Monolithic SAPO-34 molecular sieve as well as preparation method and application thereof
The preparation of integrated SAPO-34 molecular sieve through photocuring 3D printing technology solves the problems of catalyst deactivation and low mass transfer efficiency, achieves efficient and low-cost catalytic effects, and improves mechanical strength and separation convenience.
Patent Information
- Application Number
- CN202411403294.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-09
- Publication Date
- 2025-01-10
AI Technical Summary
SAPO-34 molecular sieve is prone to inactivation during the catalysis process, has low mass transfer and heat transfer efficiency, and traditional molding methods cannot accurately form porous structures, resulting in high catalytic efficiency and cost.
The photocuring 3D printing technology is used to prepare the integrated SAPO-34 molecular sieve. By optimizing the molding structure, designing a multi-stage pore gradient structure, improving the specific surface area and mass transfer efficiency, and using materials such as silane coupling agents and UV resins to achieve high precision and high-strength molding.
It significantly improves catalytic efficiency and production efficiency, reduces costs, provides higher mechanical strength and stability, and is easy to separate and recover, solving the problems of low mass transfer heat transfer efficiency and catalyst deactivation.
Smart Images
Figure FT_1
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of molecular sieve preparation, and in particular relates to an integral SAPO-34 molecular sieve and a preparation method and application thereof. Background Art
[0002] As the most in-demand and widely used basic raw materials in the chemical industry, low-carbon olefins (ethylene and propylene) are of great significance to my country's energy security in view of the high dependence of my country's petroleum resources on foreign countries. At the same time, with the background of rising international oil prices, the preparation of low-carbon olefins by non-petroleum routes such as coal-to-olefins has shown great economic advantages. Among them, the technology of preparing low-carbon olefins (MTO) from methanol is relatively mature, and many industrial units have been put into operation and achieved commercial production. Its process mainly uses molecular sieve catalysts such as ZSM-5 and SAPO-34. Among them, SAPO-34 molecular sieves show high activity and high selectivity for low-carbon olefins (especially ethylene and propylene) in the MTO reaction due to its specific skeleton structure and suitable acid strength, which makes SAPO-34 one of the preferred catalysts for the MTO reaction. However, SAPO-34 molecular sieve is prone to "deactivation" during the catalytic process, which will greatly reduce the catalytic efficiency. Therefore, starting from the macroscopic perspective of the catalyst, the catalyst is formed into an integral structure using 3D printing technology, aiming to increase its specific surface area by designing a multi-level pore gradient structure, enhance mass transfer and heat transfer efficiency, and improve conversion rate and catalytic life.
[0003] At present, the traditional molding methods include pressing molding, extrusion molding and spray molding. Among them, pressing molding and extrusion molding are limited by the mold and cannot form the internal porous structure. The catalyst particles obtained by spray molding are small, and the material loss is large and the cost is high. The preparation of integral molecular sieves by 3D printing mostly adopts direct writing printing (DIW) for molding. On the one hand, in order to improve the catalytic efficiency of molecular sieves, it is necessary to design mm-μm-nm graded porous structures, and the accuracy of direct writing molding can generally only reach 0.1mm at the lowest. It is impossible to accurately mold fine and complex structures, which affects the catalytic efficiency; on the other hand, most direct writing molecular sieve catalysts are water-based formulas, and the strength after calcination is generally low. Therefore, a large amount of carrier materials need to be added to the formula to ensure the strength after calcination, which will reduce the proportion of effective catalytic components in the components, reduce the catalytic efficiency, and also increase the filling space requirements and costs.
[0004] In the reaction process of methanol to olefins (MTO), naphthalene and other intermediates will be generated in the traditional SAPO-34 molecular sieve powder, and these intermediates will further form large molecular carbon deposits under certain conditions. These carbon deposits will block the pores of the molecular sieve, cover the active sites, and cause the catalyst to deactivate; in addition, the SAPO-34 molecular sieve has a microporous structure with a relatively small pore size. Although it has good shape selectivity, it also limits the diffusion rate of macromolecular substances in the pores, resulting in low mass transfer efficiency. In terms of the characteristics of the powder itself, the traditional SAPO-34 molecular sieve powder may have problems such as large particles and uneven particle size distribution, which will affect its dispersibility in the reaction system and thus affect the mass transfer and heat transfer efficiency. In addition, the larger particles have a relatively small specific surface area and a small contact area with the reactants, which is not conducive to the reaction. In terms of the complexity of the pore structure, the three-dimensional cross-pore structure of the SAPO-34 molecular sieve is relatively complex, which increases the difficulty and path length of the diffusion of molecules in it, and hinders the mass transfer and heat transfer process.
