A solid-liquid phase o-alkylation reaction catalyst and a preparation method thereof

Abstract

This invention provides a solid-liquid phase O-alkylation reaction catalyst and its preparation method. The catalyst consists of an organic compound, a metal oxide, and excipients; the metal oxide is a magnesium-aluminum mixed oxide, the organic compound is sulfonated chitosan, and the excipients are a silane coupling agent, methylsilane, anhydrous toluene, anhydrous ethanol, deionized water, glacial acetic acid solution, sodium hydroxide solution, and anhydrous dichloromethane. The sulfonated chitosan is chemically loaded onto the magnesium-aluminum mixed oxide, ensuring the catalyst possesses dual acid-base catalytic centers, improving the reactivity of the raw materials, enhancing the catalyst's stability, facilitating post-reaction separation, and extending its cycle life.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a solid-liquid phase O-alkylation reaction catalyst reaction and its preparation method. Background Technology

[0002] O-alkylation refers to the reaction in which hydrogen atoms in the hydroxyl groups of alcohols or phenols are replaced by alkyl groups to form ether compounds. Technological development in O-alkylation mainly focuses on innovation in catalysts and reaction conditions. Currently, industrial production uses strong bases to convert phenols or alcohols into oxygen anions, which then react with active alkylating agents, resulting in numerous side reactions. Quaternary ammonium salts or quaternary phosphonium salts are used as phase transfer catalysts for O-alkylation, but their removal is difficult. The preparation of some ethers requires solid-liquid phase reactions, where one raw material has a high melting point and is a solid, while the other is a liquid. Therefore, the solid and liquid raw materials are reacted at the solid-liquid interface.

[0003] Solid catalysts for O-alkylation reactions in both solid and liquid phases offer significant advantages, including ease of recovery and recycling, aligning with green chemistry requirements. Solid base catalysts, however, suffer from low stability, easy loss of active components, and frequent deactivation. Solid acid catalysts also exhibit similar problems. Despite substantial progress in O-alkylation catalyst development, low catalyst activity, short catalytic lifetime, and poor recyclability remain key constraints on their large-scale application. Therefore, researching novel solid catalysts is crucial. Summary of the Invention

[0004] One objective of this invention is to address the problems of numerous side reactions in strong base O-alkylation reactions and the difficulty in removing phase transfer catalysts, by providing an organic-metal solid-phase catalyst, wherein the organic is sulfonated chitosan and the metal is a magnesium-aluminum mixed oxide.

[0005] Another objective of this invention is to address the problem of loss of traditional solid acid / base catalysts by using a magnesium-aluminum mixed oxide, which serves as both a framework and an anchor for organic materials.

[0006] Another objective of this invention is to ensure uniform dispersion of the catalyst sites. The organic material used is chitosan, which can chelate magnesium and aluminum ions, helping to form smaller and more stable metal oxide particles and preventing agglomeration.

[0007] Another objective of this invention is to provide a method for preparing a regenerable solid-phase O-alkylation catalyst, which can produce a regenerable solid-phase O-alkylation catalyst.

[0008] To achieve the above objectives, this invention discloses a solid-liquid phase O-alkylation catalyst, which is composed of an organic compound, a metal oxide, and excipients. The organic compound is sulfonated chitosan, the metal oxide is a magnesium-aluminum mixed oxide, and the excipients are anhydrous toluene, anhydrous ethanol, deionized water, glacial acetic acid solution, sodium hydroxide solution, and anhydrous dichloromethane. This catalyst is a solid-phase catalyst; the organic-inorganic structure ensures its stability. The sulfonated chitosan is anchored to the magnesium-aluminum oxide by forming hydrogen bonds or coordination bonds with the hydroxyl groups of the magnesium-aluminum oxide through its amino and hydroxyl groups on its molecular chain. This effectively inhibits the loss of sulfonic acid groups in the reaction system, solving the problem of easy loss of active components in solid acid catalysts. The cross-linked structure formed by the chitosan skeleton after sulfonation, combined with the layered mesoporous characteristics of the magnesium-aluminum oxide, constructs a multi-level pore structure, which is beneficial for the diffusion of macromolecular reactants and reduces carbon deposition caused by limited diffusion. This invention addresses the problem of carbon buildup and deactivation in solid catalysts. The present invention provides a solid-phase catalyst with a dual-center acid-base structure featuring nanoscale spatial separation. The sulfonated chitosan achieves nanoscale spatial separation from the magnesium aluminum oxide surface via the C3 alkyl chain of a silane coupling agent, forming acid-base synergistic microdomains. Simultaneously, methylsilane constructs a hydrophobic gradient layer on the catalyst surface, forming a core-shell interface structure of "hydrophobic shell - acid-base active core." The organic portion of the sulfonated chitosan provides protic acid centers, and the magnesium aluminum oxide provides basic centers. Reactant molecules form a base-acid dual-activation transition state on the catalyst solid-phase surface.

