A method for regenerating a silicon molecular sieve catalyst

Abstract

A regeneration method of a silicon molecular sieve catalyst. A regeneration method of a molecular sieve catalyst is provided, which comprises the following steps: (1) calcining the deactivated silicon molecular sieve; (2) mixing raw materials including an organosilicon compound, water and a template agent and performing a hydrolysis reaction to obtain a solution; (3) mixing the solution obtained in step (2) and the calcined molecular sieve obtained in step (1) to perform a first treatment, and separating to obtain a molecular sieve solid; (4) drying and calcining the molecular sieve solid obtained in step (3); and (5) mixing the calcined solid obtained in step (4) with an organic amine and a solvent, and drying and calcining to obtain the regenerated molecular sieve.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more specifically, to a method for regenerating molecular sieves and their applications. Background Technology

[0002] Caprolactam is an important intermediate in the industrial production of nylon, and the Beckmann rearrangement of cyclohexanone oxime is one of the key steps in caprolactam production. Currently, the traditional liquid-phase rearrangement process using concentrated sulfuric acid as a catalyst is mainly used industrially. Although this process has relatively mild reaction conditions and ideal conversion and selectivity, it produces a large amount of ammonium sulfate as a byproduct and easily causes equipment corrosion and environmental pollution. To overcome these drawbacks, the gas-phase Beckmann rearrangement process of cyclohexanone oxime catalyzed by solid acids such as molecular sieves has attracted attention in recent years. However, the gas-phase Beckmann rearrangement process requires high reaction temperatures, has poor catalyst stability, rapid deactivation, and relatively low catalyst selectivity.

[0003] US4061724, CN104307556, and CN1338427 all report methods for synthesizing MFI-type silica molecular sieves and their application in the synthesis of caprolactam. However, the synthesis process of high-efficiency MFI-type silica molecular sieves is lengthy and complex, with high raw material costs, leading to high catalyst preparation costs. Furthermore, the single-pass stable operating lifetime of all the aforementioned molecular sieve catalysts for cyclohexanone oxime gas-phase rearrangement is less than 4000 hours, requiring regeneration to reduce catalyst application costs in industrial applications. However, due to prolonged high-temperature reactions, the MFI molecular sieve catalysts exhibit localized "sintering," making it difficult to restore the catalyst's catalytic performance using conventional calcination regeneration processes.

[0004] Therefore, developing a regeneration technology for deactivated molecular sieve catalysts in the cyclohexanone oxime gas-phase rearrangement process is of great significance for industrialization. Summary of the Invention

[0005] The purpose of this application is to provide a method and application for regenerating deactivated silicon-based molecular sieves, in order to solve the problems in the prior art where the catalyst has decreased selectivity, poor stability, or low overall lifetime after deactivation and regeneration of molecular sieves through catalytic cyclohexanone oxime gas-phase rearrangement.

[0006] This application provides a method for regenerating a molecular sieve catalyst, the method comprising the following steps:

[0007] (1) Calcination of deactivated silicon molecules;

[0008] (2) Mix raw materials including organosilicon compounds, water, and template agents and carry out hydrolysis reaction to obtain a solution;

[0009] (3) The solution obtained in step (2) and the calcined molecular sieve obtained in step (1) are mixed and subjected to the first treatment to separate the solid molecular sieve.

[0010] (4) The molecular sieve solid obtained in step (3) is dried and calcined;

[0011] (5) The solid after calcination in step (4) is mixed with organic amine and solvent, and then dried and calcined to obtain the regenerated molecular sieve.

[0012] Another aspect of this application provides a regenerated catalyst for a gas-phase Beckmann rearrangement reaction, said regenerated catalyst being regenerated according to the method of this application.

[0013] This application also provides a method for preparing caprolactam, the method comprising the following steps:

[0014] (1) Provide cyclohexanone oxime vapor;

[0015] (2) The cyclohexanone oxime vaporized product was subjected to a gas-phase Beckmann rearrangement reaction using a catalyst to obtain caprolactam.

[0016] The catalyst is a molecular sieve catalyst obtained according to the regeneration method of this application.

[0017] The advantages of this application are:

[0018] (1) By using high-temperature calcination, crystallization treatment and organic amine modification, carbon deposits on deactivated rearranged catalysts are effectively removed, and the collapsed catalyst pore structure and high-efficiency active sites are reconstructed, solving the problem of catalyst performance degradation in conventional regeneration methods and realizing the effective regeneration of rearranged catalysts.

[0019] (2) Using this catalyst significantly improves the efficiency of the rearrangement catalyst, reduces the use of expensive fresh rearrangement catalyst, and lowers the cost of using the rearrangement catalyst.

