Epoxy-ring-opening bifunctional catalyst as well as preparation method and application thereof

Abstract

The invention discloses an epoxy-ring-opening bifunctional catalyst and a preparation method and application thereof, and belongs to the technical field of catalyst materials and biomass chemical engineering, the catalyst takes a mesoporous molecular sieve SBA-15 as a carrier, tungsten and molybdenum active components are combined with an aluminum-doped silicon-based framework through co-assembly and a hydrothermal method, and the mesoporous molecular sieve SBA-15 is prepared into the epoxy-ring-opening bifunctional catalyst. The total loading amount of tungsten and molybdenum is 10wt% of the mass of a 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 method comprises the following steps: self-assembly of a template agent, co-hydrolysis of a silicon-aluminum source and a tungsten-molybdenum source, hydrothermal crystallization, temperature programming calcination and the like. The catalyst is applied to preparation of biomass polyol from methyl vegetable oleate by one-pot epoxy-ring opening, and epoxidation and ring opening reactions are simultaneously realized under mild conditions. The polyol obtained by the invention has the characteristics of low viscosity, low acid value and high hydroxyl value.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalyst materials and biomass chemical technology, and particularly relates to an epoxy-ring-opening bifunctional catalyst and a preparation method and application thereof. BACKGROUND

[0002] With the increasing emphasis on sustainable development and green chemical industry worldwide, developing and utilizing renewable biomass resources to replace traditional fossil resources has become an important direction for the scientific research and industrial communities. Among them, vegetable oil is considered as an ideal platform compound for the preparation of bio-based chemicals and materials due to its wide source, low price and strong molecular structure modification. Especially, through chemical modification, vegetable oil is converted into polyols to partially or completely replace petroleum-based polyether polyols for polyurethane synthesis, which has extremely great economic and environmental value.

[0003] Currently, in the technical path of preparing polyols from vegetable oil, the "epoxidation-ring opening" route based on the carbon-carbon double bond on the unsaturated fatty acid chain is one of the most fully researched and most potential application methods. This route usually consists of two independent steps: the first step is epoxidation, i.e. in the presence of a catalyst, using an oxidizing agent (such as hydrogen peroxide) to convert the carbon-carbon double bond in vegetable oil into a more active epoxy group; the second step is ring opening, which makes the generated epoxy group react with water, alcohol, etc. under the action of an acid catalyst, thereby introducing the required hydroxyl functional group.

[0004] However, this traditional "two-step method" process has several bottlenecks that need to be solved. First, the process is long and complex, with high energy consumption. After the epoxidation reaction, the intermediate product, epoxy vegetable oil, must be subjected to tedious neutralization, washing and purification to remove residual catalyst and stabilize the product, after which the second step of ring opening reaction can be carried out, which significantly increases the operation 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, not only causing resource waste, but also generating a large amount of acidic wastewater and waste residues, causing serious environmental pressure and subsequent treatment costs. Thirdly, from the perspective of product quality, in the epoxidation system involving carboxylic acid, the side reaction of premature ring opening of epoxy groups under acidic conditions is prone to occur, resulting in high acid value, low target hydroxyl value, uneven functional group distribution of the final obtained polyol, and often large product viscosity, which is not conducive to subsequent storage, transportation and polyurethane synthesis processing.

[0005] Therefore, the application provides an epoxy-opening bifunctional catalyst, a preparation method and application thereof, a porous composite catalyst material with a transition metal epoxy active center and a solid acid ring-opening active center is designed and constructed, under mild conditions without additional carboxylic acid, a cascade one-pot reaction of epoxy-opening is realized by taking vegetable oil acid methyl ester as a raw material, so that the comprehensive goals of simplifying a process flow, reducing energy consumption and three waste emissions, improving atomic economy, and obtaining high-quality biomass polyols with low acid value, low viscosity and high hydroxyl value are achieved. SUMMARY

[0006] The application aims to provide an epoxy-opening bifunctional catalyst, a preparation method and application thereof, and realize a cascade one-pot reaction of epoxy-opening by taking vegetable oil acid methyl ester as a raw material under mild conditions without additional carboxylic acid.

