Super-hydrophobic structured catalytic packing, its preparation method and application

Abstract

The application belongs to the technical field of chemical process intensification and functional material, and discloses a kind of super-hydrophobic regular structure catalytic packing, its preparation method and application, the packing includes three-dimensional porous regular structure packing matrix, active component layer and super-hydrophobic layer arranged in close connection from inside to outside successively.The application aims to solve the technical problems of low utilization rate of catalytic active sites and low mass transfer efficiency caused by the covering of by-product water on the surface of traditional catalysts.The packing of the application integrates catalysis, hydrophobic drainage and separation functions, and is used as a column internal component of reaction rectification process, has good performance stability and excellent in-situ product water exclusion capacity, can significantly improve the utilization efficiency of catalyst and product yield, prolong the service life of structured catalytic packing, and is suitable for the synthesis process of maleate and other ester chemical products with water generation.

Description

Technical Field

[0001] This invention belongs to the field of chemical process intensification and functional materials technology, and in particular to a superhydrophobic ordered catalytic packing material, its preparation method and application. Background Technology

[0002] Maleic esters are important organic chemical raw materials. They can be used to produce 1,4-butanediol by catalytic hydrogenation, replacing the rapé aldehyde-acetylene process, and further synthesize tetrahydrofuran and γ-butyrolactone, etc. They are also widely used in pesticides, water purifiers, optical materials, plasticizers, paints, and coatings. The traditional synthesis method involves the esterification reaction of maleic anhydride with the corresponding alcohol under a catalyst. This process is a typical reversible reaction, producing water as a byproduct. The formation and accumulation of water inhibits the forward reaction, reducing reactant conversion and product yield.

[0003] Reactive distillation technology couples catalytic reactions and distillation separation processes within the same column, enabling the timely removal of byproduct water from the reaction zone. This breaks the limitations of chemical equilibrium and significantly improves reaction conversion rates. However, the catalyst packing material used to fill the reaction section of the reactive distillation column, which performs catalytic and separation functions, is prone to having its catalyst surface covered by generated water, forming a liquid film. This hinders the contact of reactants with catalytically active sites, reduces mass transfer efficiency and reaction rate, and prolonged water coverage can even cause deactivation or detachment of active components, thus limiting its industrial application.

[0004] A search revealed the following Chinese patent publications concerning catalysts used in the esterification of maleic anhydride: Patents CN115536528B, CN106631784A, and CN114984866B all use acidic ion exchange resin as a solid catalyst to catalyze the production of dimethyl maleate. Compared with traditional sulfuric acid catalysts, this type of catalyst is less corrosive to equipment and has high selectivity. However, resin catalysts are prone to expansion and deactivation in aqueous solutions, making it difficult to prepare them into a regular structure of catalytic packing material in the form of a coating.

[0005] Patent CN101716521A discloses a method for preparing an inorganic solid catalyst for the synthesis of dimethyl maleate. This method uses zeolite molecular sieves with silicon and aluminum oxides as the main components as the parent material. After heating and activation, ion exchange and high-temperature calcination are performed to obtain an inorganic solid catalyst with selective catalytic activity. This catalyst exhibits excellent high-temperature and high-pressure resistance and is easily separated and reusable. However, since the reaction is reversible, if the generated water is not removed from the catalyst surface in time, it will inhibit the forward reaction, resulting in a dimethyl maleate yield of only about 90%, which still needs improvement.

[0006] Patent CN110776418B discloses a method for preparing maleic esters from maleic anhydride using sulfonic acid-functionalized ionic liquids. The method involves mixing the ionic liquid with maleic anhydride and a fatty alcohol, heating the mixture to 80–140°C, and reacting for 0.5–4 hours to obtain the maleic ester. In this process, the ionic liquid acts as a catalyst, exhibiting advantages such as high catalytic activity, low deactivation rate, and recyclability. Furthermore, the process conditions are mild, and the degree of diesterization is high. However, the preparation process of the ionic liquid is relatively complex, and it is difficult to directly process it into a catalytic packing material suitable for reactive distillation. Additionally, the problem of water separation remains unresolved.

[0007] Therefore, developing a superhydrophobic, well-structured catalytic packing material with stable structure, high catalytic activity, and excellent in-situ water repulsion capability is of great theoretical significance and practical value for enhancing the esterification process of maleic anhydride. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a superhydrophobic ordered catalytic packing material, its preparation method and application.

[0009] The technical solution adopted by this invention to solve its technical problem is: A superhydrophobic structured catalytic packing material, comprising, from the inside out, a three-dimensional porous structured packing matrix, an active component layer, and a superhydrophobic layer arranged in close phase connection.

[0010] Furthermore, the active component layer includes one or more catalyst combinations selected from Beta molecular sieve, Y molecular sieve, ZSM-5 molecular sieve, heteropoly acid / silica, sulfonated zirconium oxide, phosphotungstic acid, silicotungstic acid, and phosphomolybdic acid. Alternatively, the superhydrophobic layer may include fluorosilane materials, superhydrophobic microspheres / nanoparticles, metal oxide materials, or polymer composite materials.

