A fully crystallized ti-mww molecular sieve catalyst, a preparation method and application thereof

Abstract

This invention discloses a fully crystalline Ti-MWW molecular sieve catalyst, its preparation method, and its applications. The UV-Raman spectrum of the fully crystalline Ti-MWW molecular sieve catalyst is at 343±4 cm⁻¹. ‑1 484±4cm ‑1 699±4cm ‑1 and 1097±4cm ‑1 A spectral peak appears at 699±4cm. ‑1 The intensity of the spectral peak is 343±4 cm⁻¹. ‑1 The peak intensity is 0.5 to 10 times that of the spectral peak, 1097 ± 4 cm⁻¹ ‑1 The intensity of the spectral peak is 343±4 cm⁻¹. ‑1 The spectral peak intensity is 0.5 to 10 times that of the standard. The Ti-MWW molecular sieve catalyst, when used in olefin epoxidation reactions, exhibits high olefin conversion, high epoxide selectivity, and good catalytic stability.

Description

Technical Field

[0001] This invention relates to a fully crystalline Ti-MWW molecular sieve catalyst, its preparation method, and its application, belonging to the field of molecular sieve catalysts. Background Technology

[0002] Epoxides are important organic chemical raw materials, mainly including ethylene oxide, propylene oxide, 1,2-epoxypentane, and 1,2-epoxyhexane. Currently, epoxides are primarily produced through the selective oxidation of olefins. For example, ethylene oxide is obtained by epoxidation of ethylene with air in the presence of a silver catalyst; the industrial production routes for propylene oxide mainly include the chlorohydrin process and the co-oxidation process. The former is gradually being phased out due to severe environmental pollution, while the latter has a long process flow and high construction investment. Since the yield of co-products is almost 2 to 4 times that of propylene oxide, the market demand for co-products has a significant impact on this process; the industrial production method for 1,2-epoxypentane and 1,2-epoxyhexane is the organic peroxyacid oxidation method for 1-pentene and 1-hexene, which suffers from severe equipment corrosion, high risk, and poor atom economy.

[0003] In the 1980s, EniChem developed a new method for producing propylene oxide, the hydrogen peroxide oxidation (HPPO) process (US4410501). This process uses TS-1 molecular sieves with an MFI structure as a catalyst, reacting propylene with hydrogen peroxide in methanol to produce propylene oxide. This process is environmentally friendly and has high raw material utilization, and has been industrialized. However, the approximately 0.5 nm ten-ring pores hinder diffusion, posing a significant challenge to the epoxidation of cyclohexene, which has a slightly larger molecular size. To address this, Professor Wu Peng and others developed a new generation of titanium-silicon molecular sieve, Ti-MWW (Journal of Catalysis, 2001, 202, 245). Compared to TS-1 molecular sieves, Ti-MWW molecular sieves not only have higher olefin conversion rates but also better selectivity for epoxides. Therefore, developing efficient olefin epoxidation processes based on Ti-MWW molecular sieves is of great significance.

[0004] Currently, the industrial production of propylene oxide is mainly carried out in fixed-bed reactors. However, the micron- or nano-sized titanium silicate molecular sieve powder produced by the hydrothermal method has low inherent strength and is easily entrained by the reaction liquid during the reaction, causing blockages in the equipment's pipelines. Furthermore, separating and recovering the titanium silicate molecular sieve powder from the reaction liquid after the reaction is also very difficult. To ensure efficient and continuous fixed-bed reactions, it is necessary to prepare titanium silicate molecular sieve powder into catalysts with good mechanical strength. CN1346705A proposes using small spheres with a certain mechanical strength as a carrier, and enriching the titanium silicate molecular sieve on its surface through spheroidization to improve the catalyst's mechanical strength. CN1268400A proposes using alumina as a carrier to prepare titanium silicate molecular sieve catalysts that meet industrial application requirements. CN103464197B proposes mixing TS-1 molecular sieve with oxides, followed by alkali treatment to improve the catalyst's mechanical strength.

[0005] While adding inert binders to pre-formed titanium-silicon molecular sieve catalysts can improve their mechanical strength, it also reduces the overall proportion of active components, blocks some pores, decreases micropore volume, restricts substrate diffusion, reduces catalyst activity, and makes them more susceptible to carbon deposition and deactivation. To eliminate the negative effects of binders, CN112354557A discloses a method for preparing a monolithic titanium zeolite catalyst and its application. This method involves mixing an amorphous silica-based binder and a polymeric pore-forming agent into MWW titanium zeolite powder, adding water, stirring and kneading, mechanically shaping and calcining, then immersing it in an aqueous solution of a composite cyclic nitrogen-containing organic compound, sealing and heating, and finally filtering, drying, and calcining to obtain a monolithic propylene continuous epoxidation catalyst. Although no binder is present, the catalyst's catalytic performance remains low, with a mechanical strength of less than 30 N / cm, making it unsuitable for industrial applications. Furthermore, the complex structure and high cost of the composite cyclic nitrogen-containing organic compound used in its preparation result in extremely high production costs, hindering large-scale industrial production.

[0006] In summary, existing Ti-MWW molecular sieve catalysts, regardless of whether they contain binders, suffer from low mechanical strength and poor catalytic performance. There is a need to develop Ti-MWW molecular sieve catalysts with high mechanical strength and good catalytic performance. Summary of the Invention

[0007] One of the technical problems to be solved by this invention is to address the issues of poor titanium species state, low mechanical strength, and poor catalytic performance in existing Ti-MWW molecular sieve catalysts, and to provide a fully crystalline Ti-MWW molecular sieve catalyst. This catalyst features good titanium species state, high mechanical strength, and excellent catalytic performance.

[0008] The second technical problem to be solved by this invention is to address the current lack of a method for preparing Ti-MWW molecular sieve catalysts with good titanium species state, high mechanical strength, and excellent catalytic performance, and to provide a method for preparing fully crystalline Ti-MWW molecular sieve catalysts.

[0009] The third technical problem to be solved by this invention is to provide an application of a fully crystalline Ti-MWW molecular sieve catalyst in the epoxidation reaction of olefins.

[0010] To address one of the aforementioned technical problems, the first aspect of this invention provides a fully crystalline Ti-MWW molecular sieve catalyst, the ultraviolet-Raman spectrum of which is within the range of 343±4 cm⁻¹. -1 484±4cm -1 699±4cm -1 and 1097±4cm -1 A spectral peak appears at 699±4cm. -1 The intensity of the spectral peak is 343±4 cm⁻¹. -1 The peak intensity is 0.5 to 10 times, preferably 2 to 10 times, at 1097 ± 4 cm⁻¹. -1 The intensity of the spectral peak is 343±4 cm⁻¹. -1 The intensity of the spectral peak is 0.5 to 10 times, preferably 2 to 10 times.

[0011] According to the present invention, further, in the molecular sieve catalyst, the silicon-to-titanium molar ratio (n) is [value missing] on an atomic basis. Si / n Ti The value is 10 to 200, preferably 25 to 100.

[0012] According to the present invention, the molecular sieve catalyst further comprises at least one element selected from boron and aluminum, preferably boron. In the molecular sieve catalyst, the boron-silicon molar ratio (n) is [value missing] on an atomic basis. B / n Si The aluminum-silicon molar ratio (n) is 0 to 0.1, preferably 0 to 0.03, and more preferably 0.005 to 0.03; on an atomic basis, the aluminum-silicon molar ratio (n) is... Al / n Si The value is 0 to 0.1, preferably 0 to 0.03.

