Biomass dehydration method

Abstract

The invention relates to the field of biomass utilization, in particular to a biomass dehydration method. The method comprises the following step: in the presence of a solvent and in an inert atmosphere, carrying out contact reaction on biomass and an MWW molecular sieve. According to the method disclosed by the invention, the MWW molecular sieve is used for the dehydration reaction of the biomass to form an environment-friendly reaction system, so that the yield of a target dehydration product is increased, the generation of byproducts is reduced, the recycling rate of the catalyst is increased, and the requirements of industrial green production are met.

Description

Technical Field

[0001] The invention relates to the field of biomass utilization, and in particular to a method for dehydrating biomass. Background Art

[0002] With the over-exploitation and utilization of fossil fuels, the world is facing a severe energy crisis and environmental pollution. Biomass has the advantages of sustainability and wide sources, and the research on using it as raw material to synthesize energy and fine chemicals has become a hot topic in the field of biomass utilization.

[0003] 5-Hydroxymethylfurfural (HMF) is one of the important platform compounds released by the U.S. Department of Energy and plays an important role in the field of biomass energy. HMF molecules contain highly active furan rings, hydroxymethyl and aldehyde groups, which can be further transformed through hydrogenation, oxidative dehydrogenation, esterification, halogenation, polymerization, hydrolysis and other processes to synthesize a series of products with large markets and high added value. It is a monomer for the production of polymers and can also be used as a raw material to synthesize drug intermediates, antifungal agents, macrocyclic ligands and liquid fuels. Therefore, it is known as an important bridge compound connecting biomass chemical industry and petrochemical industry, and its synthesis has attracted extensive attention from researchers at home and abroad.

[0004] Acidic catalysts are commonly used catalysts for fructose dehydration to produce HMF, including inorganic acids, inorganic salts and solid acids, etc. Soluble inorganic acids are the cheapest acid catalysts, which often catalyze fructose dehydration in aqueous solution with high catalytic activity, but the generation of formic acid, levulinic acid and humin during the reaction is very serious.

[0005] CN113234043A reports a method for preparing and separating 5-hydroxymethylfurfural by dehydrating fructose, using p-toluenesulfonic acid, hydrochloric acid, etc. as catalysts. Although the reaction cost is reduced, there are problems such as difficulty in separating the product, severe equipment corrosion and environmental pollution.

[0006] Solid acid has the advantages of no corrosion to equipment, little pollution, and easy separation. CN103028424A reports a preparation method of a solid acid catalyst for the synthesis of 5-hydroxymethylfurfural, wherein the oxide is dissolved in deionized water, and a precipitant is used to precipitate it completely, and after aging, the precipitate is washed, filtered, and dried, and then the precipitate is immersed in a sulfuric acid solution or a chromium solution. After impregnation, the solid acid catalyst is roasted to obtain a solid acid catalyst for the synthesis of 5-hydroxymethylfurfural with a high yield. However, since the main active components of the catalyst are sulfate and chromium ions, a certain burden is imposed on the environment. CN101812039A provides a method for generating 5-hydroxymethylfurfural by catalysis of an ionic liquid, and the reaction belongs to a homogeneous catalytic reaction, with a small amount of catalyst added and a high yield. However, the reaction steps are cumbersome, and processes such as distillation are required. The selection of anions and cations of the ionic liquid catalyst is complicated, and organic reagents also bring a certain burden to the environment.

[0007] In summary, the existing methods for preparing 5-hydroxymethylfurfural have many by-products, low yield, high catalyst toxicity and difficulty in recovery. Therefore, it is necessary to find a suitable reaction system to improve the yield of 5-hydroxymethylfurfural, reduce the generation of by-products, and improve the recovery rate of the catalyst to meet the needs of green production. Summary of the invention

[0008] The purpose of the present invention is to overcome the problems of low biomass dehydration efficiency and low dehydration product selectivity in the prior art, and to provide a biomass dehydration method having high biomass dehydration efficiency and dehydration product selectivity.

[0009] In order to achieve the above object, the first aspect of the present invention provides a method for dehydrating biomass, which comprises: contacting and reacting biomass with MWW molecular sieve in the presence of a solvent and an inert atmosphere.