[0007] The application is achieved by the following technical solutions. An epoxy-opening bifunctional catalyst, the catalyst takes mesoporous molecular sieve SBA-15 as a carrier and simultaneously loads tungsten (W) and molybdenum (Mo) active metal components; the mesoporous molecular sieve SBA-15 is prepared by a hydrothermal synthesis method from a silicon source and an aluminum source, wherein the silicon source is selected from one of tetraethyl silicate, tetramethyl silicate or sodium silicate, and the aluminum source is selected from one of aluminum chloride or aluminum isopropyl alcohol; wherein the total loading amount of tungsten and molybdenum is 10wt% of the mass of the silicon source (mW+mMo=10%mSi) in terms of metal mass, and the molar ratio of tungsten (W) to molybdenum (Mo) is (3:7)~(7:3); the mesoporous molecular sieve framework is doped with aluminum (Al), and the framework silicon aluminum molar ratio Si / Al is 10~30.

[0008] The application also claims to protect a preparation method of the above-mentioned epoxy-opening bifunctional catalyst, comprising the following steps: S1, dissolving a template agent polyether P123 in deionized water, adding an acidic solution to adjust the pH of the mixed solution to 0.5~3, and stirring at 40℃ for 1~6 hours; S2, adding a silicon source and an aluminum source to the mixed solution of step S1, stirring at 40℃ for 0.5~2 hours to form a carrier precursor; then adding a molybdenum source and a tungsten source, and continuing to stir at 40℃ for 12~36 hours to obtain a mixed solution precursor; S3, transferring the mixed solution precursor obtained in step S2 to a hydrothermal reaction kettle, and hydrothermally treating at 80~120℃ for 24~72 hours; after the hydrothermal treatment, filtering and washing with deionized water, and drying at 70℃ for 12~24 hours to obtain a catalyst precursor; S4, the catalyst precursor obtained in step S3 is subjected to a temperature rising calcination procedure in an air atmosphere: first, the temperature is raised to 200-400°C at a rate of 2-20°C / min, and maintained for 0.5-2 hours; then, the temperature is raised to 450-650°C at a rate of 2-20°C / min, and calcination is continued for 4.5-6.5 hours, to obtain the epoxy-ring-opening bifunctional catalyst.

[0009] Preferably, in step S1, the acidic solution is selected from one or more of hydrochloric acid, phosphoric acid, nitric acid, and fluoroboric acid, and the addition of the acidic solution adjusts the pH of the mixed solution to 1-1.5, and stirring is performed at 40°C for 2-4 hours; the mass ratio of the polyether P123 to deionized water is 1:30.

[0010] 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 the polyether P123 is 9:4.

[0011] Preferably, in step S3, the temperature of the hydrothermal treatment is 100°C, and the hydrothermal time is 24 hours.

[0012] Preferably, in step S4, the temperature rising calcination procedure is: the temperature is raised to 300°C at a rate of 5-10°C / min, and maintained for 0.5 hours; then, the temperature is raised to 550°C at a rate of 5-10°C / min, and maintained for 5.5 hours.

[0013] The present application also claims protection for an application of the above-mentioned epoxy-ring-opening bifunctional catalyst in catalyzing the one-pot epoxy-ring-opening preparation of biomass polyols from methyl plant oil acid.

[0014] Preferably, the application comprises the following steps: (1) the mixture of plant oil, base catalyst, and methanol is subjected to methyl esterification pretreatment at 50-100°C, and after reaction for 0.5-3 hours, an acidic reagent is added to terminate the reaction, the product is washed with water until neutral, and vacuum distillation is performed, to obtain the raw material methyl plant oil acid for the one-pot epoxy-ring-opening reaction; (2) the methyl plant oil acid, bifunctional catalyst, deionized water, and solvent are preheated in a container, and constant temperature stirring is performed at 40-100°C at a stirring rate of 100-300 rpm, to obtain a mixture; (3) hydrogen peroxide solution is added dropwise to the mixture of step (2), and reaction is performed at 40-100°C for 4-24 hours, to complete the one-pot epoxy-ring-opening reaction; (4) the mixed product prepared by the epoxy-ring opening one-pot method is subjected to liquid separation and water washing with ionized water, the mixed product is washed to neutral pH, and then dried and rotary evaporated to obtain the biomass polyol.

[0015] Preferably, in step (1), the plant oil is selected from one of tung oil, palm oil, soybean oil, castor oil, sunflower seed oil or camellia oil; the base catalyst is selected from one of sodium hydroxide and potassium hydroxide; and the acidic reagent is selected from one of phosphoric acid, hydrochloric acid and nitric acid.

[0016] Preferably, in step (1), the reaction temperature of the methyl esterification pretreatment is 70±5℃, and the reaction time is 1-1.5 h.

