Preparation method of catalyst for gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, and method of gas-phase Beckmann rearrangement reaction of cyclohexanone oxime.
By introducing the mixing of molecular sieve mother liquor and KOH into the preparation method, combined with rotational molding and alkaline buffer solution treatment, the problem of high cost of all-silica-1 molecular sieve catalyst was solved, and a highly efficient gas-phase Beckmann rearrangement reaction of cyclohexanone oxime was achieved, which improved the catalytic activity and stability of the catalyst and promoted its industrial application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING RISUN TECH CO LTD
- Filing Date
- 2024-12-02
- Publication Date
- 2026-06-02
AI Technical Summary
The preparation cost of the all-silica-1 molecular sieve catalyst is high, and the crushing strength of the catalyst after molding is not ideal, which makes it impossible to realize industrial application.
A colloidal mixture was prepared by mixing molecular sieve mother liquor, organosilicon ester, and KOH. After crystallization, solid-liquid separation and drying were carried out to obtain molecular sieve raw powder. The powder was then prepared by rotational molding and calcination, followed by post-treatment with an alkaline buffer solution containing ammonium salt, ammonia water, and bromide salt to produce spherical catalysts.
This reduces the cost of molecular sieve synthesis, improves the catalytic activity and stability of the catalyst, enables long-term continuous production of caprolactam, and enhances the economics of the new gas-phase rearrangement process.
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Figure CN122124845A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalysts for the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, specifically to a method for preparing a catalyst for the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime and a method for the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime. Background Technology
[0002] Caprolactam is a major raw material for the production of three major series of products: nylon, industrial tire cord, and nylon engineering plastics, and its demand is relatively high. Caprolactam is generally obtained through the Beckmann rearrangement reaction of cyclohexanone oxime. Various solid acids can be used as catalysts in the gas-phase Beckmann rearrangement reaction, such as silica-alumina catalysts, solid phosphoric acid catalysts, boric acid catalysts, and high silica / alumina ratio MFI structure molecular sieve catalysts. Silicalite-1 molecular sieve, also known as all-silica or pure silica molecular sieve, was first successfully synthesized in 1978 by EMFlanigen et al. of Union Carbide Corporation, and belongs to the "Pentasil" family. The synthesis method of all-silica molecular sieve generally adopts the traditional organic raw material hydrothermal method. The silicon source is often solid silica, silica sol, white carbon black, or tetraethyl orthosilicate (TEOS), and the template agent is often tetrapropylammonium hydroxide (TPAOH), low-carbon hydrocarbon quaternary ammonium salts, or amine compounds, etc., crystallization is carried out at 170°C for three days. However, the synthesis cost of all-silica molecular sieves has remained high, hindering their industrialization.
[0003] CN1256967A discloses a method for preparing a molecular sieve catalyst containing an MFI structure for the conversion of cyclohexanone oxime to caprolactam. The basic premise of this method is to use acidic silica gel as a binder. Specifically, the method involves mixing a silica oligomer obtained by acidic hydrolysis of alkoxysilanes with an aqueous or alcohol-water dispersion of submicron particles of an MFI structure molecular sieve at pH ≤ 5, followed by emulsification, solidification, washing, and calcination to obtain gel microspheres.
[0004] Because ZSM-5 type all-silica molecular sieves have great difficulties in extrusion molding, tablet molding, and even rolling molding, even after molding, the crushing strength of the catalyst is not ideal (<60N / cm or <1kg / particle), making it impossible to achieve industrial application. Summary of the Invention
[0005] The purpose of this invention is to overcome the problem of high preparation cost of all-silica-1 molecular sieve catalysts in the prior art, and to provide a method for preparing a cyclohexanone oxime gas-phase Beckmann rearrangement reaction catalyst and a method for the cyclohexanone oxime gas-phase Beckmann rearrangement reaction. This preparation method has the characteristics of low cost and good economy, and the catalyst obtained has high catalytic activity and stability.
[0006] To achieve the above objectives, the present invention provides a method for preparing a gas-phase Beckmann rearrangement catalyst for cyclohexanone oxime, comprising:
[0007] (1) Mix molecular sieve mother liquor, organosilicate, organic template agent and KOH to obtain colloidal mixture;
[0008] The amounts of the molecular sieve mother liquor and the organosilicone ester are such that the mass ratio of SiO2 in the molecular sieve mother liquor to the mass ratio of organosilicone ester (calculated as SiO2) is 0.01-0.2:1.
[0009] The composition of the colloidal mixture satisfies that the molar ratio of SiO2, KOH, organic template agent, and water is 1:(0.01-0.1):(0.04-0.15):(15-45);
[0010] (2) The colloidal mixture is subjected to a crystallization reaction;
[0011] (3) The crystallization product obtained in step (2) is subjected to solid-liquid separation to obtain molecular sieve wet material and crystallization mother liquor; the molecular sieve wet material is dried to obtain molecular sieve raw powder;
[0012] Optionally, the crystallization mother liquor may be concentrated, and then the process may return to step (1) to provide the molecular sieve mother liquor.
[0013] (4) The molecular sieve powder is optionally mixed with a binder, and then rotated to form spherical particles;
[0014] (5) The spherical particles are roasted and then contacted with an alkaline buffer solution containing ammonium salt, ammonia water, magnesium salt and bromide salt.
[0015] The second aspect of the present invention provides a method for the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, the method comprising: under the conditions of the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, in the presence of a solvent, contacting cyclohexanone oxime with a catalyst to react, wherein the catalyst is the gas-phase Beckmann rearrangement reaction catalyst of cyclohexanone oxime prepared by the preparation method described in the first aspect.
[0016] Preferably, the contact takes place in a fixed-bed or moving-bed reactor.
[0017] The preparation method provided by this invention can effectively utilize the mother liquor of all-silica molecular sieve synthesis, thereby improving the synthesis yield of molecular sieves, shortening the crystallization time, and reducing the synthesis cost of molecular sieves. Simultaneously, this invention breaks through the technical biases in conventional all-silica-1 molecular sieve synthesis by creatively introducing an appropriate amount of KOH during the synthesis process. Combined with the reuse of the molecular sieve mother liquor, this yields a nearly neutral all-silica-1 molecular sieve powder with high crystallinity, fine particles, and a ZSM-5 structure. After rolling and molding, the powder undergoes post-treatment using an alkaline buffer solution containing ammonium, magnesium, and bromide salts. Through the combined effect of molecular sieve synthesis and post-treatment conditions, the resulting spherical catalyst exhibits good crushing strength. In a moving bed or fixed bed reaction system, using this spherical ZSM-5 structured all-silica molecular sieve as a catalyst for the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime to prepare caprolactam enables long-cycle, continuous production of caprolactam. While maintaining the selectivity of caprolactam essentially unchanged, it can improve the conversion rate of cyclohexanone oxime, extend catalyst life, and enhance the economics of the new gas-phase rearrangement process technology. Attached Figure Description
[0018] Figure 1 These are morphological photographs of the catalyst prepared in Example 1 of this invention. Detailed Implementation
[0019] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0020] The first aspect of this invention provides a method for preparing a gas-phase Beckmann rearrangement catalyst for cyclohexanone oxime, comprising:
[0021] (1) Mix molecular sieve mother liquor, organosilicate, organic template agent and KOH to obtain colloidal mixture;
[0022] The amounts of the molecular sieve mother liquor and the organosilicone ester are such that the mass ratio of SiO2 in the molecular sieve mother liquor to the mass ratio of organosilicone ester (calculated as SiO2) is 0.01-0.2:1.
