CN112387297A

CN112387297A - Molecular sieve catalyst, preparation method and application thereof

Info

Publication number: CN112387297A
Application number: CN201910765060.5A
Authority: CN
Inventors: 王松林; 沈飞; 王韩; 徐锦龙; 李纵; 蒋肇彬; 胡小康; 张忠光; 唐席; 何怡漩; 马得佳
Original assignee: Zhejiang Henglan Technology Co Ltd
Current assignee: Zhejiang Henglan Technology Co Ltd
Priority date: 2019-08-19
Filing date: 2019-08-19
Publication date: 2021-02-23
Anticipated expiration: 2039-08-19
Also published as: CN112387297B

Abstract

The invention relates to the field of silicon molecular sieves, and discloses a molecular sieve catalyst, a preparation method and application thereof, wherein the preparation method of the molecular sieve catalyst comprises the following steps: 1) mixing a silicon source, organic amine, an organic template agent, a metal source, organic alcohol and water to obtain a colloid mixture; 2) crystallizing the colloid mixture by using a two-section temperature-variable alcohol-hydrothermal system, wherein the crystallization conditions of the two-section temperature-variable alcohol-hydrothermal system comprise: crystallizing at 40-70 deg.C for 0.5-5 days, and crystallizing at 80-130 deg.C for 0.5-5 days; 3) filtering, washing and drying the crystallized mother liquor obtained in the step 2) to obtain molecular sieve raw powder; 4) the molecular sieve raw powder is subjected to crushing, rolling forming, roasting and post-treatment of a nitrogen-containing compound, so that the obtained molecular sieve catalyst is good in catalytic performance, and when the molecular sieve catalyst is applied to caprolactam production, the conversion rate of cyclohexanone-oxime and the selectivity of caprolactam can be improved, and the service life of the catalyst is prolonged.

Description

Molecular sieve catalyst, preparation method and application thereof

Technical Field

The invention relates to the field of silicon molecular sieves, in particular to a molecular sieve catalyst and a preparation method and application thereof.

Background

Silicalite-1 molecular sieves, also known as all-silicon and pure-silicon molecular sieves, were first successfully synthesized in 1978 by E.M. Flanigen, et al, United states carbide, Inc., and belong to one of the members of the "Pentasil" family. The all-silicon molecular sieve is an aluminium-free molecular sieve with MFI topological structure, and is a molecular sieve with simplest composition in a ZSM-5 type structure molecular sieve family, the framework of the all-silicon molecular sieve only contains silicon atoms and oxygen atoms, and the basic structural unit is SiO₄A tetrahedron. The full-silicon molecular sieve with the MFI topological structure has rich microporous structures and regular and uniform three-dimensional pore canals, and has the crystal structure of a determined ZSM-5 type molecular sieve, higher internal specific surface area, good thermal stability, adsorption and desorption capacity and other performances. The development and application of the all-silicon molecular sieve in the fields of membrane adsorption separation, purification, catalytic materials and the like are receiving increasing attention.

The synthesis method of the all-silicon molecular sieve generally adopts a traditional organic raw material hydrothermal method, solid silicon oxide, silica sol, white carbon black or Tetraethoxysilane (TEOS) and the like are mostly selected as a silicon source, tetrapropylammonium hydroxide (TPAOH for short), low-carbon hydrocarbon quaternary ammonium salt or amine compound and the like are mostly selected as a template agent, and crystallization is carried out at the temperature of 170 ℃ for three days. Research groups such as united states carbide corporation (UCC), sweden Stety, and india p. They mainly apply the all-silicon molecular sieves in the research field of inorganic microporous materials.

The MFI structure all-silica molecular sieve disclosed in JP59164617A is prepared using tetraethyl orthosilicate (TEOS) as a silicon source and tetrapropylammonium hydroxide as a template. Researches in CATAL.REV. -SCI.ENG., 39(4), 395-424 (1997) show that the all-silicon molecular sieve synthesized by using tetraethoxysilane as a silicon source has higher BET total specific surface area and external surface area which can reach 400 m respectively²Per gram and 15-30 m²In grams, and the conversion of cyclohexanone oxime and the selectivity of caprolactam are directly proportional to the increase of the external surface area.

The synthesis process in CN102050464A comprises the following steps: (1) mixing ethyl orthosilicate and tetrapropylammonium hydroxide at room temperature, stirring, fully hydrolyzing for 3-5 hours, and adding water to form TPAOH/SiO with molar concentration₂＝0.2，H₂O/SiO₂A mixture of 20; (2) crystallizing the mixture in a closed reaction kettle at the autogenous pressure of 100 ℃ for 3 days, then washing, filtering and drying, and roasting the obtained all-silicon molecular sieve raw powder at the temperature of 550 ℃ for 6 hours, wherein the BET specific surface area of the sample is 439 meters²Per gram, external specific surface 60 m²Per gram; (3) placing a molecular sieve raw material with a certain mesh number and alkaline silica sol in a rotary disc type forming machine for rolling forming to obtain a spherical all-silicon molecular sieve with the molecular sieve content of 86%; (4) stirring the spherical all-silicon molecular sieve and the alkaline buffer solution in a pressure reaction kettle, and then washing, filtering and drying to obtain the catalyst with the crushing strength of 2.2 kg/particle.

U.S. patent application No. US4061724A discloses a method for synthesizing an all-silicon molecular sieve from SiO₂30 wt% hydrosol as silicon source, NaOH as alkali source and tetrapropylammonium bromide as template agent, and molecular sieve crystallizingThe pre-gel mixture molar composition was: 4.1Na₂O：50SiO₂：691H₂O: 1TPABr, crystallized at 200 ℃ for 3 days to obtain a catalyst with a crushing strength of 2.1 kg/pellet. When the molecular sieve obtained by the method is used for preparing caprolactam through cyclohexanone-oxime gas-phase Beckmann rearrangement reaction, the cyclohexanone-oxime conversion rate and caprolactam selectivity are high.

Because the MFI topological structure all-silicon molecular sieve has great difficulty in extrusion molding, tabletting molding, even rolling molding and the like, even after molding, the crushing strength of the catalyst is not ideal (<60N/cm or <1 kg/particle), and industrial application cannot be realized at all.

Caprolactam is a main raw material for producing three series products of nylon, industrial cord and nylon engineering plastics, and has high demand. The caprolactam is generally obtained by Beckmann rearrangement of cyclohexanone oxime. At present, the liquid phase rearrangement process using concentrated sulfuric acid or fuming sulfuric acid as a catalyst is generally adopted in industry. The caprolactam produced by the process accounts for about 90 percent of the total caprolactam production in the world, but the process needs to consume a large amount of sulfuric acid and ammonia water, and the production cost is higher because a byproduct of 1.3 to 1.8 tons of ammonium sulfate is produced every 1 ton of caprolactam. In addition, the use of sulfuric acid causes problems of equipment corrosion, environmental pollution and the like.

The gas phase Beckmann rearrangement reaction of cyclohexanone oxime on a solid acid catalyst is a new process for realizing the sulfur-free ammonification of caprolactam, has the problems of no equipment corrosion, no environmental pollution and the like, and greatly simplifies the separation and purification of products, so the gas phase Beckmann rearrangement reaction process of the sulfur-free ammonification is greatly concerned by the persons in the industry.

In order to develop a solid acid catalyst suitable for gas phase Beckmann rearrangement reaction, researchers at home and abroad have carried out a great deal of research on catalysts such as oxides (composite oxides), zeolite molecular sieves and the like, and the results show that most of the catalysts have certain activity, but the common defects are that the catalysts are easy to deactivate, the service life of the catalysts is short, and the industrial requirements cannot be met.

There are various solid acids as catalysts in the vapor phase beckmann rearrangement reaction, such as: silica-alumina catalysts, solid phosphoric acid catalysts, boric acid containing catalysts, high silicon/aluminum ratio MFI structure molecular sieve catalysts, and the like. Chinese patent application CN1256967A discloses a method for preparing a molecular sieve catalyst containing MFI structure for use in the reaction of converting cyclohexanone oxime into caprolactam. The basic starting point of the method is to use acid silica gel as a binder, and the method comprises the following specific steps: the silica oligomer prepared by acid hydrolysis of alkoxy silicon is mixed with water or alcohol-water dispersion of submicron particles of MFI structure molecular sieve with the pH value less than or equal to 5, and the mixture is emulsified, solidified, washed and roasted to prepare the gel microsphere.

