Resin type catalyst with nanosphere structure, preparation method and application of resin type catalyst, and preparation method of caprolactam

Abstract

The invention discloses a resin type catalyst with a nanosphere structure as well as a preparation method and application of the resin type catalyst and a preparation method of caprolactam. The resin type catalyst with the nanosphere structure comprises polystyrene-divinyl benzene nanosphere structure resin and a sulfonic acid group, the sulfonic acid group is located on a benzene ring of the polystyrene-divinyl benzene nanosphere structure resin, and the catalyst is suitable for preparing caprolactam through Beckmann liquid phase rearrangement. And excellent raw material conversion rate and product selectivity can be shown.

Description

Technical Field

[0001] The invention relates to the technical field of Beckmann liquid phase rearrangement reaction catalysis, and in particular to a resin-type catalyst with a nanosphere structure, a preparation method and application thereof, and a method for preparing caprolactam. Background Art

[0002] Caprolactam is an important chemical raw material monomer for the production of synthetic fibers and engineering plastics. The technical routes for the industrial production of caprolactam are mainly divided into two types: gas phase and liquid phase. Among them, the liquid phase Beckmann rearrangement process with fuming sulfuric acid as a catalyst is the most widely used production route. In this process, fuming sulfuric acid is used as a catalyst, and the raw material cyclohexanone oxime undergoes a Beckmann rearrangement reaction to obtain the target product caprolactam. Ammonia is also introduced into the reaction to neutralize a large amount of strong acid in the reaction system and produce ammonium sulfate with low economic value as a by-product. The process conditions are mature, and the raw material conversion rate and product selectivity are high. However, there are defects such as concentrated sulfuric acid corroding production equipment and low economic value of by-products, which does not conform to the concept of sustainable development.

[0003] Different silica-alumina materials, zeolites and mixed oxides have been used as catalysts in the gas-phase Beckmann rearrangement reaction. However, the gas-phase Beckmann rearrangement is usually energy-intensive because it usually needs to be carried out at temperatures above 300°C, which also causes the catalyst to deactivate rapidly due to coking. Although the liquid-phase Beckmann rearrangement process can be carried out under milder reaction conditions and the target amide is easily obtained, the current strong acid cation exchange resin catalyst does not perform well in this reaction. Summary of the invention

[0004] The present application provides a resin-type catalyst with a nanosphere structure, a preparation method and an application thereof. The resin-type catalyst with a nanosphere structure provided by the present application is suitable for the preparation of caprolactam by Beckmann liquid phase rearrangement, and can show excellent raw material conversion rate and product selectivity.

[0005] In a first aspect, an embodiment of the present application provides a resin-type catalyst having a nanosphere structure, comprising a polystyrene-divinylbenzene nanosphere structure resin and a sulfonic acid group, wherein the sulfonic acid group is located on the benzene ring of the polystyrene-divinylbenzene nanosphere structure resin.

[0006] In some embodiments, the resin-type catalyst has a mesoporous structure, and the specific surface area of ​​the resin-type catalyst is 9-13 m2·g -1 , pore volume is 0.01-0.02cm 3 ·g -1 .

[0007] In some embodiments, the thermal decomposition temperature of the resin-type catalyst having a nanosphere structure is greater than 200°C.

[0008] In a second aspect, the present invention provides a method for preparing a resin-type catalyst having a nanosphere structure, comprising the following steps:

[0009] (1) fully mixing styrene monomer, divinylbenzene, a stabilizer, an initiator, a pore-forming agent and deionized water, and stirring at a constant temperature and in an inert gas atmosphere to obtain a polystyrene-divinylbenzene nanosphere structure resin;

[0010] (2) drying the polystyrene-divinylbenzene nanosphere structure resin, adding the dried polystyrene-divinylbenzene nanosphere structure resin into an organic solvent to fully swell it, and then adding a sulfonating agent to incorporate sulfonic acid groups into the polystyrene-divinylbenzene nanosphere structure resin;

[0011] (3) After filtration, washing and high-temperature drying, the resin-type catalyst with the nanosphere structure is obtained.