[0011] Furthermore, the thickness of the active component layer is 1-100 μm, preferably 20-100 μm; Alternatively, the thickness of the superhydrophobic layer is 0.5-15 μm, and the water contact angle ranges from 140-160°; Alternatively, the fluorosilane materials include trimethoxy(trifluoromethyl)silane, heptadecafluorodecyltrimethoxysilane, and heptadecafluorodecyltrichlorosilane; the superhydrophobic microspheres / nanoparticles include polystyrene microspheres and silica nanoparticles; and the polymer composite materials include polymethyl methacrylate and polyethylene terephthalate.

[0012] Furthermore, the three-dimensional porous regular structure filler matrix includes one of stainless steel corrugated wire mesh, foamed silicon carbide, wire mesh silicon carbide, and honeycomb ceramic.

[0013] The preparation method of the superhydrophobic ordered catalytic packing material as described above includes the following steps: (1) Pretreatment of three-dimensional porous regular structure filler matrix to improve surface bonding force; (2) Solid acid catalysts are loaded onto a pretreated three-dimensional porous structured packing matrix and a binder is used to form an active component layer; (3) A superhydrophobic layer was prepared on the outer surface of the solid catalyst layer by means of functional modification, outermost hydrophobic coating, micro-nano particle composite modification, sol-gel coating, in-situ polymerization and self-assembly. (4) Curing or calcining to obtain an integrated structured filler with both catalytic activity and superhydrophobic properties, namely a superhydrophobic structured catalytic filler. Alternatively, it may include the following steps: 1) Pretreatment of the three-dimensional porous structured filler matrix to improve surface adhesion; 2) The surface of solid acid catalyst particles is modified with superhydrophobic functionalization to obtain an active component layer with a superhydrophobic layer; 3) The active component with a superhydrophobic layer is loaded onto the surface of the pretreated three-dimensional porous structured filler matrix using a binder; 4) Curing or calcining yields an integrated structured filler with both catalytic activity and superhydrophobic properties, namely a superhydrophobic structured catalytic filler.

[0014] Furthermore, the pretreatment methods in step (1) include acid washing, alkali washing, or micro / nano roughening; Alternatively, the active component layer may be prepared in step (2) by one or a combination of the following methods: specifically, impregnation-calcination method, sol-gel method, in-situ synthesis method, or spraying fixation method; Alternatively, in step (3), the superhydrophobic layer may be prepared by one or a combination of the following methods: specifically, hydrophobic group functionalization modification, outermost hydrophobic coating, micro / nano particle composite modification, sol-gel coating, in-situ polymerization, or self-assembly. Alternatively, in step 2), the superhydrophobic layer may be prepared by one or a combination of the following methods: organosilylation, polymer coating, low surface energy sol-gel treatment, in-situ polymerization, or self-assembly. Alternatively, the method in step 3) may include impregnation, coating, spraying, or bonding.

[0015] Furthermore, the specific steps are as follows: First, the matrix is ​​pretreated, with the following steps: The structured packing matrix is ​​ultrasonically washed in acetone, anhydrous ethanol, and deionized water at room temperature for 10-60 min, then boiled in a 5-20% (w / w) acid / alkali solution for 5-50 min, washed with deionized water, and dried for later use, resulting in a pretreated packing matrix. Second, a solid acid catalyst is mixed with a binder and ball-milled to obtain a catalyst slurry, which is then loaded onto the surface of the pretreated packing matrix. After removal, it is dried in an oven at 50-100℃. The above steps are repeated 3-8 times to obtain a solid acid active component layer with catalyst loaded on the surface. Subsequently, a hydrophobic material is loaded onto the surface of the solid acid active component layer and dried at 80-120℃ for 30-180 min, thereby obtaining a structured catalytic packing precursor with a superhydrophobic layer. Finally, the above material is calcined in a muffle furnace at 300-600℃ for 2-8 h to obtain a superhydrophobic structured catalytic packing. Alternatively, the matrix can be pretreated first, with the following steps: The structured packing matrix is ​​ultrasonically washed in acetone, anhydrous ethanol, and deionized water at room temperature for 10-60 min, then boiled in a 5-20% (w / w) acid / alkali solution for 5-50 min. After washing with deionized water, it is dried for later use, yielding the pretreated packing matrix. Next, the solid acid catalyst is ultrasonically dispersed in a solvent containing hydrophobic materials at room temperature for 30-90 min. The reaction is stirred at 30-100℃ for 3-24 h. After the reaction, the catalyst is centrifuged at 5000-12000 rpm, and the resulting solid catalyst is washed 2-5 times and then dried in a vacuum oven at 50-90℃ for 5-20 minutes. h, a hydrophobically modified solid acid catalyst is obtained; then, the above material is mixed with a binder, ball-milled to obtain a catalyst slurry, and loaded onto the surface of the pretreated filler matrix to obtain a well-structured catalytic filler precursor with a superhydrophobic layer; finally, the above material is placed in a muffle furnace at 300-600℃ for 2-8 h to obtain a superhydrophobic well-structured catalytic filler.

