; and / or the concentration of the acid in the acid liquor is 0.1 mol / L-5 mol / L, preferably 0.5 mol / L-3 mol / L; and / or The mass of the acid solution is 1-15 times, preferably 2-10 times, of the mass of the original molecular sieve; and / or The temperature of the dealumination treatment is 50-95℃, preferably 70-90℃; and / or The time of the dealumination treatment is 3-20 hours, preferably 6-12 hours.

7. The method according to any one of claims 4-5, characterized in that, In step S3, the calcination temperature is 400-600℃, preferably 450-550℃; and / or The time of the calcination is 1-10 hours, preferably 3-6 hours; and / or The calcination is carried out in an air atmosphere.

8. The method according to any one of claims 1-7, characterized in that, The original molecular sieve is selected from one or more of ZSM-5 molecular sieve, Beta molecular sieve and Y-type molecular sieve.

9. The method according to any one of claims 1-8, characterized in that, The raw material containing hydrogen peroxide cyclohexylbenzene is selected from a solution produced in a cyclohexylbenzene oxidation process, preferably the raw material is a cyclohexylbenzene solution containing hydrogen peroxide cyclohexylbenzene, more preferably in the solution, the mass content of hydrogen peroxide cyclohexylbenzene is 10%-30%; and / or The modified molecular sieve is 0.5%-5%, preferably 1%-2%, of the mass of the raw material containing hydrogen peroxide cyclohexylbenzene.

10. The method according to any one of claims 1-9, characterized in that, The temperature of the acid decomposition reaction is 40-80℃, preferably 50-60℃.

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