[0023] The composition of the colloidal mixture satisfies that the molar ratio of SiO2, KOH, organic template agent, and water is 1:(0.01-0.1):(0.04-0.15):(15-45);
[0024] (2) The colloidal mixture is subjected to a crystallization reaction;
[0025] (3) The crystallization product obtained in step (2) is subjected to solid-liquid separation to obtain molecular sieve wet material and crystallization mother liquor; the molecular sieve wet material is dried to obtain molecular sieve raw powder;
[0026] Optionally, the crystallization mother liquor may be concentrated, and then the process may return to step (1) to provide the molecular sieve mother liquor.
[0027] (4) The molecular sieve powder is optionally mixed with a binder, and then rotated to form spherical particles;
[0028] (5) The spherical particles are roasted and then contacted with an alkaline buffer solution containing ammonium salt, ammonia water, magnesium salt and bromide salt.
[0029] According to the present invention, preferably, the composition of the colloidal mixture satisfies the following molar ratio: SiO2, KOH, organic template agent, and water is 1:(0.02-0.08):(0.08-0.2):(15-30). Adopting the above preferred embodiment is beneficial for reducing the amount of organic template agent used while ensuring the synthesis quality of the molecular sieve.
[0030] In this invention, the SiO2 in the colloidal mixture refers to the sum of the molar amount of silicon in the molecular sieve mother liquor (calculated as SiO2) and the molar amount of silicon in the organosilicate (calculated as SiO2). The water in the colloidal mixture can be entirely derived from the molecular sieve mother liquor and water introduced from other component raw materials (e.g., organic template agents), or a small amount of water can be added to adjust the balance of the molecular sieve synthesis molar ratio. Those skilled in the art can make adjustments according to actual needs.
[0031] According to some preferred embodiments of the present invention, the amounts of the molecular sieve mother liquor and the organosilicate are such that the mass ratio of SiO2 in the molecular sieve mother liquor to the mass ratio of the organosilicate based on SiO2 is 0.02-0.15:1, for example, typical but not limiting mass ratios such as 0.02:1, 0.05:1, 0.1:1, 0.15:1, or a range between the two. In the above preferred embodiments, it is beneficial to further improve the relative crystallinity of the molecular sieve.
[0032] In this invention, the "molecular sieve mother liquor" mentioned in step (1) can be a liquid mixture obtained by solid-liquid separation after conventional all-silica molecular sieve crystallization synthesis, or it can be provided by the crystallization mother liquor mentioned in step (4). By controlling the proportion of molecular sieve mother liquor reuse and the composition of the colloidal mixture, it is possible to prepare all-silica molecular sieves with MFI topological structures with a lower amount of organic template agent. This is beneficial for reducing the consumption of raw materials, especially expensive organic template agents, and can effectively reduce environmental pollution. At the same time, the presence of molecular sieve microcrystals in the mother liquor can act as seed crystals, thereby helping to shorten the crystallization time and improve the relative crystallinity and yield of the molecular sieve.
[0033] According to some preferred embodiments of the present invention, the molecular sieve mother liquor includes an organic template agent, silicon species, water, and optionally KOH.
[0034] Preferably, the molecular sieve mother liquor contains 5-20 wt% organic template agent, preferably 6-10 wt%, 1-10 wt% silicon species (calculated as SiO2), preferably 1.5-5 wt%, 60-90 wt% water, preferably 65-85 wt%, and 0.1-1 wt% KOH, preferably 0.2-0.8 wt%. The silicon species in the molecular sieve mother liquor exist in the form of SiO2, silicic acid and its oligomers, and molecular sieve microcrystals. In this invention, the silicon species in the molecular sieve mother liquor refer to the total amount of silicon element (calculated as SiO2) in the molecular sieve mother liquor.
[0035] According to the present invention, the molecular sieve mother liquor may also contain low-carbon alcohols, which may originate from the hydrolysis of organosilicon esters during crystallization or alcohols additionally introduced during conventional all-silica molecular sieve crystallization. The present invention does not impose any particular limitation thereon. Preferably, the alcohol content in the molecular sieve mother liquor is 1-15 wt%.
[0036] According to some preferred embodiments of the present invention, the molar ratio of alcohol to SiO2 in the colloidal mixture is (4-9):1. It is understood that the mixing process in step (1) may or may not involve the addition of additional alcohol, such that the alcohol in the colloidal mixture is entirely supplied by the molecular sieve mother liquor, or by the molecular sieve mother liquor and any additional alcohol, as long as the above molar ratio range is met.
[0037] In a further preferred embodiment, no additional alcohol is introduced during the mixing process described in step (1), except for alcohols that may be generated by the hydrolysis of organosilicon esters or introduced from the mother liquor.
[0038] According to some preferred embodiments of the present invention, in the initial synthesis process, a molecular sieve mother liquor is first prepared, and then the process is continuously carried out according to the aforementioned method. Preferably, the method for preparing the molecular sieve mother liquor includes:
[0039] a. Mix organosilicate, organic template agent, KOH and water to obtain a colloidal mixture;
[0040] The composition of the colloidal mixture satisfies that the molar ratio of SiO2, KOH, organic template agent, and water is 1:(0.01-0.1):(0.04-0.15):(15-45);
[0041] b. Perform a crystallization reaction on the colloidal mixture;
[0042] c. Perform solid-liquid separation on the crystallized product obtained in step (2) to obtain crystallization mother liquor;
[0043] d. The crystallization mother liquor is optionally concentrated to obtain molecular sieve mother liquor.
[0044] The selection range of materials and crystallization conditions in the above-mentioned molecular sieve mother liquor preparation process are the same as those in the preparation method of MFI topological structure all-silica molecular sieves, which will be described in detail later.
