Acidic resin catalysts, their preparation methods and applications, and a continuous preparation method for isosorbide.

Abstract

This invention relates to bio-based diols, and discloses an acidic resin catalyst, its preparation method and application, as well as a continuous preparation method for isosorbide. The polymer in this acidic resin catalyst comprises a first structural unit derived from styrene with an electron-withdrawing group at the meta position of the benzene ring, a second structural unit derived from divinylbenzene, and a third structural unit derived from an propylene sulfonate compound represented by Formula I; and the benzene rings of the first and second structural units have groups derived from an propylene sulfonate compound represented by Formula I or segments containing the third structural unit. The acidic resin catalyst of this invention exhibits excellent catalytic performance and high-temperature stability in the synthesis reaction of isosorbide. In particular, the combination of this acidic resin catalyst and a solid acid catalyst in the synthesis reaction of isosorbide not only achieves catalytic stability but also features high isosorbide yield and high selectivity, making it very suitable for continuous production.

Description

Technical Field

[0001] This invention relates to bio-based diols, specifically to an acidic resin catalyst, its preparation method and application, and a continuous preparation method for isosorbide. Background Technology

[0002] With the continuous depletion of fossil resources and the resulting environmental pollution, and given the renewable, abundant, highly functionalized, and environmentally friendly characteristics of biomass, the development and utilization of biomass raw materials and derivatives have become a research hotspot in the fields of fine chemicals and new materials. Isosorbide, as an important biomass-based derivative chemical, is a completely non-toxic green diol, widely used not only in pharmaceuticals, surfactants, and plastic additives, but also playing a crucial role in the field of novel polymer materials. For example, isosorbide is an excellent antihypertensive drug and diuretic; it can be used to synthesize surfactants Span and Tween; it can also be used to synthesize novel green plasticizers to replace phthalate ester plasticizers; isosorbide can be used to modify PET to significantly improve its high-temperature properties and impact resistance by replacing ethylene glycol; in polycarbonate new material technology, it is showing promise as an important raw material to replace bisphenol A, which poses health risks, thereby improving the environmentally friendly performance of polycarbonate. Therefore, the synthesis technology of isosorbide has received considerable attention in recent years.

[0003] Currently reported synthetic routes for isosorbide mainly use sorbitol or cellulose as raw materials and solid or liquid acids as catalysts. Liquid acids primarily include concentrated sulfuric acid, benzenesulfonic acid, and ionic liquids; solid acids mainly include molecular sieves, acidic resins, metal oxides, metal phosphates, and heteropoly acids, synthesized via batch processes. While batch processes offer advantages such as low investment and suitability for small-batch production, they suffer from drawbacks such as unstable product quality and difficulty in automating operations, failing to meet the requirements of large-scale industrial production. Considering the performance advantages of isosorbide and its applications in new materials, market demand is likely to increase rapidly; therefore, a continuous process for isosorbide production needs to be developed. Literature reports the use of continuous processes for isosorbide production. US6864378A employs a continuous production method for isosorbide using a liquid acid catalyst, with the resulting product distilling off as an azeotrope with water vapor. CN104788465A describes a continuous production method for isosorbide using a two-stage dehydration process, but it does not mention the type of catalyst used. The product separation requires deacidification and desalting steps. CN204752581A describes a continuous production method for isosorbide, which also requires deacidification and desalting steps during product separation. US6639067A describes a continuous preparation method for isosorbide using an organic solvent as a dehydrating agent. The product and solvent are distilled off, and the product is then separated; the solvent can be recycled. CN103980286A describes a continuous preparation process for isosorbide using a liquid acid as a catalyst. It is evident that the continuous processes described in the literature all use liquid acids, thus requiring neutralization and desalting processes in subsequent separation steps, increasing the number of steps and production costs. In comparison, solid acid dehydration catalysts offer advantages such as relatively simple product separation and catalyst recyclability. However, solid catalysts suffer from limitations in catalyst lifetime and selectivity under high-temperature conditions. Literature reports that in the catalytic dehydration synthesis of isosorbide, solid acid catalysts using strongly acidic resins exhibit good performance in conversion and selectivity, but their lifetime is limited. Especially at reaction temperatures above 120°C, sulfonic acid groups easily detach, significantly reducing acidity and failing to meet the requirements of continuous isosorbide production processes. This results in higher production costs and unstable product quality, thus limiting their industrial application. Furthermore, since the raw material hexitol contains multiple active hydroxyl groups, multiple dehydration reaction pathways exist under catalysis, potentially producing 1,4-dehydration products, 1,5-dehydration products, and 2,5-dehydration products. Only the 1,4-dehydration product can undergo a secondary dehydration reaction to generate isosorbide. Therefore, the key is to employ innovative catalyst systems to improve the selectivity of the 1,4-dehydration product and suppress the formation of byproducts. Currently, the selectivity of the catalyst can only reach 70%, resulting in limited isosorbide yield and high unit production cost, which has prevented large-scale commercial application. Summary of the Invention

[0004] To address the limitations of existing strong acid resin catalysts, which have limited lifespans and cannot meet the requirements of continuous isosorbide production processes, leading to high production costs and unstable product quality, as well as the poor selectivity of conventional catalysts for isosorbide yield, resulting in low isosorbide yields and an inability to achieve both high catalytic stability and high isosorbide yield simultaneously, this invention provides an acid resin catalyst, its preparation method, its application, and a continuous preparation method for isosorbide. The acid resin catalyst of this invention exhibits excellent catalytic performance and high-temperature stability in the isosorbide synthesis reaction. In particular, the combination of this acid resin catalyst and a solid acid catalyst in the isosorbide synthesis reaction not only achieves catalytic stability but also provides high isosorbide yield and high selectivity, making it highly suitable for continuous production. Therefore, it reduces production costs and improves product quality stability.

[0005] A first aspect of the present invention is to provide an acidic resin catalyst, wherein the polymer in the acidic resin catalyst comprises a first structural unit derived from styrene having an electron-withdrawing group at the meta position of a benzene ring, a second structural unit derived from divinylbenzene, and a third structural unit derived from an propylene sulfonic acid compound represented by Formula I.