At present, the fixed bed or moving bed process of cyclohexanone-oxime gas-phase Beckmann rearrangement reaction has the defects of short service life of a catalyst, difficulty in long-period continuous operation, high molar ratio of nitrogen and oxime, difficulty in heat transfer, poor technical economy and the like.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a preparation method of a molecular sieve catalyst, the molecular sieve catalyst prepared by the preparation method and application of the molecular sieve catalyst in cyclohexanone oxime gas phase Beckmann rearrangement reaction.

In a first aspect, the present invention provides a method for preparing a molecular sieve catalyst, the method comprising:

(1) mixing a silicon source, organic amine, an organic template agent, a metal source, organic alcohol and water to obtain a colloid mixture, wherein the molar ratio of the silicon source to the organic amine to the organic template agent to the organic alcohol to the water is 1: (0.05-0.5): (0.05-0.5): (4-20): (5-100), the mass ratio of the silicon source to the metal source is (10000-: 1, the silicon source is SiO₂The metal source is calculated by metal elements;

(2) crystallizing the colloid mixture by using a two-section temperature-variable alcohol-hydrothermal system, wherein the crystallization conditions of the two-section temperature-variable alcohol-hydrothermal system comprise: crystallizing at 40-70 deg.C for 0.5-5 days, and crystallizing at 80-130 deg.C for 0.5-5 days;

(3) filtering, washing and drying the crystallized mother liquor obtained in the step (2) to obtain molecular sieve raw powder;

(4) crushing, rolling and molding, roasting and post-treating the molecular sieve raw powder obtained in the step (3) with a nitrogen-containing compound;

the metal is selected from at least one of transition metals and group IIIA metals.

Preferably, the organic amine is tri-n-propylamine.

Preferably, the crystallization conditions of the two-stage temperature-variable alcohol-hydrothermal system comprise: crystallizing at 50-65 deg.C for 1-1.5 days, and crystallizing at 100-120 deg.C for 1.5-2 days.

The second aspect of the invention provides a molecular sieve catalyst prepared by the preparation method.

The third aspect of the invention provides the application of the molecular sieve catalyst in the cyclohexanone oxime gas phase Beckmann rearrangement reaction.

In the preparation method of the catalyst provided by the invention, alcohol and metal sources are additionally added in the synthesis process of the molecular sieve, organic amine and an organic template are adopted for matching use, and a two-stage temperature-variable alcohol-hydrothermal system is adopted for crystallization, so that trace metal elements can enter a molecular sieve framework, and the catalytic performance of the catalyst obtained by crushing, rolling forming treatment, roasting and post-treatment of a nitrogen-containing compound on the molecular sieve raw powder is good. The molecular sieve catalyst prepared by the invention contains trace metal elements, and the metal is preferably at least one selected from Al, Ag, Co, Ni, Cu, Zn, Mn, Pd, Pt, Cr, Fe, La, Au, Ru, Rh, Y, Ce, Pt, Rh, Ti, Zr, V, Mo and W. The adoption of the preferable metal elements is more beneficial to improving the conversion rate and the selectivity of the catalyst.

Compared with the prior art, the invention has the beneficial effects that: in the cyclohexanone-oxime gas-phase Beckmann rearrangement reaction, the existing all-silicon molecular sieve is used as a catalyst, the cyclohexanone-oxime conversion rate and caprolactam selectivity are high, the selectivity reaches 96 percent and 94.5 percent respectively in the 6 th hour of rapid evaluation, and basically reaches the limit, but the stability and the service life of the catalyst are difficult to guarantee along with the extension of reaction time. The preparation method of the invention is adopted to prepare the high-crystallinity fine-particle nearly neutral all-silicon molecular sieve, and the spherical catalyst obtained after rolling molding has good crushing strength, the method for preparing caprolactam by cyclohexanone-oxime gas-phase Beckmann rearrangement reaction with the spherical all-silicon molecular sieve as the catalyst in a moving bed or fixed bed reaction system can realize long-period and continuous production of caprolactam, under the condition of keeping caprolactam selectivity basically unchanged, the conversion rate of cyclohexanone oxime can be improved, the service life of the catalyst is prolonged, for example, the crushing strength of the catalyst provided by the invention can reach more than 2.5 kg/particle, when the catalyst is used in the cyclohexanone oxime gas phase Beckmann rearrangement reaction process, when the catalyst runs for 6 hours, the conversion rate of the cyclohexanone oxime can reach more than 97 percent, and the conversion rate of the cyclohexanone oxime can reach more than 99 percent when the operation is carried out for 600 hours.

Drawings

FIG. 1 is a photograph showing the morphology of the catalyst prepared in example 1 of the present invention.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The terms "first" and "second" are not intended to be limiting, but merely to distinguish between operations performed at different stages or materials added at different stages.

(1) mixing a silicon source, organic amine, an organic template agent, a metal source, organic alcohol and water to obtain a colloid mixture, wherein the molar ratio of the silicon source to the organic amine to the organic template agent to the organic alcohol to the water is 1: (0.05-0.5): (0.05-0.5):(4-20): (5-100), the mass ratio of the silicon source to the metal source is (10000-: 1, the silicon source is SiO₂The metal source is calculated by metal elements;

In the present invention, the molar ratio and the mass ratio refer to the molar ratio and the mass ratio of the amount of the material fed (charged) unless otherwise specified.

According to the method provided by the invention, preferably, the silicon source is an organic silicon source, more preferably an organic silicate, and for example, the silicon source can be represented by the general formula (OR)¹)₄Organosilicates of Si wherein R¹Is C1-C4 alkyl.

According to the method provided by the invention, most preferably, the silicon source is tetraethoxysilane and/or methyl orthosilicate.

According to the method provided by the invention, preferably, the organic amine is at least one selected from fatty amine compounds. Specifically, the general formula of the aliphatic amine compound can be (R)²)_k(NH_3-k)_n，R²Is alkyl having 1 to 6 carbon atoms, n ═ 1 or 2, k ═ 1, 2, or, 3; further preferably, the aliphatic amine compound may be selected from at least one of ethylamine, mono-n-propylamine, di-n-propylamine, tri-n-propylamine, n-butylamine, ethylenediamine and hexamethylenediamine, and most preferably is tri-n-propylamine.

According to the method provided by the invention, preferably, the organic template is selected from quaternary ammonium base compounds, and further preferably tetrapropylammonium hydroxide and/or tetraethylammonium hydroxide. The quaternary ammonium base compound may be an alkyl quaternary ammonium base compound having 1 to 4 carbon atoms, and tetrapropylammonium hydroxide and/or tetraethylammonium hydroxide is more preferable.

According to the method provided by the present invention, the metal may be selected from at least one of transition metals and group IIIA metals. Further, the transition metal is selected from at least one of group IB, group IIB, group IVB, group VB, group VIB, group VIIB and group VIII metals.

According to the method provided by the present invention, preferably, the metal is selected from at least one of Al, Ag, Co, Ni, Cu, Zn, Mn, Pd, Pt, Cr, Fe, La, Au, Ru, Rh, Y, Ce, Pt, Rh, Ti, Zr, V, Mo and W, further preferably, the metal is selected from at least one of Fe, Ni, Ti, Pd, Ce, Al, Cu, Zr, Pt and La, and most preferably at least one of Fe, Ti, Ce, Al, Zr and Pt. By adopting the preferred embodiment, the catalytic performance of the catalyst is improved.

According to the method provided by the invention, the metal source is a compound containing various metal elements capable of providing the metal, and preferably, the metal source is at least one selected from oxide, nitrate, chloride, sulfate, acetate and ester metal compounds of the metal. The ester metal compound may be ethyl titanate and/or butyl titanate.

According to the method provided by the invention, the metal source is preferably Fe (NO)₃)₃Tetrabutyl titanate, Ce (NO)₃)₄、Al(NO₃)₃、ZrOCl₂And H₂PtCl₆At least one of (1). The metal source may or may not contain crystal water, and the present invention is not particularly limited thereto.

According to the method provided by the invention, the organic alcohol can be at least one of monohydric alcohol and dihydric alcohol of C1-C4, and preferably, the organic alcohol is methanol and/or ethanol.

The present invention is not particularly limited to the specific embodiment of the mixing in step (1), as long as the colloidal mixture can be obtained.