[0009] Preferably, the catalyst is prepared by weight of 10-20 parts of magnesium-aluminum mixed oxide, 4-10 parts of silane coupling agent, 1-5 parts of chitosan, 7-15 parts of chlorosulfonic acid, and 1-2 parts of methylsilane. Silane coupling agents, acting as organic-inorganic interface bridges, link magnesium-aluminum mixed oxides and sulfonated chitosan together. One end of the coupling agent undergoes a condensation reaction with the hydroxyl groups on the surface of the magnesium-aluminum oxides, forming a chemical bond M(metal)-O-Si. The other end can react and entangle with the organic chitosan molecular chains. The magnesium-aluminum mixed oxides serve as the inorganic framework and base center, while chitosan acts as the organic framework and sulfonic acid group support. Chlorosulfonic acid sulfonates the chitosan, introducing sulfonic acid group catalytic centers into the catalyst. Methylsilane introduces methyl groups into the catalyst framework, forming hydrophobic microdomains. These hydrophobic microdomains and the hydrophilic sulfonic acid group regions constitute a surface chemical gradient. Through hydrophobic interactions, solid phenolic substrates are preferentially adsorbed, while water molecules are repelled to inhibit the hydrosolubilization and deactivation of the sulfonic acid groups, achieving directional enrichment of reactants and selective desorption of products. The methyl groups can also provide steric hindrance, suppressing the side reaction of excessive alkylation of the target product and improving product selectivity.

[0010] Preferably, the magnesium-aluminum mixed oxide is prepared from 10-20 parts of magnesium nitrate hexahydrate, 20-40 parts of aluminum nitrate nonahydrate, 8-16 parts of sodium hydroxide solution, and 4-10 parts of sodium carbonate. In the co-precipitation process, the magnesium-aluminum mixed oxide of the present invention is mixed at the atomic level. The resulting magnesium-aluminum oxide is not a simple mechanical mixture but forms a highly miscible solid solution or spinel precursor, generating more mesopores, which is beneficial for the bonding of chitosan macromolecules.

[0011] Preferably, the silane coupling agent is 3-glycidyl etheroxypropyltrimethoxysilane, and the chitosan has a particle size of 80-100 mesh.

[0012] Preferably, the concentration of the glacial acetic acid solution is 1%, and the concentration of the sodium hydroxide solution is 1-2%.

[0013] This invention also provides a method for preparing a solid-liquid phase O-alkylation catalyst, comprising the following steps: S1. Preparation of magnesium-aluminum mixed oxide; S2. Silanized magnesium-aluminum mixed oxide: The magnesium-aluminum mixed oxide was vacuum dried, then placed in anhydrous toluene and ultrasonically dispersed. Under nitrogen atmosphere, 3-glycidyl etheroxypropyltrimethoxysilane and methylsilane were added, and the mixture was refluxed. Then, it was centrifuged, washed with toluene and ethanol in sequence, and dried to obtain silanized magnesium-aluminum mixed oxide. S3. Prepare a chitosan solution by dissolving chitosan in glacial acetic acid solution and stirring until completely dissolved. Then add dilute sodium hydroxide to adjust the pH to 5.0-6.0. S4. The silanized magnesium aluminum mixed oxide is ultrasonically dispersed in deionized water, then chitosan solution is added, stirred, centrifuged to obtain solid, washed with deionized water 3-5 times, washed with ethanol once, and vacuum dried to obtain chitosan-alkylated magnesium aluminum mixed oxide. S5. Chitosan-alkylated magnesium aluminum mixed oxide was placed in anhydrous dichloromethane and cooled in an ice-water bath. Then, chlorosulfonic acid was slowly added. After the addition was complete, the mixture was stirred for 4 hours. Then, ice water was added, the solid was separated by centrifugation, washed with deionized water, washed with anhydrous ethanol, and dried under vacuum to obtain the final product, the O-alkylation reaction catalyst.

