Method for preparing furan compound by catalyzing fructose by using pyrrolidone and sulfonyl co-modified polymer

Abstract

The invention discloses a method for preparing a furan compound by catalyzing fructose by using a pyrrolidone and sulfo co-modified polymer, which is characterized by comprising the following steps: adding sodium p-styrenesulfonate, N-vinyl pyrrolidone, divinyl benzene, azodiisobutyronitrile and N, N-dimethylformamide into a reaction kettle lining according to the mass ratio of 1: 2.34: 0.58: 0.086: 29.63 to carry out hydrothermal reaction; and after the reaction is finished, sequentially washing with methanol, a sulfuric acid solution and methanol for 5 times, drying at 80 DEG C for 24 hours, and grinding to obtain the catalyst. The mass ratio of the catalyst to fructose to absolute ethyl alcohol is 1: (0.4-4.5): (16-80), a catalytic reaction is carried out under heating and stirring conditions, and the product yield is measured and calculated. The method has the beneficial effects that the pyrrolidone and sulfonic acid group co-modified polymer prepared by a simple method is used as a catalyst for the first time, fructose is catalyzed in a green solvent of pure ethanol to prepare the furan compound, and the total yield of the furan compound is remarkably improved by the synergistic effect of pyrrolidone and sulfonic acid groups.

Description

Technical Field

[0001] The invention relates to a method for preparing furan compounds by utilizing pyrrolidone and sulfonic acid group co-modified polymer to catalyze fructose, and belongs to the field of biomass-based chemicals. Background Art

[0002] The utilization of biomass resources is an important path to achieving the dual carbon goals. Converting biomass into energy, materials, fertilizers, and high-value chemicals can gradually reduce the use of traditional fossil energy and promote the emergence of new technologies, new industries, new business forms, and new models. In the future, with the advancement of science and technology and the development of society, different types of biomass resources will inevitably play a more important role on a global scale. Current biomass resource technologies include direct combustion, anaerobic biogas production, sugar fermentation to produce bioethanol, oil extraction and biodiesel production, pyrolysis to produce bio-oil, and gasification to produce synthesis gas. Among them, converting biomass into high-quality fuels urgently needs to improve conversion efficiency, reduce costs, and minimize reaction steps and losses.

[0003] The conversion of biomass into high-quality liquid fuels primarily involves multiple reaction steps, including depolymerization, isomerization, dehydration, etherification, condensation, and oxidation. These steps are coupled to form an extremely complex reaction network. The conversion of fructose to 5-ethoxymethylfurfural (EMF) in ethanol involves only two reaction steps, dehydration and etherification, both catalyzed by Brønsted acids. Although this reaction achieves high yields, the low reaction rate for HMF etherification and significant side reactions limit overall reaction efficiency. The etherification rate of 5-hydroxymethylfurfural (HMF) is significantly lower than that of the fructose dehydration step, which not only limits reaction efficiency but also leads to HMF accumulation. Brønsted acids catalyze the decomposition of HMF to form byproducts such as levulinic acid. Furthermore, accumulated HMF exacerbates the condensation of sugars and intermediates to form humins. These factors interact in a complex interplay. For example, increasing the temperature or increasing the Brønsted acid content or strength can accelerate HMF etherification but also exacerbate side reactions. Lowering the temperature reduces reaction efficiency.

[0004] HMF is an important intermediate product in the preparation of EMF from fructose. Due to its active chemical properties, it is easy to decompose, condense, and hydrate under acidic or high temperature conditions to produce by-products such as humin and levulinic acid, which limits the yield and selectivity of the target product. Summary of the Invention

[0005] The purpose of this patent is to solve the bottleneck problem of easy degradation of products and dependence on high-boiling-point solvents during acid-catalyzed fructose dehydration, and to provide a method for preparing furan compounds from fructose using pyrrolidone and sulfonic acid co-modified polymers. This method not only significantly improves the yield of furan compounds prepared from fructose, but also reduces solvent costs.

[0006] A method for preparing furan compounds by catalyzing fructose using a pyrrolidone and sulfonic acid group co-modified polymer, the invention mainly includes: (1) Preparing a pyrrolidone and sulfonic acid co-modified polymer, comprising the following steps: Step 1, dissolving the monomer: add a certain volume of N,N-dimethylformamide to the polytetrafluoroethylene lining of the reactor, and add the weighed sodium p-styrene sulfonate to the solvent under stirring.

[0007] Step 2, adding comonomer: after sodium p-styrene sulfonate is completely dissolved, add N-vinyl pyrrolidone.

[0008] Step 3, introducing a cross-linking agent: after sodium p-styrene sulfonate and N-vinyl pyrrolidone are evenly mixed, divinylbenzene is added.

