Epoxy-ring-opening bifunctional catalyst, preparation method and application thereof

Abstract

The application discloses an epoxy-opening bifunctional catalyst and a preparation method and application thereof, and belongs to the field of catalyst materials and biomass chemical technology. The catalyst takes mesoporous molecular sieve SBA-15 as a carrier, combines tungsten and molybdenum active components with an aluminum-doped silicon-based skeleton through co-assembly and a hydrothermal method, and forms a solid acid catalyst with a bifunctional active center. The total loading amount of tungsten and molybdenum is 10wt% of the mass of the silicon source, the molar ratio of W to Mo is 3:7-7:3, and the molar ratio of silicon to aluminum is 10-30. The preparation comprises template self-assembly, co-hydrolysis of a silicon-aluminum source and a tungsten-molybdenum source, hydrothermal crystallization, programmed temperature calcination and the like. The catalyst is applied to the one-pot epoxy-opening preparation of biomass polyols from vegetable oil acid methyl ester, and simultaneously realizes the epoxidation and ring-opening reactions under mild conditions. The obtained polyols have the characteristics of low viscosity, low acid value and high hydroxyl value.

Description

Technical Field

[0001] This invention relates to the fields of catalyst materials and biomass chemical technology, specifically to an epoxy-ring-opening bifunctional catalyst and its preparation method and application. Background Technology

[0002] With increasing global emphasis on sustainable development and green chemistry, developing and utilizing renewable biomass resources to replace traditional fossil resources has become a crucial direction for scientific research and industry. Among these, vegetable oils, due to their wide availability, low cost, and highly modifiable molecular structure, are considered ideal platform compounds for the preparation of bio-based chemicals and materials. In particular, the conversion of vegetable oils into polyols through chemical modification, which can partially or completely replace petroleum-based polyether polyols in polyurethane synthesis, has extremely significant economic and environmental value.

[0003] Currently, among the technical routes for preparing polyols from vegetable oils, the "epoxidation-ring-opening" route based on the carbon-carbon double bonds in unsaturated fatty acid chains is one of the most thoroughly studied and has the greatest application potential. This route typically consists of two independent steps: the first step is epoxidation, where, in the presence of a catalyst, an oxidant (such as hydrogen peroxide) is used to convert the carbon-carbon double bonds in vegetable oils into highly reactive epoxy groups; the second step is ring-opening, where, under the action of an acid catalyst, the generated epoxy groups react with water, alcohols, etc., to introduce the desired hydroxyl functional groups.

[0004] However, this traditional two-step process has several bottlenecks that urgently need to be addressed. First, the process is lengthy and complex, resulting in high energy consumption. After the epoxidation reaction, the intermediate epoxidized vegetable oil must undergo tedious neutralization, washing, and purification to remove residual catalyst and stabilize the product before the second-step ring-opening reaction can proceed. This significantly increases operating time and energy consumption. Second, the catalyst system has limitations. Traditional epoxidation reactions often use homogeneous inorganic strong acids or carboxylic acids as catalysts. These catalysts are difficult to recover after the reaction, leading to resource waste and the generation of large amounts of acidic wastewater and waste residue, resulting in severe environmental pressure and subsequent treatment costs. Furthermore, from the perspective of product quality, in epoxidation systems involving carboxylic acids, premature ring-opening of epoxy groups under acidic conditions is prone to occur, resulting in a high acid value, low target hydroxyl value, uneven functionality distribution, and often high product viscosity, which is detrimental to subsequent storage, transportation, and polyurethane synthesis and processing.

[0005] Therefore, to address the aforementioned problems, this invention provides an epoxy-ring-opening bifunctional catalyst, its preparation method, and its application. By carefully designing and constructing a porous composite catalytic material integrating a transition metal epoxy active center and a solid acid ring-opening active center, a one-pot "epoxy-ring-opening" cascade reaction using methyl oleate as a raw material is achieved under mild conditions without the addition of external carboxylic acid. This achieves the comprehensive goals of simplifying the process, reducing energy consumption and waste emissions, improving atom economy, and obtaining high-quality biomass polyols with low acid value, low viscosity, and high hydroxyl value. Summary of the Invention

[0006] The purpose of this invention is to provide an epoxy-ring-opening bifunctional catalyst, its preparation method and application, which realizes the one-pot reaction of epoxy-ring-opening cascade using methyl oleate as raw material under mild conditions without the addition of external carboxylic acid.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] An epoxy-ring-opening bifunctional catalyst is disclosed, wherein the catalyst uses a mesoporous molecular sieve SBA-15 as a support and simultaneously loads tungsten (W) and molybdenum (Mo) active metal components; the mesoporous molecular sieve SBA-15 is prepared by hydrothermal synthesis from a silicon source and an aluminum source, wherein the silicon source is selected from tetraethyl silicate, tetramethyl silicate, or sodium silicate, and the aluminum source is selected from aluminum chloride or aluminum isopropoxide; wherein the total loading of tungsten and molybdenum is 10 wt% of the silicon source mass (mW + mMo = 10% mSi) based on metal mass, and the molar ratio of tungsten (W) to molybdenum (Mo) is (3:7) to (7:3); the mesoporous molecular sieve framework is doped with aluminum (Al), and the silicon / Al molar ratio of the framework is 10 to 30.