[0016] The application of the superhydrophobic, well-structured catalytic packing material described above in the synthesis of maleic esters and / or ester chemical products that generate water.

[0017] The method for synthesizing maleic esters using the superhydrophobic ordered catalytic packing material described above includes the following steps: Superhydrophobic structured catalytic packing is packed into the reaction section of a reactive distillation column. Random packing or structured packing is used in the rectification and stripping sections. The reactants are maleic anhydride and the corresponding alcohol.

[0018] Furthermore, the random packing specifically includes θ ring packing, Raschig rings or Pall rings, and the structured packing specifically includes stainless steel corrugated wire mesh, foamed silicon carbide, wire mesh silicon carbide or foamed nickel; The alcohols include methanol, ethanol, and n-butanol; After the esterification reaction occurs on the surface of the superhydrophobic structured catalytic packing, the generated water molecules are difficult to stay on the catalyst surface and quickly form vapor or tiny droplets. These droplets are carried away by the rising vapor flow and removed from the top of the column, while the higher boiling point product, maleic ester, is collected from the bottom of the column, thus achieving efficient conversion of the reactants.

[0019] The advantages and positive effects of this invention are as follows: 1. The packing material of this invention integrates catalysis, hydrophobic drainage and separation functions into one unit. It is used as a column internal in the reactive distillation process. The surface of the superhydrophobic structured catalytic packing material of this invention can prevent product water from covering the catalytic active sites, providing an unobstructed mass transfer channel for the reactants. It solves the technical problems of low mass transfer efficiency and slow reaction rate caused by byproduct water covering the surface of traditional catalysts. It is suitable for the synthesis process of maleic esters and other ester chemical products that generate water.

[0020] 2. The superhydrophobic structured catalytic packing of the present invention can avoid the poisoning and erosion of solid acid catalysts by water, extend the service life of the catalytic packing, and has the advantages of high catalyst utilization and high product yield.

[0021] 3. The superhydrophobic structured catalytic packing of the present invention integrates catalysis, hydrophobic repulsion and product separation functions into one, simplifying the production process of maleic ester synthesis. At the same time, the packing of the present invention has excellent in-situ water repulsion capability.

[0022] 4. The superhydrophobic structured catalytic packing of this invention can be widely used not only in the reactive distillation process for maleic ester synthesis, but also in the production of other ester chemical products that generate water. Detailed Implementation

[0023] The present invention will be further described below with reference to the embodiments. The following embodiments are descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0024] The various experimental operations involved in the specific embodiments are all conventional techniques in the field. For parts not specifically annotated in this document, those skilled in the art can refer to various commonly used reference books, scientific and technological documents or related instructions and manuals prior to the filing date of this invention to carry out the operations.

[0025] A superhydrophobic structured catalytic packing material, comprising, from the inside out, a three-dimensional porous structured packing matrix, an active component layer, and a superhydrophobic layer arranged in close phase connection.

[0026] The packing material of this invention is applied to the production of maleic esters. A superhydrophobic, structured catalytic packing material is packed into the reaction section of a reactive distillation column. The rectification and stripping sections preferably use random packing materials such as θ-rings, Raschig rings, and Pall rings, or structured packing materials such as stainless steel corrugated wire mesh, foamed silicon carbide, wire mesh silicon carbide, and foamed nickel. The reactants are maleic anhydride and the corresponding alcohol, such as methanol, ethanol, or n-butanol. After the esterification reaction occurs on the surface of the superhydrophobic, structured catalytic packing material, the generated water molecules are difficult to remain on the catalyst surface, rapidly forming vapor or tiny droplets. These droplets are carried away by the rising vapor flow and removed from the top of the column, while the higher-boiling-point product, maleic ester, is collected from the bottom, achieving efficient conversion of the reactants. Furthermore, the active component layer includes one or more catalyst combinations selected from Beta molecular sieve, Y molecular sieve, ZSM-5 molecular sieve, heteropoly acid / silica, sulfonated zirconium oxide, phosphotungstic acid, silicotungstic acid, and phosphomolybdic acid. Alternatively, the superhydrophobic layer may include fluorosilane materials, superhydrophobic microspheres / nanoparticles, metal oxide materials, or polymer composite materials.

[0027] Furthermore, the thickness of the active component layer is 1-100 μm, preferably 20-100 μm; Alternatively, the thickness of the superhydrophobic layer is 0.5-15 μm, and the water contact angle ranges from 140-160°; Alternatively, the fluorosilane materials include trimethoxy(trifluoromethyl)silane, heptadecafluorodecyltrimethoxysilane, and heptadecafluorodecyltrichlorosilane; the superhydrophobic microspheres / nanoparticles include polystyrene microspheres and silica nanoparticles; and the polymer composite materials include polymethyl methacrylate and polyethylene terephthalate.