[0009] Step 4, adding initiator: after stirring for a certain period of time, add initiator azobisisobutyronitrile; Step 5, starting the reaction: continue stirring for a certain period of time, then remove the rotor and place the polytetrafluoroethylene liner into the reactor, and perform hydrothermal reaction at 100°C for 24 hours; Step 6, cleaning and drying the material: After the reaction is completed, the material is washed with methanol 5 times, washed with 1 mol / L sulfuric acid solution 5 times, and then washed with methanol 5 times, vacuum dried at 80°C for 24 hours, and the solid material is ground into powder to obtain a catalyst.

[0010] (2) Catalytic effect test of pyrrolidone and sulfonic acid co-modified polymers The above substances are added to a pressure-resistant bottle in a mass ratio of catalyst: fructose: anhydrous ethanol of 1: (0.4-4.5): (16-80) at a reaction temperature of 110°C to 130°C for 30-150 minutes. After the reaction, the sample is diluted, filtered, and placed into a vial. The furan compound content is determined by high-performance liquid chromatography equipped with a UV detector.

[0011] The beneficial effects of the present invention are: 1) reducing side reactions and improving the overall yield of furan compounds, namely, the solvent effect and coordination ability of pyrrolidone compounds can stabilize HMF and inhibit its side reactions; 2) sulfonic acid resins containing pyrrolidone show better catalytic performance in the reaction of fructose to EMF under relatively high temperature conditions; 3) the catalyst preparation method is simple and the required raw materials are inexpensive, which may have great commercial potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Transmission electron microscopy (TEM) image of catalyst 1.5VP / 0.64SPSS / 0.37DVB.

[0013] Figure 2TEM image of catalyst 3.2SPSS / 2DVB.

[0014] Figure 3 (a) Comparison of the catalytic performance of 1.5VP / 0.64SPSS / 0.37DVB and 3.2SPSS / 2DVB in fructose conversion at different temperatures; Comparison of the product yields of 1.5VP / 0.64SPSS / 0.37DVB and 3.2SPSS / 2DVB at (b) 110°C, (c) 120°C, and (d) 130°C.

[0015] Figure 4 (a) Comparison of fructose conversion efficiency of 1.5VP / 0.64SPSS / 0.37DVB and 3.2SPSS / 2DVB at 1 wt% fructose. (b) Effect of fructose dosage and (c) catalyst dosage on fructose conversion in ethanol. (d) Conversion of fructose to HMF in tetrahydrofuran (THF) solvent (reaction conditions: 45 mg fructose, 20 mg catalyst, 1 mL THF).

[0016] Figure 5 Comparison of the catalytic effects of catalyst 1.5VP / 0.64SPSS / 0.37DVB with those in existing literature. DETAILED DESCRIPTION

[0017] In order to facilitate understanding by those skilled in the art, the present invention is further illustrated below with reference to the examples, and the contents mentioned in the implementation manner are not intended to limit the present invention. Example 1

[0018] The present invention discloses a method for preparing furan compounds by catalyzing fructose using a pyrrolidone and sulfonic acid group co-modified polymer, comprising the following steps: (1) First, synthesize the pyrrolidone and sulfonic acid co-modified polymer catalyst: dissolve 0.64 g of sodium p-styrene sulfonate in 20 mL of N,N-dimethylformamide; add 1.5 g of N-vinylpyrrolidone after the sodium p-styrene sulfonate is completely dissolved, and stir at room temperature for 5 minutes; add 0.37 g of divinylbenzene, and stir at room temperature for 5 minutes; add 55 mg of azobisisobutyronitrile, and continue stirring for 20 minutes. Remove the rotor and place the polytetrafluoroethylene reactor liner in the reactor; hydrothermal reaction at 100 ° C for 24 hours; after the reaction is completed, wash the material with methanol 5 times, wash it with 1 mol per liter sulfuric acid solution 5 times, and then wash it with methanol 5 times, and vacuum dry it at 80 ° C for 24 hours. Grind the solid material into powder to obtain the catalyst, which is named 1.5VP / 0.64SPSS / 0.37DVB.

[0019] (2) Comparative catalyst 1: sulfonated resin. The preparation process of sulfonated resin is as follows: add 19.6 ml of tetrahydrofuran and 4.5 ml of water to the polytetrafluoroethylene liner, stir evenly, add 2 g of divinylbenzene, add 3.2 g of sodium p-styrenesulfonate, add 0.055 g of azobisisobutyronitrile, cover with a lid, stir magnetically at room temperature, 100 degrees Celsius, and hydrothermally react for 24 hours; after the reaction is completed, wash the material with methanol 5 times, wash it with 1 mol per liter sulfuric acid solution 5 times, and then wash it with methanol 5 times, vacuum dry it at 80 degrees Celsius for 24 hours, and finally grind the solid material into powder, which is the catalyst, named 3.2SPSS / 2DVB.