[0013] According to the present invention, the micropore volume of the molecular sieve catalyst is further defined as 0.03–0.15 cm³. 3 / g, preferably 0.03~0.12cm 3 / g, more preferably 0.05~0.10cm 3 / g; the proportion of micropore volume to total pore volume is 1% to 7.5%, preferably 1% to 6%, and more preferably 1.7% to 5%.

[0014] According to the present invention, the mechanical strength of the molecular sieve catalyst is further 30-90 N / cm, preferably 40-80 N / cm.

[0015] To address the second technical problem mentioned above, a second aspect of the present invention provides a method for preparing a fully crystalline Ti-MWW molecular sieve catalyst, comprising the following steps:

[0016] (1) Ti-MWW molecular sieve powder, binder, pore-forming agent and fluoride are kneaded into a molded shape and calcined to obtain the molded product;

[0017] (2) The molded product from step (1) is crystallized in an environment containing an organic amine solution to obtain catalyst precursor A;

[0018] (3) The catalyst precursor A from step (2) was treated with an acid solution and calcined to obtain catalyst precursor B;

[0019] (4) The catalyst precursor B from step (3) is treated with an organic amine solution to obtain the molecular sieve catalyst.

[0020] According to the present invention, the Ti-MWW molecular sieve powder in step (1) has a silicon-to-titanium molar ratio of 5 to 120 on an atomic basis.

[0021] According to the present invention, further, the binder in step (1) is an amorphous binder, comprising a silicon source and at least one selected from boron and aluminum sources; preferably, the amorphous binder comprises a silicon source and a boron source. In the binder composition, based on oxides, the molar ratio SiO2:B2O3:Al2O3 = 1:x:y, where x = 0–0.5, y = 0–0.5, and x+y = 0.02–1. The binder is prepared by uniformly mixing the various component raw materials.

[0022] According to the present invention, further, in the binder composition, the silicon source is selected from at least one of silica sol, water glass, silica, and tetraethyl orthosilicate; the boron source is selected from at least one of boric acid, boron trioxide, and borate; and the aluminum source is selected from at least one of aluminum trioxide, aluminum hydroxide, sodium aluminate, aluminum nitrate, and aluminum sulfate.

[0023] According to the present invention, further, the pore-forming agent in step (1) is selected from at least one of guar gum powder, cellulose, chitosan, lignin, starch, polyethylene glycol, triblock copolymer P123 and F127; the fluoride is selected from at least one of sodium fluoride, potassium fluoride and ammonium fluoride. The mass ratio of the raw materials in step (1), Ti-MWW molecular sieve powder, binder, pore-forming agent and fluoride is 1:0.1~1.5:0.01~0.1:0.01~0.4.

[0024] According to the present invention, further, in step (1), an appropriate amount of water can be added during the kneading and molding process as needed, and after kneading and molding, the mixture is dried and calcined. The drying conditions are 60-120℃ for 1-24 hours; the calcination conditions are 450-650℃ in an oxygen-containing atmosphere for 4-12 hours.

[0025] According to the present invention, the specific process of crystallization in step (2) under an organic amine solution environment is as follows: In step (1), the molded article is placed above the organic amine solution for crystallization, and the molded article does not come into contact with the organic amine solution. The organic amine is at least one selected from piperidine and hexamethyleneimine; the concentration of the organic amine solution is 0.3-15 mol / L; the mass ratio of the molded article to the organic amine solution is 0.1-10:1. The crystallization conditions are: crystallization in a closed environment under autogenous pressure, crystallization temperature of 130-190℃, and crystallization time of 1-9 days.

[0026] According to the present invention, the crystallized product in step (2) is further washed and dried. The drying conditions are 60–120°C for 1–24 hours. The catalyst precursor A in step (2) does not involve calcination.

[0027] According to the present invention, further, the acid solution treatment process in step (3) includes: step (2) reacting the catalyst precursor A with the acid solution. The acid solution is selected from at least one of nitric acid, hydrochloric acid, sulfuric acid, formic acid, acetic acid, or oxalic acid solution; the concentration of the acid solution is 0.3–12 mol / L; the solid-liquid mass ratio of the catalyst precursor A to the acid solution is 1:10–80. The conditions for the acid solution treatment are: a treatment temperature of 60–130°C and a treatment time of 4–48 hours.

[0028] According to the present invention, the product after acid solution treatment in step (3) is further subjected to washing, drying and calcination. The drying conditions are 60-120°C for 1-24 hours; the calcination conditions are calcination at 450-650°C in an oxygen-containing atmosphere for 4-12 hours.

[0029] According to the present invention, further, the organic amine solution treatment process in step (4) includes: step (3) reacting catalyst precursor B with fluoride and organic amine solution. The fluoride is selected from at least one of sodium fluoride, potassium fluoride and ammonium fluoride; the organic amine is selected from at least one of piperidine and hexamethyleneimine; the concentration of the organic amine solution is 0.3-15 mol / L; the mass ratio of catalyst precursor B, fluoride and organic amine solution is 1:0.05-0.4:2-20. The conditions for the organic amine solution treatment are: treatment temperature of 130-190°C and treatment time of 4-48 hours.

[0030] According to the present invention, the product after organic amine solution treatment in step (4) is further washed and dried. The drying conditions are 60–120°C for 1–24 hours. The preparation of the molecular sieve catalyst in step (4) does not involve calcination.

[0031] According to the present invention, the molecular sieve catalyst in step (4) further comprises at least one element selected from boron and aluminum. The silicon-titanium molar ratio is 10–200, preferably 25–100, on an atomic basis; the boron-silicon molar ratio is 0–0.1, preferably 0–0.03, more preferably 0.005–0.03, on an atomic basis; and the aluminum-silicon molar ratio is 0–0.1, preferably 0–0.05, on an atomic basis.

[0032] The present invention also provides a fully crystalline Ti-MWW molecular sieve catalyst prepared by the above method.

[0033] According to the present invention, further, in the ultraviolet Raman spectrum of the molecular sieve catalyst prepared by the method, at 343±4 cm⁻¹... -1 484±4cm -1 699±4cm -1 and 1097±4cm -1 A spectral peak appears at 699±4cm. -1 The intensity of the spectral peak is 343±4 cm⁻¹. -1 The peak intensity is 0.5 to 10 times, preferably 1 to 8 times, at 1097 ± 4 cm⁻¹. -1 The intensity of the spectral peak is 343±4 cm⁻¹. -1 The intensity of the spectral peak is 0.5 to 10 times, preferably 1 to 8 times.

[0034] According to the present invention, the molecular sieve catalyst prepared by the method further comprises a micropore volume of 0.03–0.15 cm³. 3 / g, preferably 0.03~0.12cm 3 / g, more preferably 0.05~0.10cm 3 / g; the proportion of micropore volume to total pore volume is 1% to 7.5%, preferably 1% to 6%, and more preferably 1.7% to 5%.

[0035] According to the present invention, the molecular sieve catalyst prepared by the method further has a mechanical strength of 30-90 N / cm, preferably 40-80 N / cm.

[0036] To address the third technical problem mentioned above, this invention provides an application of the aforementioned all-crystalline Ti-MWW molecular sieve catalyst in the epoxidation reaction of olefins.

[0037] According to the present invention, the application step further includes: mixing an olefin, an aqueous solution of hydrogen peroxide, a solvent, and at least one basic nitrogen-containing substance as a feed liquid, and reacting it with the catalyst. The reaction apparatus is a fixed-bed reactor.

