A titanium silicon molecular sieve and its preparation method and application

Abstract

The present invention relates to a titanium silicon molecular sieve and its preparation method and application. The silicon-titanium molar ratio Si / Ti of the Ti-MOR molecular sieve of the present invention is 80-200; the silicon-aluminum molar ratio Si / Al is 200-500; the wave number in the FT-IR spectrum of the Ti-MOR molecular sieve is 3400-3700 cm ‑1 Peak area S 3400～3700 With a wave number of 1880 cm ‑1 Peak area S 1880 The ratio is 0.15 to 0.25. The titanium silicalite molecular sieve exhibits excellent catalytic performance in the ammoxidation reaction of aldehydes and ketones.

Description

Technical Field

[0001] The invention belongs to the field of catalysis and relates to a titanium silicon molecular sieve and a preparation method and application thereof. Background Art

[0002] Mercerized molecular sieve (MOR) has attracted considerable attention due to its unique pore properties (octahedral pores parallel to the c-axis, straight 12-membered pores, and octahedral pores parallel to the b-axis). Ti-MOR molecular sieves, prepared by implanting heteroatom Ti into the MOR topology, are a key member of the titanium silicate family. Ti-MOR molecular sieves exhibit excellent catalytic activity, product selectivity, and continuous reaction stability in selective catalytic oxidation reactions, particularly in the ammoxidation of organic aldehydes and ketones such as acetone, butanone, and acetaldehyde. Currently, a catalytic system using Ti-MOR molecular sieve as a catalyst and H₂O₂ as an oxidant has achieved industrial application in the ammoxidation of butanone to butanone oxime. Ti-MOR molecular sieves have also been gradually used in the preparation of a series of corresponding ketone oxime chemicals, such as the commodity chemical cyclohexanone oxime, replacing the less-performing TS-1 molecular sieve. In summary, Ti-MOR molecular sieves are an important catalyst with promising market prospects.

[0003] According to current reports, Ti-MOR molecular sieves cannot be directly synthesized through a hydrothermal system. Usually, the preparation method of Ti-MOR is an isomorphous substitution secondary synthesis method, that is, using a silicon-aluminum mercerized molecular sieve as the matrix, repeated high-temperature reflux acid washing is used to remove most of the Al atoms in the framework, and then TiCl4 vapor is used in a high-temperature inert N2 atmosphere for gas-solid isomorphous replacement, thereby implanting Ti atoms into the MOR molecular sieve framework in a four-coordinated state. In summary, during the preparation process of Ti-MOR molecular sieves, due to the large-scale removal of Al atoms, abundant silanol defect sites are formed. Although it can facilitate the entry of Ti atoms into the molecular sieve framework, it still leads to problems such as poor hydrophobicity and low crystallinity of the molecular sieve, which in turn affects the diffusion, adsorption and desorption of various organic substrate molecules in the molecular sieve pores, thereby affecting the catalytic activity.

[0004] Yang et al. (J. Catal., 2014, 320, 160-169) used H2O or CH3OH as solvent and NH4F as fluorine source to post-treat the de-Alized Ti-MOR molecular sieve at 100°C. The performance of the modified Ti-MOR molecular sieve was improved. However, due to the presence of fluorine-containing compounds, silicon dissolution occurred in the molecular sieve during the modification process, which still affected the crystallinity and hydrophobicity of the molecular sieve. Summary of the Invention

[0005] The present invention addresses the problems of poor hydrophobicity and low crystallinity of existing Ti-MOR molecular sieves by providing a titanium silicate molecular sieve, its preparation method, and application. This titanium silicate molecular sieve exhibits excellent hydrophobicity and high crystallinity, and exhibits excellent catalytic performance in the ammoxidation of aldehydes and ketones.

[0006] The first aspect of the present invention provides a Ti-MOR molecular sieve, wherein the silicon-titanium molar ratio Si / Ti of the Ti-MOR molecular sieve is 80-200; the silicon-aluminum molar ratio Si / Al is 200-500; the wave number in the FT-IR spectrum of the Ti-MOR molecular sieve is 3400-3700 cm -1 Peak area S 3400～3700 With a wave number of 1880 cm -1 Peak area S 1880 The ratio of S 3400～3700 / S 1880 It is 0.15~0.25.

[0007] According to the present invention, the relative crystallinity of the Ti-MOR molecular sieve is 110% to 125%.