[0010] Through the above technical solution, the present invention has the following advantages:

[0011] The method of the present invention uses MWW molecular sieve for dehydration reaction of biomass to form an environmentally friendly reaction system, improves the yield of target dehydration products, reduces the generation of by-products, improves the recovery rate of catalysts, and meets the needs of industrial green production. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 yes Figure 1 H-SCM-1-SO in Example 1 3 XRD patterns of H and H-SCM-1 in Comparative Example 1;

[0013] Figure 2 H-SCM-1-SO in Example 1 3 H of N 2 - Adsorption-desorption curve;

[0014] Figure 3 H-SCM-1-SO in Example 1 3 py-FTIR pattern of H;

[0015] Figure 4 (a) H-SCM-1-SO in Example 1 3 Scanning electron microscopy (SEM) images of H;

[0016] Figure 5 H-SCM-1-SO in Example 1 3 Effect of H reaction time at 150℃ on the conversion of fructose to HMF. DETAILED DESCRIPTION

[0017] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0018] The invention provides a method for dehydrating biomass, which comprises: contacting and reacting biomass with MWW molecular sieve in the presence of a solvent and in an inert atmosphere.

[0019] The method of the present invention uses MWW molecular sieve for dehydration reaction of biomass to form an environmentally friendly reaction system, improves the yield of target dehydration products, reduces the generation of by-products, improves the recovery rate of catalysts, and meets the needs of industrial green production.

[0020] According to a preferred embodiment of the present invention, the biomass is selected from at least one of fructose, glucose, sucrose and maltose, preferably at least one of fructose and glucose.

[0021] According to a preferred embodiment of the present invention, the conditions of the contact reaction include: heating to a reaction temperature of 80-220°C, preferably 100-180°C, at a heating rate of 5°C / min-40°C / min, preferably 10°C / min-30°C / min.

[0022] According to a preferred embodiment of the present invention, the conditions of the contact reaction include: the reaction time is 10 min-20 h, preferably 20 min-200 min.

[0023] According to a preferred embodiment of the present invention, the conditions of the contact reaction include: the mass ratio of biomass to MWW molecular sieve is 1-50:1, preferably 1-20:1.

[0024] According to a preferred embodiment of the present invention, the conditions of the contact reaction include: the solvent includes water and an organic solvent.

[0025] According to a preferred embodiment of the present invention, the conditions of the contact reaction include: the organic solvent is selected from at least one of toluene, cyclohexane, dichloromethane, tetrahydrofuran, acetone and methyl isobutyl ketone.

[0026] According to a preferred embodiment of the present invention, the conditions of the contact reaction include: the volume ratio of the organic solvent to water is 4-20:1, preferably 6-10:1.

[0027] According to a preferred embodiment of the present invention, the conditions of the contact reaction include: the mass ratio of water to biomass is 1:0.01-2, preferably 1:0.2-1.2.

[0028] According to a preferred embodiment of the present invention, the method comprises: adding an organic solvent and a catalyst to a biomass aqueous solution, introducing an inert gas, heating the solution to a reaction temperature, cooling the solution after the reaction, and obtaining a biomass dehydration product.

[0029] According to a preferred embodiment of the present invention, the temperature is lowered to 10-25°C at a rate of 5°C / min-40°C / min, preferably at a rate of 10°C / min-30°C / min.

[0030] According to a preferred embodiment of the present invention, the inert atmosphere is at least one of a nitrogen atmosphere, an argon atmosphere and a helium atmosphere.

[0031] According to a preferred embodiment of the present invention, the MWW molecular sieve The ratio is 1.5-5.0, preferably 1.9-4.0. By adopting the above preferred embodiment, the yield of the target dehydration product can be further improved and the generation of by-products can be reduced.

[0032] According to a preferred embodiment of the present invention, the external specific area / total specific surface area of ​​the MWW molecular sieve is 0.2-0.9, preferably 0.3-0.7. By adopting the above preferred scheme, the yield of the target dehydration product can be further improved and the generation of by-products can be reduced.

[0033] According to a preferred embodiment of the present invention, the MWW molecular sieve is a sulfonate-modified MWW molecular sieve. By adopting the above preferred embodiment, the yield of the target dehydration product can be further improved and the generation of by-products can be reduced.

