Shaped titanium silicalite molecular sieve, its shaping method and use
By preparing spherical titanium-silicon molecular sieves using freeze-drying technology, the problem of balancing mechanical strength and catalytic activity in the propylene gas-phase epoxidation process was solved, achieving both high catalytic performance and anti-breakage properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-11-27
- Publication Date
- 2026-05-29
AI Technical Summary
Existing catalysts are difficult to balance mechanical strength and catalytic activity in the propylene gas-phase epoxidation process, and powder form can easily cause equipment damage and increased pressure drop.
Spherical titanium-silicon molecular sieves were prepared using a specific freeze-drying technique. A suspension was formed by mixing a pore-forming agent, an auxiliary agent, and silica sol, which was then dropped into liquid nitrogen and frozen into small spheres. After drying and calcination, a catalyst with high resistance to breakage and high catalytic activity was obtained.
The prepared shaped titanium-silicon molecular sieves exhibited excellent anti-breakage strength and catalytic activity in the gas-phase epoxidation reaction of propylene, with a propylene conversion rate of over 3% and a propylene oxide selectivity of over 78%.
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Abstract
Description
Technical Field
[0001] This invention relates to the fields of inorganic chemistry and catalytic chemistry, specifically to a shaped titanium-silicon molecular sieve, its shaping method, and its applications. Background Technology
[0002] TS-1 molecular sieve is a molecular sieve material with titanium atom-inserted framework and MFI topology. In the selective oxidation of hydrocarbons using hydrogen peroxide as an oxidant, TS-1 molecular sieve exhibits unparalleled advantages over conventional methods, such as mild reaction conditions, high atom utilization, and environmentally friendly, pollution-free processes. Currently, Ti-containing heteroatom molecular sieves, represented by TS-1, have been successfully applied in industrial production processes such as propylene epoxidation and cyclohexanone ammonium oximeation.
[0003] The propylene gas-phase epoxidation process for producing propylene oxide directly uses hydrogen, oxygen, and propylene as raw materials. First, hydrogen peroxide is generated in situ, and then propylene is oxidized to produce propylene oxide. Propylene gas-phase epoxidation is a gas-solid heterogeneous reaction, where a solid catalyst is placed in a gas atmosphere with a certain space velocity, typically using a fixed-bed tubular reactor. Given the reaction environment, if the catalyst exists in powder form, it is prone to dust generation, which can easily spread to pipelines connected to the reactor and downstream equipment, causing equipment damage and operational failures. Furthermore, it can lead to a significant pressure drop in the catalyst bed, increasing the risk of production disruptions. Therefore, the catalyst used in the propylene gas-phase epoxidation process must be shaped and possess certain resistance to breakage and abrasion.
[0004] Currently, the commonly used catalyst forming methods are spraying, extrusion, and ball forming. Among them, spraying produces micron-sized fine particles, but still suffers from the aforementioned drawbacks. Both extrusion and ball forming require the addition of various binders, additives, and pore-forming agents to improve catalyst strength, but excessive additives dilute the effective catalyst components, causing varying degrees of decrease in catalytic effect. Summary of the Invention
[0005] The purpose of this invention is to overcome the problem that existing catalysts used in propylene gas-phase epoxidation processes cannot simultaneously achieve both mechanical strength and catalytic activity. This invention provides a shaped titanium-silicon molecular sieve, its shaping method, and its application. This method uses a specific freeze-drying technique to prepare spherical shaped titanium-silicon molecular sieves with high propylene epoxidation reactivity.
[0006] To achieve the above objectives, the first aspect of the present invention provides a method for forming titanium-silicon molecular sieves, the method comprising the following steps:
[0007] (1) A pore-forming agent and silica sol are mixed to form a mixture, and then a mixture of titanium silica molecular sieve and additive powder is mixed with the mixture to obtain a suspension;
[0008] (2) The suspension obtained in step (1) is dropped into liquid nitrogen to obtain solid spheres, and then the solid spheres are dried and calcined to obtain shaped titanium silicon molecular sieves.
