A gas-phase Beckmann rearrangement method

Abstract

A gas-phase Beckmann rearrangement method involves contacting cyclohexanone oxime with Silicate-1 molecular sieve in the presence of nitrogen and a solvent under rearrangement reaction conditions. It is characterized in that the Silicate-1 molecular sieve contains metal, A HB : A ISO is (15 - 50):1, A HB and A ISO respectively represent the peak intensities at a wavenumber of 3400 cm ‑1 and at a wavenumber of 3725 cm ‑1 in the infrared hydroxyl spectrum of the Silicate-1 molecular sieve, expressed as peak area. The method provided by the present invention can reduce the content of ethyl-ε-caprolactam in by-products, improve the conversion rate of cyclohexanone oxime and the selectivity of caprolactam, enhance the catalyst stability and extend its lifespan.

Description

Technical Field

[0001] The present invention relates to a gas-phase Beckmann rearrangement method, and more particularly to a method for preparing caprolactam by gas-phase Beckmann rearrangement reaction of cyclohexanone oxime using a metal-containing Silicate-1 molecular sieve as a catalyst. Background Art

[0002] More than 90% of the caprolactam production processes are obtained through the Beckmann rearrangement reaction of cyclohexanone oxime. The gas-phase Beckmann rearrangement reaction using a solid acid as a catalyst is a process to achieve sulfur-ammonium-free production of caprolactam. It has the advantages of no environmental pollution, no equipment corrosion, and no by-product of low-value ammonium sulfate, and the separation and purification of the product are also simplified. Therefore, the gas-phase Beckmann rearrangement reaction process has attracted great attention in the industry.

[0003] There are various solid catalysts applied to the gas-phase Beckmann rearrangement reaction. For example, the silica-alumina catalyst used in GB881927; the solid sulfuric acid catalyst used in GB881956; the niobic acid-containing catalyst used in GB1178057; the high-silica-alumina MFI-structured molecular sieve catalyst used in CN269360A, etc. Among them, the MFI-type molecular sieve with a high silica-alumina ratio, especially the all-silica Silicate-1 molecular sieve, has the most prominent performance.

[0004] US4717769 reported that an MFI-type molecular sieve with a high silica-alumina ratio (>500) was used as a catalyst for the gas-solid phase rearrangement reaction of cyclohexanone oxime. At a weight hourly space velocity of 11.7 h -1 , after reacting for 15.3 hours, the conversion rate was still 100%, but its selectivity was very low (83.5%).

[0005] US6303099 reported that a molecular sieve powder with a high silica-alumina ratio was treated with a nitrogen-containing base and used as a catalyst. At a weight hourly space velocity of 8 h -1 , after reacting for 5.5 hours, the conversion rate was 99.5% and the selectivity was 96.2%, but no conversion rate and selectivity data for a longer time were provided.

[0006] CN1883803A reported that pure silicon and high-silica-alumina molecular sieves were treated with hydrofluoric acid. At a reaction temperature of 370 °C, normal pressure, a space velocity of 8 h -1 , and a carrier gas flow rate of 60 ml / min, after reacting for 20 hours, the conversion rate was 98.3% and the selectivity was 98.5%.

[0007] When the all-silica Silicate-1 molecular sieve or the metal-containing Silicate-1 molecular sieve prepared by the prior art is used as the gas-phase rearrangement catalyst, a post-treatment process is required to obtain a relatively high conversion rate of cyclohexanone oxime and selectivity for caprolactam. The conversion rate and selectivity reach 98% and 95% respectively at the 6th hour of rapid evaluation, which basically reaches the limit. However, with the extension of the reaction time, it is difficult to ensure the catalyst stability and service life. In industrial production, the post-treatment process increases energy consumption, material consumption, and waste liquid discharge. Recycling the collected post-treatment liquid can only reduce part of the production load.

[0008] So far, there has been no report on the gas-phase Beckmann rearrangement reaction that can reach the performance indicators of a cyclohexanone oxime conversion rate greater than 99.5% and a caprolactam selectivity greater than 96.5% after 600 h of reaction without a post-treatment process. Summary of the Invention

[0009] The object of the present invention is to provide a gas-phase Beckmann rearrangement method for cyclohexanone oxime, which has the characteristics of higher conversion rate of cyclohexanone oxime and selectivity for caprolactam, less by-product content, and better stability, aiming at the problems of low conversion rate of cyclohexanone oxime and selectivity for caprolactam and poor stability existing in the prior art.