[0006] R1, R2, and R3 are each hydrogen or a C1-C2 alkyl group (i.e., methyl or ethyl), and M is H or a metal element; and the benzene rings of the first and second structural units have groups derived from propylene sulfonic acid compounds shown in Formula I or segments containing the third structural unit; and M in the polymer is H or a metal element.

[0007] In a preferred embodiment of the present invention, the polymer in the acidic resin catalyst contains structural units shown in Formula 2, Formula 3, and Formula 4.

[0008]

[0009] Y1 and Y2 are each a group derived from the compound shown in Formula I or a segment of the corresponding structural unit of the compound shown in Formula I; X is an electron-withdrawing group; R1, R2, and R3 are each hydrogen or a C1-C2 alkyl group. In this preferred embodiment, the acidic resin catalyst exhibits superior catalytic performance and high-temperature stability in the synthesis reaction of isosorbide. In particular, the combination of this acidic resin catalyst and a solid acid catalyst in the synthesis reaction of isosorbide demonstrates higher catalytic stability, as well as higher isosorbide yield and selectivity.

[0010] According to the present invention, the electron-withdrawing group can be selected from a wide range. In a preferred embodiment of the present invention, the electron-withdrawing group is at least one of a halogen atom, a nitroso group, and an acetoxy group.

[0011] According to the present invention, the content of each structural unit can be selected within a wide range. In a preferred embodiment of the present invention, based on the total weight of the polymer of 100 wt%, the content of the first structural unit is 1-50 wt%; the content of the second structural unit is 30-90 wt%; and the content of the third structural unit is 1-50 wt%. In this preferred embodiment, compared with acidic resin catalysts whose content of each structural unit is not within the above range, the acidic resin catalyst obtained by this preferred embodiment exhibits further superior catalytic performance and high-temperature stability in the synthesis reaction of isosorbide. In particular, the combination of this acidic resin catalyst and the solid acid catalyst in the synthesis reaction of isosorbide has further higher catalytic stability, and also has the advantages of further higher isosorbide yield and further higher selectivity.

[0012] Through further research, the inventors of this invention discovered that, more preferably, the content of each structural unit is as follows: based on a total weight of 100 wt% of the polymer, the content of the first structural unit is 20-40 wt%, for example, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, and any two values ​​or any range of any two values; the content of the second structural unit is 40-60 wt%, for example, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, and any two values ​​or any range of any two values; the content of the third structural unit is 20-40 wt%, for example, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, and any two values ​​or any range of any two values. In this preferred embodiment, compared to acidic resin catalysts whose content of each structural unit is not within the above-mentioned preferred range, the acidic resin catalyst obtained by this preferred embodiment exhibits even better catalytic performance and high-temperature stability in the synthesis reaction of isosorbide. In particular, when the acidic resin catalyst and the solid acid catalyst are combined in the synthesis reaction of isosorbide, the catalytic stability is even higher, and the isosorbide yield and selectivity are even higher.

[0013] In a preferred embodiment of the present invention, the specific surface area of ​​the acidic resin catalyst is 200-500 m². 2 ·g -1 .

[0014] In a preferred embodiment of the present invention, the pore volume of the acidic resin catalyst is 0.2-0.8 cm³.3 ·g -1 .

[0015] In a preferred embodiment of the present invention, the pore size of the acidic resin catalyst is 1-10 nm.

[0016] In a preferred embodiment of the present invention, the acid content of the acidic resin catalyst is 3-8 mmol·g. -1 .

[0017] In a preferred embodiment of the present invention, the number-average molecular weight of the polymer is 10,000-100,000.

[0018] A second aspect of the present invention is to provide a method for preparing the acidic resin catalyst described in the first aspect, comprising the following steps:

[0019] In the presence of a dispersant and an initiator, divinylbenzene, styrene with electron-withdrawing groups at the meta-position of the benzene ring, and propylene sulfonic acid compounds of Formula I are copolymerized to obtain resin matrix I; or,

[0020] In the presence of a dispersant and an initiator, divinylbenzene and styrene with electron-withdrawing groups at the meta position of the benzene ring are polymerized to obtain a resin pre-matrix. The resin pre-matrix is ​​then reacted with an propylene sulfonic acid compound as shown in Formula I to obtain resin matrix II.

[0021] Acidic resin catalysts are obtained by acidifying resin matrix one and / or resin matrix two.

[0022] R1, R2, and R3 are each hydrogen or C1-C2 alkyl groups, and M is H or a metal element.

[0023] In a preferred embodiment of the present invention, the preparation method includes the following steps:

[0024] (1) Method 1: A solution containing a dispersant is mixed with a mixture containing divinylbenzene, styrene with electron-withdrawing groups at the meta-position of the benzene ring, propylene sulfonic acid compounds, and an initiator, and a polymerization reaction is carried out to obtain resin matrix one. Resin matrix one is then mixed with an organic solvent containing a pore-expanding agent to obtain a mixture containing resin matrix one; or,

[0025] (1) Method 2: Mix a solution containing a dispersant with a mixture containing divinylbenzene, styrene with electron-withdrawing groups at the meta position of the benzene ring, and an initiator to carry out a polymerization reaction to obtain a resin pre-matrix. Then, react the resin pre-matrix with an propylene sulfonic acid compound in an organic solvent containing a pore-expanding agent to obtain a mixture containing resin matrix 2.

[0026] (2) The mixture of method one and / or method two corresponding to step (1) is contacted with a strong acid for acidification, washed and dried to obtain the acidic resin catalyst.

[0027] According to the present invention, the dispersant can be selected from a wide range. In a preferred embodiment of the present invention, the dispersant is selected from at least one of polyvinyl alcohol and hydroxyethyl cellulose; preferably, it is polyvinyl alcohol with a number average molecular weight of 150,000-250,000.

[0028] According to the present invention, the initiator can be selected from a wide range. In a preferred embodiment of the present invention, the initiator is an azo compound and / or a peroxide, preferably at least one of benzoyl peroxide, phenylacetyl peroxide, potassium peroxide and azobisisobutyronitrile.