[0034] According to a preferred embodiment of the present invention, the sulfonate modification method comprises: acid elution of the hydrogen-type MWW molecular sieve, addition of a thiol compound, oxidation, and hydrothermal treatment.

[0035] According to a preferred embodiment of the present invention, the acid solution is at least one of hydrochloric acid, sulfuric acid and nitric acid, preferably hydrochloric acid.

[0036] According to a preferred embodiment of the present invention, the molar concentration of the acid solution is 0.5-10 mol / L, preferably 0.8-4 mol / L.

[0037] According to a preferred embodiment of the present invention, the mass ratio of the hydrogen-type MWW molecular sieve to the acid solution is 0.005-0.1, preferably 0.005-0.05.

[0038] According to a preferred embodiment of the present invention, the thiol compound is selected from at least one of mercaptoethanol, thioglycolic acid, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, dimethylmercaptopropionic acid, methyl mercaptopropionate, 1,3-dimercaptopropane, and 2,3-dimercapto-1-propanol, and is preferably at least one of mercaptoethanol, thioglycolic acid, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyltriethoxysilane.

[0039] According to a preferred embodiment of the present invention, the oxidizing agent is H 2 O 2 The amount used is not particularly limited as long as it can achieve complete oxidation.

[0040] According to a preferred embodiment of the present invention, the mass ratio of the mercapto compound to the hydrogen-type MWW molecular sieve is 0.005-2.0, preferably 0.5-1.0.

[0041] According to a preferred embodiment of the present invention, the molar ratio of the thiol compound to the oxidant is 0.001-1.0, preferably 0.005-0.5.

[0042] According to a preferred embodiment of the present invention, the oxidation conditions include: temperature of 5-40°C, preferably 10-25°C, and time of 3-24h, preferably 6-16h.

[0043] According to a preferred embodiment of the present invention, the conditions of the hydrothermal treatment include: a temperature of 50-180° C., preferably 70-130° C.; and a time of 3-40 h, preferably 6-15 h.

[0044] According to a preferred embodiment of the present invention, the sulfonate-modified MWW molecular sieve has a formula of "mSiO 2 nAl 2 O 3 pSO 3 H" shows a schematic chemical composition, wherein 20≤m / n≤66, 25≤m / p≤150, preferably, 22≤m / n≤60, 26≤m / p≤130; more preferably, 25≤m / n≤55, 28≤m / p≤100. By adopting the aforementioned preferred scheme, the yield of the target dehydration product can be further improved and the generation of by-products can be reduced.

[0045] According to a preferred embodiment of the present invention, the MWW molecular sieve is selected from at least one of SCM-1 molecular sieve, UZM-8 molecular sieve and MCM-56 molecular sieve, preferably SCM-1 molecular sieve. By adopting the above preferred scheme, the yield of the target dehydration product can be further improved and the generation of by-products can be reduced.

[0046] In the present invention, there is no special requirement for the preparation of the MWW molecular sieve. According to a preferred embodiment of the present invention, the preparation method of the MWW molecular sieve includes: mixing a silicon source, an aluminum source, an alkali source, an organic structure directing agent, dicyclohexylamine and water to obtain a mixture, and then crystallizing the mixture, performing a first washing, a first drying, a first calcination, an ammonium exchange and a second calcination to obtain a hydrogen-type MWW molecular sieve.

[0047] According to a preferred embodiment of the present invention, in the preparation method of MWW molecular sieve, the silicon source is SiO 2 Aluminum source is Al 2 O 3 The molar ratio of alkali source is OH-, organic structure directing agent, dicyclohexylamine and water is SiO 2 :Al 2 O 3 :OH-:Organic structure directing agent:Dicyclohexylamine:H 2 O=1: 0.015-0.050: 0.07-0.15: 0.20-0.30: 0.30-0.60: 14-30.

[0048] According to a preferred embodiment of the present invention, in the method for preparing MWW molecular sieve, the organic structure directing agent is hexamethyleneimine.

[0049] According to a preferred embodiment of the present invention, in the method for preparing MWW molecular sieve, the crystallization condition of the mixture is 130-170° C. for 1-7 days.