[0010] To achieve the above object, the present invention provides a gas-phase Beckmann rearrangement method, in which cyclohexanone oxime is contacted with a Silicate-1 molecular sieve in the presence of nitrogen and a solvent under rearrangement reaction conditions. It is characterized in that the Silicate-1 molecular sieve contains metal, and A HB : A ISO is (15 - 50):1, and A HB and A ISO respectively represent the peak intensities at the wave numbers of 3400 cm -1 and 3725 cm -1 in the infrared hydroxyl spectrum of the Silicate-1 molecular sieve, expressed in terms of peak area.

[0011] The peak at the wave number of 3400 cm -1 (the highest value) in the infrared hydroxyl spectrum represents the hydrogen-bonded silanol groups in the Silicate-1 molecular sieve; the peak at the wave number of 3725 cm -1 (the highest value) in the infrared spectrum represents the isolated silanol groups in the Silicate-1 molecular sieve. The Silicate-1 molecular sieve of the present invention has a higher proportion of hydrogen-bonded silanol groups. Increasing A HB : A ISO can effectively reduce the occurrence of various side reactions and help improve the selectivity of the target product. Optionally, A HB : A ISO is (15 - 25):1. The infrared hydroxyl spectrum is obtained by Fourier transform infrared spectroscopy.

[0012] The described Silicate-1 molecular sieve, wherein the metal is preferably at least one metal element selected from transition metal elements, Group IIIA elements, and Group IVA elements. The metal is further preferably at least one of Group IVB elements and Group VB elements. The metal is most preferably at least one of Ti, Nb, Ta, Ga, La, Ge, Sn, and Pb elements.

[0013] The described Silicate-1 molecular sieve, wherein the content of the metal, based on the dry weight of the Silicate-1 molecular sieve, is 10 - 5000 ppm, preferably 15 - 4000 ppm, further preferably 50 - 800 ppm, and more preferably 200 - 500 ppm.

[0014] The described Silicate-1 molecular sieve has a BET specific surface area of 300 - 500 m 2 / g, preferably 350 - 500 m 2 / g, more preferably 440 - 480 m 2 / g; the external specific surface area is 20 - 100 m 2 / g, preferably 20 - 80 m 2 / g, more preferably 50 - 85 m 2 / g, most preferably 55 - 75 m 2 / g; the particle size is 0.01 - 1 μm, preferably 0.1 - 0.3 μm, more preferably 0.15 - 0.3 μm; the relative crystallinity is 70% - 110%. The preferred relative crystallinity is 80% - 90%.

[0015] The preparation method of the described metal-containing Silicate-1 molecular sieve is characterized by including mixing a silicon source, a metal source, a fluorine-containing compound, an organic template agent, and water to obtain a colloidal mixture; subjecting the colloidal mixture to hydrothermal crystallization to obtain a crystallization product; washing, filtering, drying, and calcining the crystallization product; wherein the molar ratio of the silicon source: the fluorine-containing compound: the organic template agent: water is 1:(0.01 - 0.50):(0.05 - 0.50):(5 - 100); the weight ratio of the silicon source: the metal source is (100 - 100000):1; the silicon source is calculated as SiO2, and the metal source is calculated as metal elements.

[0016] Optionally, the silicon source is selected from at least one of silica gel, silica sol, and organic silicate esters. Preferably, the organic silicate ester is methyl orthosilicate and / or ethyl orthosilicate.

[0017] Optionally, the metal source is a water-soluble compound or an oil-soluble compound containing metal ions. Preferably, the metal source is at least one of inorganic salts containing metals, metal alcohol compounds, and metal ester compounds. For example, the metal source can be TiCl4, NbCl5, C 10 H 30 O5Ta, Ga(NO3)3, La(NO3)3, GeCl4.

[0018] Optionally, the organic template agent is at least one selected from aliphatic amine compounds, alkanolamine compounds, and quaternary amine base compounds. The organic template agent is preferably an alkyl quaternary ammonium base compound having 1 to 4 carbon atoms. More preferably, the alkyl quaternary ammonium base compound is tetraethylammonium hydroxide and / or tetrapropylammonium hydroxide.

[0019] Optionally, the fluorine-containing compound is selected from water-soluble compounds or oil-soluble compounds containing fluorine. Preferably, the fluorine-containing compound is at least one of hydrofluoric acid, ammonium fluoride, boron fluoride, and fluorosilicic acid.