[0009] Preferably, in step (1), the pore-forming agent is selected from at least one of surfactants such as octadecylamine salt, sodium oleate of hydroxyethyl sulfonate, and lauryl amide.
[0010] Preferably, in step (1), the SiO2 content in the silica sol is 5-50 wt%.
[0011] Preferably, in step (1), the additive is selected from at least one of tianqing powder, starch and citric acid.
[0012] Preferably, in step (1), the weight ratio of the pore-forming agent, the auxiliary agent, the silica sol (calculated as SiO2), and the titanium-silicon molecular sieve is 0.1-2:0.1-2:1-20:100.
[0013] Preferably, in step (2), the suspension is dripped into the liquid nitrogen through a dropper with a diameter of 0.5-3 mm.
[0014] Preferably, in step (2), the drying method is freeze drying, and the freeze drying conditions include: time of 5-30h and vacuum degree <10Pa.
[0015] Preferably, in step (2), the calcination conditions include: a temperature of 300-800℃ and a time of 1-10h.
[0016] A second aspect of the present invention provides a shaped titanium-silicon molecular sieve prepared by the method described above.
[0017] Preferably, the particle size of the shaped titanium-silicon molecular sieve is 0.5-4 mm, and the crushing strength is 20-100 N / cm.
[0018] A third aspect of the present invention provides an application of the aforementioned shaped titanium-silicon molecular sieve in the catalytic gas-phase epoxidation reaction of propylene.
[0019] The titanium-silicon molecular sieve forming method of the present invention uses a specific freeze-drying technology to fix pore-forming agents, additives and silica sol in titanium-silicon molecular sieve spheres. The spherical titanium-silicon molecular sieve can take into account both mechanical properties and catalytic activity. Its fracture resistance is 20-100 N / cm. When the spherical titanium-silicon molecular sieve is applied to the catalytic gas-phase epoxidation reaction of propylene, the propylene conversion rate is >3% and the propylene oxide selectivity is >78%. Detailed Implementation
[0020] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.
[0021] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0022] The method for forming the titanium-silicon molecular sieve of the present invention includes the following steps:
[0023] (1) A pore-forming agent and silica sol are mixed to form a mixture, and then a mixture of titanium silica molecular sieve and additive powder is mixed with the mixture to obtain a suspension;
[0024] (2) The suspension obtained in step (1) is dropped into liquid nitrogen to obtain solid spheres, and then the solid spheres are dried and calcined to obtain shaped titanium silicon molecular sieves.
[0025] In this invention, in step (1), the pore-forming agent can be at least one of surfactants such as octadecylamine salt, sodium oleate of hydroxyethyl sulfonate, and lauryl amide, with lauryl amide being the most preferred nonionic surfactant. In this invention, when the pore-forming agent is of the above-mentioned type (especially the preferred type), the shaped titanium-silicon molecular sieve prepared from the pore-forming agent has a better pore structure.
[0026] In the method described in this invention, in step (1), the SiO2 content in the silica sol can be 5-50 wt%, preferably 10-30 wt%, and most preferably 20 wt%. In this invention, when the SiO2 content in the silica sol is within the above range (especially the preferred range), the shaped titanium-silicon molecular sieve has higher resistance to breakage and lower coverage of active sites.
[0027] In this invention, in step (1), the additive can be at least one of tianqing powder, starch, and citric acid, with tianqing powder being the most preferred. In this invention, when the additive uses the above-mentioned types (especially the preferred types), the processing performance of the shaped titanium-silicon molecular sieve during the preparation process can be improved.
[0028] In the method described in this invention, in step (1), the weight ratio of the porogen, the additive, the silica sol (based on SiO2), and the titanium-silicon molecular sieve can be 0.1-2:0.1-2:1-20:100, preferably 0.1-1:0.1-1:5-20:100, and most preferably 0.5-1:0.5-1:5-10:100. In the method described in this invention, when the weight ratio of the porogen, the additive, the silica sol (based on SiO2), and the titanium-silicon molecular sieve is within the above range (especially the preferred range), the prepared shaped titanium-silicon molecular sieve has a good pore structure and resistance to breakage, while retaining the catalytic activity of the titanium-silicon molecular sieve.