[0038] According to the present invention, the olefin is a liquefied olefin; the olefin includes at least one selected from propylene, allyl chloride, butene, pentene, cyclopentene, hexene, and cyclohexene; the mass fraction of hydrogen peroxide in the hydrogen peroxide aqueous solution is 10% to 70%; the solvent is at least one selected from methanol, acetonitrile, propionitrile, acetone, and tert-butanol; and the basic nitrogen-containing substance is at least one selected from piperidine and hexamethyleneimine.

[0039] According to the present invention, further, in the raw material liquid, the molar ratio of olefin to hydrogen peroxide is 1:0.3-1; the olefin accounts for 1%-50% of the mass fraction of the raw material liquid; the solvent accounts for 30%-90% of the mass fraction of the raw material liquid; and the mass concentration of the alkaline nitrogen-containing substance in the raw material liquid is 1-50 ppm.

[0040] According to the present invention, the flow rate of the catalyst per unit mass of the feed liquid is further 3 to 30 mL·g. cat. -1 ·h -1 The reaction temperature is 30–100℃, and the reaction pressure is 0.1–4 MPa.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] 1. In this invention, the ultraviolet Raman spectrum of the fully crystalline Ti-MWW molecular sieve catalyst is at 343±4 cm⁻¹. -1 484±4cm -1 699±4cm -1 and 1097±4cm -1 A spectral peak appears at 699±4cm. -1 The intensity of the spectral peak is 343±4 cm⁻¹. -1 The peak intensity is 0.5 to 10 times that of the spectral peak, 1097 ± 4 cm⁻¹ -1 The intensity of the spectral peak is 343±4 cm⁻¹. -1 The peak intensity is 0.5 to 10 times that of the spectral peak. 343±4 cm⁻¹ -1 The spectral peak belongs to the MWW skeleton, 484±4 cm⁻¹ -1 1097±4cm -1 The spectral peak belongs to a four-coordinated titanium species in the framework, 699±4 cm⁻¹ -1 The spectral peaks belong to non-framework six-coordinate titanium species, all of which are catalytically active centers for olefin epoxidation. High intensity peak: 699±4 cm⁻¹ -1 1097±4cm-1 The presence of spectral peaks indicates the presence of a large number of well-formed titanium species, and the molecular sieve catalyst is free of amorphous binders and possesses high mechanical strength. When used in olefin epoxidation reactions, this molecular sieve catalyst exhibits high olefin conversion, high epoxide selectivity, and good catalytic stability.

[0043] 2. In this invention, the catalyst preparation method involves first adding fluoride, an amorphous binder, and a pore-forming agent during the molecular sieve forming process. Preferably, the amorphous binder includes a silicon source and a boron source. Then, the catalyst precursor A is crystallized in an organic amine solution environment to obtain catalyst precursor A. Next, catalyst precursor A is treated with an acid solution to obtain catalyst precursor B. Finally, catalyst precursor B is treated with an organic amine solution to obtain the catalyst. This invention's preparation method can efficiently convert the binder into a molecular sieve, improving mechanical strength and obtaining a fully crystalline molecular sieve catalyst precursor. The preparation method improves the titanium species state of the molecular sieve through two solution treatments, obtaining a fully crystalline Ti-MWW molecular sieve catalyst containing well-formed framework four-coordinate titanium species and non-framework six-coordinate titanium species, with high mechanical strength. The catalyst prepared by this invention exhibits excellent catalytic activity, selectivity, and stability in olefin epoxidation reactions.

[0044] 3. The catalyst of this invention exhibits excellent catalytic performance in olefin epoxidation reactions, with high olefin conversion, high epoxide selectivity, and good catalytic stability, demonstrating promising application prospects. Attached Figure Description

[0045] Figure 1 The UV-Raman spectrum of the all-crystalline Ti-MWW molecular sieve catalyst prepared in [Example 1] is shown below.

[0046] Figure 2 The X-ray diffraction pattern of the fully crystalline Ti-MWW molecular sieve catalyst prepared in Example 1 is shown below.

[0047] Figure 3 The image shows a scanning electron microscope (SEM) image of the fully crystalline Ti-MWW molecular sieve catalyst prepared in Example 1.

[0048] Figure 4 The image shows the UV-Raman spectrum of the Ti-MWW molecular sieve catalyst prepared in [Comparative Example 1].

[0049] Figure 5 The X-ray diffraction pattern of the Ti-MWW molecular sieve catalyst prepared in [Comparative Example 1] is shown below.

[0050] Figure 6 The image shows a scanning electron microscope (SEM) image of the Ti-MWW molecular sieve catalyst prepared in Comparative Example 1.

[0051] Figure 7 The image shows the UV-Raman spectrum of the Ti-MWW molecular sieve catalyst prepared in [Comparative Example 2].

[0052] Figure 8 The image shows the UV-Raman spectrum of the Ti-MWW molecular sieve catalyst prepared in [Comparative Example 3].

[0053] Figure 9 The image shows the UV-Raman spectrum of the Ti-MWW molecular sieve catalyst prepared in [Comparative Example 4].

[0054] Figure 10 The image shows the UV-Raman spectrum of the Ti-MWW molecular sieve catalyst prepared in [Comparative Example 5]. Detailed Implementation

[0055] The technical solution of the present invention will be further illustrated below with reference to the embodiments, but it is not limited to the following embodiments.

[0056] In this invention, unless otherwise expressly stated, percentages and whole parts are by mass. Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprising of," etc., shall be understood to include the stated steps or components, but not to exclude other steps or other components.

[0057] In this invention, including the following examples and comparative examples, the state, structure, and morphology of the titanium species in the molecular sieve catalyst were determined by ultraviolet Raman spectroscopy, X-ray diffraction, and scanning electron microscopy, respectively. The molar ratios of silicon to titanium, boron to silicon, and aluminum to silicon in the molecular sieve catalyst were determined by inductively coupled atomic emission spectrometry. The micropore volume, mesopore volume, and macropore volume of the molecular sieve catalyst were determined by nitrogen adsorption-desorption and mercury porosimetry, respectively. The proportion of micropore volume to total pore volume is calculated by dividing the micropore volume by the sum of the micropore volume and the mesopore and macropore volumes. The mechanical strength of the molecular sieve catalyst was determined by a strength tester.

[0058] In this invention, the ultraviolet Raman spectroscopy testing method is as follows: A domestically produced UV Raman-100 ultraviolet Raman spectrometer is used for testing, with an excitation wavelength of 244 nm, a laser power of 5.0 mW illuminating the sample, and a spectral resolution of 4 cm⁻¹. -1 The intensity of a spectral peak is obtained by subtracting the baseline background from the peak value.

[0059] In this invention, the X-ray diffraction testing method is as follows: the phase composition of the sample is analyzed using a Rigaku UlTima IV X-ray powder diffractometer from Japan, with Cu Kα lines as the X-ray source. Nickel filter, 2θ scanning range 2-50°, operating voltage 40kV, current 40mA, scanning rate 10° / min.

[0060] In this invention, the scanning electron microscope testing method is as follows: the Hitachi S-4800 electron microscope is used for testing, and the accelerating voltage is 3kV.

[0061] In this invention, the inductively coupled atomic emission spectroscopy (ICAES) method is as follows: the silicon-titanium molar ratio, boron-silicon molar ratio, and aluminum-silicon molar ratio in the sample are analyzed using a Varian-2000 analyzer. Before the test, the sample is dissolved in hydrofluoric acid solution.

[0062] In this invention, the nitrogen adsorption-desorption test method is as follows: the nitrogen adsorption-desorption isotherm of the sample is measured using a Micron ASAP2460 instrument (USA), and the micropore volume is determined accordingly. The measurement temperature is 77K. Before the test, the sample is pretreated in a vacuum at 573K for 6 hours. The mercury porosimetry test method is as follows: the test is performed using a high-performance fully automated mercury porosimetry instrument, AutoPore IV 9505.