[0017] Preferably, in step (2), the addition amount of the bifunctional catalyst is 4-5 wt% of the mass of the methyl ester of plant oil, the addition amount of deionized water is 30-50 wt%, and the solvent is selected from one of ethyl acetate, tetrahydrofuran and trimethylamine dihydrate oxide, and the addition amount is 100-300 wt%.

[0018] Preferably, in step (2), the mixture is obtained by constant temperature stirring at 50-80℃ and a stirring rate of 200 rpm.

[0019] 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 0.01-0.015 mL / s.

[0020] Working mechanism of the present application: the epoxy-ring opening bifunctional catalyst provided by the present application realizes a complete cascade catalytic process from epoxidation to ring opening through its ingenious composition and structural design. The catalyst takes ordered mesoporous molecular sieve SBA-15 as a carrier, and its unique pore structure provides sufficient mass transfer channels and reaction sites for reactant molecules. In the initial stage of the reaction, the tungsten and molybdenum transition metal active sites loaded on the surface of the catalyst react with hydrogen peroxide to generate metal peroxide species (M-O-O-H) in situ, which have high oxidation activity. These active species preferentially attack the carbon-carbon double bond in the long chain of the methyl ester of plant oil, and selectively convert it into an epoxy group through an efficient oxygen atom transfer mechanism to form an intermediate of the epoxy methyl ester of plant oil.

[0021] With the progress of the epoxidation reaction, the bifunctional acid center produced by aluminum doping in the catalyst begins to play a key role. On the one hand, the Si-OH-Al structure in the skeleton provides a Brønsted acid site to release protons to activate the epoxy group; on the other hand, the unsaturated coordinated Al³⁺ and other metal species provide Lewis acid sites to enhance the electrophilicity of the epoxy group through the electronic effect. Under the synergistic effect of the dual acid center, water molecules in the reaction system act as a green ring-opening agent to initiate a nucleophilic attack on the activated epoxy group, promoting the ring-opening of the epoxy ring and generating the corresponding vicinal diol structure, successfully introducing a hydroxyl functional group on the molecular chain.

[0022] The close spatial arrangement and synergistic effect of this bifunctional active center ensure that the intermediates generated by the epoxidation reaction can undergo ring-opening reaction at the adjacent acid sites without long-range diffusion, forming an efficient "reaction-transfer" continuous process. The whole process is carried out under mild conditions without the need for additional carboxylic acid catalysts, not only avoiding the problems of side reactions and epoxy group ring-opening isomerization caused by excessive acidity in traditional processes, but also significantly reducing the acid value and viscosity of the product. Ultimately, the process goal of one-pot efficient conversion of methyl oleate to high-quality biomass polyols is achieved, while reducing the emission of three wastes, embodying the core concept of green chemical engineering.

[0023] Due to the use of the above technical scheme, the present application has the following beneficial effects compared with the prior art: 1、The present application significantly reduces the viscosity of the product, improves the performance and application convenience of the product, and by methyl esterification pretreatment of vegetable oil to convert it into methyl oleate as the reaction raw material, the viscosity of the polyol product prepared therefrom is much lower than that of the product obtained by directly using the original vegetable oil; low viscosity not only significantly improves the mass transfer efficiency in the reaction system, increases the reaction rate of the "one-pot method", but also makes the final product more advantageous in storage, transportation and subsequent polyurethane synthesis process; 2、The present application realizes efficient "one-pot method" cascade reaction and simplifies the process flow, the bifunctional catalyst provided by the present application successfully integrates the active centers of epoxidation and ring-opening reactions into one, realizing "one-pot method" synthesis from raw materials to polyols; this completely solves the problems of complicated process flow, intermittent operation, high energy consumption and other problems existing in the traditional "two-step method", greatly simplifies the production steps and improves the production efficiency; 3、The present application has high atom economy and mild reaction conditions, in the reaction design, the by-product water generated after hydrogen peroxide participates in the epoxidation reaction can be directly used as a reagent for the next step of ring-opening reaction, realizing efficient utilization of reactants and high atom economy; at the same time, the whole cascade reaction can be carried out under mild temperature conditions, reducing energy consumption and process control difficulty; 4、The solid acid catalyst is adopted in the present application, and the use of the homogeneous inorganic acid or carboxylic acid catalyst in the traditional process is completely avoided; this not only solves the problem of high acid value of the product caused by the residual acid catalyst from the source, ensures the product quality, but also the catalyst is easy to recycle, greatly reduces the discharge and subsequent treatment cost of acid wastewater and waste residue, and meets the development requirements of green chemical industry; 5、The catalyst has dual functions of synergy, one dose serves multiple purposes, and the cost is low; the catalyst has metal active centers (W / Mo) and acid centers (from Al doping), and the two are closely adjacent in space, synergistically act, and ensure the high efficiency and high selectivity of the epoxy-ring opening cascade reaction. One catalyst replaces two (or more) catalysts in the traditional process, realizes "one dose serves multiple purposes", and reduces the use and management cost of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the specific embodiments or the prior art description will be briefly introduced. Obviously, some of the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0025] Figure 1 It is a scanning electron microscope image of 11WMO@Al-SBA-15 used in embodiment 1 of the present application, wherein figure a is a catalyst morphology structure image with magnification of 1000 times; figure b is a catalyst morphology and pore structure image with magnification of 10000 times; figure c is a catalyst morphology and pore structure image with magnification of 20000 times; figure d is a catalyst morphology and pore structure image with magnification of 50000 times; Figure 2 It is a biomass polyol FT-IR characterization analysis result comparison spectrum diagram of embodiment 2 and comparative example 1 prepared in the present application. DETAILED DESCRIPTION