[0045] According to the present invention, preferably, the composition of the colloidal mixture satisfies the following molar ratio: SiO2, KOH, organic template agent, and water is 1:(0.02-0.08):(0.08-0.2):(20-40). Adopting the above preferred embodiment is beneficial for reducing the amount of organic template agent used while ensuring the synthesis quality of the molecular sieve.
[0046] In this invention, the SiO2 in the colloidal mixture refers to the sum of the molar amount of silicon in the molecular sieve mother liquor (calculated as SiO2) and the molar amount of silicon in the organosilicate (calculated as SiO2); the water in the colloidal mixture can be entirely derived from the molecular sieve mother liquor and water introduced from the raw materials of other components, or a small amount of water can be added to adjust the balance of the molecular sieve synthesis molar ratio. Those skilled in the art can make adjustments according to actual needs.
[0047] According to the present invention, preferably, the silicon source is methyl orthosilicate and / or ethyl orthosilicate, more preferably ethyl orthosilicate.
[0048] In this invention, the silicon source can be obtained commercially. In commercially available organosilicone esters, in addition to the effective components, impurities such as alcohols may also be present. The inventors of this invention have found in experiments that selecting a silicon source with a purity of not less than 98wt%, a platinum-cobalt color of not more than 20mg / L, and a Cl ion concentration of not more than 50ppm as a raw material is beneficial to improving the selectivity of the catalyst.
[0049] In this invention, the purity of the silicon source refers to the content of the effective component in the silicon source. For example, when the effective component of the silicon source is tetraethyl orthosilicate, its purity refers to the mass fraction of tetraethyl orthosilicate in the silicon source.
[0050] The platinum-cobalt colorimetric method uses the color exhibited in 1 L of water containing 1 mg of Pt(Ⅳ) and 2 mg of cobalt chloride hexahydrate(Ⅱ) as a standard unit of colorimetry, generally referred to as 1 degree. In this invention, following the platinum-cobalt colorimetric method, a set of standard colors of 2, 4, 6, 8, 10, 12, 14, 16, 18, and 20 degrees are prepared, and then compared to determine the colorimetry of the silicon source.
[0051] According to the present invention, the organic template agent can be a conventional choice in the art. Preferably, the organic template agent is a quaternary ammonium base compound, preferably tetrapropylammonium hydroxide and / or tetraethylammonium hydroxide, and more preferably tetrapropylammonium hydroxide.
[0052] As is known to those skilled in the art, commercially available alkyl quaternary ammonium bases typically contain small amounts of sodium ions. In the prior art, when using organic bases as template agents alone to synthesize all-silica-1 molecular sieves, the requirements for sodium ions in the alkyl quaternary ammonium bases are quite strict, typically requiring 5-10 ppm. In this invention, by introducing KOH, the requirements for sodium ion content in the alkyl quaternary ammonium bases can be relaxed, and high-quality all-silica-1 molecular sieves can still be synthesized even when the sodium ion content exceeds 10 ppm.
[0053] According to the present invention, preferably, the bromide ion content in the organic template agent is less than 1.5 wt%, and more preferably 0.5-1.5 wt%. The inventors of the present invention have discovered that using an organic template agent containing a certain amount of bromide ions as a synthetic raw material, such as tetrapropylammonium hydroxide containing a certain amount of tetrapropylammonium bromide, is beneficial to further improve the selectivity of caprolactam. The reason for this may be that the bromide present in the organic amine is conducive to the formation of ethyl-ε-caprolactamimide, which can be further converted into caprolactam through hydrolysis, ultimately resulting in improved catalyst selectivity.
[0054] Preferably, the iron ion content in the organic template agent is not greater than 10 ppm.
[0055] Preferably, the organic template agent contains less than 500 ppm sodium ions, no more than 550 ppm free acid, less than 0.2 wt% carbonate ions, and an APHA color value not exceeding 100. The free acid includes, for example, any one or more of formic acid, acetic acid, and propionic acid.
[0056] According to the present invention, a higher crystallization temperature and a shorter crystallization time are preferably used for the crystallization in step (2). Preferably, in step (2), the crystallization temperature is 95-150°C, more preferably 100-150°C, and the time is 0.5-5 days, more preferably 1-5 days. By adopting the above-mentioned preferred embodiment, with the introduction of appropriate KOH and molecular sieve mother liquor, combined with high-temperature rapid crystallization, it is beneficial to improve the crystallinity of the molecular sieve, thereby further improving the stability of the catalyst.
[0057] In this invention, to facilitate the adjustment of the molar ratio balance in the colloidal mixture, preferably, in step (3), the crystallization mother liquor is concentrated, and then returned to step (1) to provide the molecular sieve mother liquor. The concentration can be carried out by distillation, with water continuously added during the distillation process. By purifying the active ingredient (silicon source) and unreacted organic template agent in the liquid phase through distillation, the purpose of recycling the molecular sieve mother liquor is achieved, increasing the concentration of organic template agent and silicon oxide, so that the composition of the concentrated crystallization mother liquor meets the above-mentioned definition range of molecular sieve mother liquor.
[0058] Preferably, the concentration conditions in step (3) include a temperature of 50-100℃, preferably 70-90℃.
[0059] According to the present invention, in step (3), the crystallized product obtained in step (2) is subjected to solid-liquid separation, which can be performed using various methods conventionally used in the art. For example, the solid-liquid separation can be performed by membrane filtration, wherein the pore size of the filter membrane used in the membrane filtration is preferably no greater than 200 nm, and more preferably no greater than 100 nm. Preferably, the filter membrane is an inorganic membrane.
[0060] According to the present invention, preferably, prior to the drying process, in order to completely remove the dissolved components other than the molecular sieve crystals remaining in the crystals, a washing treatment may be performed using an organic solvent such as methanol or ethanol, or water. According to a specific embodiment of the present invention, the washing includes: washing the wet molecular sieve material until the pH value of the washing water is 9-9.4.
[0061] The present invention has a wide range of options for the drying process in step (3). Preferably, the drying conditions include: a temperature of 100-120°C and a time of 12-48h.
[0062] In this invention, preferably, the binder is a precursor of water or silicon dioxide. The silicon dioxide precursor can be selected from any substance that can be converted into silicon dioxide by calcination, and this invention does not have any particular limitation. Preferably, the silicon dioxide precursor is silica sol and / or silica fume, more preferably silica sol. The SiO2 content in the silica sol is 20-45% by weight.
[0063] In this invention, the rotational molding in step (4) can be performed using conventional methods in the art, with the aim of obtaining spherical particles. Preferably, the particle size of the spherical particles is 0.1-3 mm, more preferably 0.2-2.5 mm. Preferably, the rotational molding is performed in a rotary molding machine.