According to a preferred mode of the present invention, the silicon source is tetraethoxysilane, and the organic alcohol is ethanol. In the research process, the inventor of the invention finds that the matching use of tetraethoxysilane as a silicon source and ethanol as organic alcohol is more beneficial to further improving the catalytic performance of the prepared catalyst. Further preferably, the mixing of step (1) comprises: firstly mixing ethanol, organic amine and an organic template agent, then adding a metal source and water, and then adding tetraethoxysilane; alternatively, the mixing of step (1) comprises: ethanol, organic amine and an organic template agent are mixed for the first time, then water and ethyl orthosilicate are added in sequence, and a metal source is added. The preferred embodiment is more beneficial to mixing of all materials and simultaneously more beneficial to exerting the matching effect of all materials.

According to a specific embodiment of the present invention, the first mixing is performed under stirring conditions, and the stirring time is not particularly limited as long as ethanol, organic amine and organic template are uniformly mixed. Specifically, the method may further include, after adding the metal source and water, stirring, and then adding the ethyl orthosilicate.

According to an embodiment of the present invention, the method may further include: after the addition of ethyl orthosilicate, stirring was performed to obtain the colloidal mixture. In the present invention, the stirring conditions are not particularly limited, and the stirring may be carried out at 10 to 50 ℃ for 0.5 to 10 hours, for example, so as to obtain the colloidal mixture.

According to another preferred embodiment of the present invention, the silicon source is methyl orthosilicate and the organic alcohol is methanol. In the research process, the inventor of the invention finds that the use of the methyl orthosilicate as a silicon source and the methanol as the organic alcohol is more beneficial to further improving the catalytic performance of the prepared catalyst. Preferably, the mixing of step (1) comprises: secondly, mixing methanol, organic amine and an organic template agent, then adding a metal source and water, and adding methyl orthosilicate; further preferably, the methyl orthosilicate is added in a plurality of portions, more preferably at a constant temperature of 10-30 ℃. By adopting the preferred embodiment, the hydrolysis speed of the methyl orthosilicate is more favorably controlled, and the catalytic performance of the prepared catalyst can be further improved.

The present invention is not particularly limited with respect to the specific operation of adding the methyl orthosilicate plural times, and specifically, the desired amount of the methyl orthosilicate may be divided into equal or unequal multiple portions (preferably 3 to 10 portions), and then the portions of the methyl orthosilicate may be added at intervals. The time interval is not particularly limited, and the time interval may be increased by adding a large amount of methyl orthosilicate, may be increased by appropriately increasing the time interval, may be decreased by adding a small amount of methyl orthosilicate, and may be shortened by appropriately decreasing the time interval, in consideration of the amount of methyl orthosilicate added each time. Preferably, the interval time can be 5-30min, and the interval times can be equal or different. In the embodiment of the present invention, the methyl orthosilicate is divided into 4 batches, and the interval time is 10min for an exemplary illustration, but the present invention is not limited thereto.

According to a preferred embodiment of the present invention, the silicon source, the organic amine, the organic template, the organic alcohol and the water are used in a molar ratio of 1: (0.05-0.3): (0.05-0.3): (4-15): (15-50), more preferably 1: (0.1-0.3): (0.1-0.2): (6-13): (20-40).

According to the invention, the mass ratio of the silicon source to the metal source is (12000) -140000): 1, more preferably (14000-50000): 1. by adopting the preferred embodiment, the proper amount of metal entering the framework of the molecular sieve is more beneficial to improving the catalytic performance of the catalyst.

According to the method provided by the invention, preferably, the crystallization conditions of the two-stage temperature-variable alcohol-hydrothermal system comprise: crystallizing at 50-65 deg.C for 1-1.5 days, and crystallizing at 100-120 deg.C for 1.5-2 days. The catalyst prepared by adopting the preferable hydrothermal system crystallization condition has better catalytic performance.

Specifically, the crystallization of the two-stage temperature-variable alcohol-hydrothermal system can be performed under autogenous pressure in a closed system, for example, in a closed reaction kettle.

According to a preferred embodiment of the invention, the method further comprises: and (3) carrying out alcohol removal on the crystallization mother liquor before the filtration in the step (3). Preferably, the alcohol-repelling conditions comprise: the temperature is 50-85 deg.C, and the time is 1-12 h.

According to the method provided by the present invention, the filtration and washing may be various filtration and washing methods conventionally used in the art, and the order of the two is not particularly limited. The detergent used in the washing process of the present invention is not particularly limited, and may be, for example, water. Preferably, the washing is carried out until the pH of the filtered wash water is 7.5 to 10, preferably 8 to 9.

According to the method provided by the invention, the drying conditions are selected in a wide range, for example, the drying conditions can comprise: the drying temperature is 80-150 ℃, and the drying time is 2-36 h; preferably, the drying temperature is 100-120 ℃, and the drying time is 10-30 hours.

According to the method provided by the invention, in the step (4), the molecular sieve raw powder is crushed and then mixed with the binder, and then the rolling forming is carried out. Preferably, the mass usage ratio of the solid matter obtained by crushing the molecular sieve raw powder to the binder is 1: (0.002-0.25), more preferably 1: (0.02-0.15).

According to the method provided by the invention, the binder is added for the purpose of making the powder particles mutually bonded during rotation, so that the strength of the formed product can be further improved.

The rolling forming can be one-step forming or step-by-step forming, and preferably step-by-step forming.

According to a preferred embodiment of the present invention, the roll forming of step (4) comprises:

a. selecting a first part of molecular sieve with the particle size of 100-1000 meshes from the solid substances obtained by crushing, mixing the first part of molecular sieve with a first binder, and carrying out first rolling molding to obtain first particles with the particle size of 0.1-0.8mm, wherein the mass ratio of the first part of molecular sieve to the first binder is 1: (0.2-1);

b. selecting a second part of molecular sieve with the particle size of 100-1000 meshes from the solid substances obtained by crushing, mixing the second part of molecular sieve, a second binder and the first particles, and carrying out second rolling molding to obtain second particles with the particle size of 1.3-2.5mm, wherein the mass ratio of the second part of molecular sieve to the second binder is 1: (0.001-0.5).

In the preferred embodiment, the selection of the molecular sieve with the particle size of 100-1000 meshes can be performed by sieving. The particle size refers to the maximum linear distance between any two different points on the particle, and when the particle is spherical, the particle size refers to its diameter.

Preferably, the first and second particles are each independently spherical.

According to the present invention, preferably, the second part of the molecular sieve and the second binder in step b may be added separately to be mixed with the first particles, or may be pre-mixed uniformly and then mixed with the first particles, and preferably, the second part of the molecular sieve and the second binder are pre-mixed uniformly and then mixed with the first particles.

Further preferably, the mixing the second portion of molecular sieve, the second binder and the first particles in step b comprises: mixing the second part of molecular sieve with a second binder, crushing, and mixing particles with the particle size of less than 30 meshes with the first particles. The use of this preferred embodiment is more advantageous in further increasing the crush strength of the catalyst.

According to the present invention, the weight ratio of the first part of molecular sieves to the second part of molecular sieves can be any ratio according to actual needs, and can also be adjusted at any time according to the condition of balling of the molecular sieves, and the present invention is not particularly limited.

According to the invention, the roll forming is preferably carried out in a rotary disc former. The first roll molding and the second roll molding may be performed in the same turntable molding machine, or may be performed in two turntable molding machines, preferably in the same turntable molding machine.

According to the method provided by the invention, the inventor of the invention discovers that the dwell time of the rolling ball forming of the rotary table, the inclination angle of the rotary table, the diameter D of the rotary table, the depth H of the rotary table and the rotating speed N of the rotary table can influence the rolling forming in the research process. Wherein the residence time refers to the average time from the time when a certain mesh number of molecular sieve raw materials are added into a rotary disc forming machine to the time when target particles are formed and are separated from the rotary disc forming machine, and can be usually 10-600 minutes, and preferably 30-180 minutes; the inclination angle of the turntable is an included angle between the turntable and the horizontal line, can be 40-55 degrees, preferably 45-50 degrees, when the inclination angle is smaller than 40 degrees, the molding state is poor, and the larger the inclination angle is, the smaller the size of the ball is; the relation between the diameter D of the rotary disc and the depth H of the rotary disc is preferably 0.1-0.25D; the rotational speed of the turntable is preferably 10 to 50rpm, more preferably 20 to 40 rpm.

