A process for the preparation of adiponitrile

Abstract

The present disclosure relates to a method for preparing adiponitrile, comprising the following steps: contacting cyclohexanone oxime, an ammonia source and a catalyst to perform a catalytic reaction; the catalyst comprises a hierarchical pore Silicalite-1 molecular sieve, and the hierarchical pore Silicalite-1 molecular sieve has a plurality of cavity structures in the crystal. The present disclosure does not need to use toxic and harmful solvents, and has higher cyclohexanone oxime conversion rate and adiponitrile selectivity.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of organic chemical industry, in particular to a method for preparing adiponitrile. BACKGROUND

[0002] Adiponitrile (ADN) is also known as 1,4-dicyanobutane, with the molecular formula of NC(CH3)4CN. It is a colorless transparent oily liquid, slightly bitter, hardly soluble in water, soluble in methanol, ethanol, chloroform, flammable in the presence of fire or high heat. Adiponitrile can be added with hydrogen to generate hexamethylene diamine, which can react with adipic acid under strict material ratio to generate nylon 66 salt. Adiponitrile is an important intermediate for synthesizing nylon 66, which is the most important and valuable industrial use of adiponitrile. Research has found that hexamethylene diamine can be used to synthesize 1,6-hexamethylene diisocyanate (HDI), which is another important use of the downstream product chain of adiponitrile. Adiponitrile can also be used to prepare rubber additives, pesticides and fungicides, rocket fuel and high polymer materials, and can also be used as plasticizers, additives, colorants, textile auxiliaries and extractants for aromatic extraction.

[0003] The traditional production process of adiponitrile mainly includes the following three kinds: adipic acid ammoniation method, propylene cyanide electrolytic dimerization method and butadiene cyanation method; in addition, there is a caprolactam degradation and hydrolysis method, but this method has not been reported on a large scale. The adipic acid ammoniation method is divided into gas phase method and liquid phase method; the liquid phase method is divided into batch method and continuous method, the process flow is long, the product quality is poor, the impurities are more and the yield is low; the propylene cyanide electrolytic dimerization method can be divided into two kinds of membrane-free electrolysis method and membrane electrolysis method, the process has small pollution, short flow and small investment, but due to the high toxicity and strong corrosion of propylene cyanide, and the high price of propylene cyanide and large electrolytic energy consumption, it is difficult to mass-produce and has small profit space; the butadiene cyanation method is divided into chlorination cyanation method and direct cyanation method, the direct cyanation method of butadiene has short process route, small investment and low raw material cost, and small pollution, but this method needs to use hydrocyanic acid, which is toxic and not conducive to popularization and use. SUMMARY

[0004] The purpose of the present disclosure is to provide a method for preparing adiponitrile without using toxic and harmful solvents, and with high cyclohexanone oxime conversion rate and adiponitrile selectivity.

[0005] In order to achieve the above purpose, the present disclosure provides a method for preparing adiponitrile, comprising the following steps:

[0006] contacting cyclohexanone oxime, an ammonia source and a catalyst for catalytic reaction;

[0007] The catalyst comprises a hierarchical pore Silicalite-1 molecular sieve, which has a plurality of cavity structures in the crystal.

[0008] Optionally, the method further comprises:

[0009] contacting cyclohexanone oxime, an ammonia source and a catalyst in the presence of a solvent to perform an intramolecular rearrangement and ring-opening cyanation reaction;

[0010] Optionally, the solvent is selected from one or more of methanol, ethanol, propanol, butanol and cyclohexanol; and the ammonia source is selected from aqueous ammonia or ammonia gas; preferably, the ammonia source is selected from aqueous ammonia with a concentration of 25-30 wt.%.

[0011] Preferably, the molar ratio of cyclohexanone oxime to solvent is 1:(3-50), preferably 1:(5-30); and the weight ratio of ammonia source (calculated as pure ammonia) to solvent is 1:(10-5000), preferably 1:(50-4000).

[0012] Optionally, the conditions of the catalytic reaction include: a reaction temperature of 200-450°C, preferably 350-400°C; a reaction time of 1-72h, preferably 10-24h; a reaction pressure of 0.1-3MPa, preferably 0.1-2MPa; and a weight hourly space velocity (WHSV) of cyclohexanone oxime of 0.1-15h -1 , preferably 0.3-13h -1 .

[0013] Optionally, the reactor for the catalytic reaction is selected from any one of a fixed bed reactor, a tank reactor, a moving bed reactor, a suspended bed reactor or a slurry bed reactor.

[0014] Optionally, the size of the single cavity structure in the hierarchical-pore Silicalite-1 molecular sieve is 5-150nm, preferably 10-100nm.

[0015] Preferably, the volume of all the cavity structures accounts for 10-95 vol.% of the total volume of the molecular sieve, further preferably 15-90 vol.%.

[0016] Optionally, the shape of the cavity structure is selected from one or more of a sphere, a cube, an ellipsoid and an irregular cube.

[0017] Optionally, the hierarchical-pore Silicalite-1 molecular sieve has the following 31 P MAS NMR characteristics:

[0018] the peak intensity of the characteristic peak of the multi-level pore Silicalite-1 molecular sieve at a chemical shift of -5±1 ppm is denoted as N1; the peak intensity of the characteristic peak of the multi-level pore Silicalite-1 molecular sieve at a chemical shift of -34±1 ppm is denoted as N2; the peak intensity of the characteristic peak of the multi-level pore Silicalite-1 molecular sieve at a chemical shift of -61±1 ppm is denoted as N3;

[0019] X1 as defined in the following formula (1) is any value between 0.10 and 0.30;

[0020] X1 = N1 / N3 formula (1); and

[0021] X2 as defined in the following formula (2) is any value between 0.15 and 0.45;

[0022] X2 = N2 / N3 formula (2);

[0023] Preferably, the X1 is any value between 0.15 and 0.25; the X2 is any value between 0.20 and 0.35.

[0024] Optionally, the multi-level pore Silicalite-1 molecular sieve has the following 29 Si MAS NMR characteristics:

[0025] the peak area of the spectrum peak of the multi-level pore Silicalite-1 molecular sieve at a chemical shift in the range of -102 to -104 ppm is denoted as Q 3 the peak area of the spectrum peak of the multi-level pore Silicalite-1 molecular sieve at a chemical shift in the range of -112 to -114 ppm is denoted as Q 4 X3 as defined in the following formula (3) is any value between 2 and 30%:

[0026] X3 = Q 3 / Q 4 x 100% formula (3);

[0027] Preferably, X3 is any value between 5 and 25%.

[0028] Optionally, the multi-level pore Silicalite-1 molecular sieve has the following 1 H MAS NMR characteristics:

[0029] the peak area of the spectrum peak of the multi-level pore Silicalite-1 molecular sieve at a chemical shift in the range of -102 to -104 ppm is denoted as Q 1In the peak separation result of the spectrum peak in the chemical shift range of 1-6 ppm of the H MAS NMR spectrum: the peak area of the spectrum peak in the chemical shift range of 1.6-1.8 ppm is recorded as A1, the peak area of the spectrum peak in the chemical shift range of 2.0-2.2 ppm is recorded as A2, the peak area of the spectrum peak in the chemical shift range of 3.1-3.3 ppm is recorded as A3, the peak area of the spectrum peak in the chemical shift range of 4.4-4.6 ppm is recorded as A4, and the sum of the peak areas of A1-A4 is recorded as A0;

[0030] X as defined in the following formula (4-1) 4-1 is any value between 14-32%:

[0031] X 4-1 =A1 / A0x100% formula (4-1);

[0032] X as defined in the following formula (4-2) 4-2 is any value between 23-41%:

[0033] X 4-2 =A2 / A0x100% formula (4-2);

[0034] X as defined in the following formula (4-3) 4-3 is any value between 16-35%:

[0035] X 4-3 =A3 / A0x100% formula (4-3);

[0036] X as defined in the following formula (4-4) 4-4 is any value between 4-20%:

[0037] X 4-4 =A4 / A0x100% formula (4-4).

[0038] Optionally, the hierarchical pore Silicalite-1 molecular sieve comprises a molecular sieve particle composed of a single crystal grain, and / or a molecular sieve particle composed of a plurality of crystal grains aggregated together;

[0039] Optionally, the average particle size of the molecular sieve particle is 0.1-2 μm, preferably 0.2-1.2 μm; the BET specific surface area is 300-650 m 2 / g, preferably 350-550 m 2 / g; the micropore specific surface area is 200-550 m 2 / g, preferably 250-450 m 2 / g; the total pore volume is 0.2-0.7 cm 3 / g, preferably 0.3-0.5 cm 3 / g; the mesopore volume is 0.1-0.5 cm 3 / g, preferably 0.2-0.4 cm 3 / g;

[0040] Optionally, the multi-level pore Silicalite-1 molecular sieve has a hysteresis loop between the adsorption isotherm and the desorption isotherm of low-temperature nitrogen adsorption.