[0026] In order to have a more clear understanding of the technical features, purposes and effects of the present application, the specific implementation schemes will be described in detail.

[0027] The present application will be further described below in combination with examples, but the present application is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to different requirements of specific use, and the implementation conditions marked are the conventional conditions in the industry. The technical features involved in each embodiment of the present application can be combined with each other as long as there is no conflict.

[0028] Synthesis Example 1 The present synthesis example provides a preparation method of an epoxy-ring opening dual functional catalyst, comprising the following steps: S1, 2.0 g of template agent polyether P123 was dissolved in 65 mL of deionized water, 20 mL of HCl solution with a concentration of 4 mol / L was added, and stirring was carried out at 40℃ for 2 h until P123 was completely dissolved; S2, 4.5 g of tetraethyl silicate, 0.44 g of aluminum isopropoxide was added to the mixed solution of step S1, stirring was carried out at 40℃ for 1 h, then 0.0558 g of ammonium molybdate, 0.0407 g of ammonium metatungstate was added, stirring was carried out at 40℃ for 24 h, and a mixed solution precursor was obtained; S3, the mixed solution precursor obtained in step S2 was transferred to a hydrothermal reaction kettle, hydrothermal treatment was carried out at 100℃ for 48 h, then deionized water was used for washing and filtration, and drying was carried out at 70℃ for 12 h; S4, the catalyst precursor after drying in step S3 was placed in a tube furnace, the temperature was increased to 300℃ at a rate of 10℃ / min in an air atmosphere, and the temperature was kept for 0.5 h, then the temperature was continuously increased to 550℃ at a rate of 10℃ / min, and calcination was carried out for 5.5 h, to obtain the epoxy- ring opening bifunctional catalyst, which was recorded as 11WMo@Al-SBA-15.

[0029] Synthesis Example 2 The synthesis example provides a preparation method of an epoxy-ring opening bifunctional catalyst, which comprises the following steps: S1, 2.0 g of template agent polyether P123 was dissolved in 65 mL of deionized water, 20 mL of HCl solution with a concentration of 4 mol / L was added, and stirring was carried out at 40℃ for 2 h until P123 was completely dissolved; S2, 4.5 g of tetraethyl silicate, 0.44 g of aluminum isopropoxide was added to the mixed solution of step S1, stirring was carried out at 40℃ for 1 h, then 0.0335 g of ammonium molybdate, 0.0569 g of ammonium metatungstate was added, stirring was carried out at 40℃ for 24 h; S3, the mixed solution precursor obtained in step S2 was transferred to a hydrothermal reaction kettle, hydrothermal treatment was carried out at 100℃ for 48 h, then deionized water was used for washing and filtration, and drying was carried out at 70℃ for 12 h; S4, the catalyst precursor after drying in step S3 was placed in a tube furnace, the temperature was increased to 300℃ at a rate of 10℃ / min in an air atmosphere, and the temperature was kept for 0.5 h, then the temperature was continuously increased to 550℃ at a rate of 10℃ / min, and calcination was carried out for 5.5 h, to obtain the epoxy- ring opening bifunctional catalyst, which was recorded as 73WMo@Al-SBA-15.

