CN109718825B

CN109718825B - Microsphere Silicate-1 molecular sieve catalyst, preparation method thereof and method for preparing caprolactam

Info

Publication number: CN109718825B
Application number: CN201711024212.3A
Authority: CN
Inventors: 程时标; 谢丽; 张树忠; 慕旭宏; 宗保宁
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2017-10-27
Filing date: 2017-10-27
Publication date: 2022-06-28
Anticipated expiration: 2037-10-27
Also published as: CN109718825A

Abstract

The invention relates to a microsphere Silicate-1 molecular sieve catalyst containing trace metal ions, a preparation method thereof and a method for preparing caprolactam from cyclohexanone oxime, wherein the catalyst comprises a Silicate-1 molecular sieve containing trace metal ions and a binder, wherein the Silicate-1 molecular sieve contains 70-95 wt% of trace metal ions and 5-30 wt% of binder, and the weight of the binder is based on the dry weight of the catalyst; the particle size of the catalyst is 20-300 mu m, and the abrasion index K is less than 8; the BET specific surface area of the Silicate-1 molecular sieve is 400-500 m²(iii) the weight ratio of silicon oxide to metal ion is (5000-: 1. the catalyst has low abrasion index, and can effectively improve the selectivity of caprolactam when being used for carrying out gas-phase Beckmann rearrangement reaction of cyclohexanone oxime in a fluidized bed process.

Description

Microsphere Silicate-1 molecular sieve catalyst, preparation method thereof and method for preparing caprolactam

Technical Field

The disclosure relates to a microsphere Silicate-1 molecular sieve catalyst containing trace metal ions, a preparation method thereof and a method for preparing caprolactam from cyclohexanone oxime.

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 aluminum-free all-silicon-1 molecular sieve with MFI topological structure, is a simplest molecular sieve 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 SiO ₄A tetrahedron. The all-silicon-1 molecular sieve has rich microporous structure and regular and uniform three-dimensional fine pore channels, has a determined crystal structure of the ZSM-5 type molecular sieve, and has the performances of higher internal specific surface area, good thermal stability, 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 sound 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.

Because the all-silicon-1 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 is difficult to realize.

Caprolactam is a main raw material for producing three series products of chinlon, industrial cord and nylon engineering plastics, and the demand of the caprolactam 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 such as equipment corrosion and environmental pollution.

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 a 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, have short service life and can not meet the requirements of industrialization.

The process which makes the production more economical and meets the greening requirement 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 catalysts as used in british patent GB881,927; solid phosphoric acid catalysts as used in british patent GB881,956; catalysts 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 petrochemical field. Spray forming belongs to a combined technological process of spraying and drying. The raw material slurry is sprayed into extremely fine atomized liquid drops under the action of an atomizer, then the atomized 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.

The spray forming is divided into three types, namely a pressure type, a centrifugal disc type and an air flow type, and has the characteristics of simple process flow, convenient production, strong production capacity, 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 of molecular sieves by spray drying without any binder and then to heat treat them in water to increase their mechanical strength 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 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 fluidized bed reactors.

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.

Because the investment cost of the fluidized bed process is high, and only about 95 percent of cyclohexanone oxime is converted (the separation technology requires 100 percent of conversion), the development of a new fixed bed or moving bed process for the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime is necessary for industrial application. Meanwhile, the development of a method for preparing a spherical catalyst applied to a fixed bed or moving bed process is also mentioned on schedule. Until now, no relevant documents and patents about the application of the Silicalite-1 molecular sieve containing a trace amount of metal ions to the cyclohexanone oxime gas phase Beckmann rearrangement reaction by rotary (rotational) molding into a microspherical shape have been found.

Disclosure of Invention

The purpose of the disclosure is to provide a Silicate-1 microsphere molecular sieve catalyst containing trace metal ions, a preparation method thereof and a method for preparing caprolactam from cyclohexanone oxime, wherein the catalyst has low abrasion index, and can effectively improve the selectivity of caprolactam when being used for carrying out gas phase Beckmann rearrangement reaction of cyclohexanone oxime in a fluidized bed process.

To achieve the above object, a first aspect of the present disclosure: providing a microsphere Silicate-1 molecular sieve catalyst containing trace metal ions, wherein the catalyst comprises a Silicate-1 molecular sieve containing trace metal ions and a binder, wherein the Silicate-1 molecular sieve contains 70-95 wt% of trace metal ions and 5-30 wt% of binder, and the binder is based on the dry weight of the catalyst; the particle size of the catalyst is 20-300 mu m, and the abrasion index K is less than 8;

the BET specific surface area of the Silicate-1 molecular sieve is 400-500 m²(iii) the weight ratio of silicon oxide to metal ion is (5000-: 1.

optionally, the catalyst comprises 80 to 90 wt% of a Silicate-1 molecular sieve, and 10 to 20 wt% of a binder, based on the dry weight of the catalyst;

the particle size of the catalyst is 100-300 mu m, and the abrasion index K is less than 5.

Optionally, the metal ion is selected from Co²⁺、Ni²⁺、Cu²⁺、Zn²⁺、Fe²⁺、Mn²⁺、Cr³⁺、Fe³⁺、Ga³⁺、Al³⁺、Ti⁴⁺、Zr⁴⁺、Sn⁴⁺、Ge⁴⁺、Pb⁴⁺、Mn⁴⁺、V⁵⁺、Sb⁵⁺、Mn⁶⁺、Mo⁶⁺And W⁶⁺At least one of;

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

In a second aspect of the present disclosure: there is provided a process for preparing a microspherical Silicate-1 molecular sieve catalyst containing trace amounts of metal ions according to the first aspect of the disclosure, the process comprising:

a. mixing a silicon source, a metal ion source, an organic template and water to obtain a colloid mixture, wherein SiO in the colloid mixture is calculated by molar ratio₂: organic template agent: h₂O is 1: (0.05-0.50): (5-100), the weight ratio of the silicon oxide to the metal ions is (5000-: 1;

b. b, carrying out hydrothermal crystallization on the colloid mixture obtained in the step a at the temperature of 80-120 ℃ under autogenous pressure for 0.5-10 days, washing the obtained crystallization product until the pH value is 7.5-10, and drying to obtain a Silicate-1 molecular sieve containing trace metal ions;

c. b, crushing the Silicate-1 molecular sieve containing trace metal ions obtained in the step b into 60-500 meshes, mixing the crushed molecular sieve with a binder, and performing rotary molding to obtain a microsphere molecular sieve with the particle size of 20-300 mu m;

the rotary forming is carried out in a forming machine with an eccentric stirring paddle, a barrel body of the forming machine can rotate in a reverse direction with the stirring paddle, the forming machine is provided with a barrel cover matched with the barrel body, a scraper facing the barrel wall is arranged on the barrel cover and facing the interior of the barrel body and used for scraping materials splashed on the barrel wall in the rotary forming process, and the barrel body of the forming machine forms an inclination angle of 20-40 degrees with the vertical direction;

d. And c, roasting the microsphere molecular sieve obtained in the step c, contacting the roasted microsphere molecular sieve with an alkaline buffer solution containing a nitrogen compound, washing, filtering and drying to obtain the microsphere molecular sieve catalyst.

