A catalyst for liquid-phase Beckmann rearrangement to produce caprolactam, and its preparation method and application

Abstract

The present invention provides a catalyst for the liquid-phase Beckmann rearrangement of caprolactam, as well as its preparation method and application. The catalyst belongs to the technical field of chemical catalysts and is used to address the technical problem of low conversion rate and selectivity when using a strong acid polymer resin as a catalyst to prepare caprolactam. The preparation method of the catalyst of the present invention comprises the following steps: (1) mixing an aluminum halide, a perfluorosulfonic acid resin, and a solvent I, and reacting to produce an active component A; (2) mixing a fluoride, the active component A, and a solvent II to produce an impregnation solution; and (3) impregnating a carbon support in the impregnation solution and drying to produce a catalyst. The catalyst is used to catalyze the Beckmann rearrangement reaction of cyclohexanone oxime to produce caprolactam. In the Beckmann rearrangement reaction of cyclohexanone oxime, the catalyst provided by the present invention achieves a maximum cyclohexanone oxime conversion rate of 100% and a maximum caprolactam selectivity of 99.5%.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical catalysts, and in particular relates to a catalyst for preparing caprolactam by liquid-phase Beckmann rearrangement, and a preparation method and application thereof. Background Art

[0002] Caprolactam is an important organic chemical raw material. Traditionally, its production has been catalyzed by concentrated sulfuric acid or fuming acid. This process has drawbacks, including equipment corrosion, difficulty in product separation, and the formation of large amounts of low-value-added ammonium sulfate. Developing environmentally friendly, recyclable catalysts for the liquid-phase Beckmann rearrangement, which exhibit mild reaction conditions, remains a challenge.

[0003] Resin is a functional polymer material with low cost, plasticity, and structural pore properties. It is widely used in many fields such as heterogeneous catalysis. You Kuiyi et al. (You Kuiyi, Zeng Zhen, Wang Liangjie, et al. Liquid-phase Beckmann rearrangement of cyclohexanone oxime to caprolactam catalyzed by D-72 sulfonic acid resin [J]. Molecular Catalysis, 2010, 24(4): 327-332.) used D-72 solid sulfonic acid resin as a catalyst for the liquid-phase rearrangement of cyclohexanone oxime. The cyclohexanone oxime conversion rate was 100%, the caprolactam selectivity was 86.2%, and the main by-product was cyclohexanone. Zhou Yun et al. (Zhou Yun, Satmon John, Chen Hengquan, et al. Amberlyst 36 sulfonic acid resin catalyzes the liquid phase rearrangement of cyclohexanone oxime to caprolactam [J]. Synthetic Fiber Industry, 2016, 38(3): 11-15.) found that Amberlyst 36 sulfonic acid resin has good catalytic performance for the liquid phase rearrangement reaction of cyclohexanone oxime (cyclohexanone oxime conversion rate is 93.93%, caprolactam selectivity is 87.54%), but the catalyst regeneration performance is poor. Liu Xianxiang et al. (Liu Xianxiang, Mao Liqiu, Xu Qiong, et al. Sulfonic acid resin Amberlyst 70 catalyzes the liquid-phase rearrangement of cyclohexanone oxime to produce caprolactam [J]. Fine Petrochemicals, 2011, 28(4): 1-4.) found that Amberlyst 70 sulfonic acid resin has good catalytic performance in catalyzing the liquid-phase rearrangement reaction of cyclohexanone oxime (cyclohexanone conversion rate is 99.4%, caprolactam selectivity is 90.2%), is non-corrosive to equipment, and is easy to separate. Li et al. (Li DF, Mao D, Li J, et al. Insitu functionalized sulfonic copolymer toward recyclable heterogeneous catalyst for efficient Beckmann rearrangement of cyclohexanoneoxime [J]. Applied Catalysis A: General, 2016, 510:125-133.) synthesized an H-PDVB-SO3H catalyst in situ and used it to catalyze the preparation of caprolactam from cyclohexanone oxime. The catalytic reaction achieved 100% cyclohexanone oxime conversion and 75% caprolactam selectivity. In summary, polymer resins exhibit excellent catalytic performance in the cyclohexanone oxime rearrangement reaction. Polymer resins also offer advantages such as low synthesis cost, environmental friendliness, and non-corrosiveness. Therefore, polymer resin catalysts have the potential to replace concentrated sulfuric acid industrial catalysts. However, current catalysts using strong acid polymer resins suffer from low cyclohexanone oxime conversion and caprolactam selectivity, and achieving a balanced balance is difficult. Summary of the Invention

[0004] To address the technical problem of low conversion rate and selectivity when strong acid polymer resin is used as a catalyst to prepare caprolactam, the present invention provides a catalyst for preparing caprolactam via liquid-phase Beckmann rearrangement, as well as a preparation method and application thereof. The maximum cyclohexanone oxime conversion rate is 100%, and the maximum caprolactam selectivity is 99.5%.