[0064] According to some preferred embodiments of the present invention, the conditions for rotary forming include: a turntable inclination angle of 40-55 degrees, preferably 45-50 degrees; to maintain a good ratio between the material and spherical particles of different sizes, it is generally desirable that the relationship between the turntable diameter D and the turntable depth H is H = (0.1-0.5)D, preferably H = (0.1-0.4)D; a turntable rotation speed of 10-50 rpm, preferably 20-40 rpm; a residence time (referring to the average time from the addition of the molecular sieve raw material to the formation of the target spherical particles and their departure from the turntable forming machine) of 10-600 minutes, preferably 30-180 minutes; a processing capacity of the turntable forming machine, based on the amount of catalyst produced per hour, of 20-100 kg / h, preferably 60 kg / h; and a material storage amount in the turntable, referring to the amount of micro- or small spherical catalyst particles in the turntable that have not reached the qualified diameter, preferably controlled at 1 / 10-1 / 4 of the processing capacity.
[0065] According to some preferred embodiments of the present invention, step (4) of rotational forming includes:
[0066] (4-1) Select a first powder sample with a particle size of 200-500 mesh from the solid material obtained by crushing, mix the first powder sample with a portion of the binder, and perform a first rotational molding to obtain a first spherical particle with a particle size of 0.1-0.8 mm, wherein the mass ratio of the first powder sample to the first binder is 1:(0.2-1);
[0067] (4-2) Select a second powder sample with a particle size of 100-1000 mesh from the solid material obtained by crushing. Mix the second powder sample, the remaining binder and the first spherical particles, and perform a second rotation molding to obtain a second spherical particle with a particle size of 1.3-2.5 mm. The mass ratio of the second powder sample to the remaining binder is 1:(0.001-0.5).
[0068] (4-3) Dry the second spherical particles obtained in step (4-2).
[0069] In this invention, the second powder sample and the remaining binder in step (4-2) can be added to the rotary molding machine separately or added after being pre-mixed evenly. More preferably, the second powder sample and the remaining binder are mixed and then re-pulverized to below 30 mesh before being added to the rotary molding machine having the first spherical particles described in step (4-1).
[0070] In this invention, the weight ratio of the first powder sample to the second powder sample can be any ratio as needed, and can be adjusted at any time according to the spheroidization of the molecular sieve; this invention does not impose any particular limitations. Preferably, the weight ratio of the first powder sample to the second powder sample is 1:20-100.
[0071] The terms "first" and "second" in "first rotational forming" and "second rotational forming" are only used to distinguish rotational forming operations in different steps, and both can be performed according to the aforementioned rotational forming conditions.
[0072] To further improve the performance of the catalyst product, preferably, an additive is introduced during the rotational molding process in step (4). The additive is selected from at least one of the following: guar gum powder, graphite, activated carbon, paraffin wax, glycerin, citric acid, starch, polyethylene glycol, polyvinyl alcohol, nitric acid, hydrochloric acid, acetic acid, formic acid, ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide.
[0073] Preferably, the amount of additive introduced is 1-5 wt%, based on the dry weight of the molecular sieve powder.
[0074] According to some preferred embodiments of the present invention, the preparation method further includes drying the product obtained by rotational molding. The present invention does not particularly limit the drying method, as long as moisture is removed. The drying method includes, but is not limited to, natural drying, heat drying, and forced-air drying. The drying temperature can be 80-200℃, and the drying time can be 2-24 hours.
[0075] According to some preferred embodiments of the present invention, after the rotational molding in step (4) (preferably before the drying), the preparation method further includes: polishing the product obtained by rotational molding. The polishing process can be carried out in a manner conventional in the art. Specifically, for example, the product obtained by rotational molding is blown at 20-50°C, and water is added multiple times (e.g., 3-10 times) during the blowing process, and then tightened.
[0076] According to some preferred embodiments of the present invention, the calcination conditions in step (5) include: a temperature of 200-600℃, preferably 250-550℃, and a time of 1-20h.
[0077] The inventors of this invention discovered in their research that post-treatment of the calcined product with an alkaline buffer solution containing ammonium salt, ammonia water, magnesium salt, and bromide salt can further improve the catalytic performance of the catalyst, resulting in higher total selectivity and total yield of caprolactam.
[0078] According to the present invention, preferably, the pH of the alkaline buffer solution is 8.5-13.5, more preferably 10-12, and even more preferably 11-11.5.
[0079] Preferably, based on the total amount of the alkaline buffer solution, the content of magnesium salts (calculated as Mg) is 1-500 ppm, more preferably 10-300 ppm; and the content of bromide salts (calculated as Br) is 1-500 ppm, more preferably 5-300 ppm. Using the above-mentioned preferred embodiments is beneficial for further improving the catalytic performance of the obtained catalyst, exhibiting higher total selectivity and total yield of caprolactam compared to catalysts obtained through existing post-processing methods.
[0080] The present invention has a wide range of choices for the ammonium salt, magnesium salt and bromide salt, and can use conventional soluble salts in the art that can provide nitrogen, magnesium and bromine elements.
[0081] Preferably, the ammonium salt is selected from ammonium nitrate and / or ammonium acetate.
[0082] Preferably, the magnesium salt is selected from at least one of magnesium nitrate hexahydrate, magnesium acetate, magnesium chloride, magnesium sulfate, and magnesium hydrogen phosphate.
[0083] Preferably, the bromide salt is tetrapropylammonium bromide.
[0084] The present invention has a wide range of solvent options for the alkaline buffer solution, with water being the preferred solvent.
[0085] Preferably, the alkaline buffer solution includes ammonia, an aqueous solution of ammonium salt, magnesium salt, and bromide salt.
[0086] Preferably, the weight ratio of ammonia water to ammonium salt aqueous solution is 1-3:1.
[0087] Preferably, the concentration of the ammonia solution is 5-30 wt%, more preferably 20-30 wt%.
[0088] Preferably, the concentration of the ammonium salt aqueous solution is 0.5-10 wt%.
[0089] According to the present invention, preferably, the amount of alkaline buffer solution used is 500-1500 parts by weight, more preferably 700-1200 parts by weight, relative to 100 parts by weight of calcined spherical particles.
[0090] Preferably, the contact conditions include: a temperature of 50-120°C, more preferably 70-100°C; and a pressure of 0.5-10 kg / cm². 2 The preferred value is 1.5-4 kg / cm². 2 The time is 0.1-5 hours, preferably 1-3 hours.
[0091] According to the present invention, the contact process can be repeated. The present invention does not particularly limit the number of repetitions, but can determine them based on the effectiveness of the contact, with the aim of improving the performance of the catalyst; for example, it can be repeated 1-3 times.
[0092] Preferably, step (5) may further include: solid-liquid separation, washing and drying of the contacted product.