Optionally, in step a, the silicon source is at least one selected from silica gel, silica sol and organosilicate; preferably of the formula (OR)¹)₄Organosilicates of Si wherein R¹Is an alkyl group of 1 to 4 carbon atoms; more preferably methyl orthosilicate and/or ethyl orthosilicate;

the metal ion source is at least one of nitrate, chlorate, acetate, carbonate and ester compounds containing the metal ions;

the organic template agent is at least one selected from fatty amine compounds, alcohol amine compounds and quaternary ammonium base compounds; preferably alkyl quaternary ammonium base compounds having 1 to 4 carbon atoms; more preferably tetraethylammonium hydroxide and/or tetrapropylammonium hydroxide.

Optionally, the colloidal mixture in step a further comprises a lower alcohol, the lower alcohol being in contact with SiO₂In a molar ratio of 1: (4-15), wherein the lower alcohol is methanol and/or ethanol.

Optionally, in the step c, the rotating speed of the barrel body of the forming machine is 20-50rpm, and the rotating speed of the stirring paddle is 200 and 2000 rpm.

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

Optionally, in step d, the alkaline buffer solution containing the nitrogen-containing compound contains ammonium salt and alkali, the content of the ammonium salt is 0.5-20 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.

Optionally, in the step d, the weight ratio of the baked microspherical molecular sieve to the alkaline buffer solution containing the nitrogen compound on a dry basis is 1: (5-15), the contact temperature is 50-120 ℃, and the contact pressure is 0.5-5kg/cm²The contact time is 10-300 minutes.

A third aspect of the disclosure: provided is a process for producing caprolactam from cyclohexanone oxime, which comprises: the cyclohexanone oxime is contacted with the microsphere Silicate-1 molecular sieve catalyst containing trace metal ions in the first aspect of the disclosure in the presence of a solvent to carry out a gas phase Beckmann rearrangement reaction.

Alternatively, the molar ratio of the solvent to the cyclohexanone oxime is (2-10): 1;

the solvent is selected from C1-C6 fatty alcohol, preferably methanol and/or ethanol.

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

Optionally, the conditions under which the 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.

Optionally, the method further comprises, in a molar ratio of cyclohexanone oxime to water of 1: (0.01-2.5) and then contacting the microspheres with the microsphere Silicate-1 molecular sieve catalyst containing trace metal ions in the presence of the solvent to carry out gas-phase Beckmann rearrangement reaction.

According to the technical scheme, an extremely trace amount of metal ions are added in the synthesis process of the Silicate-1 molecular sieve, the performance of the Silicate-1 molecular sieve can be effectively changed, then the Silicate-1 molecular sieve is molded through special powerful rotating molding equipment, and the microsphere Silicate-1 molecular sieve catalyst with high strength and wear resistance is obtained. In a fluidized bed reaction system, the microsphere Silicate-1 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 Silicate-1 molecular sieve catalyst, the product separation energy consumption is reduced due to the reduction of the total amount of byproducts, and the technical economy is effectively improved.

Additional features and advantages of the present disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure, but do not constitute a limitation of the disclosure. In the drawings:

FIG. 1 is a photograph of microspheroidal molecular sieve Silicate-1 catalyst containing trace amounts of metal ions prepared in example 1.

Detailed Description

The following detailed description of the embodiments of the disclosure refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

The first aspect of the disclosure: a microspherical Silicate-1 molecular sieve catalyst containing trace metal ions is provided, the catalyst comprises Silicate-1 molecular sieve containing trace metal ions, 70-95 wt% of the catalyst based on the dry weight of the catalyst, and 5-30 wt% of a binder, preferably, the catalyst comprises Silicate-1 molecular sieve, 80-90 wt% of the catalyst based on the dry weight of the catalyst, and the binder is 10-20 wt%.

The microsphere Silicate-1 molecular sieve catalyst provided by the present disclosure has a suitable particle size and a relatively high attrition strength. The particle size of the catalyst is 20-300 μm, preferably 100-300 μm. The attrition index K of the catalyst is less than 8, further, the attrition index K is less than 5, the lower the attrition index K, the higher the attrition resistance of the catalyst is demonstrated.

According to the present disclosure, the BET specific surface area of the Silicate-1 molecular sieve may be 400-500 m²The grain size can be 0.1-0.2 μm, the weight ratio of silicon oxide and metal ion can be (5000-: 1.

in accordance with the present disclosure, the metal ion may be an ion of a metal element selected from group IB, group IIB, group IVB, group VB, group VIB, group VIIB, group IIIA, group IVA and group VA. Preferably, the metal ion is selected from Co²⁺、Ni²⁺、Cu²⁺、Zn²⁺、Fe²⁺、Mn²⁺、Cr³⁺、Fe³⁺、Ga³⁺、Al³⁺、Ti⁴⁺、Zr⁴⁺、Sn⁴⁺、Ge⁴⁺、Pb⁴⁺、Mn⁴⁺、V⁵⁺、Sb⁵ ⁺、Mn⁶⁺、Mo⁶⁺And W⁶⁺At least one of (a).

According to the present disclosure, the binder may be a silica sol, an acidic silica sol, or an alkaline silica sol, and may be obtained commercially 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 sodium ion content is preferably 10-500 ppm, and SiO is selected ₂The content is preferably 25 to 45 wt%; roasting to obtain SiO₂Preferably 100-250m²/g。

In a second aspect of the present disclosure: there is provided a process for preparing a microspheroidal Silicate-1 molecular sieve catalyst containing trace metal ions according to the first aspect of the present disclosure, which process comprises:

According to the present disclosure, the silicon source in step a may be a conventional choice in the art, and for example, may be at least one selected from silica gel, silica sol, and organosilicate; preferably of the formula (OR)¹)₄Organosilicates of Si wherein R¹Is an alkyl group of 1 to 4 carbon atoms; more preferably, it is methyl orthosilicate and/or ethyl orthosilicate.