[0020] (3) The regenerated catalyst has high selectivity and long service life, which is conducive to the industrial production of caprolactam by gas phase method. Detailed Implementation

[0021] The "range" disclosed herein is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0022] Unless otherwise specified in this application, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0023] Unless otherwise specified, all technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0024] In this application, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0025] In this application, unless otherwise specified, the terms "comprising" and "including" as used herein are open-ended or closed-ended. For example, "comprising" and "including" may mean that other components not listed may also be included, or that only the listed components may be included.

[0026] In the description of this article, it should be noted that, unless otherwise stated, "above" and "below" include the number itself, and "several" in "one or more" means two or more.

[0027] In this description, unless otherwise stated, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0028] Unless otherwise specified, percentages (%) or parts refer to weight percentages or parts relative to the composition.

[0029] Unless otherwise stated herein, the sum of the contents of the components in the composition is 100%.

[0030] Unless otherwise stated herein, the sum of the parts of each component in the composition may be 100 parts by weight.

[0031] In this document, unless otherwise stated, “combination of” means a multi-component mixture of the elements, such as two, three, four, and up to the maximum possible multi-component mixture.

[0032] Unless otherwise specified, the term "a" as used in this specification means "at least one".

[0033] In this paper, unless otherwise stated, all reactions were carried out at room temperature and pressure.

[0034] In this document, unless otherwise stated, the terms “catalyst” or “molecular sieve catalyst” or “silicon molecular catalyst” have the same meaning and refer to conventional silicon molecular sieve catalysts used to catalyze the gas-phase Beckmann rearrangement of cyclohexanone oxime, including but not limited to S-1 molecular sieve catalysts, ZSM-5 molecular sieve catalysts, etc.

[0035] This application provides a method for regenerating a molecular sieve catalyst, the method comprising the following steps:

[0036] (1) Calcination of the deactivated silicon molecular sieve;

[0037] (2) Mix raw materials including organosilicon compounds, water, and template agents and carry out hydrolysis reaction to obtain a solution;

[0038] (3) The solution obtained in step (2) and the calcined molecular sieve obtained in step (1) are mixed and subjected to the first treatment to separate the solid molecular sieve.

[0039] (4) The molecular sieve solid obtained in step (3) is dried and calcined;

[0040] (5) The solid after calcination in step (4) is mixed with organic amine and solvent, and then dried and calcined to obtain the regenerated molecular sieve.

[0041] In this application, the term "deactivated catalyst" refers to a catalyst that has been used in the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime. Typically, the deactivated catalyst can also be a catalyst used in the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime for a predetermined time (e.g., more than 1000 hours), or a catalyst that has lost its catalytic activity in the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, for example, whose products do not meet industrial standards (CHO conversion < 99%, CPL selectivity < 95%).

[0042] In one example of this application, the calcination process in step (1) above is conventional and can be a commonly used calcination process in the art for regenerating molecular sieve catalysts. In one example of this application, the calcination temperature is 300-1000℃ (preferably 350-800℃, more preferably 400-600℃), the calcination time is 1-72h (preferably 2-60h, more preferably 4-48h), and the oxygen volume concentration during calcination is 0.1-30% (preferably 0.5-20%, more preferably 1%-10%).

[0043] Typically, in step (1) above, the temperature can be raised to the calcination temperature using conventional methods. In a preferred embodiment of this application, the heating process can be a dual-gradient heating process. For example, the temperature is raised to 250–350°C at a heating rate of 0.1–10°C / min (preferably 0.2–8°C / min, more preferably 0.5–5°C / min), held for 0.5–48 h (preferably 1–36 h, more preferably 1–24 h), and then raised to the calcination temperature at a heating rate of 0.05–10°C / min (preferably 0.1–5°C / min, more preferably 0.2–2°C / min) for calcination. The dual-gradient heating process can achieve a better calcination effect, thereby improving the catalyst regeneration effect.

[0044] In this application, the organosilicon compound includes, but is not limited to, alkyl orthosilicates, alkyl metasilicates, or combinations thereof. The alkyl orthosilicates include C1-C20 alkyl orthosilicates. In one example of this application, the alkyl orthosilicate is selected from one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, or butyl orthosilicate. In one example of this application, the alkyl metasilicate includes C1-C20 alkyl metasilicates. In one example of this application, the alkyl metasilicate is selected from one or more of methyl orthosilicate, ethyl orthosilicate, propyl or butyl metasilicate.

[0045] In this application, the water may be deionized water, distilled water, ultrapure water, etc.