According to the process provided by the invention, the throughput of the rotary disc former, in terms of the amount of catalyst produced per hour, may be from 20 to 100kg/h, for example 60 kg/h; the stock in the rotating disk is preferably 1/10-1/4 in terms of throughput. The material storage amount refers to the amount of micro and small ball catalysts which do not reach the qualified diameter in the rotating disc. The method is more beneficial to ensuring that the formed product has better mechanical strength and shape storability and avoiding the layering and peeling of product particles.

According to the invention, preferably, the binder is water and/or silica sol. The silica sol may be an acidic silica sol or an alkaline silica sol, and may be obtained commercially or prepared according to any one of the prior art, and more preferably, the silica sol is an alkaline silica sol.

Preferably, in the silica sol, SiO₂The content is 20-45 wt%.

Preferably, the silica sol has a sodium ion content of 10 to 300 ppm. It should be noted that sodium ions are basically washed away in the water washing step in the catalyst preparation process, and about 20-30ppm of sodium ions remain on the catalyst.

According to a preferred embodiment of the invention, the method further comprises: and after the rolling forming, before roasting, polishing the product obtained by the rolling forming. With this preferred embodiment, on the one hand, the roundness of the outer surface of the spherical catalyst can be increased and, on the other hand, the compressive strength of the catalyst can be further increased. The polishing treatment may be performed according to a means conventional in the art. For example, the product obtained by roll forming is blown at 20-50 ℃ (the moisture can be removed), the micro water of the product is supplemented for a plurality of times (for example, 3-10 times) in the blowing process (the catalyst surface can be wetted, the small-range deformation is easy, the roundness of the ball is improved), and then the product is tightened (the blowing process is carried out without adding water, and generally the process can be carried out for 1-4 hours).

According to a particular embodiment of the invention, the method further comprises drying the rollformed product before said firing. The drying conditions may include: the drying temperature is 80-150 ℃, and the drying time is 2-36 h; preferably, the drying temperature is 100-120 ℃, and the drying time is 10-30 hours.

The calcination in step (4) of the present invention can be performed in a conventional furnace, for example, a heating shuttle furnace, and preferably, the calcination in step (4) is performed under the conditions comprising: the temperature is 400-600 ℃, and the time is 1-24h, and more preferably, the temperature is 400-550 ℃, and the time is 1-10 h.

According to a preferred embodiment of the invention, the post-treatment of the nitrogen-containing compound comprises: the roasted product obtained by roasting is contacted with an alkaline buffer solution containing a nitrogen compound, and then is dried. It is more advantageous to use this preferred embodiment to provide the catalytic properties of the catalyst produced.

According to the present invention, preferably, the basic buffer solution of the nitrogen-containing compound contains an ammonium salt and a base, and the solvent thereof may be water. The nitrogen-containing compound may be an ammonium salt, for example ammonium nitrate and/or ammonium acetate. The base may be selected from at least one of aqueous ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide, and is preferably aqueous ammonia.

According to a preferred embodiment of the invention, the ammonium salt is present in an amount of 0.5 to 20% by weight; the alkali content is 5-30 wt%. In the examples of the present invention, the content of ammonium salt is 7.5 wt% and the content of alkali is 26 wt%, which are given as examples, but the present invention is not limited thereto.

Preferably, the pH value of the alkaline buffer solution of the nitrogen-containing compound is 8.5 to 13.5, more preferably 9 to 12, and still more preferably 11 to 11.5.

Preferably, the weight ratio of the roasted product to the alkaline buffer solution containing the nitrogen compound is 1: (5-15).

Preferably, the conditions of the contacting include: the temperature is 50-120 deg.C, and the pressure is 0.5-5kg/cm²The time is 10-300 min. Further preferably, the contacting is performed under stirring conditions. The stirring speed is not particularly limited in the present invention, and can be appropriately selected by those skilled in the art according to the actual situation.

According to the method provided by the invention, the process of contacting with the alkaline buffer solution containing the nitrogen compound can be repeated. The number of repetitions is not particularly limited in the present invention, and may be determined depending on the catalyst performance, and may be repeated, for example, 1 to 3 times.

The conditions for drying in the post-treatment of the nitrogen-containing compound are not particularly limited in the present invention, and the drying may be carried out according to the conventional technical means in the art, as long as the moisture is removed, and the drying method includes, but is not limited to, natural drying, heat drying, and forced air drying, wherein the drying temperature may be 100 ℃ to 120 ℃, and the drying time may be 10 to 24 hours.

According to the present invention, in particular, the method may further include: and before the drying, sequentially filtering and washing substances obtained after the roasted product is contacted with an alkaline buffer solution containing a nitrogen compound. The detergent used in the washing process of the present invention is not particularly limited, and may be, for example, water.

The second aspect of the present invention provides a molecular sieve catalyst having a crush strength σ of > 2.0 kg/pellet, preferably > 2.5 kg/pellet, more preferably 2.5 to 2.8 kg/pellet, obtainable by the above-described process.

The third aspect of the invention provides the application of the molecular sieve catalyst in the cyclohexanone oxime gas phase Beckmann rearrangement reaction. The molecular sieve catalyst provided by the invention is used for cyclohexanone oxime gas phase Beckmann rearrangement reaction, can improve the conversion rate of cyclohexanone oxime and the selectivity of caprolactam, can prolong the service life of the catalyst, and improves the economy of a new gas phase rearrangement process technology.

According to the application provided by the invention, the cyclohexanone oxime can be contacted with the catalyst in the presence of a solvent to carry out a gas-phase Beckmann rearrangement reaction. When the molecular sieve catalyst is applied to cyclohexanone-oxime gas-phase Beckmann rearrangement reaction, the cyclohexanone-oxime conversion rate and caprolactam selectivity are high, long-period and continuous production of caprolactam can be realized, and caprolactam selectivity and yield are higher than those of the existing all-silicon molecular sieve catalyst. And the total amount of the by-products is reduced, so that the energy consumption for separating the products is reduced, and the technical economy is effectively improved.

Preferably, the molar ratio of the solvent to the cyclohexanone oxime is (2-10): 1. the solvent may be selected from fatty alcohols of C1-C6, preferably at least one of methanol, ethanol and n-propanol.

Preferably, the gas phase Beckmann rearrangement reaction is carried out in the presence of nitrogen gas, the molar ratio of the nitrogen gas to the cyclohexanone oxime is (10-80): 1, more preferably (40-60): 1.

preferably, the conditions of the gas phase beckmann rearrangement reaction include: the weight space velocity (WHSV) of the cyclohexanone oxime is 0.1-20 h^-1Preferably 0.5 to 16 hours^-1(ii) a The reaction temperature is 300-500 ℃, preferably 350-400 ℃, and more preferably 360-390 ℃; the reaction pressure is 0.1-0.5MPa in terms of gauge pressure.

The present invention is described in detail below by way of examples.

The content of metal elements was measured using an ICP inductively coupled plasma atomic emission spectrometer 7000DV, from PE (perkin elmer) in usa, under the following test conditions: dissolving the molecular sieve by HF acid or aqua regia to completely dissolve silicon oxide and metal oxide in the sample, and measuring the content of metal ions in the aqueous solution.

The crushing strength σ was measured on a particle strength measuring instrument model QCY-602 (manufactured by soda industry research institute of the department of original chemical industry) according to the RIPP25-90 method in petrochemical analysis (Yankeeding et al, scientific Press, 1990).

The roll forming in the following examples was carried out in a rotary disc forming machine, model BY-1200, a coater (sugar coater) made BY Tiantai pharmaceutical machinery, Taizhou.

Example 1

(1) To 3m³870kg of 95 wt% ethanol (EtOH), 58.5kg of tri-n-propylamine and 180kg of 22.5 wt% aqueous tetrapropylammonium hydroxide (TPAOH) solution were charged into a stainless steel reaction vessel, respectively, and stirred, and 540kg of water and 37.2g of Fe (NO) were further charged into the reaction vessel₃)₃·9H₂And O, continuously stirring, finally adding 416kg of tetraethoxysilane, and fully stirring for 6 hours at normal temperature (25 ℃) to form a colloid mixture, wherein the silicon source: (C)₃H₈)₃N：TPAOH：EtOH：H₂The molar ratio of the used O is 1: 0.2: 0.1: 9: 20, silicon source and Fe³⁺The dosage mass ratio of 23600: 1, wherein the silicon source is SiO₂And (6) counting.

(2) The above colloid mixture is crystallized in alcohol-water heating system at 60 deg.c for 1 day and then in alcohol-water heating system at 100 deg.c for 2 days.