In accordance with the present disclosure, the metal ion is one that readily or readily enters the framework of the molecular sieve, and may be, for example, an ion of a metal element selected from the group consisting of group IB, group IIB, group IVB, group VB, group VIB, group VIIB, group IIIA, group IVA, and group VA. Preferably, the metal ion is selected from Co²⁺、Ni²⁺、Cu²⁺、Zn²⁺、Fe²⁺、Mn²⁺、Cr³⁺、Fe³⁺、Ga³ ⁺、Al³⁺、Ti⁴⁺、Zr⁴⁺、Sn⁴⁺、Ge⁴⁺、Pb⁴⁺、Mn⁴⁺、V⁵⁺、Sb⁵⁺、Mn⁶⁺、Mo⁶⁺And W⁶⁺At least one of (1). More preferably, the metal ion is trivalent or tetravalent and is capable of entering the framework of the molecular sieve, and may be selected from Cr³⁺、Fe³⁺、Ga³⁺、Al³⁺、Ti⁴⁺、Zr⁴⁺、Sn⁴⁺、Ge⁴⁺、Pb⁴⁺And Mn⁴⁺At least one of (1). Further preferably, the metal ion is selected from Fe³⁺、Al³⁺、Ti⁴⁺And Zr ⁴⁺At least one of (a).

According to the present disclosure, the metal ion source in step a may be a compound containing the above metal ions, for example, nitrate, chlorate, acetate, carbonate and ester compounds (such as ethyl titanate, titanium) containing the above metal ionsButyl acetate, etc.). The present disclosure does not require any particular water-soluble compound containing the above metal ion, and any commercially available water-soluble compound material containing the above metal ion may be used, for example, when Al is introduced into the Silicate-1 molecular sieve³⁺In this case, SB powder, V250 powder, pseudo-boehmite, C-1 powder and the like can be used.

According to the present disclosure, the organic templating agent in step a may be a conventional choice in the art, and for example, may be at least one selected from the group consisting of fatty amine compounds, alcohol amine compounds, and quaternary amine 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 of 1 to 3, and the aliphatic amine compound is preferably at least one selected from the group consisting of ethylamine, n-butylamine, n-propylamine, ethylenediamine, and hexamethylenediamine. Wherein the general formula of the alcohol amine compound is (HOR) ³)_mN，R³Is an alkyl group having 1 to 4 carbon atoms, m is an integer of 1 to 3, and the alcohol amine compound is preferably at least one selected from the group consisting of monoethanolamine, diethanolamine and triethanolamine. The quaternary ammonium base compound is preferably an alkyl quaternary ammonium base compound having 1 to 4 carbon atoms, and more preferably tetraethylammonium hydroxide and/or tetrapropylammonium hydroxide.

In step a, according to the present disclosure, SiO in the colloidal mixture is preferably present in a molar ratio₂: organic template agent: h₂O is 1: (0.15-0.25): (10-50); the mass ratio of silicon oxide to metal ions is (10000) -100000): 1.

according to the present disclosure, in order to make the molecular sieve more favorable for the catalytic reaction, the colloid mixture in step a may further include a lower alcohol, and the lower alcohol is mixed with SiO₂May be 1: (4-15). Wherein the lower alcohol is methanol and/or ethanol.

According to the present disclosure, 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.

According to the disclosure, in the step b, after the colloid mixture is subjected to hydrothermal crystallization, the pH value of the crystallized product is about 13-14, and then the crystallized product may be subjected to membrane filtration and then washed until the pH value reaches a required range. The meaning of the membrane filtration and washing is well known to those skilled in the art, and the present disclosure is not particularly limited. For example, the crystallized product may be subjected to membrane filtration and washing using hot water, and the temperature of the hot water may be 20 to 70 ℃, preferably 40 to 50 ℃. The crystallized product is preferably washed to a pH value of 8-9.5. After washing, the obtained silica-1 molecular sieve-containing slurry can be concentrated until the content of the molecular sieve is 10-40 wt%, and then dried.

In step c, in order to further obtain a microspherical catalyst with a suitable particle size, the Silicate-1 molecular sieve containing trace metal ions is preferably crushed to 100-250 mesh and then mixed with a binder. The purpose of adding the binder is to make the molecular sieve powder particles mutually bonded together when rotating so as to improve the strength of the catalyst molded product. If the amount of the binder is not sufficient, the binder is difficult to form into balls, and if the binder is barely formed into balls, the binder may be broken when the binder leaves the molding machine. When the amount of the binder is too large, the spherical product becomes soft and sticky. The binder may be a silica sol having a solids content, for example an alkaline silica sol having a solids content of 20-50 wt%. The crushed molecular sieve powder can be mixed with the binder and then put into a forming machine for rotary forming, or the crushed molecular sieve powder can be put into the forming machine and then the binder is added under the stirring state. The binder is used in such an amount that the contents of the respective components of the finally obtained catalyst satisfy the conditions described in the first aspect of the present disclosure.

It is essential in the method of the present disclosure that the rotational forming, alternatively also referred to as rotational forming, is carried out in a special forming machine. Mixing the crushed Silicate-1 molecular sieve powder and the adhesive in a forming machine with an eccentric stirring paddle, wherein a barrel body of the forming machine and the stirring paddle rotate in a reverse direction, so that the molecular sieve powder and the adhesive form an aggregate flow under stirring. The meaning of the eccentric paddle is well known to those skilled in the art and the off-center position may be, for example, the paddle is located from the center at a distance of 1/3-3/4 of the radius of the barrel. The barrel cover matched with the barrel body can ensure the sealing performance in the barrel, meanwhile, materials splashed on the barrel wall are scraped by the scraper and enter the aggregate flow rotating in the barrel again, and the scraper is close to the barrel wall to ensure the achievement of the purpose, for example, the distance can be 2-3 mm. With the continuous reverse rotation, the material forms molecular sieve seed crystals in the forming machine, then spherical particles are further formed, and the microsphere molecular sieve can be obtained after discharging until the granularity of the spherical particles reaches the required range, namely, the purpose of controlling the size of the microspheres of the molecular sieve can be achieved by controlling the time for which the material rotates in the forming machine. The barrel body of the forming machine forms an inclination angle with a certain angle with the vertical direction, so that the microsphere molecular sieve with the required granularity can be obtained quickly, and the inclination angle is further preferably 20-30 degrees. The diameter and the height of the barrel body of the forming machine can be designed according to actual needs.