[0012] In some embodiments, the amount of divinylbenzene added in step (1) is 10%-30% of the amount of styrene added, calculated by added volume.

[0013] In some embodiments, in step (2), the sulfonation reagent includes at least one of concentrated sulfuric acid and chlorosulfonic acid.

[0014] In some embodiments, in step (1), the stabilizer includes polyvinyl pyrrolidone, the initiator includes potassium persulfate, and the pore-forming agent includes at least one of toluene and n-heptane; in step (2), the organic solvent includes at least one of n-hexane, ethylene dichloride, acetone, dimethylformamide and toluene.

[0015] In a third aspect, an embodiment of the present application provides an application of a resin-type catalyst having a nanosphere structure in a Beckmann liquid phase rearrangement reaction.

[0016] In a fourth aspect, an embodiment of the present application provides a method for preparing caprolactam, comprising the following steps: using cyclohexanone oxime as a reaction raw material and dimethyl sulfoxide as a reaction solvent, performing a Beckmann reaction under the catalytic action of a resin-type catalyst with a nanosphere structure to obtain caprolactam.

[0017] In some embodiments, the reaction temperature is 130-150°C.

[0018] In some embodiments, the resin catalyst having a nanosphere structure is added in an amount of 37.5% to 75% of the cyclohexanone oxime by mass percentage.

[0019] It can be seen from the above technical solution that this specification provides a resin-type catalyst with a nanosphere structure, which is suitable for preparing caprolactam by Beckmann liquid phase rearrangement and can show excellent raw material conversion rate and product selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 The Fourier infrared spectrum of the resin-type catalyst with nanosphere structure provided by some embodiments of the present application is shown;

[0022] Figure 2A The X-ray photoelectron spectrum of the resin-type catalyst with nanosphere structure provided by some embodiments of the present application is shown;

[0023] Figure 2B Shows Figure 2A The X-ray photoelectron spectrum corresponding to C1s in the figure;

[0024] Figure 2C Shows Figure 2A The corresponding X-ray photoelectron spectrum at S2p in the figure;

[0025] Figure 3 A schematic diagram of thermogravimetric analysis of a resin-type catalyst having a nanosphere structure provided in some embodiments of the present application is shown;

[0026] Figure 4A The scanning electron microscope images of the catalysts prepared in some embodiments of the present application are shown;

[0027] Figure 4B The scanning electron microscope images of the catalysts prepared in some embodiments of the present application are shown;

[0028] Figure 4C The scanning electron microscope images of the catalysts prepared in some embodiments of the present application are shown;

[0029] Figure 4D The scanning electron microscope images of the catalysts prepared in some embodiments of the present application are shown;

[0030] Figure 5 Transmission electron microscopy images of catalysts prepared in some examples of the present application are shown. DETAILED DESCRIPTION

[0031] In order to facilitate the understanding of this specification, the specification will be described more fully below with reference to the relevant drawings. The preferred embodiments of this specification are given in the drawings. However, this specification can be implemented in many different forms without departing from the core spirit of this specification and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of this specification more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this specification belongs. The terms used herein in this specification are only for the purpose of describing specific embodiments and are not intended to limit this specification. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0033] In a first aspect, an embodiment of the present application provides a resin-type catalyst having a nanosphere structure, comprising a polystyrene-divinylbenzene nanosphere structure resin and a sulfonic acid group, wherein the sulfonic acid group is located on the benzene ring of the polystyrene-divinylbenzene nanosphere structure resin.

[0034] Figure 1 The Fourier transform infrared spectrum of the resin-type catalyst with nanosphere structure provided in some embodiments of the present application. Figure 1 As shown, 1600cm -1 and 1448cm -1 The peak at 1035 cm is the vibration of the C=C skeleton of the benzene ring. -1 The band at 1216cm belongs to CS vibration. -1 and 1161cm -1 The frequency bands at are the asymmetric and symmetric stretching signals of the sulfonic acid group O=S=O bond, respectively. These results indicate that the sulfonic acid group has been successfully introduced into the aromatic ring of the polystyrene-divinylbenzene nanosphere structured resin.