(3) Cooling the reaction kettle, opening a kettle cover, performing ethanol removal treatment at the temperature of 75 ℃ for 6 hours, then performing membrane filtration by adopting a 50nm six-tube membrane and washing by adopting water at the temperature of 50 ℃ until the pH value of the washing water reaches or approaches 9.0, and drying the washed molecular sieve slurry at the temperature of 120 ℃ for 20 hours to obtain the molecular sieve raw powder required by the rolling forming of the embodiment.

And (3) roasting a small amount of the obtained molecular sieve raw powder at 550 ℃ for 6 hours to obtain the molecular sieve with the iron ion content of 42 mu g/g. The molecular sieve has uniform crystal grain size of 0.15-0.25 μm.

(4) And (4) crushing the molecular sieve raw powder obtained in the step (3) in a crusher, putting 2kg of crushed molecular sieve raw material with 100-1000 meshes in a turntable forming machine, wherein the diameter of a turntable of the turntable forming machine is 1.2m, the depth of the turntable is 450mm, the inclination angle of the turntable is determined to be 50 degrees, and the rotating speed of the turntable is set to be 30 rpm. 1.5kg of deionized water was sprayed thereto to obtain first spherical particles having a diameter of about 0.2 to 0.8 mm.

Taking 220kg of 200-mesh 800-mesh crushed molecular sieve raw material and 100kg of SiO₂Mixing 30 wt% alkaline silica sol, pulverizing, and taking small piecesAdding 300kg of the granules with 30 meshes into the rotary table forming machine with the first spherical granules at a constant speed, and finishing the adding within 240 min. Wherein, the second spherical particles with the diameter of 1.7-2.2mm are obtained by sieving with 12-mesh and 9-mesh sieves for a plurality of times in the midway, about 160kg of the spherical particles with the diameter less than 1.7mm are poured back into the turntable forming machine to continue growing.

The 90kg of the second spherical particles obtained above was blown at 45 ℃ and its trace water was replenished several times midway, tightened for 2 hours, dried at 120 ℃ for 24 hours, and then calcined at 550 ℃ for 10 hours. Finally obtaining a roasted product with the molecular sieve content of 86 percent.

(5) Adding 90kg of the above roasted product and 900kg of an alkaline buffer solution (the alkaline buffer solution is a mixed solution of ammonia water and an ammonium nitrate aqueous solution, wherein the content of the ammonia water is 26 wt%, the content of the ammonium nitrate in the ammonium nitrate aqueous solution is 7.5 wt%, the weight ratio of the ammonia water to the ammonium nitrate aqueous solution is 3: 2, and the pH value of the alkaline buffer solution is 11.35) into a reaction kettle with pressure, and adding the mixture into the reaction kettle at 80 ℃ and 2.3kg/cm²Stirred under pressure for 1 hour, then washed, filtered and dried to obtain catalyst No. a 1. The morphology of the catalyst is shown in figure 1.

The crush strength σ of the catalyst A1 was measured and is shown in Table 1.

Comparative example 1

The process of example 1 was followed except that, in the step (2), the conditions for the crystallization of the alcohol-hydrothermal system were: crystallizing the alcohol-water heating system for 3 days at 100 ℃. Catalyst D1 was obtained.

Comparative example 2

The procedure of example 1 was followed except that no ethanol was added during the catalyst preparation, i.e. no ethanol was added in step (1). Catalyst D2 was obtained.

Comparative example 3

The procedure is as in example 1, except that NO Fe (NO) is added during the preparation of the catalyst₃)₃·9H₂And O. Catalyst D3 was obtained.

Comparative example 4

The procedure is as in example 1, except that tri-n-propylamine is not added during the catalyst preparation. Catalyst D4 was obtained.

Comparative example 5

This comparative example illustrates the synthesis of an all-silica molecular sieve according to the method of chinese patent application CN 1338427A.

278kg of ethyl orthosilicate was poured at room temperature 25 ℃ into 2m³Stirring for 30 minutes in a stainless steel reaction kettle, adding 240kg of 22.5 wt% tetrapropyl ammonium hydroxide aqueous solution into ethyl orthosilicate, stirring and hydrolyzing for 5 hours at room temperature and 25 ℃, adding 296kg of water and 534kg of ethanol, stirring uniformly to obtain sol, wherein the chemical composition of the mixed sol is H₂O/SiO₂＝20，EtOH/SiO₂＝12.7，TPAOH/SiO₂Crystallizing at 110 deg.C for 2 days, filtering, washing until pH value of washing water reaches or approaches 9.0, drying the concentrated slurry at 120 deg.C for 20 hr to obtain the molecular sieve powder, and pulverizing.

Taking 220kg of 200-mesh 800-mesh crushed molecular sieve raw material and 100kg of SiO₂The alkaline silica sol containing 30 wt% was placed in a rotary disk forming machine to be roll-formed, the rotary disk of the forming machine was rotated by the rotary disk to have a diameter of 1.2m, a depth of the rotary disk was 450mm, an inclination angle of the rotary disk was determined to be 50 °, a rotation speed of the rotary disk was set to 30rpm, spherical particles having a diameter of about 1.7 to 2.2mm were obtained, and then dried at 120 ℃ for 24 hours and calcined at 550 ℃ for 10 hours to obtain a calcined product.

Adding 90kg of the above roasted product and 900kg of an alkaline buffer solution (the alkaline buffer solution is a mixed solution of ammonia water and an ammonium nitrate aqueous solution, wherein the content of the ammonia water is 26 wt%, the content of the ammonium nitrate in the ammonium nitrate aqueous solution is 7.5 wt%, the weight ratio of the ammonia water to the ammonium nitrate aqueous solution is 3: 2, and the pH value of the alkaline buffer solution is 11.35) into a reaction kettle with pressure (KCF-2 type magnetic stirring autoclave, Nicoti Hippon area Keli automatic control Equipment research institute), and carrying out reaction at 80 ℃ and 2.3kg/cm²Stirred under pressure for 1 hour, then washed, filtered and dried to obtain catalyst No. D5. The catalyst crush strengths σ are listed in table 1.

Example 2

(1) To 3m³580kg of 95 wt% ethanol, 87.6kg of tri-n-propylamine and 580kg of a solvent were added to a stainless steel reactor, respectively180kg of 22.5 wt% tetrapropylammonium hydroxide aqueous solution, stirring, continuously adding 900kg of water into the reaction kettle, stirring, finally adding 416kg of ethyl orthosilicate, fully mixing, finally adding 35.6g of tetrabutyl titanate, and fully stirring for 6 hours at normal temperature (25 ℃) to form a colloidal mixture with the pH value of 13.39, wherein the silicon source: (C)₃H₈)₃N：TPAOH：EtOH：H₂The molar ratio of the used O is 1: 0.3: 0.1: 6: 30, silicon source and Ti⁴⁺The dosage mass ratio of 23600: 1, wherein the silicon source is SiO₂And (6) counting.

(2) The above colloid mixture is crystallized in alcohol-water heating system at 50 deg.C for 1 day, and then crystallized in alcohol-water heating system at 100 deg.C for 2 days.

A small amount of the obtained molecular sieve raw powder is roasted for 6 hours at the temperature of 550 ℃, and the titanium ion content in the obtained molecular sieve is measured to be 41.8 mu g/g. The molecular sieve has uniform crystal grain size of 0.15-0.25 μm.

(4) And (4) crushing the molecular sieve raw powder obtained in the step (3) in a crusher, putting 2kg of crushed molecular sieve raw material with 100-1000 meshes in a turntable forming machine, wherein the diameter of a turntable of the turntable forming machine is 1.2m, the depth of the turntable is 450mm, the inclination angle of the turntable is determined to be 50 degrees, and the rotating speed of the turntable is set to be 30 rpm. 1.4kg of deionized water was sprayed thereto to obtain first spherical particles having a diameter of about 0.2 to 0.8 mm.

Another 200kg of 200-800 mesh crushed molecular sieve raw material and 40kg of SiO₂Mixing 30 wt% of alkaline silica sol, adding 55kg of water, uniformly mixing, pulverizing again, adding particles smaller than 30 meshes into the first spherical particle-containing rotary table forming machine at constant speed, and finishing the adding within 300 min. Wherein the granules are sieved with 12-mesh and 9-mesh sieves to obtain second spherical granules with diameter of 1.7-2.2mm, about 150kg, and smallPouring the 1.7mm spherical particles back to the rotary disc forming machine for continuous growth.