[0008] A second aspect of the present invention provides a method for preparing the above-mentioned Ti-MOR molecular sieve, the preparation method comprising the following steps:

[0009] (1) Mixing Ti-MOR molecular sieve raw powder and organic amine solution uniformly for pretreatment;

[0010] (2) drying the pretreated product obtained in step (1) under an oxygen-free gas purge;

[0011] (3) The dried product obtained in step (2) is crystallized in an alcohol solution containing an ammonium salt.

[0012] According to the present invention, the organic amine in step (1) is an organic amine having 1 to 3 carbon atoms; further, the organic amine is a primary amine, preferably at least one of methylamine, ethylamine, and n-propylamine. The molar concentration of the organic amine solution is 0.01 to 1 mol / L.

[0013] According to the present invention, the Ti-MOR molecular sieve raw powder in step (1) can be prepared according to conventional methods. In the FT-IR spectrum of the Ti-MOR molecular sieve raw powder in step (1), the wave number is 3400-3700 cm -1 Peak area S 3400～3700 With a wave number of 1880 cm -1 Peak area S 1880The ratio is greater than 1.0 and can be 1.0 to 1.8. Preferably, the silicon-titanium molar ratio Si / Ti of the Ti-MOR molecular sieve raw powder is 80 to 200, the silicon-aluminum molar ratio Si / Al is 100 to 500; the specific surface area is 450 to 600 m 2 / g; pore volume 0.25~0.5mL / g; particle size is (800~1000)×(180~200)×(200~250)nm. The mass ratio of the molecular sieve raw powder and the organic amine solution in step (1) is 1:10~25. The mixing can be carried out under stirring, and the stirring time is 0.5~5h. The pretreatment device is a reactor. The pretreatment method is soaking. The pretreatment temperature is 60~120℃, and the time is 2~24h. After the pretreatment is completed, solid-liquid separation is carried out. The solid-liquid separation is preferably filtration and / or centrifugation. The solid obtained by separation is the pretreatment product.

[0014] According to the present invention, the oxygen-free gas in step (2) is at least one of nitrogen and inert gas. The volume space velocity of the oxygen-free gas is 100 to 200 h -1 The temperature of the purging treatment is 80-120°C and the time is 2-6 hours. The purging and drying treatment can be carried out in a quartz tube.

[0015] According to the present invention, in the mixed system of the dried product in step (3) and the alcohol solution containing ammonium salt, the mass ratio of the dried product in step (2): ammonium salt: alcohol is 1:2-25:10-20; the ammonium salt is at least one of an inorganic ammonium salt and an organic ammonium salt; preferably at least one of ammonium chloride, ammonium fluoride, tetramethylammonium bromide, tetraethylammonium bromide and tetrapropylammonium bromide; the alcohol is an alcohol having 1 to 4 carbon atoms, preferably at least one of methanol, ethanol, tert-butanol and isopropanol.

[0016] According to the present invention, in step (3), the mixing of the dried product obtained in step (2) and the alcohol solution containing ammonium salt can be carried out under stirring, and the stirring time is 0.5 to 5 hours. The temperature of the crystallization treatment is 80 to 200°C, and the crystallization time is 1 to 3 days. The crystallization is preferably dynamic crystallization, and the rotation speed of the dynamic crystallization is 10 to 100 rpm. The crystallization treatment can be carried out in a homogeneous reactor. The solid product obtained after the crystallization treatment is preferably dried and calcined. The drying conditions are a temperature of 80 to 150°C and a time of 12 to 24 hours. The calcination treatment is a conventional method. The calcination conditions are a temperature of 500 to 600°C and a time of 5 to 8 hours.

[0017] A third aspect of the present invention provides use of the Ti-MOR molecular sieve or the Ti-MOR molecular sieve prepared by the above preparation method in the ammoxidation reaction of aldehydes and ketones.

[0018] According to the present invention, the aldehyde and ketone compound is at least one of acetone, butanone, cyclohexanone and acetaldehyde, preferably cyclohexanone.

[0019] According to the present invention, the reaction raw materials include aldehydes and ketones, hydrogen peroxide, ammonia, and a solvent; the solvent is tert-butyl alcohol. Preferably, the molar ratio of the aldehydes and ketones, hydrogen peroxide, and NH₃·H₂O in the reaction raw material mixture is 1:1.0-1.5:1.0-2.0. The amount of the solvent added is 5-12 times the mass of the aldehydes and ketones. The amount of the molecular sieve added is 10%-20% of the mass of the aldehydes and ketones.

[0020] According to the present invention, the temperature of the ammoxidation reaction is 40-80° C., the reaction pressure is 0.1-0.3 MPa, and the reaction time is 0.5-2 h.