[0093] The present invention does not particularly limit the washing agent used in the washing process; for example, it can be water. Specifically, the washing process may include washing until the pH of the filtrate is 9-10.5. The drying method can be carried out according to any existing technology in the art, such as heating drying, forced air drying, or natural drying. The drying temperature can be 100-120°C, and the drying time can be 10-24 hours. The catalyst obtained by washing and drying the contacted material is beneficial for improving the conversion rate of cyclohexanone oxime and the selectivity of caprolactam when used in the preparation of caprolactam from cyclohexanone oxime.
[0094] A second aspect of the present invention provides a method for the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, the method comprising: reacting cyclohexanone oxime with a catalyst in the presence of a solvent under the conditions of the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, wherein the catalyst is a gas-phase Beckmann rearrangement reaction catalyst of cyclohexanone oxime prepared by the preparation method described in the first aspect.
[0095] Using the molecular sieve catalyst provided by this invention in the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime can improve the conversion rate of cyclohexanone oxime and the selectivity of caprolactam, and can also extend the catalyst lifetime and improve the economics of the new gas-phase rearrangement process technology.
[0096] Preferably, the contact takes place in a fixed-bed or moving-bed reactor.
[0097] Preferably, the solvent is a C1-C6 fatty alcohol, and more preferably at least one of methanol, ethanol and n-propanol.
[0098] Preferably, the molar ratio of the solvent to cyclohexanone oxime is (2-10):1.
[0099] According to the present invention, preferably, the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime is carried out under an inert atmosphere. In the present invention, the inert atmosphere is provided by an inert gas, preferably selected from at least one of nitrogen, helium, argon and neon, and more preferably nitrogen.
[0100] According to the present invention, preferably, the molar ratio of the inert gas to cyclohexanone oxime is 10-80:1, more preferably 20-40:1.
[0101] According to some preferred embodiments of the present invention, the gas-phase Beckmann rearrangement reaction conditions for cyclohexanone oxime include: a weight hourly space velocity (WHSV) of 0.1-10 h⁻¹ for cyclohexanone oxime. -1 Preferably 0.5-5h -1 The reaction temperature is 300-500℃, preferably 350-400℃, and more preferably 360-390℃; the reaction pressure is 0.05-0.8MPa, preferably 0.1-0.5MPa. Unless otherwise specified, all pressures mentioned in this invention are gauge pressures.
[0102] According to the present invention, preferably, the method further includes mixing cyclohexanone oxime with water, and then contacting the catalyst in the presence of the solvent to carry out a gas-phase Beckmann rearrangement reaction. This preferred embodiment is more advantageous in improving the stability of the catalyst. Preferably, the molar ratio of cyclohexanone oxime to water is 1:(0.01-2.5).
[0103] The present invention will be described in detail below through embodiments.
[0104] In the following examples, unless otherwise specified, the tetraethyl orthosilicate used was purchased from Zhejiang Kaihua Synthetic Materials Co., Ltd., with a purity of 99 wt%, an ethanol content of no more than 1 wt%, a platinum-cobalt color of no more than 20 mg Pt-Co / L, and a Cl ion content of no more than 50 ppm. The tetrapropylammonium hydroxide used was purchased from Guangzhou Dayou Fine Chemical Co., Ltd., with a tetrapropylammonium hydroxide content of 22.5 wt%, a sodium ion content of no more than 500 ppm, a bromide ion content of no more than 1.5 wt%, a carbonate ion content of no more than 0.2 wt%, an APHA color of no more than 100, a potassium ion content of no more than 1.5% wt%, an iron ion content of no more than 10 ppm, an acetic acid content of no more than 500 ppm, and formic acid and propionic acid contents of no more than 50 ppm. The potassium hydroxide used was purchased from Sinopharm Group.
[0105] Preparation Example - Synthesis of Molecular Sieve Mother Liquor
[0106] Under stirring conditions, 136 kg of a 22.5 wt% tetrapropylammonium hydroxide aqueous solution, 208 kg of tetraethyl orthosilicate, 2.24 kg of KOH, and 344.6 kg of water were mixed and stirred at room temperature for 4 hours to obtain a colloidal mixture; wherein the molar ratio of tetraethyl orthosilicate:tetrapropylammonium hydroxide:KOH:water, calculated as SiO2, was 1:0.15:0.04:25; the above colloidal mixture was fed into a 1M... 3 In a stainless steel reactor, the hydrothermal system was crystallized at 120°C for 2 days with a stirring rate of 45 rpm to obtain a molecular sieve slurry; then, it was filtered under heat on a 50 nm membrane tube to obtain the crystallization mother liquor, which was collected and reserved for use in the example.
[0107] Example 1
[0108] (1) The crystallization mother liquor obtained in the preparation example was concentrated at 70-90℃, with water added continuously during the process, to obtain 210 kg of molecular sieve mother liquor. After analysis and adjustment, the content of SiO2 was 2.31%, the content of TPAOH was 7.0%, the content of ethanol was 3.1%, the content of water was 87%, the content of KOH was 0.54%, and the content of other impurities was 0.05%.
[0109] (2) Under stirring conditions, the above 210 kg molecular sieve mother liquor, tetraethyl orthosilicate (TEOS), tetrapropylammonium hydroxide (TPAOH), ethanol, KOH and water are mixed at room temperature for 4 h to obtain a colloidal mixture, wherein the mass ratio of SiO2 in the molecular sieve mother liquor to the mass ratio of organosilicon ester based on SiO2 is 0.081:1; and the molar ratio of SiO2:ethanol:tetrapropylammonium hydroxide:KOH:water in the colloidal mixture is 1:4:0.15:0.04:25.
[0110] (3) The above colloidal mixture was fed into a stainless steel reactor and crystallized in an alcohol-hydrothermal system at 120°C for 2 days with a stirring rate of 45 rpm to obtain a molecular sieve slurry. Then, it was filtered through a 50 nm membrane tube to obtain a crystallization mother liquor, which was bottled for use in the example. The molecular sieve slurry was then circulated and washed with a circulating water temperature of 40-60°C and a washing water volume of 6-8 M. 3 The washing water was washed until the pH value of the crystallized product reached approximately 9.1-9.3. The slurry was then concentrated and dried at 120℃ for 24 hours to obtain the molecular sieve powder. The yield of the molecular sieve was calculated to be 95%.
[0111] A small amount of molecular sieve powder was calcined at 550℃ for 6 hours and X-ray diffraction analysis was performed. The results showed that the standard XRD pattern of the MFI structure was consistent with that described in the literature (Microporous Materials, Vol 22, p637, 1998), indicating that the molecular sieve has an MFI crystal structure.