[0009] This application also claims a method for preparing the above-mentioned epoxy-ring-opening bifunctional catalyst, comprising the following steps:

[0010] S1. Dissolve the template agent polyether P123 in deionized water, add acidic solution to adjust the pH of the mixed solution to 0.5~3, and stir at 40℃ for 1~6 hours;

[0011] S2. Add silicon source and aluminum source to the mixed solution of step S1, and stir at 40°C for 0.5 to 2 hours to form a carrier precursor; then add molybdenum source and tungsten source, and continue stirring at 40°C for 12 to 36 hours to obtain a mixed solution precursor.

[0012] S3. The mixed solution precursor obtained in step S2 is transferred to a hydrothermal reactor and hydrothermally treated at 80~120℃ for 24~72 hours. After hydrothermal treatment, it is filtered and washed with deionized water and dried at 70℃ for 12~24 hours to obtain the catalyst precursor.

[0013] S4. The catalyst precursor obtained in step S3 is subjected to a heating and calcination process in air atmosphere: first, the temperature is increased to 200-400℃ at a rate of 2-20℃ / min and held for 0.5-2 hours; then, the temperature is increased to 450-650℃ at a rate of 2-20℃ / min and calcined for 4.5-6.5 hours to obtain the epoxy-ring-opening bifunctional catalyst.

[0014] Preferably, in step S1, the acidic solution is selected from one or more of hydrochloric acid, phosphoric acid, nitric acid, and fluoroboric acid; the pH of the mixed solution is adjusted to 1-1.5 by adding the acidic solution, and the mixture is stirred at 40°C for 2-4 hours; the mass ratio of polyether P123 to deionized water is 1:30.

[0015] Preferably, in step S2, the silicon source is selected from one of tetraethyl silicate, tetramethyl silicate, or sodium silicate; the aluminum source is selected from one of aluminum chloride or aluminum isopropoxide; the molybdenum source is selected from one of ammonium molybdate, phosphomolybdic acid, or ammonium heptamolybdate; the tungsten source is selected from one of ammonium tungstate, ammonium metatungstate, or sodium tungstate; and the mass ratio of the silicon source to polyether P123 is 9:4.

[0016] Preferably, in step S3, the hydrothermal treatment temperature is 100°C and the hydrothermal time is 24 hours.

[0017] Preferably, in step S4, the heating and calcination process is as follows: heating to 300°C at a rate of 5~10°C / min and holding for 0.5 hours, then heating to 550°C at a rate of 5~10°C / min and holding for 5.5 hours.

[0018] This application also claims the use of the above-mentioned epoxy-ring-opening bifunctional catalyst in the one-pot epoxy-ring-opening preparation of biomass polyols from methyl oleate.

[0019] Preferably, the application includes the following steps:

[0020] (1) The vegetable oil, alkaline catalyst and methanol mixture was subjected to methyl esterification pretreatment at 50~100℃. After the reaction was carried out for 0.5~3h, an acidic reagent was added to terminate the reaction. The product was washed with water until neutral and then subjected to vacuum distillation to obtain methyl vegetable oil oleate, the raw material of the epoxy-ring-opening one-pot method.

[0021] (2) The vegetable oleate methyl ester, bifunctional catalyst, deionized water and solvent are fully preheated in a container and stirred at a constant temperature of 100-300 rpm at 40-100℃ to obtain a mixture;

[0022] (3) Add hydrogen peroxide solution dropwise to the mixture in step (2) and react at 40~100℃ for 4~24 hours to complete the epoxy-ring-opening one-pot reaction;

[0023] (4) The mixed product prepared by the epoxy-ring-opening one-pot method is separated into liquids and washed with deionized water. The pH of the mixed product is washed to neutral, and then dried and rotary distilled to obtain the biomass polyol.

[0024] Preferably, in step (1), the vegetable oil is selected from tung oil, palm oil, soybean oil, castor oil, sunflower seed oil or camellia oil; the alkaline catalyst is selected from sodium hydroxide or potassium hydroxide; and the acidic reagent is selected from phosphoric acid, hydrochloric acid or nitric acid.

[0025] Preferably, in step (1), the reaction temperature of the methyl esterification pretreatment is 70±5℃ and the reaction time is 1~1.5h.

[0026] Preferably, in step (2), the amount of the bifunctional catalyst added is 4-5 wt% of the mass of methyl oleate, the amount of deionized water added is 30-50 wt%, and the solvent is selected from ethyl acetate, tetrahydrofuran or trimethylamine dihydrate, and the amount added is 100-300 wt%.

[0027] Preferably, in step (2), the mixture is obtained by constant temperature stirring at 200 rpm at 50~80℃.

[0028] Preferably, in step (3), the one-pot reaction temperature is 50~80℃ and the reaction time is 8~12 hours; the concentration of the hydrogen peroxide solution is 30% and the dropping rate is 0.01~0.015mL / s.