[0020] Optionally, the order of material mixing is as follows: Add the metal source to the silicon source. After it is completely dissolved, add the organic template agent and water, and carry out the hydrolysis process at room temperature for 6 to 12 h. After complete hydrolysis, carry out alcohol removal at a temperature of 50 to 90 °C for 12 to 48 h. Finally, add the fluorine-containing compound and mix evenly to obtain a colloidal mixture. The above material mixing order helps to obtain a homogeneous crystallization mother liquor and avoid two-phase stratification.

[0021] Optionally, for the hydrothermal crystallization, the conditions are crystallization at a temperature of 80 to 170 °C for 20 to 100 h. Preferably, the crystallization is carried out at a temperature of 100 to 150 °C for 40 to 60 h. The hydrothermal crystallization can be carried out in a device conventionally selected in the art, such as a hydrothermal reaction kettle.

[0022] Optionally, the drying is carried out at 80 to 120 °C for 12 to 36 h; the conditions for the calcination treatment include: the calcination temperature is 400 to 600 °C and the time is 4 to 12 h. Preferably, the calcination temperature is 450 to 550 °C and the time is 6 to 10 h. The calcination can be carried out in a device conventionally selected in the art, such as a muffle furnace.

[0023] For the gas-phase Beckmann rearrangement of the present invention, a metal-containing Silicate-1 molecular sieve is used as the catalyst, which has a special A HB : A ISOProportion relationship, with a high proportion of hydrogen-bonded silanol groups. The hydrogen-bonded silanol groups in Silicate-1 molecular sieve are the main active centers for the gas-phase Beckmann rearrangement reaction, while doping with trace amounts of metals can serve as Lewis acid centers, which is beneficial to improving the stability of the molecular sieve catalyst and changing the by-product content distribution. The gas-phase Beckmann rearrangement reaction method of cyclohexanone oxime in the present invention can obtain higher cyclohexanone oxime conversion rate and caprolactam selectivity. Detailed implementation manners

[0024] The following provides a detailed description of the specific implementation manners of the present invention. It should be understood that the specific implementation manners described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0025] In the following examples, the composition of the catalyst was determined by X-ray fluorescence spectrometry. The instrument manufacturer is Rigaku Corporation of Japan, model 3031, and the test conditions are tungsten target, excitation voltage 40 kV, and excitation current 50 mA.

[0026] The structure of the catalyst was determined by X-ray diffraction spectrometry. The instrument manufacturer is PANalytical B.V. of the Netherlands, model X′PertPRO, and the test conditions are Cu K radiation, Ni filter, power 40 kV 40 mA, and scanning range 2θ = 5° to 35°.

[0027] In the examples, the BET specific surface area and external specific surface area data of the metal-containing molecular sieve samples were measured by an ASAP-2020 automatic sorptometer of Micromeritics, USA. The test conditions were as follows: N2 was used as the adsorbate, the adsorption temperature was -196.2 °C, and the sample was degassed at a constant temperature of 300 °C and 1.3 Pa for 6 h.

[0028] Infrared hydroxyl group characterization was carried out on a TENSOR II Fourier transform infrared spectrometer of Bruker. The self-supporting sample wafer was treated at 400 °C for 2 h and then cooled to room temperature for scanning.

[0029] In the following examples, unless otherwise specified, the reagents used were all commercially available reagents.

[0030] In the following examples and comparative examples, unless otherwise specified, the pressure was gauge pressure.

[0031] Examples 1-6 and Comparative Examples 1-2 illustrate the preparation and characterization of molecular sieves.

[0032] Example 1

[0033] (1) 0.06 g of C 10 H 30 O5Ta was added to 100 g of tetraethyl orthosilicate. After complete dissolution, 120 g of 25 wt% tetrapropylammonium hydroxide and 150 g of water were added and mixed, and stirred at room temperature for 8 h to form a homogeneous colloidal mixture;

[0034] (2) Ethanol was removed at a temperature of 85 °C (water was continuously added during the process to maintain the material at a certain liquid level), for 20 h, and finally 2.7 g of ammonium fluoride was added to obtain a crystallization mother liquor. The molar ratio of the mixture was SiO2∶NH4F∶TPAOH∶H2O = 1∶0.15∶0.3∶17, and the mass ratio of SiO2 to Ta 5+ was 1090∶1;

[0035] (3) The above mixture was transferred into a 2 L autoclave with a polytetrafluoroethylene liner, hydrothermally crystallized at 120 °C for 60 h, washed, filtered, dried at 120 °C for 24 h, and finally calcined at 550 °C for 6 h to obtain molecular sieve A1.