[0050] In the present invention, the reaction product 5-hydroxymethylfurfural is analyzed qualitatively and quantitatively by gas chromatography-mass spectrometry (GC-MS), and the conversion rate of the soluble carbohydrates in the product is analyzed by high performance liquid chromatography (HPLC). The gas chromatography-mass spectrometry instrument is Agilent 7890A of Agilent Corporation of the United States, the chromatographic column is HP-5 non-polar capillary column (30m, 0.53mm), the gas chromatograph is Agilent 7890B, the detector is a hydrogen flame ionization detector (FID), and the chromatographic column is SE-54 capillary column (30m, 0.53mm). The high performance liquid chromatography adopts Agilent 1200 analysis, and the chromatographic column is SHODEX SC1011 sugar column (8×300mm).

[0051] In the present invention, the mass fraction of the S element in the catalyst is measured by an inductively coupled plasma atomic emission spectrometer (ICP), model Varian 725-ES, and a physical adsorption instrument model Micromeretic ASAP2020M. The analysis sample is dissolved in hydrofluoric acid to detect the content of the element. After the mass fraction of the S element is obtained, -SO 3 H content.

[0052] In the present invention, the XRD measurement method of the catalyst is: using a Rigaku Ultima IV X-ray powder diffractometer from Japan to analyze the physical phase of the sample, and using a CuKα ray source. Nickel filter, 2θ scanning range 3°-75°, operating voltage 35KV, current 25mA, scanning rate 10° / min.

[0053] In the present invention, the scanning electron microscope (SEM) photos of the catalyst were taken on a Hitachi S-4800II scanning electron microscope. The acceleration voltage of the instrument was 15 kV, and the samples were chromium-plated before analysis.

[0054] In the present invention, the pyridine adsorption infrared (py-FTIR) method is used to determine the type of catalyst acid, and the py-FTIR spectrum is obtained on a Nicolet Model 710 spectrometer. The specific operation steps are as follows: a. Sample preparation and pretreatment, about 15 mg of sample is pressed into a thin disc with a diameter of 13 mm and loaded into an infrared sample tank; then the sample is pretreated at 120° C. for 2 hours in a vacuum cell. The sample is scanned at 100° C. to obtain a background spectrum. b. After the sample tank is cooled to room temperature, pyridine is adsorbed for 10 minutes. Vacuum desorption is performed at 100° C. for 10 minutes, and the infrared absorption spectrum is scanned and recorded. The difference spectrum before and after pyridine adsorption is the obtained Py-FTIR spectrum.

[0055] In the present invention, the test instrument and test method for the average pore size, specific surface area and pore volume of the sample are: physical adsorption measurement is performed by nitrogen at -196°C using a 3H-2000PM2 physical adsorption instrument to analyze the pore structure characteristics of each adsorption material sample. The initial degassing condition is: degassing operation at 150°C for 6 hours. After measuring the adsorption isotherm of nitrogen on the sample, the specific surface area is calculated using the BET (Brunauer-Emmett-Teller) method, and the pore volume and pore size distribution are calculated using the BJH (Barrett-Joyner-Halenda) method.

[0056] The present invention will be described in detail below through examples. However, the examples are only used to help understand the present invention and should not be regarded as specific limitations of the present invention. In the following examples, the raw materials are all commercially available; the relevant calculation formulas are as follows:

[0057] Fructose conversion rate (%) = (molar amount of fructose participating in the reaction) / (molar amount of fructose as the reaction substrate) × 100%.

[0058] The yield of the product 5-hydroxymethylfurfural (%) = (the molar amount of 5-hydroxymethylfurfural produced by the reaction) / (the molar amount of fructose reacted)×100%.