100kg of the second spherical particles obtained above was blown at 45 ℃ and its trace water was replenished in the course of several times, tightened for 2 hours, dried at 120 ℃ for 24 hours, and then calcined at 550 ℃ for 10 hours. Finally obtaining a roasted product with the molecular sieve content of 93 percent.

(5) Adding 90kg of the above roasted product and 900kg of an alkaline buffer solution (the alkaline buffer solution is a mixed solution of ammonia water and an ammonium nitrate aqueous solution, wherein the content of the ammonia water is 26 wt%, the content of the ammonium nitrate in the ammonium nitrate aqueous solution is 7.5 wt%, the weight ratio of the ammonia water to the ammonium nitrate aqueous solution is 3: 2, and the pH value of the alkaline buffer solution is 11.35) into a reaction kettle with pressure, and adding the mixture into the reaction kettle at 100 ℃ and 2.8kg/cm²Stirred under pressure for 1 hour, then washed, filtered and dried to obtain catalyst No. a 2.

The crush strength σ of the catalyst A2 was measured and is shown in Table 1.

Example 3

(1) To 3m³870kg of 95 wt% ethanol, 58.4kg of tri-n-propylamine and 180kg of 22.5 wt% aqueous tetrapropylammonium hydroxide solution were added to a stainless steel reaction vessel, respectively, and stirred, and 540kg of water and 19.2g of Ce (NO) were further added to the reaction vessel₃)₄·7H₂And O, continuously stirring, finally adding 416kg of tetraethoxysilane, fully mixing, and fully stirring for 6 hours at normal temperature (25 ℃) to form a colloidal mixture with the pH value of 12.49, wherein the silicon source: (C)₃H₈)₃N：TPAOH：EtOH：H₂The molar ratio of the used O is 1: 0.20: 0.10: 9: 20, silicon source and Ce⁴⁺The dosage mass ratio of 23500: 1, wherein the silicon source is SiO₂And (6) counting.

(2) The above colloid mixture is crystallized in alcohol-water heating system at 65 deg.c for 1 day and then in alcohol-water heating system at 120 deg.c for 2 days.

Roasting a small amount of the obtained molecular sieve raw powder at 550 ℃ for 6 hours to obtain the molecular sieve with cerium ion content of 42 mu g/g, uniform grain size and particle size of 0.15-0.25 mu m.

(4) And (4) crushing the molecular sieve raw powder obtained in the step (3) in a crusher, putting 2kg of crushed molecular sieve raw material with 100-1000 meshes in a turntable forming machine, wherein the diameter of a turntable of the forming machine is 1.2m, the depth of the turntable is 450mm, the inclination angle of the turntable is determined to be 50 degrees, and the rotating speed of the turntable is set to be 30 rpm. Adding SiO thereto₂1.5kg of an alkaline silica sol in an amount of 30% by weight, to give first spherical particles having a diameter of about 0.2 to 0.8 mm.

Another 200kg of the molecular sieve raw material after 800-mesh crushing and 50kg of SiO₂Uniformly mixing 40 wt% of alkaline silica sol, adding 45kg of water, uniformly mixing, pulverizing again, adding particles smaller than 30 meshes into the first spherical particle-containing rotary table forming machine at constant speed, and finishing the adding within 300 min. Wherein, the second spherical particles with the diameter of 1.7-2.2mm are obtained by sieving with 12-mesh and 9-mesh sieves for a plurality of times in the midway, about 150kg of the spherical particles with the diameter less than 1.7mm are poured back into the turntable forming machine to continue growing.

100kg of the second spherical particles obtained above was blown at 45 ℃ and its trace water was replenished in the course of several times, tightened for 2 hours, dried at 120 ℃ for 24 hours, and then calcined at 550 ℃ for 10 hours. Finally obtaining a roasted product with the molecular sieve content of 89.5 percent.

(5) Adding 90kg of the above roasted product and 900kg of an alkaline buffer solution (the alkaline buffer solution is a mixed solution of ammonia water and an ammonium nitrate aqueous solution, wherein the content of the ammonia water is 26 wt%, the content of the ammonium nitrate in the ammonium nitrate aqueous solution is 7.5 wt%, the weight ratio of the ammonia water to the ammonium nitrate aqueous solution is 3: 2, and the pH value of the alkaline buffer solution is 11.35) into a reaction kettle with pressure, and adding the mixture into the reaction kettle at 80 ℃ and 2.3kg/cm²Stirred under pressure for 3 hours, then washed, filtered and dried to obtain catalyst No. a 3.

The crush strength σ of the catalyst A3 was measured and is shown in Table 1.

Example 4

(1) 575kg of methanol (MeOH), 58.5kg of tri-n-propylamine and 180kg of 22.5% aqueous tetrapropylammonium hydroxide solution were added to 3m, respectively, at a constant temperature of 25 deg.C³The mixture was stirred in a stainless steel reactor, and 580kg of water and 69.6g of Al (NO) were continuously added to the reactor₃)₃·9H₂And O, stirring for 30 minutes, dividing into four batches, wherein each batch is separated by 15 minutes, adding 304kg of methyl orthosilicate into a reaction kettle, stirring for 60 minutes, then continuously stirring and hydrolyzing for 2 hours at the constant temperature of 25 ℃, and uniformly stirring to form a colloidal mixture with the pH value of 12.58, wherein the silicon source: (C)₃H₈)₃N：TPAOH：MeOH：H₂The molar ratio of the used O is 1: 0.20: 0.10: 9: 20, silicon source and Al³⁺The dosage mass ratio of 23600: 1, wherein the silicon source is SiO₂And (6) counting.

(3) Cooling the reaction kettle, opening a kettle cover, performing methanol removal treatment at the temperature of 75 ℃ for 6 hours, then performing membrane filtration by adopting a 50nm six-tube membrane and washing by adopting water at the temperature of 50 ℃ until the pH value of the washing water reaches or approaches 9.0, and drying the washed molecular sieve slurry at the temperature of 120 ℃ for 20 hours to obtain the molecular sieve raw powder required by the rolling forming of the embodiment.

And (3) roasting a small amount of the obtained molecular sieve raw powder at 550 ℃ for 6 hours to obtain the molecular sieve with the aluminum ion content of 41 mu g/g. The molecular sieve has uniform crystal grain size of 0.15-0.25 μm.

(4) And (4) crushing the molecular sieve raw powder obtained in the step (3) in a crusher, putting 10kg of crushed molecular sieve raw material with 200-500 meshes in a turntable forming machine, wherein the diameter of a turntable of the turntable rolling forming machine is 1.2m, the depth of the turntable is 450mm, the inclination angle of the turntable is determined to be 50 degrees, and the rotating speed of the turntable is set to be 30 rpm. About 5.8kg of deionized water was sprayed thereto to obtain first spherical particles having a diameter of about 0.2 to 0.8 mm.

And adding 200kg of the crushed molecular sieve raw material with the particle size of 200-800 meshes into the turntable forming machine with the first spherical particles at a constant speed within 300min after uniformly mixing with 95kg of deionized water. Wherein, the second spherical particles with the diameter of 1.7-2.2mm are obtained by sieving the mixture for a plurality of times by 12 meshes and 9 meshes in the midway, about 140kg of the spherical particles with the diameter less than 1.7mm are poured back into the rotary table forming machine to grow continuously.

Blowing 90kg of the second spherical particles obtained above at 45 ℃, supplementing a trace amount of water to a rolling forming machine for many times in the middle, tightening for 2 hours, drying at 120 ℃ for 24 hours, and then roasting at 550 ℃ for 10 hours. Finally obtaining a roasted product with the molecular sieve content of 100 percent.

(5) Adding 90kg of the above roasted product and 900kg of an alkaline buffer solution (the alkaline buffer solution is a mixed solution of ammonia water and an ammonium nitrate aqueous solution, wherein the content of the ammonia water is 26 wt%, the content of the ammonium nitrate in the ammonium nitrate aqueous solution is 7.5 wt%, the weight ratio of the ammonia water to the ammonium nitrate aqueous solution is 3: 2, and the pH value of the alkaline buffer solution is 11.35) into a reaction kettle with pressure, and adding the mixture into the reaction kettle at 80 ℃ and 2.3kg/cm²Stirred under pressure for 1 hour, then washed, filtered and dried to obtain catalyst No. a 4.

The crush strength σ of the catalyst A4 was measured and is shown in Table 1.