[0005] In summary, a high-precision and high-strength integral SAPO-34 molecular sieve preparation process is provided, which is of great significance to improving the catalytic efficiency of the molecular sieve by optimizing the molding structure. Summary of the invention
[0006] In order to overcome the technical problems existing in the prior art that SAPO-34 molecular sieve is easy to deactivate and has low mass and heat transfer efficiency, the purpose of the present invention is to provide a monolithic SAPO-34 molecular sieve and a preparation method and application thereof.
[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A method for preparing a monolithic SAPO-34 molecular sieve comprises the following steps: The SAPO-34 molecular sieve, anhydrous ethanol, a silane coupling agent and a dispersant are ball-milled to obtain a powder; Evenly mix the UV resin, the 2-functionality UV monomer, the 3-functionality UV monomer and the 6-functionality UV monomer to obtain a resin mixture; adding a photoinitiator to the resin mixture to obtain a premixed solution; Homogenize the powder, premixed liquid and low-temperature pore-forming agent to obtain a molecular sieve paste; The molecular sieve paste is subjected to light-curing 3D printing to obtain a printed green body; The printed green body is calcined to obtain a monolithic SAPO-34 molecular sieve.
[0008] A further improvement of the present invention is that the silane coupling agent is octadecyltrimethoxysilane, dodecyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane or γ-methacryloxypropyltrimethoxysilane; The dispersant is dispersant 9063, ammonium polyacrylate, sodium polyacrylate, sodium hexametaphosphate or KOS110.
[0009] A further improvement of the present invention is that the mass ratio of SAPO-34 molecular sieve, anhydrous ethanol, silane coupling agent and dispersant is 38-39:57-58:3-3.5:0.5-1.
[0010] A further improvement of the present invention is that the UV resin is polyurethane acrylate, epoxy acrylate, polyester acrylate or bisphenol A epoxy resin; The 2-functional UV monomer is 1,6-hexanediol diacrylate, tripropylene glycol diacrylate or dipropylene glycol diacrylate; The 3-functional UV monomer is trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate or pentaerythritol triacrylate; The 6-functionality UV monomer is dipentaerythritol hexaacrylate; The mass ratio of UV resin, difunctional UV monomer, trifunctional UV monomer and hexafunctional UV monomer is 5-10:30-40:40-50:10-15.
[0011] A further improvement of the present invention is that the amount of the photoinitiator is 0.5%-1% of the mass of the resin mixture; The photoinitiator is photoinitiator 819, photoinitiator TPO, photoinitiator 1173, photoinitiator 184, photoinitiator 907 or photoinitiator ITX.
[0012] A further improvement of the present invention is that the mass ratio of the powder to the premixed liquid is 2-4:1, and the amount of the low-temperature pore-forming agent is 1%-3% of the mass of the powder; The low temperature pore forming agent is PEG-400, PEG-600, PEG-800, starch or cellulose.
[0013] A further improvement of the present invention is that the laser power of printing is set to 300-400 mW, the scanning interval is set to 0.05-0.1 mm, and the layer thickness is set to 80-100 μm.
[0014] A further improvement of the present invention is that the calcination conditions are: in an inert atmosphere, the temperature is raised to 400-600° C. at a heating rate of 0.2-2° C. / min and kept at this temperature for 2-5 hours.
[0015] A monolithic SAPO-34 molecular sieve with a lateral pressure strength of more than 330N / cm.
[0016] The invention discloses an application of a monolithic SAPO-34 molecular sieve in a methanol to olefin reaction.
