CN109847787B

CN109847787B - Rotational molding preparation method and application of microsphere all-silicon molecular sieve catalyst with MFI topological structure and containing trace rare earth ions

Info

Publication number: CN109847787B
Application number: CN201910065841.3A
Authority: CN
Inventors: 王松林; 沈飞; 王韩
Original assignee: Zhejiang Henglan Technology Co Ltd
Current assignee: Zhejiang Hengyi Petrochemical Research Institute Co Ltd
Priority date: 2019-01-23
Filing date: 2019-01-23
Publication date: 2021-10-26
Anticipated expiration: 2039-01-23
Also published as: CN109847787A

Abstract

The invention relates to the field of all-silicon molecular sieves, and discloses a rotational molding preparation method and application of a microsphere all-silicon molecular sieve catalyst with an MFI topological structure and containing trace rare earth ions, wherein the preparation method comprises the following steps: a. mixing a silicon source, a rare earth ion source, an organic template agent and water to obtain a colloid mixture; b. performing segmented hydrothermal crystallization on the colloid mixture, performing membrane filtration and washing on the obtained crystallization product, and drying to obtain an all-silicon molecular sieve containing trace rare earth ions; c. crushing the all-silicon molecular sieve, mixing with a binder, and rotationally molding to obtain a microsphere all-silicon molecular sieve catalyst; d. roasting, contacting with alkaline buffer solution containing nitrogen compound, washing, filtering and drying to obtain the finished product. The catalyst has low abrasion index, and can improve the technical economy of a new process when used for carrying out the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime in a fluidized bed process.

Description

Rotational molding preparation method and application of microsphere all-silicon molecular sieve catalyst with MFI topological structure and containing trace rare earth ions

Technical Field

The invention relates to the field of all-silicon molecular sieves, in particular to a rotational molding preparation method and application of a microsphere all-silicon molecular sieve catalyst with an MFI topological structure and containing trace rare earth ions.

Background

Silicalite-1 molecular sieves (abbreviated as all-silica-1 molecular sieves) were first successfully synthesized in 1978 by E.M. Flanigen et al, UCC, and belong to the last member of the "Pentasil" family. The all-silicon-1 molecular sieve is an aluminium-free molecular sieve with MFI topological structure, is a molecular sieve with simplest composition in a ZSM-5 type structure molecular sieve family, and has a framework only containing silicon atoms and oxygen atoms, and a basic structural unit of SiO₄A tetrahedron. The all-silicon-1 molecular sieve has rich microporous structure and regular and uniform three-dimensional fine pore channels, has the crystal structure of the determined ZSM-5 type molecular sieve, higher internal specific surface area and good thermal stabilityQualitative, adsorption and desorption capacity and the like. The all-silicon-1 molecular sieve can be used as an application material of a chemical sensor, a photoelectric acoustic wave device and a membrane reactor. In particular, the molecular sieve membrane is applied to gas permeable membranes, pervaporation membranes, sensing material membranes, optical material membranes and the like. Therefore, the development and application of the all-silicon-1 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-1 molecular sieve generally adopts a traditional organic raw material hydrothermal method, a silicon source can be selected from solid silicon oxide, silica sol, white carbon black, Tetraethoxysilane (TEOS) and the like, a template agent mostly adopts tetrapropylammonium hydroxide (TPAOH), low-carbon hydrocarbon quaternary ammonium salt or a mixture of the tetrapropylammonium hydroxide and the lower-carbon hydrocarbon quaternary ammonium salt, an amine compound and the like, and the crystallization is carried out for three days at the temperature of 170 ℃. Research groups such as united states carbide corporation (UCC), sweden Stety, and india p. They mainly apply the all-silicon-1 molecular sieve to the research field of inorganic microporous materials.

The MFI structure all-silica molecular sieve disclosed in JP59164617 is prepared by using tetraethyl orthosilicate (TEOS) as a silicon source and tetrapropylammonium hydroxide as a template agent. 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 all-silicon molecular sieves disclosed in chinese patents CN00123576.1 and zl00123577.x include two synthesis methods, one of which is: mixing ethyl orthosilicate and tetrapropylammonium hydroxide at room temperature, stirring, hydrolyzing, heating to 70-75 ℃, adding water, carrying out hydrothermal crystallization on the mixture, mixing with organic base, and carrying out sealing treatment, wherein alcohol is driven by raising the temperature in the synthesis process. The second method is that the tetraethoxysilane and the tetrapropylammonium hydroxide are mixed and stirred at room temperature, after hydrolysis, water and ethanol are added to form the mixture with the molar concentration of TPAOH/SiO₂＝0.05-0.5，EtOH/SiO₂＝4-30，H₂O/SiO₂2-100 in admixture; carrying out hydrothermal crystallization on the mixture; the roasted product and the organic alkali are mixed uniformly and then are subjected to closed treatment, a large amount of ethanol is added in the synthesis process, the cost of raw materials is high, the COD discharge amount is large, and the solid content of the molecular sieve in the synthesis kettle is low.

The synthesis process of the all-silicon molecular sieve disclosed in the Chinese patent CN 102050464A 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＝0.05-0.5，EtOH/SiO₂＝4，H₂O/SiO₂A mixture of 5 to 100; (2) the mixture is crystallized for 0.5 to 10 days at the autogenous pressure of 80 to 120 ℃ in a closed reaction kettle, and then is washed, filtered and dried, and is roasted for 1 to 10 hours at the temperature of 400 ℃ and 600 ℃.

ZL200910210326.6 discloses a method for synthesizing an all-silicon molecular sieve, which takes ethyl silicate as a silicon source and tetrapropylammonium hydroxide as an alkali source and a template agent, and the gel mixture before the crystallization of the molecular sieve comprises the following components in molar composition: SiO 2₂： 0.05～0.5TPAOH：4EtOH：5～100H₂And O, crystallizing at the temperature of 80-120 ℃ for 1-3 days. 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 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 (less than 60N/cm or less than 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 the demand is always more vigorous. 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% 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 high because a byproduct of 1.3-1.8 tons of ammonium sulfate is generated every 1 ton of caprolactam is produced. 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.

The process which makes the production more economical and meets the requirement of greenization is a gas phase Beckmann rearrangement method. The method for preparing caprolactam by carrying out gas-phase Beckmann rearrangement on cyclohexanone oxime does not use sulfuric acid and ammonia water, and has the advantages of no equipment corrosion, no environmental pollution, no byproduct ammonium sulfate and the like. There are various solid acids as catalysts in the vapor phase beckmann rearrangement reaction, such as: silica alumina catalyst as used in british patent GB881,927; solid phosphoric acid catalysts as used in british patent GB881,956; a catalyst containing boric acid as used in British patent GB1,178,057; the MFI structure molecular sieve catalyst with high silicon/aluminum ratio adopted in the Chinese patent CN1269360A, and the like. So far, the fluidized bed process is suitable for gas phase Beckmann rearrangement reaction, and the microspheres are suitable for serving as a catalyst of the process.