[0028] Furthermore, the three-dimensional porous regular structure filler matrix includes one of stainless steel corrugated wire mesh, foamed silicon carbide, wire mesh silicon carbide, and honeycomb ceramic.

[0029] The preparation method of the superhydrophobic ordered catalytic packing material as described above includes the following steps: (1) Pretreatment of three-dimensional porous regular structure filler matrix to improve surface bonding force; (2) Solid acid catalysts are loaded onto a pretreated three-dimensional porous structured packing matrix and a binder is used to form an active component layer; (3) A superhydrophobic layer was prepared on the outer surface of the solid catalyst layer by means of functional modification, outermost hydrophobic coating, micro-nano particle composite modification, sol-gel coating, in-situ polymerization and self-assembly. (4) Curing or calcining to obtain an integrated structured filler with both catalytic activity and superhydrophobic properties, namely a superhydrophobic structured catalytic filler. Alternatively, it may include the following steps: 1) Pretreatment of the three-dimensional porous structured filler matrix to improve surface adhesion; 2) The surface of solid acid catalyst particles is modified with superhydrophobic functionalization to obtain an active component layer with a superhydrophobic layer; 3) The active component with a superhydrophobic layer is loaded onto the surface of the pretreated three-dimensional porous structured filler matrix using a binder; 4) Curing or calcining yields an integrated structured filler with both catalytic activity and superhydrophobic properties, namely a superhydrophobic structured catalytic filler.

[0030] Furthermore, the pretreatment methods in step (1) include acid washing, alkali washing, or micro / nano roughening; Alternatively, the active component layer may be prepared in step (2) by one or a combination of the following methods: specifically, impregnation-calcination method, sol-gel method, in-situ synthesis method, or spraying fixation method; Alternatively, in step (3), the superhydrophobic layer may be prepared by one or a combination of the following methods: specifically, hydrophobic group functionalization modification, outermost hydrophobic coating, micro / nano particle composite modification, sol-gel coating, in-situ polymerization, or self-assembly. Alternatively, in step 2), the superhydrophobic layer may be prepared by one or a combination of the following methods: organosilylation, polymer coating, low surface energy sol-gel treatment, in-situ polymerization, or self-assembly. Alternatively, the method in step 3) may include impregnation, coating, spraying, or bonding.

[0031] Furthermore, the specific steps are as follows: First, the matrix is ​​pretreated, with the following steps: The structured packing matrix is ​​ultrasonically washed in acetone, anhydrous ethanol, and deionized water at room temperature for 10-60 min, then boiled in a 5-20% (w / w) acid / alkali solution for 5-50 min, washed with deionized water, and dried for later use, resulting in a pretreated packing matrix. Second, a solid acid catalyst is mixed with a binder and ball-milled to obtain a catalyst slurry, which is then loaded onto the surface of the pretreated packing matrix. After removal, it is dried in an oven at 50-100℃. The above steps are repeated 3-8 times to obtain a solid acid active component layer with catalyst loaded on the surface. Subsequently, a hydrophobic material is loaded onto the surface of the solid acid active component layer and dried at 80-120℃ for 30-180 min, thereby obtaining a structured catalytic packing precursor with a superhydrophobic layer. Finally, the above material is calcined in a muffle furnace at 300-600℃ for 2-8 h to obtain a superhydrophobic structured catalytic packing. Alternatively, the matrix can be pretreated first, with the following steps: The structured packing matrix is ​​ultrasonically washed in acetone, anhydrous ethanol, and deionized water at room temperature for 10-60 min, then boiled in a 5-20% (w / w) acid / alkali solution for 5-50 min. After washing with deionized water, it is dried for later use, yielding the pretreated packing matrix. Next, the solid acid catalyst is ultrasonically dispersed in a solvent containing hydrophobic materials at room temperature for 30-90 min. The reaction is stirred at 30-100℃ for 3-24 h. After the reaction, the catalyst is centrifuged at 5000-12000 rpm, and the resulting solid catalyst is washed 2-5 times and then dried in a vacuum oven at 50-90℃ for 5-20 minutes. h, a hydrophobically modified solid acid catalyst is obtained; then, the above material is mixed with a binder, ball-milled to obtain a catalyst slurry, and loaded onto the surface of the pretreated filler matrix to obtain a well-structured catalytic filler precursor with a superhydrophobic layer; finally, the above material is placed in a muffle furnace at 300-600℃ for 2-8 h to obtain a superhydrophobic well-structured catalytic filler.

[0032] The application of the superhydrophobic, well-structured catalytic packing material described above in the synthesis of maleic esters and / or ester chemical products that generate water.

[0033] The method for synthesizing maleic esters using the superhydrophobic ordered catalytic packing material described above includes the following steps: Superhydrophobic structured catalytic packing is packed into the reaction section of a reactive distillation column. Random packing or structured packing is used in the rectification and stripping sections. The reactants are maleic anhydride and the corresponding alcohol.