[0014] Preferably, the preparation of magnesium-aluminum mixed oxide in step S1 includes the following steps: Magnesium nitrate hexahydrate and aluminum nitrate nonahydrate were dissolved in deionized water to prepare a mixed salt solution. Sodium carbonate was poured into sodium hydroxide solution to prepare an alkaline solution. The mixed salt solution and the alkaline solution were mixed together, stirred vigorously, and allowed to stand at 60-65℃ for 24 hours. The solution was then filtered, washed until neutral, and dried at 80℃ for 12 hours to obtain magnesium aluminum hydrotalcite. Magnesium-aluminum hydrotalcite was placed in a muffle furnace and heated to 500℃ at a rate of 5℃ / min. It was then calcined at this constant temperature for 5 hours and allowed to cool naturally to obtain a magnesium-aluminum mixed oxide.

[0015] Preferably, in step S2, the vacuum drying temperature is 120-125℃ for 2 hours; the reflux reaction temperature is 110-115℃ for 24 hours; the centrifugation speed is 6000-7000 rpm, the centrifugation time is 5-10 minutes, and the drying temperature is 60℃.

[0016] Preferably, in step S4, the stirring temperature is 20-25℃, the stirring time is 24h, the centrifugation speed is 5000-6000rpm, the centrifugation time is 5-10min, and the vacuum drying is performed at 50℃.

[0017] Preferably, in step S5, the ice-water bath is cooled to 0°C; the entire dropping process is maintained at 0°C; the centrifugation speed is 4000-5000 rpm, and the centrifugation time is 5-10 min; the vacuum drying temperature is 50°C, and the drying time is 1 h.

[0018] The beneficial effects of this invention are: (1) Improve the structural stability of the catalyst by bonding sulfonated chitosan and magnesium-aluminum mixed oxide with silane coupling agent. The magnesium-aluminum mixed oxide has good dispersion uniformity and good thermal stability, providing solid rigid support. This solves the problem that the active components of traditional supported catalysts are easy to fall off in liquid phase reaction, significantly improving the stability and persistence of the catalyst, and can support its use in O-alkylation reaction in solid and liquid phase.

[0019] (2) High catalytic efficiency: The catalyst forms a solid-liquid interface confinement effect through the adjacent acid-base dual centers at the nanoscale, which simultaneously activates two solid phenols and liquid epoxide substrates; the spatial isolation of the silane coupling agent prevents the acid-base centers from neutralizing each other, and the hydrophobic gradient layer constructed by methylsilane promotes the directional mass transfer of the substrate, which significantly improves the efficiency and selectivity of O-alkylation reaction in the solid-liquid phase.

[0020] (3) The catalyst is green, environmentally friendly and renewable. The catalyst uses renewable biomass resources - chitosan and is a solid catalyst, which is easy to separate and recover from the reaction system, in line with the direction of green development. After it is deactivated, it can be regenerated by mild chemical washing, which further enhances its sustainability.

[0021] (4) Extend the service life of the catalyst. Methylsilane is introduced into the catalyst. Methyl groups are present on the catalyst surface, which can form hydrophobic microdomains, reduce the concentration of water molecules around the sulfonic acid group, and slow down its deactivation rate. The presence of methyl groups is not conducive to the aggregation of large carbon molecules, reducing the amount of carbon on the surface and extending the service life. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments.

[0023] General Implementation Examples: Catalyst formulation: 10-20 parts magnesium-aluminum mixed oxide, 4-10 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1-5 parts chitosan, 7-15 parts chlorosulfonic acid, and 1-2 parts methylsilane. Formula for magnesium-aluminum mixed oxides: 10-20 parts magnesium nitrate hexahydrate, 20-40 parts aluminum nitrate nonahydrate, 8-16 parts sodium hydroxide solution (sodium hydroxide concentration is 1-2%), and 4-10 parts sodium carbonate.