[0005] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A method for preparing a catalyst for preparing caprolactam by liquid-phase Beckmann rearrangement comprises the following steps:

[0007] (1) Under certain reaction conditions, aluminum halide, perfluorosulfonic acid resin, and solvent are weighed and placed in a reactor to react to prepare active component A;

[0008] (2) Under certain conditions, the fluoride, active component A and solvent are stirred to prepare an impregnation solution;

[0009] (3) The impregnation solution obtained in step (2) is impregnated with the carbon support and dried to obtain a catalyst.

[0010] In step (1), aluminum halide, perfluorosulfonic acid resin, and solvent are placed in a reactor for reaction to prepare active component A. The stirring temperature is 50-100° C., the stirring speed is 200-500 r / min, and the stirring time is 5-30 min. The mass ratio of aluminum halide to solvent is (1-4):6, and the mass ratio of perfluorosulfonic acid resin to solvent is (1-4):6.

[0011] The aluminum halide is one of aluminum trichloride, aluminum tribromide, aluminum trifluoride and aluminum triiodide.

[0012] The solvent is one of methanol, ethanol, acetone, ether and dimethyl sulfoxide.

[0013] In step (2), the fluoride, active component A, and solvent are mixed in a beaker to prepare an impregnation solution. The stirring temperature is 20-40°C, the stirring speed is 200-500 r / min, and the stirring time is 5-60 min. The mass ratio of fluoride to solvent is (1-3):7, and the mass ratio of active component to solvent is (1-3):7.

[0014] The fluoride is one of fluorosulfonic acid, perfluoroheptylsulfonic acid, perfluorohexylsulfonic acid, fluorophosphoric acid, hexafluorophosphoric acid, decafluorotriphenylphosphine, phosphorus fluoride, and (pentafluorophenyl)diphenylphosphine.

[0015] The impregnation solution obtained in step (2) is impregnated with a carbon support and then dried to produce a catalyst. The stirring temperature is 20-30°C, the stirring speed is 200-500 r / min, and the stirring time is 5-60 min. The mass ratio of the impregnation solution to the carbon support is (1-8):2. The drying temperature is 100-120°C and the drying time is 2-24 h.

[0016] The carbon carrier is one of fruit shell activated carbon, coal-based activated carbon, coconut shell activated carbon, fruit shell activated carbon, wood activated carbon, and petroleum-based activated carbon.

[0017] The catalyst is used in a liquid-phase Beckmann rearrangement reaction to prepare caprolactam, characterized in that caprolactam is synthesized using cyclohexanone oxime as raw materials under the catalytic action of a superacid catalyst, the cyclohexanone oxime conversion rate reaches 100%, and the caprolactam selectivity reaches 99.5%.

[0018] Cyclohexanone oxime and a catalyst are added to a catalytic reactor, heated to 80-140° C., the reaction pressure is 0.1-1.0 KPa, and the reaction time is 1-60 min; wherein the mass ratio of the catalyst to the cyclohexanone oxime is (1-50):50.

[0019] Beneficial effects of the present invention.

[0020] The catalyst prepared by the present invention has a cyclohexanone oxime conversion rate of more than 99%, and can reach up to 100%; the caprolactam selectivity can also reach more than 99%, and can reach up to 99.5%, achieving a simultaneous improvement in conversion rate and selectivity, and showing high catalytic activity. This is because the catalyst of the present invention undergoes a condensation reaction with the sulfonic acid groups on the surface of the perfluorosulfonic acid resin after removing hydrogen halide during the preparation process, and the aluminum halide reacts with the sulfonic acid groups on the surface of the perfluorosulfonic acid resin to achieve the grafting of aluminum atoms on the surface of the perfluorosulfonic acid resin ( Figure 1 ), increasing surface acidic sites (i.e., active sites) and enhancing catalyst activity. Fluorine and sulfur / phosphorus atoms can effectively increase the acidity of the catalyst, further enhancing its activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is the reaction principle diagram of aluminum atoms grafted onto the surface of perfluorosulfonic acid resin. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0024] Example 1