[0034] Furthermore, the random packing specifically includes θ ring packing, Raschig rings or Pall rings, and the structured packing specifically includes stainless steel corrugated wire mesh, foamed silicon carbide, wire mesh silicon carbide or foamed nickel; The alcohols include methanol, ethanol, and n-butanol; After the esterification reaction occurs on the surface of the superhydrophobic structured catalytic packing, the generated water molecules are difficult to stay on the catalyst surface and quickly form vapor or tiny droplets. These droplets are carried away by the rising vapor flow and removed from the top of the column, while the higher boiling point product, maleic ester, is collected from the bottom of the column, thus achieving efficient conversion of the reactants.

[0035] The specific preparation and testing methods are as follows: Example 1 A superhydrophobic structured catalytic packing material, comprising, from the inside out, a three-dimensional porous structured packing matrix, an active component layer, and a superhydrophobic layer arranged in close phase connection.

[0036] The preparation method of the above-mentioned superhydrophobic ordered catalytic packing includes the following steps: First, the matrix is ​​pretreated: the wire mesh silicon carbide packing matrix is ​​ultrasonically washed at room temperature for 15 min in acetone, anhydrous ethanol, and deionized water, respectively, and then boiled in a 10% sodium hydroxide alkaline solution for 30 min. After washing with deionized water, it is dried for later use. Second, the active component ZSM-5 molecular sieve catalyst is loaded onto the pretreated wire mesh silicon carbide packing using an dip-coating method. The specific steps are as follows: 16 g of ZSM-5 molecular sieve powder is mixed with 2 g of soluble starch, 2 g of polyethylene glycol, and 2 g of silica sol, and ball-milled to obtain a ZSM-5 molecular sieve slurry. The pretreated wire mesh silicon carbide matrix is ​​immersed in this solution for 5 min, and then dried in an oven at 50°C. The above immersion-drying steps are repeated 3 times to obtain a solid acid active component layer with ZSM-5 molecular sieve loaded on the surface. Subsequently, 350 g of ZSM-5 molecular sieve is taken and dried in an oven at 50°C. Using 80.0% ethanol aqueous solution as solvent, 7 mL of hexadecyltrimethoxysilane (HDTMS) and 32 mL of tetraethyl silicate (TEOS) (HDTMS to TEOS molar ratio of 0.12) were slowly added. After stirring at room temperature for 10 min, 12.5 mL of 25% ammonia water was added, and stirring was continued at 60℃ for 2 h to obtain a hydrophobic sol. The hydrophobic sol was then sprayed onto the surface of a solid acid active component layer of ZSM-5 molecular sieve, and dried at 120℃ for 180 min. The spraying-drying step was repeated 3 times to obtain a prestructured catalytic packing precursor with a superhydrophobic layer. Finally, the material was calcined in a muffle furnace at 400℃ for 6 h to obtain a superhydrophobic ZSM-5 / SiC prestructured catalytic packing. The thickness of the active component layer of the obtained regular structure packing is 35±0.5 μm, the thickness of the hydrophobic layer is 5±0.5 μm, and the water contact angle is 155±3°.

[0037] Comparative Example 1 Except for the absence of a hydrophobic sol layer, the pretreatment of the filler matrix and the preparation methods and raw materials of the solid acid active component layer are the same as in Example 1, resulting in a ZSM-5 / SiC regular structure catalytic filler with only a solid acid active component layer.

[0038] Application Example 1 The catalytic packing materials prepared in Example 1 and Comparative Example 1 were respectively loaded into the reaction section of a reactive distillation column for maleic ester synthesis performance evaluation. The product yield results are shown in Table 1. The operating pressure of the reactive distillation column was 101.32 kPa, the operating temperature was 110 °C, the reflux ratio was 3:1, the molar ratio of maleic anhydride to alcohol was 1:4, and maleic ester product was obtained from the bottom of the column. The feed position was 13. The theoretical plate number of the reaction section in the reactive distillation column was 15, the theoretical plate number of the rectification section was 12, and the theoretical plate number of the stripping section was 14. Both the rectification and stripping sections were packed with θ-ring packing.

[0039] Table 1. Comparison of product yields of catalytic packing materials in reactive distillation for the production of maleic esters.

[0040] As shown in Table 1, compared to Comparative Example 1, the yield of dimethyl maleate increased by 22.1% and the yield of diethyl maleate increased by 25.0% in Example 1. Furthermore, in Example 1, the product yield decreased by only 0.95% after 200 hours of operation, while in Comparative Example 1, the product yield decreased by 12.69% after 200 hours. This demonstrates that the superhydrophobic, well-structured catalytic packing of the present invention not only prevents product water from covering the catalytic active sites and improving product yield, but also avoids the poisoning and erosion effects of water on solid acid catalysts, extending the service life of the catalytic packing.