[0059] Example 1

[0060] Preparation of hydrogen-type MWW molecular sieve: deionized water, sodium aluminate (containing Al 2 O 3 40.5 wt%, Na 2 O 30.6 wt%), sodium hydroxide, hexamethyleneimine, dicyclohexylamine, silica sol (containing SiO 2 40.0 wt%) and stirred at room temperature for 3 hours to obtain a mixture. The final material ratio in molar ratio is:

[0061] SiO 2 / Al 2 O 3 =30;

[0062] NaOH / SiO 2 =0.09;

[0063] Hexamethyleneimine / SiO 2 =0.2

[0064] Dicyclohexylamine / SiO 2 =0.50

[0065] H 2 O / SiO 2 =18

[0066] The mixture was placed in a stainless steel reactor and heated for crystallization at 150°C and 150 rpm for 4 days. After crystallization, it was filtered, washed, dried in an oven at 100°C overnight, and calcined in air at 550°C for 6 hours to obtain the XRD spectrum of the sample. Figure 1 The molecular sieve shown in FIG. 1 is a molecular sieve with MWW structure. The SiO 2 / Al 2 O 3 The molar ratio is 29.5. The molecular sieve is ion exchanged and calcined to obtain the hydrogen-type SCM-1 molecular sieve.

[0067] The steps for preparing modified SCM-1 molecular sieve from hydrogen SCM-1 are as follows:

[0068] (1) Prepare a 2.0 M HCl solution, weigh 1 g of the hydrogen-type SCM-1 molecular sieve and disperse it in 100 g of hydrochloric acid. After stirring for 5 h, add 1.0 g of 3-mercaptopropyltrimethoxysilane dropwise. After continuing to stir for 20 min, add 1.8 g of hydrogen peroxide (30 wt %) dropwise, and then continue stirring at room temperature (20° C.) for 24 h.

[0069] (2) The stirred solution was placed in a crystallization reactor and reacted at 100°C for 10 hours.

[0070] (3) The crystallized liquid was washed with deionized water and ethanol several times until the upper clear liquid was neutral, and then dried at 80°C for 20 hours. Figure 1 As shown in the figure, the modified SCM-1 has the same characteristic peaks as the hydrogen-type SCM-1, but the peak intensity is reduced. The value of the external specific surface area / total specific surface area measured by BET is 0.37, N 2 -Absorption and desorption attached as shown Figure 2 As shown. ICP determination of S content, calculated SiO 2 / SO 3 The H molar ratio is 41.2. The infrared spectrum of pyridine is as follows Figure 3 As shown, The ratio is 2.7. Figure 4 As shown, the crystals are in the form of thin sheets with a crystal thickness of 6.2 nm.

[0071] Example 2

[0072] The steps for preparing modified UZM-8 molecular sieve from hydrogen-type UZM-8 with a silicon-aluminum ratio (molecular ratio) of 30 are as follows:

[0073] (1) Prepare a 2.0 M HCl solution, weigh 1 g of the above hydrogen-type UZM-8 molecular sieve and disperse it in 100 g of hydrochloric acid. After stirring for 2 h, add 0.5 g of mercaptoethanol dropwise. After continuing to stir for 20 min, add 1.5 g of hydrogen peroxide (30 wt%) dropwise. Then continue to stir at room temperature (20-25° C.) for 24 h.

[0074] (2) The stirred solution was placed in a crystallization reactor and reacted at 100°C for 12 hours.

[0075] (3) The crystallized liquid was washed with deionized water and ethanol several times until the upper clear liquid was neutral, and then dried at 80°C for 20 hours to obtain modified UZM-8. The material was measured by BET, and the value of external specific surface area / total specific surface area was 0.35. The S content was obtained by ICP measurement, and the SiO 2 / SO 3 The H molar ratio is 50.7. Pyridine infrared measurement The ratio of / Lewis is 2.2.

[0076] Embodiment 3-4

[0077] With fructose as substrate, tetrahydrofuran (THF) and deionized water as solvent, 0.2g of the modified SCM-1 in Example 1 and 0.2g of the modified UZM-8 in Example 2 were added into a stirred autoclave with 0.4g of fructose, 18g of THF and 2g of deionized water. 1.0MPa of nitrogen was filled to prevent the organic solvent from boiling. The temperature was raised to a preset temperature of 150°C using a programmed heating jacket (at 20°C / min), and then stirred using magnetic stirring. The reaction was carried out at 150°C for 30min, and the reaction solution was analyzed to obtain the fructose conversion rate and the yield of the target product 5-hydroxymethylfurfural (HMF), as shown in Table 1. Figure 5 This is the effect curve of the reaction time of H-SCM-1-SO3H at 150°C on the conversion of fructose to HMF in Example 1.