Example 5

(1) 384kg of methanol, 87.5kg of tri-n-propylamine and 180kg of 22.5% aqueous tetrapropylammonium hydroxide solution were added to 3m, respectively, at a constant temperature of 25 deg.C³In a stainless steel reaction kettle, 900kg of water and 17.6g of ZrOCl are added₂·8H₂Pouring O into a reaction kettle, stirring for 10 minutes, dividing into four batches, and separating each batch for 15 minutes, adding 304.6kg of methyl orthosilicate into the mixed solution, stirring for 60 minutes, and then continuing stirring and hydrolyzing at the constant temperature of 25 ℃ for 2 hours to form a colloidal mixture with the pH value of 12.44, wherein the silicon source: (C)₃H₈)₃N：TPAOH：MeOH：H₂The molar ratio of the used O is 1: 0.30: 0.10: 6: 30, silicon source and Zr⁴⁺The dosage mass ratio of 23600: 1, wherein the silicon source is SiO₂And (6) counting.

And (3) roasting a small amount of the obtained molecular sieve raw powder at 550 ℃ for 6 hours to obtain the molecular sieve with the zirconium ion content of 41 mu g/g. The molecular sieve has uniform crystal grain size of 0.15-0.25 μm.

(4) And (3) crushing the molecular sieve raw powder obtained in the step (3) in a crusher, putting 2kg of the crushed molecular sieve raw material with 200-500 meshes in a turntable forming machine, wherein the diameter of a turntable of the turntable rolling forming machine is 1.2m, the depth of the turntable is 450mm, the inclination angle of the turntable is determined to be 50 degrees, and the rotating speed of the turntable is set to be 30 rpm. 1.5kg of deionized water was sprayed thereto to obtain first spherical particles having a diameter of about 0.2 to 0.8 mm.

Taking 220kg of 200-mesh 800-mesh crushed molecular sieve raw material and 100kg of SiO₂Mixing 30 wt% of alkaline silica sol, pulverizing again, adding particles smaller than 30 mesh into the first spherical particle rotary table forming machine at constant speed of 300kg, and adding within 240 min. Wherein, the second spherical particles with the diameter of 1.7-2.2mm are obtained by sieving with 12-mesh and 9-mesh sieves for a plurality of times in the midway, about 160kg of the spherical particles with the diameter less than 1.7mm are poured back into the turntable forming machine to continue growing.

Blowing 90kg of the second spherical particles obtained above at 45 ℃, supplementing a trace amount of water to a rolling forming machine for many times in the middle, tightening for 2 hours, drying at 120 ℃ for 24 hours, and then roasting at 530 ℃ for 10 hours. Finally obtaining a roasted product with the molecular sieve content of 86 percent.

(5) Adding 90kg of the above roasted product and 900kg of an alkaline buffer solution (the alkaline buffer solution is a mixed solution of ammonia water and an ammonium nitrate aqueous solution, wherein the content of the ammonia water is 26 wt%, the content of the ammonium nitrate in the ammonium nitrate aqueous solution is 7.5 wt%, the weight ratio of the ammonia water to the ammonium nitrate aqueous solution is 3: 2, and the pH value of the alkaline buffer solution is 11.35) into a reaction kettle with pressure, and adding the mixture into the reaction kettle at 80 ℃ and 2.3kg/cm²Under pressureStirred for 1 hour, then washed, filtered and dried to obtain catalyst No. A5.

The crush strength σ of the catalyst A5 was measured and is shown in Table 1.

Example 6

(1) 575kg of methanol, 43.75kg of tri-n-propylamine and 270kg of 22.5% aqueous tetrapropylammonium hydroxide solution were added to 3m at a constant temperature of 25 ℃ respectively³In the stainless steel reaction kettle, 510kg of water and 13.2g H are added₂PtCl₆·6H₂Pouring O into a reaction kettle, stirring for 10 minutes, dividing into four batches, and separating each batch for 15 minutes, adding 304.4kg of methyl orthosilicate into the mixed solution, stirring for 60 minutes, then continuously stirring at the constant temperature of 25 ℃ for hydrolysis for 2 hours to form sol, and uniformly stirring to form a colloidal mixture with the pH value of 12.82, wherein the silicon source: (C)₃H₈)₃N：TPAOH：MeOH：H₂The molar ratio of the used O is 1: 0.15: 0.15: 9: 20, silicon source and Pt⁴⁺The dosage mass ratio of 23600: 1, wherein the silicon source is SiO₂And (6) counting.

And (3) roasting a small amount of the obtained molecular sieve raw powder at 550 ℃ for 6 hours to obtain the molecular sieve with the platinum ion content of 41 mu g/g. The molecular sieve has uniform crystal grain size of 0.15-0.25 μm.

Blowing 90kg of the second spherical particles obtained above at 45 ℃, supplementing a trace amount of water to a rolling forming machine for many times in the middle, tightening for 2 hours, drying at 120 ℃ for 24 hours, and then roasting at 550 ℃ for 10 hours. Finally obtaining a roasted product with the molecular sieve content of 86 percent.

(5) Adding 90kg of the above roasted product and 900kg of an alkaline buffer solution (the alkaline buffer solution is a mixed solution of ammonia water and an ammonium nitrate aqueous solution, wherein the content of the ammonia water is 26 wt%, the content of the ammonium nitrate in the ammonium nitrate aqueous solution is 7.5 wt%, the weight ratio of the ammonia water to the ammonium nitrate aqueous solution is 3: 2, and the pH value of the alkaline buffer solution is 11.35) into a reaction kettle with pressure, and adding the mixture into the reaction kettle at 100 ℃ and 2.8kg/cm²Stirred under pressure for 1 hour, then washed, filtered and dried to obtain catalyst No. a 6.

The crush strength σ of the catalyst A6 was measured and is shown in Table 1.

Example 7

The procedure is as in example 1, except that tri-n-propylamine is replaced with the same molar amount of ethylenediamine. Catalyst No. a7 was obtained.

The crush strength of catalyst A7 was measured and is shown in Table 1.

Example 8

The procedure is as in example 3, except that Ce (NO) is added₃)₄·7H₂Substitution of O for ZrOCl₂·8H₂O, and Si source and Zr⁴⁺The dosage mass ratio of 40000: 1, the zirconium ion content of the obtained molecular sieve is 24.2 mu g/g. Catalyst No. A8 was obtained. The crush strength of catalyst A8 was measured and is shown in Table 1.

Example 9

The procedure is as in example 3, except that Ce (NO) is added₃)₄·7H₂Replacing O with an aluminum source (SB powder, aluminum oxide mass content of 70%, Ti)⁴⁺Ion content 5 mug/g), and silicon source and Al³⁺The dosage mass ratio of the components is 15000: 1, the content of aluminum ions in the obtained molecular sieve is 64.1 mu g/g. Catalyst No. a9 was obtained. The crush strength of catalyst A9 was measured and is shown in Table 1.

Example 10

The method according to example 1, except that step (4) comprises: crushing the molecular sieve raw powder obtained in the step (3) in a crusher, and taking 220kg of the crushed molecular sieve raw material with 200-mesh and 800-mesh and 100kg of SiO₂The alkaline silica sol with a content of 30 wt% was placed in a turntable forming machine having a turntable diameter of 1.2m, a turntable depth of 450mm, a turntable inclination angle of 50 ° and a turntable rotation speed of 30 rpm. Sieving with 12 mesh and 9 mesh sieve to obtain second spherical granule with diameter of 1.7-2.2 mm. Catalyst No. a10 was obtained. The crush strength of catalyst A10 was measured and is shown in Table 1.

Test example 1

This test example 1 is intended to illustrate the results of the catalytic reaction of the molecular sieve catalysts prepared in examples 1 to 10 and comparative examples 1 to 5 in the gas phase beckmann rearrangement reaction.

The vapor phase Beckmann rearrangement reaction of cyclohexanone oxime was carried out under test condition 1 and test condition 2 using catalysts A1-A10 and D1-D5, respectively.

Test conditions 1: the reaction device is a constant-pressure continuous flow fixed bed, the inner diameter of the reactor is 5mm, the loading amount of the catalyst is 0.469 g, coarse quartz sand with the height of about 30mm and the size of 30 meshes is filled on the catalyst bed layer, and fine quartz sand with the size of 50 meshes is filled under the catalyst bed layer. The granularity of the catalyst is 20-60 meshes. The catalyst was packed in a reaction tube and then pretreated at 350 ℃ for 1 hour under normal pressure in a nitrogen atmosphere. The concentration of the raw material cyclohexanone-oxime is 35 wt%, and the weight space velocity (WHSV) is 16h^-1The solvent is methanol, the reaction temperature is 380 ℃, the nitrogen flow is 45ml/min, the reaction product is cooled by an ice-water mixture and then enters a collecting bottle for gas-liquid separation, and the reaction time is 6 hoursAnd analyzing the composition of the product.