[0035] Figure 2A-2C The X-ray photoelectron spectrum of the resin-type catalyst with nanosphere structure provided in some embodiments of the present application. Figure 2A-2C As shown, characteristic signals of C, S and O elements in the sample can be observed. The S2p and S2s peaks at 169.1eV and 232.1eV are related to SO and S=O bonds; the spectrum of C 1s shows two binding energies, peaks at 284.8eV and 286.4eV, which are related to CC and CS bonds, respectively. The above results indicate that sulfonic acid groups exist in the resin-type catalyst with nanosphere structure, which is consistent with the Fourier transform infrared spectroscopy results.

[0036] In some embodiments of the present application, the volume ratio of divinylbenzene to styrene during the synthesis of the polystyrene-divinylbenzene nanosphere structure resin is 10%-30%.

[0037] In some embodiments of the present application, a mesoporous structure exists in the resin-type catalyst, and the specific surface area of ​​the resin-type catalyst is 9-13 m 2 ·g -1 , pore volume is 0.01-0.02cm 3 ·g -1 .

[0038] The resin catalyst provided in the embodiment of the present application has a nanosphere structure, the diameter of the nanosphere is between 100-500 nanometers, and the resin catalyst has mesopores, the diameter of the mesopores is in the range of 10-30nm, for example, the diameter of the mesopores can be 10nm, 15nm, 20nm, 25nm, 30nm, or a value between any two of the above pore diameters. The resin catalyst was subjected to a nitrogen adsorption and desorption test (BET test), and its specific surface area was measured to be 9-13m 2 ·g -1 The range, for example, can be 9m 2 ·g -1 、10m 2 ·g -1 、11m 2 ·g -1 、12m 2 ·g -1 、13m 2 ·g -1 , or any value between any two of the above specific surface area values. In addition, the pore volume of the resin-type catalyst is 0.01-0.02cm 3 ·g -1 The range, for example, can be 0.01 cm 3 ·g -1 、0.012cm 3 ·g -1 、0.014cm 3 ·g -1 、0.016cm 3 ·g -1 、0.018cm 3 ·g -1 、0.02cm 3 ·g -1 , or any value between any two of the above pore volume values.

[0039] It can be seen that the interior of the resin-type catalyst presents a loose porous structure, which can accommodate a large amount of gas and provide numerous active adsorption sites, thus showing good catalytic activity.

[0040] Figure 3 Schematic diagram of thermogravimetric analysis (TG) of a resin-type catalyst having a nanosphere structure provided in some embodiments of the present application. Figure 3 As shown, the mass loss observed at 200°C at first corresponds to the elimination of physically adsorbed molecular water; then, the mass loss occurring in the range of 200-400°C corresponds to the decomposition of the sulfonic acid groups; and the subsequent mass loss mainly corresponds to the collapse of the polymer backbone. The resin-type catalyst with a nanosphere structure provided in the embodiment of the present application, the sulfonic acid groups present thereon all exhibit a high thermal decomposition temperature exceeding 200°C, which exceeds the appropriate temperature range for the liquid-phase Beckmann rearrangement, indicating that the resin-type catalyst with a nanosphere structure provided in the embodiment of the present application can be applied to the liquid-phase Beckmann rearrangement reaction.

[0041] In a second aspect, the present invention provides a method for preparing a resin-type catalyst having a nanosphere structure, comprising the following steps:

[0042] (1) fully mixing styrene monomer, divinylbenzene, a stabilizer, an initiator, a pore-forming agent and deionized water, and stirring at a constant temperature and in an inert gas atmosphere to obtain a polystyrene-divinylbenzene nanosphere structure resin;

[0043] (2) drying the polystyrene-divinylbenzene nanosphere structure resin, adding the dried polystyrene-divinylbenzene nanosphere structure resin into an organic solvent to fully swell the resin, and then adding a sulfonating agent to incorporate sulfonic acid groups into the polystyrene-divinylbenzene nanosphere structure resin;

[0044] (3) After filtration, washing and high-temperature drying, a resin-type catalyst with a nanosphere structure is obtained.