[0036] The specific physical and chemical properties of the A1 sample are listed in Table 1. The relative crystallinity in the table was determined based on the MFI-structured molecular sieve recorded in "Microporous Materials, Vol 22, p637, 1998" as a standard sample with 100% crystallinity.

[0037] Example 2

[0038] (1) 0.12 g of C 10 H 30 O5Ta was added to 100 g of tetraethyl orthosilicate. After complete dissolution, 120 g of 25 wt% tetrapropylammonium hydroxide and 150 g of water were added and mixed, and stirred at room temperature for 8 h to form a homogeneous colloidal mixture;

[0039] (2) Ethanol was removed at a temperature of 85 °C (water was continuously added during the process to maintain the material at a certain liquid level), for 20 h, and finally 2.7 g of ammonium fluoride was added to obtain a crystallization mother liquor. The molar ratio of the mixture was SiO2∶NH4F∶TPAOH∶H2O = 1∶0.15∶0.3∶17, and the mass ratio of SiO2 to Ta 5+ was 545∶1;

[0040] (3) The above mixture was transferred into a 2 L autoclave with a polytetrafluoroethylene liner, hydrothermally crystallized at 120 °C for 60 h, washed, filtered, dried at 120 °C for 24 h, and finally calcined at 550 °C for 6 h to obtain molecular sieve A2.

[0041] The specific physical and chemical properties of the A2 sample are listed in Table 1.

[0042] Example 3

[0043] (1) 0.06 g of C 10 H 30O5Ta. After complete dissolution, 120 g of 25 wt% tetrapropylammonium hydroxide and 150 g of water were added and mixed, and stirred at room temperature for 8 h to form a homogeneous colloidal mixture;

[0044] (2) Ethanol was removed at 85 °C (water was continuously added during the process to maintain the material at a certain liquid level), for 20 h, and finally 3.6 g of ammonium fluoride was added to obtain a crystallization mother liquor. The molar ratio of the mixture was SiO2∶NH4F∶TPAOH∶H2O = 1∶0.2∶0.3∶17, and the mass ratio of SiO2 to Ta 5+ was 1090∶1;

[0045] (3) The above mixture was transferred into a 2 L autoclave with a polytetrafluoroethylene liner, hydrothermally crystallized at 120 °C for 60 h, washed, filtered, dried at 120 °C for 24 h, and finally calcined at 550 °C for 6 h to obtain molecular sieve A3.

[0046] The specific physicochemical properties of the A3 sample are listed in Table 1.

[0047] Example 4

[0048] (1) 0.12 g of C 10 H 30 O5Ta was added to 100 g of tetraethyl orthosilicate. After complete dissolution, 120 g of 25 wt% tetrapropylammonium hydroxide and 150 g of water were added and mixed, and stirred at room temperature for 8 h to form a homogeneous colloidal mixture;

[0049] (2) Ethanol was removed at 85 °C (water was continuously added during the process to maintain the material at a certain liquid level), for 20 h, and finally 3.6 g of ammonium fluoride was added to obtain a crystallization mother liquor. The molar ratio of the mixture was SiO2∶NH4F∶TPAOH∶H2O = 1∶0.2∶0.3∶17, and the mass ratio of SiO2 to Ta 5+ was 545∶1;

[0050] (3) The above mixture was transferred into a 2 L autoclave with a polytetrafluoroethylene liner, hydrothermally crystallized at 120 °C for 60 h, washed, filtered, dried at 120 °C for 24 h, and finally calcined at 550 °C for 6 h to obtain molecular sieve A4.

[0051] (4) The specific physicochemical properties of the A4 sample are listed in Table 1.

[0052] Example 5

[0053] (1) 0.06 g of C 10 H 30 O5Ta was added to 100 g of tetraethyl orthosilicate. After complete dissolution, 120 g of 25 wt% tetrapropylammonium hydroxide and 150 g of water were added and mixed, and stirred at room temperature for 8 h to form a homogeneous colloidal mixture;

[0054] (2) The ethanol was removed at a temperature of 85 °C (water was continuously added during the process to maintain the material at a certain liquid level), for 20 h, and finally 3.65 g of 40 wt% hydrofluoric acid was added to obtain the crystallization mother liquor. The molar ratio of the mixture was SiO2∶HF∶TPAOH∶H2O = 1∶0.15∶0.3∶17, and the mass ratio of SiO2 to Ta 5+ was 1090∶1;

[0055] (3) The above mixture was transferred into a 2 L autoclave with a polytetrafluoroethylene liner, hydrothermally crystallized at 120 °C for 60 h, washed, filtered, dried at 120 °C for 24 h, and finally calcined at 550 °C for 6 h to obtain molecular sieve A5.