[0021] Compared with the prior art, the present invention has the following advantages

[0022] (1) In the present invention, the silicon-titanium molar ratio Si / Ti of the Ti-MOR molecular sieve is 80-200; the silicon-aluminum molar ratio Si / Al is 200-500; after FT-IR spectrum analysis, the S of the Ti-MOR molecular sieve is 3400～3700 / S 1880 The value is 0.15~0.25, the S of Ti-MOR raw powder 3400～3700 / S 1880 The molecular sieve of the present invention has good hydrophobicity, especially high crystallinity, and exhibits excellent catalytic performance in the ammoxidation reaction of aldehyde and ketone organic compounds, that is, the molecular sieve catalyst has high catalytic reaction activity and high selectivity for the target product.

[0023] (2) In the present invention, the Ti-MOR molecular sieve raw powder is first pretreated in an organic amine solution, then dried at high temperature under an oxygen-free gas purge, and finally crystallized in an alcohol solution containing ammonium salt to obtain the Ti-MOR molecular sieve. In the present invention, the use of an organic amine solution for pretreatment in the preparation method is conducive to further removal of aluminum atoms in the skeleton and partial repair of defect sites in the molecular sieve. The high-temperature drying with an oxygen-free gas in step (2) of the preparation method can remove physically adsorbed water molecules and crystallization water in the molecular sieve, break the combination of crystallization water and defect sites, and then expose the hydroxyl defect sites in the molecular sieve, which is conducive to subsequent further crystallization treatment. The molecular sieve prepared by the organic amine solution pretreatment, high-temperature drying and crystallization treatment in an alcohol solution containing ammonium salt in the method of the present invention has the characteristics of good hydrophobicity and high crystallinity, and exhibits excellent catalytic performance in the ammoxidation reaction of aldehyde and ketone organic compounds, that is, the molecular sieve catalyst has high catalytic reaction activity and high selectivity of the target product. The operation of the present invention is simple and convenient, and the process is easy to control and repeat. Organic amines, ammonium salts and alcohols are inexpensive and readily available, and can be easily subjected to large-scale post-processing modifications.

[0024] (3) In the present invention, the Ti-MOR molecular sieve exhibits excellent catalytic performance in the ammoxidation of aldehydes and ketones. Specifically, the molecular sieve catalyst exhibits high catalytic activity and high selectivity for the desired product. Cyclohexanone conversion (reaching ≥85%) and cyclohexanone oxime selectivity (reaching ≥99.4%) are both high, demonstrating high performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The XRD spectra of Example 1, Comparative Example 1 and Ti-MOR molecular sieve raw powder are shown below:

[0026] Figure 2 The following are Fourier transform infrared (FT-IR) spectra of Example 1, Comparative Example 1 and Ti-MOR molecular sieve raw powder;

[0027] Figure 3 The XRD spectra of the molecular sieves of Examples 2 to 4 and Comparative Examples 2 and 3 are shown;

[0028] Figure 4 The following are Fourier transform infrared (FT-IR) spectra of the molecular sieves of Examples 2 to 4 and Comparative Examples 2 and 3. DETAILED DESCRIPTION

[0029] In the present invention, the Ti-MOR molecular sieve powder with MOR structure in each example was prepared according to the method disclosed in the reference (J. Phys. Chem, 1996, 100, 10316-10322). The obtained Ti-MOR molecular sieve powder had a silicon-titanium molar ratio Si / Ti of 82 and a silicon-aluminum molar ratio Si / Al of 120; a specific surface area of ​​545 m2 / g, pore volume 0.334mL / g, and average particle size 1000×200×200nm.

[0030] In the present invention, the contents of Al and Ti in the molecular sieve are analyzed and determined by plasma atomic emission spectrometry (Thermo IRIS Intrepid II).

[0031] In the present invention, the relative crystallinity of the molecular sieve is analyzed using a Shimadzu XRD 6000 X-ray powder diffractometer. The relative crystallinity of the sample is determined by taking the ratio of the sum of the peak areas of the six characteristic peaks of 2Theta at 5-10° and 25-30° in the XRD pattern of each molecular sieve to the sum of the corresponding characteristic peak areas of the Ti-MOR molecular sieve raw powder in step (1) of Example 1. The larger the value, the better the crystallinity. In the following preparation methods, the Ti-MOR molecular sieve raw powder is 100%.