[0017] Compared with the powder molecular sieve in the prior art, the monolithic molecular sieve of the present invention has the following beneficial effects: The present invention forms a SAPO-34 monolithic molecular sieve by means of photocuring 3D printing. Compared with traditional molding methods such as pressing or extrusion, no mold is required, the structure can be freely designed and customized, and fine and complex structures such as internal hollow or variable density gradient structures can be formed; compared with direct writing molding in 3D printing, photocuring 3D printing has higher precision and can form more complex structures, such as three-period minimal surface structures that are more in line with fluid mechanics, etc., further improving the specific surface area of the monolithic molecular sieve while ensuring the minimum pressure drop loss. When directly writing the monolithic molecular sieve, it is often necessary to add more than 50% of the carrier component to the water-based blank due to the low strength of the water-based blank, which will greatly reduce the proportion of the effective catalytic component in the component and increase the filling space and cost. After the photocuring 3D printed monolithic molecular sieve is calcined, only less than 5% of the carbon in the component serves as a skeleton support to ensure strength, while not affecting the performance of the effective catalytic component. Photocuring 3D printing and direct writing 3D printing belong to different types of molding, and the raw materials used and the processing methods of the raw materials are different, and the preparation process is also different: the raw materials used for photocuring 3D printing are surface-modified molecular sieve powder and photosensitive resin, which are fully mixed and selectively cured by ultraviolet laser, with an accuracy of up to micron level, and can form a smooth curved surface structure, while the molecular sieve powder used for direct writing molding does not require surface modification, and the slurry is a water-based solvent. Although the preparation method is relatively simple, the molding accuracy is generally not higher than 0.4mm, and generally only a linear porous structure (wooden pile structure) can be formed. The present invention introduces photocuring 3D printing technology into SAPO-34 molecular sieve, which can accurately control the internal pore structure of the molecular sieve, for example, a three-period minimal surface structure that is very consistent with the law of gas-liquid fluid movement can be designed. The advantage of this structure is that it provides an extremely high specific surface area while reducing the pressure drop generated by gas-liquid flow inside, so that the raw gas can be used to the maximum extent when entering, improving the mass transfer and heat transfer effect, thereby improving the catalytic efficiency and production efficiency of the monolithic molecular sieve. In addition, when the printed monolithic molecular sieve is calcined under an inert atmosphere, the solidified photosensitive resin is cracked at high temperature. When the small molecule product completely escapes, a network carbon skeleton is formed at this time. The skeleton structure provides excellent strength for the calcined molecular sieve, and there is no need to add a binder to the raw material system in advance; at the same time, the carbon content formed by the cracking of the resin is small, which is conducive to the effective catalytic component in the component. The monolithic SAPO-34 molecular sieve provided by the present invention has a simple preparation process, low preparation cost, and high material utilization rate, and has broad prospects in the field of catalysis.
[0018] The monolithic molecular sieve prepared by the present invention has the following advantages: 1. Better mass transfer and heat transfer efficiency: The monolithic molecular sieve prepared by the present invention has a regular macroscopic structure, such as a specific shape and pore distribution, which is conducive to the uniform passage of the fluid, reduces the resistance and turbulence of the fluid flow, and makes the mass transfer process more efficient and orderly; its large specific surface area and continuous pore structure can provide more heat transfer interfaces and shorter heat transfer paths, thereby significantly improving the heat transfer efficiency, which is very important for reactions or processes involving heat transfer (such as catalytic reactions), and can better control the reaction temperature and improve the reaction rate and selectivity.
[0019] 2. Higher mechanical strength and stability: The integral structure makes the molecular sieve less prone to breakage or wear during use, and can withstand higher pressure and mechanical shock. In contrast, powdered molecular sieves are prone to dust during loading and use, and may cause structural damage due to uneven pressure, affecting their performance and service life. In some applications that require frequent reactions and regeneration operations, the stability advantage of integral molecular sieves is more obvious, which can maintain the integrity of the structure and the stability of performance, and reduce performance degradation caused by structural changes.
[0020] 3. Easy to separate and recycle: Monolithic molecular sieves can be easily separated from the reaction system, such as through simple filtration or screening operations, while powdered molecular sieves often require complex separation equipment and processes, such as centrifugation and sedimentation, and the separation effect may not be ideal, which can easily cause loss and waste of molecular sieves. The easy separation feature also makes monolithic molecular sieves more advantageous in terms of recycling and reuse, reducing the cost of use and the impact on the environment. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 These are macroscopic characterization images of three different structures of photocured integral SAPO-34 molecular sieves; among them, (a) is TPMS, (b) is a wooden pile, and (c) is a solid cylinder. DETAILED DESCRIPTION
[0022] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly and comprehensively understood.