[0041] Optionally, the multi-level pore Silicalite-1 molecular sieve is prepared by a preparation method comprising the following steps:

[0042] S1, mixing a silicon source, a first template agent, water, a silylation reagent and a structure filler to obtain a reaction mixture, wherein the structure filler is an amphiphilic surfactant and / or a hard template agent;

[0043] S2, sequentially performing a first hydrothermal crystallization treatment and a first calcination treatment on the reaction mixture to obtain a molecular sieve intermediate;

[0044] S3, mixing the molecular sieve intermediate, a second template agent and water, and then sequentially performing a second hydrothermal crystallization treatment and a second calcination treatment.

[0045] Optionally, in step S1, the molar ratio of the silicon source: the first template agent: water: the silylation reagent is (1):(0.01-2):(1-50):(0.02-0.2); preferably (1):(0.02-0.3):(5-30):(0.03-0.15); and the weight ratio of SiO2 to the structure filler in the reaction mixture is (5-40):1, preferably (5-30):1.

[0046] Optionally, in step S1, the silicon source is selected from at least one of organosilicone grease, solid silica gel, white carbon black and silica sol; preferably selected from at least one of organosilicone grease, solid silica gel and white carbon black;

[0047] Further preferably, the organosilicone grease has a general structure as shown in the following formula (A):

[0048]

[0049] wherein R a , R b , R c , R d are each independently selected from an alkyl group having 1-6 carbon atoms, the alkyl group being a branched or straight-chain alkyl group; preferably, R a , R b , R c , R deach independently selected from a linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 4 carbon atoms; further preferably, the R a , R b , R c , R d each independently selected from a methyl group, an ethyl group, a n-propyl group, an i-propyl group, a n-butyl group, a sec-butyl group, an i-butyl group, or a t-butyl group; further preferably, the organosilicon grease is selected from one or more of tetramethyl silicate, tetraethyl silicate, tetrabutyl silicate, and dimethyldiethyl silicate.

[0050] Optionally, the first template agent in step S1 and the second template agent in step S3 are an organic base; and each independently is preferably at least one selected from a quaternary ammonium base, an aliphatic amine, and an aliphatic alcohol amine;

[0051] Further preferably, the first template agent and the second template agent are each independently at least one selected from quaternary ammonium bases having a structure shown in the following formula (B):

[0052] R1, R2, R3, and R4are each independently selected from an alkyl group having 1 to 4 carbon atoms, preferably a linear alkyl group having 1 to 4 carbon atoms and a branched alkyl group having 3 to 4 carbon atoms, further preferably R1, R2, R3, and R4are each independently selected from a methyl group, an ethyl group, a n-propyl group, an i-propyl group, a n-butyl group, a sec-butyl group, an i-butyl group, or a t-butyl group;

[0053] Further preferably, the first template agent and the second template agent are each independently tetrapropylammonium hydroxide or a mixture of tetrapropylammonium hydroxide and one or more selected from tetrapropylammonium chloride and tetrapropylammonium bromide.

[0054] Optionally, in step S1, the silanizing agent has a general formula of R5Si(R6)(R7)R8, where R5, R6, R7, and R8are each independently a halogen, an alkyl group, an alkoxy group, an aromatic group, a thiol group, or an amine group, and at least one of R5, R6, R7, and R8is an alkyl group, an alkoxy group, an aromatic group, a thiol group, or an amine group; the number of carbon atoms of the alkyl group, the alkoxy group, the thiol group, and the amine group is independently C1-C 18 ;

[0055] Preferably, the silanization agent is selected from one or more of dimethyldichlorosilane, N-phenyl-3-aminopropyltrimethoxysilane, phenyltrimethoxysilane, 1,7-dichlorooctylmethyltetrasiloxane, hexadecyltrimethoxysilane, octyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane; further preferably, the silanization agent is selected from one or more of N-phenyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

[0056] Optionally, in step S1, the structure filler is selected from one or more of cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, PEO-PPO-PEO triblock copolymer, mesoporous carbon, and natural cellulose.

[0057] Optionally, step S1 comprises:

[0058] a. mixing a silicon source, a first template agent, and water to obtain a hydrolytic sol of silicon;

[0059] b. adding a silanization agent and a structure filler to the hydrolytic sol of silicon respectively, and mixing to obtain the reaction mixture;

[0060] Optionally, the mixing in step a is performed under the conditions of stirring at 40-90°C for 6-12h.

[0061] Optionally, the mixing in step b is performed under the conditions of stirring at 20-50°C for 2-4h.

[0062] Preferably, the silicon source is an organosilicon grease, and after mixing the silicon source, the first template agent, and water in step a, a hydrolytic alcohol-removing treatment is further performed to obtain the hydrolytic sol of silicon.

[0063] Optionally, the hydrolytic alcohol-removing treatment is performed under the conditions of stirring hydrolysis at 40-90°C for 6-12h; preferably, stirring hydrolysis at 60-85°C for 8-10h.

[0064] Optionally, in step S3, the weight ratio of the molecular sieve intermediate: the second template agent: water is 1:(0.01-1.5):(1-15); preferably, 1:(0.1-1):(2-10).

[0065] Optionally, the first hydrothermal crystallization treatment in step S2 and the second hydrothermal crystallization treatment in step S3 are each independently performed under the conditions of hydrothermal crystallization time of 0.25-7 days, hydrothermal crystallization temperature of 130-200°C; preferably, hydrothermal crystallization time of 1-3 days, hydrothermal crystallization temperature of 150-180°C; and pressure of autogenous pressure.

[0066] The conditions of the first calcination treatment in step S2 and the second calcination treatment in step S3 each independently include a calcination temperature of 300-700°C and a calcination time of 1-16h; preferably, the calcination temperature is 400-600°C and the calcination time is 2-5h.

[0067] By the above technical solution, the present disclosure provides a method for preparing adiponitrile, which realizes intramolecular rearrangement and ring-opening cyanation reaction of cyclohexanone oxime under non-homogeneous non-toxic and harmless reaction conditions to obtain adiponitrile. The method can obtain high conversion rate of cyclohexanone oxime and selectivity of adiponitrile under mild reaction conditions, and has high industrial application value. The catalyst used in the catalytic reaction is a molecular sieve material, which has thermal stability and chemical stability, and has a multi-level pore structure, which is beneficial to the diffusion of the product. In addition, the molecular sieve has a multi-cavity structure in the crystal, and the cavity structure has a large number of silicon hydroxyl active centers. The multi-cavity structure provides a large number of independent reaction units, and the concentrated distribution of the hydroxyl groups makes the molecular sieve have both acid and Lewis acid properties, and has a large specific surface area and pore volume, which is beneficial to efficient catalytic reaction.

[0068] Other features and advantages of the present disclosure will be described in detail in the following specific embodiment part. BRIEF DESCRIPTION OF DRAWINGS

[0069] The accompanying drawings are included to provide a further understanding of the present disclosure, and constitute a part of the specification, and are used together with the following specific embodiments to explain the present disclosure, but do not constitute a limitation on the present disclosure. In the drawings:

[0070] Figure 1 is a TEM electron microscope picture of the molecular sieve product obtained in Preparation Example 1;

[0071] Figure 2 is an XRD spectrum of the molecular sieve product obtained in Preparation Example 1;

[0072] Figure 3 is a P-TMP MAS NMR spectrum of the molecular sieve product obtained in Preparation Example 1 and the molecular sieve product obtained in Preparation Comparative Example 2; 31

[0073] Figure 4 is a SEM electron microscope picture of the molecular sieve product obtained in Preparation Example 1;

[0074] Figure 5 is a BET curve of the molecular sieve product obtained in Preparation Example 1;

[0075] Figure 6 is an infrared hydroxyl spectrum of the molecular sieve product obtained in Preparation Example 1;​​

[0076] Figure 7 TEM images of the intermediate product obtained in Preparation Example 1 are shown in 29 Si MAS NMR spectrum;

[0077] Figure 8 TEM images of the intermediate product obtained in Preparation Example 1 are shown in 1 H MAS NMR spectrum;

[0078] Figure 9 TEM images of the intermediate product obtained in Preparation Example 1 are shown in

[0079] Figure 10 XRD spectrum of the molecular sieve product obtained in Preparation Example 10 is shown in

[0080] Figure 11 XRD spectrum of the molecular sieve product obtained in Preparation Example 11 is shown in

[0081] Figure 12 TEM images of the molecular sieve product obtained in Preparation Example 1 are shown in DETAILED DESCRIPTION

[0082] The detailed description of the specific embodiments of the present disclosure is described below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0083] The present disclosure provides a method for preparing adiponitrile, comprising the following steps:

[0084] contacting cyclohexanone oxime, an ammonia source and a catalyst for catalytic reaction;

[0085] The catalyst comprises a hierarchical pore Silicalite-1 molecular sieve, which has a plurality of cavity structures in the crystal.