[0063] In this invention, the mechanical strength testing method is as follows: the DL-2 type particle strength tester is used to test the size of the catalyst in the direction of force application, and then the external force required to compress the catalyst into powder is measured. The mechanical strength of the catalyst is obtained by dividing the external force by the size.

[0064] In this invention, the reaction liquid after flowing through the catalyst bed is collected, and the concentration of hydrogen peroxide in the reaction liquid is determined by cerium sulfate titration. The residual hydrogen peroxide rate and the hydrogen peroxide conversion rate are then calculated.

[0065]

[0066] Hydrogen peroxide conversion rate % = 1 - hydrogen peroxide residue rate %.

[0067] In this invention, gas chromatography is used to analyze the product composition and calculate the selectivity of the main product epoxide and the byproducts diol and alcohol ether, as well as the ratio of main to byproducts.

[0068]

[0069]

[0070] In this invention, timing begins when the two plunger pumps are turned on and ends when the residual hydrogen peroxide in the reaction solution reaches 2%. The corresponding running time is the catalyst stabilization time.

[0071]

Example 1

[0072] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0073] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0074] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0075] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S1.

[0076] The UV-Raman spectrum of catalyst S1 is as follows: Figure 1 As shown, 343, 484, 699, and 1097 cm were observed. -1 Spectrum peak, 699cm -1 The peak intensity is 343 cm⁻¹ -1 5.3 times the peak intensity, 1097 cm⁻¹ -1 The peak intensity is 343 cm⁻¹ -1 The spectral peak intensity is 5.1 times that of the peak intensities. Among them, 343 cm⁻¹ -1 The spectral peaks belong to the MWW structure, at 484 and 1097 cm⁻¹. -1 The spectral peak belongs to a four-coordinate titanium species with a skeletal framework, 699 cm⁻¹ -1 The spectral peaks belong to non-framework six-coordinate titanium species, with high strengths of 699 and 1097 cm⁻¹. -1 The presence of spectral peaks indicates the presence of a large number of well-preserved titanium species.

[0077] The X-ray diffraction pattern of catalyst S1 is as follows: Figure 2As shown, strong diffraction peaks appear at 2θ of 3.3°, 6.6°, 7.2°, 7.9°, 9.7°, and 26.1°, indicating that S1 has an MWW structure and high crystallinity. The scanning electron microscope image of the catalyst S1 is shown below. Figure 3 As shown, the sample exhibits a layered morphology, and no nanoparticles were observed, indicating that S1 is a pure-phase single MWW structure.

[0078] The catalyst S1 has a silicon-to-titanium molar ratio of 35 and a boron-to-silicon molar ratio of 0.015.

[0079] The catalyst S1 has a micropore volume of 0.09 cm³. 3 / g, the proportion of micropore volume to total pore volume is 3.6%, and the mechanical strength is 66N / cm.

[0080]

Example 2

[0081] (1) 90g of Ti-MWW molecular sieve powder with a silicon-titanium molar ratio of 5, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of starch and 0.9g of potassium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0082] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0083] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0084] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S2.

[0085] The UV-Raman spectra of catalyst S2 showed values ​​of 341, 487, 702, and 1094 cm⁻¹. -1 Spectral peak, 702cm -1 The peak intensity is 341 cm⁻¹ -1Ten times the intensity of the spectral peak, 1094 cm⁻¹ -1 The peak intensity is 341 cm⁻¹ -1 The spectral peak intensity is 10 times that of S2, indicating that S2 has a much greater number of framework tetracoordinated titanium species and non-framework hexacoordinated titanium species than S1.

[0086] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S2 are respectively compared with... Figure 2 , Figure 3 similar.

[0087] The catalyst S2 has a silicon-to-titanium molar ratio of 10 and a boron-to-silicon molar ratio of 0.005.

[0088] The catalyst S2 has a micropore volume of 0.05 cm³. 3 / g, the micropore volume accounts for 1.7% of the total pore volume, and the mechanical strength is 40N / cm.

[0089]

Example 3

[0090] (1) 90g of Ti-MWW molecular sieve powder with a silicon-titanium molar ratio of 120, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 9g of cellulose and 36g of ammonium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0091] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0092] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0093] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S3.

[0094] The UV-Raman spectra of catalyst S3 showed values ​​of 345, 482, 696, and 1099 cm⁻¹. -1 Spectral peak, 696cm-1 The peak intensity is 345 cm⁻¹ -1 0.5 times the peak intensity, 1099 cm⁻¹ -1 The peak intensity is 345 cm⁻¹ -1 The peak intensity is 0.5 times that of S3, indicating that S3 has far fewer framework tetracoordinate titanium species and non-framework hexacoordinate titanium species than S1.

[0095] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S3 are respectively compared with... Figure 2 , Figure 3 similar.

[0096] The catalyst S3 has a silicon-to-titanium molar ratio of 200 and a boron-to-silicon molar ratio of 0.03.

[0097] The catalyst S3 has a micropore volume of 0.07 cm³. 3 / g, the proportion of micropore volume to total pore volume is 2.3%, and the mechanical strength is 80N / cm.

[0098]

Example 4

[0099] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 9g of amorphous binder (the amorphous binder includes 8g of silica sol with a mass fraction of 25% and 1g of sodium tetraborate), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 120g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 450℃ for 12 hours to obtain a cylindrical molded product.

[0100] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0101] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0102] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S4.

[0103] The UV-Raman spectra of catalyst S4 showed values ​​of 347, 480, 695, and 1101 cm⁻¹. -1 Spectral peak, 695cm -1 The peak intensity is 347 cm⁻¹ -1 8.2 times the peak intensity, 1101 cm⁻¹ -1 The peak intensity is 347 cm⁻¹ -1 7.8 times the intensity of the spectral peak.

[0104] The X-ray diffraction pattern and scanning electron microscope image of catalyst S4 are respectively compared with... Figure 2 , Figure 3 similar.

[0105] The catalyst S4 has a silicon-to-titanium molar ratio of 25 and a boron-to-silicon molar ratio of 0.003.

[0106] The catalyst S4 has a micropore volume of 0.06 cm³. 3 / g, the proportion of micropore volume to total pore volume is 2%, and the mechanical strength is 30N / cm.

[0107]

Example 5

[0108] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 30g of silica, 30g of boric acid, and 30g of aluminum hydroxide), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 120g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 650℃ for 4 hours to obtain a cylindrical molded product.

[0109] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0110] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0111] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S5.

[0112] The UV-Raman spectra of catalyst S5 showed values ​​of 341, 486, 701, and 1095 cm⁻¹. -1 Spectral peak, 701 cm⁻¹ -1 The peak intensity is 341 cm⁻¹ -1 2.9 times the peak intensity, 1095 cm⁻¹ -1 The peak intensity is 341 cm⁻¹ -1 The peak intensity is 2.6 times that of S1. Compared to S1, the spectral peaks of the four-coordinated titanium species in the S5 framework are located at 486 and 1095 cm⁻¹. -1 At this location, the spectral peak of the non-framework six-coordinate titanium species of S5 is located at 701 cm⁻¹. -1 The presence of this information indicates that the titanium species in S5 are not as good as those in S1.

[0113] The X-ray diffraction pattern and scanning electron microscope image of catalyst S5 are respectively compared with... Figure 2 , Figure 3 similar.

[0114] The catalyst S5 has a silicon-to-titanium molar ratio of 60, a boron-to-silicon molar ratio of 0.1, and an aluminum-to-silicon molar ratio of 0.1.