[0020] (3) Comparative catalyst 2: 0.64 g of sodium p-styrene sulfonate was dissolved in 20 mL of N,N-dimethylformamide; 1.87 g of divinylbenzene was added after the sodium p-styrene sulfonate was completely dissolved; 55 mg of azobisisobutyronitrile was added after stirring at room temperature for 5 minutes; stirring was continued for 20 minutes, the rotor was removed and the polytetrafluoroethylene reactor liner was placed in the reactor; hydrothermal reaction was carried out at 100°C for 24 hours; after the reaction was completed, the material was washed with methanol 5 times, washed with 1 mol / L sulfuric acid solution 5 times, and then washed with methanol 5 times, and vacuum dried at 80°C for 24 hours. Finally, the solid material was ground into powder, which was the catalyst, named 0.64SPSS / 1.87DVB.

[0021] (4) Comparative catalyst 3: Amberlyst-15 is a widely used commercial catalyst purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0022] (5) Reaction system: 20 mg of catalyst (1.5VP / 0.64SPSS / 0.37DVB, 3.2SPSS / 2DVB, 0.64SPSS / 1.87DVB, Amberlyst-15), 1 mL of anhydrous ethanol, fructose concentration of 4.5%, reaction temperatures of 110°C, 120°C, and 130°C, and reaction times of 30, 60, 90, 120, and 150 min.

[0023] (6) After the reaction, the product was diluted 500-fold with water, filtered, and placed in a sample injection vial. 5-Ethoxymethylfurfural was determined by high-performance liquid chromatography equipped with a UV detector, the mobile phase was methanol:water 60:40 (Vt%), and the column temperature was 30°C. Fructose concentration was determined by high-performance liquid chromatography equipped with a parallax detector, the mobile phase was 5 mM H2SO4, and the column temperature was 30°C.

[0024] (7) The catalysts 1.5VP / 0.64SPSS / 0.37DVB and 3.2SPSS / 2DVB were characterized by TEM. Figure 1 and Figure 2 . (8) Since the product yields of 0.64SPSS / 1.87DVB and Amberlyst-15 were lower than those of the other two catalysts, the catalytic effects of 1.5VP / 0.64SPSS / 0.37DVB and 3.2SPSS / 2DVB at 110°C, 120°C, and 130°C were compared. The catalytic effects of 1.5VP / 0.64SPSS / 0.37DVB, 3.2SPSS / 2DVB, 0.64SPSS / 1.87DVB, and Amberlyst-15 were compared only at 130°C. Figure 3 .

[0025] At 110°C, the maximum EMF yield of 3.2SPSS / 2DVB within 90 minutes was 64.8%. In comparison, the maximum EMF yield of 1.5VP / 0.64SPSS / 0.37DVB was 49.5%. However, the total HMF / EMF yields of both catalysts were around 74%. At 120°C, the maximum EMF yields of 1.5VP / 0.64SPSS / 0.37DVB and 3.2SPSS / 2DVB were 62.3% and 67.5%, respectively. However, the total HMF / EMF yield of 1.5VP / 0.64SPSS / 0.37DVB, 78.1%, was higher than that of 3.2SPSS / 2DVB, 74.4%. When the temperature was increased to 130°C, the maximum EMF yields of 1.5VP / 0.64SPSS / 0.37DVB and 69.3%, respectively, were achieved, with the total HMF / EMF yield of 3.2SPSS / 2DVB increasing to 79.1%. Catalyst 3.2SPSS / 2DVB reached its peak yield sooner, but both HMF and EMF declined rapidly over time, particularly at relatively high temperatures. The pyrrolidone-containing catalyst 1.5VP / 0.64SPSS / 0.37DVB of the present invention, while reaching its peak yield slightly later, exhibited a greater advantage at higher temperatures, maintaining stable HMF and EMF in the reaction system over time under high-temperature conditions. Example 2