Spray forming is the most common method for preparing microspherical catalysts, is simple and practical, and is widely used in the field of petrochemical industry. Spray forming belongs to a combined technological process of spraying and drying. The raw material slurry is sprayed into extremely fine fog-like liquid drops under the action of an atomizer, then the fog-like liquid drops are uniformly mixed by hot air, and then heat exchange and mass exchange are rapidly carried out to evaporate water, so that the granular product is obtained. Such as microspheres.

Spray forming is divided into three types, namely pressure type, centrifugal disc type and air flow type, and has the characteristics of simple process flow, convenient production, strong productivity, easy adjustment and control of the diameter, the particle size distribution, the moisture content and the like of catalyst particles. However, the thermal efficiency of spray forming is low, the pump delivery is difficult for sticky paste materials, spray forming is carried out after dilution, and meanwhile, the requirement on gas-solid separation is high, and the equipment is huge. The microspheres are of a moderate strength due to the spraying action of the catalyst.

In EP576,295 it is proposed to prepare microspheres from molecular sieves by spray drying without the addition of any binder and then to subject the microspheres to a heat treatment in water to increase the mechanical strength of the microspheres, so that the microspherical catalyst can be used in a fluidized bed reactor for the conversion of cyclohexanone oxime to caprolactam. Obviously, such strength is not satisfactory for industrial applications.

Chinese patent 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 liquid 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. The catalyst is suitable for use in a fluidized bed reactor.

U.S. Pat. No. 4,485985 discloses a method for preparing titanium-containing silicon molecular sieve catalyst by using basic silica gel as binder. The alkaline silica gel is prepared by hydrolyzing tetraalkyl silicate, preferably tetraalkyl orthosilicate in tetraalkyl ammonium hydroxide aqueous solution at room temperature to 200 ℃ for 0.2-10 hours, wherein the pH of the alkaline silica gel is more than or equal to 10. The prepared catalyst is a microsphere catalyst suitable for a fluidized bed reactor.

The cyclohexanone oxime gas phase Beckmann rearrangement reaction fixed bed or moving bed process has the defects of short catalyst life, difficult continuous operation in a long period, high nitrogen oxime molar ratio, difficult heat transfer and poor technical economy. The fluidized bed process is relatively suitable for cyclohexanone oxime gas phase Beckmann rearrangement reaction.

So far, no relevant documents and patents are available for rolling (rotating) and forming the all-silicon molecular sieve containing extremely small amount of rare earth ions into a microspherical shape and applying the all-silicon molecular sieve to cyclohexanone oxime gas phase Beckmann rearrangement reaction.

Disclosure of Invention

In order to solve the technical problems, the invention provides a rotational molding preparation method and application of a microspherical MFI topological structure all-silicon molecular sieve catalyst containing trace rare earth ions.

The specific technical scheme of the invention is as follows: a rotational molding preparation method of a microsphere all-silicon molecular sieve catalyst with an MFI topological structure and containing trace rare earth ions comprises the following steps:

a. mixing a silicon source, a rare earth ion source, an organic template agent and water to obtain a colloid mixture; wherein SiO in the colloid mixture₂The mol ratio of the organic template agent to the water is 1 to (0.05-0.50) to (5-100); the mass ratio of the silicon source to the rare earth ions is (10000-) -200000: 1 in terms of silicon dioxide.

b. And (2) performing hydrothermal crystallization on the colloid mixture at 50-60 ℃ for 0.5-3 days, performing hydrothermal crystallization at 80-120 ℃ for 0.5-3 days, performing membrane filtration on the obtained crystallized product, washing until the pH value is 8-10, and drying to obtain the all-silicon molecular sieve with the MFI topological structure and containing trace rare earth ions.

c. Crushing the full-silicon molecular sieve containing trace rare earth ions and having the MFI topological structure into 100-0000 meshes, mixing the crushed full-silicon molecular sieve with a binder, and rotationally forming the mixture into a microsphere full-silicon molecular sieve catalyst with the MFI topological structure and the particle size of 20-400 mu m by using a rotary forming machine; the rotating speed of the rotating forming machine is 30-70rpm, and the inclination angle of the rotating disc is 0-30 degrees.

d. And c, roasting the microspherical all-silicon molecular sieve catalyst with the MFI topological structure obtained in the step c, contacting the roasted microspherical all-silicon molecular sieve catalyst with the MFI topological structure with an alkaline buffer solution containing a nitrogen compound, washing, filtering and drying to obtain a finished product.

Different cations have different degrees of difficulty in entering the molecular sieve framework, for example, Si, Al and the like can easily enter the molecular sieve framework, transition metals can hardly enter the molecular sieve framework, and the difficulty of noble metals is higher. And the atomic and ionic radii of the rare earth elements are larger than those of the noble metals, which means that the rare earth elements are more difficult to enter the molecular sieve framework than the noble metals. The invention adopts a specific technical means of segmentation and temperature-changing crystallization, solves the problem that rare earth ions are difficult to enter a molecular sieve framework, and enables extremely trace rare earth ions to enter the all-silicon-1 molecular sieve framework. The invention successfully prepares the MFI topological structure silicon molecular sieve containing trace rare earth ions for the first time in the world. Compared with other elements such as noble metals, the rare earth has lower cost, and particularly, the cost advantage is more obvious under the condition of high rare earth reserves in China.

Preferably, the obtained catalyst comprises 70-95 wt% of an all-silica molecular sieve with an MFI topological structure and containing trace rare earth ions and 5-30wt% of a binder on a dry basis weight basis; the particle size of the catalyst is 40-200 mu m, and the abrasion index K is less than 5.

Preferably, the BET specific surface area of the all-silicon molecular sieve with MFI topological structure containing trace rare earth ions is 400-500m²The weight ratio of silicon dioxide to rare earth ions in the total-silicon molecular sieve with MFI topological structure is (10000-200000) to 1.

Preferably, the obtained catalyst comprises 80-90 wt% of all-silicon molecular sieve and 10-20 wt% of binder based on the dry weight.

Preferably, the binder is silica sol, the sodium ion content of the silica sol is 10-500ppm, and SiO is₂The content is 20-45 wt%.

Preferably, in step a, the rare earth ion is selected from Ce³⁺、Ce⁴⁺、La³⁺At least one of; the rare earth ion source is at least one of nitrate, chlorate, acetate and carbonate containing the rare earth ions.

Preferably, the source of rare earth ions is selected from La (NO)₃)₃·6H₂O、La(OAc)₃·5H₂O、LaCl₃·7H₂O、 La₂(CO₃)₃·xH₂O、Ce(NO₃)₃·6H₂O、Ce(NO₃)₄·7H₂O、Ce(OAc)₃·5H₂O、Ce(SO₄)₂·2H₂O、 CeCl₃·7H₂At least one of O.