[0086] The present disclosure provides a method for preparing adiponitrile, which realizes intramolecular rearrangement and ring-opening cyanation reaction of cyclohexanone oxime under non-homogeneous non-toxic and harmless reaction conditions to obtain adiponitrile. The method can obtain high conversion rate of cyclohexanone oxime and selectivity of adiponitrile under mild reaction conditions, and has high industrial application value. The catalyst used in the catalytic reaction is a molecular sieve material, which has thermal stability and chemical stability, and has a hierarchical pore structure, which is beneficial to the diffusion of the product. In addition, the molecular sieve has a plurality of cavity structures in the crystal, and the cavity structure has a large number of silicon hydroxyl active centers. The multi-cavity structure provides a large number of independent reaction units, and the concentrated distribution of the nest hydroxyl groups makes the molecular sieve have both acid and Lewis acid properties, and has a large specific surface area and pore volume, which is beneficial to efficient catalytic reaction. acid and Lewis acid properties, and has a large specific surface area and pore volume, which is beneficial to efficient catalytic reaction.

[0087] In one embodiment, the method further comprises: contacting cyclohexanone oxime, an ammonia source and a catalyst in the presence of a solvent to perform an intramolecular rearrangement ring-opening cyano reaction.

[0088] Optionally, the solvent is selected from one or more of methanol, ethanol, propanol, butanol and cyclohexanol; and the ammonia source is selected from aqueous ammonia or ammonia gas; preferably, the ammonia source is selected from aqueous ammonia with a concentration of 25-30 wt%.

[0089] In one preferred embodiment, the molar ratio of cyclohexanone oxime to solvent is 1:(3-100), preferably 1:(10-50); and the weight ratio of ammonia source (calculated as pure ammonia) to solvent is 1:(1000-10000), preferably 1:(1000-2000).

[0090] In one embodiment, the conditions of the catalytic reaction include: a reaction temperature of 200-450°C; a reaction time of 1-72h; a reaction pressure of 0.1-3MPa; and a weight hourly space velocity (WHSV) of the cyclohexanone oxime of 0.1-15h -1 .

[0091] In one preferred embodiment, the conditions of the catalytic reaction include: a reaction temperature of 350-400°C; a reaction time of 10-24h; a reaction pressure of 0.1-2MPa; and a weight hourly space velocity (WHSV) of the cyclohexanone oxime of 0.3-13h -1 . According to this embodiment, higher conversion of cyclohexanone oxime and selectivity of adiponitrile can be achieved.

[0092] In one specific embodiment, the reactor for the catalytic reaction is selected from any one of a fixed bed reactor, a tank reactor, a moving bed reactor, a suspended bed reactor or a slurry bed reactor.

[0093] In one preferred embodiment, the hierarchical porous Silicalite-1 molecular sieve has a plurality of cavity structures within the crystal; wherein the size of a single cavity structure is 5-150nm, preferably 10-100nm.

[0094] In the present disclosure, the cavity structure and its size in the molecular sieve are obtained by transmission electron microscopy. In the present disclosure, the size of the cavity structure refers to the distance between any two positions on the cavity wall of the cavity structure that pass through the center of the cavity structure in the transmission electron microscopy photograph of the molecular sieve; for example, “the size of a single cavity structure is 5-150nm” means that the distance between any two positions on the cavity wall of any one cavity structure in the molecular sieve that pass through the center of the cavity structure is within the range of 5-150nm.

[0095] In a preferred embodiment, the volume of all the cavity structures accounts for 10-95% of the total volume of the molecular sieve, more preferably 15-90% by volume;

[0096] Optionally, the shape of the cavity structure is selected from one or more of the following: sphere, cube, ellipsoid, and irregular cube.

[0097] In one embodiment, the hierarchical porous Silicalite-1 molecular sieve has the following characteristics: 31 P MAS NMR characteristics:

[0098] The peak intensity of the characteristic peak at a chemical shift of -5±1ppm for the hierarchical porous Silicalite-1 molecular sieve is denoted as N1; the peak intensity of the characteristic peak at a chemical shift of -34±1ppm for the hierarchical porous Silicalite-1 molecular sieve is denoted as N2; and the peak intensity of the characteristic peak at a chemical shift of -61±1ppm for the hierarchical porous Silicalite-1 molecular sieve is denoted as N3.

[0099] As defined in equation (1), X1 can be any value between 0.10 and 0.30;

[0100] X1 = N1 / N3 (1); and

[0101] As defined in equation (2), X2 is any value between 0.15 and 0.45;

[0102] X2 = N2 / N3 (Equation 2).

[0103] In this disclosure, for hierarchical porous Silicalite-1 molecular sieves 31 In the P-TMP MAS NMR spectrum analysis, trimethylphosphorus (TMP) was used as the probe molecule, and the testing method is a conventional method in the art. The inventors of this disclosure have discovered that when the hierarchical porous Silicalite-1 molecular sieve simultaneously possesses… When considering acid and Lewis acid properties, trimethylphosphorus (TMP) is used as a probe molecule. 31 In the pMAS NMR spectrum, a chemical shift of -5 ± 1 ppm was used as... The characteristic peaks of acid properties were determined, with a chemical shift of -34±1 ppm as the characteristic peak of Lewis acid properties, and a chemical shift of -61±1 ppm as the characteristic peak of TMP physisorption; using these TMP physisorption characteristic peaks as a comparison benchmark, ... The peak intensities of the characteristic peaks of the acid properties and the Lewis acid properties are compared with the peak intensity of the characteristic peak of the physical adsorption of the TMP, and when the ratio of the peak intensities of the characteristic peaks of the two acid properties to the peak intensity of the characteristic peak of the physical adsorption of the TMP meets a certain range, the hierarchical pore Silicalite-1molecular sieve can have better catalytic activity and reaction stability; in the catalytic reaction of preparing adiponitrile from cyclohexanone oxime, it has high cyclohexanone oxime conversion rate and adiponitrile selectivity.

[0104] In a preferred embodiment, X1 is any value between 0.15 and 0.25; X2 is any value between 0.2 and 0.35. When the X1 and X2 of the hierarchical pore Silicalite-1molecular sieve meet the range of the present embodiment, the hierarchical pore Silicalite-1molecular sieve has higher catalytic activity and catalytic stability.

[0105] In an embodiment, the hierarchical pore Silicalite-1molecular sieve has the following 29 Si MAS NMR characteristics:

[0106] The peak area of the spectrum peak in the range of -102 to -104 ppm of the chemical shift of the hierarchical pore Silicalite-1molecular sieve is recorded as Q 3 The peak area of the spectrum peak in the range of -112 to -114 ppm of the chemical shift is recorded as Q 4 X3 defined as formula (3) below is any value between 2 and 30%:

[0107] X3 = Q 3 / Q 4 × 100% formula (3);

[0108] Preferably, X3 is any value between 5 and 25%.

[0109] In the present disclosure, the spectrum peak with a chemical shift near -103 ppm represents a three-coordinated silicon group, and the spectrum peak with a chemical shift near -113 ppm represents a four-coordinated silicon group, and the hierarchical pore Silicalite-1molecular sieve has abundant silicon hydroxyl groups.

[0110] The hierarchical pore Silicalite-1molecular sieve provided by the present disclosure has the following characteristics: 1In the H MAS NMR spectrum, the peak signal in the chemical shift range of 1.6-1.8 ppm represents isolated silicon hydroxyl, and the peak signal in the chemical shift range of 2-6 ppm (2.0-2.2 ppm, 3.1-3.3 ppm and 4.4-4.6 ppm, respectively) represents hydrogen-bonded silicon hydroxyl. The relationship between the peak area of the above four silicon hydroxyl peaks and the total peak area can be used to reflect the catalytic activity and catalytic stability of the hierarchical Silicalite-1 molecular sieve.

[0111] In one embodiment, the hierarchical Silicalite-1 molecular sieve has the following 1 H MAS NMR characteristics:

[0112] In the hierarchical Silicalite-1 molecular sieve 1 In the peak separation result of the spectrum peak in the chemical shift range of 1-6 ppm in the H MAS NMR spectrum: the peak area of the spectrum peak in the chemical shift range of 1.6-1.8 ppm is denoted as A1, the peak area of the spectrum peak in the chemical shift range of 2.0-2.2 ppm is denoted as A2, the peak area of the spectrum peak in the chemical shift range of 3.1-3.3 ppm is denoted as A3, the peak area of the spectrum peak in the chemical shift range of 4.4-4.6 ppm is denoted as A4, and the sum of the peak areas of A1-A4 is denoted as A0.