According to the disclosure, in the step c, the rotating speed of the forming machine and the stirring paddle is adjusted, so that the microsphere molecular sieve with the required granularity can be obtained quickly. For example, the rotating speed of the barrel of the forming machine can be 20-50rpm, and the rotating speed of the stirring paddle can be 200 and 2000 rpm. The respective rotation directions of the stirring paddle and the forming machine are not limited as long as the stirring paddle and the forming machine rotate in opposite directions.

According to the present disclosure, the rotational molding in step c may be performed with an additive added, and the additive may be, for example, at least one selected from 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, and the amount thereof may be adjusted according to actual needs, and generally, the amount of the additive is 1 to 5 wt% based on the dry weight of the molecular sieve. It will be appreciated by those skilled in the art that the additive may have a modifying or pore-expanding effect or may facilitate molding, but it may be completely volatilized during the subsequent calcination process and may not remain on the catalyst, so that the finally prepared catalyst does not contain additive components, depending on the requirements.

According to the disclosure, in step d, the baking of the microspherical molecular sieve is a conventional step in the process of preparing a molecular sieve catalyst, and the conditions may be as follows: the temperature is 200 ℃ and 600 ℃ and the time is 1-20 hours.

According to the present disclosure, in order to provide the catalyst with higher strength and higher catalytic activity, in step d, the calcined microspherical molecular sieve may be contacted with a basic buffer solution containing a nitrogen compound. The basic buffer solution of the nitrogen-containing compound may contain an ammonium salt and a base. The ammonium salt can be water-soluble ammonium salt, for example, at least one of ammonium carbonate, ammonium fluoride, ammonium chloride, ammonium acetate and ammonium nitrate, preferably ammonium acetate and/or ammonium nitrate, and can also be quaternary ammonium salt of C1-C3 alkyl; the alkali may be at least one of ammonia water, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide, and preferably ammonia water. The ratio of the ammonium salt to the base may be any and may be used for the purpose of the present disclosure, and in order to provide the microspheric Silicate-1 molecular sieve catalyst of the present disclosure with higher attrition resistance and higher catalytic activity, the content of the ammonium salt is preferably 0.5 to 20 wt%, and the content of the base is preferably 5 to 30 wt%. The pH value of the alkaline buffer solution of the nitrogen-containing compound is preferably 8.5 to 13.5, and more preferably 9 to 12. The weight ratio of the baked microspherical molecular sieve to the alkaline buffer solution containing the nitrogen compound on a dry basis can be 1: (5-15). The contact temperature may be 50-120 deg.C, and the contact pressure may be 0.5-5kg/cm ²The contact time may be 10 to 300 minutes. The contacting may be carried out in any manner, preferably in a fixed bed reactor or a reaction vessel. The operation of contacting the calcined microspherical molecular sieve with the alkaline buffer solution containing the nitrogen compound may be performed one or more times.

According to the disclosure, after the baked microsphere molecular sieve is contacted with the alkaline buffer solution containing the nitrogen compound, the material after the contact can be washed by deionized water to remove the nitrogen compound on the surface of the microsphere molecular sieve catalyst, and then the filtration and the drying are carried out. The drying is carried out as long as the moisture is sufficiently removed, and the drying method can be heating drying, air-blast drying or natural drying, wherein the drying temperature can be 100-120 ℃, and the drying time can be 10-24 hours. When the catalyst obtained by washing and drying the contacted materials is used for preparing caprolactam from cyclohexanone oxime, the catalyst is favorable for improving the conversion rate of cyclohexanone oxime and the selectivity of caprolactam.

In a third aspect of the present disclosure, there is provided a process for producing caprolactam from cyclohexanone oxime, the process comprising: the cyclohexanone oxime is contacted with the microsphere Silicate-1 molecular sieve catalyst containing trace metal ions provided by the first aspect of the invention in the presence of a solvent to carry out gas-phase Beckmann rearrangement reaction.

According to the present disclosure, the molar ratio of the solvent to cyclohexanone oxime may be (2-10): 1. the solvent may be selected from fatty alcohols of 1-6 carbon atoms, preferably methanol and/or ethanol.

According to the present disclosure, the rearrangement reaction may be carried out in the presence of nitrogen, and the molar ratio of nitrogen to cyclohexanone oxime may be (10-80): 1, preferably (20-40): 1. in addition, a certain amount of NH was bubbled into the nitrogen₃、(CH₃)₃N and other nitrogen-containing basic gases are beneficial to improving the rearrangement performance of the catalyst.

According to the present disclosure, the conditions under which the rearrangement reaction is carried out may be: the weight space velocity (WHSV) of the cyclohexanone oxime is 0.1-20 h^-1Preferably 0.5 to 10 hours^-1(ii) a The reaction temperature is 300-500 ℃, preferably 350-400 ℃, and more preferably 370-390 ℃; the reaction pressure is 0.1-0.5 MPa.

According to the present disclosure, a small amount of water is added to cyclohexanone oxime, which can extend the life of the catalyst, and thus, cyclohexanone oxime and water can be mixed in a molar ratio of 1: (0.01-2.5), and then contacting the mixture with the microsphere Silicate-1 molecular sieve catalyst containing trace metal ions in the presence of the solvent to carry out gas phase Beckmann rearrangement reaction.

When the microsphere Silicate-1 molecular sieve catalyst containing trace metal ions is applied to the cyclohexanone-oxime gas-phase Beckmann rearrangement reaction, the cyclohexanone-oxime conversion rate and the caprolactam selectivity are high, the long-period continuous production of caprolactam can be realized, and the total caprolactam selectivity and the total caprolactam yield are higher than those of the existing Silicate-1 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.

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.

BET specific surface area, external specific surface area data for Silicate-1 molecular sieve samples are generated by an automated adsorption apparatus, model U.S. Micromeritics ASAP-2400, under the following test conditions: n is a radical of hydrogen₂As 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 metal ion content 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 the solid molecular sieve or catalyst with HF acid or aqua regia to make the silicon oxide in the sample volatile, and measuring in water 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 cell phone. 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).

Example 1

416kg of ethyl orthosilicate, 360kg of 22.5 wt% tetrapropylammonium hydroxide (abbreviated as TPAOH), 56.2g of Fe (NO) ₃)₃·9H₂O and 415kg of water were mixed and stirred at room temperature for 5 hours to form a colloidal mixture having a pH of 12.8, in which SiO was present₂：TPAOH：H₂O (molar ratio) ═ 1: 0.2: 20, SiO₂With Fe³⁺The weight ratio of (A) to (B) is 15347: 1, transferring the mixture to a volume of 2m³Crystallizing at 100 deg.C for 3 days in a stainless steel reaction kettle to obtain crystallized product with pH of 13.57, and making into film with 50nm six-tube filmFiltering and washing by adopting water with the temperature of 40-60 ℃, wherein the using amount of the washing water is 6.8m³The pH value of the post-crystallized product reaches 9.1. And concentrating the washed slurry to obtain 395kg of molecular sieve slurry with the solid content of 26.8 weight percent, drying by microwave for 1 hour at 100-150 ℃ to obtain 125kg of Silicate-1 molecular sieve raw powder.