Preferably, in step a, the silicon source is at least one selected from the group consisting of silica gel, silica sol and organosilicate; the organic template agent is selected from at least one of fatty amine compounds, alcohol amine compounds and quaternary ammonium base compounds; wherein the general formula of the aliphatic amine compound is R²(NH₂)_n，R²Is an alkyl group having 1 to 6 carbon atoms, n is an integer between 1 and 3, and the alcohol amine compound has a general formula of (HOR)³)_mN，R³Is alkyl with 1-4 carbon atoms, m is an integer between 1-3, and the alkyl quaternary ammonium base compound has 1-4 carbon atoms.

Preferably, the organosilicate has the formula (OR)¹)₄Si, wherein R¹Is an alkyl group of 1 to 4 carbon atoms.

Preferably, the organic silicate is methyl orthosilicate and/or ethyl orthosilicate; the organic template agent is an alkyl quaternary amine alkali compound and/or a fatty amine compound; the alkyl quaternary ammonium alkali compound is tetraethyl ammonium hydroxide and/or tetrapropyl ammonium hydroxide; the aliphatic amine compound is at least one of ethylamine, n-butylamine, n-propylamine, ethylenediamine and hexamethylenediamine.

Preferably, in step a, the colloidal mixture further comprises a lower alcohol, and the lower alcohol is mixed with SiO₂The molar ratio of the lower alcohol to the lower alcohol is 1 to (4-15), and the lower alcohol is ethanol.

Preferably, in step c, the rotational molding is performed with the addition of an additive selected from at least one of sesbania powder, graphite, activated carbon, paraffin, stearic acid, glycerin, oxalic acid, tartaric acid, citric acid, starch, polyethylene glycol, polyvinyl alcohol, polyethylene oxide, polyallylamine, cellulose methyl ether, cellulose, polymeric alcohol, nitric acid, hydrochloric acid, acetic acid, formic acid, ammonia water, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide; the dosage of the additive is 1-5 wt% of the dry weight of the molecular sieve.

Preferably, in step d, the alkaline buffer solution containing the nitrogen-containing compound contains ammonium salt and alkali, the content of the ammonium salt is 0.5-20wt%, the content of the alkali is 5-30wt%, and the pH value of the alkaline buffer solution containing the nitrogen-containing compound is 8.5-13.5.

Preferably, the ammonium salt is at least one of ammonium carbonate, ammonium fluoride, ammonium chloride, ammonium acetate and ammonium nitrate; the alkali is at least one of ammonia water, tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide and tetrapropyl ammonium hydroxide.

Preferably, the ammonium salt is ammonium acetate and/or ammonium nitrate; the alkali is ammonia water.

Preferably, in the step d, the weight ratio of the calcined molecular sieve to the alkaline buffer solution containing the nitrogen compound is 1 to (5-15) on a dry basis, the contact temperature is 50-120 ℃, and the contact pressure is 0.5-5kg/cm²The contact time is 10 to 300 minutes, and it is determined whether or not the alkaline buffer solution post-treatment of the nitrogen-containing compound is repeated several times depending on the performance of the catalyst.

Preferably, in step d, the roasting conditions are as follows: the temperature is 200 ℃ and 600 ℃ and the time is 1-20 hours.

The invention also discloses a preparation method of caprolactam, which comprises the following steps: the cyclohexanone oxime is contacted with the catalyst prepared by the method in the presence of a solvent to carry out gas-phase Beckmann rearrangement reaction.

Preferably, the molar ratio of the solvent to the cyclohexanone oxime is (2-10) to 1; the solvent is selected from fatty alcohol of C1-C6, preferably methanol and/or ethanol.

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

Preferably, the conditions under which the gas phase beckmann rearrangement reaction is carried out are: the weight space velocity of the cyclohexanone-oxime is 0.1-20 hours^-1The reaction temperature is 300-500 ℃, and the reaction pressure is 0.1-0.5 MPa.

Preferably, the method further comprises mixing the cyclohexanone oxime with water in a molar ratio of 1 to (0.01-2.5), and then contacting the mixture with the catalyst in the presence of the solvent to perform the gas-phase Beckmann rearrangement reaction.

The service life of the catalyst can be prolonged by adding a small amount of water into the cyclohexanone oxime.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, rare earth ions with extremely small amount are added in the synthesis process of the all-silicon molecular sieve, so that the performance of the all-silicon molecular sieve can be effectively changed, and then the all-silicon molecular sieve is molded by special strong rotation molding equipment, so that the microsphere all-silicon molecular sieve catalyst with the MFI topological structure and higher strength and wear resistance is obtained. In a fluidized bed reaction system, the microsphere full-silicon molecular sieve catalyst disclosed by the invention is adopted to carry out cyclohexanone-oxime gas-phase Beckmann rearrangement reaction to prepare caprolactam, long-period and continuous production of caprolactam can be realized, the total selectivity and the total yield of caprolactam are higher than those of the existing full-silicon molecular sieve catalyst, the energy consumption for separating the product is reduced due to the reduction of the total amount of byproducts, and the technical economy is effectively improved.

Drawings

FIG. 1 is a photograph of a microspherical all-silica molecular sieve catalyst of MFI topology with very small amounts of rare earth ions prepared in example 1.

Detailed Description

The present invention will be further described with reference to the following examples. The BET specific surface area and the external specific surface area of the all-silicon molecular sieve samples in the examples are measured by an automatic adsorption instrument of American Micromeritics ASAP-2400 type, and the test conditions are as follows: n is a radical of₂As adsorbate, the adsorption temperature is-196.15 deg.C (liquid nitrogen temperature), and degassing is carried out at constant temperature of 1.3Pa and 300 deg.C for 6 h. The content of the rare earth ions of the sample is measured by using a Baird PS-4 type ICP-AES plasma inductively coupled atomic emission spectrometer, and the test conditions are as follows: dissolving with HF acid or aqua regiaAnd (3) decomposing the solid molecular sieve or the catalyst, and enabling the silicon oxide in the sample to be volatile and to be measured in an aqueous solution. The particle size distribution of the catalyst is measured by a BT-9300S type laser particle size distribution instrument of Baite instruments Limited, Dong, the test method is a wet test, water is used as a medium, and the sample concentration is as follows: 0.5-2% and the scanning speed is 2000 times/second. The morphology of the catalyst was photographed with a common camera. The catalyst attrition index K was measured on an attrition index analyzer according to the RIPP29-90 method in the petrochemical analysis method (Yankeeding et al, scientific Press, 1990).

