CN109824632B - Method for preparing 5-methylfurfural by using biomass carbohydrate - Google Patents

Abstract

The invention relates to a method for preparing 5-methylfurfural by using biomass carbohydrate, which comprises the following steps: sequentially adding biomass carbohydrate, tungsten carbide, distilled water, hydroiodic acid or elemental iodine and an organic solvent into a reaction kettle, stirring and reacting for 15-180 min at 90-200 ℃ in a hydrogen atmosphere of 50-500 psi, cooling in an ice water bath, separating a reaction solution, separating an upper organic phase, and further purifying to obtain the 5-methylfurfural. The raw material for preparing the 5-methylfurfural mainly comes from renewable biomass carbohydrate; the method uses the cheap and recyclable tungsten carbide catalyst, is carried out under mild reaction conditions, reduces the production cost, has low requirements on production equipment, and conforms to the principle of safe production.

Description

A kind of method utilizing biomass carbohydrate to prepare 5-methylfurfural

technical field

The invention belongs to the field of biomass catalytic conversion methods and compound synthesis methods, and in particular relates to a method for preparing 5-methylfurfural by using biomass carbohydrates.

Background technique

Biomass resources are considered to be the best choice to replace fossil resources, and the comprehensive and effective utilization of biomass is one of the effective means for green chemical technology to ensure the sustainable development of human beings. 5-Methylfurfural is an important fine chemical, widely used in medicine, pesticide, cosmetics and other industries, and is also an important component of general food flavors, and is even considered as an important anticancer drug; in addition, It can also serve as an important intermediate for renewable fuels (high-quality diesel, 2,5-dimethylfuran, etc.). Industrially, 5-methylfurfural is mainly prepared by reacting 5-methylfuran with expensive and highly toxic phosphorus oxychloride or phosgene (J.Org.Chem.1957, 22, 1268-1269). As early as 1934, it was reported that 5-methylfurfural could be prepared by reacting sucrose with hydrochloric acid and then treated with stannous chloride, but the whole process lasted 24 hours, and the final yield of 5-methylfurfural did not exceed 7 % (Org. Synth. 1934, 14, 62). Books such as "Handbook of Food Additives, Third Edition" also mention that 5-methylfurfural can be obtained by co-distilling various methylpentose sugars and acids, but no specific reaction parameters and results are given. However, the Chinese patent CN201210288559.X reports that fructo-based biomass is mixed with an acidic catalyst to selectively obtain 5-methylfurfural by rapid pyrolysis, and the pyrolysis time does not exceed 1min, but the yield of 5-methylfurfural is also relatively low , up to 21%. In recent years, the Chinese patent CN201410302966.0 discloses a catalyst in which noble metals such as ruthenium and palladium are supported on acidic montmorillonite in the presence of sodium iodide, and reacted at 130°C for 16 hours to catalyze the preparation of 5-methylfurfural from 5-hydroxymethylfurfural. Furfural (90.9% yield). Elad Meller etc. reported that 5-chloromethylfurfural or 5-bromomethylfurfural was used as a substrate, and the yield of 5-methylfurfural was about 99% (RSC Adv. , 2016, 6, 103149-103159). The above-mentioned 5-hydroxymethylfurfural, 5-chloromethylfurfural and 5-bromomethylfurfural can all be obtained from biomass sugar compounds (such as fructose, glucose, sucrose, cellulose, etc.), these studies are based on them 5-methylfurfural was obtained from the product, and the yields were high, but the reaction time was relatively long. However, a method reported in the literature is a method for one-step conversion of biomass carbohydrates to prepare 5-methylfurfural in a benzene/water two-phase solvent, Pd/C or RuCl ₃ , HI, and H ₂ system. Fructose and other carbohydrates are produced by HI 5-Methylfurfural and I ₂ , and I ₂ is reduced under the action of catalyst and H ₂ to generate HI to continue to participate in the conversion of fructose, and the target product with a yield of 68% is obtained in less than 2 hours (Yang, W ., Sen, A., 2011. ChemSusChem 4, 349-352). However, during the reaction process, expensive metals are used to catalyze the in situ reduction of free iodine to hydrogen iodide, which increases the production cost. If cheap metals can be used to replace expensive metals, the production cost of this method can be effectively reduced to accelerate its industrialization. However, in this reaction system, it is difficult for cheap metals with hydrogenation activity to have a good catalytic effect because they cannot withstand acid attack. Therefore, searching for acid-resistant non-noble metal hydrogenation catalysts is the focus and difficulty of preparing 5-methylfurfural from carbohydrates such as fructose with the participation of hydroiodic acid.