[0113] X as defined in the following formula (4-1) 4-1 is any value between 14 and 32%:

[0114] X 4-1 =A1 / A0x100% formula (4-1);

[0115] X as defined in the following formula (4-2) 4-2 is any value between 23 and 41%:

[0116] X 4-2 =A2 / A0x100% formula (4-2);

[0117] X as defined in the following formula (4-3) 4-3 is any value between 16 and 35%:

[0118] X 4-3 =A3 / A0x100% formula (4-3);

[0119] X as defined in the following formula (4-4) 4-4 is any value between 4 and 20%:

[0120] X 4-4 =A4 / A0x100% formula (4-4).

[0121] In a preferred embodiment, the X of the hierarchical porous Silicalite-1 molecular sieve 4-1 X is any value between 17% and 30%. 4-2 X is any value between 27% and 38%. 4-3 X is any value between 19% and 32%. 4-4 Any value between 6% and 18%. When the hierarchical porous Silicalite-1 molecular sieve meets the X requirement of this embodiment... 1-1 ~X 1-4 Numerical values ​​indicate that it exhibits high cyclohexanone oxime conversion and adiponitrile selectivity in the catalytic reaction of cyclohexanone oxime to adiponitrile.

[0122] In one specific embodiment, the hierarchical porous Silicalite-1 molecular sieve comprises molecular sieve particles consisting of single crystals, and / or molecular sieve particles composed of aggregates of multiple crystals; optionally, the average particle size of the molecular sieve particles is 0.1–2 μm, preferably 0.2–1.2 μm; and the external specific surface area is 300–800 cm². 2 / g, preferably 400-600cm 2 / g; total pore volume is 0.2–0.7 cm³. 3 / g, preferably 0.3~0.5cm 3 / g; mesopore volume is 0.1~0.5cm³ 3 / g, preferably 0.2~0.4cm 3 / g.

[0123] In a preferred embodiment, a hysteresis loop exists between the adsorption isotherm and desorption isotherm of the hierarchical porous Silicalite-1 molecular sieve for low-temperature nitrogen adsorption.

[0124] In one specific embodiment, the initial relative pressure (P / P0) at which the hysteresis loop appears is 0.2 to 0.99, preferably 0.4 to 0.99.

[0125] In one specific embodiment, the configuration of the hierarchical porous Silicalite-1 molecular sieve is selected from one or more of the MFI topology, MEL topology, BEA topology and SVR topology.

[0126] In a preferred embodiment, the hierarchical porous Silicalite-1 molecular sieve is prepared by a method comprising the following steps:

[0127] S1. Mix the silicon source, the first template agent, water, the silanizing agent and the structural filler to obtain a reaction mixture, wherein the structural filler is an amphiphilic surfactant and / or a hard template agent;

[0128] S2, sequentially performing a first hydrothermal crystallization treatment and a first calcination treatment on the reaction mixture to obtain a molecular sieve intermediate;

[0129] S3, mixing the molecular sieve intermediate, a second template agent and water, and then sequentially performing a second hydrothermal crystallization treatment and a second calcination treatment.

[0130] The present disclosure can produce the effect of expanding the molecular sieve layer by introducing a silanization agent and a structural filler of a macromolecule into a molecular sieve synthesis raw material, prepare a molecular sieve material with open pores, and then add a second template agent to perform dissolution-recrystallization, thereby preparing a hierarchical pore Silicalite-1 molecular sieve with a multi-cavity structure.

[0131] Specifically, in the present disclosure, the silanol groups of the silanization agent and the silanol groups of the organosilicon source hydrolyze and condense to form stable Si-O-Si bonds, thereby ensuring the realization of the effect of expanding the layer. In addition, the long carbon chain of the silanization agent and the structural filler of the amphiphilic surfactant can form stable and controllable structural units (the long carbon chain of the silanization agent and the hydrophobic group of the surfactant are close to each other and interact with each other by van der Waals force), thereby finely adjusting the expansion of the layer; or using a hard template agent with controllable size to play a role in space filling, so that the molecular sieve has an ordered mesoporous structure with controllable pore size (controlled by the chain length of the alkyl chain of the silanization agent); and then introducing a second template agent into the molecular sieve with open pores, and using the mechanism of dissolution-recrystallization to obtain a hierarchical pore Silicalite-1 molecular sieve.

[0132] In one embodiment, in step S1, the molar ratio of the silicon source: the first template agent: water: the silanization agent is 1:(0.01-2):(1-50):(0.02-0.2); and the weight ratio of SiO2 to the structural filler in the reaction mixture is (5-40):1.

[0133] In a preferred embodiment, in step S1, the molar ratio of the silicon source: the first template agent: water: the silanization agent is 1:(0.02-0.3):(5-30):(0.03-0.15); and the weight ratio of SiO2 to the structural filler in the reaction mixture is (5-30):1.

[0134] In one embodiment, in step S1, the silicon source is selected from at least one of organosilicone grease, solid silica gel, white carbon black and silica sol; preferably, it is selected from at least one of organosilicone grease, solid silica gel and white carbon black;

[0135] Further preferably, the organosilicone grease has a general structure as shown in the following formula (A):

[0136]

[0137] wherein R a , R b , R c , R d each independently is selected from an alkyl group having 1 to 6 carbon atoms, the alkyl group being a branched or straight chain alkyl group; preferably, R a , R b , R c , R d each independently is selected from a straight chain alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 4 carbon atoms; further preferably, the R a , R b , R c , R d each independently is selected from a methyl group, an ethyl group, a n-propyl group, an iso-propyl group, a n-butyl group, a sec-butyl group, an iso-butyl group or a tert-butyl group.

[0138] In a preferred embodiment, the organosilicon fat is selected from one or more of tetramethyl silicate, tetraethyl silicate, tetrabutyl silicate and dimethyldiethyl silicate.

[0139] In one embodiment, in step S1, the first template agent is an organic base, preferably at least one selected from a quaternary ammonium base, an aliphatic amine and an aliphatic alcohol amine.

[0140] In a particular embodiment, the first template agent is selected from at least one of the quaternary ammonium bases of the general formula (B) as shown below:

[0141] R1, R2, R3and R4are each selected from an alkyl group having 1 to 4 carbon atoms, preferably a straight chain alkyl group having 1 to 4 carbon atoms and a branched alkyl group having 3 to 4 carbon atoms, further preferably R1, R2, R3and R4are each selected from a methyl group, an ethyl group, a n-propyl group, an iso-propyl group, a n-butyl group, a sec-butyl group, an iso-butyl group or a tert-butyl group.

[0142] In a preferred embodiment, the first template agent is tetrapropyl ammonium hydroxide or is a mixture of tetrapropyl ammonium hydroxide with one or more selected from tetrapropyl ammonium chloride, tetrapropyl ammonium bromide.

[0143] In one embodiment, step S1 comprises:

[0144] a. mixing a silicon source, a first template agent and water to obtain a hydrolytic sol of silicon;

[0145] b. separately adding a silylating agent and a structure filler to the hydrolytic sol of silicon, and mixing to obtain the reaction mixture;

[0146] Optionally, the mixing in step a is performed under conditions including stirring at 40-90°C for 6-12h.

[0147] Optionally, the mixing in step b is performed under conditions including stirring at 20-50°C for 2-4h.

[0148] In one embodiment, the silicon source is an organosilicon grease, and after mixing the silicon source, the first template agent and water in step a, a hydrolytic alcohol-removing treatment is further performed to obtain the hydrolytic sol of silicon.

[0149] Optionally, the hydrolytic alcohol-removing treatment is performed under conditions including stirring hydrolysis at 40-90°C for 6-12h; preferably, stirring hydrolysis at 60-85°C for 8-10h. Preferably, the hydrolytic alcohol-removing treatment makes the mass content of alcohol produced by hydrolysis of the organosilicon grease in the hydrolytic sol of silicon be less than 10ppm.

[0150] In one embodiment, in step S1, the general formula of the silylating agent is R5Si(R6)(R7)R8, wherein R5, R6, R7, R8 are each independently halogen, alkyl, alkoxy, aryl, thiol or amine, and at least one of R5, R6, R7, R8 is alkyl, alkoxy, aryl, thiol or amine; the number of carbon atoms of the alkyl, alkoxy, thiol and amine is each independently C1-C30; and the number of carbon atoms of the aryl is C6-C30. 18 ;

[0151] Preferably, the silylating agent is selected from one or more of dimethyldichlorosilane, N-phenyl-3-aminopropyltrimethoxysilane, phenyltrimethoxysilane, 1,7-dichlorooctylmethyltetrasiloxane, hexadecyltrimethoxysilane, octyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane; further preferably, selected from one or more of N-phenyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

[0152] In one embodiment, in step S2, the conditions of the first hydrothermal crystallization treatment include a hydrothermal crystallization time of 0.25-7 days and a hydrothermal crystallization temperature of 130-200°C; and the pressure is autogenous pressure.