[0029] According to the present invention, the pore-expanding agent can be selected from a wide range. In a preferred embodiment of the present invention, the pore-expanding agent is at least one selected from toluene, dichloromethane, dichloroethane and n-heptane.

[0030] According to the present invention, the amount of each raw material can be selected within a wide range. In a preferred embodiment of the present invention, the amount of initiator is 0.2-6 parts by mass, preferably 0.5-4 parts, relative to all monomers with a total mass of 100 parts; and the amount of dispersant is 1-10 parts, preferably 4-6 parts.

[0031] According to the present invention, the amount of pore expander can be selected within a wide range. In a preferred embodiment of the present invention, the amount of pore expander is 2-30 parts by weight relative to 100 parts by weight of resin matrix or resin prematrix.

[0032] According to the present invention, the conditions for polymerization reaction can be selected within a wide range. In a preferred embodiment of the present invention, the conditions for polymerization reaction corresponding to Method 1 and Method 2 in step (1) are respectively: temperature of 60-150℃ and / or time of 70-140h.

[0033] According to the present invention, the conditions for mixing the resin matrix with the organic solvent containing the pore-expanding agent in step (1) can be selected within a wide range. In a preferred embodiment of the present invention, the conditions for mixing the resin matrix with the organic solvent containing the pore-expanding agent in step (1) include: raising the temperature of the mixture to 30-100°C at a rate of 1-10°C / min.

[0034] According to the present invention, the conditions for reacting the resin pre-matrix with the propylene sulfonic acid compound in an organic solvent containing a pore-expanding agent in step (1) can be selected within a wide range. In a preferred embodiment of the present invention, the conditions for reacting the resin pre-matrix with the propylene sulfonic acid compound in an organic solvent containing a pore-expanding agent in step (1) include: raising the temperature of the mixed system to 30-100°C at a rate of 1-10°C / min.

[0035] According to the present invention, the acidification conditions in step (2) can be selected within a wide range. In a preferred embodiment of the present invention, the acidification conditions in step (2) include: a temperature of 30-100°C and / or a time of 5-20h.

[0036] According to the present invention, the type of strong acid can be selected from a wide range. In a preferred embodiment of the present invention, the strong acid is selected from at least one of concentrated sulfuric acid, chlorosulfonic acid, fuming sulfuric acid, and methanesulfonic acid.

[0037] As an example, the acidic resin catalyst of the present invention can be prepared in the following manner:

[0038] First, a dispersant and water are added to the reactor, stirring is started, and the mixture is slowly heated until dissolved to form a continuous phase. Then, a certain proportion of styrene and divinylbenzene with electron-withdrawing groups are mixed, and a certain amount of initiator is added. This mixture is then added to the continuous phase, stirred, and heated for 5-10 hours to ensure complete monomer polymerization. The mixture is then cooled to room temperature, filtered, washed, dried, and sieved. The self-made macroporous resin is weighed and added to the reactor, along with a small amount of solvent, pore-expanding agent, and sulfonic acid-containing monomer. The temperature is slowly increased, and then a strong acid is added dropwise. After the addition is complete, the reaction continues for 7-12 hours. After the reaction is complete, the mixture is cooled to room temperature, filtered, and the product is then soaked in solvent, washed, filtered, and dried to constant weight. In other words, using substituted styrene, divinylbenzene, and sulfonic acid-containing monomers as raw materials, organic peroxides as initiators, and dispersants and pore-expanding agents, macroporous particulate resin is synthesized via suspension copolymerization. Further, carbon chains of sulfonic acid groups are attached to the benzene ring to prepare the acidic resin catalyst of this invention.

[0039] A third aspect of the present invention is to provide the application of the acidic resin catalyst described in the first aspect or the acidic resin catalyst prepared by the preparation method described in the second aspect in the preparation of isosorbide. Preferably, the acidic resin catalyst of the present invention is not limited to being used alone as a catalyst for the preparation of isosorbide, or the acidic resin catalyst of the present invention may be combined with other types of catalysts as a catalyst for the preparation of isosorbide.

[0040] A fourth aspect of the present invention is to provide a continuous method for preparing isosorbide, comprising the following steps:

[0041] 1) Hexitol is contacted with a solid acid catalyst to carry out a primary dehydration reaction, yielding a primary dehydration reaction mixture;

[0042] 2) Remove the solid acid catalyst from the primary dehydration reaction mixture, and then contact the resulting mixture with an acidic resin catalyst to carry out a secondary dehydration reaction to obtain a reaction product containing isosorbide.

[0043] The acidic resin catalyst is the acidic resin catalyst described in the first aspect and / or the acidic resin catalyst prepared by the preparation method described in the second aspect.

[0044] This invention discloses a continuous preparation method for isosorbide, using hexitol as a raw material and employing a highly selective catalyst. Suitable for continuous processes, the method includes a feeding unit, a reaction unit, and a product purification unit. The reaction unit comprises two reactors: a primary reactor prepares the 1,4-dehydrated product, and a secondary reactor prepares isosorbide. Different catalysts are used in the two reactors depending on the reaction objective. The primary reactor uses a solid acid catalyst suitable for the formation of 1,4-dehydrated sorbitol, while the secondary reactor uses a self-made catalyst suitable for isosorbide formation, thus achieving continuous and efficient isosorbide production. This invention utilizes a specific acidic resin catalyst combined with a solid acid catalyst and a specific two-stage dehydration reaction to obtain high-yield and highly selective isosorbide. Furthermore, the entire preparation method exhibits catalytic stability and enables continuous production, possessing significant potential for widespread application.

[0045] According to the present invention, the hexitol can be selected from a wide range. In a preferred embodiment of the present invention, the hexitol is selected from sorbitol and / or 1,4-anhydrosorbitol, and / or the hexitol is derived from solid hexitol and / or a solution of hexitol.