[0046] In this application, the template agent can be a commonly used template agent for preparing molecular sieve catalysts, including but not limited to organic amines, quaternary ammonium salts, metal complexes, quaternary phosphazenes, and proton sponges. In one example of this application, the template agent is selected from organic amines, quaternary ammonium salts, or combinations thereof. The organic amines include, but are not limited to, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, dibutylamine, tributylamine, ethylenediamine, ethanolamine, or combinations thereof. The quaternary ammonium salt is selected from one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium bromide, tetrapropylammonium bromide, tetraethylammonium chloride, and tetrapropylammonium chloride. This application preferably uses quaternary ammonium salt template agents to improve the performance of the regenerated catalyst.

[0047] In step (2) above, in addition to organosilicon compounds, water and template agents, the raw materials may also include commonly used additives in the art, including but not limited to pH adjusters, surfactants, protectants or combinations thereof.

[0048] In this application, the temperature of the hydrolysis reaction in step (2) above is generally 15-60℃ (preferably 20-40℃), and the time of the hydrolysis reaction is generally 1-6h (preferably 2-4h).

[0049] In this application, the amounts of the organosilicon compound, water, and template agent used in step (2) above are conventional, and those skilled in the art can reasonably determine their specific amounts. To improve the performance of the regenerated catalyst, in one example of this application, the molar ratio of the organosilicon compound, water, and template agent is controlled to be 1:10–500:0.01–10, preferably 1:20–400:0.05–5, and more preferably 1:50–250:0.1–1.

[0050] In this application, the first treatment in step (3) above can be performed using processing techniques commonly used in the art. In one example of this application, in order to obtain a better catalyst regeneration effect, the solution obtained in step (2) and the calcined molecular sieve obtained in step (1) are mixed at a mass ratio of 1-50:1, preferably 2-40:1, more preferably 3-20:1, and most preferably 4-20:1. The treatment temperature is generally 80-300℃, preferably 100-250℃, more preferably 120-200℃, and most preferably 120-160℃. The treatment time is generally 0.1-10h, preferably 0.2-8h, more preferably 0.3-6h, and most preferably 0.5-4h.

[0051] In this application, after step (3) above, drying and calcination can be performed directly, or washing can be performed before drying and calcination. In one example of this application, the washing can be performed using solvents commonly used in the art, including but not limited to one or more of water and organic solvents. The organic solvent is selected from one or more of methanol, ethanol, isopropanol, and acetonitrile.

[0052] In this application, the drying temperature in step (4) is generally 40-200℃, preferably 50-150℃, more preferably 60-120℃, and the drying time is generally 1-72h, preferably 2-60h, more preferably 4-48h.

[0053] In step (4) above, the calcination can be carried out in air or in an inert atmosphere. The calcination temperature is generally 200-800℃, preferably 250-750℃, more preferably 300-700℃, and most preferably 400-600℃. The calcination time is generally 1-12 hours. The calcination can be carried out by heating to the calcination temperature at a heating rate of 0.5-5℃ / min.

[0054] In this application, the organic amine in step (5) above can be a commonly used organic amine. In one example of this application, the organic amine is selected from one or more of methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, dibutylamine, tributylamine, ethylenediamine, ethanolamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. In another example of this application, the organic amine is selected from one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0055] In this application, the solvent may be a solvent commonly used in the art, including but not limited to one or more of water and organic solvents. The organic solvent is selected from one or more of methanol, ethanol, isopropanol, and acetonitrile.

[0056] In this application, the amounts of calcined molecular sieve catalyst, organic amine, and solvent used in step (5) above are conventional in the art, and those skilled in the art can directly and reasonably determine their specific amounts. In one example of this application, the calcined molecular sieve catalyst, organic amine, and solvent are mixed at a mass ratio of 1:0.05 to 5:1 to 30 (preferably 1:0.1 to 3:2 to 20, more preferably 1:0.2 to 1:3 to 15).

[0057] In a preferred embodiment of this application, the molecular sieve catalyst, organic amine and solvent mixed in step (5) above are reacted, wherein the reaction temperature is generally 40-300℃ (preferably 60-200℃, more preferably 80℃~140℃), and the reaction time is generally 1-72h (preferably 2-60h, more preferably 2-48h, most preferably 2~24h).

[0058] In one example of this application, in step (5) above, the mixed (reacted) molecular sieve catalyst is preferably washed with a solvent, wherein the solvent includes, but is not limited to, one or more of water, methanol, ethanol, isopropanol, and acetonitrile.

[0059] In this application, the drying temperature in step (5) above is generally 40-200℃ (preferably 50-160℃, more preferably 60-120℃), and the drying time is generally 1-72h (preferably 2-60h, more preferably 2-48h).