[0153] In step S2, the conditions of the first calcination treatment include a calcination temperature of 300-700°C and a calcination time of 1-16h.

[0154] In one preferred embodiment, in step S2, the conditions of the first hydrothermal crystallization treatment include a hydrothermal crystallization time of 1-3 days and a hydrothermal crystallization temperature of 150-180°C; and the pressure is autogenous pressure.

[0155] The conditions of the first calcination treatment in step S2 include a calcination temperature of 400-600°C and a calcination time of 2-5 h. The hierarchical porous Silicalite-1 molecular sieve prepared according to the present embodiment has better catalytic activity.

[0156] In a specific embodiment, after the first hydrothermal crystallization treatment, the product of the first hydrothermal crystallization treatment is subjected to a first filtration treatment and a first drying treatment, and then the first calcination treatment is performed. The temperature of the first drying treatment is 50-120°C, and the time is 1-12 h.

[0157] In an embodiment, in step S3, the second template agent is selected from the same range as the first template agent, which is not described again here; preferably, the first template agent and the second template agent are the same template agent.

[0158] In an embodiment, in step S3, the weight ratio of the molecular sieve intermediate, the second template agent and water is 1:(0.01-1.5):(1-15); preferably, it is 1:(0.1-1):(2-10). According to the preferred weight ratio in the present embodiment, a molecular sieve with higher catalytic activity can be obtained.

[0159] In an embodiment, in step S3, the conditions of the second hydrothermal crystallization treatment include a hydrothermal crystallization time of 0.25-7 days, a hydrothermal crystallization temperature of 130-200°C, and an autogenous pressure.

[0160] The conditions of the second calcination treatment in step S3 include a calcination temperature of 300-700°C and a calcination time of 1-16 h.

[0161] In a preferred embodiment, in step S3, the conditions of the second hydrothermal crystallization treatment include a hydrothermal crystallization time of 1-3 days, a hydrothermal crystallization temperature of 150-180°C, and an autogenous pressure.

[0162] The conditions of the second calcination treatment in step S3 include a calcination temperature of 400-600°C and a calcination time of 2-5 h.

[0163] In a specific embodiment, after the second hydrothermal crystallization treatment, the product of the second hydrothermal crystallization treatment is subjected to a second filtration treatment and a second drying treatment, and then the second calcination treatment is performed. The temperature of the second drying treatment is 50-120°C, and the time is 1-12 h.

[0164] The present disclosure is described in detail below through examples.

[0165] The sample was31 P-TMP MAS NMR characterization was obtained on an AVANCE III 600 WB type nuclear magnetic resonance spectrometer, using a 4 mm double resonance probe, a Ф4 mm ZrO2 rotor, a resonance frequency of 242.9 MHz, a magic angle rotation speed of 10 kHz, a pulse width of 1.4 μs, a recycle delay time of 1 s, and about 6000 scans.

[0166] X-ray diffraction (XRD) phase patterns of the sample were determined on a Siemens D5005 type X-ray diffractometer, with a Kα (Cu) radiation source, and a test range 2θ of 0.5° to 70°.

[0167] Transmission electron microscope (TEM) pictures of the sample were obtained on an FEI Tecnai G2 F20 S-TWIN type transmission electron microscope. The cavity structure and its size were obtained according to TEM electron microscope testing. The volume content of the cavity structure in the sample was obtained by measuring the transmission electron microscope (TEM) pictures: the volume of each cavity in the molecular sieve particles was measured according to the TEM pictures (the middle value of the sum of the maximum length and the minimum length passing through the center of the cavity structure was taken as the spherical diameter, and then the spherical radius was obtained, and then the percentage of the total volume of the cavities to the total volume of the molecular sieve particles was calculated; the average value was obtained after calculating the cavity structure volume fraction of 50 molecular sieve particles).

[0168] Scanning electron microscope (SEM) pictures of the sample were obtained on a Hitachi S4800 high-resolution cold field emission scanning electron microscope. The average particle size of the sample was tested by measuring the SEM electron microscope pictures (the average value was obtained after testing the particle sizes of 50 molecular sieve particles).

[0169] The total specific surface area and the total pore volume of the sample were determined on a Micromeritics ASAP 245 static nitrogen adsorption instrument according to the ASTM D4222-98 standard method. The adsorption isotherm and the desorption isotherm of the sample were determined according to the ASTM D4222-98 standard method.

[0170] Q 3 / Q 4 The measurement method uses 29 Si MAS NMR method, on an AVANCE III 500 WB type nuclear magnetic resonance spectrometer, using a 7 mm double resonance probe, a Ф7 mm ZrO2 rotor, a resonance frequency of 99.3 MHz, a rotation speed of 5 kHz, a pulse width of 1.8 μs, a recycle delay time of 2 s, and about 3000 scans.

[0171] Q 1H MAS NMR spectra were obtained on a Varian Infinityplus-400 spectrometer using a 4 mm double-resonance probe, a Ф4 mm ZrO2 rotor, a resonance frequency of 400.1 MHz, a magic angle spinning speed of 10 kHz, a pulse width of 3.57 μs, a recycle delay time of 1 s, and about 4000 scans.

[0172] The reagents used in the following examples and comparative examples of the present disclosure were all purchased through conventional channels.

[0173] Preparation Example 1

[0174] (1) 104 g of tetraethyl orthosilicate (0.5 mol), 65 g of a 25 wt% tetrapropylammonium hydroxide (TPAOH, 0.08 mol) aqueous solution, and 140 g of water (7.8 mol) were sequentially added into a 500 mL beaker, mixed uniformly on a magnetic stirrer with heating and stirring functions, and stirred at 60°C for 5 hours, with the evaporation of water being replenished in a timely manner, to obtain a colorless transparent silica gel solution;

[0175] (2) 9 g of N-phenyl-3-aminopropyltrimethoxysilane (PHAPTMS, 0.035 mol) and 3 g of a PEO-PPO-PEO triblock copolymer (P123, purchased from Innochem, with a weight average molecular weight of 5800) were added to the mixture of step (1) and stirred for 2 hours;

[0176] (3) The mixture obtained in step (2) was transferred into a stainless steel sealed autoclave, and crystallized at 170°C for 24 hours to obtain a sample. The obtained sample was filtered, washed, dried at 110°C for 3 hours, and then calcined at 550°C in a muffle furnace for 3 hours to obtain an intermediate product M-1.

[0177] (4) 10 g of the M-1 sample, 20 g of a 25 wt% tetrapropylammonium hydroxide (TPAOH, 5 g) aqueous solution, and 40 g of water were uniformly mixed (the weight ratio of the molecular sieve intermediate: the second template: water was 1:0.5:5.5), transferred into a stainless steel sealed autoclave, and crystallized at 170°C for 24 hours to obtain a sample. The obtained sample was filtered, washed, dried at 110°C for 3 hours, and then calcined at 550°C in a muffle furnace for 3 hours to obtain a hierarchical pore Silicalite-1 molecular sieve sample CAT-1.

[0178] The characterization results of the structure parameters of CAT-1 are listed in Table 2.

[0179] The TEM electron micrograph of CAT-1 is shown in FIG. 1, which shows that the molecular sieve has an intracrystalline multi-cavity hierarchical pore structure, and the size of the single cavity structure is 10-90 nm. Figure 1 ​

[0180] The TEM of the intermediate M-1 without dissolution recrystallization is shown in Figure 9 The TEM of the intermediate M-1 without dissolution recrystallization is shown in Figure 9 The TEM of the intermediate M-1 without dissolution recrystallization is shown in Figure 1 In comparison, it can be seen that Figure 1 The dissolution recrystallization treatment of the intermediate creates a large number of intracrystalline cavities;

[0181] The XRD spectrum of CAT-1 is shown in Figure 2 The XRD spectrum of CAT-1 is shown in

[0182] The XRD spectrum of CAT-1 is shown in 31 The P-TMP MAS NMR spectrum of CAT-1 is shown in Figure 3 The P-TMP MAS NMR spectrum of CAT-1 is shown in The P-TMP MAS NMR spectrum of CAT-1 is shown in The P-TMP MAS NMR spectrum of CAT-1 is shown in

[0183] The SEM image of CAT-1 is shown in Figure 4 The SEM image of CAT-1 is shown in

[0184] The BET of CAT-1 is shown in Figure 5 The BET of CAT-1 is shown in

[0185] The infrared hydroxyl spectrum of CAT-1 is shown in Figure 6 The infrared hydroxyl spectrum of CAT-1 is shown in -1 The infrared hydroxyl spectrum of CAT-1 is shown in -1 The infrared hydroxyl spectrum of CAT-1 is shown in -1 The infrared hydroxyl spectrum of CAT-1 is shown in

[0186] The Si MAS NMR spectrum of CAT-1 is shown in 29 The Si MAS NMR spectrum of CAT-1 is shown in Figure 7 The Si MAS NMR spectrum of CAT-1 is shown in Q3 Q is the peak area of the peak at chemical shift -113 ppm 4 X3 is calculated by formula (3) and listed in Table 3.