[0026] The present invention discloses a method for preparing furan compounds by catalyzing fructose using a pyrrolidone and sulfonic acid group co-modified polymer, comprising the following steps: (1) First, synthesize the pyrrolidone and sulfonic acid co-modified polymer catalyst: dissolve 0.64 g of sodium p-styrene sulfonate in 20 mL of N,N-dimethylformamide; add 1.5 g of N-vinylpyrrolidone after the sodium p-styrene sulfonate is completely dissolved, and stir at room temperature for 5 minutes; add 0.37 g of divinylbenzene, and stir at room temperature for 5 minutes; add 55 mg of azobisisobutyronitrile, and continue stirring for 20 minutes. Remove the rotor and place the polytetrafluoroethylene reactor liner in the reactor; hydrothermal reaction at 100 ° C for 24 hours; after the reaction is completed, wash the material with methanol 5 times, wash it with 1 mol per liter sulfuric acid solution 5 times, and then wash it with methanol 5 times, and vacuum dry it at 80 ° C for 24 hours. Grind the solid material into powder to obtain the catalyst, which is named 1.5VP / 0.64SPSS / 0.37DVB.

[0027] (2) Reaction system: 10 mg, 15 mg, 20 mg, 25 mg of catalyst (1.5 VP / 0.64 SPSS / 0.37 DVB); 1 mL of anhydrous ethanol; 10 mg, 25 mg, 45 mg, 65 mg, 90 mg of fructose; reaction temperature 130 ° C, reaction time 20-80 minutes.

[0028] (3) After the reaction, the product was diluted 500-fold with water, filtered, and placed in a sample vial. 5-Ethoxymethylfurfural was determined by high-performance liquid chromatography equipped with a UV detector, the mobile phase was methanol:water 60:40 (Vt%), and the column temperature was 30°C. Fructose concentration was determined by high-performance liquid chromatography equipped with a parallax detector, the mobile phase was 5 mM H2SO4, and the column temperature was 30°C.

[0029] (5) In order to further improve the yield of furan compounds, the reaction conditions were optimized. The catalytic effects of 1.5VP / 0.64SPSS / 0.37DVB and 3.2SPSS / 2DVB were shown in Figure 2. Figure 4 .

[0030] The best reaction system was 10 mg of fructose, 15 mg of catalyst, 1 mL of ethanol, and a reaction time of 40 minutes at 130°C, achieving an EMF yield of 81.9% and an HMF yield of 10.8%, for a combined HMF and EMF yield of 92.7%. This system can be used to produce furan compounds in a continuous flow reactor.

[0031] (6) The best catalytic effect of 1.5VP / 0.64SPSS / 0.37DVB in ethanol was compared with the existing literature, see Figure 5 .

Claims

1. A method for preparing furan compounds by catalyzing fructose with pyrrolidone and sulfonic acid group co-modified polymer, characterized in that: Sodium p-styrenesulfonate, N-vinylpyrrolidone and divinylbenzene were used as raw materials to synthesize pyrrolidone and sulfonic acid co-modified polymers. Pyrrolidone and sulfonic acid co-modified polymers were used to efficiently catalyze fructose to prepare furan compounds in an ethanol solvent. The mass ratio of catalyst: fructose: anhydrous ethanol was 1: (0.4-4.5): (16-80), the reaction temperature was 110°C-130°C, and the reaction time was 30-150 minutes.

2. A method for preparing furan compounds from fructose using pyrrolidone and sulfonic acid group co-modified polymer as catalyzed by claim 1, characterized in that: The synthesis steps of sulfonated polymer containing pyrrolidone are as follows: Step 1, dissolving the monomer: add a certain volume of N,N-dimethylformamide to the polytetrafluoroethylene lining of the reactor, and add the weighed sodium p-styrene sulfonate to the solvent under stirring; Step 2, adding comonomer: after sodium p-styrene sulfonate is completely dissolved, add N-vinyl pyrrolidone; Step 3, introducing a crosslinking agent: after sodium p-styrene sulfonate and N-vinyl pyrrolidone are mixed, divinylbenzene is added; Step 4, adding initiator: after stirring for a certain period of time, add initiator azobisisobutyronitrile; Step 5, starting the reaction: continue stirring for a certain period of time, then remove the rotor and place the polytetrafluoroethylene liner into the reactor, and perform hydrothermal reaction at 100°C for 24 hours; Step 6, cleaning and drying the material: After the reaction is completed, the material is washed with methanol 5 times, washed with 1 mol / L sulfuric acid solution 5 times, and then washed with methanol 5 times, vacuum dried at 80 degrees Celsius for 24 hours, and finally ground into powder to obtain the catalyst.

3. The method for preparing furan compounds by catalyzing fructose with pyrrolidone and sulfonic acid group co-modified polymer as claimed in claim 1, characterized in that: The mass ratio of sodium p-styrenesulfonate: the mass of N-vinylpyrrolidone: the mass of divinylbenzene: the mass of azobisisobutyronitrile: the mass ratio of N,N-dimethylformamide is 1:2.34:0.58:0.086:29.63.

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