[0025] The preparation method of the catalyst of this embodiment is as follows:

[0026] (1) Under certain reaction conditions (reaction temperature of 60°C, stirring speed of 500 r / min, stirring time of 15 min), aluminum trifluoride (20 g), perfluorosulfonic acid resin (10 g), and methanol solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0027] (2) Under certain conditions (stirring temperature of 20°C, stirring speed of 200 r / min, stirring time of 5 min), 10 g of fluorosulfonic acid, 15 g of active component A, and 70 g of ethanol were stirred to prepare an impregnation solution;

[0028] (3) 80 g of the impregnation solution obtained in step (2) was impregnated with 20 g of fruit shell activated carbon and dried to obtain catalyst 1 (stirring temperature was 20° C., stirring speed was 200 r / min, stirring time was 60 min, drying temperature was 100° C., and drying time was 2 h).

[0029] (4) Cyclohexanone oxime and catalyst 1 were added to a catalytic reactor, heated to 140° C., and reacted for 30 minutes; wherein the mass ratio of catalyst to cyclohexanone oxime was 1:1. The cyclohexanone oxime conversion was 100%, and the caprolactam selectivity was 99.2%.

[0030] The active component A was washed with a large amount of methanol and filtered through a Buchner funnel to obtain a modified perfluorosulfonic acid resin. The Al atom content on the catalyst surface was determined by ICP technology to be 3.12 wt%, indicating that the Al atoms were successfully grafted onto the perfluorosulfonic acid resin.

[0031] Example 2

[0032] The preparation method of the catalyst of this embodiment is as follows:

[0033] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), aluminum tribromide (20 g), perfluorosulfonic acid resin (10 g), and ethanol solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0034] (2) Under certain conditions (stirring temperature of 40°C, stirring speed of 200 r / min, stirring time of 5 min), 10 g of perfluorohexane sulfonic acid, 15 g of active component A and 70 g of ethanol were stirred to prepare an impregnation solution;

[0035] (3) 80 g of the impregnation solution obtained in step (2) was impregnated with 20 g of coal-based activated carbon and dried to obtain catalyst 2 (stirring temperature was 30° C., stirring speed was 200 r / min, stirring time was 60 min, drying temperature was 120° C., and drying time was 2 h).

[0036] (4) Cyclohexanone oxime and catalyst 2 were added to a catalytic reactor, heated to 130° C., and reacted for 60 min; wherein the mass ratio of catalyst to cyclohexanone oxime was 1:1. The cyclohexanone oxime conversion was 99.3%, and the caprolactam selectivity was 99.5%.

[0037] Example 3

[0038] The preparation method of the catalyst of this embodiment is as follows:

[0039] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), aluminum triiodide (20 g), perfluorosulfonic acid resin (10 g), and ethanol solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0040] (2) Under certain conditions (stirring temperature of 40°C, stirring speed of 200 r / min, stirring time of 5 min), 20 g of hexafluorophosphoric acid, 10 g of active component A, and 70 g of ethanol were stirred to prepare an impregnation solution;

[0041] (3) 80 g of the impregnation solution obtained in step (2) was impregnated with 20 g of coconut shell activated carbon and dried to obtain catalyst 3 (stirring temperature was 30° C., stirring speed was 200 r / min, stirring time was 60 min, drying temperature was 120° C., and drying time was 2 h).

[0042] (4) Cyclohexanone oxime and catalyst 3 were added to a catalytic reactor, heated to 120° C., and reacted for 60 min; wherein the mass ratio of catalyst to cyclohexanone oxime was 1:1. The cyclohexanone oxime conversion was 99.7%, and the caprolactam selectivity was 99.0%.

[0043] Example 4

[0044] The preparation method of the catalyst of this embodiment is as follows:

[0045] (1) Under certain reaction conditions (reaction temperature of 50°C, stirring speed of 300 r / min, stirring time of 5 min), aluminum tribromide (40 g), perfluorosulfonic acid resin (10 g), and ether solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0046] (2) Under certain conditions (stirring temperature of 30°C, stirring speed of 500 r / min, stirring time of 60 min), 15 g of perfluorohexanesulfonic acid, 15 g of active component A and 70 g of ethanol were stirred to prepare an impregnation solution;

[0047] (3) 10 g of the impregnation solution obtained in step (2) was impregnated with 20 g of coal-based activated carbon and dried to obtain catalyst 4 (stirring temperature was 25°C, stirring speed was 300 r / min, stirring time was 50 min, drying temperature was 110°C, and drying time was 12 h).