[0187] X1 of CAT-1 1 H MAS NMR spectrum and its peak separation results are shown in Figure 8 As can be seen from the figure, there are peaks at chemical shifts of 1.7 ppm, 2.0 ppm, 3.2 ppm and 4.5 ppm, and the corresponding peak areas A1-A4 are 60728, 87324, 65689 and 36591, respectively. The total area A0 of A1-A4 is 250332, and X1-X4 calculated by formula (4-1)-(4-4) are listed in Table 3. 4-1 4-4 X4 is calculated by formula (4-4) and listed in Table 3.

[0188] Preparation of Comparative Example 1

[0189] Referring to the method of Preparation Example 1, the difference between Preparation Example 1 is that no silanization reagent and structure filler are added, and the obtained product is denoted as DCAT-1. The preparation conditions are listed in Table 1, and the characterization results of the obtained molecular sieve are listed in Tables 2-3.

[0190] Preparation of Comparative Example 2

[0191] This preparation example is to prepare a conventional all-silicon Silicalite-1 molecular sieve according to the method disclosed in patent CN1338427A, which specifically comprises the following steps:

[0192] (1) 104 g of tetraethyl silicate, 90 g of a 22.5 wt% tetrapropylammonium hydroxide (TPAOH) aqueous solution, and 110 g of water were sequentially added to a 500 mL beaker, placed on a magnetic stirrer with heating and stirring functions, mixed uniformly, and stirred at 75°C for 5 hours, with water loss being replenished in a timely manner, to obtain a colorless transparent silica sol solution;

[0193] (2) The sol was transferred to a stainless steel sealed reaction kettle, and crystallized at 170°C for 2 days. After filtration and washing, it was dried at 120°C for 24 hours, and then calcined at 550°C in a muffle furnace for 5 hours.

[0194] (3) 15 g of the calcined product was mixed with 55 g of a 22.5 wt% tetrapropylammonium hydroxide (TPAOH) aqueous solution, and crystallized at 170°C for 1 day. After filtration and washing, it was dried at 110°C for 12 hours, and then calcined at 550°C in a muffle furnace for 4 hours. The obtained product is denoted as DCAT-2. The characterization results of the obtained molecular sieve are shown in Tables 2-3. The TEM of DCAT-2 is shown in Figure 12 ​As shown in the figure, it can be seen that the DCAT-2 molecular sieve does not have intracrystalline cavity structure.

[0195] Preparation Examples 2-9

[0196] The hierarchical porous Silicalite-1 molecular sieve catalyst was prepared according to the method of Preparation Example 1, except that the ratio and the synthesis conditions were changed, and the hierarchical porous Silicalite-1 molecular sieve sample was recorded as CAT-2-CAT-9; the preparation conditions are listed in Table 1, and the characterization results of the obtained molecular sieve are listed in Tables 2-3.

[0197] Preparation Example 10

[0198] The hierarchical porous Silialite-2 molecular sieve was prepared according to the method of Preparation Example 1, except that the template was changed, and the template used was tetrabutylammonium hydroxide (TBAOH), and the MEL topology was prepared, and the hierarchical porous molecular sieve sample was recorded as CAT-10; the preparation conditions are listed in Table 1, and the characterization results of the obtained molecular sieve are listed in Tables 2-3. The XRD of CAT-10 is shown in Figure 10 As shown in the figure, it can be seen that the DCAT-2 molecular sieve does not have intracrystalline cavity structure.

[0199] Preparation Example 11

[0200] The hierarchical porous β molecular sieve was prepared according to the method of Preparation Example 1, except that the ratio and the template were changed, and the template used was tetraethylammonium hydroxide (TEAOH), and the BEA topology was prepared, and the hierarchical porous molecular sieve sample was recorded as CAT-11; the preparation conditions are listed in Table 1, and the characterization results of the obtained molecular sieve are listed in Tables 2-3. The XRD of CAT-11 is shown in Figure 11 As shown in the figure, it can be seen that the DCAT-2 molecular sieve does not have intracrystalline cavity structure.

[0201] Preparation Example 12

[0202] The hierarchical porous Silicalite-1 molecular sieve was prepared according to the method of Preparation Example 1, except that the ratio and the template were changed, and the template used was tetraethylammonium hydroxide (TEAOH), and the BEA topology was prepared, and the hierarchical porous molecular sieve sample was recorded as CAT-11; the preparation conditions are listed in Table 1, and the characterization results of the obtained molecular sieve are listed in Tables 2-3. The XRD of CAT-11 is shown in

[0203] The temperature of the first hydrothermal crystallization treatment was 130°C, and the time was 4 days; the temperature of the first calcination treatment was 350°C, and the time was 8h;

[0204] The temperature of the second hydrothermal crystallization treatment was 130°C, and the time was 4 days; the temperature of the second calcination treatment was 350°C, and the time was 8h;

[0205] The hierarchical porous Silicalite-1 molecular sieve sample was recorded as CAT-12; the characterization results of the obtained molecular sieve are listed in Tables 2-3.

[0206] Table 1

[0207]

[0208]

[0209] In Table 1, TPAOH is tetrapropylammonium hydroxide, TBAOH is tetrabutylammonium hydroxide, TEAOH is tetraethylammonium hydroxide; PHAPTMS is N-phenyl-3- aminopropyltrimethoxysilane, APTMS is 3-aminopropyltriethoxysilane, GCPMS is 3- glycidoxypropyl(dimethoxy)methylsilane, TOMS is methyltrimethoxysilane; P123 is PEO- PPO-PEO triblock copolymer, CTAB is cetyltrimethylammonium bromide. The reagents used in the present disclosure can be obtained through conventional purchase channels;

[0210] In the calculation of water in Table 1, the water also includes the water from the first template aqueous solution; in the calculation of water in Table 1, the water also includes the water from the second template aqueous solution.

[0211] Table 2

[0212]

[0213] Table 3

[0214]

[0215] Reaction Example 1

[0216] The present reaction example is used to illustrate the effect of the method provided by the present disclosure for preparing adiponitrile.

[0217] The samples prepared in the above preparation examples and comparative examples are used as catalysts for preparing adiponitrile, and the evaluation device is a normal-pressure continuous-flow fixed-bed reactor, the inner diameter of the reactor is 5 mm, and the loading amount of the catalyst is 2 g. After loading the catalyst, the catalyst is pretreated in a nitrogen atmosphere at normal pressure and 350°C for 3 hours. The concentration of the raw material cyclohexanone oxime is 10% by weight, the solvent is methanol (the molar ratio of cyclohexanone oxime to solvent is 1:10), and the ammonia source is 25% by weight ammonia water. The reaction conditions include: the weight hourly space velocity (WHSV, the flow rate of cyclohexanone oxime in the feedstock / the weight of the catalyst in the reactor) of cyclohexanone oxime is 1 h -1 -1, the weight ratio of methanol to pure ammonia in ammonia water is 2000, the reaction temperature is 380°C, the reaction pressure is 0.8 MPa, the nitrogen flow rate is 4 L / h, and the reaction time is 12 h. The catalyst is repeatedly used for 5 times of the same catalytic reaction.

[0218] The cooled reaction product was collected, and the concentrations of each substance were quantitatively analyzed using a gas chromatograph (model 6890, Agilent) with an HP-5 column. The test conditions included a vaporizer temperature of 250°C, a detector temperature of 230°C, and a column temperature programmed to increase from 110°C to 230°C at a rate of 15°C / min, with a constant temperature of 230°C for 14 min. The results are shown in Table 4.

[0219] wherein the cyclohexanone oxime conversion rate % = (moles of cyclohexanone oxime in the raw material - moles of cyclohexanone oxime in the product) / moles of cyclohexanone oxime in the raw material x 100%;

[0220] The adiponitrile selectivity % = moles of adiponitrile in the product / (moles of cyclohexanone oxime in the raw material - moles of cyclohexanone oxime in the product) x 100%;

[0221] The cyclohexanone oxime conversion rate reduction % = (cyclohexanone oxime conversion rate after 1 reaction - cyclohexanone oxime conversion rate after 5 reactions) / cyclohexanone oxime conversion rate after 1 reaction x 100%;

[0222] The adiponitrile selectivity reduction % = (adiponitrile selectivity after 1 reaction - adiponitrile selectivity after 5 reactions) / adiponitrile selectivity after 1 reaction x 100%.