Contents of the invention

In order to make up for the deficiencies in the preparation of 5-methylfurfural by catalytic conversion of biomass carbohydrates, such as cumbersome steps and the use of noble metal catalysts, the invention provides a method for preparing 5-methylfurfural by using biomass carbohydrates. Under the action of a cheap tungsten carbide catalyst, a method for synergistically catalytic conversion of biomass carbohydrates to prepare 5-methylfurfural:

The invention has the advantages of simplicity, high efficiency, low industrialization cost and easy industrialization. So far, the use of non-noble metal catalysts in conjunction with hydroiodic acid to convert biomass carbohydrates into 5-methylfurfural in one step has not been reported in domestic and foreign literature, and this research is of great significance.

The object of the present invention is achieved through the following technical solutions.

The invention provides a method for preparing 5-methylfurfural from biomass carbohydrates, comprising the following steps: sequentially adding biomass carbohydrates, tungsten carbide, distilled water, hydroiodic acid or elemental iodine, and an organic solvent into the In a glass bottle of 50-500psi, under the hydrogen atmosphere of 50-500psi, the reaction was stirred at 90-200°C for 15-180min, cooled in an ice-water bath, the reaction solution was separated, and the upper organic phase was separated. After further purification, 5- Methylfurfural.

Further, the phase of the tungsten carbide is one or more of W ₂ C, WC, WC ₂ and the like, among which the pure phase of WC is preferred.

Further, the tungsten carbide can be non-supported tungsten carbide catalysts with various shapes and structures; it can also be supported tungsten carbide catalysts supported on different supports.

Further, the amount of the tungsten carbide catalyst (measured by active components) is 0.1-30 wt% of the input biomass carbohydrate.

Further, the biomass carbohydrate is one or more of fructose, glucose, sucrose, inulin and the like.

Further, the organic solvent is a common solvent such as benzene, toluene, tetrahydrofuran, ether, etc., and the dosage is 0.1-10 times the volume of the distilled water used. When choosing a miscible solvent such as ether, tetrahydrofuran, an appropriate amount of saturated saline must be added.

Compared with the prior art, the present invention has the beneficial effect that the preparation of the biomass-based 5-methylfurfural of the present invention uses a cheap tungsten carbide catalyst, which greatly reduces the production cost.

detailed description

The present invention will be further described in detail below in conjunction with the examples.

Those skilled in the art will understand that the following examples are only for illustrating the present invention and should not be considered as limiting the scope of the present invention. If no specific technique or condition is indicated in the examples, it shall be carried out according to the technique or condition described in the literature in this field or according to the product specification. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that could be purchased.

Example 1.

Add 0.1804g of fructose, 30mg of tungsten carbide (WC), 0.4ml of hydroiodic acid with a mass fraction of 55-58%, 1.6ml of distilled water, 5ml of toluene, and Decane, and then put the quartz lining with the drug in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill the hydrogen to make the internal pressure 300psi, no leaks After degassing, place the reaction kettle in an oil bath at 130°C for 60 minutes of reaction. After fully cooling, ventilate, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis. The test results show that the molar yield of 5-methylfurfural is The rate is 61%.

Example 2.

Add 0.1803g of fructose, 30mg of tungsten carbide (WC), 0.4ml of hydroiodic acid with a mass fraction of 55-58%, 1.6ml of distilled water, 8ml of toluene, and Decane, and then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill the hydrogen to make the internal pressure 200psi, no leak detection After degassing, place the reaction kettle in an oil bath at 130°C for 60 minutes of reaction. After fully cooling, ventilate, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis. The test results show that the molar yield of 5-methylfurfural is The rate is 63%.

Example 3.

In a 25ml quartz liner with a magnetic stirring bar, add 0.1804g fructose, 40mg tungsten carbide (WC), 0.5ml hydroiodic acid with a mass fraction of 55-58%, 1.5ml distilled water, 5ml toluene, known mass Decane, and then put the quartz lining with the drug in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill the hydrogen to make the internal pressure 300psi, no leaks After degassing, place the reaction kettle in an oil bath at 130°C for 60 minutes of reaction. After fully cooling, ventilate, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis. The test results show that the molar yield of 5-methylfurfural is The rate is 58%.

Example 4.

Add 0.1804g of fructose, 30mg of tungsten carbide (WC), 0.4ml of hydroiodic acid with a mass fraction of 55-58%, 1.6ml of distilled water, 5ml of toluene, and Decane, and then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill the hydrogen to make the internal pressure 200psi, no leak detection After degassing, place the reaction kettle in an oil bath at 130°C for 60 minutes of reaction. After fully cooling, ventilate, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis. The test results show that the molar yield of 5-methylfurfural is The rate is 62%.

Example 5.