[0060] In step (5) above, the calcination can be carried out in air or in an inert atmosphere. The calcination temperature is generally 200-800℃, preferably 250-700℃, more preferably 300-600℃, and most preferably 350-500℃. The calcination time is generally 0.5-48h (preferably 1-36h, more preferably 1-24h, and most preferably 2-12h). The calcination can be carried out by heating to the calcination temperature at a heating rate of 0.5-5℃ / min.

[0061] Another aspect of this application provides a regenerated catalyst for a gas-phase Beckmann rearrangement reaction, said regenerated catalyst being regenerated according to the method of this application.

[0062] In one example of this application, the regenerated catalyst has a cyclohexanone oxime conversion rate of ≥99% (preferably ≥99.9%) and a caprolactam selectivity of ≥95% (preferably ≥96%, more preferably ≥96.5%, and even more preferably ≥97%). In another example of this application, the regenerated catalyst can operate stably for more than 1000 hours, preferably more than 1200 hours, more preferably more than 1500 hours, most preferably more than 1700 hours, and up to a maximum of 3000 hours, or 2800 hours, or 2500 hours, or 2200 hours.

[0063] In this application, "stable operation" means that the catalyst has a cyclohexanone oxime conversion rate of ≥99% (preferably ≥99.9%) and a caprolactam selectivity of ≥95% (preferably ≥96%, more preferably ≥96.5%, and even more preferably ≥97%) in the gas-phase Beckmann rearrangement reaction.

[0064] This application also provides a method for preparing caprolactam, the method comprising the following steps:

[0065] (1) Provide cyclohexanone oxime vapor;

[0066] (2) The cyclohexanone oxime vaporized product was subjected to a gas-phase Beckmann rearrangement reaction using a catalyst to obtain caprolactam.

[0067] The catalyst is a molecular sieve catalyst obtained according to the regeneration method of this application.

[0068] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0069] Example

[0070] Raw material source:

[0071] Methyl orthosilicate (Beijing Bailingwei Technology Co., Ltd.), Ethyl orthosilicate (Shanghai Aladdin Biochemical Technology Co., Ltd.), Propyl orthosilicate (Shanghai Maclean Biochemical Technology Co., Ltd.), Butyl orthosilicate (Shanghai Maclean Biochemical Technology Co., Ltd.);

[0072] Tetraethylammonium hydroxide (Shanghai Aladdin Biochemical Technology Co., Ltd.), Tetraethylammonium bromide (Shanghai Aladdin Biochemical Technology Co., Ltd.), Tetraethylammonium chloride (Shanghai Maclean Biochemical Technology Co., Ltd.);

[0073] Ethylenediamine (Shanghai Maclean Biochemical Technology Co., Ltd.), diethylenetriamine (Shanghai Maclean Biochemical Technology Co., Ltd.), tetraethylenepentamine (Shanghai Maclean Biochemical Technology Co., Ltd.);

[0074] Ultrapure water (Shenzhen PAINIC Instrument Equipment Co., Ltd.)

[0075] The deactivated catalyst was derived from the pilot-scale process of preparing caprolactam from the gas-phase rearrangement of cyclohexanone oxime, achieving a CHO conversion of 99.95% and a CPL selectivity of 96.37% at 1840 h. At the deactivation endpoint, the CHO conversion was 99.13% and the CPL selectivity was 94.87%.

[0076] equipment:

[0077] Muffle furnace (Pengda Kiln Factory, Luoyang High-tech Development Zone, Henan Province, model PD-MJ10); High pressure vessel (Shandong Weihai Xintai Chemical Machinery Co., Ltd., model GSHA); Catalyst evaluation device (Beijing Oushisheng Technology Co., Ltd., model EMC-3);

[0078] Test method: Periodic sampling is performed for quantitative GC analysis to calculate CHO conversion rate and CPL selectivity. The CHO conversion rate and CPL selectivity provided in the examples are average values ​​over the operating life.

[0079] Determining operational lifespan: The operational lifespan is defined as the time during which stable operation with CHO conversion rate > 99% and CPL selectivity > 95%.

[0080] The CHO conversion rate and CPL selectivity are calculated using the following formulas (1) and (2):

[0081]

[0082]

[0083] In the formula, x is the CHO conversion rate, y is the CPL selectivity, and m 进 The weight of CHO feed within a certain time period, m 出 n represents the weight of CHO in the reaction products over a certain period of time. CPL n is the number of moles converted into CPL within a certain time period. CHO This represents the molar amount of CHO converted within a certain time period.