[0045] Specifically, the present invention provides a method for preparing a resin-type catalyst having a nanosphere structure, which may include the following steps:

[0046] (1) fully mixing styrene monomer, divinylbenzene, stabilizer, initiator, pore-forming agent and deionized water, stirring (mechanical stirring intensity of 150 rpm-500 rpm, stirring time of 12-48 h) at a constant temperature (50-90° C.) and inert gas (at least one of nitrogen or helium) atmosphere to obtain a polystyrene-divinylbenzene nanosphere structure resin;

[0047] (2) drying the polystyrene-divinylbenzene nanosphere structure resin (drying temperature is 90-140° C., drying time is 6-24 h), adding the dried polystyrene-divinylbenzene nanosphere structure resin to an organic solvent to fully swell it (swelling time is 1-5 h), and then adding a sulfonation reagent to incorporate sulfonic acid groups into the polystyrene-divinylbenzene nanosphere structure resin (sulfonation reaction temperature is 70-130° C., sulfonation time is 1-5 h);

[0048] (3) After filtration, washing and high-temperature drying, a resin-type catalyst with a nanosphere structure is obtained.

[0049] In some embodiments of the present application, the amount of divinylbenzene added in step (1) is 10%-30% of the amount of styrene added, calculated by added volume. For example, in step (1), the volume of divinylbenzene added can be 10%, 15%, 20%, 25%, 30% of the volume of styrene added, or a value between any two of the above volume ratios.

[0050] In some embodiments of the present application, in step (2), the sulfonation reagent includes at least one of concentrated sulfuric acid and chlorosulfonic acid, wherein the mass percentage of sulfuric acid in the concentrated sulfuric acid is greater than or equal to 98%.

[0051] In some embodiments of the present application, in step (1), the stabilizer includes polyvinyl pyrrolidone, the initiator includes potassium persulfate, and the pore-forming agent includes at least one of toluene and n-heptane; in step (2), the organic solvent includes at least one of n-hexane, ethylene dichloride, acetone, dimethylformamide and toluene.

[0052] In a third aspect, the present application provides an application of a resin-type catalyst having a nanosphere structure in a Beckmann liquid phase rearrangement reaction. The resin-type catalyst having a nanosphere structure provided in the present application is applied to the Beckmann liquid phase rearrangement reaction, which can avoid the shortcomings of the conventional process of using oleum as a catalyst for the Beckmann liquid phase rearrangement reaction to produce caprolactam, and at the same time provides a simple and efficient method for producing caprolactam.

[0053] In a fourth aspect, an embodiment of the present application provides a method for preparing caprolactam, comprising the following steps: using cyclohexanone oxime as a reaction raw material and dimethyl sulfoxide as a reaction solvent, performing a Beckmann reaction under the catalytic action of a resin-type catalyst with a nanosphere structure to obtain caprolactam.

[0054] In some embodiments of the present application, the reaction temperature is 130-150° C. After a large number of experiments, it was found that in the process of preparing caprolactam by Beckmann reaction, the reaction temperature needs to be controlled within an appropriate range to achieve excellent raw material conversion rate and product selectivity.

[0055] In some embodiments of the present application, the amount of the resin catalyst with a nanosphere structure added is 37.5%-75% of cyclohexanone oxime by mass percentage. After a large number of experiments, it was found that in the process of preparing caprolactam by Beckmann reaction, the amount of the resin catalyst with a nanosphere structure added directly affects the raw material conversion rate and product selectivity. The amount of the resin catalyst with a nanosphere structure added is controlled within the range of 37.5%-75% of the mass of cyclohexanone oxime, which can make the reaction show excellent raw material conversion rate and product selectivity.

[0056] The following are specific preparation examples involved in the above content of the present disclosure. It should be clear that the following examples are only for illustrating the resin-type catalyst with a nanosphere structure disclosed above and its preparation method and application, and the specific implementation methods and parameters used therein are only one or several methods in accordance with the many processes and methods described above. Those skilled in the art can use other parameters according to the content introduced in this specification to prepare a resin-type catalyst with a nanosphere structure according to the above method without deviating from the core spirit disclosed in the application.