[0032] In the present invention, the hydrophobic properties of Ti-MOR molecular sieves were analyzed and determined by referring to the method disclosed in the literature (Catal. Sci. Technol., 2020, 10, 2905-2915). In the Fourier transform infrared spectrum of the sample, the wave number is 3400-3700 cm -1 Peak area S 3400～3700 With a wave number of 1880 cm -1 Peak area S 1880 The ratio (ie S 3400～3700 / S 1880 ) is used to represent the hydrophobicity of the molecular sieve. The smaller the ratio, the better the hydrophobicity, and the larger the ratio, the worse the hydrophobicity. 3400～3700 / S 1880 The value is 1.2.

[0033] Example 1

[0034] (1) The Ti-MOR molecular sieve raw powder was pretreated with an ethylamine aqueous solution. The Ti-MOR molecular sieve raw powder and the ethylamine aqueous solution were mixed evenly according to the stoichiometric ratio. The mixing was carried out under stirring at 25°C for 2 hours. The mass ratio of the Ti-MOR molecular sieve raw powder and the ethylamine aqueous solution was 1:10, and the concentration of the ethylamine aqueous solution was 0.1 mol / L. After mixing evenly, the mixture was transferred to a reactor and heated to 120°C for 12 hours. After the mixture was mixed evenly, the solid obtained by filtration and centrifugation was the pretreated product, recorded as Ti-MOR-ea-1.

[0035] (2) The obtained Ti-MOR-ea-1 sample was subjected to high temperature drying. The Ti-MOR-ea-1 was transferred to a quartz tube and nitrogen was introduced to replace the air in the tube. The volumetric space velocity of the nitrogen was 100 h-1 After heating to 100°C for 3 h, the sample Ti-MOR-dry-1 was obtained by cooling to room temperature (25°C).

[0036] (3) Post-treatment of the obtained Ti-MOR-dry-1 sample. Ti-MOR-dry-1, an additive and an alcohol were mixed, and the mass ratio of Ti-MOR-dry-1: additive: alcohol in the mixture was 1:10:20. The additive was tetraethylammonium bromide and the alcohol was methanol. The mixture was stirred at 25°C for 1 hour, then transferred to a reactor, loaded into a homogeneous reactor, heated to 100°C, and started dynamic post-treatment at a speed of 20 rpm for 1 day. After the treatment was completed, the mixture was centrifuged to obtain the corresponding solid product, and the obtained solid product was placed in a 100°C oven for drying for 12 hours, then transferred to a muffle furnace and calcined at 550°C for 6 hours to remove the tetraethylammonium bromide and methanol remaining in the molecular sieve pores, and the final molecular sieve catalyst product Ti-MOR-1 was obtained.

[0037] Analysis shows that the silicon-titanium molar ratio Si / Ti of the Ti-MOR-1 molecular sieve is 80; the silicon-aluminum molar ratio Si / Al is 200. The relative crystallinity of Ti-MOR-1 is 120%. 3400～3700 / S 1880 The value is 0.18. The molecular sieve prepared by the present invention has good hydrophobicity and high crystallinity. The XRD patterns of the prepared titanium silicon molecular sieve and Ti-MOR molecular sieve raw powder are shown in Figure 1 , infrared spectrum see Figure 2 .

[0038] Example 2

[0039] (1) The Ti-MOR molecular sieve raw powder is pretreated with an aqueous solution of n-propylamine. The Ti-MOR molecular sieve raw powder and the n-propylamine aqueous solution are mixed evenly according to the stoichiometric ratio. The mixing is carried out under stirring at 25°C for 2 hours. The mass ratio of the Ti-MOR molecular sieve raw powder and the n-propylamine aqueous solution is 1:15, and the concentration of the n-propylamine aqueous solution is 0.8 mol / L. After mixing evenly, the mixture is transferred to a reactor and heated to 120°C for 12 hours. After completion, the solid obtained by filtration and centrifugation is the pretreated product, recorded as Ti-MOR-ea-2.

[0040] (2) The obtained Ti-MOR-ea-2 sample was subjected to high temperature drying. The Ti-MOR-ea-2 was transferred to a quartz tube and nitrogen was introduced to replace the air in the tube. The volume space velocity of the nitrogen was 100 h -1 After heating to 80°C and treating for 4 hours, the sample Ti-MOR-dry-2 was obtained by cooling to room temperature (25°C).