[0048] (4) Cyclohexanone oxime and catalyst 4 were added to a catalytic reactor, heated to 130° C., and reacted for 60 minutes; wherein the mass ratio of catalyst to cyclohexanone oxime was 1:1. The cyclohexanone oxime conversion was 99.2%, and the caprolactam selectivity was 99.3%.

[0049] Example 5

[0050] The preparation method of the catalyst of this embodiment is as follows:

[0051] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), aluminum trichloride (15 g), perfluorosulfonic acid resin (15 g), and ethanol solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0052] (2) Under certain conditions (stirring temperature of 40°C, stirring speed of 200 r / min, stirring time of 5 min), 15 g of decafluorotriphenylphosphine, 15 g of active component A and 70 g of ethanol were stirred to prepare an impregnation solution;

[0053] (3) 80 g of the impregnation solution obtained in step (2) was impregnated with 20 g of coal-based activated carbon and dried to obtain catalyst 5 (stirring temperature was 30° C., stirring speed was 500 r / min, stirring time was 60 min, drying temperature was 120° C., and drying time was 2 h).

[0054] (4) Cyclohexanone oxime and catalyst 5 were added to a catalytic reactor, heated to 140° C., and reacted for 60 minutes; wherein the mass ratio of catalyst to cyclohexanone oxime was 1:1. The cyclohexanone oxime conversion was 99.1%, and the caprolactam selectivity was 99.1%.

[0055] Example 6

[0056] The preparation method of the catalyst of this embodiment is as follows:

[0057] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), aluminum trifluoride (30 g), perfluorosulfonic acid resin (10 g), and ethanol solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0058] (2) Under certain conditions (stirring temperature of 40°C, stirring speed of 200 r / min, stirring time of 5 min), 15 g of fluorophosphoric acid, 15 g of active component A, and 70 g of ethanol were stirred to prepare an impregnation solution;

[0059] (3) 80 g of the impregnation solution obtained in step (2) was impregnated with 20 g of coal-based activated carbon and dried to obtain catalyst 6 (stirring temperature was 30° C., stirring speed was 500 r / min, stirring time was 60 min, drying temperature was 120° C., and drying time was 2 h).

[0060] (4) Cyclohexanone oxime and catalyst 6 were added to a catalytic reactor, heated to 140° C., and reacted for 60 minutes; wherein the mass ratio of catalyst to cyclohexanone oxime was 1:1. The cyclohexanone oxime conversion was 99.0%, and the caprolactam selectivity was 99.3%.

[0061] Example 7

[0062] The preparation method of the catalyst of this embodiment is as follows:

[0063] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), aluminum trifluoride (10 g), perfluorosulfonic acid resin (30 g), and dimethyl sulfoxide solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0064] (2) Under certain conditions (stirring temperature of 40°C, stirring speed of 200 r / min, stirring time of 5 min), 30 g of hexafluorophosphoric acid, 30 g of active component A, and 70 g of dimethyl sulfoxide were stirred to prepare an impregnation solution;

[0065] (3) 80 g of the impregnation solution obtained in step (2) was impregnated with 20 g of coal-based activated carbon and dried to obtain catalyst 7 (stirring temperature was 30° C., stirring speed was 500 r / min, stirring time was 60 min, drying temperature was 120° C., and drying time was 24 h).

[0066] (4) Cyclohexanone oxime and catalyst 7 were added to a catalytic reactor, heated to 80°C, and reacted for 60 minutes; the mass ratio of catalyst to cyclohexanone oxime was 1:2. The cyclohexanone oxime conversion was 99.3%, and the caprolactam selectivity was 99.2%.

[0067] Example 8

[0068] The preparation method of the catalyst of this embodiment is as follows:

[0069] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), aluminum trichloride (15 g), perfluorosulfonic acid resin (25 g), and ethanol solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0070] (2) Under certain conditions (stirring temperature of 40°C, stirring speed of 200 r / min, stirring time of 5 min), 30 g of decafluorotriphenylphosphine, 15 g of active component A and 70 g of ethanol were stirred to prepare an impregnation solution;

[0071] (3) 80 g of the impregnation solution obtained in step (2) was impregnated with 20 g of wood activated carbon and dried to obtain catalyst 8 (stirring temperature was 30° C., stirring speed was 500 r / min, stirring time was 5 min, drying temperature was 120° C., and drying time was 24 h).