[0046] According to the present invention, the solid acid catalyst can be selected from a wide range. In a preferred embodiment of the present invention, the solid acid catalyst is selected from at least one of molecular sieves, acidic resins, metal phosphates, Lewis acids, and heteropolyacids, preferably at least one of heteropolyacids and acidic resins; more preferably heteropolyacids, and even more preferably phosphotungstic acid solid acid catalysts. The inventors of the present invention have discovered that when phosphotungstic acid solid acid catalysts are used in the primary dehydration reaction, and the acidic resin catalyst of the present invention is used in the secondary dehydration reaction, the method for preparing isosorbide unexpectedly outperforms other types of solid acid catalysts in the continuous preparation method of the present invention. This may be because the phosphotungstic acid solid acid catalyst and the acidic resin catalyst of the present invention have a better synergistic effect in the two-stage dehydration reaction.

[0047] According to the present invention, the mass ratio of the solid acid catalyst to hexitol can be selected within a wide range. In a preferred embodiment of the present invention, in the first-stage dehydration reaction, the mass ratio of the solid acid catalyst to hexitol is (1-10):100, preferably (3-5):100.

[0048] In a preferred embodiment of the present invention, the selectivity of 1,4-dehydrated sorbitol is controlled to be above 80% in the primary dehydration reaction, and then the secondary dehydration reaction is started. In this preferred embodiment, isosorbitol has a higher yield and selectivity.

[0049] According to the present invention, the mass ratio of the acidic resin catalyst to hexitol can be selected within a wide range. In a preferred embodiment of the present invention, in the secondary dehydration reaction, the mass ratio of the acidic resin catalyst to hexitol is (1-10):100, preferably (2-4):100.

[0050] In a preferred embodiment of the present invention, the selectivity of isosorbide is controlled to be above 80% in the secondary dehydration reaction.

[0051] According to the present invention, the conditions in step 1) can be selected within a wide range. In a preferred embodiment of the present invention, the conditions in step 1) include: a reaction temperature of 80-130°C, and / or a residence time of 3-7 h, and / or a reaction pressure of 0-1 atm.

[0052] According to the present invention, the conditions in step 2) can be selected within a wide range. In a preferred embodiment of the present invention, the conditions in step 2) include: a reaction temperature of 120-160°C, and / or a residence time of 5-9 h, and / or a reaction pressure of 0-1 atm.

[0053] In a preferred embodiment of the present invention, the water generated in the primary dehydration reaction is discharged through the top of the reactor during the reaction process, and / or the primary dehydration reaction mixture is dehydrated before entering the secondary dehydration reaction. Preferably, the dehydration treatment is carried out by using a dehydration tower.

[0054] In a preferred embodiment of the present invention, the continuous preparation method further includes separating and purifying the obtained reaction product containing isosorbide after a secondary dehydration reaction to obtain purified isosorbide.

[0055] According to the present invention, the purification and separation method can employ conventional separation and purification methods in the art. In a preferred embodiment of the present invention, the purification and separation method is distillation and / or crystallization. For example, distillation can be carried out at a distillation temperature of 160°C and a vacuum degree of 5 mba, followed by crystallization in a mixed solvent of isopropanol and n-hexane, preferably with a mass ratio of isopropanol to n-hexane of (10-20):1.

[0056] As an example, the continuous preparation method of isosorbide of the present invention can be implemented in the following manner:

[0057] The reactants are solid or isosorbide solution. The reactants are added to a preheating tower and heated until they have good fluidity. Then, they enter a first stirred reactor containing a solid acid catalyst. The reaction temperature is between 80-130℃, the residence time is between 3-7 hours, and the reaction pressure is between 0-1 atm. The amount of solid acid catalyst added is between 1-10 wt% of the reactants. After a certain reaction time, the product is filtered through a valve filter in the reactor and then enters a dehydration tower, while reactants are replenished at a certain rate. The filtered product is dehydrated in the dehydration tower and then enters a second stirred reactor for further dehydration. The second reactor contains a self-made acidic resin catalyst. The reaction temperature is between 120-160℃, the residence time is between 5-9 hours, and the reaction pressure is between 0-1 atm. The amount of catalyst added is between 1-10 wt% of the reactants. After the reaction has proceeded for a certain period of time, the reaction solution enters the separation system. Through filtration, distillation, and crystallization, the product is separated, purified, and dried. Testing shows that the product has very high purity, suitable for chemical, pharmaceutical, and polymerization applications. Part of the separated liquid is recycled. The catalyst undergoes post-treatment and is also recycled, enabling continuous operation of the entire system.

[0058] As can be seen from the above description of the present invention, the present invention has the following advantages:

[0059] (1) The acidic resin catalyst of the present invention exhibits excellent catalytic performance and high temperature stability in the synthesis reaction of isosorbide. In particular, the combination of the acidic resin catalyst and the solid acid catalyst in the synthesis reaction of isosorbide not only achieves catalytic stability, but also has the characteristics of high isosorbide yield and high selectivity, which is very suitable for continuous production, thus reducing production costs and improving product quality stability.

[0060] This invention uses substituted styrene, divinylbenzene, and monomers containing sulfonic acid groups (as shown in Formula I) as raw materials, organic peroxides as initiators, and dispersants and pore expanders as additives. A macroporous particulate resin is synthesized via suspension copolymerization. Further, carbon chains containing sulfonic acid groups are incorporated into the benzene ring. Then, a self-made resin is used for sulfonation to prepare a high-temperature resistant, strongly acidic resin catalyst. Due to the introduction of electron-withdrawing groups and the incorporation of carbon chains into the molecular structure, the bonding force of the sulfonic acid groups is stronger, improving the thermal stability of the sulfonic acid groups and thus increasing the high-temperature lifetime of the catalyst. Furthermore, post-treatment further enhances the catalyst's pore structure and specific surface area, improving the selectivity of the dehydration reaction. Therefore, combining this catalyst with a solid acid catalyst in the synthesis of isosorbide exhibits excellent catalytic performance and high-temperature stability, making it suitable for continuous production. This reduces production costs and improves product quality stability. The isosorbide synthesized by this invention can be widely used in new materials, pharmaceuticals, and organic synthesis.