[0030] Synthesis Example 3 The synthesis example provides a preparation method of an epoxy-ring opening bifunctional catalyst, which comprises the following steps: S1, 2.0 g of template agent polyether P123 was dissolved in 65 mL of deionized water, 20 mL of 4 mol / L HCl solution was added, and the mixture was stirred at 40°C for 2 h until P123 was completely dissolved; S2, 4.5 g of tetraethyl silicate and 0.44 g of aluminum isopropoxide were added to the mixed solution of step S1, and the mixture was stirred at 40°C for 1 h. Then 0.0782 g of ammonium molybdate and 0.0244 g of ammonium metatungstate were added, and the mixture was stirred at 40°C for 24 h; S3, the mixed solution precursor obtained in step S2 was transferred to a hydrothermal reactor, and hydrothermal reaction was carried out at 100°C for 48 h. Then the product was washed with deionized water, filtered, and dried at 70°C for 12 h; S4, the dried catalyst precursor of step S3 was placed in a tube furnace, and the temperature was raised to 300°C at a rate of 10°C / min in air atmosphere, and maintained for 0.5 h. Then the temperature was raised to 550°C at a rate of 10°C / min, and calcination was carried out for 5.5 h to obtain the epoxy-ring opening bifunctional catalyst, which is denoted as 37WMo@Al-SBA-15.

[0031] The epoxy-ring opening bifunctional catalyst prepared in the above synthesis example was subjected to X-ray fluorescence spectrum analysis (XRF), and the detection results are shown in Table 1.

[0032] Table 1

[0033] Example 1 Referring to the accompanying Figure 1 , the present embodiment provides a use of an epoxy-ring opening bifunctional catalyst in catalyzing one-pot epoxy-ring opening preparation of biomass polyol from methyl plant oil acid, which comprises the following steps: (1) the mixture of plant oil, alkali catalyst and methanol was subjected to methyl esterification pretreatment at 70°C, and after reaction for 1.5 h, an acidic reagent was added to terminate the reaction. The product was washed with water to neutral, and subjected to vacuum distillation to obtain the raw material methyl plant oil acid for one-pot epoxy-ring opening reaction; (2) 10.0 g of methyl tung oil acid after methyl esterification, 5.0 g of deionized water, 0.3 g of bifunctional catalyst 11WMo@Al-SBA-15, and 25 g of ethyl acetate were added to a three-necked flask, and the mixture was heated and stirred in a water bath at 70°C, with a stirring rate of 200 rpm. The constant temperature stirring obtained a mixture; (3) 20.0 g of 30% hydrogen peroxide solution was added dropwise to the mixture of step (2) at a rate of 0.015 mL / s; constant temperature stirring reaction was carried out for 12 h to complete the one-pot epoxy-ring opening reaction; (4) The mixed product prepared by the epoxy-opening one-pot method is transferred to a separatory funnel, the upper liquid is taken, washed with ionized water, adjusted to neutral pH, and then placed in a rotary evaporator to obtain the final product, biomass polyol, under the conditions of 0.1 MPa vacuum and 70°C.

[0034] Example 2 Referring to the accompanying drawings, Figure 2 The present embodiment provides an application of an epoxy-opening bifunctional catalyst in catalyzing the one-pot epoxy-opening preparation of biomass polyol from methyl plant oil acid, including the following steps: (1) The mixed solution of plant oil, base catalyst and methanol is pretreated by methyl esterification at 70°C, and after 1.5 hours of reaction, an acidic reagent is added to terminate the reaction, the product is washed with water to neutral, and vacuum distillation is performed to obtain the raw material methyl plant oil acid for the epoxy-opening one-pot method; (2) 10.0 g of methyl tung oil acid, 5.0 g of deionized water, 0.3 g of the bifunctional catalyst 11WMo@Al-SBA-15, and 25 g of ethyl acetate are added to a three-necked flask, heated and stirred under water bath at 60°C, the stirring rate is 200 rpm, and the mixture is obtained by constant temperature stirring; (3) 20.0 g of 30% hydrogen peroxide solution is added dropwise to the mixture of step (2) at a rate of 0.015 mL / s; constant temperature stirring is performed for 12 hours to complete the epoxy-opening one-pot reaction; (4) The mixed product prepared by the epoxy-opening one-pot method is transferred to a separatory funnel, the upper liquid is taken, washed with ionized water, adjusted to neutral pH, and then placed in a rotary evaporator to obtain the final product, biomass polyol, under the conditions of 0.1 MPa vacuum and 70°C.