[0223] Table 4

[0224]

[0225]

[0226] As can be seen from the above table, compared with the catalytic reactions using DCAT-1 and DCAT-2, the molecular sieves CAT-1 to CAT-12 prepared according to the present disclosure can be used as catalysts in the catalytic reaction of cyclohexanone oxime and an ammonia source to prepare adiponitrile, and can obtain higher cyclohexanone oxime conversion rate and adiponitrile selectivity, and the molecular sieves have higher catalytic stability under multiple reaction conditions.

[0227] Further, comparing CAT-1 with CAT-9, it can be seen that the molecular sieve CAT-1 prepared according to the raw material addition ratio of “molar ratio of silicon source: first template agent: water: silylating agent is 1: (0.02-0.3): (5-30): (0.03-0.15); weight ratio of SiO2 to structure filler in the reaction mixture is (5-30): 1” and “weight ratio of molecular sieve intermediate, second template agent and water is 1: (0.1-1): (2-10)” can obtain higher cyclohexanone oxime conversion rate and adiponitrile selectivity, and the catalyst has better catalytic stability.

[0228] Further comparison between CAT-1 and CAT-12 shows that the molecular sieve CAT-1 prepared in Preparation Example 1 according to the preferred process conditions of the present disclosure can achieve higher conversion of cyclohexanone oxime and selectivity of adiponitrile, and the catalytic stability of the catalyst is better.

[0229] Reaction Comparative Example 1

[0230] The present comparative example uses the method disclosed in prior art CN112409210A to prepare adiponitrile, which specifically includes:

[0231] (1) The composition of ferric chloride: chromium nitrate: silicon carbide is 5:12:100, and the ferric chloride and chromium nitrate are dissolved by stirring after being dissolved in water to the same volume as the silicon carbide. The silicon carbide is immersed in the mixed solution containing the catalyst precursor to the same volume, and then placed for 12 hours. The catalyst for preparing adiponitrile is prepared by drying at 115°C and calcining at 600°C for 5 hours under nitrogen atmosphere.

[0232] (2) The reaction is carried out in a continuous flow fixed bed reactor, and the catalyst loading is 10 ml. The reducing medium is hydrogen, the reduction temperature is 450°C, the reduction pressure is normal pressure, and the reduction time is 6h. The preparation conditions are as follows: the volume ratio of acrylonitrile to N-methylpyrrolidone is 1.5:10, the space velocity is 1.5h -1 , the reaction temperature is 25°C, and the reaction pressure is normal pressure. The reaction results include: the conversion of acrylonitrile is 80.7 mol% and the selectivity of adiponitrile is 85.2 mol%. Comparison between Reaction Comparative Example 1 and Reaction Example 1 shows that the method provided by the present disclosure can achieve higher conversion of raw materials and selectivity of reaction products.

[0233] Reaction Examples 2-3

[0234] The same reaction device as in Reaction Example 1 is used, and the difference from Reaction Example 1 is that the reaction conditions are changed, and the catalytic reaction is carried out according to the reaction conditions listed in Table 5 below. The reaction results are listed in Table 6.

[0235] Table 5

[0236]

[0237] Table 6

[0238]

[0239]

[0240] From the above Tables 5-6, it can be seen that:

[0241] Comparing reaction example 3 with reaction example 1, it can be seen that when CAT-1 is used as the catalyst, reaction example 1 can achieve higher conversion of cyclohexanone oxime and selectivity of adiponitrile under the reaction conditions of "the weight ratio of the ammonia source calculated based on pure ammonia to the solvent is 1:(1000-2000); the reaction temperature is 350-400℃; the reaction time is 10-24h; the reaction pressure is 0.1-2MPa; the weight space velocity of the cyclohexanone oxime is 0.3-13h -1 -1".

[0242] The preferred embodiments of the present disclosure are described in detail above, but the present disclosure is not limited to the specific details in the above-described embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

[0243] In addition, it should be noted that each specific technical feature described in the above-described specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, various possible combinations are not described again in the present disclosure.

[0244] In addition, any combination of various different embodiments of the present disclosure can also be made, as long as it does not deviate from the idea of the present disclosure, and it should also be considered as disclosed by the present disclosure.

Claims

1. A process for the preparation of adiponitrile, characterized in that, The method comprises the following steps: contacting cyclohexanone oxime, an ammonia source and a catalyst to perform a catalytic reaction; The catalyst comprises a hierarchical pore Silicalite-1 molecular sieve, and the hierarchical pore Silicalite-1 molecular sieve has a plurality of cavity structures in the crystal.

2. The method of claim 1, wherein, The method further comprises: contacting cyclohexanone oxime, an ammonia source and a catalyst in the presence of a solvent to perform an intramolecular rearrangement and ring-opening cyano reaction.

3. The method of claim 2, wherein, The solvent is selected from one or more of methanol, ethanol, propanol, butanol and cyclohexanol; and the ammonia source is selected from ammonia water or ammonia gas.

4. The method of claim 3, wherein, The ammonia source is ammonia water with a concentration of 25-30 wt%.

5. The method of claim 2, wherein, The molar ratio of cyclohexanone oxime to solvent is 1:(3-50); and the weight ratio of the ammonia source to solvent, calculated based on pure ammonia, is 1:(10-5000).

6. The method of claim 5, wherein, The molar ratio of cyclohexanone oxime to solvent is 1:(5-30); and the weight ratio of the ammonia source to solvent, calculated based on pure ammonia, is 1:(50-4000).

7. The method of claim 1, wherein, The conditions of the catalytic reaction include: the reaction temperature is 200-450℃; the reaction time is 1-72h; the reaction pressure is 0.1-3MPa; the weight hourly space velocity of the cyclohexanone oxime is 0.1-15h -1 .

8. The method of claim 7, wherein, The conditions of the catalytic reaction include: the reaction temperature is 350-400℃; the reaction time is 10-24h; the reaction pressure is 0.1-2MPa; the weight hourly space velocity of the cyclohexanone oxime is 0.3-13h -1 .

9. The method of claim 1, wherein, The reactor for the catalytic reaction is selected from any one of a fixed bed reactor, a tank reactor, a moving bed reactor, a suspended bed reactor or a slurry bed reactor.

10. The method of claim 1, wherein, In the hierarchical pore Silicalite-1 molecular sieve, the size of a single cavity structure is 5-150 nm.

11. The method of claim 10, wherein, In the hierarchical pore Silicalite-1 molecular sieve, the size of a single cavity structure is 10-100 nm.

12. The method of claim 1, wherein, The volume of all the cavity structures accounts for 10-95% of the total volume of the molecular sieve.

13. The method of claim 12, wherein, The volume of all the cavity structures accounts for 15-90% of the total volume of the molecular sieve.

14. The method of claim 1, wherein, The shape of the cavity structure is selected from one or more of a spherical shape, a cubic shape, an ellipsoidal shape and an irregular cubic shape.

15. The method of claim 1, wherein, The hierarchical-pore Silicalite-1 molecular sieve has the following 31 P MAS NMR signature: The peak intensity of the characteristic peak at a chemical shift of -5±1 ppm of the hierarchical pore Silicalite-1 molecular sieve is denoted as N1; the peak intensity of the characteristic peak at a chemical shift of -34±1 ppm of the hierarchical pore Silicalite-1 molecular sieve is denoted as N2; and the peak intensity of the characteristic peak at a chemical shift of -61±1 ppm of the hierarchical pore Silicalite-1 molecular sieve is denoted as N3. X1 defined in the following formula (1) is any value between 0.10 and 0.30; X1=N1 / N3 formula (1); and X2 defined in the following formula (2) is any value between 0.15 and 0.45; X2=N2 / N3 formula (2).

16. The method of claim 15, wherein, X1 is any value between 0.15 and 0.25; and X2 is any value between 0.20 and 0.

35.

17. The method of claim 1, wherein, The hierarchical-pore Silicalite-1 molecular sieve has the following 29 Si MAS NMR characteristics: The peak area of the peak of the chemical shift in the range of -102 to -104 ppm of the hierarchical porous Silicalite-1 molecular sieve is denoted as Q 3 The peak area of the peak of the chemical shift in the range of -112 to -114 ppm is denoted as Q 4 X3 is any number between 2 and 30% as defined by the following equation (3): X3= Q 3 / Q 4 x 100% of formula (3).