[0041] Example 2 A superhydrophobic structured catalytic packing material, comprising, from the inside out, a three-dimensional porous structured packing matrix, an active component layer, and a superhydrophobic layer arranged in close phase connection.

[0042] The preparation method of the above-mentioned superhydrophobic ordered catalytic packing includes the following steps: First, the matrix was pretreated: the nickel foam matrix was ultrasonically washed for 20 min at room temperature in acetone, anhydrous ethanol, and deionized water, respectively. Then, it was boiled in a 10% sodium hydroxide solution for 10 min, washed with deionized water, and dried for later use. Second, the active component, phosphotungstic acid / silica catalyst, was hydrophobically modified. The specific procedure was as follows: 10 g of phosphotungstic acid / silica catalyst was ultrasonically dispersed in a solution containing n-hexane for 60 min at room temperature. Propyltrimethoxysilane was added at a mass ratio (propyltrimethoxysilane:phosphotungstic acid / silica = 0.8:1), and the mixture was stirred at 65℃ for 14 h. After the reaction, the mixture was centrifuged at 8000 rpm, and the resulting solid catalyst was washed three times with n-hexane and then dried in a vacuum oven at 65℃ for 18 h to obtain the hydrophobically modified phosphotungstic acid / silica sample. Subsequently, 10 g of the hydrophobically modified catalyst powder, 2 g of polyethylene glycol, and 3 g of... Acidic silica sol (30% solid content) and nano-alumina sol (20% solid content) (acidic silica sol to nano-alumina sol mass ratio of 2:1) were mixed in a certain proportion, with 35 g of deionized water as the solvent. The mixture was ball-milled for 30 min to prepare a catalyst slurry. The pretreated nickel foam was then immersed in the slurry using the dip-coating method at a pulling speed of 15 mm·min. -1 After being removed, the material was dried at 80 °C for 120 min to obtain a pre-structured catalytic packing precursor with a superhydrophobic layer. Finally, the material was calcined in a muffle furnace at 300 °C for 2 h to obtain a superhydrophobic phosphotungstic acid / silica@nickel foam pre-structured catalytic packing. The thickness of the active component in the obtained pre-structured catalytic packing was 42±0.5 μm, and the water contact angle was 146±2°.

[0043] Comparative Example 2 Except for the absence of hydrophobic modification of the phosphotungstic acid / silica catalyst, the pretreatment of the filler matrix and the preparation methods and raw materials of the solid acid active component layer are the same as in Example 2, resulting in a phosphotungstic acid / silica@nickel foam structured catalytic filler with only a solid acid active component layer.

[0044] Application Example 2 The structural catalytic packings prepared in Example 2 and Comparative Example 2 were respectively loaded into the reaction section of a reactive distillation column for maleic ester synthesis performance evaluation. The product yield results are shown in Table 2. The operating pressure of the reactive distillation column was 101.32 kPa, the operating temperature was 110℃, the reflux ratio was 2:1, the molar ratio of maleic anhydride to alcohol was 1:4, and maleic ester product was obtained from the bottom of the column. The feed position was 8. The theoretical plate number of the reaction section in the reactive distillation column was 20, the theoretical plate number of the rectification section was 7, and the theoretical plate number of the stripping section was 10. Both the rectification and stripping sections were packed with θ-ring packing.

[0045] Table 2. Comparison of product yields of catalytic packing materials in reactive distillation for the production of maleic esters.

[0046] As shown in Table 2, Example 2 improved the yield of dimethyl maleate by 24.2% and the yield of diethyl maleate by 29.6% compared to Comparative Example 2. Furthermore, in Example 2, the product yield decreased by only 0.86% after 200 hours of operation, while in Comparative Example 2, the product yield decreased by 13.06% after 200 hours. This demonstrates that the superhydrophobic, well-structured catalytic packing of the present invention not only prevents product water from covering the catalytic active sites and improving product yield, but also avoids the poisoning and erosion effects of water on solid acid catalysts, extending the service life of the catalytic packing.

[0047] Example 3 A superhydrophobic structured catalytic packing material, comprising, from the inside out, a three-dimensional porous structured packing matrix, an active component layer, and a superhydrophobic layer arranged in close phase connection.