[0024] Preparation method of magnesium-aluminum mixed oxide: a. Dissolve magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in deionized water to prepare a mixed salt solution. Pour sodium carbonate into sodium hydroxide solution to prepare an alkaline solution. Mix the mixed salt solution and the alkaline solution together, stir at 80-120 rpm, let stand at 60-65℃ for 24 hours, filter and wash until neutral, and dry at 80℃ for 12 hours to obtain magnesium aluminum hydrotalcite. b. Place the magnesium-aluminum hydrotalcite in a muffle furnace, heat it to 500℃ at a rate of 5℃ / min, calcine it at a constant temperature for 5 hours, and then cool it naturally to obtain a magnesium-aluminum mixed oxide.

[0025] A method for preparing a solid-liquid phase O-alkylation reaction catalyst: S1. Prepare magnesium-aluminum mixed oxide according to the above method; S2. The magnesium-aluminum mixed oxide was vacuum dried at 120-125℃ for 2 hours, then placed in anhydrous toluene and ultrasonically dispersed. Under nitrogen atmosphere, 3-glycidyl etheroxypropyltrimethoxysilane and methylsilane were added and refluxed at 110-115℃ for 24 hours. After centrifugation at 6000-7000 rpm for 5-10 minutes, the mixture was washed with toluene and ethanol in sequence, and dried to obtain silanized magnesium-aluminum mixed oxide. S3. Dissolve chitosan in glacial acetic acid solution and stir until completely dissolved. Then add dilute sodium hydroxide to adjust the pH to 5.0-6.0. S4. Disperse the silanized magnesium aluminum mixed oxide in deionized water using ultrasonication, then add chitosan solution, stir at 20-25℃ for 24 hours, centrifuge at 5000-6000 rpm for 5-10 minutes to separate the solid, then wash with deionized water 3-5 times, and then wash with ethanol once to obtain chitosan-silanized magnesium aluminum mixed oxide.

[0026] S5. Chitosan-alkylated magnesium aluminum mixed oxide was placed in anhydrous dichloromethane and cooled to 0°C in an ice-water bath. Then, chlorosulfonic acid was slowly added while maintaining the temperature at 0°C throughout the dropwise addition process. The mixture was then stirred for 4 hours, deionized water was added, the solid was separated by centrifugation, washed with deionized water and anhydrous ethanol, and dried in a vacuum environment at 50°C for 1 hour to obtain a solid-liquid phase O-alkylation reaction catalyst. Example 1:

[0027] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation consists of 15 parts magnesium nitrate hexahydrate, 25 parts aluminum nitrate nonahydrate, 10 parts sodium hydroxide solution (sodium hydroxide concentration of 2%), and 5 parts sodium carbonate. Subsequent implementations, unless otherwise specified, are consistent with the magnesium-aluminum mixed oxide formulation of Example 1.

[0028] Preparation method of magnesium-aluminum mixed oxide: a. Dissolve magnesium nitrate hexahydrate and aluminum nitrate nonahydrate in deionized water to prepare a mixed salt solution. Pour sodium carbonate into sodium hydroxide solution to prepare an alkaline solution. Mix the mixed salt solution and the alkaline solution together, stir at 100-110 rpm, let stand at 60-65℃ for 24 hours, filter and wash until neutral, and dry at 80℃ for 12 hours to obtain magnesium aluminum hydrotalcite. b. Place the magnesium-aluminum hydrotalcite in a muffle furnace, heat it to 500℃ at 5℃ / min, calcine it at a constant temperature for 5 hours, and then cool it naturally to obtain a magnesium-aluminum mixed oxide. A method for preparing a solid-liquid phase O-alkylation reaction catalyst: S1. Prepare magnesium-aluminum mixed oxide according to the above method; S2. The magnesium-aluminum mixed oxide was vacuum dried at 120-125℃ for 2 hours, then placed in anhydrous toluene and ultrasonically dispersed. Under nitrogen atmosphere, 3-glycidyl etheroxypropyltrimethoxysilane and methylsilane were added and refluxed at 110-115℃ for 24 hours. After centrifugation at 6500-6800 rpm for 5-10 minutes, the mixture was washed with toluene and ethanol in sequence, and dried to obtain silanized magnesium-aluminum mixed oxide. S3. Dissolve chitosan in glacial acetic acid solution and stir until completely dissolved. Then add dilute sodium hydroxide to adjust the pH to 5.0-6.0. S4. Disperse the silanized magnesium aluminum mixed oxide in deionized water using ultrasonication, then add chitosan solution, stir at 20-25℃ for 24 hours, centrifuge at 5500-6000 rpm for 5-10 minutes to separate the solid, then wash with deionized water 3-5 times, and then wash with ethanol once to obtain chitosan-silanized magnesium aluminum mixed oxide.