[0112] (4) The molecular sieve powder obtained in step (3) is pulverized in a pulverizer. 2 kg of the pulverized molecular sieve raw material (100-1000 mesh) is placed in a rotary forming machine. The rotary forming machine has a rotary diameter of 1.2 m, a rotary depth of 450 mm, a rotary inclination angle of 50°, and a rotary speed of 30 rpm. 1.5 kg of deionized water is sprayed into the machine to obtain the first spherical particles with a diameter of approximately 0.2-0.8 mm.
[0113] Take another 220 kg of pulverized molecular sieve raw material (200-800 mesh) and mix it evenly with 110 kg of alkaline silica sol (SiO2 content 30% by weight), then pulverize it again. Take particles smaller than 30 mesh and add 300 kg of the material at a uniform speed to the rotary forming machine containing the first spherical particles, completing the addition within 240 minutes. During the process, sieve the material multiple times using 12 mesh and 9 mesh sieves to obtain approximately 160 kg of second spherical particles with a diameter of 1.7-2.2 mm. The spherical particles smaller than 1.7 mm are returned to the rotary forming machine to continue growing.
[0114] The 90 kg of the second spherical particles obtained above were blown with air at 45°C, with trace amounts of water added several times during the process, and tightened for 2 hours. They were then dried at 120°C for 24 hours, and finally calcined at 550°C for 10 hours. The final calcined product had a molecular sieve content of ~85%.
[0115] (5) Add 90 kg of the above-mentioned roasted product and 900 kg of alkaline buffer solution (the alkaline buffer solution for the nitrogen-containing compound is a mixture of ammonia water and ammonium nitrate aqueous solution, wherein the content of ammonia water is 26 wt%, the content of ammonium nitrate in the ammonium nitrate aqueous solution is 7.5 wt%, the weight ratio of ammonia water to ammonium nitrate aqueous solution is 3:2, the pH value is 11.35, 130 g of tetrapropylammonium bromide, and 26.6 g of magnesium nitrate hexahydrate) into a pressurized reactor, and heat at 80℃ and 2.3 kg / cm². 2 The mixture was stirred under pressure for 1 hour, then washed, filtered, and dried to obtain the catalyst, designated A1. A photograph of the catalyst's morphology is shown below. Figure 1 As shown.
[0116] The crushing strength σ of catalyst A1 was measured and is listed in Table 1.
[0117] Example 2
[0118] (1) The crystallization mother liquor obtained in the preparation example was concentrated at 70-90℃ for several hours, with water added continuously during the process, to obtain 245 kg of molecular sieve mother liquor. After analysis and adjustment, the SiO2 content was 1.95%, the TPAOH content was 6.56%, the ethanol content was 12.42%, the water content was 78.52%, the KOH content was 0.50%, and other impurities were 0.05%.
[0119] (2) Under stirring conditions, the above 245 kg molecular sieve mother liquor, TEOS, TPAOH and water are mixed at room temperature for 4 h to obtain a colloidal mixture, wherein the mass ratio of SiO2 in the molecular sieve mother liquor to the mass ratio of organosilicon ester based on SiO2 is 0.08:1; and the molar ratio of SiO2:tetrapropylammonium hydroxide:KOH:water in the colloidal mixture is 1:0.15:0.04:25.
[0120] (3) The above colloidal mixture was fed into a 1M immersion chamber.3 In a stainless steel reactor, the alcohol-hydrothermal system was crystallized at 120°C for 2 days with a stirring rate of 45 rpm to obtain a molecular sieve slurry. The slurry was then filtered through a 50 nm membrane tube to obtain a crystallization mother liquor, which was bottled and reserved for use in the example. The molecular sieve slurry was then circulated and washed with 6-8 ml of washing water at a temperature of 40-60°C. 3 The washing water for the crystallized product is washed until the pH value reaches about 9.1-9.3. Then the slurry is concentrated and dried at 120℃ for 24 hours to obtain molecular sieve powder.
[0121] (4) The molecular sieve powder obtained in step (3) is pulverized in a pulverizer. 2 kg of the pulverized molecular sieve raw material (100-1000 mesh) is placed in a rotary molding machine. The rotary molding machine has a diameter of 1.2 m, a depth of 450 mm, an inclination angle of 50°, and a rotation speed of 30 rpm. 1.5 kg of alkaline silica sol with a SiO2 content of 30% by weight is added to it to obtain the first spherical particles with a diameter of approximately 0.2-0.8 mm.
[0122] Take another 210 kg of pulverized molecular sieve raw material (200-800 mesh) and mix it evenly with 40 kg of alkaline silica sol (SiO2 content 40% by weight). Add 45 kg of water, mix evenly, and pulverize again. Take particles smaller than 30 mesh and add 280 kg of the mixture at a uniform speed to the rotary forming machine containing the first spherical particles, completing the addition within 300 minutes. During the process, sieve the mixture multiple times using 12 mesh and 9 mesh sieves to obtain approximately 150 kg of second spherical particles with a diameter of 1.7-2.2 mm. The spherical particles smaller than 1.7 mm are returned to the rotary forming machine to continue growing.
[0123] The 100 kg of the second spherical particles obtained above were blown with air at 45°C, with trace amounts of water added several times during the process, and tightened for 2 hours. They were then dried at 120°C for 24 hours, and finally calcined at 550°C for 10 hours. The final calcined product had a molecular sieve content of ~92%.
[0124] (5) Add 90 kg of the above-mentioned roasted product and 900 kg of alkaline buffer solution (the alkaline buffer solution for the nitrogen-containing compound is a mixture of ammonia water and ammonium nitrate aqueous solution, wherein the content of ammonia water is 26 wt%, the content of ammonium nitrate in the ammonium nitrate aqueous solution is 7.5 wt%, the weight ratio of ammonia water to ammonium nitrate aqueous solution is 3:2, the pH value is 11.35, 130 g of tetrapropylammonium bromide, and 53 g of magnesium nitrate hexahydrate) into a pressurized reactor, and heat at 80℃ and 2.3 kg / cm². 2 The catalyst was stirred under pressure for 3 hours, then washed, filtered, and dried to obtain the catalyst, designated A2.
[0125] The crushing strength σ of catalyst A2 was measured and is listed in Table 1.
[0126] Example 3
[0127] The method is the same as in Example 1, except that the mass ratio of SiO2 in the molecular sieve mother liquor to the mass ratio of organosilicon esters based on SiO2 is 0.2:1, keeping the composition ratio of the colloidal mixture unchanged.
[0128] The catalyst was obtained and designated A3.
[0129] The crushing strength σ of catalyst A3 was measured and is listed in Table 1.
[0130] Example 4
[0131] The method of Example 1 was followed, except that the amount of KOH used was adjusted so that the composition of the colloidal mixture satisfied the molar ratio of SiO2:tetrapropylammonium hydroxide:KOH:water as 1:0.15:0.1:25. The resulting catalyst was designated A4.