18. The method of claim 17, wherein, X3 is any value between 5 and 25%.

19. The method of claim 1, wherein, The hierarchical-pore Silicalite-1 molecular sieve has the following 1 H MAS NMR characteristics: in the multi-level pore Silicalite-1 molecular sieve 1 In the peak separation result of the spectrum peak in the 1~6ppm chemical shift range of the H MAS NMR spectrum: the peak area of the spectrum peak in the 1.6~1.8ppm chemical shift range is recorded as A1, the peak area of the spectrum peak in the 2.0~2.2ppm chemical shift range is recorded as A2, the peak area of the spectrum peak in the 3.1~3.3ppm chemical shift range is recorded as A3, the peak area of the spectrum peak in the 4.4~4.6ppm chemical shift range is recorded as A4, and the sum of the A1~A4 peak areas is recorded as A0; X as defined in formula (4-1) below 4-1 any value between 14 and 32%: X 4-1 = A1 / A0 x 100% Equation (4-1); X as defined in formula (4-2) below 4-2 any value between 23 and 41 %: X 4-2 = A2 / A0 x 100% Equation (4-2); X as defined in formula (4-3) below 4-3 any value between 16 and 35%: X 4-3 = A3 / A0 x 100% Equation (4-3); X as defined in formula (4-4) below 4-4 any value between 4 and 20%: X 4-4 = A4 / A0 x 100% Equation (4-4).

20. The method of claim 1, wherein, The hierarchical pore Silicalite-1 molecular sieve comprises a molecular sieve particle composed of a single crystal grain and / or a molecular sieve particle composed of a plurality of aggregated crystal grains.

21. The method of claim 20, wherein, The average particle diameter of the molecular sieve particles is 0.1 to 2 μm; the BET specific surface area is 300 to 650 m 2 / g; the micropore specific surface area is 200 to 550 m 2 / g; the total pore volume is 0.2 to 0.7 cm 3 / g; the mesopore volume is 0.1 to 0.5 cm 3 / g.

22. The method of claim 21, wherein, The average particle diameter of the molecular sieve particles is 0.2 to 1.2 μm; the BET specific surface area is 350 to 550 m 2 / g; the micropore specific surface area is 250 to 450 m 2 / g; the total pore volume is 0.3 to 0.5 cm 3 / g; the mesopore volume is 0.2 to 0.4 cm 3 / g.

23. The method of claim 1, wherein, The hierarchical pore Silicalite-1 molecular sieve has a hysteresis loop between the adsorption isotherm and the desorption isotherm of low-temperature nitrogen adsorption.

24. The method of claim 1, wherein, The hierarchical pore Silicalite-1 molecular sieve is prepared by a preparation method comprising the following steps: S1, mixing a silicon source, a first template agent, water, a silylation agent and a structure filler to obtain a reaction mixture, wherein the structure filler is an amphiphilic surfactant and / or a hard template agent; S2, sequentially performing a first hydrothermal crystallization treatment and a first calcination treatment on the reaction mixture to obtain a molecular sieve intermediate; S3, mixing the molecular sieve intermediate, a second template agent and water, and then sequentially performing a second hydrothermal crystallization treatment and a second calcination treatment.

25. The method of claim 24, wherein, In step S1, the molar ratio of the silicon source: the first template agent: water: the silylation agent is 1: (0.01-2): (1-50): (0.02-0.2); and the weight ratio of SiO2 to the structure filler in the reaction mixture is (5-40):

1.

26. The method of claim 25, wherein, In step S1, the molar ratio of the silicon source: the first template agent: water: the silylation agent is 1: (0.02-0.3): (5-30): (0.03-0.15); and the weight ratio of SiO2 to the structure filler in the reaction mixture is (5-30):

1.

27. The method of claim 24, wherein, In step S1, the silicon source is selected from at least one of organic silicon grease, solid silica gel, white carbon black and silica sol.

28. The method of claim 27, wherein, In step S1, the silicon source is selected from at least one of organic silicon grease, solid silica gel and white carbon black.

29. The method of claim 28, wherein, In step S1, the silicon source is selected from organic silicon grease, and the general formula of the organic silicon grease is shown in the following formula (A): （A）； wherein R a , R b , R c , R d each independently is selected from an alkyl group having 1 to 6 carbon atoms, the alkyl group being a branched or straight chain alkyl group.

30. The method of claim 29, wherein, In formula (A), R a , R b , R c , R d each independently is selected from a linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 4 carbon atoms.

31. The method of claim 30, wherein, In formula (A), the R a , R b , R c , R d each independently is selected from methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, i-butyl or t-butyl.

32. The method of claim 30, wherein, In formula (A), the organic silicon grease is selected from one or more of tetramethyl silicate, tetraethyl silicate, tetrabutyl silicate and dimethyl diethyl silicon grease.

33. The method of claim 24, wherein, The first template agent in step S1 and the second template agent in step S3 are organic bases.

34. The method of claim 33, wherein, The first template agent in step S1 and the second template agent in step S3 are each independently selected from at least one of quaternary ammonium base, aliphatic amine and aliphatic alcohol amine.

35. The method of claim 34, wherein, The first template agent and the second template agent are each independently selected from at least one of quaternary ammonium base having the structure shown in the following formula (B): （B）； R1, R2, R3 and R4 are each selected from alkyl having 1-4 carbon atoms.

36. The method of claim 35, wherein, In formula (B), R1, R2, R3 and R4 are each selected from linear alkyl having 1-4 carbon atoms and branched alkyl having 3-4 carbon atoms.

37. The method of claim 36, wherein, In formula (B), R1, R2, R3 and R4 are each selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl and tert-butyl.

38. The method of claim 35, wherein, The first template agent and the second template agent are each independently tetrapropyl ammonium hydroxide or a mixture of tetrapropyl ammonium hydroxide and one or more selected from tetrapropyl ammonium chloride and tetrapropyl ammonium bromide.

39. The method of claim 24, wherein, In step S1, the silylation agent is selected from one or more of dimethyl dichlorosilane, N-phenyl-3-aminopropyl trimethoxysilane, phenyl trimethoxysilane, 1,7-dichlorooctylmethyl tetrasiloxane, hexadecyl trimethoxysilane, octyl triethoxysilane, 3-aminopropyl trimethoxysilane, N-β-(aminoethyl)-γ-aminopropyl trimethoxysilane and 3-mercaptopropyl trimethoxysilane.

40. The method of claim 39, wherein, The silanization agent is selected from one or more of N-phenyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

41. The method of claim 24, wherein, In step S1, the structure filler is selected from one or more of cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, PEO-PPO-PEO triblock copolymer, mesoporous carbon, and natural cellulose.

42. The method of claim 24, wherein, Step S1 comprises: a. mixing a silicon source, a first template agent, and water to obtain a hydrolytic sol of silicon; b. adding a silanization agent and a structure filler to the hydrolytic sol of silicon respectively, and mixing to obtain the reaction mixture.

43. The method of claim 42, wherein, The mixing conditions in step a. include stirring at 40-90°C for 6-12h; and the mixing conditions in step b. include stirring at 20-50°C for 2-4h.

44. The method of claim 42, wherein, The silicon source is an organosilicon grease, and after mixing the silicon source, the first template agent, and water in step a., a hydrolytic alcohol-removing treatment is further included to obtain the hydrolytic sol of silicon.

45. The method of claim 44, wherein, The conditions of the hydrolytic alcohol-removing treatment include stirring hydrolysis at 40-90°C for 6-12h.

46. The method of claim 45, wherein, The conditions of the hydrolytic alcohol-removing treatment include stirring hydrolysis at 60-85°C for 8-10h.

47. The method of claim 24, wherein, In step S3, the weight ratio of the molecular sieve intermediate: second template agent: water is 1:(0.01-1.5):(1-15).

48. The method of claim 47, wherein, In step S3, the weight ratio of the molecular sieve intermediate: second template agent: water is 1:(0.1-1):(2-10).

49. The method of claim 24, wherein, The conditions of the first hydrothermal crystallization treatment in step S2 and the second hydrothermal crystallization treatment in step S3 each independently include a hydrothermal crystallization time of 0.25-7 days and a hydrothermal crystallization temperature of 130-200°C; and the pressure is autogenous pressure. The conditions of the first calcination treatment in step S2 and the second calcination treatment in step S3 each independently include a calcination temperature of 300-700°C and a calcination time of 1-16h.

50. The method of claim 49, wherein, The conditions of the first hydrothermal crystallization treatment in step S2 and the second hydrothermal crystallization treatment in step S3 each independently include a hydrothermal crystallization time of 1-3 days and a hydrothermal crystallization temperature of 150-180°C. The conditions of the first calcination treatment in step S2 and the second calcination treatment in step S3 each independently include a calcination temperature of 400-600°C and a calcination time of 2-5h.

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