[0115] The catalyst S5 has a micropore volume of 0.1 cm³. 3 / g, the micropore volume accounts for 4% of the total pore volume, and the mechanical strength is 77N / cm.

[0116]

Example 6

[0117] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of aluminum hydroxide), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0118] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0119] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0120] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S6.

[0121] The UV-Raman spectra of catalyst S6 showed values ​​of 339, 488, 703, and 1093 cm⁻¹. -1 Spectral peak, 703 cm⁻¹ -1 The peak intensity is 339 cm⁻¹ -1 4.9 times the peak intensity, 1093 cm⁻¹ -1 The peak intensity is 339 cm⁻¹ -1 The peak intensity is 5.2 times that of S1. Compared to S1, the spectral peaks of the four-coordinated titanium species in the S6 framework are located at 488 and 1093 cm⁻¹. -1 At this location, the spectral peak of the non-framework six-coordinate titanium species of S6 is located at 703 cm⁻¹. -1 The presence of this information indicates that the titanium species in S6 are not as good as those in S1.

[0122] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S6 are respectively compared with... Figure 2 , Figure 3 similar.

[0123] The catalyst S6 has a silicon-to-titanium molar ratio of 37 and an aluminum-to-silicon molar ratio of 0.05.

[0124] The catalyst S6 has a micropore volume of 0.12 cm³. 3 / g, the proportion of micropore volume to total pore volume is 6%, and the mechanical strength is 90N / cm.

[0125]

Example 7

[0126] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then, 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After being spherical and granulated, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a spherical molded product.

[0127] (2) Place 90 grams of the spherical material described in step (1) above 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, spherical catalyst precursor A is obtained.

[0128] (3) Mix 60g of the spherical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain spherical catalyst precursor B.

[0129] (4) Mix 40g of the spherical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S7.

[0130] The UV-Raman spectra of catalyst S7 showed values ​​of 343, 484, 699, and 1097 cm⁻¹. -1 Spectrum peak, 699cm -1 The peak intensity is 343 cm⁻¹ -1 5.3 times the peak intensity, 1097 cm⁻¹ -1 The peak intensity is 343 cm⁻¹ -1 The peak intensity is 5.2 times that of the spectral peak.

[0131] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S7 are respectively compared with... Figure 2 , Figure 3 similar.

[0132] The catalyst S7 has a silicon-to-titanium molar ratio of 34 and a boron-to-silicon molar ratio of 0.014.

[0133] The catalyst S7 has a micropore volume of 0.09 cm³. 3 / g, the proportion of micropore volume to total pore volume is 3.6%, and the mechanical strength is 80N / cm.

[0134]

Example 8

[0135] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0136] (2) Place 90g of the cylindrical molded material described in step (1) on top of 900g of piperidine solution with a concentration of 0.3mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0137] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0138] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S8.

[0139] The UV-Raman spectra of catalyst S8 showed values ​​of 341, 486, 701, and 1095 cm⁻¹. -1 Spectral peak, 701 cm⁻¹ -1 The peak intensity is 341 cm⁻¹ -1 4.8 times the peak intensity, 1095 cm⁻¹ -1 The peak intensity is 341 cm⁻¹ -1 The spectral peak intensity is 5.9 times that of the peak.

[0140] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S8 are respectively compared with... Figure 2 , Figure 3 similar.

[0141] The catalyst S8 has a silicon-to-titanium molar ratio of 32 and a boron-to-silicon molar ratio of 0.017.

[0142] The catalyst S8 has a micropore volume of 0.07 cm³. 3 / g, the proportion of micropore volume to total pore volume is 2.3%, and the mechanical strength is 56N / cm.

[0143]

Example 9

[0144] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0145] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 9 grams of piperidine solution with a concentration of 15 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0146] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0147] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S9.

[0148] The UV-Raman spectra of catalyst S9 showed values ​​of 345, 483, 698, and 1099 cm⁻¹. -1 Spectral peak, 698cm -1 The peak intensity is 345 cm⁻¹ -1 5.7 times the peak intensity, 1099 cm⁻¹ -1 The peak intensity is 345 cm⁻¹ -1 The spectral peak intensity is 4.9 times that of the peak.

[0149] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S9 are respectively compared with... Figure 2 , Figure 3 similar.

[0150] The catalyst S9 has a silicon-to-titanium molar ratio of 34 and a boron-to-silicon molar ratio of 0.016.

[0151] The catalyst S9 has a micropore volume of 0.08 cm³. 3 / g, the micropore volume accounts for 3.2% of the total pore volume, and the mechanical strength is 64 N / cm.

[0152]

Example 10

[0153] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0154] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of hexamethyleneimine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 130°C for 9 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0155] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0156] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S10.

[0157] The UV-Raman spectra of the catalyst S10 showed values ​​of 341, 486, 701, and 1095 cm⁻¹. -1 Spectral peak, 701 cm⁻¹ -1 The peak intensity is 341 cm⁻¹ -1 4.5 times the intensity of the spectral peak, 1095 cm⁻¹ -1 The peak intensity is 341 cm⁻¹ -1 The spectral peak intensity is 4.9 times that of the peak.

[0158] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S10 are respectively compared with... Figure 2 , Figure 3 similar.

[0159] The catalyst S10 has a silicon-to-titanium molar ratio of 42 and a boron-to-silicon molar ratio of 0.02.

[0160] The catalyst S10 has a micropore volume of 0.06 cm³. 3 / g, the micropore volume accounts for 2% of the total pore volume, and the mechanical strength is 45N / cm.

[0161]

Example 11

[0162] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0163] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of hexamethyleneimine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 190°C for 1 day in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0164] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0165] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S11.

[0166] The UV-Raman spectra of the catalyst S11 showed values ​​of 345, 482, 698, and 1099 cm⁻¹. -1 Spectral peak, 698cm -1 The peak intensity is 345 cm⁻¹ -1 Six times the intensity of the spectral peak, 1099 cm⁻¹ -1 The peak intensity is 345 cm⁻¹ -1 Five times the intensity of the spectral peak.

[0167] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S11 are respectively compared with... Figure 2 , Figure 3 similar.

[0168] The catalyst S11 has a silicon-to-titanium molar ratio of 30 and a boron-to-silicon molar ratio of 0.01.

[0169] The catalyst S11 has a micropore volume of 0.07 cm³. 3 / g, the proportion of micropore volume to total pore volume is 2.3%, and the mechanical strength is 69 N / cm.

[0170]

Example 12

[0171] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0172] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0173] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 12mol / L hydrochloric acid solution at a solid-liquid mass ratio of 1:10, treat at 130℃ for 4 hours, wash, dry at 100℃ for 8 hours and calcine at 450℃ for 12 hours to obtain cylindrical catalyst precursor B.

[0174] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S12.

[0175] The UV-Raman spectrum of catalyst S12 showed values ​​of 344, 481, 698, and 1100 cm⁻¹. -1 Spectral peak, 698cm -1 The peak intensity is 344 cm⁻¹ -1 3.3 times the peak intensity, 1100 cm⁻¹ -1 The peak intensity is 344 cm⁻¹ -1 The peak intensity is 2.4 times that of the spectral peak.

[0176] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S12 are respectively compared with... Figure 2 , Figure 3 similar.

[0177] The catalyst S12 has a silicon-to-titanium molar ratio of 57 and a boron-to-silicon molar ratio of 0.004.

[0178] The catalyst S12 has a micropore volume of 0.1 cm³. 3 / g, the micropore volume accounts for 4% of the total pore volume, and the mechanical strength is 48N / cm.