[0029] Working Mechanism of this Invention: The epoxy-ring-opening bifunctional catalyst provided by this invention achieves a complete cascade catalytic process from epoxidation to ring opening through its ingenious composition and structural design. The catalyst uses ordered mesoporous molecular sieve SBA-15 as a support, whose unique pore structure provides ample mass transfer channels and reaction sites for reactant molecules. In the initial stage of the reaction, the tungsten and molybdenum transition metal active sites supported on the catalyst surface react with hydrogen peroxide to generate highly oxidizing metal peroxide species (MOOH) in situ. These active species preferentially attack the carbon-carbon double bonds in the long chain of methyl oleate, selectively converting them into epoxy groups through an efficient oxygen atom transfer mechanism, forming an epoxy methyl oleate intermediate.

[0030] As the epoxidation reaction proceeds, the bifunctional acid centers generated by aluminum doping in the catalyst begin to play a crucial role. On one hand, the Si-OH-Al structure in the framework provides Brønsted acid sites, releasing protons to activate the epoxy groups; on the other hand, unsaturated coordinated Al³⁺ and other metal species provide Lewis acid sites, enhancing the electrophilicity of the epoxy groups through electronic effects. Under the synergistic effect of the dual acid centers, water molecules in the reaction system act as green ring-opening agents, launching a nucleophilic attack on the activated epoxy groups, causing the epoxy ring to cleave and generate the corresponding ortho-diol structure, successfully introducing hydroxyl functional groups onto the molecular chain.

[0031] The close spatial arrangement and synergistic effect of these bifunctional active centers ensure that the intermediates generated in the epoxidation reaction can undergo ring-opening reactions at nearby acidic sites without long-range diffusion, forming a highly efficient "reaction-transfer" continuous process. The entire process is carried out under mild conditions, without the need for external co-catalysts such as carboxylic acids. This not only avoids side reactions and ring-opening isomerization of epoxy groups caused by excessive acidity in traditional processes, but also significantly reduces the acid value and viscosity of the product. Ultimately, this achieves the process goal of efficiently converting methyl oleate into high-quality biomass polyols in a one-pot process, while simultaneously reducing emissions of waste, embodying the core concept of green chemistry.

[0032] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0033] 1. This invention significantly reduces product viscosity, improves product performance and ease of application. By pretreating vegetable oil with methyl esterification, it converts it into methyl oleate as a reaction raw material. The viscosity of the polyol product prepared in this way is much lower than that of the product obtained by directly using the original vegetable oil. The low viscosity not only significantly improves the mass transfer efficiency in the reaction system and increases the reaction rate of the "one-pot" method, but also makes the final product more advantageous in storage, transportation and subsequent polyurethane synthesis and other processing.

[0034] 2. This invention achieves a highly efficient one-pot cascade reaction, simplifying the process flow. The bifunctional catalyst provided by this invention successfully integrates the active centers of the epoxidation and ring-opening reactions into one, realizing the one-pot synthesis of polyols from raw materials. This completely solves the problems of cumbersome process flow, intermittent operation, and high energy consumption in the traditional two-step method, greatly simplifying the production steps and improving production efficiency.

[0035] 3. This invention has high atom economy and mild reaction conditions. In the reaction design, the byproduct water generated after hydrogen peroxide participates in the epoxidation reaction can be directly used as a reagent for the next ring-opening reaction, realizing efficient utilization of reactants and high atom economy. At the same time, the entire cascade reaction can be carried out under mild temperature conditions, reducing energy consumption and process control difficulty.

[0036] 4. This invention uses a solid acid catalyst, which completely avoids the use of homogeneous inorganic acid or carboxylic acid catalysts in traditional processes. This not only solves the problem of excessively high product acid value caused by acid catalyst residue from the source and ensures product quality, but also makes the catalyst easy to recycle and reuse, greatly reducing the discharge of acidic wastewater and waste residue and subsequent treatment costs, which meets the requirements of green chemical development.

[0037] 5. The catalyst of this invention features dual-function synergy, offering multiple uses with a single catalyst at a low cost. This catalyst possesses both a metallic active center (W / Mo) and an acidic center (derived from Al doping), which are spatially close and work synergistically to ensure high efficiency and selectivity in the epoxy-ring-opening cascade reaction. One catalyst replaces two (or more) catalysts in traditional processes, achieving "multiple uses with one catalyst" and reducing the cost of catalyst use and management. Attached Figure Description

[0038] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, some of the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can be made based on these drawings without creative effort.

[0039] Figure 1 These are scanning electron microscope (SEM) images of the 11WMO@Al-SBA-15 catalyst used in Example 1 of this invention. Figure a shows the catalyst morphology and structure at 1000x magnification; Figure b shows the catalyst morphology and pore structure at 10000x magnification; Figure c shows the catalyst morphology and pore structure at 20000x magnification; and Figure d shows the catalyst morphology and pore structure at 50000x magnification.

[0040] Figure 2 This is a comparison spectrum of the FT-IR characterization and analysis results of biomass polyols prepared in Example 2 and Comparative Example 1 of the present invention. Detailed Implementation

[0041] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific implementation schemes are now described in detail.