[0061] (2) This invention uses a specific acidic resin catalyst combined with a solid acid catalyst and a specific two-stage dehydration reaction to obtain isosorbide with high yield and high selectivity. Moreover, the entire preparation method is catalytically stable and realizes continuous production, which has extremely high value for promotion and application. Detailed Implementation

[0062] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0063] The parameters of the phosphotungstic acid solid acid catalyst were analytical grade and purchased from Aladdin Reagent Co., Ltd.

[0064] In the following examples, the number average molecular weight of polyvinyl alcohol is 150,000-250,000.

[0065] The method for detecting the acid content in acidic resins is as follows: acid-base neutralization titration.

[0066] The method for detecting the pore volume of acidic resins is: nitrogen adsorption-desorption method;

[0067] The specific surface area of ​​acidic resins is determined by nitrogen adsorption-desorption method.

[0068] Unless otherwise specified, all raw materials used in this invention are commercially available products.

[0069] Catalyst Preparation Example 1

[0070] Weigh 2g of polyvinyl alcohol into a three-necked flask, then add 500mL of water, heat to boiling, and stir until the polyvinyl alcohol is completely dissolved to form a continuous phase. Cool to 65℃. Weigh 30g of meta-substituted chlorostyrene and 60g of divinylbenzene according to the proportions, and weigh 3g of benzoyl peroxide into a beaker and dissolve evenly to form a dispersed phase.

[0071] The dispersed phase was added to a three-necked flask containing the continuous phase, and the mixture was stirred and heated to 90°C for 7 hours to ensure complete monomer reaction. After polymerization was complete, the reaction was stopped. After cooling to room temperature (25°C), the mixture was filtered, washed, dried, sieved, and weighed to obtain the macroporous resin.

[0072] Take 20g of sodium allyl sulfonate, weigh 40g of self-made macroporous resin, add them to the reactor, add 45g of solvent toluene and 8g of pore expander dichloromethane, heat to 65℃ at a rate of 6℃ / h, then add 50g of concentrated sulfuric acid (mass concentration of 98%) dropwise, and react for another 10h after the addition is complete. After the reaction is complete, cool to room temperature, filter and separate, then add isopropanol to soak for 10h, filter, wash the product with deionized water until neutral, filter and dry to constant weight to obtain acidic resin catalyst.

[0073] Catalyst Preparation Example 2

[0074] Weigh 2g of polyvinyl alcohol into a three-necked flask, then add 500mL of water, heat to boiling, and stir until the polyvinyl alcohol is completely dissolved to form a continuous phase. Cool to 65℃. Weigh 30g of meta-substituted chlorinated styrene and 60g of divinylbenzene according to the proportions, and weigh 3g of benzoyl peroxide into a beaker and dissolve evenly to form a dispersed phase. Add the dispersed phase to the three-necked flask containing the continuous phase, stir, and heat to 90℃ for 7 hours to ensure complete monomer reaction. After polymerization is complete, stop the reaction. After cooling to room temperature, filter, wash, dry, sieve, and weigh to obtain the macroporous resin.

[0075] Take 20g of sodium methyl allyl sulfonate, weigh 40g of self-made macroporous resin, add them to the reactor, add 50g of solvent toluene and 10g of pore expander (dichloromethane), heat to 65℃ at a rate of 6℃ / h, then add 50g of concentrated sulfuric acid (mass concentration of 98%) dropwise, and react for another 10h after the addition is complete. After the reaction is complete, cool to room temperature, filter and separate, then add isopropanol to soak for 10h, filter, wash the product with deionized water until neutral, filter and dry to constant weight to obtain acidic resin catalyst.

[0076] Catalyst Preparation Example 3

[0077] Weigh 3g of polyvinyl alcohol into a three-necked flask, then add 500mL of water, heat to boiling, and stir until the polyvinyl alcohol is completely dissolved to form a continuous phase. Cool to 65℃. Weigh 30g of meta-chlorinated styrene, 60g of divinylbenzene, and 40g of sodium allyl sulfonate according to the specified proportions, and weigh 3g of potassium persulfate into a beaker and dissolve them evenly to form a dispersed phase. Add the dispersed phase to the three-necked flask containing the continuous phase, stir, and heat to 90℃ for 7 hours to ensure complete monomer reaction. After polymerization is complete, stop the reaction. After cooling to room temperature, filter, wash, dry, and sieve.

[0078] Weigh 40g of the self-made macroporous resin and add it to the reactor. Add 60g of solvent toluene and 10g of pore expander (dichloromethane). Increase the temperature to 65℃ at a rate of 6℃ / h, and then add 30g of hydrochloric acid (mass concentration of 36%) dropwise. After the addition is complete, react for another 10h. After the reaction is complete, cool to room temperature, filter and separate. Then add isopropanol and soak for 10h. Wash with water and filter. Wash the product with deionized water until neutral, filter and dry to constant weight to obtain the acidic resin catalyst.

[0079] Catalyst Preparation Example 4

[0080] Weigh 3g of polyvinyl alcohol into a three-necked flask, then add 500mL of water, heat to boiling, and stir until the polyvinyl alcohol is completely dissolved to form a continuous phase. Cool to 65℃. Weigh 25g of meta-acetyl-substituted styrene, 50g of divinylbenzene, and 40g of sodium methyl allyl sulfonate according to the proportions, and weigh 3g of potassium persulfate into a beaker and dissolve evenly to form a dispersed phase. Add the dispersed phase to the three-necked flask containing the continuous phase, stir, and heat to 90℃ for 7 hours to ensure complete monomer reaction. After polymerization is complete, stop the reaction. After cooling to room temperature, filter, wash, dry, and sieve.

[0081] Weigh 40g of the self-made macroporous resin and add it to the reactor. Add 50g of solvent toluene and 10g of pore expander (dichloromethane). Increase the temperature to 65℃ at a rate of 5℃ / h. Then add 30g of fuming sulfuric acid (mass concentration of 98%) dropwise. After the addition is complete, react for another 10h. After the reaction is complete, cool to room temperature, filter and separate. Then add isopropanol and soak for 10h. Wash with water and filter. Wash the product with deionized water until neutral. Filter and dry to constant weight to obtain the acidic resin catalyst.