[0179]

Example 13

[0180] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0181] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0182] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 0.3mol / L oxalic acid solution at a solid-liquid mass ratio of 1:80, treat at 60℃ for 48 hours, wash, dry at 100℃ for 8 hours and calcine at 650℃ for 4 hours to obtain cylindrical catalyst precursor B.

[0183] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S13.

[0184] The UV-Raman spectra of catalyst S13 showed values ​​of 341, 488, 702, and 1093 cm⁻¹. -1 Spectral peak, 702cm -1 The peak intensity is 341 cm⁻¹ -1 The spectral peak intensity is 5.9 times that of 1093 cm⁻¹. -1 The peak intensity is 341 cm⁻¹ -1 The spectral peak intensity is 5.7 times that of the peak.

[0185] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S13 are respectively compared with... Figure 2 , Figure 3 similar.

[0186] The catalyst S13 has a silicon-to-titanium molar ratio of 27 and a boron-to-silicon molar ratio of 0.08.

[0187] The catalyst S13 has a micropore volume of 0.05 cm³. 3 / g, the proportion of micropore volume to total pore volume is 1.7%, and the mechanical strength is 60N / cm.

[0188]

Example 14

[0189] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0190] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0191] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0192] (4) 40 grams of the cylindrical catalyst precursor B described in step (3) are mixed with ammonium fluoride and 3 mol / L hexamethyleneimine solution at a mass ratio of 1:0.2:20, treated at 170°C for 48 hours, washed and dried at 100°C for 8 hours to obtain a fully crystalline Ti-MWW molecular sieve catalyst, denoted as S14.

[0193] The UV-Raman spectra of catalyst S14 showed values ​​of 342, 484, 700, and 1097 cm⁻¹. -1 Spectral peak, 700cm -1 The peak intensity is 342 cm⁻¹ -1 Five times the intensity of the spectral peak, 1097 cm⁻¹ -1 The peak intensity is 342 cm⁻¹ -1 The spectral peak intensity is 4.8 times that of the peak intensity.

[0194] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S14 are respectively compared with... Figure 2 , Figure 3 similar.

[0195] The catalyst S14 has a silicon-to-titanium molar ratio of 39 and a boron-to-silicon molar ratio of 0.018.

[0196] The catalyst S14 has a micropore volume of 0.08 cm³. 3 / g, the micropore volume accounts for 3.2% of the total pore volume, and the mechanical strength is 62N / cm.

[0197]

Example 15

[0198] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0199] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0200] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0201] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with potassium fluoride and 15mol / L piperidine solution at a mass ratio of 1:0.4:2, treat at 190℃ for 4 hours, wash and dry at 100℃ for 8 hours to obtain the fully crystalline Ti-MWW molecular sieve catalyst, denoted as S15.

[0202] The UV-Raman spectra of catalyst S15 showed values ​​of 342, 485, 701, and 1095 cm⁻¹. -1 Spectral peak, 701 cm⁻¹ -1 The peak intensity is 342 cm⁻¹ -1 The spectral peak intensity is 6.8 times that of 1095 cm⁻¹. -1 The peak intensity is 342 cm⁻¹ -1 3.2 times the intensity of the spectral peak.

[0203] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S15 are respectively compared with... Figure 2 , Figure 3 similar.

[0204] The catalyst S15 has a silicon-to-titanium molar ratio of 37 and a boron-to-silicon molar ratio of 0.025.

[0205] The catalyst S15 has a micropore volume of 0.15 cm³. 3 / g, the micropore volume accounts for 7.5% of the total pore volume, and the mechanical strength is 64 N / cm.

[0206]

Example 16

[0207] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0208] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0209] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0210] (4) 40 grams of the cylindrical catalyst precursor B described in step (3) were mixed with sodium fluoride and 0.3 mol / L piperidine solution at a mass ratio of 1:0.05:20 and treated at 130°C for 48 hours. After washing and drying at 100°C for 8 hours, a fully crystalline Ti-MWW molecular sieve catalyst was obtained, denoted as S16.

[0211] The UV-Raman spectra of catalyst S16 showed values ​​of 344, 482, 698, and 1098 cm⁻¹. -1 Spectral peak, 698cm -1 The peak intensity is 344 cm⁻¹ -1 3.3 times the peak intensity, 1098 cm⁻¹ -1 The peak intensity is 344 cm⁻¹ -1 The spectral peak intensity is 6.9 times that of the peak.

[0212] The X-ray diffraction pattern and scanning electron microscope image of the catalyst S16 are respectively compared with... Figure 2 , Figure 3 similar.

[0213] The catalyst S16 has a silicon-to-titanium molar ratio of 36 and a boron-to-silicon molar ratio of 0.01.

[0214] The catalyst S16 has a micropore volume of 0.03 cm³. 3 / g, the micropore volume accounts for 1% of the total pore volume, and the mechanical strength is 57N / cm.

[0215]

Examples 17-24

[0216] The fully crystalline Ti-MWW molecular sieve catalysts prepared in Examples 1, 2, 3, 6, 11, 12, 15, and 16 were subjected to continuous liquid-phase epoxidation of propylene in a stainless steel fixed-bed reactor. Two grams of the fully crystalline Ti-MWW molecular sieve catalyst were crushed into 20-40 mesh particles and filled into a stainless steel reaction tube, with both ends of the tube filled with glass beads. The reaction was carried out under liquid-phase epoxidation conditions at a temperature of 40°C and a pressure of 2.0 MPa, using a bottom-feed, top-discharge configuration. Nitrogen was used to balance the propylene pressure to 2.5 MPa to ensure complete propylene liquefaction. The propylene feedstock was fed separately and denoted as feedstock A. A 30% hydrogen peroxide aqueous solution was prepared, containing 15 ppm piperidine, and mixed with acetonitrile, denoted as feedstock B. Two feed streams were fed separately using plunger pumps. The two feed streams were premixed before flowing through the catalyst bed. In the total feed stream, the mass fraction of propylene was 18.7%, the mass fraction of acetonitrile was 61.0%, the molar ratio of propylene to hydrogen peroxide was 1:0.4, and the flow rate per unit mass of catalyst was 6 mL·g. cat. -1 ·h -1 The reaction liquid after flowing through the catalyst bed was collected, and the results are shown in Table 1.

[0217] Table 1 Catalytic performance of catalysts for propylene epoxidation in each example

[0218]

[0219]

[0220] Note: a. The hydrogen peroxide conversion rate and residual rate are data at the beginning of the reaction;

[0221] b. During continuous reactions, the selectivity of propylene oxide and the ratio of main to byproducts remain stable;

[0222] c. Catalyst stabilization time refers to the running time from the start of the reaction until the hydrogen peroxide conversion rate is less than 98.0% and the residual hydrogen peroxide in the reaction solution reaches 2%.

[0223]

Examples 25-28

[0224] The allocrystalline Ti-MWW molecular sieve catalysts prepared in Examples 1, 6, 11, and 16 were subjected to continuous liquid-phase epoxidation of allyl chloride in a stainless steel fixed-bed reactor. Two grams of the allocrystalline Ti-MWW molecular sieve catalyst were crushed into 20-40 mesh particles and filled into a stainless steel reaction tube, with both ends of the tube filled with glass beads. The reaction was carried out under liquid-phase epoxidation conditions at a temperature of 60°C and a pressure of 0.6 MPa, using a bottom-feed, top-discharge configuration. The allyl chloride feed solution was fed separately and designated as feed solution A. A 30% (w / w) aqueous solution containing 50 ppm hexamethyleneimine was prepared and mixed with acetonitrile, designated as feed solution B. Two feed streams were fed separately using plunger pumps. The two feed streams were premixed before flowing through the catalyst bed. In the total feed stream, the mass fraction of allyl chloride was 27.7%, the mass fraction of acetonitrile was 54.2%, the molar ratio of allyl chloride to hydrogen peroxide was 1:0.4, and the flow rate per unit mass of catalyst was 4 mL·g. cat. -1 ·h -1 The reaction liquid after flowing through the catalyst bed was collected, and the results are shown in Table 2 below:

[0225] Table 2 Catalytic performance of catalysts for the epoxidation of propylene chloride in each example.