[0029] In some embodiments, the process of preparing the suspension can be as follows: diluting silica sol with water to 5-50 wt%, then adding a pore-forming agent to the silica sol solution to form a uniform mixture as a binder; mixing titanium silica molecular sieve powder and auxiliary agent powder uniformly to obtain a mixed powder; adding the binder and water to the mixed powder and stirring uniformly to obtain a uniform and flowing suspension, wherein the weight ratio of the pore-forming agent, the auxiliary agent, the silica sol (calculated as SiO2), and the titanium silica molecular sieve can be 0.1-2:0.1-2:1-20:100. When implementing step (1) according to this embodiment, the shaped titanium silica molecular sieve prepared from the suspension has a better pore structure and stronger resistance to breakage.
[0030] In the method described in this invention, in step (2), the suspension is dripped into the liquid nitrogen through a dropper. The diameter of the dropper can be 0.5-3 mm, preferably 0.5-2 mm, and most preferably 1 mm. In this invention, when the diameter of the dropper is within the above range (especially the preferred range), the prepared shaped titanium-silicon molecular sieve has better catalytic activity.
[0031] In the method described in this invention, in step (2), the drying method can be freeze-drying, and the freeze-drying conditions can include: a time of 5-30 hours and a vacuum degree <10 Pa. In this invention, the vacuum degree refers to absolute pressure. In the method described in this invention, when the freeze-drying conditions are within the above range (especially the preferred range), the prepared shaped titanium-silicon molecular sieve has better catalytic activity.
[0032] In the method described in this invention, the calcination conditions in step (2) may include: a temperature of 300-800℃, preferably 400-600℃, and a time of 1-10h, preferably 2-6h. In this invention, when the calcination conditions are within the above range (especially the preferred range), the prepared shaped titanium-silicon molecular sieve exhibits better catalytic activity.
[0033] In some embodiments, the process of preparing the shaped titanium-silicon molecular sieve can be as follows: using a dropper with a diameter of 0.5-3 mm, the suspension is dripped dropwise into liquid nitrogen and frozen into solid microspheres. The microspheres are then transferred to a freeze dryer for drying to obtain dried solid microspheres. The vacuum degree of the freeze drying is <10 Pa, and the time is 5-30 h. The dried solid microspheres are then calcined at 300-800℃ for 1-10 h to obtain the shaped titanium-silicon molecular sieve of the present invention. When step (2) is performed according to this embodiment, the prepared shaped titanium-silicon molecular sieve has a good pore structure and resistance to breakage, while retaining the catalytic activity of the titanium-silicon molecular sieve.
[0034] The shaped titanium-silicon molecular sieve prepared by the method described in this invention has a particle size of 0.5-4 mm, preferably 1-3 mm; and a breakage strength of 20-100 N / cm, preferably 30-60 N / cm. The shaped titanium-silicon molecular sieve method of this invention uses a specific freeze-drying technique to fix pore-forming agents, additives, and silica sol within titanium-silicon molecular sieve spheres. The spherical shaped titanium-silicon molecular sieve can balance mechanical properties and catalytic activity. When the shaped titanium-silicon molecular sieve is applied to the catalytic gas-phase epoxidation reaction of propylene, the propylene conversion rate is >3%, and the propylene oxide selectivity is >78%.
[0035] The following examples further illustrate the molded titanium-silicon molecular sieve, its molding method, and its application according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.
[0036] Unless otherwise specified, the experimental methods used in the following examples and comparative examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples are commercially available.
[0037] Unless otherwise specified, all other reagents used in the following examples and comparative examples are commercially available products.
[0038] Example 1
[0039] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 1:1:10:200:100;
[0040] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-1.