[0082] Catalyst Preparation Comparative Example 1

[0083] Weigh 3g of polyvinyl alcohol into a three-necked flask, then add 500mL of water and heat to boiling. Stir until completely dissolved to form a continuous phase, then cool to 65℃. Weigh 37g of styrene and 63g of divinylbenzene according to the proportions, and weigh 3g of benzoyl peroxide into a beaker and dissolve evenly to form a dispersed phase. Add the dispersed phase to the three-necked flask containing the continuous phase, stir, and heat to 90℃ for 7 hours to ensure complete monomer reaction. After polymerization is complete, stop the reaction. After cooling to room temperature, filter, wash, dry, sieve, and weigh to obtain the macroporous resin.

[0084] Weigh 25g of the self-made macroporous resin and add it to the reactor. Add 22g of xylene solvent and 14g of dichloroethane pore expander. Heat the mixture to 60℃ at a rate of 5℃ / h. Then add 150mL of concentrated sulfuric acid (98% by mass) dropwise. After the addition is complete, react for another 10h. After the reaction is complete, cool to room temperature, filter and separate. Wash the product with deionized water until neutral, filter and dry to constant weight to obtain the acidic resin catalyst.

[0085] Isosorbide Synthesis Example 1

[0086] 100g of 70% sorbitol solution was added to the reactor via a pump, along with a solid acid catalyst (phosphotungstic acid solid acid) accounting for 5% of the sorbitol mass as the primary dehydration catalyst. The mixture was heated to 110°C, stirred, and evacuated to a vacuum of 100mba. Water generated during the reaction was discharged from the top of the reactor through a condenser. After 4 hours of reaction, the selectivity of 1,4-dehydrated sorbitol was found to be 95%. The valve was then opened to feed the reaction raw materials into the reactor at a certain rate. Simultaneously, the reaction liquid was passed through a filter screen at the bottom of the reactor to remove the catalyst, and the resulting filtrate entered the secondary dehydration reactor.

[0087] The secondary reactor was loaded with a self-made acidic resin catalyst (catalyst preparation example 1) accounting for 3% of the mass of sorbitol. The reaction temperature was 130°C and the reaction pressure was 60 mbar. After 5 h of reaction, the selectivity of isosorbitol in the secondary dehydration reaction was measured to be 81.5%. The valve was opened, and the reaction solution was filtered, distilled (distillation temperature 160°C, vacuum degree 5 mbar) and crystallized (the crystallization solvent was a mixture of isopropanol and n-hexane (mass ratio of the two solvents was 12:1) at 20°C, and then dried to obtain the isosorbitol product.

[0088] Isosorbide Synthesis Example 2

[0089] 100g of 75% sorbitol solution was added to the reactor via a pump, along with a solid acid catalyst (phosphotungstic acid solid acid) accounting for 3% of the sorbitol mass as the primary dehydration catalyst. The mixture was heated to 120°C, stirred, and evacuated to a vacuum of 150mba. Water generated during the reaction was discharged from the top of the reactor through a condenser. After 5 hours of reaction, the selectivity of 1,4-dehydrated sorbitol was found to be 93%. The valve was then opened to feed the reaction raw materials into the reactor at a certain rate, while the reaction liquid was passed through a filter screen at the bottom of the reactor to remove the catalyst. The resulting filtrate entered the secondary dehydration reactor.

[0090] The secondary reactor was loaded with a self-made acidic resin catalyst (catalyst preparation example 2) accounting for 3.5% of the mass of sorbitol. The reaction temperature was 135°C and the reaction pressure was 100 mbar. After 5 hours of reaction, the valve was opened, and the selectivity of isosorbitol in the secondary dehydration reaction was detected to be 82.4%. The reaction solution was filtered, distilled (distillation temperature 160°C, distillation vacuum 5 mbar) and crystallized (the crystallization solvent was a mixture of isopropanol and n-hexane (mass ratio of the two solvents 15:1) at 20°C), and then dried to obtain the isosorbitol product.

[0091] Isosorbide Synthesis Example 3

[0092] 100g of 65% sorbitol solution was added to the reactor via a pump, along with a solid acid catalyst (phosphotungstic acid solid acid) accounting for 1% of the sorbitol mass as the primary dehydration catalyst. The mixture was heated to 125°C, stirred, and evacuated to a vacuum of 60mba. Water generated during the reaction was discharged from the top of the reactor through a condenser. After 5 hours of reaction, the selectivity of 1,4-dehydrated sorbitol was found to be 94%. The valve was then opened to feed the reaction raw materials into the reactor at a certain rate, while the reaction liquid was passed through a bottom filter to remove the catalyst. The resulting filtrate entered the secondary dehydration reactor.

[0093] The secondary reactor was loaded with a self-made acidic resin catalyst accounting for 5% of the mass of sorbitol (Preparation Example 3, reaction temperature 140℃, reaction pressure 200mbar, reaction time 3h, after which the selectivity of isosorbitol in the secondary dehydration reaction was 80.9%; the valve was opened, and the reaction solution was filtered, distilled (distillation temperature 160℃, distillation vacuum 5mbar) and crystallized (crystallization solvent was a mixture of isopropanol and n-hexane (mass ratio of the two solvents 17:1), crystallization temperature 20℃, and then dried to obtain the isosorbitol product).

[0094] Isosorbide Synthesis Example 4

[0095] Isosorbide was synthesized according to the method in Example 1 of isosorbide synthesis, except that the self-made acidic resin catalyst 1 was replaced with the catalyst in Example 4 of catalyst preparation.

[0096] Comparative example of isosorbide synthesis

[0097] Isosorbide was synthesized according to the method of Example 1, except that the self-made acidic resin catalyst was replaced with the self-made acidic resin catalyst in Comparative Example 1.