[0023] The present invention provides a method for preparing an integral SAPO-34 molecular sieve. Since there are a large number of hydroxyl groups on the surface of the SAPO-34 molecular sieve powder, these hydroxyl groups make the powder surface extremely hydrophilic, while the photosensitive resin has a strong hydrophobicity, and the two are almost incompatible. Therefore, it is necessary to firstly perform silane coupling modification on the surface of the SAPO-34 molecular sieve powder so that its surface is covered with a layer of lipophilic alkyl groups, and at the same time prepare a photosensitive resin premix, that is, high-speed mixing of photosensitive monomers, diluents, photoinitiators, etc. with different functionalities, and the modified molecular sieve powder and the premix, dispersant, and low-temperature pore-forming agent are subjected to high-speed homogenization treatment in a certain proportion to obtain a smooth and non-granular light-cured 3D printed molecular sieve paste; then printing and molding are performed in sequence and calcination treatment is performed under an inert atmosphere to obtain a high-strength and high-precision integral SAPO-34 molecular sieve. Specifically, the following steps are included: Step 1. Mix SAPO-34 molecular sieve, anhydrous ethanol, a silane coupling agent and a dispersant in a mass ratio of 38-39:57-58:3-3.5:0.5-1 to obtain a mixture; wherein the silane coupling agent is octadecyltrimethoxysilane (OTMS), dodecyltrimethoxysilane (DTMS), KH-560 (γ-glycidyloxypropyltrimethoxysilane), KH-550 (γ-aminopropyltriethoxysilane) or KH-570 (γ-methacryloxypropyltrimethoxysilane), etc., and the model of the dispersant is dispersant 9063, ammonium polyacrylate (PAA-NH4), sodium polyacrylate (PAA-Na), sodium hexametaphosphate or KOS110, etc.
[0024] Step 2, adding zirconium oxide grinding balls with a mass 1.5-2 times that of the molecular sieve to the mixture obtained in step 1, and ball milling for 3-6 hours in a planetary ball mill at a rotation speed of 300-500 rpm; Step 3, drying the product obtained in step 2 at 80-100° C. in a forced air drying oven and then sieving through a 100-200 mesh sieve; Step 4: UV resin (polyurethane acrylate, epoxy acrylate, polyester acrylate or bisphenol A epoxy resin), 2-functional UV monomer (1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA) or dipropylene glycol diacrylate (DPGDA)), 3-functional UV monomer (trimethylolpropane triacrylate (TMPTA), ethoxylated pentaerythritol tetraacrylate (PPTTA) or pentaerythritol triacrylate (PETA)) and 6-functional UV monomer The resin mixture is prepared by mixing a premixed resin with a premixed resin (dipentaerythritol hexaacrylate (DPHA)) in a mass ratio of 5-10:30-40:40-50:10-15, and after being fully mixed, a resin mixture is obtained. The ground photoinitiator is added at a mass ratio of 0.5%-1% of the mass of the resin mixture to completely dissolve the ground photoinitiator in the resin mixture to obtain a premixed solution. The photoinitiator model is photoinitiator 819, photoinitiator TPO, photoinitiator 1173, photoinitiator 184, photoinitiator 907 or photoinitiator ITX, etc.
[0025] Step 5: The sieved powder in step 3 and the premixed liquid in step 4 are prepared in a mass ratio of 2-4:1, and 1%-3% of the mass of the powder is added as a low-temperature pore-forming agent, and then a high-speed homogenization treatment of 1000-2000rpm is performed to obtain a printable smooth and non-granular molecular sieve paste; wherein the low-temperature pore-forming agent is PEG-400, PEG-600, PEG-800, starch or cellulose, etc.