[0041] Example 2
[0042] (1) Dilute the silica sol with some water to a SiO2 content of 10wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 1:1:10:200:100;
[0043] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-2.
[0044] Example 3
[0045] (1) Dilute the silica sol with some water to a SiO2 content of 50wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 1:1:10:200:100;
[0046] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-3.
[0047] Example 4
[0048] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 0.1:0.1:10:200:100;
[0049] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-4.
[0050] Example 5
[0051] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 0.1:0.1:0.1:2:1;
[0052] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-5.
[0053] Example 6
[0054] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 1:1:0.1:1000:100;
[0055] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-6.
[0056] Example 7
[0057] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 1:1:20:1000:100;
[0058] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-7.
[0059] Example 8
[0060] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 1:1:10:200:100;
[0061] (2) Take a dropper with a diameter of 0.5 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-8.
[0062] Example 9
[0063] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 1:1:10:200:100;
[0064] (2) Take a dropper with a diameter of 3 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-9.
[0065] Example 10
[0066] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; take titanium silicon molecular sieve powder and starch and mix them evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder and stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the starch, the silica sol (calculated as SiO2), the other part of water and the titanium silicon molecular sieve is 1:1:10:200:100;
[0067] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-10.
[0068] Example 11
[0069] (1) Dilute the silica sol with some water to a SiO2 content of 1wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 1:1:10:200:100;
[0070] (2) Take a dropper with a diameter of 2 mm and drop the suspension drop by drop into liquid nitrogen to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-11.
[0071] Example 12
[0072] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 0.2:0.2:0.1:2:1;
[0073] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-12.
[0074] Example 13
[0075] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 1:1:50:200:100;
[0076] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-13.
[0077] Example 14
[0078] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; take titanium silicon molecular sieve powder and Tianqing powder and mix them evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder and stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silicon molecular sieve is 1:1:10:2000:100;
[0079] (2) Take a dropper with a diameter of 2 mm and drop the suspension into liquid nitrogen drop by drop to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-14.
[0080] Example 15
[0081] (1) Dilute the silica sol with some water to a SiO2 content of 20wt%, and then add lauryl amide to the silica sol solution to form a uniform mixture as a binder; mix titanium silica molecular sieve powder and Tianqing powder evenly to obtain a mixed powder; add the binder and another part of water to the mixed powder, stir evenly to obtain a uniform and flowing suspension, wherein the weight ratio of the lauryl amide, the Tianqing powder, the silica sol (calculated as SiO2), the other part of water and the titanium silica molecular sieve is 1:1:10:200:100;
[0082] (2) Take a dropper with a diameter of 5 mm and drop the suspension drop by drop into liquid nitrogen to freeze into solid spheres. Then transfer the spheres to a freeze dryer for drying to obtain dried solid spheres. The vacuum degree of the freeze drying is 5 Pa and the time is 12 h. Then calcine the dried solid spheres at 500 °C for 4 h to obtain the shaped titanium silicon molecular sieve of the present invention, denoted as Cat-15.
[0083] Comparative Example 1
[0084] This comparative example illustrates the preparation of a titanium-silicon molecular sieve molding carrier according to the method described in patent CN103908975B. 2 kg of TS-1 was placed in a rotary molding machine with a diameter of 1.2 m, a depth of 450 mm, an inclination angle of 50°, and a rotation speed of 30 rpm. 1.5 kg of water was sprayed into the machine, resulting in spherical particles of 0.2-0.8 mm. Separately, TS-1 and alkaline silica sol were mixed uniformly at a weight ratio of 2.2:1. This mixture was added to the rotary mold to obtain spherical catalysts with a diameter of 1.7-2.2 mm. The spherical catalysts were then subjected to air blowing at 45°C, with water added midway, and tightened for 2 hours. They were then dried at 120°C for 24 hours, and finally calcined at 530°C for 10 hours to obtain spherical catalysts with a molecular sieve content of 85%.