[0041] (3) Post-processing the obtained Ti-MOR-dry-2 sample. Ti-MOR-dry-2, an additive and an alcohol were mixed, and the mass ratio of Ti-MOR-dry-2: additive: alcohol in the mixture was 1:15:15. The additive was tetramethylammonium bromide and the alcohol was ethanol. The mixture was stirred at 25°C for 1 hour, then transferred to a reactor, loaded into a homogeneous reactor, heated to 100°C, and started dynamic post-processing at a speed of 20 rpm for 1 day. After the treatment was completed, the mixture was centrifuged to obtain the corresponding solid product, and the obtained solid product was placed in a 100°C oven for drying for 12 hours, then transferred to a muffle furnace and calcined at 550°C for 6 hours to remove the additive and alcohol remaining in the molecular sieve pores, and the final molecular sieve catalyst product Ti-MOR-2 was obtained.

[0042] Analysis shows that the silicon-titanium molar ratio Si / Ti of the Ti-MOR-2 molecular sieve is 82; the silicon-aluminum molar ratio Si / Al is 210. The relative crystallinity of Ti-MOR-1 is 115%. 3400～3700 / S 1880 The value is 0.21.

[0043] The XRD pattern of the prepared titanium silicate molecular sieve is shown in Figure 3 , infrared spectrum see Figure 4 .

[0044] Example 3

[0045] (1) Pre-treat the Ti-MOR molecular sieve raw powder with a methylamine aqueous solution. Mix the Ti-MOR molecular sieve raw powder and the methylamine aqueous solution evenly according to the stoichiometric ratio. The mixing is carried out under stirring at 25°C for 2 hours. The mass ratio of the Ti-MOR molecular sieve raw powder to the methylamine aqueous solution is 1:20, and the concentration of the methylamine aqueous solution is 0.5 mol / L. After uniform mixing, transfer it to a reactor and heat it to 120°C for 12 hours. After completion, the solid obtained by filtration and centrifugation is the pre-treated product, recorded as Ti-MOR-ea-3.

[0046] (2) The obtained Ti-MOR-ea-3 sample was subjected to high temperature drying treatment. The Ti-MOR-ea-3 was transferred to a quartz tube and nitrogen was introduced to replace the air in the tube. The volume space velocity of the nitrogen was 100 h -1 After heating to 100°C for 4 hours, the sample Ti-MOR-dry-3 was obtained by cooling to room temperature (25°C).

[0047] (3) The obtained Ti-MOR-dry-3 sample was post-treated. Ti-MOR-dry-3, an additive and an alcohol were mixed, and the mass ratio of Ti-MOR-dry-3: additive: alcohol in the mixture was 1:20:20. The additive was ammonium chloride and the alcohol was tert-butyl alcohol. The above mixture was stirred at 25°C for 1 hour, then transferred to a reactor, loaded into a homogeneous reactor, heated to 100°C, and started dynamic post-treatment at a speed of 20 rpm for 1 day. After the treatment was completed, the mixture was centrifuged to obtain the corresponding solid product, and the above solid product was placed in a 100°C oven for drying for 12 hours, then transferred to a muffle furnace and calcined at 550°C for 6 hours to remove the additive and alcohol remaining in the molecular sieve pores, and the final molecular sieve catalyst product Ti-MOR-3 was obtained.

[0048] Analysis shows that the silicon-titanium molar ratio Si / Ti of the Ti-MOR-3 molecular sieve is 82; the silicon-aluminum molar ratio Si / Al is 250. The relative crystallinity of Ti-MOR-1 is 110%. 3400～3700 / S 1880 The value is 0.22.

[0049] The XRD pattern of the prepared titanium silicate molecular sieve is shown in Figure 3 , infrared spectrum see Figure 4 .

[0050] Example 4

[0051] (1) The Ti-MOR molecular sieve raw powder was pretreated with an ethylamine aqueous solution. The Ti-MOR molecular sieve raw powder and the ethylamine aqueous solution were mixed evenly according to the stoichiometric ratio. The mixing was carried out under stirring at 25°C for 2 hours. The mass ratio of the Ti-MOR molecular sieve raw powder and the ethylamine aqueous solution was 1:10, and the concentration of the ethylamine aqueous solution was 0.1 mol / L. After mixing evenly, the mixture was transferred to a reactor and heated to 120°C for 12 hours. After the mixture was mixed evenly, the solid obtained by filtration and centrifugation was the pretreated product, recorded as Ti-MOR-ea-4.

[0052] (2) The obtained Ti-MOR-ea-4 sample was subjected to high temperature drying treatment. The Ti-MOR-ea-4 was transferred to a quartz tube and nitrogen was introduced to replace the air in the tube. The volume space velocity of the nitrogen was 100 h -1 After heating to 100°C for 3 h, the sample Ti-MOR-dry-4 was obtained by cooling to room temperature (25°C).