[0056] The specific physical and chemical properties of the A5 sample are listed in Table 1.

[0057] Example 6

[0058] (1) 0.12 g of C 10 H 30 O5Ta was added to 100 g of tetraethyl orthosilicate. After complete dissolution, 120 g of 25 wt% tetrapropylammonium hydroxide and 150 g of water were added and mixed, and stirred at room temperature for 8 h to form a homogeneous colloidal mixture;

[0059] (2) The ethanol was removed at a temperature of 85 °C (water was continuously added during the process to maintain the material at a certain liquid level), for 20 h, and finally 3.65 g of 40 wt% hydrofluoric acid was added to obtain the crystallization mother liquor. The molar ratio of the mixture was SiO2∶HF∶TPAOH∶H2O = 1∶0.15∶0.3∶17, and the mass ratio of SiO2 to Ta 5+ was 545∶1;

[0060] (3) The above mixture was transferred into a 2 L autoclave with a polytetrafluoroethylene liner, hydrothermally crystallized at 120 °C for 60 h, washed, filtered, dried at 120 °C for 24 h, and finally calcined at 550 °C for 6 h to obtain molecular sieve A6.

[0061] The specific physical and chemical properties of the A6 sample are listed in Table 1.

[0062] Comparative Example 1

[0063] In this comparative example, the Silicate-1 molecular sieve catalyst was synthesized according to the method of Chinese Patent CN103896839A. 100 g of tetraethyl orthosilicate, 120 g of 25 wt% tetrapropylammonium hydroxide, and 150 g of water were mixed and stirred at room temperature for 4 h to form a colloidal mixture. The molar ratio of the mixture was SiO2∶TPAOH∶H2O = 1∶0.3∶17. The above mixture was transferred into a 2 L reaction kettle with a polytetrafluoroethylene lining and hydrothermally crystallized at 120 °C for 60 h, washed, filtered, dried at 120 °C for 24 h, and finally calcined at 550 °C for 6 h. The molecular sieve and the basic solution of the nitrogen-containing compound were added to a pressure reaction kettle and stirred at 80 °C for 1 h, washed, filtered, and dried to obtain the comparative molecular sieve numbered D1.

[0064] The specific physical and chemical properties of Sample D1 are listed in Table 1.

[0065] Comparative Example 2

[0066] The same preparation method as in Example 1 was used, and the difference from Example 1 was only that: no fluorine-containing compound was added. The obtained product was denoted as Sample D2.

[0067] The specific physical and chemical properties of Sample D2 are listed in Table 1.

[0068] Table 1

[0069]

[0070] Examples 7 - 12

[0071] Examples 7 - 12 respectively illustrate the catalytic reaction results of the Silicate-1 molecular sieves prepared in Examples 1 - 6 in the gas-phase Beckmann rearrangement reaction.

[0072] Test conditions: The reaction device was an atmospheric pressure continuous flow fixed bed, the inner diameter of the reactor was 5 mm, the loading amount of the catalyst was 0.375 g, about 30 mm high 30-mesh coarse quartz sand was filled above the catalyst bed layer, and 50-mesh fine quartz sand was filled below the catalyst bed layer. The catalyst particle size was 20 - 60 mesh. After the molecular sieves (A1 - A6 and D1 - D2) were loaded into the reaction tube, they were pretreated in a nitrogen atmosphere at atmospheric pressure and 350 °C for 1 h. The concentration of the raw material cyclohexanone oxime was 35%, and the weight hourly space velocity (WHSV) was 16 h -1 , the solvent was ethanol, the reaction temperature was 380 °C, the reaction pressure was 0.1 MPa, the nitrogen flow rate was 45 ml / min, the reaction product was cooled by an ice-water mixture and then entered the collection bottle for gas-liquid separation, and the reaction time was 6 h for product composition analysis.

[0073] The reaction stability evaluation test was carried out on an 80 mL rearrangement device, the concentration of the raw material cyclohexanone oxime was 35%, and the weight hourly space velocity (WHSV) was 1 h -1, the catalyst loading was 30.0 g, the solvent was ethanol, the reaction temperature was 380 °C, the reaction pressure was 0.1 MPa, the nitrogen flow rate was 6.0 L / (h·g), and the reaction product was obtained after 600 h and its composition was analyzed.