[0098] Detection and calculation methods

[0099] Quantitative analysis of reactants and products was performed using high-performance liquid chromatography (HPLC), and the calculation method is as follows:

[0100] Methods for determining and calculating the selectivity of sorbitol in the primary dehydration reaction 1,4-dehydration:

[0101]

[0102] Methods for detecting and calculating the selectivity of isosorbide in secondary dehydration reactions:

[0103]

[0104] Methods for detecting and calculating the purity and yield of isosorbide products: The purity of isosorbide was detected by liquid chromatography.

[0105] The yield calculation formula is as follows:

[0106] Isosorbide yield = sorbitol conversion × isosorbide selectivity

[0107] Table 1

[0108] Purity of isosorbide products, % Isosorbide yield, % Isosorbide Synthesis Example 1 99.6 81.5 Isosorbide Synthesis Example 2 99.6 82.4 Isosorbide Synthesis Example 3 99.5 80.9 Isosorbide Synthesis Example 4 99.5 81.3 Comparative example of isosorbide synthesis 99.2 72

[0109] Stability test

[0110] The recovered catalyst was used to prepare isosorbide in 10 consecutive batches according to the method for isosorbide synthesis. The purity and yield of the final batch of isosorbide are shown in Table 2. The acidity of the recovered acidic resin catalyst in the final batch was measured by titration, and the results are shown in Table 3.

[0111] Table 2

[0112] Purity of isosorbide products, % Isosorbide yield, % Example 1 99.6 80.5 Example 2 99.6 79.7 Example 3 99.5 80.1 Example 4 99.5 80.3 Comparative Example 95 30.2

[0113] Table 3 Comparison of physical properties before and after catalyst application.

[0114]

[0115] As can be seen from the test results in Tables 1-3 above, the acidic resin catalyst of the present invention exhibits excellent catalytic performance and high-temperature stability in the synthesis reaction of isosorbide. In particular, the combination of the acidic resin catalyst and the solid acid catalyst in the synthesis reaction of isosorbide not only achieves catalytic stability, but also has the characteristics of high isosorbide yield and high selectivity.

[0116] This invention employs a specific acidic resin catalyst combined with a solid acid catalyst and a specific two-stage dehydration reaction to obtain isosorbide with high yield and high selectivity. Moreover, the entire preparation method is catalytically stable, enabling continuous production and possessing extremely high value for widespread application.

[0117] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0118] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0119] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application’s filing, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0120] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0121] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0122] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. An acidic resin catalyst, wherein the polymer in the acidic resin catalyst comprises a first structural unit derived from styrene having an electron-withdrawing group at the meta position of a benzene ring, a second structural unit derived from divinylbenzene, and a third structural unit derived from a propylene sulfonic acid compound represented by Formula I. R1, R2, and R3 are each hydrogen or C1-C2 alkyl groups, and M is H or a metallic element; Furthermore, the benzene rings of the first and second structural units have groups derived from propylene sulfonic acid compounds represented by Formula I or chain segments containing the third structural unit; and M in the polymer is H or a metal element.

2. The acidic resin catalyst according to claim 1, characterized in that: The polymer in the acidic resin catalyst contains structural units shown in Formula 2, Formula 3, and Formula 4. ； ； ； Y1 and Y2 are each a group derived from the compound shown in Formula I or a segment of the corresponding structural unit of the compound shown in Formula I; X is an electron-withdrawing group; R1, R2, and R3 are each hydrogen or C1-C2 alkyl groups.

3. The acidic resin catalyst according to claim 1, characterized in that: The electron-withdrawing group is at least one selected from halogen, nitrosyl, and acetoxy; and / or, Based on the total weight of the polymer as 100wt%, the content of the first structural unit is 1-50wt%; the content of the second structural unit is 30-90wt%; and the content of the third structural unit is 1-50wt%.

4. The acidic resin catalyst according to claim 1, characterized in that: Based on the total weight of the polymer as 100wt%, the content of the first structural unit is 20-40wt%; the content of the second structural unit is 40-60wt%; and the content of the third structural unit is 20-40wt%.

5. The acidic resin catalyst according to any one of claims 1-4, characterized in that: The specific surface area of ​​the acidic resin catalyst is 200-500 m². 2 ∙g -1 ; and / or, The acidic resin catalyst has a pore volume of 0.2-0.8 cm³. 3 ∙g -1 ; and / or, The acidic resin catalyst has a pore size of 1-10 nm; and / or, The acidity of the acidic resin catalyst is 3-8 mmol∙g. -1 ; and / or, The number average molecular weight of the polymer is 10,000-100,000.

6. A method for preparing an acidic resin catalyst according to any one of claims 1-5, comprising the following steps: In the presence of a dispersant and an initiator, divinylbenzene, styrene with electron-withdrawing groups at the meta-position of the benzene ring, and propylene sulfonic acid compounds of Formula I are copolymerized to obtain resin matrix I; or, In the presence of a dispersant and an initiator, divinylbenzene and styrene with electron-withdrawing groups at the meta position of the benzene ring are polymerized to obtain a resin pre-matrix. The resin pre-matrix is ​​then reacted with an propylene sulfonic acid compound as shown in Formula I to obtain resin matrix II. Acidic resin catalysts are obtained by acidifying resin matrix one and / or resin matrix two. R1, R2, and R3 are each hydrogen or C1-C2 alkyl groups, and M is H or a metal element.

7. The preparation method according to claim 6, characterized in that... The preparation method includes the following steps: (1) Method 1: Mix a solution containing a dispersant with a mixture containing divinylbenzene, styrene with electron-withdrawing groups at the meta position of the benzene ring, propylene sulfonic acid compounds, and an initiator to carry out a polymerization reaction to obtain resin matrix 1. Mix resin matrix 1 with an organic solvent containing a pore-expanding agent to obtain a mixture containing resin matrix 1; or, (1) Method 2: Mix a solution containing a dispersant with a mixture containing divinylbenzene, styrene with electron-withdrawing groups at the meta position of the benzene ring, and an initiator to carry out a polymerization reaction to obtain a resin pre-matrix. Then, react the resin pre-matrix with an propylene sulfonic acid compound in an organic solvent containing a pore-expanding agent to obtain a mixture containing resin matrix 2. (2) The mixture of method one and / or method two corresponding to step (1) is contacted with a strong acid for acidification, washed and dried to obtain the acidic resin catalyst.