[0057] For ease of explanation, SP(St-DVB)-X is used in the following examples and comparative examples to represent the resin-type catalyst with nanosphere structure prepared with different divinylbenzene addition amounts. Wherein, S represents sulfonic acid functionalization, P(St-DVB) represents copolymerization of styrene and divinylbenzene, and X represents the volume ratio of divinylbenzene to styrene when synthesizing the resin-type catalyst with nanosphere structure.

[0058] The calculation formulas for the cyclohexanone oxime conversion rate and caprolactam selectivity involved in Test Examples 1 to 4 are as follows:

[0059] Cyclohexanone oxime conversion rate (%) = (molar amount of cyclohexanone oxime reacted / molar amount of cyclohexanone oxime added) × 100%;

[0060] Caprolactam selectivity (%) = (molar amount of caprolactam produced / molar amount of cyclohexanone oxime reacted) × 100%.

[0061] Example 1-Example 6

[0062] Embodiment 1-embodiment 6 respectively provide a resin-type catalyst having a nanosphere structure, and the preparation method thereof comprises the following steps:

[0063] (1) 13 ml of styrene, different amounts of divinylbenzene, 1.1 g of polyvinyl pyrrolidone, 0.3 g of potassium persulfate and 13 ml of n-heptane were fully mixed in a nitrogen atmosphere, and the mixture was kept at 70° C. and mechanically stirred at 350 rpm for 24 h, then cooled to room temperature, filtered, washed with water, and dried at 120° C. for 12 h to obtain polystyrene-divinylbenzene nanosphere resin;

[0064] (2) 3 g of polystyrene-divinylbenzene nanosphere resin was added to 40 ml of dichloroethane and fully swelled for 1 h, then 62.5 g of concentrated sulfuric acid (GR, wt%: 98%) was added and stirred at a constant temperature of 90°C for 3 h;

[0065] (3) The obtained mixture was cooled to room temperature, and then vacuum filtered, washed with deionized water and anhydrous ethanol until the filtrate was neutral, and fully dried in an air atmosphere at 120° C. for 12 h to obtain a resin-type catalyst with a nanosphere structure.

[0066] The sources of the reagents used in Examples 1-6 are as follows:

[0067] Styrene: 99%, containing 10-15ppm 4-tert-butylcatechol stabilizer, brand S817905, purchased from Shanghai MacLean Biochemical Technology Co., Ltd., purified with 0.1M NaOH aqueous solution before use;

[0068] Divinylbenzene: 80%, isomer mixture, containing 0.1% TBC stabilizer, brand D806655, purchased from Shanghai MacLean Biochemical Technology Co., Ltd., distilled under vacuum conditions before use;

[0069] Polyvinyl pyrrolidone: average molecular weight: 58000, K29-32, brand number P816205, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0070] Potassium persulfate: purity: >99.5%, brand 82459A, purchased from Beijing Inokai Technology Co., Ltd.;

[0071] n-Heptane: purity: >99%, brand H108111, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0072] Ethylene dichloride: purity: 99.5%, brand number D807843, purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0073] Concentrated sulfuric acid: purity: 98.0%, brand number 10021608, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0074] In Examples 1 to 6, the amounts of divinylbenzene added in step (1) and the corresponding resin-type catalysts with nanosphere structures prepared in different Examples are shown in Table 1.

[0075] Table 1. Preparation of Examples 1-6

[0076] serial number Amount of divinylbenzene / ml Catalyst products Example 1 0.65 SP(St-DVB)-5 Example 2 1.3 SP(St-DVB)-10 Example 3 1.95 SP(St-DVB)-15 Example 4 2.6 SP(St-DVB)-20 Example 5 3.25 SP(St-DVB)-25 Example 6 3.9 SP(St-DVB)-30

[0077] The Fourier transform infrared spectra of the SP(St-DVB)-X catalysts prepared in Examples 2 to 6 are shown in FIG. Figure 1 As shown, 1600cm -1 and 1448cm -1 The peak at 1035 cm is the vibration of the C=C skeleton of the benzene ring. -1 The band at 1216cm belongs to CS vibration. -1 and 1161cm -1 The frequency bands at are the asymmetric and symmetric stretching signals of the sulfonic acid group O=S=O bond, respectively. These results indicate that the sulfonic acid group has been successfully introduced into the aromatic ring of the polystyrene-divinylbenzene nanosphere structured resin.