[0042] The present invention will be further described below with reference to embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0043] Synthesis example 1

[0044] This synthetic example provides a method for preparing an epoxy-ring-opening bifunctional catalyst, comprising the following steps:

[0045] S1. Dissolve 2.0g of template agent polyether P123 in 65mL of deionized water, add 20mL of 4mol / L HCl solution, and stir at 40℃ for 2h until P123 is completely dissolved.

[0046] S2. Add 4.5g tetraethyl silicate and 0.44g aluminum isopropoxide to the mixed solution in step S1, stir at 40°C for 1 hour, then add 0.0558g ammonium molybdate and 0.0407g ammonium metatungstate, stir at 40°C for 24 hours to obtain the mixed solution precursor.

[0047] S3. The mixed solution precursor obtained in step S2 is transferred to a hydrothermal reactor and hydrothermally heated at 100°C for 48 hours. Then it is washed and filtered with deionized water and dried at 70°C for 12 hours.

[0048] S4. Place the dried catalyst precursor from step S3 into a tube furnace, heat it to 300°C at a rate of 10°C / min under air atmosphere, hold for 0.5 h, and then continue to heat it to 550°C at a rate of 10°C / min and calcine for 5.5 h to obtain the epoxy-ring-opening bifunctional catalyst, denoted as 11WMo@Al-SBA-15.

[0049] Synthesis example 2

[0050] This synthetic example provides a method for preparing an epoxy-ring-opening bifunctional catalyst, comprising the following steps:

[0051] S1. Dissolve 2.0g of template agent polyether P123 in 65mL of deionized water, add 20mL of 4mol / L HCl solution, and stir at 40℃ for 2h until P123 is completely dissolved.

[0052] S2. Add 4.5g tetraethyl silicate and 0.44g aluminum isopropoxide to the mixed solution in step S1, stir at 40°C for 1 hour, then add 0.0335g ammonium molybdate and 0.0569g ammonium metatungstate, and stir at 40°C for 24 hours.

[0053] S3. The mixed solution precursor obtained in step S2 is transferred to a hydrothermal reactor and hydrothermally heated at 100°C for 48 hours. After washing and filtering with deionized water, it is dried at 70°C for 12 hours.

[0054] S4. The catalyst precursor dried in step S3 is placed in a tube furnace and heated to 300°C at a rate of 10°C / min under air atmosphere, held for 0.5 h, and then heated to 550°C at a rate of 10°C / min for calcination for 5.5 h to obtain the epoxy-ring-opening bifunctional catalyst, denoted as 73WMo@Al-SBA-15.

[0055] Synthesis example 3

[0056] This synthetic example provides a method for preparing an epoxy-ring-opening bifunctional catalyst, comprising the following steps:

[0057] S1. Dissolve 2.0g of template agent polyether P123 in 65mL of deionized water, add 20mL of 4mol / L HCl solution, and stir at 40℃ for 2h until P123 is completely dissolved.

[0058] S2. Add 4.5g tetraethyl silicate and 0.44g aluminum isopropoxide to the mixed solution in step S1, stir at 40°C for 1 hour, then add 0.0782g ammonium molybdate and 0.0244g ammonium metatungstate, and stir at 40°C for 24 hours.

[0059] S3. The mixed solution precursor obtained in step S2 is transferred to a hydrothermal reactor and hydrothermally heated at 100°C for 48 hours. After washing and filtering with deionized water, it is dried at 70°C for 12 hours.

[0060] S4. Place the dried catalyst precursor from step S3 in a tube furnace and heat it to 300°C at a rate of 10°C / min under air atmosphere. Hold the temperature for 0.5 h and then continue heating it to 550°C at a rate of 10°C / min. Calcinate the catalyst for 5.5 h to obtain the epoxy-ring-opening bifunctional catalyst, denoted as 37WMo@Al-SBA-15.

[0061] The epoxy-ring-opening bifunctional catalyst prepared by the above synthesis example was analyzed by X-ray fluorescence spectroscopy (XRF), and the results are shown in Table 1.

[0062] Table 1

[0063]

[0064] Example 1

[0065] See appendix Figure 1 This embodiment provides an application of an epoxy-ring-opening bifunctional catalyst in the one-pot epoxy-ring-opening process of methyl oleate to prepare biomass polyols, comprising the following steps:

[0066] (1) The vegetable oil was pretreated by methyl esterification at 70°C with a mixed solution of alkaline catalyst and methanol. After reacting for 1.5 h, an acidic reagent was added to terminate the reaction. The product was washed with water until neutral and then distilled under reduced pressure to obtain methyl vegetable oil ester, the raw material of the epoxy-ring-opening one-pot method.

[0067] (2) Add 10.0g of methyl tung oil, 5.0g of deionized water, 0.3g of bifunctional catalyst 11WMo@Al-SBA-15, and 25g of ethyl acetate to a three-necked flask. Heat and stir in a water bath at 70°C at a stirring rate of 200 rpm to obtain a mixture.

[0068] (3) Add 20.0g of 30% hydrogen peroxide solution dropwise to the mixture in step (2) at a rate of 0.015mL / s; stir the reaction at a constant temperature for 12h to complete the epoxy-ring-opening one-pot reaction.