[0074] The reaction products were quantitatively analyzed using an Agilent 6890 gas chromatograph (hydrogen flame ionization detector, PEG20M capillary chromatographic column, column length 50 m). The vaporization chamber temperature was 250 °C, the detection chamber temperature was 240 °C, and the column temperature was programmed. It was held at 110 °C for 8 minutes, then increased to 230 °C at a rate of 15 °C / min and held at 230 °C for 14 minutes. The content of the rearrangement products of caprolactam and cyclohexenone after the reaction was calculated by the area normalization method, and the solvent was not involved in the integration.

[0075] Through the above analysis, the molar percentage content of cyclohexanone oxime in the reaction product and the molar percentage content of caprolactam in the reaction product were obtained, and the conversion rate of cyclohexanone oxime and the selectivity of caprolactam were calculated according to the following formulas.

[0076] The results of the reaction for 6 h are shown in Table 2. Note: CPL represents caprolactam; AEH represents ethyl-ε-caprolactim condensate.

[0077] The results of the reaction for 600 h are shown in Table 3.

[0078] Conversion rate of cyclohexanone oxime (mol%) = (100 - molar percentage content of cyclohexanone oxime in the reaction product) / 100 × 100%.

[0079] Selectivity of caprolactam (mol%) = molar percentage content of caprolactam in the reaction product / (100 - molar percentage content of cyclohexanone oxime in the reaction product) × 100%.

[0080] Selectivity of AEH (mol%) = molar percentage content of ethyl-ε-caprolactim condensate in the reaction product.

[0081] Comparative Examples 3 - 4

[0082] Comparative Examples 3 and 4 respectively illustrate the catalytic reaction results of the Silicate-1 molecular sieves prepared in Comparative Examples 1 - 2 in the gas-phase Beckmann rearrangement reaction.

[0083] The test conditions were the same as those in Example 7.

[0084] Examples 13 - 15

[0085] Examples 13 - 15 illustrate the catalytic reaction results of the Silicate-1 molecular sieve prepared in Example 1 in the gas-phase Beckmann rearrangement reaction.

[0086] The test conditions were the same as those in Example 7, except that the weight hourly space velocity (WHSV) of cyclohexanone oxime as the raw material in Examples 13 - 15 was 1 h -1 , 8 h -1 , 12 h -1 respectively, and the corresponding reaction temperatures were 320 °C, 450 °C, and 480 °C.

[0087] Table 2

[0088]

[0089] Table 3

[0090]

[0091] It can be seen from the results in Table 2 and Table 3 that the molecular sieve synthesized by the preparation method provided by the present invention has better catalytic performance. In the gas-phase Beckmann rearrangement reaction of cyclohexanone oxime, the conversion rate of cyclohexanone oxime is higher, up to more than 99.9%, and it is still higher than 99% after reacting for 600 h. The selectivity of caprolactam is higher, up to more than 96%. The selectivity of ethyl-ε-caprolactim condensate in by-products is lower, and the total selectivity (the sum of the selectivity of caprolactam and the selectivity of ethyl-ε-caprolactim condensate) can reach more than 97%, and the effect is remarkable.

[0092] Example 16

[0093] (1) 0.06 g of TiCl4 was added to 100 g of tetraethyl orthosilicate. After complete dissolution, 120 g of 25 wt% tetrapropylammonium hydroxide and 150 g of water were added and mixed, and stirred at room temperature for 8 h to form a homogeneous colloidal mixture;

[0094] (2) Ethanol was removed at 85 °C (water was continuously replenished during the process to keep the material at a certain liquid level), and the time was 20 h. Finally, 2.7 g of ammonium fluoride was added to obtain a crystallization mother liquor. The molar ratio of the mixture was SiO2∶NH4F∶TPAOH∶H2O = 1∶0.15∶0.3∶17, and the mass ratio of SiO2 to Ti 4+ was 1902∶1;

[0095] (3) The above mixture was transferred into a 2 L reaction kettle with a polytetrafluoroethylene lining, hydrothermally crystallized at 120 °C for 60 h, washed, filtered, dried at 120 °C for 24 h, and finally calcined at 550 °C for 6 h to obtain molecular sieve A7.

[0096] The specific physical and chemical properties of the A7 sample are listed in Table 4

[0097] Comparative Example 5

[0098] This comparative example illustrates the molecular sieve prepared without adding a fluorine-containing compound.

[0099] Same as Example 16, the difference from Example 16 is only that no fluorine-containing compound is added.