[0226]

[0227] Note: a. The hydrogen peroxide conversion rate and residual rate are data at the beginning of the reaction;

[0228] b. During continuous reactions, the selectivity of epichlorohydrin and the ratio of main to byproducts remain stable;

[0229] c. Catalyst stabilization time refers to the running time from the start of the reaction until the hydrogen peroxide conversion rate is less than 98.0% and the residual hydrogen peroxide in the reaction solution reaches 2%.

[0230] Comparative Example 1

[0231] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0232] (2) Mix 60g of the cylindrical molding material described in step (1) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain a cylindrical catalyst precursor.

[0233] (3) Mix 40g of the cylindrical catalyst precursor described in step (2) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain Ti-MWW molecular sieve catalyst, denoted as D1.

[0234] The UV-Raman spectrum of D1 is as follows: Figure 4 As shown, only 491 and 1080 cm were observed. -1 The spectral peaks indicate that the titanium species are in poor condition.

[0235] The X-ray diffraction pattern of D1 is as follows: Figure 5 As shown, diffraction peaks appear at 2θ of 3.3°, 6.6°, 7.2°, 7.9°, 9.7°, and 26.1°, with significantly weaker intensities than S1, indicating that the main body of D1 is still an MWW structure. However, the presence of strong, broad diffraction peaks in the 17.5–30° region suggests the presence of amorphous species in D1. Scanning electron microscopy images are shown below. Figure 6 As shown, in addition to the observed lamellar morphology, nanoparticles were also observed, further indicating the presence of amorphous species in D1.

[0236] The silicon-to-titanium molar ratio of D1 is 30, and the boron-to-silicon molar ratio is 0.06.

[0237] The micropore volume of D1 is 0.04 cm³. 3 / g, the proportion of micropore volume to total pore volume is 1.4%, and the mechanical strength is 29 N / cm.

[0238] Comparative Example 2

[0239] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0240] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, a cylindrical catalyst precursor is obtained.

[0241] (3) Mix 40g of the cylindrical catalyst precursor described in step (2) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain Ti-MWW molecular sieve catalyst, denoted as D2.

[0242] The UV-Raman spectrum of D2 is as follows: Figure 7 As shown, 342, 491, and 1090 cm were observed. -1 Spectral peak, 1090cm -1 The peak intensity is 342 cm⁻¹ -1 The spectral peak intensity is 11.2 times that of the standard peak, indicating the presence of a large number of poorly configured skeletal tetracoordinate titanium species.

[0243] The X-ray diffraction pattern and scanning electron microscope image of D2 are respectively compared with... Figure 2 , Figure 3 similar.

[0244] The silicon-to-titanium molar ratio of D2 is 31, and the boron-to-silicon molar ratio is 0.05.

[0245] The micropore volume of D2 is 0.08 cm³. 3 / g, the proportion of micropore volume to total pore volume is 3.2%, and the mechanical strength is 68 N / cm.

[0246] Comparative Example 3

[0247] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0248] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, a cylindrical catalyst precursor is obtained.

[0249] (3) Mix 60g of the cylindrical catalyst precursor described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain Ti-MWW molecular sieve catalyst, denoted as D3.

[0250] The UV-Raman spectrum of D3 is as follows: Figure 8 As shown, 343, 490, and 1092 cm were observed. -1 Spectral peak, 1092 cm⁻¹ -1 The peak intensity is 343 cm⁻¹ -1 The spectral peak intensity is 10.2 times that of the standard peak, indicating the presence of a large number of poorly configured four-coordinated titanium species.

[0251] The X-ray diffraction pattern and scanning electron microscope image of D3 are respectively compared with... Figure 2 , Figure 3 similar.

[0252] The silicon-to-titanium molar ratio of D3 is 36, and the boron-to-silicon molar ratio is 0.017.

[0253] The micropore volume of D3 is 0.16 cm³. 3 / g, the proportion of micropore volume to total pore volume is 7.8%, and the mechanical strength is 58 N / cm.

[0254] Comparative Example 4

[0255] (1) 90g of Ti-MWW molecular sieve powder with a silicon-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid) and 3g of guar gum powder are mixed evenly under mechanical stirring. Then, 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0256] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0257] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0258] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with ammonium fluoride and 3mol / L piperidine solution at a mass ratio of 1:0.1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain Ti-MWW molecular sieve catalyst, denoted as D4.

[0259] The UV-Raman spectrum of D4 is as follows: Figure 9As shown, 340, 488, and 1087 cm were observed. -1 Spectral peak, 1087cm -1 The peak intensity is 340 cm⁻¹ -1 The spectral peak intensity is 10.9 times that of the standard peak, indicating the presence of a large number of poorly configured skeletal tetracoordinate titanium species.

[0260] The X-ray diffraction pattern and scanning electron microscope image of D4 are respectively compared with... Figure 5 , Figure 6 similar.

[0261] The silicon-to-titanium molar ratio of D4 is 33, and the boron-to-silicon molar ratio is 0.012.

[0262] The micropore volume of D4 is 0.05 cm³. 3 / g, the proportion of micropore volume to total pore volume is 1.7%, and the mechanical strength is 36N / cm.

[0263] Comparative Example 5

[0264] (1) 90g of Ti-MWW molecular sieve powder with a silicon-to-titanium molar ratio of 20, 90g of amorphous binder (the amorphous binder includes 75g of silica sol with a mass fraction of 40% and 15g of boric acid), 3g of guar gum powder and 9g of sodium fluoride are mixed evenly under mechanical stirring. Then 80g of water is added and the mixture is stirred and kneaded for 4 hours to obtain a solid mixture with a certain viscosity. After mechanical extrusion molding, it is dried at 100℃ for 8 hours and then calcined at 550℃ for 6 hours to obtain a cylindrical molded product.

[0265] (2) Place 90 grams of the cylindrical molded material described in step (1) on top of 60 grams of piperidine solution with a concentration of 3 mol / L, without contact between the two, and crystallize at 170°C for 2 days in a sealed environment. After washing and drying at 100°C for 8 hours, cylindrical catalyst precursor A is obtained.

[0266] (3) Mix 60g of the cylindrical catalyst precursor A described in step (2) with 2mol / L nitric acid solution at a solid-liquid mass ratio of 1:50, treat at 80℃ for 24 hours, wash, dry at 100℃ for 8 hours and calcine at 550℃ for 6 hours to obtain cylindrical catalyst precursor B.

[0267] (4) Mix 40g of the cylindrical catalyst precursor B described in step (3) with a 3mol / L piperidine solution at a mass ratio of 1:10, treat at 170℃ for 24 hours, wash and dry at 100℃ for 8 hours to obtain the Ti-MWW molecular sieve catalyst, denoted as D5.

[0268] The UV-Raman spectrum of D5 is as follows: Figure 10 As shown, 342, 490, and 1102 cm were observed. -1 Spectral peak, 1102 cm⁻¹-1 The peak intensity is 342 cm⁻¹ -1 The spectral peak intensity is 10.3 times that of the standard peak, indicating the presence of a large number of poorly configured four-coordinated titanium species.