The above Silicate-1 molecular sieve has an iron ion content of 64ppm and a BET specific surface area of 446 m²Per gram, external specific surface 61 m²The grain size is 0.1-0.2 mu m.

And (3) crushing the Silicate-1 molecular sieve raw powder on a crusher by using a 80-mesh screen to obtain a powder sample with 100-250 meshes. Pouring 15kg of 100-250 mesh molecular sieve powder sample into a 40L mechanical strong forming machine (the diameter of a barrel body is 750mm, the inclination angle of the barrel body and the vertical direction is 30 degrees) for rotary forming, rotating the barrel body of the forming machine in the clockwise direction at the rotating speed of 30rpm, rotating an eccentric stirring paddle in the anticlockwise direction at the stirring speed of 1500rpm, and injecting 10.6kg of 30 wt% alkaline silica sol (the pH value is 9.5, the content of sodium ions is 324ppm, and the content of SiO is 5 ppm) from a feed inlet after rotating for 5min ₂Content of 40 wt%, and roasting to obtain SiO₂Has a surface area of 225m²And/g) and uniformly spraying the powder, and rotationally stirring for 60min to obtain about 17kg of microsphere molecular sieve with the granularity of 100-300 mu m and a plurality of kg of other unqualified materials. The microsphere molecular sieve is respectively roasted at 280 ℃, 400 ℃ and 480 ℃ for 2h, and finally roasted at 550 ℃ for 6 h to obtain about 10kg of microsphere molecular sieve, wherein the content of the Silicate-1 molecular sieve containing trace metal 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 85 ℃ and 2.6kg/cm²Stirring for 3 hours under pressureThen filtering, drying at 120 ℃ for 24 hours, repeating the above operation of contacting 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 at 120 ℃ for 24 hours to obtain the microsphere molecular sieve catalyst, No. 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 4.4; 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 at 105-250 μm.

TABLE 1

Particle size (um)	Interval%	Cumulative% of	Particle size (um)	Interval%	Cumulative%	Particle size (um)	Interval%	Cumulative%	Particle size (um)	Interval%	Cumulative%
												0.10-0.11	0	0	0.76-0.85	0	0	5.85-6.51	0	0	44.69-49.74	0	0
0.11-0.12	0	0	0.85-0.95	0	0	6.51-7.24	0	0	49.74-55.36	0	0
												0.12-0.14	0	0	0.95-1.05	0	0	7.24-8.06	0	0	55.36-61.62	0	0
0.14-0.15	0	0	1.05-1.17	0	0	8.06-8.97	0	0	61.62-68.58	0	0
												0.15-0.17	0	0	1.17-1.31	0	0	8.97-9.98	0	0	68.58-76.33	0	0
0.17-0.19	0	0	1.31-1.45	0	0	9.98-11.11	0	0	76.33-84.96	0	0
												0.19-0.21	0	0	1.45-1.62	0	0	11.11-12.37	0	0	84.96-94.56	0	0
0.21-0.24	0	0	1.62-1.80	0	0	12.37-13.77	0	0	94.56-105.24	0	0
												0.24-0.26	0	0	1.80-2.00	0	0	13.77-15.32	0	0	105.24-117.13	2.74	2.74
0.26-0.29	0	0	2.00-2.23	0	0	15.32-17.05	0	0	117.13-130.37	9.76	12.5
												0.29-0.32	0	0	2.23-2.48	0	0	17.05-18.98	0	0	130.37-145.10	16.41	28.91
0.32-0.36	0	0	2.48-2.76	0	0	18.98-21.12	0	0	145.10-161.50	19.71	48.62
												0.36-0.40	0	0	2.76-3.08	0	0	21.12-23.51	0	0	161.50-179.75	20.28	68.9
0.40-0.45	0	0	3.08-3.42	0	0	23.51-26.17	0	0	179.75-200.06	17.6	86.5
												0.45-0.50	0	0	3.42-3.81	0	0	26.17-29.12	0	0	200.06-222.66	10.57	97.07
0.50-0.55	0	0	3.81-4.24	0	0	29.12-32.41	0	0	222.66-247.83	2.93	100
												0.55-0.62	0	0	4.24-4.72	0	0	32.41-36.08	0	0	247.83-275.83	0	100
0.62-0.69	0	0	4.72-5.25	0	0	36.08-40.15	0	0	275.83-307.00	0	100
												0.69-0.76	0	0	5.25-5.85	0	0	40.15-44.69	0	0	307.00-341.69	0	100

Example 2

416kg of ethyl orthosilicate, 360kg of 22.5% by weight tetrapropylammonium hydroxide (abbreviated to TPAOH), 0.236kg of Al (NO)₃)₃·9H₂O and 410kg of water were mixed and stirred at room temperature for 5 hours to form a colloidal mixture having a pH of 12.35, in which SiO was present₂：TPAOH：H₂O (molar ratio) ═ 1: 0.2: 20, SiO₂With Al³⁺The weight ratio of 7067: 1, transferring the mixture to a volume of 2m³Stainless steelCrystallizing at 100 deg.C for 3 days in a kettle to obtain crystallized product with pH of 13.71, filtering with 50nm six-tube membrane, washing with water of 40-60 deg.C (6.6 m)³The pH value of the post-crystallized product reaches 9.0. And concentrating the washed slurry to obtain 310kg of molecular sieve slurry with the solid content of 34.5 wt%, drying by microwave for 1 hour at 100-150 ℃ to obtain 125kg of Silicate-1 molecular sieve raw powder.

The above Silicate-1 molecular sieve has an aluminum ion content of 140ppm and a BET specific surface area of 433 m²Per gram, external specific surface 51 m²The grain size is 0.1-0.2 mu m.