[0048] The preparation method of the above-mentioned superhydrophobic ordered catalytic packing includes the following steps: First, the matrix was pretreated: the stainless steel corrugated wire mesh filler was ultrasonically washed for 20 min each in acetone, anhydrous ethanol, and deionized water, then boiled in a 10% sodium hydroxide solution for 10 min, washed with deionized water, and dried for later use. Second, 10 g of Beta molecular sieve, 2 g of polyethylene glycol, and 3 g of acidic silica sol (30% solid content) and nano-alumina sol (20% solid content) (silicone rubber to aluminum rubber mass ratio of 2:1) were mixed in a specific ratio with 35 g of deionized water as the solvent, and ball-milled for 30 min to obtain a Beta molecular sieve slurry. The pretreated stainless steel corrugated wire mesh filler was then immersed in the slurry using an dip-coating method at a speed of 15 mm·min. -1After removal, the material was dried at 80 °C for 2 h to obtain a solid acid active component layer with Beta molecular sieve loaded on the surface. Subsequently, 30 g of superhydrophobic nano-SiO2 material was placed in a mixture of heptadecafluorodecyltrimethoxysilane, epoxy resin, and ethyl acetate (mass ratio of heptadecafluorodecyltrimethoxysilane:epoxy resin:ethyl acetate = 1:8:100) (mass ratio of superhydrophobic nano-SiO2 to the mixture was 2:8), ultrasonicated for 15 min, stirred for 20 min, and then sprayed onto the surface of Beta molecular sieve / stainless steel corrugated wire mesh packing. The mixture was then dried in an oven at 85 °C for 2 h to obtain a pre-structured catalytic packing precursor with a superhydrophobic layer. Finally, the above material was calcined in a muffle furnace at 500 °C for 4 h to obtain a superhydrophobic Beta molecular sieve / stainless steel corrugated wire mesh pre-structured catalytic packing. The thickness of the active component of the obtained regular structure catalytic packing is 58±0.5 μm, the thickness of the hydrophobic layer is 6.5±0.5 μm, and the water contact angle is 157±2°.

[0049] Comparative Example 3 Except for the absence of a superhydrophobic layer, the pretreatment of the packing matrix and the preparation methods and raw materials of the solid acid catalyst layer are the same as in Example 3, resulting in a Beta molecular sieve / stainless steel corrugated wire mesh structured catalytic packing with only a solid acid active component layer.

[0050] Application Example 3 The structural catalytic packing materials prepared in Example 3 and Comparative Example 3 were respectively loaded into the reaction section of a reactive distillation column for maleic ester synthesis performance evaluation. The product yield results are shown in Table 3. The operating pressure of the reactive distillation column was 101.32 kPa, the operating temperature was 110℃, the reflux ratio was 2:1, the molar ratio of maleic anhydride to alcohol was 1:4, and maleic ester product was obtained from the bottom of the column. The feed position was 14. The theoretical plate number of the reaction section in the reactive distillation column was 25, the theoretical plate number of the rectification section was 13, and the theoretical plate number of the stripping section was 15. Both the rectification and stripping sections were packed with θ-ring packing.

[0051] Table 3. Comparison of product yields of catalytic packing materials in reactive distillation for the production of maleic esters.

[0052] As shown in Table 3, Example 3 improved the yield of dimethyl maleate by 19.8% and the yield of diethyl maleate by 22.3% compared to Comparative Example 3. Furthermore, in Example 3, the product yield decreased by only 0.91% after 200 hours of operation, while in Comparative Example 3, the product yield decreased by 15.6% after 200 hours. This demonstrates that the superhydrophobic, well-structured catalytic packing of the present invention not only prevents product water from covering the catalytic active sites and improving product yield, but also avoids the poisoning and erosion effects of water on solid acid catalysts, extending the service life of the catalytic packing.

[0053] Although embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the scope of the invention is not limited to the contents disclosed in the embodiments.

Claims

1. A superhydrophobic, structured catalytic packing material, characterized in that: The packing material comprises, from the inside out, a three-dimensional porous, regularly structured packing matrix with tightly connected phases, an active component layer, and a superhydrophobic layer.

2. The superhydrophobic structured catalytic packing material according to claim 1, characterized in that: The active component layer includes one or more catalyst combinations selected from Beta molecular sieve, Y molecular sieve, ZSM-5 molecular sieve, heteropoly acid / silica, sulfonated zirconium oxide, phosphotungstic acid, silicotungstic acid, and phosphomolybdic acid. Alternatively, the superhydrophobic layer may include fluorosilane materials, superhydrophobic microspheres / nanoparticles, metal oxide materials, or polymer composite materials.

3. The superhydrophobic structured catalytic packing material according to claim 1, characterized in that: The thickness of the active component layer is 1-100 μm; Alternatively, the thickness of the superhydrophobic layer is 0.5-15 μm, and the water contact angle ranges from 140-160°; Alternatively, the fluorosilane materials include trimethoxy(trifluoromethyl)silane, heptadecafluorodecyltrimethoxysilane, and heptadecafluorodecyltrichlorosilane; the superhydrophobic microspheres / nanoparticles include polystyrene microspheres and silica nanoparticles; and the polymer composite materials include polymethyl methacrylate and polyethylene terephthalate.

4. The superhydrophobic, well-structured catalytic packing material according to any one of claims 1 to 3, characterized in that: The three-dimensional porous structured filler matrix includes one of stainless steel corrugated wire mesh, foamed silicon carbide, wire mesh silicon carbide, and honeycomb ceramic.