[0029] S5. Chitosan-alkylated magnesium aluminum mixed oxide was placed in anhydrous dichloromethane and cooled to 0°C in an ice-water bath. Then, chlorosulfonic acid was slowly added, maintaining the temperature at 0°C throughout the dropwise addition process. The mixture was stirred for 4 hours, then deionized water was added. The solid was separated by centrifugation, washed with deionized water, washed with anhydrous ethanol, and dried under vacuum at 50°C for 1 hour to obtain a solid-liquid phase O-alkylation reaction catalyst. Unless otherwise specified, the preparation methods in subsequent examples are the same as in Example 1. Example 2:

[0030] Catalyst formulation: 10 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 3:

[0031] Catalyst formulation: 14 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 4:

[0032] Catalyst formulation: 18 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 5:

[0033] Catalyst formulation: 20 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 6:

[0034] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 4 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 7:

[0035] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 6 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 8:

[0036] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 10 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 9:

[0037] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1 part methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 10:

[0038] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.2 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 11:

[0039] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.8 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 12:

[0040] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 2 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 13:

[0041] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 1 part chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 14:

[0042] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 2.5 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 15:

[0043] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3.5 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 16:

[0044] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 5 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 17:

[0045] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 7 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 18:

[0046] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 9 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 19:

[0047] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 15 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation is consistent with the magnesium-aluminum mixed oxide formulation of Example 1; The preparation method is the same as in Example 1. Example 20:

[0048] The catalyst formulation is the same as in Example 1; Formula for magnesium-aluminum mixed oxide: 12 parts magnesium nitrate hexahydrate, 30 parts aluminum nitrate nonahydrate, 13 parts sodium hydroxide solution, and 4.2 parts sodium carbonate; The preparation method is the same as in Example 1. Example 21:

[0049] The catalyst formulation is the same as in Example 1; Formula for magnesium-aluminum mixed oxide: 15 parts magnesium nitrate hexahydrate, 32 parts aluminum nitrate nonahydrate, 15 parts sodium hydroxide solution, and 4.5 parts sodium carbonate; The preparation method is the same as in Example 1. Example 22:

[0050] The catalyst formulation is the same as in Example 1; Formula for magnesium-aluminum mixed oxide: 18 parts magnesium nitrate hexahydrate, 30 parts aluminum nitrate nonahydrate, 15 parts sodium hydroxide solution, and 4.2 parts sodium carbonate; The preparation method is the same as in Example 1. Comparative Example 1:

[0051] Catalyst formulation: 16 parts silica, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; This comparative example uses silica as a substrate to remove the alkaline catalytic center of the magnesium-aluminum mixed oxide. Comparative Example 2:

[0052] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, and 3 parts chitosan; Magnesium-aluminum mixed oxide formulation: 15 parts magnesium nitrate hexahydrate, 25 parts aluminum nitrate nonahydrate, 10 parts sodium hydroxide solution (sodium hydroxide concentration is 2%), and 5 parts sodium carbonate. This comparative example omits chlorosulfonic acid to avoid introducing acidic groups, retaining only the basic center. Comparative Example 3:

[0053] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation consists of 15 parts magnesium nitrate hexahydrate, 25 parts aluminum nitrate nonahydrate, 10 parts sodium hydroxide solution (2% sodium hydroxide concentration), and 5 parts sodium carbonate. This comparative example does not include 3-glycidyl etheroxypropyltrimethoxysilane or methylsilane; it is simply a mixture of magnesium-aluminum mixed oxide and sulfonated chitosan. Comparative Example 4:

[0054] Catalyst formulation: 16 parts magnesium-aluminum mixed oxide, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 3 parts chitosan, and 11 parts chlorosulfonic acid; The magnesium-aluminum mixed oxide formulation consists of 15 parts magnesium nitrate hexahydrate, 25 parts aluminum nitrate nonahydrate, 10 parts sodium hydroxide solution (2% sodium hydroxide concentration), and 5 parts sodium carbonate. This comparative example does not include methylsilane, thus lacking its hydrophobic effect. Comparative Example 5:

[0055] Catalyst formulation: 16 parts magnesium aluminum hydrotalcite, 7 parts 3-glycidyl etheroxypropyltrimethoxysilane, 1.5 parts methylsilane, 3 parts chitosan, and 11 parts chlorosulfonic acid. This comparative example uses magnesium-aluminum hydrotalcite instead of magnesium-aluminum mixed oxide.