[0078] Table 1

[0079] Fructose conversion rate (%) HMF yield (%) Example 3 (Modified SCM-1) 99.9 87.1 Example 4 (Modified UZM-8) 99.9 82.5

[0080] Example 5

[0081] The same as Example 3, except that 18 g of THF and 1 g of deionized water were added to the autoclave. The reaction solution was analyzed to obtain the fructose conversion rate and the yield of the target product 5-hydroxymethylfurfural (HMF), as shown in Table 2.

[0082] Example 6

[0083] The same as Example 3, except that 18 g of THF and 4.5 g of deionized water were added to the autoclave. The reaction solution was analyzed to obtain the fructose conversion rate and the yield of the target product 5-hydroxymethylfurfural (HMF), as shown in Table 2.

[0084] Example 7

[0085] The same as Example 3, except that the reaction was carried out at 80° C. for 30 min, and the reaction solution was analyzed to obtain the fructose conversion rate and the yield of the target product 5-hydroxymethylfurfural (HMF), as shown in Table 2.

[0086] Example 8

[0087] The same as Example 3, except that the reaction was carried out at 220° C. for 30 min, and the reaction solution was analyzed to obtain the fructose conversion rate and the yield of the target product 5-hydroxymethylfurfural (HMF), as shown in Table 2.

[0088] Example 9

[0089] The same as Example 3, except that the reaction was carried out at 150° C. for 15 min, and the reaction solution was analyzed to obtain the fructose conversion rate and the yield of the target product 5-hydroxymethylfurfural (HMF), as shown in Table 2.

[0090] Example 10

[0091] The same as Example 3, except that the reaction was carried out at 150° C. for 240 min. The reaction solution was analyzed to obtain the fructose conversion rate and the yield of the target product 5-hydroxymethylfurfural (HMF), as shown in Table 2.

[0092] In order to more intuitively describe the reaction conditions and results of the above examples, the results of various parameters are listed in Table 2.

[0093] Table 2

[0094]

[0095] Embodiment 11

[0096] The same as Example 3, except that fructose was replaced by an equal amount of glucose. The reaction solution was analyzed to find that the glucose conversion rate was 98.5%, and the yield of the target product 5-hydroxymethylfurfural (HMF) was 75.2%.

[0097] Example 12

[0098] The molecular sieve preparation steps were the same as in Example 1, except that 3-mercaptopropyltrimethoxysilane was not added and hydrogen peroxide (30 wt%) was added. The reaction method was the same as in Example 3, and the reaction solution was analyzed to obtain a fructose conversion rate of 99.3% and a target product 5-hydroxymethylfurfural (HMF) yield of 63.7%.

[0099] Embodiment 13

[0100] Same as Example 12, except that the molecular sieve type is UZM-8 molecular sieve. Analysis of the reaction solution revealed that the fructose conversion rate was 95.3%, and the yield of the target product 5-hydroxymethylfurfural (HMF) was 60.7%.

[0101] Embodiment 14

[0102] The MCM-22 molecular sieve raw powder synthesized according to the preparation method described in the literature [Chinese Journal of Catalysis 41(2020)1062-1066] was calcined to remove the structure directing agent, and then ion exchange and calcination were performed to obtain hydrogen-type MCM-22 with a silicon-aluminum ratio (molecular ratio) of 30.

[0103] The steps for preparing modified MCM-22 molecular sieve from hydrogen-type MCM-22 are as follows:

[0104] (1) Prepare 2.0 M HCl, weigh 1 g of the hydrogen-type MCM-22 molecular sieve and disperse it in 100 g of hydrochloric acid. After stirring for 5 h, add 1.0 g of 3-mercaptopropyltrimethoxysilane dropwise. After continuing to stir for 20 min, add 1.8 g of hydrogen peroxide (30 wt%) dropwise, and then continue to stir at room temperature for 24 h.

[0105] (2) The stirred solution was placed in a crystallization reactor and reacted at 100°C for 10 hours.

[0106] (3) The crystallized liquid was washed several times with deionized water and ethanol until the upper clear liquid was neutral, and then dried at 80°C for 20 hours. The value of the external specific surface area / total specific surface area of ​​the material was 0.16 by BET measurement. The S content was calculated by ICP measurement, SiO 2 / SO 3 The H molar ratio is 205.