5. The method for preparing the superhydrophobic, structured catalytic packing material according to any one of claims 1 to 4, characterized in that: Includes the following steps: (1) Pretreatment of three-dimensional porous regular structure filler matrix to improve surface bonding force; (2) Solid acid catalysts are loaded onto a pretreated three-dimensional porous structured packing matrix and a binder is used to form an active component layer; (3) A superhydrophobic layer was prepared on the outer surface of the solid catalyst layer by means of functional modification, outermost hydrophobic coating, micro-nano particle composite modification, sol-gel coating, in-situ polymerization and self-assembly. (4) Curing or calcining to obtain an integrated structured filler with both catalytic activity and superhydrophobic properties, namely a superhydrophobic structured catalytic filler. Alternatively, it may include the following steps: 1) Pretreatment of the three-dimensional porous structured filler matrix to improve surface adhesion; 2) The surface of solid acid catalyst particles is modified with superhydrophobic functionalization to obtain an active component layer with a superhydrophobic layer; 3) The active component with a superhydrophobic layer is loaded onto the surface of the pretreated three-dimensional porous structured filler matrix using a binder; 4) Curing or calcining yields an integrated structured filler with both catalytic activity and superhydrophobic properties, namely a superhydrophobic structured catalytic filler.

6. The preparation method according to claim 5, characterized in that: The pretreatment methods in step (1) include acid washing, alkali washing, or micro / nano roughening; Alternatively, the active component layer may be prepared in step (2) by one or a combination of the following methods: specifically, impregnation-calcination method, sol-gel method, in-situ synthesis method, or spraying fixation method; Alternatively, in step (3), the superhydrophobic layer may be prepared by one or a combination of the following methods: specifically, hydrophobic group functionalization modification, outermost hydrophobic coating, micro / nano particle composite modification, sol-gel coating, in-situ polymerization, or self-assembly. Alternatively, in step 2), the superhydrophobic layer may be prepared by one or a combination of the following methods: organosilylation, polymer coating, low surface energy sol-gel treatment, in-situ polymerization, or self-assembly. Alternatively, the method in step 3) may include impregnation, coating, spraying, or bonding.

7. The preparation method according to claim 5, characterized in that: The specific steps are as follows: First, the matrix is ​​pretreated, with the following steps: The structured packing matrix is ​​ultrasonically washed in acetone, anhydrous ethanol, and deionized water at room temperature for 10-60 min, then boiled in a 5-20% (w / w) acid / alkali solution for 5-50 min, washed with deionized water, and dried for later use, resulting in a pretreated packing matrix. Second, a solid acid catalyst is mixed with a binder and ball-milled to obtain a catalyst slurry, which is then loaded onto the surface of the pretreated packing matrix. After removal, it is dried in an oven at 50-100℃. The above steps are repeated 3-8 times to obtain a solid acid active component layer with catalyst loaded on the surface. Subsequently, a hydrophobic material is loaded onto the surface of the solid acid active component layer and dried at 80-120℃ for 30-180 min, thereby obtaining a structured catalytic packing precursor with a superhydrophobic layer. Finally, the above material is calcined in a muffle furnace at 300-600℃ for 2-8 h to obtain a superhydrophobic structured catalytic packing. Alternatively, the matrix can be pretreated first, with the following steps: The structured packing matrix is ​​ultrasonically washed in acetone, anhydrous ethanol, and deionized water at room temperature for 10-60 min, then boiled in a 5-20% (w / w) acid / alkali solution for 5-50 min. After washing with deionized water, it is dried for later use, yielding the pretreated packing matrix. Next, the solid acid catalyst is ultrasonically dispersed in a solvent containing hydrophobic materials at room temperature for 30-90 min. The reaction is stirred at 30-100℃ for 3-24 h. After the reaction, the catalyst is centrifuged at 5000-12000 rpm, and the resulting solid catalyst is washed 2-5 times and then dried in a vacuum oven at 50-90℃ for 5-20 minutes. h, a hydrophobically modified solid acid catalyst is obtained; then, the above material is mixed with a binder, ball-milled to obtain a catalyst slurry, and loaded onto the surface of the pretreated filler matrix to obtain a well-structured catalytic filler precursor with a superhydrophobic layer; finally, the above material is placed in a muffle furnace at 300-600℃ for 2-8 h to obtain a superhydrophobic well-structured catalytic filler.

8. The use of the superhydrophobic, ordered catalytic packing material as described in any one of claims 1 to 4 in the synthesis of maleic esters and / or ester chemical products that generate water.

9. A method for synthesizing maleic esters using the superhydrophobic, well-structured catalytic packing material as described in any one of claims 1 to 4, characterized in that: Includes the following steps: Superhydrophobic structured catalytic packing is packed into the reaction section of a reactive distillation column. Random packing or structured packing is used in the rectification and stripping sections. The reactants are maleic anhydride and the corresponding alcohol.

10. The method according to claim 9, characterized in that: The random packing specifically includes θ ring packing, Raschig rings or Pall rings, and the structured packing specifically includes stainless steel corrugated wire mesh, foamed silicon carbide, wire mesh silicon carbide or foamed nickel. The alcohols include methanol, ethanol, and n-butanol.

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