[0053] (3) Post-treatment of the obtained Ti-MOR-dry-4 sample. Ti-MOR-dry-4, an additive and an alcohol were mixed, and the mass ratio of Ti-MOR-dry-4: additive: alcohol in the mixture was 1:20:20. The additive was a mixed solution of tetraethylammonium bromide and tetrapropylammonium bromide, wherein the weight ratio of tetraethylammonium bromide and tetrapropylammonium bromide was 1:1, and the alcohol was methanol. The above mixture was stirred at 25°C for 1 hour, then transferred to a reactor, loaded into a homogeneous reactor, heated to 100°C, and started dynamic post-treatment at a speed of 20 rpm for 1 day. After the treatment was completed, the mixture was centrifuged to obtain the corresponding solid product, and the above solid product was placed in a 100°C oven for drying for 12 hours, then transferred to a muffle furnace and calcined at 550°C for 6 hours to remove the additive and alcohol remaining in the molecular sieve pores, and the final molecular sieve catalyst product Ti-MOR-4 was obtained.

[0054] Analysis shows that the silicon-titanium molar ratio Si / Ti of the Ti-MOR-4 molecular sieve is 84; the silicon-aluminum molar ratio Si / Al is 210. The relative crystallinity of Ti-MOR-4 is 122%. 3400～3700 / S 1880 The value is 0.17.

[0055] The XRD pattern of the prepared titanium silicate molecular sieve is shown in Figure 3 , infrared spectrum see Figure 4 .

[0056] Comparative Example 1

[0057] (1) The Ti-MOR molecular sieve raw powder is subjected to high temperature drying treatment. The Ti-MOR raw powder is placed in a quartz tube, and nitrogen is introduced to replace the air in the tube. The volume space velocity of the nitrogen is 100h -1 After heating to 100°C for 3 h, the sample Ti-MOR-dry-D1 was obtained by cooling to room temperature (25°C).

[0058] (2) Post-process the obtained Ti-MOR-dry-D1 sample. Ti-MOR-dry-D1, an additive and an alcohol were mixed, and the mass ratio of Ti-MOR-dry-D1: additive: alcohol in the mixture was 1:10:20. The additive was tetraethylammonium bromide and the alcohol was methanol. The above mixture was stirred at 25°C for 1 hour, then transferred into a reactor, loaded into a homogeneous reactor, heated to 100°C, and started dynamic post-processing at a speed of 20 rpm for 1 day. After the treatment was completed, the mixture was centrifuged to obtain the corresponding solid product, and the above solid product was placed in a 100°C oven for drying for 12 hours, then transferred to a muffle furnace and calcined at 550°C for 6 hours to obtain the final molecular sieve catalyst product Ti-MOR-D1.

[0059] Analysis shows that the silicon-titanium molar ratio Si / Ti of the Ti-MOR-D1 molecular sieve is 85; the silicon-aluminum molar ratio Si / Al is 155. The relative crystallinity of Ti-MOR-D1 is 80%. 3400～3700 / S 1880 The value is 1.41.

[0060] The XRD pattern of the prepared titanium silicate molecular sieve is shown in Figure 1 , infrared spectrum see Figure 2 .

[0061] Comparative Example 2

[0062] (1) The Ti-MOR molecular sieve raw powder is pretreated with an aqueous solution of n-propylamine. The Ti-MOR molecular sieve raw powder and the n-propylamine aqueous solution are mixed evenly according to the stoichiometric ratio. The mixing is carried out under stirring at 25°C for 2 hours. The mass ratio of the Ti-MOR molecular sieve raw powder and the n-propylamine aqueous solution is 1:15, and the concentration of the n-propylamine aqueous solution is 0.8 mol / L. After mixing evenly, the mixture is transferred to a reactor and heated to 120°C for 12 hours. After completion, the solid obtained by filtration and centrifugation is the pretreatment product, recorded as Ti-MOR-ea-D2.

[0063] (2) Drying the Ti-MOR-ea-D2 sample: Transfer the Ti-MOR-ea-D2 to an oven, dry it at 45°C for 4 h, and then cool it to room temperature (25°C) to obtain the Ti-MOR-dry-D2 sample.