[0026] Step 6: Place the molecular sieve paste in step 5 into the silo of the ceramic printer, import the model into the printer computer, level the printer and perform 3D printing to obtain a printed green body, wherein the laser power is set to 300-400 mW, the scanning interval is set to 0.05-0.1 mm, and the layer thickness is set to 80-100 μm; Step 7: After cleaning and drying the printed green body in step 6, place it in a tubular furnace for degreasing in an inert atmosphere (nitrogen or argon) at a heating rate of 0.2-2°C / min, heat it to 400-600°C for calcination, and keep it at this temperature for 2-5h to obtain a carbon skeleton-supported integral SAPO-34 molecular sieve.
[0027] Example 1 Step 1, mixing SAPO-34 molecular sieve, anhydrous ethanol, dodecyltrimethoxysilane (DTMS) and dispersant 9063 in a mass ratio of 38.4:57.7:3.07:0.77 to obtain a mixture; Step 2, adding zirconium oxide grinding balls with a mass 1.5 times that of the molecular sieve to the mixture obtained in step 1, and ball milling for 3 hours in a planetary ball mill at a rotation speed of 500 rpm; Step 3, drying the product obtained in step 2 in a blast drying oven at 80°C and then sieving it through a 100-mesh sieve; Step 4, prepare bisphenol A epoxy resin, HDDA, TMPTA, and DPHA in a mass ratio of 5: 40: 45: 10, mix them thoroughly and evenly to obtain a resin mixture, add the ground photoinitiator 819 at 0.6% of the mass of the liquid, and completely dissolve it in the above resin mixture to obtain a premixed solution; Step 5: Mix the sieved powder in step 3 with the premixed liquid in step 4 at a mass ratio of 4:1, add 2% of the mass of the powder as a low-temperature pore-forming agent PEG-400, and then perform high-speed homogenization at 1500 rpm to obtain a printable, smooth, and non-granular molecular sieve paste; Step 6, placing the molecular sieve paste in step 5 into the silo of the ceramic printer, importing the model into the printer computer, and printing after leveling the printer to obtain a printed green body, wherein the laser power is set to 330 mW, the scanning interval is set to 0.05 mm, and the layer thickness is set to 80 μm; Step 7: After cleaning and drying the printed green body in step 6, place it in a tube furnace for degreasing in an inert atmosphere (argon) with a heating rate of 0.2°C / min and a maximum temperature of 600°C for 4 hours to obtain a carbon skeleton-supported monolithic molecular sieve.
[0028] The lateral pressure strength of the integral SAPO-34 molecular sieve prepared by this embodiment reaches more than 350 N / cm, and its catalytic selectivity reaches more than 95% of the molecular sieve powder with the same formula.
[0029] Example 2 Step 1, mixing SAPO-34 molecular sieve, anhydrous ethanol, octadecyltrimethoxysilane and dispersant KOS110 in a mass ratio of 38.6:57.5:3.12:0.81 to obtain a mixture; Step 2, adding zirconium oxide grinding balls with a mass 1.5 times that of the molecular sieve to the mixture obtained in step 1, and ball milling for 3 hours in a planetary ball mill at a rotation speed of 500 rpm; Step 3, drying the product obtained in step 2 in a blast drying oven at 80°C and then sieving it through a 100-mesh sieve; Step 4: prepare polyurethane acrylate, TPGDA, PPTTA, and DPHA in a mass ratio of 8:38:42:12, mix them thoroughly and evenly to obtain a resin mixture, add the ground photoinitiator TPO at 0.8% of the mass of the liquid, and completely dissolve it in the above resin mixture to obtain a premixed solution; Step 5: Mix the sieved powder in step 3 with the premixed liquid in step 4 at a mass ratio of 4:1, add 3% of the mass of the powder as a low-temperature pore-forming agent PEG-600, and then perform high-speed homogenization at 1500 rpm to obtain a printable, smooth, and non-granular molecular sieve paste; Step 6, placing the molecular sieve paste in step 5 into the silo of the ceramic printer, importing the model into the printer computer, and printing after leveling the printer to obtain a printed green body, wherein the laser power is set to 330 mW, the scanning interval is set to 0.05 mm, and the layer thickness is set to 80 μm; Step 7: After cleaning and drying the printed green body in step 6, place it in a tube furnace for degreasing in an inert atmosphere (argon) with a heating rate of 0.2°C / min and a maximum temperature of 600°C for 4 hours to obtain a carbon skeleton-supported monolithic molecular sieve.