And (3) crushing the Silicate-1 molecular sieve raw powder on a crusher by using a 80-mesh screen to obtain a powder sample with 100-250 meshes. Pouring 15kg of 100-250 mesh molecular sieve powder sample into a 40L mechanical strong forming machine (the diameter of a barrel body is 750mm, the inclination angle of the barrel body and the vertical direction is 30 degrees) for rotary forming, rotating the barrel body of the forming machine along the clockwise direction at the rotating speed of 30rpm, rotating an eccentric stirring paddle along the anticlockwise direction at the stirring speed of 1500rpm, injecting 7.5kg of 30 weight percent alkaline silica sol (the same as that in example 1) from a feed inlet after rotating for 5min, uniformly spraying the alkaline silica sol onto the powder, and rotating and stirring for 60min to obtain about 17kg of microsphere molecular sieve with the granularity of 100-300 mu m and a plurality of kg of other unqualified materials. The microsphere molecular sieve is respectively roasted at 280 ℃, 400 ℃ and 480 ℃ for 2h, and finally roasted at 550 ℃ for 6 h to obtain about 10kg of microsphere molecular sieve, wherein the content of the Silicate-1 molecular sieve containing trace metal ions is 85 weight percent, and the content of the adhesive silica sol is 15 weight percent.

Adding 95g of the microsphere molecular sieve and 950g of a basic buffer solution containing a nitrogen compound (the basic buffer solution containing the nitrogen 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 stainless steel reaction kettle at 90 ℃ and 3.0kg/cm ²Stirring under pressure for 3 hours, filtering, drying at 120 ℃ for 24 hours, and repeating the basic reaction under the same conditionsAnd (3) carrying out contact operation on the buffer solution once, filtering again, washing until the pH of the filtered clear solution is 9, and drying at 120 ℃ for 24 hours to obtain the microsphere molecular sieve catalyst with the number of A2.

The photograph of catalyst a2 is similar to that of fig. 1; the abrasion index K is 4.4; the test results of the particle size distribution showed that the particle size of catalyst A2 was concentrated at 100-300. mu.m.

Example 3

416kg of tetraethoxysilane, 360kg of 22.5 wt% tetrapropylammonium hydroxide (abbreviated as TPAOH), 8.4g of ZrOCl₂·8H₂O and 420kg of water, and stirring the mixture at normal temperature for 5 hours to form a colloidal mixture with the pH value of 12.46, wherein SiO is contained in the colloidal mixture₂：TPAOH：H₂O (molar ratio) ═ 1: 0.2: 20, SiO₂With Zr⁴⁺The weight ratio of (A) to (B) is 50596: 1, transferring the mixture to a volume of 2m³Crystallizing at 100 deg.C for 3 days in a stainless steel reaction kettle to obtain crystallized product with pH of 13.42, filtering with 50nm six-tube membrane, washing with water of 40-60 deg.C (the amount of washing water is 6.7 m)³The pH value of the post-crystallized product reaches 9.1. And concentrating the washed slurry to obtain 310kg of molecular sieve slurry with the solid content of 28.4 wt%, drying by microwave for 1 hour at 100-150 ℃ to obtain about 127kg of Silicate-1 molecular sieve raw powder.

The above Silicate-1 molecular sieve has a zirconium ion content of 20ppm and a BET specific surface area of 428 m²Per gram, external specific surface 48 meters²The grain size is 0.1-0.25 mu m.

And (3) crushing the Silicate-1 molecular sieve raw powder on a crusher by using a 80-mesh screen to obtain a powder sample with 100-250 meshes. Pouring 15kg of 100-250 mesh molecular sieve powder sample into a 40L mechanical strong forming machine (the diameter of a barrel body is 750mm, the inclination angle of the barrel body and the vertical direction is 30 degrees) for rotary forming, rotating the barrel body of the forming machine along the clockwise direction at the rotating speed of 30rpm, rotating an eccentric stirring paddle along the anticlockwise direction at the stirring speed of 1500rpm, injecting 13.4kg of 30 wt% alkaline silica sol (the same as that in example 1) from a feed inlet after rotating for 5min, uniformly spraying the alkaline silica sol onto the powder, and carrying out rotary stirring for 60min to obtain about 17kg of microsphere molecular sieve with the granularity of 100-300 mu m and a plurality of kg of other unqualified materials. The microsphere molecular sieve is respectively roasted at 280 ℃, 400 ℃ and 480 ℃ for 2h, and finally roasted at 550 ℃ for 6 h to obtain about 10kg of microsphere molecular sieve, wherein the content of the Silicate-1 molecular sieve containing trace metal 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 4.0kg/cm ²Stirring for 3 hours under pressure, then filtering, drying for 24 hours at 120 ℃, then repeating the contact operation of the alkaline 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 2.0; the results of the particle size distribution test showed that the particle size of catalyst A3 was concentrated at 100-300. mu.m.

Example 4

416kg of ethyl orthosilicate, 360kg of 22.5% by weight tetrapropylammonium hydroxide (abbreviated as TPAOH), 50.4g of tetrabutyl titanate and 420kg of water were mixed and stirred at normal temperature for 5 hours to form a colloidal mixture having a pH of 12.32, in which SiO was contained₂：TPAOH：H₂O (molar ratio) ═ 1: 0.2: 20, SiO₂With Ti⁴⁺The weight ratio of 169937: 1, transferring the mixture to a volume of 2m³Crystallizing at 100 deg.C for 3 days in a stainless steel reaction kettle to obtain crystallized product with pH of 13.50, filtering with 50nm six-tube membrane, washing with 40-60 deg.C water with washing water amount of 6.8m³The pH value of the post-crystallized product reaches 9. And concentrating the washed slurry to obtain 350kg of molecular sieve slurry with the solid content of 30.7 wt%, drying by microwave for 1 hour at 100-150 ℃ to obtain about 127kg of Silicate-1 molecular sieve raw powder.

The above Silicate is divided into 1The titanium ion content of the sub-sieve was 60ppm, and the BET specific surface area was 451 m²Per gram, external specific surface 58 m²The grain size is 0.1-0.25 mu m.

And (3) crushing the Silicate-1 molecular sieve raw powder on a crusher by using a 80-mesh screen to obtain a powder sample with 100-250 meshes. Pouring 15kg of 100-250 mesh molecular sieve powder sample into a 40L mechanical strong forming machine (the diameter of a barrel body is 750mm, the inclination angle of the barrel body and the vertical direction is 30 degrees) for rotary forming, rotating the barrel body of the forming machine along the clockwise direction at the rotating speed of 30rpm, rotating an eccentric stirring paddle along the anticlockwise direction at the stirring speed of 1500rpm, injecting 10.5kg of 30 wt% alkaline silica sol (the same as that in example 1) from a feed inlet after rotating for 5min, uniformly spraying the alkaline silica sol onto the powder, and rotating and stirring for 60min to obtain about 10kg of microsphere molecular sieve with the granularity of 100-300 mu m and a plurality of kg of other unqualified materials. The microsphere molecular sieve is respectively roasted at 280 ℃, 400 ℃ and 480 ℃ for 2h, and finally roasted at 550 ℃ for 6 h to obtain about 10kg of microsphere molecular sieve, wherein the content of the Silicate-1 molecular sieve containing trace metal 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/cm ²Stirring for 3 hours under pressure, then filtering, drying for 24 hours at 120 ℃, then repeating the contact operation of the alkaline buffer solution of the nitrogen-containing compound once 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 microspherical molecular sieve catalyst with the number of A4.