[0107] / Lewis ratio is 1.2

[0108] The reaction method was the same as in Example 3. Analysis of the reaction solution revealed that the fructose conversion rate was 99.5% and the yield of the target product 5-hydroxymethylfurfural (HMF) was 53.2%.

[0109] Comparative Example 1

[0110] The steps for preparing modified ZSM-5 molecular sieve from hydrogen ZSM-5 molecular sieve are as follows:

[0111] (1) Prepare a 2.0 M HCl solution, weigh 1 g of hydrogen-type ZSM-5 molecular sieve and disperse it in 100 g of hydrochloric acid. After stirring for 5 h, add 1.0 g of 3-mercaptopropyltrimethoxysilane dropwise. After continuing to stir for 20 min, add 1.8 g of hydrogen peroxide (30 wt%) dropwise, and then continue stirring at room temperature (20° C.) for 24 h.

[0112] (2) The stirred solution was placed in a crystallization reactor and reacted at 100°C for 10 hours.

[0113] (3) The crystallized liquid was washed with deionized water and ethanol several times until the supernatant was neutral, and then dried at 80 °C for 20 h to obtain modified ZSM-5, SiO 2 / SO 3 The H molar ratio is 273, The ratio of θ / Lewis is 1.0.

[0114] The reaction method was the same as in Example 3. Analysis of the reaction solution revealed that the fructose conversion rate was 85.5% and the yield of the target product 5-hydroxymethylfurfural (HMF) was 43.3%.

[0115] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for dehydrating biomass, characterized in that: The method comprises: contacting and reacting biomass with MWW molecular sieve in the presence of a solvent and an inert atmosphere.

2. The method according to claim 1, wherein: The biomass is selected from at least one of fructose, glucose, sucrose and maltose, preferably at least one of fructose and glucose.

3. The method according to claim 1 or 2, wherein: The conditions of the contact reaction include: Heating the reaction mixture to a temperature of 80-220°C, preferably 100-180°C, at a heating rate of 5°C / min-40°C / min, preferably 10°C / min-30°C / min; and / or The reaction time is 10 min-20 h, preferably 20 min-200 min; and / or The mass ratio of biomass to MWW molecular sieve is 1-50:1, preferably 1-20:

1.

4. The method according to any one of claims 1 to 3, wherein: The solvent includes water and an organic solvent. Preferably, The organic solvent is selected from at least one of toluene, cyclohexane, dichloromethane, tetrahydrofuran, acetone and methyl isobutyl ketone; and / or The volume ratio of the organic solvent to water is 4-20:1, preferably 6-10:1; and / or The mass ratio of water to biomass is 1:0.01-2, preferably 1:0.2-1.

2.

5. The method according to any one of claims 1 to 4, wherein: The method comprises: adding an organic solvent and a catalyst to a biomass aqueous solution, introducing an inert gas, heating the solution to a reaction temperature, cooling the solution after the reaction, and obtaining a biomass dehydration product; preferably, The temperature is lowered to 10-25°C at a rate of 5°C / min-40°C / min, preferably at a rate of 10°C / min-30°C / min.

6. The method according to any one of claims 1 to 5, wherein: The inert atmosphere is at least one of a nitrogen atmosphere, an argon atmosphere and a helium atmosphere.

7. The method according to any one of claims 1 to 6, wherein: The MWW molecular sieve The ratio is 1.5-5.0, preferably 1.9-4.0; and / or The external specific surface area / total specific surface area of ​​the MWW molecular sieve is 0.2-0.9, preferably 0.3-0.

7.

8. The method according to any one of claims 1 to 7, wherein: The MWW molecular sieve is a sulfonate-modified MWW molecular sieve.

9. The method according to claim 8, wherein: The sulfonate-modified MWW molecular sieve has a schematic chemical composition as shown in the formula "mSiO2·nAl2O3·pSO3H", wherein 20≤m / n≤66, 25≤m / p≤150.

10. The method according to any one of claims 1 to 9, wherein: The MWW molecular sieve is at least one selected from SCM-1 molecular sieve, UZM-8 molecular sieve, and MCM-56 molecular sieve, preferably SCM-1 molecular sieve.

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