[0132] The crushing strength σ of catalyst A4 was measured and is listed in Table 1.
[0133] Example 5
[0134] The method was followed in Example 1, except that the tetraethyl orthosilicate was sourced from Jiangxi Chenguang New Materials Co., Ltd., with a purity of 99.4 wt%, an ethanol content of 0.4 wt%, a platinum-cobalt color of 12 mg Pt-Co / L, and a Cl ion content of 65 ppm. The tetrapropylammonium hydroxide used was purchased from Tokyo Chemical Reagents, with a tetrapropylammonium hydroxide content of 25 wt%, a sodium ion content of 28.5 ppm, a bromide ion content of 1.2 wt%, a carbonate ion content of 0.2 wt%, an APHA color of 30, a potassium ion content of 1.1% wt%, an iron ion content of 38 ppm, an acetic acid content of 214 ppm, and formic acid and propionic acid contents of 26 ppm.
[0135] The catalyst was obtained and designated A5.
[0136] The measured crushing strength σ of catalyst A5 is listed in Table 1.
[0137] Example 6
[0138] The method was followed in Example 1, except that the crystallization temperature was 80°C and the crystallization time was 3 days. The resulting catalyst was designated A6. The yield of the molecular sieve was calculated to be 56%.
[0139] The crushing strength σ of catalyst A6 was measured and is listed in Table 1.
[0140] Example 7
[0141] The method is the same as in Example 1, except that the alkaline buffer solution is a mixture of ammonia, ammonium nitrate aqueous solution, 130g tetrapropylammonium bromide, and 1233g magnesium nitrate hexahydrate, wherein the content of ammonia is 26% by weight, the content of ammonium nitrate in the ammonium nitrate aqueous solution is 7.5% by weight, the weight ratio of ammonia to ammonium nitrate aqueous solution is 3:2, and the pH value of the alkaline buffer solution is 11.35.
[0142] A spherical catalyst was obtained, designated A7.
[0143] Example 8
[0144] The method is the same as in Example 1, except that the alkaline buffer solution containing nitrogen compounds is a mixture of ammonia, ammonium nitrate aqueous solution, 130g tetrapropylammonium bromide, and 2.6g magnesium nitrate hexahydrate, wherein the content of ammonia is 26% by weight, the content of ammonium nitrate in the ammonium nitrate aqueous solution is 7.5% by weight, the weight ratio of ammonia to ammonium nitrate aqueous solution is 3:2, and the pH value is 11.35.
[0145] A spherical catalyst was obtained, designated A8.
[0146] Example 9
[0147] The method is the same as in Example 1, except that in step (4), the molecular sieve powder obtained in step (3) is pulverized in a pulverizer. 220 kg of the pulverized molecular sieve raw material with a mesh size of 200-800 and 100 kg of alkaline silica sol with a SiO2 content of 30% by weight are placed in a rotary forming machine. The rotary forming machine has a rotary diameter of 1.2 m, a rotary depth of 450 mm, a rotary inclination angle of 50°, and a rotary speed of 30 rpm. The particles are sieved through 12-mesh and 9-mesh sieves to obtain spherical particles with a diameter of 1.7-2.2 mm.
[0148] The obtained catalyst was designated A9.
[0149] Comparative Example 1
[0150] The method of Example 1 is different except that, under stirring conditions, the molecular sieve mother liquor, TEOS and water are mixed at room temperature for 4 hours to obtain a colloidal mixture, wherein the mass ratio of SiO2 in the molecular sieve mother liquor to the mass ratio of organosilicate based on SiO2 is 0.32:1; and the molar ratio of SiO2:tetrapropylammonium hydroxide:water in the colloidal mixture is 1:0.25:25.
[0151] The obtained catalyst was designated DA1.
[0152] Experimental Example 1
[0153] This experimental example 1 is used to illustrate the catalytic reaction results of the molecular sieve catalysts prepared in the examples and comparative examples in the gas-phase Beckmann rearrangement reaction.
[0154] The catalysts prepared using the above examples and comparative examples were subjected to the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime under experimental conditions 1 and 2, respectively.
[0155] Experimental Condition 1: The reaction apparatus was a continuous flow fixed bed reactor at atmospheric pressure with an inner diameter of 5 mm. The catalyst loading was 0.469 g. The catalyst bed was topped with approximately 30 mm high, 30-mesh coarse quartz sand, and the bottom was filled with 50-mesh fine quartz sand. The catalyst particle size was 20-60 mesh. After being loaded into the reaction tube, the catalyst was pretreated for 1 hour at atmospheric pressure and 350°C under a nitrogen atmosphere. The concentration of the feedstock cyclohexanone oxime was 35 wt%, and the weight hourly space velocity (WHSV) was 16 h⁻¹. -1 The solvent was methanol, the reaction temperature was 380℃, the nitrogen flow rate was 45 ml / min, the reaction product was cooled by an ice-water mixture and then entered a collection bottle for gas-liquid separation, and the reaction time was 6 hours for product composition analysis.
[0156] Experimental conditions 2: The reaction apparatus was a continuous flow fixed bed reactor with an inner diameter of 28 mm; reaction pressure: 0.1 MPa; reaction temperature: 380℃; N2:cyclohexanone oxime (molar ratio) = 12:1; water in the methanol solution of cyclohexanone oxime was 1.2 wt%; vaporizer temperature control: 175℃; pipeline insulation: 185℃; catalyst loading: 30 g; bed height: 15.0 cm; cyclohexanone oxime concentration: 35 wt%; weight hourly space velocity (WHSV): 0.5 h⁻¹ -1 The solvent was anhydrous methanol, and the reaction time was 600 hours for product composition analysis.
[0157] The reaction products were quantitatively analyzed using an Agilent 6890 gas chromatograph (flame ionization detector, PEG20M capillary column, 50m column length). The vaporization chamber temperature was 250℃, the detection chamber temperature was 240℃, and the column temperature was programmed: 110℃ for 8 minutes, increased to 230℃ at a rate of 15℃ / min, and then held for 14 minutes. The reaction results are shown in Table 1.
[0158] The contents of the rearranged products of caprolactam and cyclohexenone after the reaction were calculated using the area normalization method, and the solvent was not included in the integration.
[0159] The above analysis yielded the molar percentages of cyclohexanone oxime and caprolactam in the reaction products. The conversion rate of cyclohexanone oxime and the total selectivity of caprolactam were then calculated using the following formulas. The results are shown in Table 1.