[0035] Example 3 The present embodiment provides an application of an epoxy-opening bifunctional catalyst in catalyzing the one-pot epoxy-opening preparation of biomass polyol from methyl plant oil acid, including the following steps: (1) The mixed solution of plant oil, base catalyst and methanol is pretreated by methyl esterification at 70°C, and after 1.5 hours of reaction, an acidic reagent is added to terminate the reaction, the product is washed with water to neutral, and vacuum distillation is performed to obtain the raw material methyl plant oil acid for the epoxy-opening one-pot method; (2) 10.0 g of methyl tung oil acid, 5.0 g of deionized water, 0.3 g of the bifunctional catalyst 11WMo@Al-SBA-15, and 25 g of ethyl acetate are added to a three-necked flask, heated and stirred under water bath at 60°C, the stirring rate is 200 rpm, and the mixture is obtained by constant temperature stirring; (3) 20.0 g of 30% hydrogen peroxide solution was added dropwise to the mixture of step (2) at a rate of 0.015 mL / s; the reaction was stirred at constant temperature for 12 h to complete the epoxy-ring opening one-pot reaction; (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 ionized water, and then placed in a rotary evaporator after being adjusted to neutral pH, to obtain the final product of biomass polyol under the conditions of a vacuum degree of 0.1 MPa and 70°C.

[0036] Example 4 The present example provides an application of an epoxy-ring opening bifunctional catalyst in catalyzing the one-pot epoxy-ring opening preparation of biomass polyol from methyl ester of plant oil acid, which comprises the following steps: (1) The mixed solution of plant oil, base catalyst and methanol was pretreated by methyl esterification at 70°C, and after 1.5 h of reaction, an acidic reagent was added to terminate the reaction, the product was washed with water to neutral, and vacuum distillation was performed to obtain the raw material of methyl ester of plant oil acid for the epoxy-ring opening one-pot method; (2) 10.0 g of methyl esterified tung oil acid, 5.0 g of deionized water, 0.3 g of the bifunctional catalyst 73WMo@Al-SBA-15, and 25 g of ethyl acetate were added to a three-necked flask, heated and stirred under water bath at 60°C, the stirring rate was 200 rpm, and a mixture was obtained by constant temperature stirring; (3) 20.0 g of 30% hydrogen peroxide solution was added dropwise to the mixture of step (2) at a rate of 0.015 mL / s; the reaction was stirred at constant temperature for 12 h to complete the epoxy-ring opening one-pot reaction; (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 ionized water, and then placed in a rotary evaporator after being adjusted to neutral pH, to obtain the final product of biomass polyol under the conditions of a vacuum degree of 0.1 MPa and 70°C.

[0037] Example 5 The present example provides an application of an epoxy-ring opening bifunctional catalyst in catalyzing the one-pot epoxy-ring opening preparation of biomass polyol from methyl ester of plant oil acid, which comprises the following steps: (1) The mixed solution of plant oil, base catalyst and methanol was pretreated by methyl esterification at 70°C, and after 1.5 h of reaction, an acidic reagent was added to terminate the reaction, the product was washed with water to neutral, and vacuum distillation was performed to obtain the raw material of methyl ester of plant oil acid for the epoxy-ring opening one-pot method; (2) 10.0 g of methyl esterified tung oil acid, 5.0 g of deionized water, 0.3 g of the bifunctional catalyst 73WMo@Al-SBA-15, and 25 g of ethyl acetate were added to a three-necked flask, heated and stirred under water bath at 60°C, the stirring rate was 200 rpm, and a mixture was obtained by constant temperature stirring; (3) 20.0 g of 30% hydrogen peroxide solution was added dropwise to the mixture of step (2) at a rate of 0.015 mL / s; the reaction was stirred at constant temperature for 12 h to complete the epoxy-ring opening one-pot reaction; (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 ionized water, and then placed in a rotary evaporator after being adjusted to neutral pH, to obtain the final product, biomass polyol, under the conditions of a vacuum degree of 0.1 MPa and 70°C.