In a 25ml quartz liner with a magnetic stirring bar, add 0.1803g fructose, 30mg tungsten carbide (WC), 0.4ml hydroiodic acid with a mass fraction of 55-58%, 1.6ml distilled water, 5ml toluene, known mass Decane, and then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill the hydrogen to make the internal pressure 200psi, no leak detection After degassing, place the reaction kettle in an oil bath at 130°C to react for 45 minutes. After fully cooling, ventilate, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis. The test results show that the molar yield of 5-methylfurfural is The rate is 58%.

Example 6.

In a 25ml quartz liner with a magnetic stirring bar, add 0.1797g glucose, 30mg tungsten carbide (WC), 0.4ml hydroiodic acid with a mass fraction of 55-58%, 1.6ml distilled water, 5ml toluene, and Decane, and then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill the hydrogen to make the internal pressure 200psi, no leak detection After degassing, place the reaction kettle in an oil bath at 160°C for 60 minutes of reaction. After fully cooling, ventilate, open the kettle, take the upper toluene phase and dilute it for gas chromatographic analysis. The test results show that the mass production of 5-methylfurfural is The rate is 20%.

Example 7.

Add 0.1802g sucrose, 30mg tungsten carbide (WC), 0.4ml hydroiodic acid with a mass fraction of 55-58%, 1.6ml distilled water, 5ml toluene, and Decane, and then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill the hydrogen to make the internal pressure 200psi, no leak detection After degassing, place the reaction kettle in an oil bath at 160°C for 60 minutes of reaction. After fully cooling, ventilate, open the kettle, take the upper toluene phase and dilute it for gas chromatographic analysis. The test results show that the mass production of 5-methylfurfural is The rate is 22%.

Example 8.

In a 25ml quartz liner with a magnetic stirring bar, add 0.1802g inulin, 30mg tungsten carbide (WC), 0.4ml hydroiodic acid with a mass fraction of 55-58%, 1.6ml distilled water, 5ml toluene, known mass decane, and then put the quartz lining with the drug in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill the hydrogen to make the internal pressure 200psi. After air leakage, place the reaction kettle in an oil bath at 160°C for 60 minutes. After cooling fully, ventilate, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis. The test results show that the quality of 5-methylfurfural is The yield was 30%.

Example 9.

In a 25ml quartz liner with a magnetic stirring bar, add 0.18g fructose, 12.3mg tungsten carbide (WC, the amount is equivalent to 6.3eq% of the amount of fructose added), 0.4ml hydriodic acid with a mass fraction of 55-58% , 1.6ml of distilled water, 5ml of toluene, and n-decane of known quality, then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and continue to fill Hydrogen, so that the internal pressure is 200psi, after detecting no air leakage, place the reactor in an oil bath at 130°C to react for 60min, after fully cooling, exhaust, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis , The detection result shows that the molar yield of 5-methylfurfural is 54%.

Comparative example 1.

In a 25ml quartz inner lining with a magnetic stirring bar, add 0.18g fructose, palladium charcoal (wherein the mass fraction of palladium is 5%, and the consumption is equivalent to 6.3eq% of the fructose addition), 0.4ml mass fraction is 55～ 58% hydroiodic acid, 1.6ml of distilled water, 5ml of toluene, n-decane of known quality, and then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, and replace the reactor with high-purity hydrogen Continue filling the hydrogen to make the internal pressure 200psi. After checking that there is no air leakage, put the reactor in an oil bath at 130°C for 60 minutes. After cooling down fully, exhaust, open the kettle, take the upper toluene phase and dilute it. Afterwards, gas chromatography analysis was carried out, and the detection result showed that the molar yield of 5-methylfurfural was 54%.

Comparative example 2.

In a 25ml quartz liner with a magnetic stirrer, add 0.18g fructose, molybdenum carbide (MoC, the amount is equivalent to 6.3eq% of the amount of fructose added), 0.4ml mass fraction of 55-58% hydroiodic acid, 1.6 ml of distilled water, 5ml of toluene, and n-decane of known quality, and then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill with hydrogen. Make the internal pressure 200psi, check that there is no air leakage, place the reaction kettle in an oil bath at 130°C for 60 minutes, fully cool, exhaust, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis, detection The results showed a molar yield of 44% for 5-methylfurfural.

Comparative example 3.

In a 25ml quartz inner lining with a magnetic stirring bar, add 0.18g fructose, nickel phosphide catalyst (amount equivalent to 6.3eq% of the amount of fructose added), 0.4ml mass fraction of 55-58% hydroiodic acid, 1.6 ml of distilled water, 5ml of toluene, and n-decane of known quality, and then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill with hydrogen. Make the internal pressure 200psi, check that there is no air leakage, place the reaction kettle in an oil bath at 130°C for 60 minutes, fully cool, exhaust, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis, detection The results showed a molar yield of 5-methylfurfural of 47%.