Test conditions 2: the reaction apparatus was a continuous flow fixed bed, the reactor internal diameter was 28 mm, the reaction pressure: 0.1 MPa; reaction temperature: 380 ℃; n is a radical of₂: cyclohexanone oxime (molar ratio) 12: 1; the mass percent of water in the methanol solution of cyclohexanone oxime is 1.2 wt%; the temperature of the vaporizer is controlled to be 175 ℃; keeping the temperature of the pipeline at 185 ℃; the loading of the catalyst is 30 g; height of bed layer: 15.0 cm; the concentration of the raw material cyclohexanone-oxime is 35 wt%, and the weight space velocity (WHSV) is 0.5h^-1The solvent is absolute methanol, and the reaction time is 600 hours for product composition analysis.

The reaction product was quantitatively analyzed by Agilent 6890 gas chromatography (hydrogen flame ion detector, PEG20M capillary chromatographic column, column length 50m), the vaporization chamber temperature was 250 deg.C, the detection chamber temperature was 240 deg.C, the column temperature was programmed to increase, the temperature was maintained at 110 deg.C for 8 minutes, 15 deg.C/min was increased to 230 deg.C, and the temperature was maintained for 14 minutes. The reaction results are shown in Table 1.

The content of rearrangement products of caprolactam and cyclohexenone after the reaction is calculated by adopting an area normalization method, and the solvent does not participate in the integral.

The molar percentage of cyclohexanone oxime in the reaction product and the molar percentage of caprolactam in the reaction product are obtained through the analysis, and the conversion rate of cyclohexanone oxime and the total selectivity of caprolactam are calculated according to the following formula. The results are shown in Table 1.

Cyclohexanone oxime conversion (mol%) (100-cyclohexanone oxime mol% in reaction product)/100 × 100%

Total caprolactam selectivity (mol%) × 100% for caprolactam mol% (caprolactam mol%) in the reaction product/(100-cyclohexanone oxime mol% in the reaction product)

TABLE 1

As can be seen from Table 1, the molecular sieve catalyst prepared by the method of the invention has higher crushing strength which can reach 2.9 kg/particle at most, and therefore, the molecular sieve catalyst can be used for a fixed bed or moving bed process for preparing caprolactam by cyclohexanone oxime gas phase Beckmann rearrangement. In addition, the catalyst A1-A10 prepared by the invention has higher cyclohexanone oxime conversion rate, the conversion rate of the cyclohexanone oxime after 6 hours of reaction can reach more than 97%, and compared with the all-silicon molecular sieve catalyst synthesized by the method in the prior art CN1338427A, the conversion rate of the cyclohexanone oxime is improved by 1%. In addition, after the catalysts synthesized in examples 1-10 are used for reaction for 600 hours, the conversion rate of cyclohexanone oxime can still reach more than 99 percent, and the service life of the catalyst is longer. Under the same test conditions, the all-silicon molecular sieves of comparative examples 1 to 5 are used as catalysts for the cyclohexanone oxime gas phase Beckmann rearrangement reaction, the catalysts are deactivated after 600 hours, and the conversion rate of the cyclohexanone oxime is obviously lower than that of the catalysts provided by the invention.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A method of preparing a molecular sieve catalyst, the method comprising:

2. The preparation method according to claim 1, wherein the silicon source is an organosilicate, preferably tetraethoxysilane and/or methyl orthosilicate;

preferably, the organic amine is selected from at least one of aliphatic amine compounds, and is further preferably at least one of ethylamine, mono-n-propylamine, di-n-propylamine, tri-n-propylamine, n-butylamine, ethylenediamine and hexamethylenediamine;

preferably, the organic template is selected from quaternary ammonium base compounds, further preferably tetrapropylammonium hydroxide and/or tetraethylammonium hydroxide;

preferably, the transition metal is selected from at least one of group IB, group IIB, group IVB, group VB, group VIB, group VIIB and group VIII metals;

preferably, the metal is selected from at least one of Al, Ag, Co, Ni, Cu, Zn, Mn, Pd, Pt, Cr, Fe, La, Au, Ru, Rh, Y, Ce, Pt, Rh, Ti, Zr, V, Mo and W, more preferably at least one of Fe, Ni, Ti, Pd, Ce, Al, Cu, Zr, Pt and La;

preferably, the metal source is selected from at least one of oxides, nitrates, chlorides, sulfates, acetates and ester metal compounds of the metal;

preferably, the organic alcohol is methanol and/or ethanol.

3. The preparation method according to claim 1, wherein the silicon source is tetraethoxysilane and the organic alcohol is ethanol;

preferably, the mixing of step (1) comprises: firstly mixing ethanol, organic amine and an organic template agent, then adding a metal source and water, and then adding tetraethoxysilane; alternatively, the mixing of step (1) comprises: ethanol, organic amine and an organic template agent are mixed for the first time, then water and ethyl orthosilicate are added in sequence, and a metal source is added.

4. The preparation method according to claim 1, wherein the silicon source is methyl orthosilicate, and the organic alcohol is methanol;

preferably, the mixing of step (1) comprises: secondly, mixing methanol, organic amine and an organic template agent, then adding a metal source and water, and adding methyl orthosilicate;

further preferably, the methyl orthosilicate is added by multiple additions.

5. The preparation method according to claim 1, wherein the silicon source, the organic amine, the organic template, the organic alcohol and the water are used in a molar ratio of 1: (0.05-0.3): (0.05-0.3): (4-15): (15-50);

preferably, the mass ratio of the silicon source to the metal source is (12000) -140000): 1.

6. the preparation method of claim 1, wherein the crystallization conditions of the two-stage temperature-variable alcohol-hydrothermal system comprise: crystallizing at 50-65 deg.C for 1-1.5 days, and crystallizing at 100-120 deg.C for 1.5-2 days.

7. The preparation method according to claim 1, wherein, in the step (4), the raw molecular sieve powder is pulverized and then mixed with a binder, and the roll forming is performed;

preferably, the roll forming of step (4) includes:

8. The production method according to claim 7, wherein the binder is water and/or silica sol;

preferably, the mixing the second portion of molecular sieve, the second binder and the first particles in step b comprises: mixing the second part of molecular sieve with a second binder, crushing, and mixing particles with the particle size of less than 30 meshes with the first particles.

9. The production method according to any one of claims 1 to 8, wherein the roll forming is performed in a rotary disc forming machine;

preferably, the operating conditions of the carousel-forming machine comprise: the residence time is 10-600min, the inclination angle of the rotary table is 40-55 degrees, the relation between the diameter D of the rotary table and the depth H of the rotary table is 0.1-0.25D, and the rotating speed of the rotary table is 10-50 rpm.

10. The production method according to any one of claims 1 to 9, wherein the conditions for the calcination in step (4) include: the temperature is 400-600 ℃, preferably 400-550 ℃, and the time is 1-24h, preferably 1-10 h.

11. The production method according to any one of claims 1 to 10, wherein the nitrogen-containing compound post-treatment comprises:

contacting a roasted product obtained by roasting with an alkaline buffer solution containing a nitrogen compound, and then drying;

preferably, the alkaline buffer solution containing the nitrogen-containing compound contains ammonium salt and alkali, the content of the ammonium salt is 0.5-20 wt%, the content of the alkali is 5-30 wt%, and the pH value of the alkaline buffer solution containing the nitrogen-containing compound is 8.5-13.5;

preferably, the weight ratio of the roasted product to the alkaline buffer solution containing the nitrogen compound is 1: (5-15);

preferably, the contact temperature is 50-120 ℃ and the contact pressure is 0.5-5kg/cm²The contact time is 10-300 min.

12. A molecular sieve catalyst prepared by the preparation process of any one of claims 1 to 11;

preferably, the crush strength σ of the catalyst is > 2.0 kg/particle.

13. Use of the molecular sieve catalyst prepared by the preparation method according to any one of claims 1 to 11 or the molecular sieve catalyst according to claim 12 in a cyclohexanone oxime gas phase beckmann rearrangement reaction.