[0069] (4) The mixed product prepared by the epoxy-ring-opening one-pot method was transferred to a separatory funnel, the upper liquid was taken, washed with deionized water, and the pH was adjusted to neutral. The mixture was then placed in a rotary evaporator and rotary evaporated at a vacuum of 0.1 MPa and 70°C to obtain the final product, biomass polyol.

[0070] Example 2

[0071] See appendix Figure 2 This embodiment provides an application of an epoxy-ring-opening bifunctional catalyst in the one-pot epoxy-ring-opening process of methyl oleate to prepare biomass polyols, comprising the following steps:

[0072] (1) The vegetable oil was pretreated by methyl esterification at 70°C with a mixed solution of alkaline catalyst and methanol. After reacting for 1.5 h, an acidic reagent was added to terminate the reaction. The product was washed with water until neutral and then distilled under reduced pressure to obtain methyl vegetable oil ester, the raw material of the epoxy-ring-opening one-pot method.

[0073] (2) Add 10.0g of methyl tung oil, 5.0g of deionized water, 0.3g of bifunctional catalyst 11WMo@Al-SBA-15, and 25g of ethyl acetate to a three-necked flask. Heat and stir in a water bath at 60°C at a stirring rate of 200 rpm to obtain a mixture.

[0074] (3) Add 20.0g of 30% hydrogen peroxide solution dropwise to the mixture in step (2) at a rate of 0.015mL / s; stir the reaction at a constant temperature for 12h to complete the epoxy-ring-opening one-pot reaction.

[0075] (4) The mixed product prepared by the epoxy-ring-opening one-pot method was transferred to a separatory funnel, the upper liquid was taken, washed with deionized water, and the pH was adjusted to neutral. The mixture was then placed in a rotary evaporator and rotary evaporated at a vacuum of 0.1 MPa and 70°C to obtain the final product, biomass polyol.

[0076] Example 3

[0077] This embodiment provides an application of an epoxy-ring-opening bifunctional catalyst in the one-pot epoxy-ring-opening process of methyl oleate to prepare biomass polyols, including the following steps:

[0078] (1) The vegetable oil was pretreated by methyl esterification at 70°C with a mixed solution of alkaline catalyst and methanol. After reacting for 1.5 h, an acidic reagent was added to terminate the reaction. The product was washed with water until neutral and then distilled under reduced pressure to obtain methyl vegetable oil ester, the raw material of the epoxy-ring-opening one-pot method.

[0079] (2) Add 10.0g of methyl tung oil, 5.0g of deionized water, 0.5g of bifunctional catalyst 11WMo@Al-SBA-15, and 25g of ethyl acetate to a three-necked flask. Heat and stir in a water bath at 60°C at a stirring rate of 200 rpm to obtain a mixture.

[0080] (3) Add 20.0g of 30% hydrogen peroxide solution dropwise to the mixture in step (2) at a rate of 0.015mL / s; stir the reaction at a constant temperature for 12h to complete the epoxy-ring-opening one-pot reaction.

[0081] (4) The mixed product prepared by the epoxy-ring-opening one-pot method was transferred to a separatory funnel, the upper liquid was taken, washed with deionized water, and the pH was adjusted to neutral. The mixture was then placed in a rotary evaporator and rotary evaporated at a vacuum of 0.1 MPa and 70°C to obtain the final product, biomass polyol.

[0082] Example 4

[0083] This embodiment provides an application of an epoxy-ring-opening bifunctional catalyst in the one-pot epoxy-ring-opening process of methyl oleate to prepare biomass polyols, including the following steps:

[0084] (1) The vegetable oil was pretreated by methyl esterification at 70°C with a mixed solution of alkaline catalyst and methanol. After reacting for 1.5 h, an acidic reagent was added to terminate the reaction. The product was washed with water until neutral and then distilled under reduced pressure to obtain methyl vegetable oil ester, the raw material of the epoxy-ring-opening one-pot method.

[0085] (2) Add 10.0g of methyl tung oil, 5.0g of deionized water, 0.3g of bifunctional catalyst 73WMo@Al-SBA-15, and 25g of ethyl acetate to a three-necked flask. Heat and stir in a water bath at 60°C at a stirring rate of 200rpm. Stir at a constant temperature to obtain a mixture.

[0086] (3) Add 20.0g of 30% hydrogen peroxide solution dropwise to the mixture in step (2) at a rate of 0.015mL / s; stir the reaction at a constant temperature for 12h to complete the epoxy-ring-opening one-pot reaction.

[0087] (4) The mixed product prepared by the epoxy-ring-opening one-pot method was transferred to a separatory funnel, the upper liquid was taken, washed with deionized water, and the pH was adjusted to neutral. The mixture was then placed in a rotary evaporator and rotary evaporated at a vacuum of 0.1 MPa and 70°C to obtain the final product, biomass polyol.