[0269] The X-ray diffraction pattern and scanning electron microscope image of D5 are respectively compared with... Figure 2 , Figure 3 similar.

[0270] The silicon-to-titanium molar ratio of D5 is 36, and the boron-to-silicon molar ratio is 0.017.

[0271] The micropore volume of D5 is 0.04 cm³. 3 / g, the proportion of micropore volume to total pore volume is 1.3%, and the mechanical strength is 74 N / cm.

[0272] Comparative Examples 6-10

[0273] The Ti-MWW molecular sieve catalysts D1 to D5 obtained in Comparative Examples 1 to 5 were subjected to continuous liquid-phase epoxidation of propylene under the reaction conditions of Examples 17 to 24, respectively. The reaction results are shown in Table 3 below:

[0274] Table 3 Catalytic performance of each comparative catalyst for propylene epoxidation

[0275]

[0276] Note: a. The hydrogen peroxide conversion rate and residual rate are data at the beginning of the reaction;

[0277] b. During continuous reactions, the selectivity of propylene oxide and the ratio of main to byproducts remain stable;

[0278] c. Catalyst stabilization time refers to the running time from the start of the reaction until the hydrogen peroxide conversion rate is less than 98.0% and the residual hydrogen peroxide in the reaction solution reaches 2%.

[0279] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A fully crystalline Ti-MWW molecular sieve catalyst with a UV-Raman spectrum at 343±4 cm⁻¹ -1 484±4 cm -1 699±4 cm -1 and 1097±4 cm -1 A spectral peak appears at 699±4 cm⁻¹. -1 The intensity of the spectral peak is 343±4 cm. -1 The spectral peak intensity is 0.5 to 10 times that of the peak, 1097 ± 4 cm⁻¹. -1 The intensity of the spectral peak is 343±4 cm. -1 0.5 to 10 times the intensity of the spectral peak; The silicon-to-titanium molar ratio in the molecular sieve catalyst is 10-200; The molecular sieve catalyst further includes at least one element selected from boron and aluminum; the molar ratio of boron to silicon in the molecular sieve catalyst is 0 to 0.1; the molar ratio of aluminum to silicon in the molecular sieve catalyst is 0 to 0.

1. The molecular sieve catalyst has a micropore volume of 0.03~0.15 cm³. 3 / g, the proportion of micropore volume to total pore volume is 1%~7.5%; The mechanical strength of the molecular sieve catalyst is 30~90 N / cm.

2. The molecular sieve catalyst according to claim 1, characterized in that, In the UV-Raman spectrum of the molecular sieve catalyst, 699±4 cm⁻¹ -1 The intensity of the spectral peak is 343±4 cm. -1 The peak intensity is 2 to 10 times that of the spectral peak, 1097 ± 4 cm⁻¹ -1 The intensity of the spectral peak is 343±4 cm. -1 Two to ten times the intensity of the spectral peak.

3. The molecular sieve catalyst according to claim 1, characterized in that, The silicon-to-titanium molar ratio in the molecular sieve catalyst is 25-100.

4. The molecular sieve catalyst according to claim 1, characterized in that, In the molecular sieve catalyst, the boron-silicon molar ratio is 0.005~0.03; in the molecular sieve catalyst, the aluminum-silicon molar ratio is 0~0.

05.

5. The molecular sieve catalyst according to claim 1, characterized in that, The micropore volume of the molecular sieve catalyst is 0.03~0.12 cm³. 3 / g; the proportion of micropore volume to total pore volume is 1~6%.

6. The molecular sieve catalyst according to claim 1, characterized in that, The micropore volume of the molecular sieve catalyst is 0.05~0.10 cm³. 3 / g; the proportion of micropore volume to total pore volume is 1.7%~5%.

7. The molecular sieve catalyst according to claim 1, characterized in that, The mechanical strength of the molecular sieve catalyst is 40~80 N / cm.

8. A method for preparing a fully crystalline Ti-MWW molecular sieve catalyst, comprising the following steps: (1) Ti-MWW molecular sieve powder, binder, pore-forming agent and fluoride are kneaded into a molded shape and calcined to obtain the molded product; (2) The shaped material from step (1) is crystallized in an environment containing an organic amine solution to obtain catalyst precursor A; (3) The catalyst precursor A from step (2) is subjected to acid solution treatment and calcined to obtain catalyst precursor B; (4) The catalyst precursor B from step (3) is treated with an organic amine solution to obtain the molecular sieve catalyst; The binder mentioned in step (1) includes a silicon source and at least one selected from boron source and aluminum source; in the binder composition, the molar ratio of SiO2:B2O3:Al2O3 is 1:x:y, based on oxides, where x=0~0.5, y=0~0.5, and x+y=0.02~1; The crystallization process in step (2) in the presence of an organic amine solution includes: in step (1), the molded material is placed above the organic amine solution for crystallization, and the molded material does not come into contact with the organic amine solution; the crystallization conditions are: crystallization temperature of 130~190 ℃ and crystallization time of 1~9 days; The acid solution treatment process in step (3) includes: step (2) catalyst precursor A reacting with acid solution; the acid solution is selected from at least one of nitric acid and hydrochloric acid solutions; the concentration of the acid solution is 0.3~12 mol / L; the solid-liquid mass ratio of catalyst precursor A to acid solution is 1:10~80; the acid solution treatment conditions are: treatment temperature of 60~130 ℃, treatment time of 4~48 hours; The organic amine solution treatment process in step (4) includes: step (3) catalyst precursor B reacting with fluoride and organic amine solution; the fluoride is selected from at least one of sodium fluoride, potassium fluoride and ammonium fluoride; the organic amine is selected from at least one of piperidine and hexamethyleneimine; the concentration of the organic amine solution is 0.3~15 mol / L; the mass ratio of catalyst precursor B, fluoride and organic amine solution is 1:0.05~0.4:2~20; the conditions for organic amine solution treatment are: treatment temperature of 130~190 ℃ and treatment time of 4~48 hours.

9. The preparation method according to claim 8, characterized in that, The silicon source is selected from at least one of silica sol, water glass, silica, and tetraethyl orthosilicate; the boron source is selected from at least one of boric acid, boron trioxide, and borate; and the aluminum source is selected from at least one of aluminum trioxide, aluminum hydroxide, sodium aluminate, aluminum nitrate, and aluminum sulfate.

10. The preparation method according to claim 8 or 9, characterized in that, The pore-forming agent mentioned in step (1) is selected from at least one of guar gum powder, cellulose, chitosan, lignin, starch, polyethylene glycol, triblock copolymer P123 and F127; the fluoride mentioned in step (1) is selected from at least one of sodium fluoride, potassium fluoride and ammonium fluoride; the mass ratio of the raw materials in step (1), Ti-MWW molecular sieve powder, binder, pore-forming agent and fluoride is 1:0.1~1.5:0.01~0.1:0.01~0.

4.

11. The preparation method according to claim 8, characterized in that, In step (2), the organic amine is at least one selected from piperidine and hexamethyleneimine; the concentration of the organic amine solution is 0.3~15 mol / L; and the mass ratio of the molded product to the organic amine solution is 0.1~10:

1.

12. The preparation method according to claim 8, characterized in that, The roasting conditions described in step (1) are 450~650 ℃ in an oxygen-containing atmosphere for 4~12 hours; the roasting conditions described in step (3) are 450~650 ℃ in an oxygen-containing atmosphere for 4~12 hours.

13. The molecular sieve catalyst prepared by any one of claims 8 to 12.

14. The use of the molecular sieve catalyst according to any one of claims 1 to 7 or the molecular sieve catalyst according to claim 13 in the olefin epoxidation reaction.

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