[0038] Comparative Example 1 Referring to the accompanying Figure 2 The present embodiment provides an application of an epoxy-ring opening bifunctional catalyst in catalyzing the one-pot epoxy-ring opening preparation of biomass polyol from methyl plant oil acid, which comprises the following steps: (1) A mixed solution of plant oil, alkali catalyst and methanol was pretreated by methyl esterification at 70°C, and after 1.5 h of reaction, an acidic reagent was added to terminate the reaction, the product was washed with water to neutral, and then subjected to vacuum distillation to obtain methyl plant oil acid as the raw material for the epoxy-ring opening one-pot method; (2) 10.0 g of methyl esterified tung oil acid, 5.0 g of deionized water, 0.3 g of the bifunctional catalyst 11WMo@Al-SBA-15 and 25 g of ethyl acetate were added to a three-necked flask, heated and stirred in a water bath at 60°C, the stirring rate was 200 rpm, and a mixture was obtained by constant temperature stirring; (3) 20.0 g of 30% hydrogen peroxide solution was added dropwise to the mixture of step (2) at a rate of 0.015 mL / s; the reaction was stirred at constant temperature for 6 h to complete the epoxy-ring opening one-pot reaction; (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 ionized water, and then placed in a rotary evaporator after being adjusted to neutral pH, to obtain the final product, biomass polyol, under the conditions of a vacuum degree of 0.1 MPa and 70°C.

[0039] Comparative Example 2 (1) 30.0 g of raw tung oil, 6.0 g of formic acid, 5.0 g of deionized water and 0.15 g of 75% phosphoric acid were added to a three-necked flask, heated and stirred in a water bath at 60°C, the stirring rate was 200 rpm, and a mixture was obtained by constant temperature stirring; (2) 27.0 g of 30% hydrogen peroxide solution was added dropwise to the mixture of step (1) at a rate of 0.015 mL / s; after the reaction was stirred at constant temperature for 12 h, a mixed product was obtained; (3) The mixed product was transferred to a separatory funnel, the upper liquid was taken, washed with ionized water, and then placed in a rotary evaporator after being adjusted to neutral pH, to obtain the final product, biomass polyol, under the conditions of a vacuum degree of 0.1 MPa and 70°C.

[0040] The biomass polyols prepared in the above examples and comparative examples were detected, and the detection results are shown in Table 2.

[0041] Table 2

[0042] It can be seen from the detection results that the acid value and viscosity of the biomass polyols prepared by catalytic reaction with WMo@Al-SBA-15 as the catalyst (Examples 1-5) are obviously lower than those of the biomass polyols prepared with inorganic acid as the catalyst (Comparative Example 2), and the selectivity of double bond of the products obtained when the reaction time is 12h (Examples 1-5) is generally better than that of the reaction time of 6h (Comparative Example 1) when WMo@Al-SBA-15 is used as the catalyst.

[0043] The test method of the hydroxyl value is according to the method of GB / T12008.3-2009 Plastics - Polyethers - Part 3: Determination of hydroxyl number. The mg sample is dissolved in acylation reagent, reacted at 115℃ for 0.5h, the phenolphthalein-pyridine indicator is added, and the 0.5mol / L NaOH standard solution is titrated to light red color and 30s no fading is the reaction end point, and the volume V1 of the consumed NaOH standard solution is recorded. The volume of the consumed NaOH of the blank group is also recorded as V2, and the product hydroxyl value OHV (mgKOH / g) is calculated according to the following formula: Formula I; V2 is the volume of the consumed NaOH solution of the sample, mL; V1 is the volume of the consumed NaOH solution of the blank, mL; C is the concentration of the sodium hydroxide standard solution, mol / L; m is the mass of the sample, g; The acid value C of the tung oil-based polyol is determined according to GB / T12008.5-2010, the mg sample is dissolved in ethanol-tetrahydrofuran solvent, the phenolphthalein indicator is added, and the 0.02mol / L KOH-ethanol standard solution is titrated to light red color and 30s no fading is the reaction end point, and the volume N of the consumed KOH-ethanol standard solution is recorded. The product acid value C (mgKOH / g) is calculated according to the following formula: Formula II; A is the volume of the consumed KOH solution of the sample, mL; N is the concentration of the KOH-ethanol standard solution, mol / L; m is the mass of the sample, g; The final corrected hydroxyl value OHV1 of the sample is OHV+C; The determination method of the double bond conversion rate: according to the method of GB / T5532.3-2022 Determination of Iodine Value of Animal and Vegetable Fats and Oils, a certain mass of sample is dissolved in cyclohexane-glacial acetic acid (equal volume mixed) solvent, 25.00 mL of Weihua reagent is removed and added, 20 mL of potassium iodide solution is added, and the yellow color of iodine is titrated to near disappearance with calibrated sodium thiosulfate solution. Add a few drops of starch solution and continue titration until the blue color just disappears. The iodine value of the sample is calculated according to the formula: Formula II; Wherein: W - the iodine value of the sample, g / 100g; c - the concentration of sodium thiosulfate standard solution, mol / L; V1 - the volume of sodium thiosulfate solution consumed by the blank, mL; V2 - the volume of sodium thiosulfate solution consumed by the sample, mL; m - the mass of the sample, g; Double bond conversion rate (%) = 1 - (product polyol iodine value / reactant raw material iodine value) x 100%; The determination method of viscosity: using viscosity meter NDJ-5S to determine.