[0088] Example 5

[0089] This embodiment provides an application of an epoxy-ring-opening bifunctional catalyst in the one-pot epoxy-ring-opening process of methyl oleate to prepare biomass polyols, including the following steps:

[0090] (1) The vegetable oil was pretreated by methyl esterification at 70°C with a mixed solution of alkaline catalyst and methanol. After reacting for 1.5 h, an acidic reagent was added to terminate the reaction. The product was washed with water until neutral and then distilled under reduced pressure to obtain methyl vegetable oil ester, the raw material of the epoxy-ring-opening one-pot method.

[0091] (2) Add 10.0g of methyl tung oil, 5.0g of deionized water, 0.3g of bifunctional catalyst 37WMo@Al-SBA-15, and 25g of ethyl acetate to a three-necked flask. Heat and stir in a water bath at 70°C at a stirring rate of 200 rpm to obtain a mixture.

[0092] (3) Add 20.0g of 30% hydrogen peroxide solution dropwise to the mixture in step (2) at a rate of 0.015mL / s; stir the reaction at a constant temperature for 12h to complete the epoxy-ring-opening one-pot reaction.

[0093] (4) The mixed product prepared by the epoxy-ring-opening one-pot method was transferred to a separatory funnel, the upper liquid was taken, washed with deionized water, and the pH was adjusted to neutral. The mixture was then placed in a rotary evaporator and rotary evaporated at a vacuum of 0.1 MPa and 70°C to obtain the final product, biomass polyol.

[0094] Comparative Example 1

[0095] See appendix Figure 2This embodiment provides an application of an epoxy-ring-opening bifunctional catalyst in the one-pot epoxy-ring-opening process of methyl oleate to prepare biomass polyols, comprising the following steps:

[0096] (1) The vegetable oil was pretreated by methyl esterification at 70°C with a mixed solution of alkaline catalyst and methanol. After reacting for 1.5 h, an acidic reagent was added to terminate the reaction. The product was washed with water until neutral and then distilled under reduced pressure to obtain methyl vegetable oil ester, the raw material of the epoxy-ring-opening one-pot method.

[0097] (2) Add 10.0g of methyl tung oil, 5.0g of deionized water, 0.3g of bifunctional catalyst 11WMo@Al-SBA-15, and 25g of ethyl acetate to a three-necked flask. Heat and stir in a water bath at 60°C at a stirring rate of 200 rpm to obtain a mixture.

[0098] (3) Add 20.0g of 30% hydrogen peroxide solution dropwise to the mixture in step (2) at a rate of 0.015mL / s; stir the reaction at a constant temperature for 6h to complete the epoxy-ring-opening one-pot reaction.

[0099] (4) The mixed product prepared by the epoxy-ring-opening one-pot method was transferred to a separatory funnel, the upper liquid was taken, washed with deionized water, and the pH was adjusted to neutral. The mixture was then placed in a rotary evaporator and rotary evaporated at a vacuum of 0.1 MPa and 70°C to obtain the final product, biomass polyol.

[0100] Comparative Example 2

[0101] (1) Add 30.0g raw tung oil, 6.0g formic acid, 5.0g deionized water and 0.15g 75% phosphoric acid to a three-necked flask, heat in a water bath at 60°C and stir at a stirring rate of 200rpm, and stir at a constant temperature to obtain a mixture;

[0102] (2) 27.0 g of 30% hydrogen peroxide solution was added dropwise to the mixture in step (1) at a rate of 0.015 mL / s; the mixture was stirred at a constant temperature for 12 h to obtain the mixed product.

[0103] (3) Transfer the mixed product to a separatory funnel, take the upper liquid, wash it with deionized water, adjust the pH to neutral, and place it in a rotary evaporator. The final product, biomass polyol, is obtained by rotary evaporation at a vacuum of 0.1 MPa and 70°C.

[0104] The biomass polyols prepared in the above examples and comparative examples were tested, and the test results are shown in Table 2.

[0105] Table 2

[0106]

[0107] The test results show that the acid value and viscosity of the biomass polyols prepared by catalytic reaction using WMo@Al-SBA-15 as a catalyst (Examples 1-5) are significantly lower than those of the biomass polyols prepared by catalyzing with inorganic acids as a catalyst (Comparative Example 2). Furthermore, when WMo@Al-SBA-15 is used as a catalyst, the double bond selectivity of the products obtained with a reaction time of 12 h (Examples 1-5) is generally better than that obtained with a reaction time of 6 h (Comparative Example 1).

[0108] The hydroxyl value was tested according to the method in GB / T12008.3-2009 Plastics Polyether Polyols Part 3: Determination of Hydroxyl Value. mg of sample was dissolved in an acylation reagent and reacted at 115℃ for 0.5 h. Phenolphthalein-pyridine indicator was added, and the reaction was titrated with 0.5 mol / L NaOH standard solution until a pale red color persisted for 30 seconds, which was the endpoint. The volume of NaOH standard solution consumed, V1, was recorded. Simultaneously, the volume of NaOH consumed in the blank group, V2, was recorded. The hydroxyl value OHV (mgKOH / g) of the product was calculated using the following formula:

[0109] Formula I;

[0110] Where: V2—the volume of NaOH solution consumed by the sample, mL;