[0100] The specific physical and chemical properties of Sample D3 are listed in Table 4

[0101] Example 17

[0102] (1) 0.06 g of GeCl4 was added to 100 g of tetraethyl orthosilicate. After complete dissolution, 120 g of 25 wt% tetrapropylammonium hydroxide and 150 g of water were added and mixed, and stirred at room temperature for 8 h to form a homogeneous colloidal mixture;

[0103] (2) Ethanol was removed at 85 °C (water was continuously added during the process to maintain the material at a certain liquid level), for 20 h, and finally 2.7 g of ammonium fluoride was added to obtain a crystallization mother liquor. The molar ratio of the mixture was SiO2∶NH4F∶TPAOH∶H2O = 1∶0.15∶0.3∶17, and the mass ratio of SiO2 to Ge 4+ was 1419∶1;

[0104] (3) The above mixture was transferred into a 2 L autoclave with a polytetrafluoroethylene lining, hydrothermally crystallized at 120 °C for 60 h, washed, filtered, dried at 120 °C for 24 h, and finally calcined at 550 °C for 6 h to obtain molecular sieve A8.

[0105] The specific physical and chemical properties of Sample A8 are listed in Table 4

[0106] Comparative Example 6

[0107] This comparative example illustrates the molecular sieve prepared without adding a fluorine-containing compound.

[0108] Same as Example 17, the difference from Example 17 is only that no fluorine-containing compound is added.

[0109] The specific physical and chemical properties of Sample D4 are listed in Table 4

[0110] Example 18

[0111] (1) 0.06 g of Ga(NO3)3 was added to 100 g of tetraethyl orthosilicate. After complete dissolution, 120 g of 25 wt% tetrapropylammonium hydroxide and 150 g of water were added and mixed, and stirred at room temperature for 8 h to form a homogeneous colloidal mixture;

[0112] (2) Ethanol was removed at 85 °C (water was continuously added during the process to maintain the material at a certain liquid level), for 20 h, and finally 2.7 g of ammonium fluoride was added to obtain a crystallization mother liquor. The molar ratio of the mixture was SiO2∶NH4F∶TPAOH∶H2O = 1∶0.15∶0.3∶17, and the mass ratio of SiO2 to Ga 3+ was 907∶1;

[0113] (3) Transfer the above mixture into a 2 L autoclave with a polytetrafluoroethylene liner, hydrothermally crystallize at 120 °C for 60 h, wash, filter, dry at 120 °C for 24 h, and finally calcine at 550 °C for 6 h to obtain molecular sieve A9.

[0114] The specific physical and chemical properties of the A9 sample are listed in Table 4.

[0115] Comparative Example 7

[0116] This comparative example illustrates the molecular sieve prepared without adding a fluorine-containing compound.

[0117] Same as Example 18, the difference from Example 18 is only that: no fluorine-containing compound is added.

[0118] The specific physical and chemical properties of the D5 sample are listed in Table 4.

[0119] Example 19

[0120] (1) Add 0.06 g of La(NO3)3·6H2O to 100 g of tetraethyl orthosilicate. After complete dissolution, add 120 g of 25 wt% tetrapropylammonium hydroxide and 150 g of water and mix. Stir at room temperature for 8 h to form a homogeneous colloidal mixture;

[0121] (2) Carry out alcohol evaporation at a temperature of 85 °C (constantly replenish water during the process to maintain the material at a certain liquid level), for a time of 20 h, and finally add 2.7 g of ammonium fluoride to obtain a crystallization mother liquor. The molar ratio of the mixture is SiO2∶NH4F∶TPAOH∶H2O = 1∶0.15∶0.3∶17, and the mass ratio of SiO2 to La 3+ is 1496∶1;

[0122] (3) Transfer the above mixture into a 2 L autoclave with a polytetrafluoroethylene liner, hydrothermally crystallize at 120 °C for 60 h, wash, filter, dry at 120 °C for 24 h, and finally calcine at 550 °C for 6 h to obtain molecular sieve A10.

[0123] The specific physical and chemical properties of the A10 sample are listed in Table 4.

[0124] Comparative Example 8

[0125] This comparative example illustrates the molecular sieve prepared without adding a fluorine-containing compound.

[0126] Same as Example 19, the difference from Example 19 is only that: no fluorine-containing compound is added. The specific physical and chemical properties of the D6 sample are listed in Table 4.

[0127] Table 4

[0128]

[0129] Examples 20 - 23

[0130] The stability evaluation was carried out for 600 hours under the reaction conditions of Example 7.

[0131] The molecular sieve samples were changed to A7, A8, A9, and A10 respectively. The evaluation results are shown in Table 5.