[0030] The lateral compression strength of the integral SAPO-34 molecular sieve prepared in this embodiment reaches more than 330 N / cm. When it is used in the methanol to olefin reaction, the catalytic selectivity reaches more than 93% of the molecular sieve powder with the same formula.
[0031] Example 3 Step 1, mixing SAPO-34 molecular sieve, anhydrous ethanol, octadecyltrimethoxysilane (OTMS) and KOS110 in a mass ratio of 38:58:3.2:0.9 to obtain a mixture; Step 2, adding zirconium oxide grinding balls twice the mass of the molecular sieve to the mixture obtained in step 1, and ball milling for 6 hours in a planetary ball mill at a rotation speed of 300 rpm; Step 3, drying the product obtained in step 2 in a blast drying oven at 80°C and then sieving it through a 100-mesh sieve; Step 4, polyurethane acrylate, HDDA, PPTTA, and DPHA are prepared in a mass ratio of 8: 30:43:15, and mixed thoroughly to obtain a resin mixture, and the ground photoinitiator TPO is added at 0.8% of the mass of the liquid to completely dissolve it in the above resin mixture to obtain a premixed solution; Step 5: Mix the sieved powder in step 3 with the premixed liquid in step 4 at a mass ratio of 3.5:1, add 1% of the mass of the powder as a low-temperature pore-forming agent starch, and then perform high-speed homogenization at 1500 rpm to obtain a printable smooth and non-granular molecular sieve paste; Step 6, placing the molecular sieve paste in step 5 in the silo of the ceramic printer, importing the model into the printer computer, leveling the printer and printing to obtain a printed green body, wherein the laser power is set to 300 mW, the scanning interval is set to 0.08 mm, and the layer thickness is set to 100 μm; Step 7: After cleaning and drying the printed green body in step 6, place it in a tube furnace for degreasing in an inert atmosphere (argon) at a heating rate of 0.6°C / min, a maximum temperature of 600°C, and keep it for 2 hours to obtain a carbon skeleton-supported monolithic molecular sieve.
[0032] Example 4 Step 1, SAPO-34 molecular sieve, anhydrous ethanol, KH-560 (γ-glycidyloxypropyltrimethoxysilane) and sodium hexametaphosphate are mixed in a mass ratio of 39:57:3.0:1 to obtain a mixture; Step 2, adding zirconium oxide grinding balls with a mass 1.7 times that of the molecular sieve to the mixture obtained in step 1, and ball milling for 3 hours in a planetary ball mill at a rotation speed of 500 rpm; Step 3, drying the product obtained in step 2 in a blast drying oven at 90°C and then sieving it through a 150-mesh sieve; Step 4, epoxy acrylate, DPGDA, PETA, and DPHA are prepared in a mass ratio of 7: 35: 50: 12, and mixed thoroughly to obtain a resin mixture, and the ground photoinitiator 1173 is added at 1% of the mass of the liquid to completely dissolve it in the above resin mixture to obtain a premixed solution; Step 5: Mix the sieved powder in step 3 with the premixed liquid in step 4 at a mass ratio of 3:1, add 2% of the mass of the powder as a low-temperature pore-forming agent PEG-800, and then perform high-speed homogenization at 1500 rpm to obtain a printable, smooth, and non-granular molecular sieve paste; Step 6, placing the molecular sieve paste in step 5 in the silo of the ceramic printer, importing the model into the printer computer, and printing after leveling the printer to obtain a printed green body, wherein the laser power is set to 400 mW, the scanning interval is set to 0.07 mm, and the layer thickness is set to 90 μm; Step 7: After cleaning and drying the printed green body in step 6, place it in a tube furnace for degreasing in an inert atmosphere (argon) at a heating rate of 1°C / min, a maximum temperature of 400°C, and keep it for 5 hours to obtain a carbon skeleton-supported monolithic molecular sieve.