[0056] Catalyst performance tests were conducted on Examples 1-21 above: Bisphenol A (2,2-bis(4-hydroxyphenyl)propane), which is solid at room temperature, was reacted with propylene oxide, which is liquid at room temperature, to synthesize bisphenol A polyoxypropylene ether. The reaction mixture consisted of 8 mmol of solid phase, 32 mmol of liquid phase, 0.2 g of catalyst, and 10 mL of toluene solvent. Bisphenol A (8 mmol), the catalyst (0.2 g), and toluene (10 mL) were added to a 1 L stainless steel stirred reactor. Nitrogen gas was introduced to replace the air, and stirring was started (135 rpm). The reactor was evacuated to -0.095 mPa and heated to 90 °C. Propylene oxide (32 mmol) was slowly added dropwise, maintaining the reactor pressure ≤0.25 mPa and the temperature ≤125 °C. The reaction was continued with stirring for 4 hours. During the reaction, the solid-phase bisphenol A gradually dissolved and was consumed, and the product, bisphenol A polyoxypropylene ether, was formed and dissolved in toluene.

[0057] Table 1. Experimental results of Examples 1-22.

[0058]

[0059] As shown in the table above, the catalyst of this invention exhibits excellent performance in terms of raw material conversion rate, product yield, and catalyst stability. Examples 1-5 illustrate the effect of the amount of magnesium-aluminum mixed oxide added on catalyst performance. With the addition of magnesium-aluminum mixed oxide, the raw material conversion rate initially increases and then decreases, the product yield initially increases and then decreases, and the catalyst activity content initially increases and then decreases. The optimal addition range is 16-18 parts. This is because the magnesium-aluminum mixed oxide mainly provides alkaline catalytic centers in this catalyst. If the content is low, the density of alkaline catalytic sites decreases, leading to a reduction in the catalytic effect. The magnesium-aluminum mixed oxide also serves as a framework structure, providing a better specific surface area and pore structure, which allows the silane coupling agent to better anchor chitosan, making it more uniformly distributed and less prone to detachment, thus improving catalyst stability. If the content is too high, it will lead to an excessively high density of alkaline catalytic sites, resulting in a decrease in acidic catalytic activity. In addition, it will exacerbate catalytic side reactions, reduce the selectivity of the target product, decrease the conversion rate, and excessive inorganic substrate will also lead to smaller pore structures, lower mass transfer efficiency, and decreased stability.

[0060] Examples 1 and 6-8 illustrate the effect of the amount of 3-glycidyl etheroxypropyltrimethoxysilane added on catalyst performance. As the amount added increases, the conversion rate of the raw materials initially increases and then decreases, the product yield initially increases and then decreases, and the catalyst activity content initially increases and then decreases. 3-glycidyl etheroxypropyltrimethoxysilane primarily acts as a linker. If its content decreases, chitosan is not fully loaded onto the magnesium-aluminum mixed oxide, leading to a reduction in acidic catalytic sites and thus affecting the conversion rate. Simultaneously, incomplete chitosan coverage results in uneven catalytic activity and localized deactivation. Insufficient content leads to unstable chitosan loading, resulting in a significant decrease in catalyst stability with continuous use. Excessive addition can cause pore blockage in the catalyst, hindering mass transfer and covering catalytic active sites.

[0061] Examples 1 and 9-12 illustrate the effect of methylsilane addition on catalyst performance. As the addition amount increases, feed conversion initially increases and then decreases, product yield initially increases and then decreases, and catalyst activity initially increases and then decreases. Except for the significant effect on product yield, the differences between the other two are minimal. Methylsilane does not affect the formation of acid-base sites and mainly plays an auxiliary role in the reaction. When the addition amount is small, although some hydrophobic methyl groups are introduced, they cannot completely form continuous and uniform hydrophobic microdomains on the catalyst surface. This results in insufficient product detachment rate after formation, leading to secondary or side reactions and affecting catalyst activity. Conversely, excessive addition leads to over-hydrophobicity, adsorption of feedstock, blockage of pores and catalytic sites, and a deterioration in catalytic effect.