General examples

A rotational molding preparation method of a microsphere all-silicon molecular sieve catalyst with an MFI topological structure and containing trace rare earth ions comprises the following steps:

c. Crushing the MFI topological structure all-silicon molecular sieve containing trace rare earth ions into 100-0000 meshes, mixing with a binder, and rotationally forming into a microsphere all-silicon molecular sieve catalyst with an MFI topological structure and a particle size of 20-400 mu m by using a rotary forming machine; the rotating speed of the rotating forming machine is 30-70rpm, and the inclination angle of the rotating disc is 0-30 degrees.

Preferably, the mixing in step a may be performed at a temperature of 10 to 50 ℃ and the mixing time may be 0.5 to 10 hours.

Preferably, the obtained catalyst comprises 80-90 wt% of MFI topological structure all-silicon molecular sieve and 10-20 wt% of binder on a dry basis weight basis.

Preferably, the binder may be a silica sol, an acidic silica sol, or a basic silica sol, and may be commercially available or prepared according to any one of the prior art, for example, the method disclosed in patent CN 1600428A. Preferably, the binder is alkaline silica sol, the pH value of the alkaline silica sol is preferably 8.5-13.5, more preferably 9-12, the content of sodium ions is preferably 10-500ppm, and SiO is₂The content is preferably 25 to 45 wt%; roasting to obtain SiO₂Preferably 100-250m²/g。

A process for producing caprolactam, comprising: the cyclohexanone oxime is contacted with the catalyst prepared by the method in the presence of a solvent to carry out gas-phase Beckmann rearrangement reaction.

When the microsphere all-silicon molecular sieve catalyst containing extremely trace rare earth ions and having an MFI topological structure disclosed by the invention is applied to a 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 the total caprolactam selectivity and total caprolactam 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.

Example 1

416kg of ethyl orthosilicate, 360kg of 22.5% by weight tetrapropylammonium hydroxide, 14.6gCe (NO)₃)₄·7H₂O and 440kg of water are mixed and stirred for 5 hours at normal temperature to form a colloidal mixture with the pH value of 12.45, and the molar ratio of the mixture is SiO₂∶TPAOH∶ H₂O＝1∶0.2∶20，SiO₂And Ce³⁺Is 30300: 1, transferring the mixture to 2m³In a stainless steel reaction kettle, firstly carrying out hydrothermal crystallization at 50 ℃ for 1 day, then carrying out hydrothermal crystallization at 100 ℃ for 2 days, wherein the pH value of a crystallization product is 13.55, then carrying out membrane filtration by adopting a 50nm six-tube membrane and washing by adopting water at 40-60 ℃, and the dosage of washing water is 7.0m³The pH of the washing water of the crystallized product reached 9.1. Concentrating the slurry obtained after washing: 395kg of molecular sieve slurry with the solid content of 26.8 percent by weight is sent to microwave drying and dried for 1 hour at the temperature of 100-150 ℃ to obtain about 125kg of all-silicon molecular sieve raw powder.

The above all-silicon-1 molecular sieve is calcined at 550 ℃ for 6 hours, the cerium ion content of the sample is 32ppm, the BET specific surface area is 442 m²Per gram, external specific surface 58 m²Per gram.

And (3) crushing the raw powder of the all-silicon molecular sieve on a crusher by using a 200-mesh screen, and repeating the operation for 2 times to obtain a powder sample of 200-1000 meshes. Pouring 15kg of molecular sieve powder sample with 200-1000 meshes into a sugar coating machine with the diameter of 1.2m, wherein the dip angle of the sugar coating machine is 10 degrees, the rotating speed of the sugar coating machine is 50rpm, and the rotation speed is 5min, 10.6kg of 30 wt.% alkaline silica sol (pH 9.5, sodium ion content 324ppm, SiO) was injected in portions₂The content is 40 weight percent, and SiO is obtained after roasting₂Has a surface area of 225m²And/g) uniformly spraying the powder, and stirring for 60min by rotation to obtain about 17kg of microsphere molecular sieve with the granularity of 30-200 mu m and a plurality of kg of other unqualified materials, wherein the unqualified materials are crushed on the crusher again to be used as raw materials for next use. The microsphere molecular sieve is respectively roasted at 280 ℃, 400 ℃ and 480 ℃ for 2h, and finally at 550 ℃ for 12 h to obtain about 10kg of microsphere molecular sieve, wherein the content of the full-silicon molecular sieve containing trace rare earth ions is 80 wt%, and the content of the adhesive silica sol is 20 wt%.

100g of the above microspherical molecular sieve and 1000g of a nitrogen-containing compound alkaline buffer solution (the nitrogen-containing compound 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 is 11.35) are added into a 2L stainless steel reaction kettle (KCF-2 type magnetic stirring autoclave, Nicotiana Hippocampus Kogyo Seisakusho) and the mixture is subjected to reaction at 82 ℃ and 2.3kg/cm²Stirring for 1.5 hours under pressure, then filtering, washing until the pH of the filtered clear solution is 9, and then drying for 24 hours at 120 ℃ to obtain the microsphere molecular sieve catalyst with the code A1.

The photograph of catalyst A1 is shown in FIG. 1, and it can be seen that the catalyst formed microspheres of uniform particle size; the abrasion index K is 4.2; the results of the particle size distribution tests are shown in Table 1, and it can be seen that the particle size of catalyst A1 is concentrated in the range of 40-200. mu.m.

TABLE 1

Example 2

416kg of ethyl orthosilicate, 360kg of 22.5% by weight tetrapropylammonium hydroxide, 28gCe (NO)₃)₃·6H₂O and 440kg of water are mixed and stirred for 5 hours at normal temperature to form a colloidal mixture with the pH value of 12.47, and the molar ratio of the mixture is SiO₂∶TPAOH∶ H₂O＝1∶0.2∶20，SiO₂And C_e ³⁺In a mass ratio of 13500: 1, the mixture was transferred to 2m³In a stainless steel reaction kettle, firstly carrying out hydrothermal crystallization at 50 ℃ for 1.5 days, then carrying out hydrothermal crystallization at 100 ℃ for 1.5 days, wherein the pH value of a crystallization product is 13.73, then carrying out membrane filtration by adopting a 50nm six-tube membrane and washing by adopting water at 40-60 ℃, and the dosage of washing water is 6.7m³The pH of the washing water of the crystallized product reached 9.1. Concentrating the slurry obtained after washing: 310kg of molecular sieve slurry with the solid content of 34.5 wt% is obtained, and is sent to microwave drying and dried for 1 hour at the temperature of 100-150 ℃ to obtain about 125kg of all-silicon molecular sieve raw powder.

The above all-silicon-1 molecular sieve is calcined at 550 ℃ for 6 hours, the cerium ion content of the sample is 73ppm, the BET specific surface area is 434 m²Per gram, external specific surface 56 m²Per gram.