Comparative example 4.

In a 25m1 quartz lining with a magnetic stirrer, add 0.18g of fructose, iron phosphide catalyst (amount equivalent to 6.3eq% of the amount of fructose added), 0.4ml of hydriodic acid with a mass fraction of 55 to 58%, 1.6 ml of distilled water, 5ml of toluene, and n-decane of known quality, and then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill with hydrogen. Make the internal pressure 200psi, check that there is no air leakage, place the reaction kettle in an oil bath at 130°C for 60 minutes, fully cool, exhaust, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis, detection The results showed a molar yield of 5-methylfurfural of 41%.

Comparative example 5.

In the 25ml quartz lining with magnetic stirring bar, successively add 0.18g fructose, cobalt phosphide catalyst (consumption is equivalent to 6.3eq% of fructose adding amount), 0.4ml mass fraction is 55～58% hydroiodic acid, 1.6 ml of distilled water, 5ml of toluene, and n-decane of known quality, and then put the quartz lining with the medicine in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill with hydrogen. Make the internal pressure 200psi, check that there is no air leakage, place the reaction kettle in an oil bath at 130°C for 60 minutes, fully cool, exhaust, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis, detection The results showed a molar yield of 5-methylfurfural of 48%.

Comparative example 6.

Add 0.18g fructose, 0.4ml hydroiodic acid with a mass fraction of 55-58%, 1.6ml distilled water, 5ml toluene, and n-decane of known mass successively into a 25m1 quartz lining with a magnetic stirring bar, and then put the The quartz lining of the good medicine is placed in the high-pressure reactor, close the reactor, replace the air in the reactor with high-purity hydrogen, and then continue to fill the hydrogen to make the internal pressure 200psi. After checking that there is no air leakage, put the reactor in React in an oil bath at 130° C. for 60 minutes. After fully cooling, ventilate, open the kettle, take the upper toluene phase and dilute it for gas chromatography analysis. The test results show that the molar yield of 5-methylfurfural is 43%.

Table 1 below lists the catalytic activity comparison of tungsten carbide with palladium carbon and other common non-precious metals. As can be seen from Example 9 and Comparative Example 1, under the same conditions, cheap tungsten carbide is comparable to expensive palladium carbon catalyst activity; and from ratios 2 to 6, it can be seen that the common non-precious metals that often replace palladium carbon in many occasions The hydrogenation catalyst has no obvious effect on the formation of 5-methylfurfural in this system, indicating that the cheap metal catalysts that are not commonly used to replace platinum group noble metals can be better used in the reaction system for the preparation of 5-methylfurfural.

Table 1 Comparison of catalytic activity between tungsten carbide, palladium carbon and other common non-precious metals

catalyst type fructose dosage Catalyst equivalent to the amount of fructose 5-methylfurfural yield Example 9 Tungsten carbide (wC) 0.18g ≈6.3eq% 54% Comparative example 1 Palladium carbon 0.18g ≈6.3eq% 54% Comparative example 2 Molybdenum carbide (MoC) 0.18g ≈6.3eq% 44% Comparative example 3 Nickel Phosphide Catalyst 0.18g ≈6.3eq% 47% Comparative example 4 Iron phosphide catalyst 0.18g ≈6.3eq% 41% Comparative example 5 cobalt phosphide catalyst 0.18g ≈6.3eq% 48% Comparative example 6 No catalyst 0.18g 0% 43%

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and the description only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Variations and improvements all fall within the scope of the claimed invention. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (3)

1. A method for preparing 5-methylfurfural by using biomass carbohydrate is characterized by comprising the following steps: sequentially adding fructose, tungsten carbide, distilled water, hydroiodic acid and an organic solvent into a reaction kettle, stirring and reacting for 15 to 180min under the hydrogen atmosphere of 50 to 500psi and at the temperature of 90 to 200 ℃, cooling in an ice water bath, separating a reaction solution, separating an upper organic phase, and purifying to obtain 5-methylfurfural; the phase of the tungsten carbide is a pure phase of WC.

2. The method for preparing 5-methylfurfural from biomass carbohydrate as claimed in claim 1, wherein the amount of the tungsten carbide is 0.1 to 30wt% of the input fructose.

3. The method for preparing 5-methylfurfural from biomass carbohydrate as claimed in claim 1, wherein the organic solvent is benzene, toluene, tetrahydrofuran or diethyl ether, and the amount is 0.1-10 times of the volume of the distilled water.