8. The preparation method according to claim 6 or 7, characterized in that: The dispersant is selected from at least one of polyvinyl alcohol and hydroxyethyl cellulose; and / or, The initiator is an azo compound and / or a peroxide.

9. The preparation method according to claim 6 or 7, characterized in that: The dispersant is selected from polyvinyl alcohol with a number average molecular weight of 150,000-250,000; and / or, The initiator is at least one of benzoyl peroxide, phenylacetyl peroxide, potassium peroxide, and azobisisobutyronitrile.

10. The preparation method according to claim 7, characterized in that: The pore-expanding agent is at least one of toluene, dichloromethane, dichloroethane, and n-heptane.

11. The preparation method according to claim 7, characterized in that: Based on parts by weight, the amount of initiator is 0.2-6 parts relative to 100 parts by weight of all monomers; the amount of dispersant is 1-10 parts; and / or, Based on parts by weight, the amount of pore expander is 2-30 parts relative to 100 parts by weight of resin matrix or resin prematrix.

12. The preparation method according to claim 6 or 7, characterized in that: By weight, the amount of initiator is 0.5-4 parts and the amount of dispersant is 4-6 parts, relative to a total of 100 parts of all monomers.

13. The preparation method according to claim 7, characterized in that: In step (1), the polymerization reaction conditions corresponding to Method 1 and Method 2 are respectively: temperature of 60-150℃, and / or time of 70-140h; and / or, In step (1), the conditions for mixing the resin matrix with the organic solvent containing the pore-expanding agent in method one include: increasing the temperature of the mixture to 30-100°C at a rate of 1-10°C / min; and / or, In step (1), the conditions for reacting the resin pre-matrix with the propylene sulfonic acid compound in an organic solvent containing a pore-expanding agent in method two include: increasing the temperature of the mixture to 30-100℃ at a rate of 1-10℃ / min.

14. The preparation method according to claim 7, characterized in that: The acidification conditions in step (2) include: a temperature of 30-100℃, and / or a time of 5-20 hours; and / or, The strong acid is selected from at least one of concentrated sulfuric acid, chlorosulfonic acid, fuming sulfuric acid, and methanesulfonic acid.

15. The use of an acidic resin catalyst according to any one of claims 1-5 or an acidic resin catalyst prepared by any one of claims 6-14 in the preparation of isosorbide.

16. A continuous preparation method of isosorbide, comprising the following steps: 1) Hexitol is reacted with a solid acid catalyst to carry out a primary dehydration reaction, yielding a primary dehydration reaction mixture; 2) Remove the solid acid catalyst from the primary dehydration reaction mixture, and then contact the resulting mixture with an acidic resin catalyst to carry out a secondary dehydration reaction to obtain a reaction product containing isosorbide. The acidic resin catalyst is the acidic resin catalyst according to any one of claims 1-5 and / or the acidic resin catalyst prepared by the preparation method according to any one of claims 6-14.

17. The continuous preparation method of isosorbide according to claim 16, characterized in that: The hexitol is selected from sorbitol and / or 1,4-anhydrosorbitol, and / or the hexitol is derived from solid hexitol and / or a solution of hexitol; and / or The solid acid catalyst is selected from at least one of molecular sieves, acidic resins, metal phosphates, Lewis acids, and heteropolyacid catalysts.

18. The continuous preparation method of isosorbide according to claim 16, characterized in that: The solid acid catalyst is selected from at least one of heteropoly acids and acidic resins.

19. The continuous preparation method of isosorbide according to claim 16, characterized in that: The solid acid catalyst is a heteropoly acid.

20. The continuous preparation method of isosorbide according to claim 16, characterized in that: The solid acid catalyst is a phosphotungstic acid solid acid catalyst.

21. The continuous preparation method of isosorbide according to any one of claims 16-20, characterized in that: In the primary dehydration reaction, the mass ratio of the solid acid catalyst to hexitol is (1-10):100; and / or, the selectivity of 1,4-dehydrated sorbitol in the primary dehydration reaction is controlled to be above 80%; and / or, In the secondary dehydration reaction, the mass ratio of the acidic resin catalyst to hexitol is (1-10):100; and / or, the selectivity of isosorbide in the secondary dehydration reaction is controlled to be above 80%.

22. The continuous preparation method of isosorbide according to any one of claims 16-20, characterized in that: In the primary dehydration reaction, the mass ratio of the solid acid catalyst to hexitol is (3-5):100; and / or, In the secondary dehydration reaction, the mass ratio of the acidic resin catalyst to hexitol is (2-4):100; and / or, the selectivity of isosorbide in the secondary dehydration reaction is controlled to be above 80%.

23. The continuous preparation method of isosorbide according to any one of claims 16-20, characterized in that: The conditions in step 1) include: The reaction temperature is 80-130℃, and / or the residence time is 3-7 h, and / or the reaction pressure is 0-1 atm; and / or, The conditions in step 2) include: The reaction temperature is 120-160℃, and / or the residence time is 5-9h, and / or the reaction pressure is 0-1atm.

24. The continuous preparation method of isosorbide according to any one of claims 16-20, characterized in that: The water generated in the primary dehydration reaction is discharged from the top of the reactor during the reaction, and / or the primary dehydration reaction mixture is dehydrated before entering the secondary dehydration reaction; And / or, The continuous preparation method further includes separating and purifying the obtained reaction product containing isosorbide after the secondary dehydration reaction to obtain purified isosorbide.

25. The continuous preparation method of isosorbide according to any one of claims 16-20, characterized in that: The primary dehydration reaction mixture is dehydrated before entering the secondary dehydration reaction by means of a dehydration tower; and / or, The continuous preparation method further includes separating and purifying the obtained reaction product containing isosorbide after the secondary dehydration reaction to obtain purified isosorbide; the purification method is distillation and / or crystallization.

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