Method for preparing 2, 5-dimethylfuran through biomass conversion

Abstract

The invention discloses a method for preparing 2, 5-dimethylfuran through biomass conversion. The method comprises the following steps: (1) in the presence of a plurality of organic solvents, carrying out contact reaction on a biomass raw material and a solid acid catalyst to obtain an organic solution containing 5-hydroxymethylfurfural and a 5-hydroxymethylfurfural functional group partial passivation product; (2) the organic solution obtained in the step (1), hydrogen and a hydrogenolysis catalyst are subjected to a contact reaction, and 2, 5-dimethylfuran is prepared. The method has the advantages of high product selectivity, good catalyst stability and easy product separation, and realizes green and efficient conversion from biomass to 2, 5-dimethylfuran.

Description

Technical Field

[0001] The invention belongs to the field of catalytic chemistry, and in particular relates to a method for preparing 2,5-dimethylfuran by biomass conversion. Background Art

[0002] With the advancement of science and technology and the development of society, the demand for traditional fossil energy such as coal, oil and natural gas is increasing, which leads to the depletion of fossil energy reserves on the earth, and the combustion of fossil energy will seriously pollute the environment. On the contrary, biomass, as a green renewable energy, has abundant reserves on the earth, and the conversion and utilization process will not pollute the environment, so many scholars have set their sights on using biomass to supplement fossil energy. 2,5-Dimethylfuran (DMF), as an important product of biomass chemical conversion, has good application prospects and can be used as a fuel with high energy density (31.5MJ / L) and octane number (119). Compared with traditional biomass ethanol, DMF has obvious advantages and is more suitable as a gasoline additive. At the same time, due to the diene bond on its furan ring, it can also react with monoolefins such as ethylene to undergo Diels-Alder reaction (DA reaction) to directly synthesize bio-based p-xylene.

[0003] 2,5-dimethylfuran is mainly prepared by hydrogenolysis of 5-hydroxymethylfurfural (HMF). When hydrogen is used as a hydrogen source, commonly used catalysts include loaded noble metals such as ruthenium (Ru), platinum (Pt) and palladium (Pd), as well as transition metals such as nickel (Ni), copper (Cu), cobalt (Co), etc. CN105032427A reported that Ru / Co3O4 prepared by coprecipitation had a conversion rate of HMF exceeding 99% under 130°C and 0.7MPa H2 conditions, achieving a DMF yield of 93.4%. Among them, 2,5-dimethylfuran is mainly prepared by hydrogenolysis of 5-hydroxymethylfurfural under the catalytic action of noble metals or non-noble metals, but the current production process often has problems such as high raw material cost and short catalyst life, resulting in high DMF prices and difficulty in large-scale application. CN103554066A reported a strategy for preparing 2,5-dimethylfuran from fructose using nickel-tungsten carbide as a catalyst with activated carbon as a carrier. First, a tetrahydrofuran system containing sulfuric acid is used to carry out a dehydration reaction at 160°C to prepare 5-hydroxymethylfurfural (the highest yield is 64%), and then under the action of a nickel-tungsten carbide catalyst with activated carbon as a carrier, a maximum of 95% DMF is prepared. CN103554066A reports a method for producing 2,5-dimethylfuran from fructose in one step, using fructose as a raw material, Ru / C and AlCl3 and inorganic acid as catalysts, and N, N'-dimethylformamide as a solvent, and the DMF yield can reach up to 66.3%. The above reaction process involves the use of liquid acid. Although the catalytic effect is excellent, liquid acid has problems such as serious equipment corrosion, large environmental pollution caused by alkali neutralization treatment of waste liquid, and many side reactions. At the same time, there are a large number of by-products (such as humin, etc.), which affect the separation of products and the stability of hydrogenolysis catalysts. And the reaction substrate concentrations of HMF hydrogenolysis to generate DMF reported so far are all low, and obtaining pure DMF will greatly increase the separation cost. Therefore, there is a great need for an efficient and green method for catalyzing the preparation of 2,5-dimethylfuran from biomass, which can efficiently convert biomass raw materials such as fructose and glucose into 2,5-dimethylfuran. Summary of the invention

[0004] The technical problem to be solved by the present invention is the low catalytic efficiency, high cost, environmental pollution and other problems in the prior art of 2,5-dimethylfuran preparation process, and a method for preparing 2,5-dimethylfuran by biomass conversion is provided. The method is simple to operate, has the advantages of high product selectivity, good catalyst stability and easy product separation, and realizes the green and efficient conversion of biomass to 2,5-dimethylfuran.

[0005] In order to solve the above technical problems, the present invention provides a method for preparing 2,5-dimethylfuran by biomass conversion, comprising:

[0006] (1) in the presence of a plurality of organic solvents, the biomass raw material is contacted with a solid acid catalyst to react, thereby obtaining an organic solution containing 5-hydroxymethylfurfural and a partially passivated product of 5-hydroxymethylfurfural functional groups;

[0007] (2) The organic solution obtained in step (1) and hydrogen are contacted with a hydrogenolysis catalyst to react to obtain 2,5-dimethylfuran.

[0008] According to the present invention, the biomass raw material in step (1) is one or more of cellulose, inulin, cellobiose, sucrose, glucose or fructose, preferably fructose and / or glucose, and more preferably fructose.