[0044] The determination method of infrared spectrum: using Spectrum3FT-MIR Fourier transform infrared spectrometer to test the spectrum of biomass polyol sample in the wavelength range of 600-4000 cm -1 .

[0045] The determination method of scanning electron microscope image: using Czech TESCAN MIRAL MS scanning electron microscope to scan the morphology and pore of the catalyst at 1000-50000 times.

[0046] Biomass polyols were prepared from Example 2 and Comparative Example 1, and the obtained products were named as T-Polyol-12h and T-Polyol-6h, respectively, and were characterized by FT-IR, and the obtained FT-IR spectra were as shown in Figure 2 , from top to bottom, respectively, were the infrared spectra of raw tung oil (TO), methyl tung oilate (TOME), product tung oil-based polyol (T-Polyol-6h) and tung oil-based polyol 1 (T-Polyol-12h). Among them, 3400 cm -1 belongs to the O-H stretching vibration peak in hydroxyl; 3012 cm -1 belongs to the C-H stretching vibration peak in carbon-carbon double bond; 991 cm-1 belongs to the C-H bending vibration peak of carbon-carbon conjugated double bond; 830 cm -1Characteristic absorption peak belonging to epoxy bond. By comparison, TOME and T-polyol-6h still retain the characteristic peak of carbon-carbon double bond (3012cm -1 , 991cm -1 ) after methyl esterification, while the double bond characteristic peak of T-polyol-12h disappears, and a clear -OH characteristic peak (3400cm -1 ) appears, proving that the tung oil-based polyol product after 6h reaction time is not completely epoxidized, and there are still carbon-carbon double bond functional groups, while after 12h one-pot epoxy-ring opening reaction, TOME has been completely converted to tung oil-based polyol; TOME and T-polyol-12h have no epoxy bond characteristic peak at 830cm -1 , proving that the one-pot method successfully realizes the epoxy reaction of carbon-carbon double bond in methyl ester of tung oil and the ring-opening reaction after epoxy.

[0047] In summary, the present application realizes the efficient and green preparation of plant oil-based polyol through the synergistic innovation of methyl esterification pretreatment and bifunctional catalyst. Its significant advantages are: significantly reducing the viscosity of the product, improving the performance and processing convenience of the product; simplifying the process flow through "one-pot" cascade reaction, improving production efficiency; using hydrogen peroxide reaction by-product water as ring-opening reagent, high atom economy; using solid acid catalyst to eliminate acid pollution from the source, realizing green production; the synergistic effect of the bifunctional catalyst realizes "one agent for multiple uses", effectively reducing production cost. The present application shows significant advantages in product quality, process efficiency, economy and environmental protection, etc.

[0048] The above-described embodiments only express the specific and detailed implementation of the present application, but should not be construed as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which are within the scope of protection of the present application. Therefore, the scope of protection of the present patent should be subject to the appended claims.

Claims

1. An epoxy-ring-opening bifunctional catalyst, characterized in that, The 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 of 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.

2. A method for preparing the epoxy-ring-opening bifunctional catalyst as described in claim 1, characterized in that, 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 in step S1, and stir at 40°C for 0.5 to 2 hours to form a carrier precursor; Then, a molybdenum source and a tungsten source were added, and the mixture was stirred 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.

3. The method for preparing the epoxy-ring-opening bifunctional catalyst according to claim 2, 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 method for preparing the epoxy-ring-opening bifunctional catalyst according to claim 2, characterized in that, 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.

5. The method for preparing the epoxy-ring-opening bifunctional catalyst according to claim 2, 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 of the epoxy-ring-opening bifunctional catalyst as described in claim 1 in the one-pot epoxy-ring-opening process of methyl oleate to prepare biomass polyols.

7. The application according to claim 6, characterized in that, 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, 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, and then dried and rotary distilled to obtain the biomass polyol.

8. The application according to claim 7, 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.

9. The application according to claim 7, characterized in that, 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, with an addition amount of 100-300 wt%.

10. The application according to claim 7, characterized in that, 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.

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