[0132] Comparative Examples 9 - 12

[0133] The stability evaluation was carried out for 600 hours under the reaction conditions of Example 7.

[0134] The comparative molecular sieve samples were changed to D3, D4, D5, and D6 respectively. The evaluation results are shown in Table 5.

[0135] Table 5

[0136]

Claims

1. A gas-phase Beckmann rearrangement method, which comprises contacting cyclohexanone oxime with Silicate-1 molecular sieve in the presence of nitrogen and a solvent under rearrangement reaction conditions, is characterized in that, The Silicate-1 molecular sieve contains metal, A HB : A ISO is (15 - 50):1, A HB and A ISO respectively represent the peak intensities at the wavenumbers of 3400 cm -1 and at the wavenumber of 3725 cm -1 in the infrared hydroxyl spectrum of the Silicate-1 molecular sieve, expressed by the peak area; The preparation method of the Silicate-1 molecular sieve includes mixing a silicon source, a metal source, a fluorine-containing compound, an organic template agent and water to obtain a colloidal mixture; hydrothermally crystallizing the colloidal mixture to obtain a crystallized product; The crystallized product is washed, filtered, dried, and calcined; in the preparation method, the molar ratio of the silicon source: the fluorine-containing compound: the organic template agent: water is 1:(0.01 - 0.50):(0.05 - 0.50):(5 - 100); the weight ratio of the silicon source: the metal source is (100 - 100000):1; the silicon source is calculated as SiO2, and the metal source is calculated as the metal element.

2. The method according to claim 1, wherein, The molar ratio of the nitrogen gas to the cyclohexanone oxime is (10 - 80):

1.

3. The method according to claim 2, wherein, The molar ratio of the nitrogen gas to the cyclohexanone oxime is (30 - 60):

1.

4. The method according to claim 1, wherein, The solvent is selected from at least one of the aliphatic alcohols having 1 to 6 carbon atoms.

5. The method according to claim 1, wherein The solvent is methanol and / or ethanol.

6. The method according to claim 1, wherein The molar ratio of the solvent to the cyclohexanone oxime is (2 - 10):

1.

7. The method according to claim 1, wherein The molar ratio of the solvent to the cyclohexanone oxime is (3 - 8):

1.

8. The method according to claim 1, wherein The rearrangement reaction conditions include: the weight hourly space velocity of cyclohexanone oxime is 0.1 - 16 h -1 , the reaction temperature is 300 - 500 °C, and the reaction pressure is 0.1 - 0.5 MPa.

9. The method according to claim 1, further comprising a step of first mixing cyclohexanone oxime and water in a molar ratio of 1:(0.01 - 2.5).

10. The method according to claim 1, wherein, The metal is selected from at least one metal element among transition metal elements, Group IIIA elements, and Group IVA elements.

11. The method according to claim 10, wherein, The metal is selected from at least one of Group IVB elements and Group VB elements.

12. The method according to claim 10, wherein, The metal is at least one of the elements Ti, Nb, Ta, Ga, La, Ge, Sn, and Pb.

13. The method according to any one of claims 1, 10 - 12, wherein The metal, based on the dry weight of the Silicate-1 molecular sieve, has a content of 10 - 5000 ppm.

14. The method according to claim 1, wherein The metal has a content of 15 - 4000 ppm.

15. The method according to claim 14, wherein, The metal has a content of 50 - 800 ppm.

16. The method according to claim 15, wherein, The metal has a content of 200 - 500 ppm.

17. The method according to claim 1, wherein The said A HB : A ISO is (15 - 25):

1.

18. The method according to claim 1, wherein The Silicate-1 molecular sieve has a BET specific surface area of 300 - 500 m 2 / g, an external specific surface area of 20 - 100 m 2 / g, a particle size of 0.01 - 1 μm, and a relative crystallinity of 70% - 110%.

19. The method according to claim 18, wherein, The BET specific surface area is 350 - 500 m 2 / g, the external specific surface area is 50 - 85 m 2 / g, and the particle size is 0.1 - 0.3 μm.

20. The method according to claim 18, wherein The BET specific surface area is 440 - 480 m 2 / g, the external specific surface area is 20 - 80 m 2 / g, the particle size is 0.15 - 0.3 μm, and the relative crystallinity is 80% - 90%.

21. The method according to claim 18, wherein, The external specific surface area is 50 - 85 m 2 / g.

22. The method according to claim 18, wherein, The external specific surface area is 55 - 75 m 2 / g.

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