[0111] V1 — Volume of NaOH solution consumed in the blank, mL;

[0112] c — Concentration of the sodium hydroxide standard solution, in mol / L;

[0113] m—sample mass, g;

[0114] The acid value C of tung oil-based polyols was determined according to GB / T12008.5-2010. A mg sample was dissolved in an ethanol-tetrahydrofuran solvent, phenolphthalein indicator was added, and titration was performed with a 0.02 mol / L KOH-ethanol standard solution until a pale pink color persisted for 30 seconds, which was the endpoint. The volume of KOH-ethanol standard solution consumed was recorded as N. The formula for calculating the product acid value C (mgKOH / g) is as follows:

[0115] Formula II;

[0116] Where: A—the volume of KOH solution consumed by the sample, mL;

[0117] N – Concentration of KOH-ethanol standard solution, mol / L;

[0118] m—sample mass, g;

[0119] The final corrected hydroxyl value of the sample is OHV1 = OHV + C;

[0120] Determination of double bond conversion rate: The method is as follows: Dissolve a certain mass of the sample in a cyclohexane-glacial acetic acid (equal volumes mixed) solvent. Add 25.00 mL of Widmanstätten reagent, followed by 20 mL of potassium iodide solution. Titrate with standardized sodium thiosulfate solution until the yellow color of iodine almost disappears. Add a few drops of starch solution and continue titrating until the blue color just disappears. Calculate the iodine value of the sample using the formula:

[0121] Formula II;

[0122] Wherein: W—Iodine value of the sample, g / 100g;

[0123] c—Concentration of sodium thiosulfate standard solution, mol / L;

[0124] V1 — Volume of sodium thiosulfate solution consumed in the blank, mL;

[0125] V2 — The volume of sodium thiosulfate solution consumed by the sample, in mL;

[0126] m—sample mass, g;

[0127] Double bond conversion rate (%) = 1 - (iodine value of product polyol / iodine value of reactant raw material) × 100%;

[0128] Viscosity was measured using a viscometer NDJ-5S.

[0129] Infrared spectroscopy determination method: The biomass polyol samples were analyzed using a Spectrum 3FT-MIR Fourier transform infrared spectrometer in the wavelength range of 600~4000 cm⁻¹. -1 Spectral analysis tests were performed inside.

[0130] Method for determining scanning electron microscopy images: The morphology and pore structure of the catalyst were scanned using a Czech TESCANMIRALMS scanning electron microscope at magnifications of 1000-50000.

[0131] Biomass polyols were prepared from Example 2 and Comparative Example 1, and the products were named T-Polyol-12h and T-Polyol-6h, respectively. FT-IR characterization analysis was performed on them, and the resulting FT-IR spectra are shown below. Figure 2 The images shown, from top to bottom, are the infrared spectra of raw tung oil (TO), methyl tung oilate (TOME), tung oil-based polyol (T-Polyol-6h), and tung oil-based polyol 1 (T-Polyol-12h). The 3400 cm⁻¹... -1 The peak attributable to the OH stretching vibration of the hydroxyl group; 3012 cm⁻¹ -1The peak at 991 cm⁻¹ belongs to the CH stretching vibration of a carbon-carbon double bond; the peak at 830 cm⁻¹ belongs to the CH bending vibration of a carbon-carbon conjugated double bond; -1 The characteristic absorption peaks are attributed to the epoxy bond. Comparison shows that after methylation, TOME and T-polyol-6h still retain the characteristic peak of the carbon-carbon double bond (3012 cm⁻¹). -1 991cm -1 The characteristic peaks of the T-polyol-12h double bond disappeared, and a distinct -OH characteristic peak (3400 cm⁻¹) appeared. -1 This demonstrates that the tung oil-based polyol product after a 6-hour reaction time was not completely epoxidized and still contained carbon-carbon double bond functional groups. However, after a 12-hour one-pot epoxidation-ring-opening reaction, TOME was completely converted into tung oil-based polyol. The reaction of TOME and T-Polyol-12h at 830 cm⁻¹ further supports this finding. -1 The absence of characteristic peaks for epoxy bonds at all locations proves that the one-pot method successfully achieved the epoxidation reaction of the carbon-carbon double bonds in methyl tung oil and the subsequent ring-opening reaction.

[0132] In summary, this invention achieves efficient and green preparation of vegetable oil-based polyols through the synergistic innovation of methyl esterification pretreatment and a bifunctional catalyst. Its significant advantages include: a substantial reduction in product viscosity, improving product performance and processing convenience; a simplified process flow and increased production efficiency through a one-pot cascade reaction; high atom economy by utilizing water, a byproduct of hydrogen peroxide reaction, as a ring-opening reagent; elimination of acid pollution at the source using a solid acid catalyst, achieving green production; and the synergistic effect of the bifunctional catalyst enabling "multi-purpose use of a single agent," effectively reducing production costs. This invention demonstrates significant advantages in product quality, process efficiency, economy, and environmental friendliness.