And (3) crushing the raw powder of the all-silicon molecular sieve on a crusher by using a 200-mesh screen, and repeating the operation for 2 times to obtain a powder sample of 200-1000 meshes. Pouring 15kg of 200-1000 mesh molecular sieve powder sample into a sugar coating machine with the diameter of 1.2m, inclining the sugar coating machine at an angle of 15 degrees, rotating the sugar coating machine at a speed of 60rpm for 5min, and injecting 7.5kg of 30wt% alkaline silica sol (with the pH value of 9.5, the sodium ion content of 324ppm and the SiO content of 324 ppm) for multiple times₂The content is 40 weight percent, and SiO is obtained after roasting₂Has a surface area of 225m²And/g) uniformly spraying the powder, and stirring for 60min by rotation to obtain about 17kg of microsphere molecular sieve with the granularity of 50-200 mu m and a plurality of kg of other unqualified materials, wherein the unqualified materials are crushed on the crusher again to be used as raw materials for next use. Roasting the microspherical molecular sieve at 280 deg.C, 400 deg.C and 480 deg.C for 2 hr respectively, and finally at 550 deg.C for 12 hr to obtain about 10kg microspherical molecular sieve, in which the content of full-silicon molecular sieve containing trace rare earth ions is 85 wt%, and bindingThe content of the agent silica sol was 15% by weight.

Adding 95g of the microsphere molecular sieve and 950g of a basic buffer solution of a nitrogen-containing compound (the basic buffer solution of the nitrogen-containing compound is a mixed solution of ammonia water and an ammonium acetate water solution, wherein the ammonia water content is 26 wt%, the ammonium acetate content in the ammonium acetate water solution is 7.5 wt%, the weight ratio of the ammonia water to the ammonium acetate water solution is 3: 2, and the pH value is 11.39) into a 2L stainless steel reaction kettle, and adding the mixture into the reaction kettle at 90 ℃ and 2.8kg/cm²Stirring for 1.5 hours under pressure, filtering, drying for 24 hours at 120 ℃, repeating the contact operation of the basic buffer solution containing the nitrogen compound once again under the same conditions, filtering again, washing until the pH of the filtered clear liquid is 9, and drying for 24 hours at 120 ℃ to obtain the microsphere molecular sieve catalyst with the code of A2.

The photograph of catalyst a2 is similar to that of fig. 1; the abrasion index K is 4.0; the results of the particle size distribution test showed that the particle size of catalyst A2 was concentrated in the range of 40-200. mu.m.

Example 3

416kg of ethyl orthosilicate, 360kg of 22.5% by weight tetrapropylammonium hydroxide, 7.4 g of Ce (OAc)₃·5H₂O and 440kg of water, and stirring the mixture at normal temperature for 5 hours to form a colloidal mixture, wherein the colloidal mixture has a pH value of 12.46 and the molar ratio of the mixture is SiO₂∶TPAOH∶H₂O＝1∶0.2∶20，SiO₂And C_e ³⁺Is 48000: 1, the mixture is transferred to 2m³In a stainless steel reaction kettle, firstly carrying out hydrothermal crystallization at 60 ℃ for 1 day, then carrying out hydrothermal crystallization at 100 ℃ for 2 days, wherein the pH value of a crystallization product is 13.42, then carrying out membrane filtration by adopting a 50nm six-tube membrane, and washing by adopting water at 40-60 ℃, wherein the dosage of washing water is 6.7m³The pH of the washing water of the crystallized product reached 9.1. Concentrating the slurry obtained after washing: obtaining 310kg of molecular sieve slurry with the solid content of 28.4 weight percent, sending the molecular sieve slurry to microwave drying, and drying for 1 hour at the temperature of 100-150 ℃ to obtain about 127kg of all-silicon molecular sieve raw powder.

The above all-silicon-1 molecular sieve is calcined at 550 ℃ for 6 hours, the cerium ion content of the sample is 21ppm, the BET specific surface area is 442 m²Per gram, external specific surface 62 m²Per gram.

And (3) crushing the raw powder of the all-silicon molecular sieve on a crusher by using a 200-mesh screen, and repeating the operation for 2 times to obtain a powder sample of 200-1000 meshes. Pouring 15kg of 200-1000 mesh molecular sieve powder sample into a sugar coating machine with the diameter of 1.2m, pouring the sugar coating machine with the inclination angle of 20 degrees and the rotating speed of 50rpm, rotating for 5min, and then injecting 13.4kg of 30wt% alkaline silica sol (with the pH value of 9.5, the sodium ion content of 324ppm and the SiO content of 324 ppm) for multiple times₂The content is 40 weight percent, and SiO is obtained after roasting₂Has a surface area of 225m²And/g) uniformly spraying the powder, and stirring for 60min by rotation to obtain about 17kg of microsphere molecular sieve with the granularity of 50-200 mu m and a plurality of kg of other unqualified materials, wherein the unqualified materials are crushed on the crusher again to be used as raw materials for next use. The microsphere molecular sieve is respectively roasted at 280 ℃, 400 ℃ and 480 ℃ for 2h, and finally at 550 ℃ for 12 h to obtain about 10kg of microsphere molecular sieve, wherein the content of the all-silicon molecular sieve containing trace rare earth ions is 76 wt%, and the content of the adhesive silica sol is 24 wt%.

Adding 100g of the microsphere molecular sieve and 1000g of a nitrogen-containing compound alkaline buffer solution (the nitrogen-containing compound 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 is 11.35) into a 2L stainless steel reaction kettle, and adding the mixture into the stainless steel reaction kettle at 100 ℃ and 4.5kg/cm²Stirring for 1.5 hours under pressure, filtering, drying for 24 hours at 120 ℃, repeating the contact operation of the basic buffer solution containing the nitrogen compound once again under the same conditions, filtering again, washing until the pH of the filtered clear solution is 9, and drying for 24 hours at 120 ℃ to obtain the microsphere molecular sieve catalyst with the code of A3.

The photograph of catalyst a3 is similar to that of fig. 1; the abrasion index K is 2.6; the results of the particle size distribution test showed that the particle size of catalyst A3 was concentrated in the range of 40-200. mu.m.

Example 4

416kg of ethyl orthosilicate, 720kg of 22.5 wt% tetrapropylammonium hydroxide and 370kg of ethanol40.4 g Ce (NO)₃) ₄·7H₂Mixing O with 880kg of water, stirring at room temperature for 5 hours to form a colloidal mixture with a pH of 12.58, the molar ratio of the mixture being SiO₂∶TPAOH∶H₂O＝1∶0.4∶40，SiO₂And C_e ⁴⁺The mass ratio of (1) to (2) is 10900: 1, ethanol/SiO₂Transferring the mixture to 5m³In a stainless steel reaction kettle, firstly carrying out hydrothermal crystallization at 50 ℃ for 1 day, then carrying out hydrothermal crystallization at 100 ℃ for 2 days, wherein the pH value of a crystallization product is 13.80, then carrying out membrane filtration by adopting a 50nm six-tube membrane and washing by adopting water at 40-60 ℃, and the using amount of the washing water is 7.5m³The pH of the washing water of the crystallized product reached 9.1. Concentrating the slurry obtained after washing: 350kg of molecular sieve slurry with the solid content of 30.7 wt% is obtained, and is sent to microwave drying and dried for 1 hour at the temperature of 100-150 ℃ to obtain about 127kg of raw powder of the all-silicon molecular sieve.