[0033] Example 5 Step 1, SAPO-34 molecular sieve, anhydrous ethanol, KH-550 (γ-aminopropyltriethoxysilane) and sodium polyacrylate (PAA-Na) are mixed in a mass ratio of 38.7:57.4:3.5:0.5 to obtain a mixture; Step 2, adding zirconium oxide grinding balls with a mass 1.5 times that of the molecular sieve to the mixture obtained in step 1, and ball milling for 5 hours in a planetary ball mill at a rotation speed of 400 rpm; Step 3, drying the product obtained in step 2 at 100° C. in a forced air drying oven and then sieving it through a 200-mesh sieve; Step 4, polyester acrylate, TPGDA, TMPTA, and DPHA are prepared in a mass ratio of 10: 37: 40: 14, and the mixture is fully mixed to obtain a resin mixture, and the ground photoinitiator ITX is added at 0.5% of the mass of the liquid to completely dissolve it in the resin mixture to obtain a premixed solution; Step 5: Mix the sieved powder in step 3 with the premixed liquid in step 4 at a mass ratio of 2:1, add 3% of the mass of the powder as a low-temperature pore-forming agent PEG-600, and then perform high-speed homogenization at 1500 rpm to obtain a printable, smooth, and non-granular molecular sieve paste; Step 6, placing the molecular sieve paste in step 5 into the silo of the ceramic printer, importing the model into the printer computer, and printing after leveling the printer to obtain a printed green body, wherein the laser power is set to 370 mW, the scanning interval is set to 0.1 mm, and the layer thickness is set to 85 μm; Step 7: After cleaning and drying the printed green body in step 6, place it in a tubular furnace for degreasing in an inert atmosphere (nitrogen) at a heating rate of 2°C / min, a maximum temperature of 500°C, and keep it warm for 3 hours to obtain a carbon skeleton-supported monolithic molecular sieve.
[0034] Comparative Example 1 Step 1, mixing SAPO-34 molecular sieve, anhydrous ethanol, KH-560 and dispersant sodium hexametaphosphate in a mass ratio of 38.8:57.9:3.25:0.95 to obtain a mixture; Step 2, adding zirconium oxide grinding balls with a mass 1.5 times that of the molecular sieve to the mixture obtained in step 1, and ball milling for 3 hours in a planetary ball mill at a rotation speed of 500 rpm; Step 3, drying the product obtained in step 2 in a blast drying oven at 80°C and then sieving it through a 100-mesh sieve; Step 4, epoxy acrylate, DPGDA, PPTTA, and PETA are prepared in a mass ratio of 10: 36:48:14, and mixed thoroughly to obtain a resin mixture, and the ground photoinitiator 1173 is added at 1% of the mass of the liquid to completely dissolve it in the above resin mixture to obtain a premixed solution; Step 5: Mix the sieved powder in step 3 with the premixed liquid in step 4 at a mass ratio of 4:1, add 1% of the mass of the powder as a low-temperature pore-forming agent PEG-800, and then perform high-speed homogenization at 1500 rpm to obtain a printable, smooth, and non-granular molecular sieve paste; The method of preparing the present comparative example failed to produce a complete integral SAPO-34 molecular sieve because, compared with the long-chain octadecyltrimethoxysilane (OTMS) and dodecyltrimethoxysilane (DTMS), the carbon chain of KH560 is shorter and it is difficult to penetrate into the pores and cavity system inside SAPO-34, that is, it is unable to modify the surface of the powder. Therefore, the powder treated with KH560 is difficult to be compatible with the resin, resulting in failure to print.
[0035] The present invention provides a method for preparing a photocurable 3D printed monolithic molecular sieve, which has high precision, simple process, low preparation cost, significant advantages in high catalytic efficiency and low pressure drop loss, and has broad prospects in the field of catalysis.
[0036] The present invention uses advanced photocuring 3D printing preparation technology to accurately design and control the structure of the monolithic molecular sieve, including parameters such as pore size, pore shape, and specific surface area, so as to achieve precise regulation of its performance to meet the specific needs of different application scenarios. For example, for a specific catalytic reaction, a monolithic molecular sieve with a suitable pore structure and acidic sites can be designed to improve catalytic efficiency and selectivity. In contrast, it is relatively difficult to regulate the structure and performance of powdered molecular sieves, and it is difficult to achieve a high degree of precision and customization.