[0078] Thermogravimetric analysis (TG) diagrams of the SP(St-DVB)-X catalysts prepared in Example 2, Example 4 and Example 6 are shown in FIG. Figure 3 As shown, the mass loss observed at 200°C at first corresponds to the elimination of physically adsorbed molecular water; then, the mass loss occurring in the range of 200-400°C corresponds to the decomposition of the sulfonic acid groups; and the subsequent mass loss mainly corresponds to the collapse of the polymer backbone. The resin-type catalyst with a nanosphere structure provided in the embodiment of the present application, the sulfonic acid groups present thereon all exhibit a high thermal decomposition temperature exceeding 200°C, which exceeds the appropriate temperature range for the liquid-phase Beckmann rearrangement, indicating that the resin-type catalyst with a nanosphere structure provided in the embodiment of the present application can be applied to the liquid-phase Beckmann rearrangement reaction.

[0079] Figure 4A This is a scanning electron microscope image of the catalyst prepared in Example 1. Figure 4B This is a scanning electron microscope image of the catalyst prepared in Example 2. Figure 4C This is a scanning electron microscope image of the catalyst prepared in Example 4. Figure 4D This is a scanning electron microscope image of the catalyst prepared in Example 6. Figure 4A-4DAs shown, most of the skeleton of the SP(St-DVB)-5 catalyst is polystyrene, which is dissolved and destroyed by ethylene dichloride during the sulfonation process, forming a dense amorphous structure with a large number of particles on the surface. A smooth surface and dispersed polymer microspheres can be observed for the SP(St-DVB)-10 catalyst. With the increase of the amount of divinylbenzene added, the surface of the SP(St-DVB)-X catalyst gradually becomes rough and the spherical structure gradually deforms. Therefore, 10% divinylbenzene addition helps to stabilize the skeleton of the SP(St-DVB)-X catalyst from being destroyed, while too high a divinylbenzene addition will cause the nanosphere structure to deform, affecting the catalytic ability of the solid acid.

[0080] Figure 5 This is a transmission electron microscope image of the catalyst prepared in Example 2. Figure 5 As shown, the SP(St-DVB)-10 catalyst is dispersed microspheres with smooth surface.

[0081] The SP(St-DVB)-X catalysts prepared in Examples 1 to 6 were subjected to nitrogen adsorption and desorption tests (BET tests). The test results are shown in Table 2.

[0082] Table 2. BET test results of SP(St-DVB)-X catalysts of Examples 1-6

[0083]

[0084] As shown in Table 2, there are mesopores in the SP(St-DVB)-X catalyst, and the presence of mesopores can promote the free diffusion of reactants and products in the catalyst. The polymer pore size and the number of acid sites do not change linearly with the amount of divinylbenzene added. When the amount of divinylbenzene added is 20%, the pore size and the number of acid sites reach the maximum value, which are 29.01nm and 4.46mmol / g, respectively. The amount of divinylbenzene added has an important influence on the microstructure and the number of acid sites of the synthesized solid acid catalyst. When the amount of divinylbenzene added reaches 20%, it helps to form a larger pore size and introduce a large number of sulfonic acid groups into the solid acid.

[0085] Test Example 1

[0086] In this test example, the SP(St-DVB)-X catalyst prepared in Example 1 to Example 6 was used in a Beckmann liquid phase rearrangement reaction, with cyclohexanone oxime as a reaction raw material and dimethyl sulfoxide as a reaction solvent. The reaction was carried out under the catalytic action of the SP(St-DVB)-X catalyst to obtain a reaction product, caprolactam.

[0087] Specifically, the method for preparing caprolactam by using Beckmann reaction comprises the following steps: adding 2g of cyclohexanone oxime and 20ml of dimethyl sulfoxide into a 50ml autoclave, then adding 1g of SP(St-DVB)-X catalyst, introducing nitrogen to purge and replace the original gas in the autoclave three times, finally maintaining the reaction pressure in the autoclave at 0.5MPa, setting the reaction temperature to 130°C, reacting for 1h, cooling the autoclave and collecting the upper liquid phase reaction product, and quantitatively analyzing the product composition by gas chromatography after sufficient centrifugation. The results are shown in Table 3.