[0064] (3) Post-treatment of the obtained Ti-MOR-dry-D2 sample. Ti-MOR-dry-D2, an additive and an alcohol were mixed, and the mass ratio of Ti-MOR-dry-D2: additive: alcohol in the mixture was 1:15:15. The additive was tetramethylammonium bromide and the alcohol was ethanol. The mixture was stirred at 25°C for 1 hour, then transferred to a reactor, loaded into a homogeneous reactor, heated to 100°C, and started dynamic post-treatment at a speed of 20 rpm for 1 day. After the treatment was completed, the mixture was centrifuged to obtain the corresponding solid product, and the obtained solid product was placed in a 100°C oven for drying for 12 hours, then transferred to a muffle furnace and calcined at 550°C for 6 hours to remove the additive and alcohol remaining in the molecular sieve pores, and the final molecular sieve catalyst product Ti-MOR-D2 was obtained.

[0065] Analysis shows that the silicon-titanium molar ratio Si / Ti of the Ti-MOR-D2 molecular sieve is 86; the silicon-aluminum molar ratio Si / Al is 210. The relative crystallinity of Ti-MOR-D2 is 95%. 3400～3700 / S1880 The value is 1.11.

[0066] The XRD pattern of the prepared titanium silicate molecular sieve is shown in Figure 3 , infrared spectrum see Figure 4 .

[0067] Comparative Example 3

[0068] (1) Pre-treat the Ti-MOR molecular sieve raw powder with a methylamine aqueous solution. Mix the Ti-MOR molecular sieve raw powder and the methylamine aqueous solution evenly according to the stoichiometric ratio. The mixing is carried out under stirring at 25°C for 2 hours. The mass ratio of the Ti-MOR molecular sieve raw powder to the methylamine aqueous solution is 1:20, and the concentration of the methylamine aqueous solution is 0.5 mol / L. After uniform mixing, transfer it to a reactor and heat it to 120°C for 12 hours. After completion, the solid obtained by filtration and centrifugation is the pre-treated product, recorded as Ti-MOR-ea-D3.

[0069] (2) The obtained Ti-MOR-ea-D3 sample was subjected to high temperature drying. The Ti-MOR-ea-D3 was transferred to a quartz tube and nitrogen was introduced to replace the air in the tube. The volume space velocity of the nitrogen was 100 h -1 After heating to 100°C and treating for 4 hours, the sample Ti-MOR-D3 was obtained by cooling to room temperature (25°C).

[0070] Analysis shows that the silicon-titanium molar ratio Si / Ti of the Ti-MOR-D3 molecular sieve is 88; the silicon-aluminum molar ratio Si / Al is 235. The relative crystallinity of Ti-MOR-D3 is 90%. 3400～3700 / S 1880 The value is 1.28.

[0071] The XRD pattern of the prepared titanium silicate molecular sieve is shown in Figure 3 , infrared spectrum see Figure 4 .

[0072] Test Case

[0073] The catalytic activity and stability of Ti-MOR molecular sieve powder and the molecular sieves prepared in various examples and comparative examples were evaluated using the ammoxidation of cyclohexanone. The reaction process in this example involved adding Ti-MOR molecular sieve, solvent, cyclohexanone, oxidant, and aqueous ammonia (25% aqueous ammonia solution) to a reaction tube using 85% tert-butanol as the solvent and 31% hydrogen peroxide as the oxidant. The reaction was conducted at 0.15 MPa and 60°C for 1 hour. The molecular sieve was added at a concentration of 15% of the mass of the cyclohexanone. The tert-butanol solvent was 5 times the mass of the cyclohexanone. The molar ratio of cyclohexanone: H₂O₂:NH₃·H₂O in the raw materials was 1:1.1:1.7. The specific reaction results are shown in Tables 1 and 2.

[0074] Table 1 Test results of reaction for 1h

[0075] Molecular sieve catalysts Cyclohexanone conversion, wt% Cyclohexanone oxime selectivity, wt% Ti-MOR raw powder 80.2 99.5 Ti-MOR-1 86.6 99.5 Ti-MOR-2 85.3 99.4 Ti-MOR-3 88.7 99.8 Ti-MOR-4 90.1 99.7 Ti-MOR-D1 60.1 99.2 Ti-MOR-D2 67.3 99.1 Ti-MOR-D3 62.4 99.1

Claims

1. A Ti-MOR molecular sieve, characterized in that: The silicon-titanium molar ratio Si / Ti of the Ti-MOR molecular sieve is 80-200; the silicon-aluminum molar ratio Si / Al is 200-500; the wave number in the FT-IR spectrum of the Ti-MOR molecular sieve is 3400-3700 cm -1 Peak area S 3400~3700 With a wave number of 1880 cm -1 Peak area S 1880 The ratio is 0.15~0.