[0084] Example 1

[0085] 50g of deactivated molecular sieve was heated to a gradient temperature of 250℃ in a 10% oxygen atmosphere (90% nitrogen) at a heating rate of 0.5℃ / min and held for 24h. Then, it was calcined at 400℃ for 48h at a heating rate of 0.2℃ / min, yielding 43g of calcined molecular sieve solid. 45.67g (0.3mol) of methyl orthosilicate, 55.22g of 40% (0.15mol) tetraethylammonium hydroxide aqueous solution, and 236.87g (15mol) of ultrapure water were mixed and hydrolyzed at 20℃ for 4h. The solution and 43g of calcined molecular sieve solid were then added to an autoclave and reacted at 120℃ under autogenous pressure for 4h to obtain the product system. The product system was separated, the wet solid was washed with 95% ethanol, dried at 60℃ for 24h, and then calcined in a muffle furnace at 400℃ for 12h to obtain 40g of molecular sieve solid. 40g of molecular sieve solid, 8g of ethylenediamine, and 120g of ultrapure water were added to a high-pressure reactor and reacted at 80℃ for 24h under autogenous pressure to obtain the product system. The product system was separated, the wet solid was washed with 99.9% methanol, dried at 60℃ for 48h, and then calcined in a muffle furnace at 350℃ for 12h to obtain the regenerated molecular sieve.

[0086] An ethanolic solution containing 20% ​​cyclohexanone oxime was prepared using nitrogen as the carrier gas at a space velocity of 0.8 h⁻¹. -1Cyclohexanone oxime / ethanol solution was mixed with ammonia and passed through a bed at 360°C to undergo a rearrangement reaction to generate caprolactam. The conversion rate of cyclohexanone oxime was 99.99%, the selectivity of caprolactam was 97.01%, and the system operated stably for 1520 hours.

[0087] Comparative Example 1 (without organic amine modification)

[0088] 50g of deactivated molecular sieve was heated to a gradient temperature of 250℃ in a 10% oxygen atmosphere (90% nitrogen) at a heating rate of 0.5℃ / min and held for 24h. Then, it was calcined at 400℃ for 48h at a heating rate of 0.2℃ / min, yielding 43g of calcined molecular sieve solid. 45.67g (0.3mol) of methyl orthosilicate, 55.22g (0.15mol) of 40% (15mol) tetraethylammonium hydroxide aqueous solution, and 236.87g (15mol) of ultrapure water were mixed and hydrolyzed at 20℃ for 4h. The solution and 43g of calcined molecular sieve solid were then added to an autoclave and reacted at 120℃ under autogenous pressure for 4h to obtain the product system. The product system was separated, the wet solid was washed with 95% ethanol, dried at 60℃ for 24h, and then calcined in a muffle furnace at 400℃ for 12h to obtain the regenerated molecular sieve.

[0089] An ethanolic solution containing 20% ​​cyclohexanone oxime was prepared using nitrogen as the carrier gas at a space velocity of 0.8 h⁻¹. -1 Cyclohexanone oxime / ethanol solution was mixed with ammonia and passed through a bed at 360°C to undergo a rearrangement reaction to generate caprolactam. The conversion rate of cyclohexanone oxime was 99.82%, the selectivity of caprolactam was 92.31%, and the system operated stably for 316 hours.

[0090] Comparative Example 2 (without hydrolysis solution treatment)

[0091] 50g of deactivated molecular sieve was heated to a gradient temperature of 250℃ in a 10% oxygen atmosphere (90% nitrogen) at a heating rate of 0.5℃ / min and held for 24h. Then, it was calcined at 400℃ for 48h at a heating rate of 0.2℃ / min, yielding 43g of calcined molecular sieve solid. 40g of the solid molecular sieve, 8g of ethylenediamine, and 120g of ultrapure water were added to a high-pressure reactor and reacted at 80℃ under autogenous pressure for 24h to obtain the product system. The product system was separated, the wet solid was washed with 99.9% methanol, dried at 60℃ for 48h, and then calcined in a muffle furnace at 350℃ for 12h to obtain the regenerated molecular sieve.

[0092] An ethanolic solution containing 20% ​​cyclohexanone oxime was prepared using nitrogen as the carrier gas at a space velocity of 0.8 h⁻¹. -1 Cyclohexanone oxime / ethanol solution was mixed with ammonia and passed through a bed at 360°C to undergo a rearrangement reaction to generate caprolactam. The conversion rate of cyclohexanone oxime continued to decrease, reaching only 95.35% after 180 h, while the selectivity for caprolactam was 96.21%.