[0133] The embodiments described above merely illustrate more specific and detailed implementations of the present invention, and should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. The application of an epoxy-ring-opening bifunctional catalyst in the one-pot preparation of biomass polyols from methyl oleate via epoxy-ring-opening process, characterized in that, The epoxy-ring-opening bifunctional catalyst uses mesoporous molecular sieve SBA-15 as a support and simultaneously loads tungsten and molybdenum active metal components. The mesoporous molecular sieve SBA-15 is prepared by hydrothermal synthesis from silicon and aluminum sources. The silicon source is selected from tetraethyl silicate, tetramethyl silicate, or sodium silicate, and the aluminum source is selected from aluminum chloride or aluminum isopropoxide. The total loading of tungsten and molybdenum is 10 wt% of the mass of the silicon source, and the molar ratio of tungsten to molybdenum is (3:7) to (7:3). The mesoporous molecular sieve framework is doped with aluminum, and the silicon / alkalinity molar ratio of the framework is 10 to 30. The preparation method of the epoxy-ring-opening bifunctional catalyst includes the following steps: S1. Dissolve the template agent polyether P123 in deionized water, add acidic solution to adjust the pH of the mixed solution to 0.5~3, and stir at 40℃ for 1~6 hours; S2. Add silicon source and aluminum source to the mixed solution of step S1, and stir at 40°C for 0.5 to 2 hours to form a carrier precursor; then add molybdenum source and tungsten source, and continue stirring at 40°C for 12 to 36 hours to obtain a mixed solution precursor. S3. The mixed solution precursor obtained in step S2 is transferred to a hydrothermal reactor and hydrothermally treated at 80~120℃ for 24~72 hours. After hydrothermal treatment, it is filtered and washed with deionized water and dried at 70℃ for 12~24 hours to obtain the catalyst precursor. S4. The catalyst precursor obtained in step S3 is subjected to a heating and calcination process in air atmosphere: first, the temperature is increased to 200-400℃ at a rate of 2-20℃ / min and held for 0.5-2 hours; then, the temperature is increased to 450-650℃ at a rate of 2-20℃ / min and calcined for 4.5-6.5 hours to obtain the epoxy-ring-opening bifunctional catalyst.

2. The application according to claim 1, characterized in that, The application includes the following steps: (1) The vegetable oil, alkaline catalyst and methanol mixture was subjected to methyl esterification pretreatment at 50~100℃. After the reaction was carried out for 0.5~3h, an acidic reagent was added to terminate the reaction. The product was washed with water until neutral and then subjected to vacuum distillation to obtain methyl vegetable oil oleate, the raw material of the epoxy-ring-opening one-pot method. (2) The vegetable oleate methyl ester, epoxy-ring-opening bifunctional catalyst, deionized water and solvent are fully preheated in a container and stirred at a constant temperature of 100-300 rpm at 40-100℃ to obtain a mixture; (3) Add hydrogen peroxide solution dropwise to the mixture in step (2) and react at 40~100℃ for 4~24 hours to complete the epoxy-ring-opening one-pot reaction; (4) The mixed product prepared by the epoxy-ring-opening one-pot method is separated into liquids and washed with deionized water. The pH of the mixed product is washed to neutral, then dried and rotary distilled to obtain the biomass polyol.

3. The application according to claim 1, characterized in that, In step S1, the acidic solution is selected from one or more of hydrochloric acid, phosphoric acid, nitric acid, and fluoroboric acid. The pH of the mixed solution is adjusted to 1-1.5 by adding the acidic solution, and the mixture is stirred at 40°C for 2-4 hours. The mass ratio of polyether P123 to deionized water is 1:

30.

4. The application according to claim 1, characterized in that, In step S2, the molybdenum source is selected from one of ammonium molybdate, phosphomolybdic acid, or ammonium heptamolybdate; the tungsten source is selected from one of ammonium tungstate, ammonium metatungstate, or sodium tungstate; and the mass ratio of silicon source to polyether P123 is 9:

4.

5. The application according to claim 1, characterized in that, In step S4, the heating and calcination process is as follows: heat to 300°C at a rate of 5~10°C / min and hold for 0.5 hours, then heat to 550°C at a rate of 5~10°C / min and hold for 5.5 hours.

6. The application according to claim 2, characterized in that, In step (1), the vegetable oil is selected from tung oil, palm oil, soybean oil, castor oil, sunflower seed oil or camellia oil; the alkaline catalyst is selected from sodium hydroxide or potassium hydroxide; and the acidic reagent is selected from phosphoric acid, hydrochloric acid or nitric acid.

7. The application according to claim 2, characterized in that, In step (2), the amount of epoxy-ring-opening bifunctional catalyst added is 4-5 wt% of the mass of methyl oleate, the amount of deionized water added is 30-50 wt% of the mass of methyl oleate, and the solvent is selected from ethyl acetate, tetrahydrofuran or trimethylamine dihydrate, with the amount of solvent added being 100-300 wt% of the mass of methyl oleate.

8. The application according to claim 2, characterized in that, In step (3), the reaction temperature of the epoxy-ring-opening one-pot method is 50~80℃, and the reaction time is 8~12 hours; the concentration of the hydrogen peroxide solution is 30%, and the dropping acceleration rate is 0.01~0.015mL / s.

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