The above all-silicon-1 molecular sieve is calcined at 550 ℃ for 6 hours, the cerium ion content of the sample is 90ppm, the BET specific surface area is 432 meters²Per gram, external specific surface 52 m²Per gram.

And (3) crushing the raw powder of the all-silicon molecular sieve on a crusher by using a 200-mesh screen, and repeating the operation for 2 times to obtain a powder sample of 200-1000 meshes. Pouring 15kg of 200-1000 mesh molecular sieve powder sample into a sugar coating machine with the diameter of 1.2m, inclining the sugar coating machine at an angle of 10 degrees, rotating the sugar coating machine at a speed of 40rpm for 5min, and injecting 10.5kg of 30wt% alkaline silica sol (with the pH value of 9.5, the sodium ion content of 324ppm and the SiO content of 324 ppm) for multiple times₂The content is 40 weight percent, and SiO is obtained after roasting₂Has a surface area of 225m²And/g) uniformly spraying the powder, and rotating and stirring for 60min to obtain about 10kg of microsphere molecular sieve with the granularity of 100-200 mu m and a plurality of kg of other unqualified materials, wherein the unqualified materials are crushed on the crusher again to be used as raw materials for next use. The microsphere molecular sieve is respectively roasted at 280 ℃, 400 ℃ and 480 ℃ for 2h, and finally at 550 ℃ for 12 h to obtain about 10kg of microsphere molecular sieve, wherein the content of the full-silicon molecular sieve containing trace rare earth ions is 80 wt%, and the content of the adhesive silica sol is 20 wt%.

100g of the microsphere molecular sieve and 1000g of a nitrogen-containing compound alkaline buffer solution (the nitrogen-containing compound 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 is 11.35) are added into a 2L stainless steel reaction kettle, and the mixture is subjected to reaction at 82 ℃ and 2.3kg/cm²Stirring for 1.5 hours under pressure, filtering, drying for 24 hours at 120 ℃, repeating the contact operation of the basic buffer solution containing the nitrogen compound once again under the same conditions, filtering again, washing until the pH of the filtered clear liquid is 9, and drying for 24 hours at 120 ℃ to obtain the microsphere molecular sieve catalyst with the code of A4.

The photograph of catalyst a4 is similar to that of fig. 1; the abrasion index K is 4.1; the results of the particle size distribution test showed that the particle size of catalyst A4 was concentrated in the range of 40-200. mu.m.

Example 5

208kg of ethyl orthosilicate, 90kg of 22.5 wt% tetrapropylammonium hydroxide, 276kg of ethanol and 24 g of La (NO)₃)₃·6H₂Mixing O with 110kg of water, stirring at normal temperature for 5 hours to form a colloidal mixture with a pH value of 12.91, wherein the molar ratio of the mixture is SiO₂∶TPAOH∶H₂O＝1∶0.1∶10，SiO₂And La³⁺The mass ratio of (1) to (2) is 15300: 1, ethanol/SiO₂Transferring the mixture to 1m ═ 10³In a stainless steel reaction kettle, firstly carrying out hydrothermal crystallization for 2 days at 50 ℃, then carrying out hydrothermal crystallization for 2 days at 100 ℃, wherein the pH value of a crystallization product is 13.48, then carrying out membrane filtration by adopting a 50nm six-tube membrane and washing by adopting water at 40-60 ℃, and the dosage of washing water is 6.5m³The pH of the washing water of the crystallized product reached 9.1. Concentrating the slurry obtained after washing: 160kg of molecular sieve slurry with the solid content of 34.1 weight percent is obtained, and is sent to microwave drying and dried for 1 hour at the temperature of 100-150 ℃ to obtain about 125kg of raw powder of the all-silicon molecular sieve.

The above all-silicon-1 molecular sieve was calcined at 550 ℃ for 6 hours, and the lanthanum ion content of the sample was 63ppm, and the BET specific surface area was 451 m²Per gram, external specific surface 67 m²Per gram.

And (3) crushing the raw powder of the all-silicon molecular sieve on a crusher by using a 200-mesh screen, and repeating the operation for 2 times to obtain a powder sample of 200-1000 meshes. Pouring 15kg of 200-1000 mesh molecular sieve powder sample into a sugar coating machine with the diameter of 1.2m, inclining the sugar coating machine at an angle of 10 degrees, rotating the sugar coating machine at a speed of 50rpm for 5min, and injecting 4.8kg of 30wt% alkaline silica sol (with the pH value of 9.5, the sodium ion content of 324ppm and the SiO content of 324 ppm) for multiple times₂The content is 40 weight percent, and SiO is obtained after roasting₂Has a surface area of 225m²And/g) uniformly spraying the powder, and stirring for 60min by rotation to obtain about 8kg of microsphere molecular sieve with the granularity of 100-200 mu m and a plurality of kg of other unqualified materials, wherein the unqualified materials are crushed on the crusher again to be used as raw materials for next use. The microsphere molecular sieve is respectively roasted at 280 ℃, 400 ℃ and 480 ℃ for 2h, and finally at 550 ℃ for 12 h to obtain about 10.4kg of microsphere molecular sieve, wherein the content of the full-silicon molecular sieve containing trace rare earth ions is 90wt%, and the content of the adhesive silica sol is 10 wt%.

100g of the microsphere molecular sieve and 1000g of a nitrogen-containing compound alkaline buffer solution (the nitrogen-containing compound 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 is 11.4) are added into a 2L stainless steel reaction kettle, and the mixture is subjected to reaction at 80 ℃ and 2.0kg/cm²Stirring for 1.5 hours under pressure, then filtering, washing until the pH of the filtered clear solution is 9, and then drying for 24 hours at 120 ℃ to obtain the microsphere molecular sieve catalyst with the code A5.

The photograph of catalyst a5 is similar to that of fig. 1; the abrasion index K is 5.0; the results of the particle size distribution test showed that the particle size of catalyst A5 was concentrated in the range of 40-200. mu.m.