[0093] Example 2

[0094] 50g of deactivated molecular sieve was heated to a gradient temperature of 250℃ in a 10% oxygen atmosphere (90% nitrogen) at a heating rate of 0.5℃ / min and held for 24h. Then, it was calcined at 400℃ for 48h at a heating rate of 0.2℃ / min, yielding 42g of calcined molecular sieve solid. 62.40g (0.3mol) of tetraethyl orthosilicate, 78.81g (0.15mol) of 40% (15mol) tetraethylammonium bromide aqueous solution, and 222.71g (15mol) of ultrapure water were mixed and hydrolyzed at 20℃ for 3h. The solution and 42g of calcined molecular sieve solid were then added to an autoclave and reacted at 120℃ under autogenous pressure for 4h to obtain the product system. The product system was separated, the wet solid was washed with 95% ethanol, dried at 60℃ for 48h, and then calcined in a muffle furnace at 400℃ for 12h to obtain 40g of molecular sieve solid. 40g of molecular sieve solid, 8g of diethylenetriamine, and 120g of ultrapure water were added to a high-pressure reactor and reacted at 80℃ for 24h under autogenous pressure to obtain the product system. The product system was separated, the wet solid was washed with 99.9% methanol, dried at 100℃ for 24h, and then calcined in a muffle furnace at 350℃ for 12h to obtain the regenerated molecular sieve.

[0095] An ethanolic solution containing 20% ​​cyclohexanone oxime was prepared using nitrogen as the carrier gas at a space velocity of 0.8 h⁻¹. -1 Cyclohexanone oxime / ethanol solution was mixed with ammonia and passed through a bed at 360°C to undergo a rearrangement reaction to generate caprolactam. The conversion rate of cyclohexanone oxime was 99.99%, the selectivity of caprolactam was 97.02%, and the system operated stably for 1865 hours.

[0096] Example 3

[0097] 50g of deactivated molecular sieve was heated to a gradient temperature of 250℃ in a 10% oxygen atmosphere (90% nitrogen) at a heating rate of 0.5℃ / min and held for 24h. Then, it was calcined at 400℃ for 48h at a heating rate of 0.2℃ / min, yielding 42g of calcined molecular sieve solid. 79.33g (0.3mol) of propyl orthosilicate, 62.14g of 40% (0.15mol) tetraethylammonium chloride aqueous solution, and 232.72g (15mol) of ultrapure water were mixed and hydrolyzed at 30℃ for 4h. The solution and 42g of calcined molecular sieve solid were then added to an autoclave and reacted at 120℃ under autogenous pressure for 4h to obtain the product system. The product system was separated, the wet solid was washed with 95% ethanol, dried at 60℃ for 48h, and then calcined in a muffle furnace at 400℃ for 12h to obtain 40g of molecular sieve solid. 40g of molecular sieve solid, 8g of tetraethylenepentamine, and 120g of ultrapure water were added to a high-pressure reactor and reacted at 80℃ for 24h under autogenous pressure to obtain the product system. The product system was separated, the wet solid was washed with 99.9% methanol, dried at 100℃ for 48h, and then calcined in a muffle furnace at 350℃ for 12h to obtain the regenerated molecular sieve.

[0098] An ethanolic solution containing 20% ​​cyclohexanone oxime was prepared using nitrogen as the carrier gas at a space velocity of 0.8 h⁻¹. -1 Cyclohexanone oxime / ethanol solution was mixed with ammonia and passed through a bed at 360°C to undergo a rearrangement reaction to generate caprolactam. The conversion rate of cyclohexanone oxime was 99.98%, the selectivity of caprolactam was 96.96%, and the system operated stably for 1785 hours.

[0099] Example 4

[0100] 50g of deactivated molecular sieve was heated to a gradient temperature of 250℃ in a 10% oxygen atmosphere (90% nitrogen) at a heating rate of 0.5℃ / min and held for 24h. Then, it was calcined at 400℃ for 48h at a heating rate of 0.2℃ / min, yielding 42g of calcined molecular sieve solid. 96.16g (0.3mol) of butyl orthosilicate, 55.22g of 40% (0.15mol) tetraethylammonium hydroxide aqueous solution, and 236.87g (15mol) of ultrapure water were mixed and hydrolyzed at 20℃ for 4h. The solution and 42g of calcined molecular sieve solid were then added to an autoclave and reacted at 120℃ under autogenous pressure for 4h to obtain the product system. The product system was separated, the wet solid was washed with 95% ethanol, dried at 100℃ for 36h, and then calcined in a muffle furnace at 400℃ for 12h to obtain 40g of molecular sieve solid. 40g of molecular sieve solid, 8g of ethylenediamine, and 120g of ultrapure water were added to a high-pressure reactor and reacted at 80℃ for 24h under autogenous pressure to obtain the product system. The product system was separated, the wet solid was washed with 99.9% methanol, dried at 60℃ for 36h, and then calcined in a muffle furnace at 350℃ for 12h to obtain the regenerated molecular sieve.