[0037] See also Figure 1 In (a), (b) and (c), compared with the direct writing 3D printing method that can only form wooden pile structures, the method used in this embodiment can also form a three-period minimal surface smooth structure with zero curvature, which improves the mass transfer and heat transfer efficiency while facilitating the transmission and diffusion of fluids and reducing pressure drop. Compared with the direct writing method in 3D printing, light-curing molding can not only form simple solid cylindrical shapes and wooden pile structures (these two structures can also be directly written), but also form free smooth surface structures with zero curvature (i.e. Figure 1 The advantages of this structure have been explained in the previous content, and this structure cannot be achieved by direct writing and traditional molding methods. Figure 1 It can be seen that the advantages and characteristics of the light-curing 3D printing molding in the present invention.
[0038] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.
[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.
Claims
1. A method for preparing a monolithic SAPO-34 molecular sieve, characterized in that: The following steps are involved: The SAPO-34 molecular sieve, anhydrous ethanol, a silane coupling agent and a dispersant are ball-milled to obtain a powder; Evenly mix the UV resin, the 2-functionality UV monomer, the 3-functionality UV monomer and the 6-functionality UV monomer to obtain a resin mixture; adding a photoinitiator to the resin mixture to obtain a premixed solution; Homogenize the powder, premixed liquid and low-temperature pore-forming agent to obtain a molecular sieve paste; The molecular sieve paste is subjected to light-curing 3D printing to obtain a printed green body; The printed green body is calcined to obtain a monolithic SAPO-34 molecular sieve.
2. The method for preparing the monolithic SAPO-34 molecular sieve according to claim 1, characterized in that: The silane coupling agent is octadecyltrimethoxysilane, dodecyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane or γ-methacryloxypropyltrimethoxysilane; The dispersant is dispersant 9063, ammonium polyacrylate, sodium polyacrylate, sodium hexametaphosphate or KOS110.
3. The method for preparing the monolithic SAPO-34 molecular sieve according to claim 1, characterized in that: The mass ratio of SAPO-34 molecular sieve, anhydrous ethanol, silane coupling agent and dispersant is 38-39:57-58:3-3.5:0.5-1.
4. The method for preparing the monolithic SAPO-34 molecular sieve according to claim 1, characterized in that: UV resin is polyurethane acrylate, epoxy acrylate, polyester acrylate or bisphenol A epoxy resin; The 2-functional UV monomer is 1,6-hexanediol diacrylate, tripropylene glycol diacrylate or dipropylene glycol diacrylate; The 3-functional UV monomer is trimethylolpropane triacrylate, ethoxylated pentaerythritol tetraacrylate or pentaerythritol triacrylate; The 6-functionality UV monomer is dipentaerythritol hexaacrylate; The mass ratio of UV resin, difunctional UV monomer, trifunctional UV monomer and hexafunctional UV monomer is 5-10:30-40:40-50:10-15.
5. The method for preparing the monolithic SAPO-34 molecular sieve according to claim 1, characterized in that: The dosage of photoinitiator is 0.5%-1% of the mass of the resin mixture; The photoinitiator is photoinitiator 819, photoinitiator TPO, photoinitiator 1173, photoinitiator 184, photoinitiator 907 or photoinitiator ITX.
6. The method for preparing the monolithic SAPO-34 molecular sieve according to claim 1, characterized in that: The mass ratio of powder to premix is 2-4:1, and the dosage of low-temperature pore-forming agent is 1%-3% of the powder mass; The low temperature pore forming agent is PEG-400, PEG-600, PEG-800, starch or cellulose.
7. The method for preparing the monolithic SAPO-34 molecular sieve according to claim 1, characterized in that: The laser power for printing was set to 300-400 mW, the scanning pitch was set to 0.05-0.1 mm, and the layer thickness was set to 80-100 μm.
8. The method for preparing the monolithic SAPO-34 molecular sieve according to claim 1, characterized in that: The calcination conditions are: in an inert atmosphere, heating to 400-600°C at a heating rate of 0.2-2°C / min, and keeping the temperature for 2-5h.
9. A monolithic SAPO-34 molecular sieve prepared according to the method according to any one of claims 1 to 8, characterized in that: The lateral compression strength reaches over 330N / cm.
10. Use of the integral SAPO-34 molecular sieve prepared according to the method according to any one of claims 1 to 8 in a methanol to olefin reaction.