[0088] As a control, this test example also uses a commercial strong acid cation exchange resin catalyst (Amberlyst 15) in the Beckmann liquid phase rearrangement reaction, including the following steps: 2g of cyclohexanone oxime and 20ml of dimethyl sulfoxide are added to a 50ml autoclave, and then 1g of Amberlyst 15 is added, nitrogen is introduced to purge and replace the original gas in the autoclave three times, and finally the reaction pressure in the autoclave is maintained at 0.5MPa, the reaction temperature is set to 130°C, and after reacting for 1h, the autoclave is cooled and the upper liquid phase reaction product is collected, and the product composition is quantitatively analyzed by gas chromatography after sufficient centrifugation. The results are shown in Table 3.

[0089] Table 3. Reaction results of test example 1

[0090]

[0091] It can be seen from Table 3 that, compared with Comparative Example 1, the catalytic performance of the SP(St-DVB)-X catalyst prepared by Examples 1-6 is better than that of the commercial strong acid cation exchange resin catalyst (Amberlyst 15).

[0092] Test Example 2

[0093] This test example uses the SP (St-DVB) -10 catalyst prepared in Example 2 for the Beckmann liquid phase rearrangement reaction to investigate the effects of different catalyst dosages on the reaction. Specifically, the method for preparing caprolactam using the Beckmann reaction comprises the following steps: adding 2 g of cyclohexanone oxime and 20 ml of dimethyl sulfoxide to a 50 ml autoclave, then adding different amounts of SP (St-DVB) -10 catalyst, passing nitrogen to purge and replace the original gas in the autoclave three times, finally maintaining the reaction pressure in the autoclave at 0.5 MPa, setting the reaction temperature to 130 ° C, reacting for 1 hour, cooling the autoclave and collecting the upper liquid phase reaction product, and quantitatively analyzing the product composition by gas chromatography after sufficient centrifugation, and the results are shown in Table 4.

[0094] Table 4. Reaction results of test example 2

[0095]

[0096] It can be seen from Table 4 that as the amount of catalyst increases, the cyclohexanone oxime conversion rate increases accordingly, but the caprolactam selectivity fluctuates, and as the amount of catalyst increases from 1 g to 1.5 g, the caprolactam selectivity begins to decrease.

[0097] Test Example 3

[0098] In this test example, the SP (St-DVB) -10 catalyst prepared in Example 2 is used in the Beckmann liquid phase rearrangement reaction to investigate the effect of different reaction temperatures on the product in the Beckmann liquid phase rearrangement reaction. Specifically, the method for preparing caprolactam using the Beckmann reaction comprises the following steps: adding 2g of cyclohexanone oxime and 20ml of dimethyl sulfoxide to a 50ml autoclave, then adding 1g of SP (St-DVB) -10 catalyst, passing nitrogen to purge and replace the original gas in the autoclave three times, and finally maintaining the reaction pressure in the autoclave at 0.5MPa, reacting at different reaction temperatures for 1h, cooling the autoclave and collecting the upper liquid phase reaction product, and quantitatively analyzing the product composition by gas chromatography after sufficient centrifugation, and the results are shown in Table 5.

[0099] Table 5. Reaction results of test example 3

[0100]

[0101] It can be seen from Table 5 that as the reaction temperature gradually increases, the cyclohexanone oxime conversion rate is significantly improved, but the caprolactam selectivity first increases and then decreases. At a reaction temperature of 130°C, a higher cyclohexanone oxime conversion rate and a higher caprolactam selectivity can be achieved.