[0072] (4) Cyclohexanone oxime and catalyst 8 were added to a catalytic reactor, heated to 140° C., and reacted for 60 min; wherein the mass ratio of catalyst to cyclohexanone oxime was 1:1. The cyclohexanone oxime conversion was 99.1%, and the caprolactam selectivity was 99.1%.

[0073] Example 9

[0074] The preparation method of the catalyst of this embodiment is as follows:

[0075] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), aluminum trifluoride (30 g), perfluorosulfonic acid resin (15 g), and ethanol solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0076] (2) Under certain conditions (stirring temperature of 40°C, stirring speed of 200 r / min, stirring time of 5 min), 30 g of phosphorus fluoride, 10 g of active component A, and 70 g of ethanol were stirred to prepare an impregnation solution;

[0077] (3) 80 g of the impregnation solution obtained in step (2) was impregnated with 20 g of coal-based activated carbon and dried to obtain catalyst 9 (stirring temperature was 30° C., stirring speed was 500 r / min, stirring time was 60 min, drying temperature was 120° C., and drying time was 2 h).

[0078] (4) Cyclohexanone oxime and catalyst 9 were added to a catalytic reactor, heated to 140° C., and reacted for 60 min; wherein the mass ratio of catalyst to cyclohexanone oxime was 1:50. The cyclohexanone oxime conversion was 99.2%, and the caprolactam selectivity was 99.0%.

[0079] Example 10

[0080] The preparation method of the catalyst of this embodiment is as follows:

[0081] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), aluminum trichloride (30 g), perfluorosulfonic acid resin (30 g), and acetone solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0082] (2) Under certain conditions (stirring temperature of 40°C, stirring speed of 200 r / min, stirring time of 5 min), 30 g of perfluoroheptanesulfonic acid, 30 g of active component A and 70 g of acetone were stirred to prepare an impregnation solution;

[0083] (3) 80 g of the impregnation solution obtained in step (2) was impregnated with 20 g of coal-based activated carbon and dried to obtain catalyst 10 (stirring temperature was 30° C., stirring speed was 200 r / min, stirring time was 60 min, drying temperature was 120° C., and drying time was 2 h).

[0084] (4) Cyclohexanone oxime and catalyst 10 were added to a catalytic reactor, heated to 140° C., and reacted for 60 minutes; wherein the mass ratio of catalyst to cyclohexanone oxime was 1:10. The cyclohexanone oxime conversion was 99.5%, and the caprolactam selectivity was 99.1%.

[0085] Comparative Example 1

[0086] The preparation method of the catalyst of this embodiment is as follows:

[0087] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), first, perfluorosulfonic acid resin (30 g) and acetone solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0088] (2) Under certain conditions (stirring temperature of 40°C, stirring speed of 200 r / min, stirring time of 5 min), 30 g of perfluoroheptanesulfonic acid, 30 g of active component A and 70 g of acetone were stirred to prepare an impregnation solution;

[0089] (3) 80 g of the impregnation solution obtained in step (2) was impregnated with 20 g of coal-based activated carbon and dried to obtain comparative catalyst 1 (stirring temperature was 30°C, stirring speed was 200 r / min, stirring time was 60 min, drying temperature was 120°C, and drying time was 2 h).

[0090] (4) Cyclohexanone oxime and comparative catalyst 1 were added to a catalytic reactor, heated to 140°C, and reacted for 60 minutes; the mass ratio of catalyst to cyclohexanone oxime was 1:10. The cyclohexanone oxime conversion was 88.4%, and the caprolactam selectivity was 95.7%.

[0091] Comparative Example 2

[0092] The preparation method of the catalyst of this embodiment is as follows:

[0093] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), perfluorosulfonic acid resin (30 g) and acetone solvent (60 g) were weighed and placed in a reactor for reaction to prepare comparative catalyst 2;

[0094] (2) Cyclohexanone oxime and comparative catalyst 2 were added to a catalytic reactor, heated to 140°C, and reacted for 60 minutes; the mass ratio of catalyst to cyclohexanone oxime was 1:10. The cyclohexanone oxime conversion was 67.2%, and the caprolactam selectivity was 90.9%.

[0095] Comparative Example 3

[0096] The preparation method of the catalyst of this embodiment is as follows:

[0097] (1) Under certain reaction conditions (reaction temperature of 100°C, stirring speed of 200 r / min, stirring time of 30 min), aluminum trichloride (30 g), perfluorosulfonic acid resin (30 g), and acetone solvent (60 g) were weighed and placed in a reactor for reaction to prepare active component A;

[0098] (2) The A obtained in step (1) was impregnated with 20 g of coal-based activated carbon and dried to obtain comparative catalyst 2 (stirring temperature was 30°C, stirring speed was 200 r / min, stirring time was 60 min, drying temperature was 120°C, and drying time was 2 h).