25.

2. The Ti-MOR molecular sieve according to claim 1, characterized in that The relative crystallinity of the Ti-MOR molecular sieve is 110% to 125%.

3. A method for preparing the molecular sieve according to any one of claims 1 to 2, comprising the steps of: (1) Mix the Ti-MOR molecular sieve raw powder and the organic amine solution evenly for pretreatment; (2) drying the pretreated product obtained in step (1) under an oxygen-free gas purge; (3) The dried product obtained in step (2) is crystallized in an alcohol solution containing an ammonium salt.

4. The preparation method according to claim 3, characterized in that The organic amine in step (1) is an organic amine having 1 to 3 carbon atoms; and / or the molar concentration of the organic amine solution in step (1) is 0.01 to 1 mol / L.

5. The preparation method according to claim 4, characterized in that: The organic amine in step (1) is at least one of methylamine, ethylamine and n-propylamine.

6. The preparation method according to claim 3, characterized in that: In the FT-IR spectrum of the Ti-MOR molecular sieve raw powder in step (1), the wave number is 3400~3700cm -1 Peak area S 3400~3700 With a wave number of 1880 cm -1 Peak area S 1880 The ratio is above 1.

0.

7. The preparation method according to claim 6, characterized in that: In the FT-IR spectrum of the Ti-MOR molecular sieve raw powder in step (1), the wave number is 3400~3700cm -1 Peak area S 3400~3700 With a wave number of 1880 cm -1 Peak area S 1880 The ratio is 1.0~1.

8.

8. The preparation method according to claim 3 or 6, characterized in that: The silicon-titanium molar ratio Si / Ti of the Ti-MOR molecular sieve raw powder in step (1) is 80-200; the silicon-aluminum molar ratio Si / Al is 100-500; and the specific surface area is 450-600m 2 / g, pore volume is 0.25~0.5mL / g; particle size is (800~1000)×(180~200)×(200~250)nm.

9. The preparation method according to claim 3, characterized in that: The mass ratio of the molecular sieve raw powder to the organic amine solution in step (1) is 1:10-25; the pretreatment method in step (1) is soaking; the pretreatment temperature is 60-120° C., and the time is 2-24 hours.

10. The preparation method according to claim 3, characterized in that: The oxygen-free gas in step (2) is at least one of nitrogen and inert gas; the volume space velocity of the oxygen-free gas in step (2) is 100-200h -1 ; and / or, the temperature of the purging treatment in step (2) is 80~120℃ and the time is 2~6h.

11. The preparation method according to claim 3, characterized in that: In the mixed system of the dried product in step (3) and the alcohol solution containing ammonium salt, the mass ratio of the dried product in step (2): ammonium salt: alcohol is 1:2-25:10-20; and / or, the ammonium salt in step (3) is at least one of ammonium chloride, ammonium fluoride, tetramethylammonium bromide, tetraethylammonium bromide and tetrapropylammonium bromide; And / or, the alcohol in step (3) is an alcohol having 1 to 4 carbon atoms.

12. The preparation method according to claim 11, characterized in that: The alcohol in step (3) is at least one of methanol, ethanol, tert-butanol and isopropanol.

13. The preparation method according to claim 3, characterized in that: The temperature of the crystallization treatment in step (3) is 80-200° C., and the crystallization time is 1-3 days.

14. Use of the molecular sieve according to any one of claims 1 to 2 or the molecular sieve prepared by the preparation method according to any one of claims 3 to 13 in the ammoxidation reaction of aldehydes and ketones.

15. The use according to claim 14, characterized in that The aldehyde and ketone organic compound is at least one of acetone, butanone, cyclohexanone, and acetaldehyde; the raw materials for the ammoxidation reaction include the aldehyde and ketone organic compound, hydrogen peroxide, ammonia, and a solvent; and the solvent is tert-butanol.

16. The use according to claim 15, characterized in that The aldehyde and ketone organic compound is cyclohexanone; the molar ratio of the aldehyde and ketone organic compound, hydrogen peroxide, and NH3·H2O in the mixed system of the reaction raw materials is 1:1.0-1.5:1.0-2.0; the added amount of the solvent is 5-12 times the mass of the aldehyde and ketone organic compound; and the added amount of the molecular sieve is 10%-20% of the mass of the aldehyde and ketone organic compound.

17. The use according to claim 14 or 15, characterized in that The temperature of the ammoxidation reaction is 40-80°C; the reaction pressure is 0.1-0.3 MPa; and the reaction time is 0.5-2 h.

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