[0062] Examples 1 and 13-16 illustrate the effect of chitosan addition on catalyst performance. With increasing addition, feed conversion initially increases and then decreases, product conversion initially increases and then decreases, and catalyst activity initially increases and then decreases. Chitosan provides acidic catalytic sites, with sulfonic acid groups linked to the chitosan molecule. Low chitosan addition leads to a low density of introduced sulfonic acid groups, limiting the entire catalytic process and reducing alkane activation. While low chitosan content results in a higher anchoring rate, insufficient acidic catalytic site density restricts alkane activation, significantly reducing conversion. Excessive chitosan content leads to over-coating of the pores by the organic layer, shielding the alkaline catalytic center. Excessive physical entanglement also affects mass transfer. Furthermore, insufficient silane coupling agent grafting points cause chitosan to easily detach, reducing stability. 3-Carboxyglycerol etheroxypropyltrimethoxysilane lacks sufficient linkage points, making chitosan prone to detachment during the reaction, resulting in poor stability.

[0063] Examples 1 and 17-19 illustrate the effect of chlorosulfonic acid addition on catalyst performance. Similarly, as the addition amount increases, feed conversion initially increases and then decreases, product conversion initially increases and then decreases, and catalyst activity initially increases and then decreases. Insufficient chlorosulfonic acid leads to incomplete sulfonation, resulting in a lower density of acidic catalytic sites, limited alkane activation, and poor catalytic effect. Excessive chlorosulfonic acid causes partial degradation of chitosan, decreased stability, and excessive hydrophilicity, which still affects the pore structure. Over-sulfonation can also lead to localized side reactions, resulting in lower catalyst activity.

[0064] Examples 1 and 20-22 illustrate the effect of changes in the formulation of the magnesium-aluminum mixed oxide of the present invention on catalyst performance; with changes in its formulation, the performance of the catalyst does not change significantly, and the catalytic effect is good within the formulation range of the magnesium-aluminum mixed oxide of the present invention.

[0065] Table 2. Experimental results of Example 1 and Comparative Examples 1-5.

[0066]

[0067] The above results show that the catalyst of the present invention possesses both acid and basic sites, neither of which can be omitted. Examples 1 and Comparative Examples 1-2 demonstrate that the absence of either acidic or basic sites completely eliminates the acid-base synergistic effect of the catalyst, rendering it a monofunctional catalyst with a significant decrease in catalytic efficiency. Comparative Example 3 and Example 1 show that the absence of silane coupling agents and hydrophobic additives, while still possessing active sites, significantly worsens dispersibility and interfacial structure. While single-reaction activity remains high, stability deteriorates because the chitosan loading method becomes physical adsorption, making it prone to detachment and aggregation, which also affects the catalytic active sites. Comparative Example 4 and the examples show that the absence of hydrophobic additives leads to decreased product selectivity, disappearance of hydrophobic microregions, and a relatively small impact on feed conversion rate, but increases the probability of side reactions and decreases product yield. Furthermore, the catalyst's resistance to carbon deposition and water absorption is weakened, and its stability slightly decreases. As can be seen from Example 1 and Comparative Example 5, the magnesium-aluminum mixed oxide catalyst of the present invention is more effective than ordinary magnesium-aluminum hydrotalcite because the magnesium-aluminum mixed oxide of the present invention can provide sufficiently strong base centers and a stable framework to support efficient acid-base synergistic catalysis.

[0068] The above results show that the catalyst of the present invention has both acid and base catalytic activity, improves the activity of the reaction substrate, is easy to separate and recover after the reaction, and has high stability and long lifespan, making it suitable for solid-liquid phase O-alkylation reactions.

[0069] It should be noted that the above embodiments and comparative examples are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the present invention.

Claims

1. A solid-liquid phase O-alkylation reaction catalyst, characterized in that, The catalyst is composed of an organic compound, a metal oxide, and excipients; the organic compound is sulfonated chitosan, the metal oxide is a magnesium-aluminum mixed oxide, and the excipients are anhydrous toluene, anhydrous ethanol, deionized water, glacial acetic acid solution, sodium hydroxide solution, and anhydrous dichloromethane.