[0099] (3) Cyclohexanone oxime and comparative catalyst 2 were added to a catalytic reactor, heated to 140°C, and reacted for 60 minutes; the mass ratio of catalyst to cyclohexanone oxime was 1:10. The cyclohexanone oxime conversion was 54.3%, and the caprolactam selectivity was 98.7%.

[0100] Table 1 Catalytic performance of catalysts prepared in Examples 1-13

[0101] Catalyst name Conversion rate (%) Selectivity (%) Catalyst 1 100 99.2 Catalyst 2 99.3 99.5 Catalyst 3 99.7 99.0 Catalyst 4 99.2 99.3 Catalyst 5 99.1 99.1 Catalyst 6 99.0 99.3 Catalyst 7 99.3 99.2 Catalyst 8 99.4 99.2 Catalyst 9 99.2 99.0 Catalyst 10 99.5 99.1 Comparative Catalyst 1 88.4 95.7 Comparative Catalyst 2 67.2 90.9 Comparative Catalyst 3 54.3 98.7

[0102] As shown in Table 1, the catalyst prepared by the present invention has a cyclohexanone oxime conversion rate of more than 99%, up to 100%; the caprolactam selectivity can also reach more than 99%, up to 99.5%, achieving a simultaneous improvement in conversion rate and selectivity, and showing a higher catalytic activity. As shown in Example 10 and Comparative Examples 1-3, the catalytic activity of using perfluorosulfonic acid resin alone, active component A, or as a carbon carrier loaded with active component A as a catalyst (without fluorine doping) is lower than that of the present invention, further demonstrating that aluminum atoms are grafted onto the surface of the perfluorosulfonic acid resin, and the acidity of the catalyst is further enhanced by fluorine and sulfur / phosphorus atoms. By utilizing the synergistic effect of the two, the activity of the strong acid polymer resin catalyst can be effectively improved.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst for preparing caprolactam by liquid-phase Beckmann rearrangement, characterized in that: The following steps are involved: (1) Aluminum halide, perfluorosulfonic acid resin and solvent I are mixed and reacted to obtain active component A; (2) mixing the fluoride, active component A and solvent II to prepare an impregnation solution; (3) Impregnating the carbon support in an impregnation solution and drying the carbon support to obtain a catalyst; The mass ratio of the aluminum halide, perfluorosulfonic acid resin and solvent I is (1-4): (1-4): 6; The reaction temperature in step (1) is 50-100°C, the reaction time is 5-30 min, and the reaction is carried out under stirring at a stirring speed of 200-500 r / min; The fluoride is any one of fluorosulfonic acid, perfluoroheptylsulfonic acid, perfluorohexylsulfonic acid, fluorophosphoric acid, hexafluorophosphoric acid, decafluorotriphenylphosphine, phosphorus fluoride, and (pentafluorophenyl)diphenylphosphine.

2. The method for preparing a catalyst for preparing caprolactam by liquid-phase Beckmann rearrangement according to claim 1, characterized in that: The aluminum halide is any one of aluminum trichloride, aluminum tribromide, aluminum trifluoride or aluminum triiodide.

3. The method for preparing a catalyst for preparing caprolactam by liquid-phase Beckmann rearrangement according to claim 1, characterized in that: The solvent I and solvent II are any one of methanol, ethanol, acetone, ether and dimethyl sulfoxide.

4. The method for preparing a catalyst for preparing caprolactam by liquid-phase Beckmann rearrangement according to claim 1, characterized in that: The mass ratio of fluoride, active component A and solvent II is (1-3): (1-3):

7.

5. The method for preparing a catalyst for preparing caprolactam by liquid-phase Beckmann rearrangement according to claim 1, characterized in that: The mass ratio of the impregnation liquid to the carbon carrier is (1-8):2; the carbon carrier is one of wood activated carbon, coal-based activated carbon or petroleum-based activated carbon.

6. A catalyst for liquid-phase Beckmann rearrangement to caprolactam prepared by the method according to any one of claims 1 to 5.

7. Use of the catalyst according to claim 6 in the liquid phase Beckmann rearrangement reaction to produce caprolactam, characterized in that Caprolactam is synthesized using cyclohexanone oxime as raw material under the catalytic action of a catalyst.

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