[0101] An ethanolic solution containing 20% ​​cyclohexanone oxime was prepared using nitrogen as the carrier gas at a space velocity of 0.8 h⁻¹. -1 Cyclohexanone oxime / ethanol solution was mixed with ammonia and passed through a bed at 360°C to undergo a rearrangement reaction to generate caprolactam. The conversion rate of cyclohexanone oxime was 99.95%, the selectivity of caprolactam was 96.68%, and the system operated stably for 1745 hours.

[0102] Examples 5-12

[0103] Based on Example 1, the performance of the catalyst was evaluated as follows after changing the calcination temperature, time, heating gradient, and oxygen concentration in step (1):

[0104]

[0105]

[0106] Examples 13-19

[0107] Based on Example 1, the molar ratio of organosilicon compound, water, and quaternary ammonium template agent in step (2) and the liquid-solid mass ratio of solution and calcined molecular sieve in step (3), as well as the reaction temperature and reaction time, were changed. The performance evaluation of the catalyst is as follows:

[0108]

[0109]

[0110] Examples 20-27

[0111] Based on Example 1, the mass ratios of calcined molecular sieve, ethylenediamine, and solvent, as well as the treatment temperature and time, were varied. The performance evaluation of the catalyst is as follows:

[0112]

Claims

1. A method for regenerating a molecular sieve catalyst for a gas phase Beckmann rearrangement reaction, the method comprising the steps of: (1) calcining an already deactivated silicon molecular sieve; (2) mixing raw materials including an organosilicon compound, water, a template agent and performing a hydrolysis reaction to obtain a solution; (3) mixing the solution obtained in step (2) and the calcined molecular sieve obtained in step (1) and performing a first treatment to separate a molecular sieve solid; (4) drying and calcining the molecular sieve solid obtained in step (3); (5) mixing the calcined solid obtained in step (4) with an organic amine and a solvent and drying and calcining to obtain a regenerated molecular sieve.

2. The method of claim 1, wherein, In the step (1), the calcination temperature is 300-1000°C and the oxygen volume concentration during calcination is 0.1-30%.

3. The method of claim 1, wherein, In the step (1), the calcination temperature is 350-800°C, the calcination time is 2-60h and the oxygen volume concentration during calcination is 0.5-20%.

4. The method of claim 1, wherein, In the step (1), the calcination temperature is 400-600°C, the calcination time is 4-48h and the oxygen volume concentration during calcination is 1-10%.

5. The method of claim 1, wherein, In the step (1), the temperature is increased to 250-350°C at a temperature increase rate of 0.1-10°C / min, maintained for 0.5-48h and then increased to the calcination temperature at a temperature increase rate of 0.05-10°C / min.

6. The method of claim 1, wherein, In the step (1), the temperature is increased to 250-350°C at a temperature increase rate of 0.2-8°C / min, maintained for 1-36h and then increased to the calcination temperature at a temperature increase rate of 0.1-5°C / min.

7. The method of claim 1, wherein, In the step (1), the temperature is increased to 250-350°C at a temperature increase rate of 0.5-5°C / min, maintained for 1-24h and then increased to the calcination temperature at a temperature increase rate of 0.2-2°C / min.

8. The method of claim 1, wherein, The organosilicon compound includes an alkyl orthosilicate, an alkyl metasilicate or a combination thereof.

9. The method of claim 8, wherein, The alkyl orthosilicate includes a C1-C20 alkyl orthosilicate.

10. The method of claim 8, wherein, The alkyl orthosilicate is selected from one or more of methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate or butyl orthosilicate.

11. The method of claim 8, wherein, The alkyl metasilicate includes a C1-C20 alkyl metasilicate.

12. The method of claim 8, wherein, The alkyl metasilicate is selected from one or more of methyl metasilicate, ethyl metasilicate, propyl metasilicate or butyl metasilicate.

13. The method of claim 1, wherein, The template agent includes an organic amine, a quaternary ammonium salt, a metal complex and a proton sponge.

14. The method of claim 13, wherein, The template agent is selected from an organic amine, a quaternary ammonium salt or a combination thereof.

15. The method of claim 14, wherein, The organic amine includes methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, dibutylamine, tributylamine, ethylenediamine, ethanolamine or a combination thereof.

16. The method of claim 14, wherein, The quaternary ammonium salt is selected from one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium bromide, tetrapropylammonium bromide, tetraethylammonium chloride and tetrapropylammonium chloride.

17. The method of claim 1, wherein, The hydrolysis reaction in step (2) is performed at a temperature of 15-60°C for 1-6h.

18. The method of claim 1, wherein, The hydrolysis reaction in step (2) is performed at a temperature of 20-40°C for 2-4h.

19. The method of claim 1, wherein, In the step (2), the molar ratio of the organosilicon compound, water, and template agent is 1:10-500:0.01-10.