Example 6

416kg of ethyl orthosilicate, 360kg of 22.5% by weight tetrapropylammonium hydroxide, 550kg of ethanol, 2.6 g of La (OAc)₃·5H₂O and 260kg of water are mixed and stirred for 6 hours at normal temperature to form a colloidal mixture with the pH value of 12.85, and the molar ratio of the mixture is SiO₂∶TPAOH∶H₂O＝1∶0.2∶15，SiO₂And La³⁺With a mass ratio of 140000: 1, ethanol/SiO₂Transfer the mixture to 3m³In a stainless steel reaction kettle, firstly carrying out hydrothermal crystallization at 60 ℃ for 1 day, then carrying out hydrothermal crystallization at 100 ℃ for 2 days, wherein the pH value of a crystallization product is 13.55, then carrying out membrane filtration by adopting a 50nm six-tube membrane, and washing by adopting water at 40-60 ℃, wherein the dosage of washing water is 6.8m³The pH of the washing water of the crystallized product reached 9.1. Concentrating the slurry obtained after washing: 395kg of molecular sieve slurry with the solid content of 26.8 weight percent is obtained and sent to microwave drying, and the molecular sieve slurry is dried for 1 hour at the temperature of 100-150 ℃ to obtain about 120kg of all-silicon molecular sieve raw powder.

The above all-silicon-1 molecular sieve is calcined at 550 ℃ for 6 hours, the lanthanum ion content of the sample is 7ppm, the BET specific surface area is 447 m²Per gram, external specific surface 64 m²Per gram.

And (3) crushing the raw powder of the all-silicon molecular sieve on a crusher by using a 200-mesh screen, and repeating the operation for 2 times to obtain a powder sample of 200-1000 meshes. Pouring 15kg of 200-1000 mesh molecular sieve powder sample into a sugar coating machine with the diameter of 1.2m, inclining the sugar coating machine at an angle of 10 degrees and rotating the sugar coating machine at a speed of 60rpm for 5min, and then injecting 10.6kg of 30wt% alkaline silica sol (with the pH value of 9.5, the sodium ion content of 324ppm and the SiO content of 324 ppm) for multiple times₂The content is 40 weight percent, and SiO is obtained after roasting₂Has a surface area of 225m²And/g) and uniformly spraying the powder, and rotating and stirring for 60min to obtain about 17kg of microsphere molecular sieve with the granularity of 100-200 mu m and a plurality of kg of other unqualified materials. And (2) roasting the microsphere molecular sieve at 280 ℃, 400 ℃ and 480 ℃ for 2h respectively, and finally at 550 ℃ for 12 h to obtain about 10kg of microsphere molecular sieve, wherein the content of the all-silica molecular sieve containing trace rare earth ions is 80 wt%, and the content of the binder silica sol is 20 wt%.

100g of the microsphere molecular sieve and 1000g of a nitrogen-containing compound alkaline buffer solution (the nitrogen-containing compound 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%, and the weight ratio of the ammonia water to the ammonium nitrate aqueous solution is3: 2, pH 11.35) was added to a 2L stainless steel reactor at 82 ℃ under 2.3kg/cm²Stirring for 1.5 hours under pressure, filtering, drying for 24 hours at 120 ℃, repeating the contact operation of the basic buffer solution containing the nitrogen compound once again under the same conditions, filtering again, washing until the pH of the filtered clear liquid is 9, and drying for 24 hours at 120 ℃ to obtain the microsphere molecular sieve catalyst with the code of A6.

The photograph of catalyst a6 is similar to that of fig. 1; the abrasion index K is 4.6; the results of the particle size distribution test showed that the particle size of catalyst A6 was concentrated in the range of 40-200. mu.m.

From the results of examples 1-6, it can be seen that the microspherical all-silica molecular sieve catalyst containing extremely small amount of rare earth ions has low attrition index, and thus can be used in the fluidized bed process for preparing caprolactam by gas phase Beckmann rearrangement of cyclohexanone oxime.

Test examples

This test example is provided to illustrate the catalytic reaction results of the all-silica molecular sieve catalysts prepared in examples 1 to 6 in the gas phase beckmann rearrangement reaction.

The cyclohexanone oxime gas phase Beckmann rearrangement reaction is carried out by using catalysts A1-A6 respectively under the following conditions:

performing cyclohexanone-oxime gas-phase Beckmann rearrangement reaction in a stainless steel fixed bed reactor, wherein the inner diameter of the reactor is 5mm, 0.469 g of catalyst with 40-60 meshes is filled in the reactor, coarse quartz sand with the height of about 30mm and the size of 30 meshes is filled on the upper surface of a catalyst bed layer, and fine quartz sand with the size of 50 meshes is filled below the catalyst bed layer. The rearrangement reaction conditions are as follows: normal pressure; the reaction temperature is 380 ℃; the weight space velocity (WHSV, cyclohexanone oxime flow in feeding/catalyst weight in bed) of the cyclohexanone oxime is 16h^-1(ii) a The reaction solvent is methanol, and the weight of the methanol is 65 percent of that of the reaction raw materials; carrier gas (N)₂) The flow rate 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 composition analysis of the product is carried out after the reaction is carried out for 6 hours.

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, the temperature was maintained at 110 deg.C for 8 min, 15 deg.C/min was increased to 230 deg.C, and the temperature was maintained for 14 min.

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 content of cyclohexanone oxime in the reaction product and the molar percentage content of caprolactam in the reaction product are obtained through the analysis, and the conversion rate of cyclohexanone oxime and the 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% caprolactam mol/(100-cyclohexanone oxime mol%) in the reaction product

In the byproduct of the cyclohexanone oxime gas phase Beckmann rearrangement reaction, methyl-epsilon-caprolactam accounts for about 40 percent of the total amount of all the byproducts, and the byproducts are generated by the alcoholysis reaction of methanol and enol structure tautomer of caprolactam. Under the action of water, methyl-epsilon-caprolactam is continuously generated by hydrolysis reaction of methyl-epsilon-caprolactam. Thus, the amount of methyl-epsilon-caprolactam hydrolysis to caprolactam is included in the calculation of the total caprolactam selectivity.

TABLE 2

Catalyst numbering	Cyclohexanone oxime conversion (mol%)	Caprolactam Total Selectivity (mol%)
			A1	99.45	95.25
A2	99.22	95.61
			A3	98.72	96.75
A4	99.01	96.26
			A5	99.38	95.80
A6	98.63	96.31

As can be seen from Table 2, the microsphere all-silica molecular sieve based catalyst containing trace rare earth ions prepared by the method disclosed by the invention has high cyclohexanone oxime conversion rate, and when the weight space velocity (WHSV) of cyclohexanone oxime is 16h^-1Then, the reaction time can reach 99.45 percent at most after 6 hours, and the selectivity to caprolactam is high and can reach 96.75 percent at most.