[0085] Test case
[0086] This test example illustrates the reaction effect of the sample prepared in the embodiment and comparative example of the present invention on the gas-phase epoxidation reaction of propylene. All reagents used in this test example are commercially available chemically pure reagents. The concentrations of each substance after the reaction were quantitatively analyzed using gas chromatography. The instrument used was an Agilent 6890 gas chromatograph, with a molecular sieve 5A and a PoraBOND U column, and FID and TCD detectors.
[0087] Catalyst samples prepared in the above examples and comparative examples were respectively loaded onto a tubular reactor with an inner diameter of 8 mm for evaluation. The catalyst dosage was 0.4 g, and the flow rates of hydrogen, oxygen, propylene, and nitrogen were 2, 2, 2, and 14 mL / min, respectively. The reaction pressure was 0.1 MPa. After the catalyst was loaded into the reactor, the temperature was raised to 180 °C in a N2 atmosphere, and hydrogen, oxygen, and propylene were introduced to initiate the reaction. After 1 hour of reaction, the products were analyzed online.
[0088] Propylene conversion rate % = (moles of propylene in feedstock - moles of propylene in product) / moles of propylene in feedstock × 100%
[0089] propylene oxide selectivity % = (number of moles of propylene oxide in the product / total number of moles of the product) × 100%.
[0090] The results are shown in Table 1.
[0091] Table 1
[0092]
[0093]
[0094] As shown in Table 1, by adopting the technical solution described in this invention, compared with the spherical catalyst prepared in Comparative Example 1, the spherical formed titanium-silicon molecular sieves prepared in Examples 1-15 can balance mechanical properties and catalytic activity. Their fracture resistance is all above 20 N / cm, propylene conversion rate is above 3%, and propylene oxide selectivity is above 78%. In preferred Examples 1-10, the fracture resistance of the spherical formed titanium-silicon molecular sieves is all greater than 30 N / cm, propylene conversion rate is greater than 4%, and propylene oxide selectivity is greater than 80%.
[0095] The preferred 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 combinations of 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 method for forming a titanium-silicon molecular sieve, characterized in that, The method includes the following steps: (1) A pore-forming agent and silica sol are mixed to form a mixture, and then a mixture of titanium silica molecular sieve and additive powder is mixed with the mixture to obtain a suspension; (2) The suspension obtained in step (1) is dropped into liquid nitrogen to obtain solid spheres, and then the solid spheres are dried and calcined to obtain shaped titanium silicon molecular sieves.
2. The method according to claim 1, characterized in that, In step (1), the pore-forming agent is selected from at least one of surfactants such as octadecylamine salt, sodium oleate of hydroxyethyl sulfonate, and lauryl amide.
3. The method according to claim 1, characterized in that, In step (1), the SiO2 content in the silica sol is 5-50 wt%.
4. The method according to claim 1, characterized in that, In step (1), the additive is selected from at least one of tianqing powder, starch and citric acid.
5. The method according to any one of claims 1-4, characterized in that, In step (1), the weight ratio of the pore-forming agent, the auxiliary agent, the silica sol (calculated as SiO2), and the titanium-silicon molecular sieve is 0.1-2:0.1-2:1-20:
100.
6. The method according to claim 1, characterized in that, In step (2), the suspension is dripped into the liquid nitrogen through a dropper with a diameter of 0.5-3 mm.
7. The method according to claim 1, characterized in that, In step (2), the drying method is freeze drying, and the freeze drying conditions include: time of 5-30h and vacuum degree <10Pa.
8. The method according to claim 1, characterized in that, In step (2), the calcination conditions include a temperature of 300-800℃ and a time of 1-10h.
9. The shaped titanium-silicon molecular sieve prepared by the method according to any one of claims 1-8.
10. The molded titanium-silicon molecular sieve according to claim 9, characterized in that, The shaped titanium-silicon molecular sieve has a particle size of 0.5-4 mm and a breakage resistance of 20-100 N / cm.
11. The application of the shaped titanium-silicon molecular sieve according to claim 9 or 10 in the catalytic gas-phase epoxidation reaction of propylene.