The photograph of catalyst a4 is similar to that of fig. 1; the abrasion index K is 3.1; the test results of the particle size distribution showed that the particle size of catalyst A4 was concentrated at 100-300. mu.m.

Example 5

208kg of tetraethoxysilane and 360kg of 22.5% tetrapropylammonium hydroxide (abbreviated as TPAOH), 184kg of ethanol, 0.028gCr (NO)₃)₃·9H₂O and 440kg of water were mixed and stirred at room temperature for 5 hours to form a colloidal mixture having a pH of 12.94 and SiO in the mixture₂：TPAOH：H₂O (molar ratio) ═ 1: 0.4: 40, ethanol: SiO 2₂(molar ratio) 8, SiO₂And Cr³⁺The weight ratio of (A) to (B) is 16483: 1, transferring the mixture to a volume of 2m³Crystallizing at 100 deg.C for 3 days in a stainless steel reaction kettle to obtain crystallized product with pH of 13.50, filtering with 50nm six-tube membrane, washing with water of 40-60 deg.C (7 m)³The pH value of the post-crystallized product reaches 9. And concentrating the washed slurry to obtain 160kg of molecular sieve slurry with the solid content of 34.1 wt%, drying by microwave for 1 hour at 100-150 ℃ to obtain 125kg of Silicate-1 molecular sieve raw powder.

The Silicate-1 molecular sieve has a chromium ion content of 60ppm and a BET specific surface area of 433 m²Per gram, external specific surface 52 m²The grain size is 0.1-0.3 mu m.

And (3) crushing the Silicate-1 molecular sieve raw powder on a crusher by using a 80-mesh screen to obtain a powder sample with 100-250 meshes. Pouring 15kg of 100-250 mesh molecular sieve powder sample into a 40L mechanical strong forming machine (the diameter of a barrel body is 750mm, the inclination angle of the barrel body and the vertical direction is 30 degrees) for rotary forming, rotating the barrel body of the forming machine along the clockwise direction, rotating at 30rpm, rotating an eccentric stirring paddle along the counterclockwise direction, stirring at 1500rpm, injecting 4.8kg of 30 wt% alkaline silica sol (the same as that in example 1) from a feed inlet after rotating for 5min, uniformly spraying the alkaline silica sol onto the powder, and rotating and stirring for 60min to obtain about 8kg of microsphere molecular sieve with the granularity of 100-300 mu m and a plurality of kg of other unqualified materials. The microsphere molecular sieve is respectively roasted at 280 ℃, 400 ℃ and 480 ℃ for 2h, and finally roasted at 550 ℃ for 6 h to obtain about 10.4kg of the microsphere molecular sieve, wherein the content of the Silicate-1 molecular sieve containing trace metal ions is 90 wt%, and the content of the adhesive silica sol is 10 wt%.

Mixing 100g of the above microsphere molecular sieve with 1000g of a basic buffer solution containing a nitrogen compound The alkaline buffer solution of the compound 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 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 is 3: 2, pH value 11.4) was added to a 2L stainless steel reaction vessel at 80 ℃ and 2.0kg/cm²Stirring for 3 hours under pressure, then filtering, drying for 24 hours at 120 ℃, then repeating the contact operation of the alkaline buffer solution of the nitrogen-containing compound once 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 microspherical molecular sieve catalyst with the number of A5.

The photograph of catalyst a5 is similar to that of fig. 1; the abrasion index K is 7.5; the test results of the particle size distribution showed that the particle size of catalyst A5 was concentrated at 100-300. mu.m.

Example 6

416kg of ethyl orthosilicate, 360kg of 22.5 wt% tetrapropylammonium hydroxide (abbreviated as TPAOH), 56.2g of Fe (NO)₃)₃·9H₂O and 415kg of water were mixed and stirred at room temperature for 5 hours to form a colloidal mixture having a pH of 12.8, in which SiO was present₂：TPAOH：H₂O (molar ratio) ═ 1: 0.2: 20, SiO₂With Fe³⁺The weight ratio of (A) to (B) is 15347: 1, transferring the mixture to a volume of 2m³Crystallizing at 100 deg.C for 3 days in a stainless steel reaction kettle to obtain crystallized product with pH of 13.57, filtering with 50nm six-tube membrane, washing with water of 40-60 deg.C (the amount of washing water is 6.8 m) ³The pH value of the post-crystallized product reaches 9.1. And concentrating the washed slurry to obtain 395kg of molecular sieve slurry with the solid content of 26.8 weight percent, drying by microwave for 1 hour at 100-150 ℃ to obtain about 120kg of Silicate-1 molecular sieve raw powder.

The above Silicate-1 molecular sieve has an iron ion content of 64ppm and a BET specific surface area of 444 m²Per gram, external specific surface 60m²The grain size is 0.1-0.2 mu m.

And (3) crushing the Silicate-1 molecular sieve raw powder on a crusher by using a 80-mesh screen to obtain a powder sample with 100-250 meshes. Pouring 15kg of 100-250 mesh molecular sieve powder sample into a 40L mechanical strong forming machine (the diameter of a barrel body is 750mm, the inclination angle of the barrel body and the vertical direction is 30 degrees) for rotary forming, rotating the barrel body of the forming machine along the clockwise direction at the rotating speed of 30rpm, rotating an eccentric stirring paddle along the anticlockwise direction at the stirring speed of 1500rpm, injecting 10.6kg of 30 weight percent alkaline silica sol (the same as that in example 1) from a feed inlet after rotating for 5min, uniformly spraying the alkaline silica sol onto the powder, and carrying out rotary stirring for 60min to obtain about 17kg of microsphere molecular sieve with the granularity of 100-300 mu m and a plurality of kg of other unqualified materials. The microsphere molecular sieve is respectively roasted at 280 ℃, 400 ℃ and 480 ℃ for 2h, and finally roasted at 550 ℃ for 6 h to obtain about 10kg of microsphere molecular sieve, wherein the content of the Silicate-1 molecular sieve containing trace metal ions is 80 wt%, and the content of the adhesive silica sol is 20 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 82 ℃ and 2.3kg/cm²Stirring for 3 hours under pressure, then filtering, drying for 24 hours at 120 ℃, then repeating the contact operation of the alkaline buffer solution of the nitrogen-containing compound once 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 microspherical molecular sieve catalyst with the number of A6.