The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, alterations and equivalents of the above embodiments according to the technical spirit of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. The application of microsphere full-silicon molecular sieve catalyst containing trace rare earth ions and having MFI topological structure as gas phase Beckmann rearrangement catalyst in caprolactam production is characterized in that the microsphere full-silicon molecular sieve catalyst is prepared by adopting a rotation forming method, and comprises the following steps:

a. mixing a silicon source, a rare earth ion source, an organic template agent and water to obtain a colloid mixture; wherein SiO in the colloid mixture₂The mol ratio of the organic template agent to the water is 1 (0.05-0.50) to (5-100); the mass ratio of the silicon source to the rare earth ions is (10000- & lt 200000- & gt) 1; the rare earth ion is selected from Ce³⁺、Ce⁴⁺At least one of；

b. Carrying out hydrothermal crystallization on the colloid mixture at 50-60 ℃ for 0.5-3 days, then carrying out hydrothermal crystallization at 80-120 ℃ for 0.5-3 days, carrying out membrane filtration on the obtained crystallized product, washing until the pH value is 8-10, and drying to obtain the MFI topological structure all-silicon molecular sieve containing trace rare earth ions;

c. crushing the full-silicon molecular sieve containing trace rare earth ions and having an MFI topological structure into 100-0000 meshes, mixing the crushed full-silicon molecular sieve with a binder, and rotationally forming the mixture into a microsphere full-silicon molecular sieve catalyst with an MFI topological structure and a particle size of 20-400 mu m by using a rotary forming machine; the rotating speed of a rotating disc of the rotating forming machine is 30-70rpm, and the inclination angle of the rotating disc is 0-30 degrees;

2. The use of claim 1, wherein the obtained catalyst comprises 70-95 wt% of the all-silica molecular sieve with MFI topology containing trace rare earth ions and 5-30wt% of the binder, based on the dry weight; the particle size of the catalyst is 40-200 mu m, and the abrasion index K is less than 5.

3. The use of claim 2, wherein the BET specific surface area of the all-silica molecular sieve with MFI topology containing trace amounts of rare earth ions is 400-500m²(g), the weight ratio of silicon dioxide to rare earth ions in the all-silicon molecular sieve with MFI topological structure is (10000- & 200000): 1.

4. the use of claim 2, wherein the resulting catalyst comprises 80 to 90wt% of the all-silica molecular sieve having MFI topology, and 10 to 20wt% of the binder, on a dry weight basis.

5. Use according to claim 1, characterized in thatThe adhesive is silica sol, the sodium ion content of the silica sol is 10-500ppm, and SiO is₂The content is 20-45 wt%.

6. The use of claim 1, wherein in step a, the rare earth ion source is at least one of a nitrate, a chlorate, an acetate and a carbonate containing the rare earth ion.

7. The use of claim 1, wherein in step a, the silicon source is selected from at least one of silica gel, silica sol and organosilicate; the organic template agent is selected from at least one of fatty amine compounds, alcohol amine compounds and quaternary ammonium base compounds; wherein the general formula of the aliphatic amine compound is R²（NH₂）_n，R²Is alkyl with 1-6 carbon atoms, n is an integer between 1-3, and the alcohol amine compound has a general formula of (HOR)³)_mN，R³Is alkyl with 1-4 carbon atoms, m is an integer between 1-3, and the alkyl quaternary ammonium base compound has 1-4 carbon atoms.

8. The use according to claim 7, wherein the organosilicate has the formula (OR)¹）₄Si, wherein R¹Is an alkyl group of 1 to 4 carbon atoms.

9. Use according to claim 8, wherein the organosilicate is methyl orthosilicate and/or ethyl orthosilicate; the organic template agent is an alkyl quaternary ammonium base compound and/or a fatty amine compound; the alkyl quaternary ammonium alkali compound is tetraethyl ammonium hydroxide and/or tetrapropyl ammonium hydroxide; the aliphatic amine compound is at least one of ethylamine, n-butylamine, n-propylamine, ethylenediamine and hexamethylenediamine.

10. The use of claim 1, wherein in step a, said colloidal mixture further comprises a lower alcohol, said lower alcoholCarbon alcohol and SiO₂In a molar ratio of 1: (4-15).

11. The use according to claim 1, wherein in step c, the rotational molding is carried out with the addition of an additive selected from at least one of sesbania powder, graphite, activated carbon, paraffin, stearic acid, glycerin, oxalic acid, tartaric acid, citric acid, starch, polyethylene glycol, polyvinyl alcohol, polyethylene oxide, polyallylamine, cellulose methyl ether, cellulose, polymeric alcohol, nitric acid, hydrochloric acid, acetic acid, formic acid, aqueous ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide; the dosage of the additive is 1-5 wt% of the dry weight of the molecular sieve.

12. The use according to claim 1, wherein in step d, the nitrogen-containing compound alkaline buffer solution contains ammonium salt and alkali, the ammonium salt content is 0.5-20wt%, the alkali content is 5-30wt%, and the nitrogen-containing compound alkaline buffer solution has a pH value of 8.5-13.5.

13. The use of claim 12, wherein the ammonium salt is at least one of ammonium carbonate, ammonium fluoride, ammonium chloride, ammonium acetate, and ammonium nitrate; the alkali is at least one of ammonia water, tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide and tetrapropyl ammonium hydroxide.

14. Use according to claim 13, wherein the ammonium salt is ammonium acetate and/or ammonium nitrate; the alkali is ammonia water.

15. The use of claim 1, wherein in step d, the weight ratio of the calcined molecular sieve to the basic buffer solution of nitrogen-containing compound on a dry basis is from 1: (5-15), the contact temperature is 50-120 ℃, and the contact pressure is 0.5-5kg/cm²The contact time is 10 to 300 minutes, and whether to repeat several times depending on the performance of the catalyst is determinedAnd (6) processing.

16. The use of claim 1, wherein in step d, the firing conditions are: the temperature is 200 ℃ and 600 ℃ and the time is 1-20 hours.

17. A process for producing caprolactam, comprising: contacting cyclohexanone oxime in the presence of a solvent with a catalyst prepared by the process of any one of claims 1-16 to effect a vapor phase beckmann rearrangement.

18. The process according to claim 17, wherein the molar ratio of the solvent to cyclohexanone oxime is (2-10): 1; the solvent is selected from fatty alcohol of C1-C6.

19. The process according to claim 17, wherein the gas phase beckmann rearrangement reaction is carried out in the presence of nitrogen gas at a molar ratio of nitrogen gas to cyclohexanone oxime of (10-80): 1.

20. the process of claim 17, wherein the gas phase beckmann rearrangement reaction is carried out under conditions of: the weight space velocity of the cyclohexanone-oxime is 0.1-20 hours^-1The reaction temperature is 300-500 ℃, and the reaction pressure is 0.1-0.5 MPa.

21. The method of claim 17, further comprising reacting the cyclohexanone oxime with water in a molar ratio of 1: (0.01-2.5) and then contacting the mixture with the catalyst in the presence of the solvent to perform a gas phase Beckmann rearrangement reaction.