[0160] Cyclohexanone oxime conversion (mol%) = (100 - cyclohexanone oxime molar percentage in reaction product) / 100 × 100%;
[0161] Total selectivity of caprolactam (mol%) = (mol percentage of caprolactam in the reaction product) / (100 - mol percentage of cyclohexanone oxime in the reaction product) × 100%.
[0162] Table 1
[0163]
[0164] The results of the above examples and comparative examples show that the cyclohexanone oxime gas-phase Beckmann rearrangement catalyst prepared in the examples of the present invention has high crushing strength, high cyclohexanone oxime conversion and selectivity in the fixed-bed reaction process, and good stability.
[0165] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for preparing a gas-phase Beckmann rearrangement catalyst for cyclohexanone oxime, characterized in that, include: (1) Mix molecular sieve mother liquor, organosilicate, organic template agent and KOH to obtain colloidal mixture; The amounts of the molecular sieve mother liquor and the organosilicone ester are such that the mass ratio of SiO2 in the molecular sieve mother liquor to the mass ratio of organosilicone ester (calculated as SiO2) is 0.01-0.2:
1. The composition of the colloidal mixture satisfies that the molar ratio of SiO2, KOH, organic template agent, and water is 1:(0.01-0.1):(0.04-0.15):(15-45); (2) The colloidal mixture is subjected to a crystallization reaction; (3) The crystallization product obtained in step (2) is subjected to solid-liquid separation to obtain molecular sieve wet material and crystallization mother liquor; the molecular sieve wet material is dried to obtain molecular sieve raw powder; Optionally, the crystallization mother liquor may be concentrated, and then the process may return to step (1) to provide the molecular sieve mother liquor. (4) The molecular sieve powder is optionally mixed with a binder, and then rotated to form spherical particles; (5) The spherical particles are roasted and then contacted with an alkaline buffer solution containing ammonium salt, ammonia water, magnesium salt and bromide salt.
2. The preparation method according to claim 1, characterized in that, The composition of the colloidal mixture satisfies that the molar ratio of SiO2, KOH, organic template agent, and water is 1:(0.02-0.08):(0.08-0.2):(15-30); Preferably, the amounts of the molecular sieve mother liquor and the organosilicone ester are such that the mass ratio of SiO2 in the molecular sieve mother liquor to the mass ratio of organosilicone ester (calculated as SiO2) is 0.02-0.15:
1.
3. The preparation method according to claim 1 or 2, characterized in that, The silicon source is methyl orthosilicate and / or ethyl orthosilicate; Preferably, the Cl ion content in the organosilicon ester is not greater than 50 ppm; Preferably, the platinum-cobalt color of the organosilicon ester is not greater than 20 mg / L; Preferably, the purity of the organosilicon ester is not less than 98 wt%.
4. The preparation method according to any one of claims 1-3, characterized in that, The organic template agent is selected from quaternary ammonium base compounds, preferably tetrapropylammonium hydroxide and / or tetraethylammonium hydroxide, and more preferably tetrapropylammonium hydroxide; Preferably, the organic template agent contains less than 1.5 wt% bromide ions, and more preferably 0.5-1.5 wt%. Preferably, the iron ion content in the organic template agent is not greater than 10 ppm; Preferably, the organic template agent contains less than 500 ppm sodium ions, not more than 550 ppm free acid, less than 0.2 wt% carbonate ions, and an APHA color of no more than 100.
5. The preparation method according to any one of claims 1-4, characterized in that, In step (2), the temperature of the crystallization reaction is 95-150℃, preferably 100-150℃, and the time is 0.5-5 days, preferably 1-5 days.
6. The preparation method according to any one of claims 1-5, characterized in that, The molecular sieve mother liquor includes an organic template agent, silicon species, water, and optionally KOH; Preferably, the molecular sieve mother liquor contains 5-20 wt% organic template agent, 1-10 wt% silicon species (calculated as SiO2), 60-90 wt% water, and 0.1-1 wt% KOH, preferably 0.2-0.8 wt%. Preferably, the concentration conditions in step (3) include a temperature of 50-100℃, preferably 70-90℃.
7. The preparation method according to any one of claims 1-6, characterized in that, In step (4), the binder is a precursor of water or silicon dioxide, and the precursor of silicon dioxide is silica sol and / or silica, preferably silica sol; Preferably, the weight ratio of molecular sieve powder (dry basis) to binder (SiO2) is 1:(0.05-1), more preferably 1:(0.1-0.8).
8. The preparation method according to any one of claims 1-7, characterized in that, The spherical particles have a particle size of 0.1-3 mm, preferably 0.2-2.5 mm; Preferably, the rotational forming is performed in a rotary forming machine; Preferably, in the rotational molding process described in step (4), an additive is also introduced, which is selected from at least one of guar gum powder, graphite, activated carbon, paraffin wax, glycerin, citric acid, starch, polyethylene glycol, polyvinyl alcohol, nitric acid, hydrochloric acid, acetic acid, formic acid, ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide; Preferably, the amount of additive introduced is 1-5 wt%, based on the dry weight of the molecular sieve powder.
9. The preparation method according to any one of claims 1-8, characterized in that, The roasting conditions in step (5) include: a temperature of 200-600℃, preferably 250-550℃, and a time of 1-20h; Preferably, based on the total amount of the alkaline buffer solution, the content of magnesium salts (calculated as Mg) is 1-500 ppm, and the content of bromide salts (calculated as Br) is 1-500 ppm. Preferably, the pH of the alkaline buffer solution is 8.5-13.5; Preferably, the alkaline buffer solution comprises ammonia, an ammonium salt aqueous solution, a magnesium salt, and a bromide salt; Preferably, the weight ratio of ammonia water to ammonium salt aqueous solution is 1-3:1; Preferably, the concentration of the ammonia solution is 5-30 wt%. Preferably, the concentration of the ammonium salt aqueous solution is 0.5-10 wt%. Preferably, the amount of alkaline buffer solution used is 500-1500 parts by weight, more preferably 700-1200 parts by weight, relative to 100 parts by weight of calcined spherical particles. Preferably, the contact conditions include: a temperature of 50-120°C, more preferably 70-100°C; and a pressure of 0.5-10 kg / cm². 2 The preferred value is 1.5-4 kg / cm². 2 The time is 0.1-5 hours, preferably 1-3 hours.
10. A method for the gas-phase Beckmann rearrangement of cyclohexanone oxime, the method comprising: Under the conditions of the cyclohexanone oxime gas-phase Beckmann rearrangement reaction, in the presence of a solvent, cyclohexanone oxime is reacted with a catalyst, wherein the catalyst is a cyclohexanone oxime gas-phase Beckmann rearrangement reaction catalyst prepared by the preparation method according to any one of claims 1-9. Preferably, the contact takes place in a fixed-bed or moving-bed reactor.