The photograph of catalyst a6 is similar to that of fig. 1; the abrasion index K is 5.0; the test results of the particle size distribution showed that the particle size of catalyst A6 was concentrated at 100-300. mu.m.

From the results of examples 1-6, it can be seen that the microspherical Silicate-1 molecular sieve catalyst containing trace metal ions of the present disclosure has a low attrition index, and thus can be used in a fluidized bed process for preparing caprolactam by gas phase beckmann rearrangement of cyclohexanone oxime.

Test examples

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

The cyclohexanone oxime gas phase Beckmann rearrangement reaction is carried out by using the 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 enters a collecting bottle for gas-liquid separation after being cooled by an ice-water mixture, and the composition analysis of the product is carried out after the reaction is carried out for 7 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 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 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% for caprolactam mol% (caprolactam mol%) in the reaction product/(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 1

As can be seen from Table 1, the microsphere Silicate-1 molecular sieve catalyst containing trace metal ions prepared by the method has high cyclohexanone oxime conversion rate when the weight space velocity (WHSV) of cyclohexanone oxime is 16h ^-1Then, the reaction time can reach 99.25% at most after 7 hours, and the selectivity to caprolactam is high, and can reach 96.76% at most.

The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. A microsphere Silicate-1 molecular sieve catalyst containing trace metal ions is characterized by comprising 70-95 wt% of a Silicate-1 molecular sieve containing trace metal ions and 5-30 wt% of a binder, wherein the weight of the dry basis of the catalyst is taken as a reference; the particle size of the catalyst is 20-300 mu m, and the abrasion index K is less than 8;

The BET specific surface area of the Silicate-1 molecular sieve is 400-500 m²The weight ratio of the silicon oxide to the metal ions is (5000-;

the Silicate-1 molecular sieve containing trace metal ions is formed in a rotary forming mode;

the rotary forming is carried out in a forming machine with an eccentric stirring paddle, a barrel body of the forming machine can rotate reversely with the stirring paddle, the forming machine is provided with a barrel cover matched with the barrel body, a scraper facing the barrel wall is arranged on the barrel cover and facing the interior of the barrel body and used for scraping materials splashed on the barrel wall in the rotary forming process, and the barrel body of the forming machine forms an inclination angle of 20-40 degrees with the vertical direction.

2. The catalyst of claim 1, wherein the catalyst comprises 80 to 90 wt% of the Silicate-1 molecular sieve, and 10 to 20 wt% of the binder, based on the dry weight of the catalyst;

3. The catalyst of claim 1 or 2, wherein the metal ion is selected from Co²⁺、Ni²⁺、Cu²⁺、Zn²⁺、Fe²⁺、Mn²⁺、Cr³⁺、Fe³⁺、Ga³⁺、Al³⁺、Ti⁴⁺、Zr⁴⁺、Sn⁴⁺、Ge⁴⁺、Pb⁴⁺、Mn⁴⁺、V⁵⁺、Sb⁵⁺、Mn⁶⁺、Mo⁶⁺And W⁶⁺At least one of;

the adhesive is silica sol, the sodium ion content of the silica sol is 10-500ppm, and SiO is ₂The content is 20-45 wt%.

4. A method of preparing the microspheroidal Silicate-1 molecular sieve catalyst containing trace metal ions of any one of claims 1 to 3, which comprises:

a. mixing a silicon source, a metal ion source, an organic template and water to obtain a colloid mixture, wherein SiO in the colloid mixture is calculated according to molar ratio₂Organic template agent H₂1 to (0.05-0.50) to (5-100), and the weight ratio of the silicon oxide to the metal ions is (5000-;

5. The method according to claim 4, wherein 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 at least one selected from fatty amine compounds, alcohol amine compounds and quaternary ammonium base compounds.

6. The method of claim 5, wherein the silicon source is of the formula (OR)¹)₄Organosilicate of Si wherein R¹Is an alkyl group of 1 to 4 carbon atoms.

7. The method of claim 6, wherein the silicon source is methyl orthosilicate and/or ethyl orthosilicate.

8. The method of claim 5, wherein the organic templating agent is an alkyl quaternary ammonium base compound having 1-4 carbon atoms.

9. The method of claim 8, wherein the organic templating agent is tetraethylammonium hydroxide and/or tetrapropylammonium hydroxide.

10. The method of claim 4, wherein the colloidal mixture of step a further comprises a lower alcohol, the lower alcohol being in contact with SiO₂The molar ratio of the low carbon alcohol to the alcohol is 1 to (4-15), and the low carbon alcohol is methanol and/or ethanol.

11. The method as claimed in claim 4, wherein in step c, the barrel of the forming machine is rotated at 20-50rpm, and the rotation speed of the stirring paddle is 200-2000 rpm.

12. The method of claim 4, wherein the firing conditions in step d are: the temperature is 200 ℃ and 600 ℃ and the time is 1-20 hours.

13. The method according to claim 4, wherein in the step d, the alkaline buffer solution containing the nitrogen-containing compound contains ammonium salt and alkali, the content of the ammonium salt is 0.5-20 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.

14. The method of claim 4, wherein in the step d, the weight ratio of the baked microsphere molecular sieve to the basic 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 10-300 minutes.

15. A process for producing caprolactam from cyclohexanone oxime, the process comprising: contacting cyclohexanone oxime with the microsphere Silicate-1 molecular sieve catalyst containing trace metal ions, which is disclosed in any one of claims 1 to 3, in the presence of a solvent to perform a vapor phase Beckmann rearrangement reaction.

16. The process according to claim 15, wherein the molar ratio of the solvent to cyclohexanone oxime is (2-10): 1;

the solvent is selected from C1-C6 fatty alcohol.

17. The method of claim 16, wherein the solvent is methanol and/or ethanol.

18. The process according to claim 15, wherein the rearrangement reaction is carried out in the presence of nitrogen in a molar ratio of nitrogen to cyclohexanone oxime of (10-80) to 1.

19. The method of claim 15, wherein the rearrangement reaction is carried out under conditions that: 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.

20. The process of claim 15, further comprising mixing cyclohexanone oxime with water in a molar ratio of 1: 0.01 to 2.5, and then contacting the mixture with the microsphere Silicate-1 molecular sieve catalyst containing trace metal ions in the presence of the solvent to perform a vapor phase beckmann rearrangement reaction.