20. The method of claim 1, wherein, In the step (2), the molar ratio of the organosilicon compound, water, and template agent is 1:20-400:0.05-5.

21. The method of claim 1, wherein, In the step (2), the molar ratio of the organosilicon compound, water, and template agent is 1:50-250:0.1-1.

22. The method of claim 1, wherein, The solution obtained in the step (2) and the calcined molecular sieve obtained in the step (1) are mixed in a mass ratio of 1-50:1, the treatment temperature is 80-300°C, and the treatment time is 0.1-10h.

23. The method of claim 1, wherein, The solution obtained in the step (2) and the calcined molecular sieve obtained in the step (1) are mixed in a mass ratio of 2-40:1, the treatment temperature is 100-250°C, and the treatment time is 0.2-8h.

24. The method of claim 1, wherein, The solution obtained in the step (2) and the calcined molecular sieve obtained in the step (1) are mixed in a mass ratio of 3-20:1, the treatment temperature is 120-200°C, and the treatment time is 0.3-6h.

25. The method of claim 1, wherein, The solution obtained in the step (2) and the calcined molecular sieve obtained in the step (1) are mixed in a mass ratio of 4-20:1, the treatment temperature is 120-160°C, and the treatment time is 0.5-4h.

26. The method of claim 1, wherein, The drying temperature in the step (4) is 40-200°C, and the drying time is 1-72h.

27. The method of claim 1, wherein, The drying temperature in the step (4) is 50-150°C, and the drying time is 2-60h.

28. The method of claim 1, wherein, The drying temperature in the step (4) is 60-120°C, and the drying time is 4-48h.

29. The method of claim 1, wherein, In the step (4), the calcination temperature is 200-800°C, and the calcination time is 1-12h.

30. The method of claim 1, wherein, In the step (4), the calcination temperature is 250-750°C.

31. The method of claim 1, wherein, In the step (4), the calcination temperature is 300-700°C.

32. The method of claim 1, wherein, In the step (4), the calcination temperature is 400-600°C.

33. The method of claim 1, wherein, In the step (4), the calcination is performed at a temperature rising rate of 0.5-5°C / min to the calcination temperature.

34. The method of claim 1, wherein, The organic amine in the step (5) is selected from one or more of methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, tripropylamine, butylamine, dibutylamine, tributylamine, ethylenediamine, ethanolamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

35. The method of claim 1, wherein, The organic amine in the step (5) is selected from one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

36. The method of claim 1, wherein, In the step (5), the calcined molecular sieve catalyst, the organic amine, and the solvent are mixed in a mass ratio of 1:0.05-5:1-30.

37. The method of claim 1, wherein, In the step (5), the calcined molecular sieve catalyst, the organic amine, and the solvent are mixed in a mass ratio of 1:0.1-3:2-20.

38. The method of claim 1, wherein, In the step (5), the calcined molecular sieve catalyst, the organic amine, and the solvent are mixed in a mass ratio of 1:0.2-1:3-15.

39. The method of claim 1, wherein, In the step (5), the mixed molecular sieve catalyst, the organic amine, and the solvent are reacted, wherein the reaction temperature is 40-300°C, and the reaction time is 1-72h.

40. The method of claim 1, wherein, In the step (5), the mixed molecular sieve catalyst, the organic amine and the solvent are reacted, wherein the reaction temperature is 60-200℃, and the reaction time is 2-60h.

41. The method of claim 1, wherein, In the step (5), the mixed molecular sieve catalyst, the organic amine and the solvent are reacted, wherein the reaction temperature is 80-140℃, and the reaction time is 2-48h.

42. The method of claim 1, wherein, The calcination in the step (5) is carried out in air or inert atmosphere.

43. The method of claim 1, wherein, The calcination in the step (5) is carried out at a temperature of 200-800℃ for a time of 0.5-48h.

44. The method of claim 1, wherein, The calcination in the step (5) is carried out at a temperature of 250-700℃ for a time of 1-36h.

45. The method of claim 1, wherein, The calcination in the step (5) is carried out at a temperature of 300-600℃ for a time of 1-24h.

46. The method of claim 1, wherein, The calcination in the step (5) is carried out at a temperature of 350-500℃ for a time of 2-12h.

47. The method of claim 1, wherein, The calcination in the step (5) comprises heating to the calcination temperature at a heating rate of 0.5-5℃ / min.

48. A method for preparing caprolactam, comprising the steps of: (1) providing cyclohexanone oxime gas; (2) catalyzing the cyclohexanone oxime gas to carry out a gas phase Beckmann rearrangement reaction to obtain caprolactam, the catalyst is a molecular sieve catalyst obtained according to the method of any one of claims 1-47.

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