2. The solid-liquid phase O-alkylation reaction catalyst according to claim 1, characterized in that, The catalyst is prepared by weight of 10-20 parts magnesium-aluminum mixed oxide, 4-10 parts silane coupling agent, 1-5 parts chitosan, 7-15 parts chlorosulfonic acid, and 1-2 parts methylsilane.

3. A solid-liquid phase O-alkylation reaction catalyst according to claims 1-2, characterized in that, The magnesium-aluminum mixed oxide is prepared from 10-20 parts of magnesium nitrate hexahydrate, 20-40 parts of aluminum nitrate nonahydrate, 8-16 parts of sodium hydroxide solution, and 4-10 parts of sodium carbonate.

4. A solid-liquid phase O-alkylation reaction catalyst according to claims 1-2, characterized in that, The silane coupling agent is 3-glycidyl etheroxypropyltrimethoxysilane, and the particle size of the chitosan is 80-100 mesh.

5. The solid-liquid phase O-alkylation reaction catalyst according to claim 1, characterized in that, The concentration of the glacial acetic acid solution is 1%, and the concentration of the sodium hydroxide solution is 1-2%.

6. A method for preparing a solid-liquid phase O-alkylation reaction catalyst, characterized in that, The preparation of the solid-liquid phase O-alkylation reaction catalyst according to claims 1-5 includes the following steps: S1. Preparation of magnesium-aluminum mixed oxide; S2. The magnesium-aluminum mixed oxide was vacuum dried, then placed in anhydrous toluene and ultrasonically dispersed. Under nitrogen atmosphere, 3-glycidyl etheroxypropyltrimethoxysilane and methylsilane were added and refluxed. Then, the mixture was centrifuged, washed with toluene and ethanol in sequence, and dried to obtain silanized magnesium-aluminum mixed oxide. S3. Dissolve chitosan in glacial acetic acid solution and stir until completely dissolved. Then add dilute sodium hydroxide to adjust the pH to 5.0-6.

0. S4. The silanized magnesium aluminum mixed oxide is ultrasonically dispersed in deionized water, then chitosan solution is added, stirred, centrifuged to obtain solid, washed with deionized water 3-5 times, washed with ethanol once, and vacuum dried to obtain chitosan-alkylated magnesium aluminum mixed oxide. S5. Chitosan-alkylated magnesium aluminum mixed oxide was placed in anhydrous dichloromethane and cooled in an ice-water bath. Then, chlorosulfonic acid was slowly added. After the addition was complete, the mixture was stirred for 4 hours. Then, deionized water was added, the solid was separated by centrifugation, washed with deionized water, washed with anhydrous ethanol, and dried under vacuum to obtain the final product, the O-alkylation reaction catalyst.

7. The preparation method according to claim 6, characterized in that, The preparation of magnesium-aluminum mixed oxide by S1 includes the following steps: Magnesium nitrate hexahydrate and aluminum nitrate nonahydrate were dissolved in deionized water to prepare a mixed salt solution. Sodium carbonate was poured into sodium hydroxide solution to prepare an alkaline solution. The mixed salt solution and the alkaline solution were mixed together, stirred at 80-120 rpm, and allowed to stand at 60-65℃ for 24 hours. The mixture was then filtered, washed until neutral, and dried at 80℃ for 12 hours to obtain magnesium aluminum hydrotalcite. Magnesium-aluminum hydrotalcite was placed in a muffle furnace and heated to 500℃ at a rate of 5℃ / min. It was then calcined at this constant temperature for 5 hours and allowed to cool naturally to obtain a magnesium-aluminum mixed oxide.

8. The preparation method according to claim 6, characterized in that, The vacuum drying temperature in S2 is 120-125℃ for 2 hours; the reflux reaction temperature is 110-115℃ for 24 hours; the centrifugation speed is 6000-7000 rpm, the centrifugation time is 5-10 minutes, and the drying temperature is 60℃.

9. The preparation method according to claim 6, characterized in that, In step S4, the stirring temperature is 20-25℃, the stirring time is 24h, the centrifugation speed is 5000-6000rpm, the centrifugation time is 5-10min, and the vacuum drying is carried out at 50℃.

10. The preparation method according to claim 6, characterized in that, The ice-water bath in S5 is cooled to 0°C; the entire dropping process is maintained at 0°C; the centrifugation speed is 4000-5000 rpm, and the centrifugation time is 5-10 min; the vacuum drying temperature is 50°C, and the drying time is 1 h.

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