[0102] Test Example 4

[0103] This test example uses the SP (St-DVB) -10 catalyst prepared in Example 2 for the Beckmann liquid phase rearrangement reaction to investigate the effects of different reaction times on the product in the Beckmann liquid phase rearrangement reaction. Specifically, the method for preparing caprolactam using the Beckmann reaction comprises the following steps: adding 2g of cyclohexanone oxime and 20ml of dimethyl sulfoxide to a 50ml autoclave, then adding 1g of SP (St-DVB) -10 catalyst, introducing nitrogen to purge and replace the original gas in the autoclave three times, finally maintaining the reaction pressure in the autoclave at 0.5MPa, setting the reaction temperature to 130°C, and after reacting for different times, cooling the autoclave and collecting the upper liquid phase reaction product, and quantitatively analyzing the product composition by gas chromatography after sufficient centrifugation, and the results are shown in Table 6.

[0104] Table 6. Reaction results of test example 4

[0105]

[0106] It can be seen from Table 6 that as the reaction time gradually increases, the cyclohexanone oxime conversion rate increases, but the caprolactam selectivity decreases. In practical applications, the reaction time can be adjusted as appropriate according to the actual situation to achieve a higher cyclohexanone oxime conversion rate and a higher caprolactam selectivity.

[0107] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0108] The above-described embodiments only express several embodiments of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present invention are all within the protection scope of the claims attached to the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims, and the description and drawings may be used to interpret the contents of the claims.

Claims

1. A resin-type catalyst having a nanosphere structure, characterized in that: The invention comprises a polystyrene-divinylbenzene nanosphere structure resin and a sulfonic acid group, wherein the sulfonic acid group is located on the benzene ring of the polystyrene-divinylbenzene nanosphere structure resin.

2. The resin-type catalyst having a nanosphere structure as claimed in claim 1, characterized in that: The resin-type catalyst has a mesoporous structure, and the specific surface area of ​​the resin-type catalyst is 9-13 m 2 ·g -1 , pore volume is 0.01-0.02cm 3 ·g -1 .

3. The resin-type catalyst having a nanosphere structure as claimed in claim 1, characterized in that: The thermal decomposition temperature of the resin-type catalyst with a nanosphere structure is greater than 200°C.

4. A method for preparing a resin-type catalyst having a nanosphere structure, characterized in that: The following steps are involved: (1) fully mixing styrene monomer, divinylbenzene, a stabilizer, an initiator, a pore-forming agent and deionized water, and stirring at a constant temperature and in an inert gas atmosphere to obtain a polystyrene-divinylbenzene nanosphere structure resin; (2) drying the polystyrene-divinylbenzene nanosphere structure resin, adding the dried polystyrene-divinylbenzene nanosphere structure resin into an organic solvent to fully swell it, and then adding a sulfonating agent to incorporate sulfonic acid groups into the polystyrene-divinylbenzene nanosphere structure resin; (3) After filtration, washing and high-temperature drying, the resin-type catalyst with the nanosphere structure is obtained.

5. The method for preparing the resin-type catalyst having a nanosphere structure according to claim 4, characterized in that: Calculated by added volume, the amount of divinylbenzene added in step (1) is 10%-30% of the amount of styrene added.

6. The method for preparing a resin-type catalyst having a nanosphere structure according to claim 4, characterized in that: In step (2), the sulfonation reagent includes at least one of concentrated sulfuric acid and chlorosulfonic acid.

7. The method for preparing a resin-type catalyst having a nanosphere structure according to claim 4, characterized in that: In step (1), the stabilizer includes polyvinyl pyrrolidone, the initiator includes potassium persulfate, and the pore-forming agent includes at least one of toluene and n-heptane; in step (2), the organic solvent includes at least one of n-hexane, ethylene dichloride, acetone, dimethylformamide and toluene.

8. Use of the resin-type catalyst having a nanosphere structure as described in any one of claims 1 to 3 in a Beckmann liquid phase rearrangement reaction.

9. A method for preparing caprolactam, characterized in that: The following steps are involved: Cyclohexanone oxime is used as a reaction raw material, dimethyl sulfoxide is used as a reaction solvent, and Beckmann reaction is carried out under the catalytic action of a resin-type catalyst with a nanosphere structure to obtain caprolactam.

10. The method for preparing caprolactam according to claim 9, characterized in that: The reaction temperature is 130-150° C.; in terms of mass percentage, the added amount of the resin-type catalyst with a nanosphere structure is 37.5%-75% of the cyclohexanone oxime.

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