[0009] According to the present invention, in step (1), the organic solvent comprises solvent I and solvent II, wherein solvent I is an alcohol solvent, preferably at least one of methanol, ethanol, n-propanol, n-butanol, isopropanol, isopentanol, ethylene glycol, propylene glycol, glycerol or octanol, and further preferably one or two of isopropanol, isopentanol or n-butanol; solvent II is selected from at least one of acetone, tetrahydrofuran, 1,4-dioxane, methyl isobutyl ketone, γ-valerolactone or toluene, and preferably one or two of acetone, 1,4-dioxane or tetrahydrofuran.

[0010] According to the present invention, the mass ratio of solvent I to solvent II is 0.1-100:1, preferably 0.5-20:1; the mass ratio of the total mass of the organic solvent to the biomass raw material is 1-100:1, preferably 2-50:1; the mass ratio of the biomass raw material to the solid acid catalyst is 0.2-20:1, preferably 0.4-20:1.

[0011] According to the present invention, the reaction temperature in step (1) is 90 to 220° C., preferably 120 to 200° C., and the reaction time is 5 to 300 minutes, preferably 10 to 240 minutes. Further, the reaction is carried out under an inert gas (such as nitrogen) with an inert gas pressure of 0.1 to 3.0 MPa, preferably 0.5 to 2.0 MPa.

[0012] According to the present invention, the solid acid catalyst in step (1) is selected from any one of SCM-36-SO3H molecular sieve, SCM-1-SO3H molecular sieve, H-beta molecular sieve, USY molecular sieve, sulfonated carbon or A-15 resin; preferably, the solid acid catalyst is SCM-36-SO3H molecular sieve; preferably, the SCM-36-SO3H molecular sieve The acid / Lewis acid ratio is 2.2 to 4.0; in the SCM-36-SO3H molecular sieve, the content of -SO3H is 1.9wt% to 18.0wt%; the ratio of the surface specific area to the total specific surface area of ​​the SCM-36-SO3H molecular sieve is 0.25 to 1.0, preferably 0.3 to 0.7.

[0013] According to the present invention, the preparation method of the SCM-36-SO3H molecular sieve comprises the following steps:

[0014] S1. Disperse H-SCM-36 molecular sieve in toluene, add thiol compound to form reaction solution A, and stir thoroughly;

[0015] S2, filtering the reaction solution A, and washing it with dichloromethane and ethyl acetate under reflux to obtain a solid B;

[0016] S3, mix solid B, hydrogen peroxide, alcohol and water evenly, and stir at room temperature for 8 to 30 hours;

[0017] S4. After filtering the suspension obtained in S3, add dilute sulfuric acid, stir, filter, wash and dry to obtain SCM-36-SO3H molecular sieve.

[0018] According to the present invention, the SCM-36 molecular sieve raw powder is calcined to remove the structure directing agent, and then ion exchange and calcination are performed to obtain the H-SCM-36 molecular sieve. Among them, calcination and ion exchange are both conventional operations in the art. Preferably, the silicon-aluminum ratio of the H-SCM-36 molecular sieve is 20 to 50; the ratio of the terminal silanol group to the sum of the internal silanol group and the bridging hydroxyl group is 0.4 to 1.2.

[0019] According to the present invention, SCM-36 molecular sieve is prepared by the following method:

[0020] A silicon source, sodium aluminate, sodium hydroxide, an organic structure directing agent and water are prepared into a crystallization solution, separated and dried after crystallization treatment to obtain SCM-36 molecular sieve raw powder. Further, the silicon source is at least one of silica sol and silica gel; the content of Al2O3 in the sodium aluminate is 38% to 43% by weight, and the content of Na2O is 30% to 33% by weight; the organic structure directing agent contains a trimethylethylammonium ion structure; in the crystallization solution, the molar ratio of the silicon source in terms of SiO2, the sodium aluminate in terms of Al2O3, the sodium hydroxide, the organic structure directing agent in terms of trimethylethylammonium ions and water is 1: 0.016 to 0.050: 0.10 to 0.20: 0.15 to 0.30: 10 to 50. Further, the crystallization treatment conditions are: the crystallization temperature is 155 to 175°C, and the crystallization time is 2 to 8 days. Further, separation and drying are both conventional operations in this field.

[0021] According to the present invention, in step S1, the thiol compound is selected from one or more of mercaptoethanol, thioglycolic acid, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, dimethylmercaptopropionic acid, methyl mercaptopropionate, 1,3-dimercaptopropane or 2,3-dimercapto-1-propanol; preferably 3-mercaptopropyltrimethoxysilane or 3-mercaptopropyltriethoxysilane.

[0022] According to the present invention, in step S1, the mass ratio of toluene to molecular sieve is 10 to 200:1, preferably 20 to 100:1; the molar ratio of thiol compound to H-SCM-36 molecular sieve is 0.0001 to 0.5, preferably 0.0005 to 0.5. The stirring conditions are: temperature of 25 to 30° C., and time of 5 to 48 hours.

[0023] According to the present invention, in step S2, the mass ratio of dichloromethane to H-SCM-36 molecular sieve is 10 to 80:1; the mass ratio of ethyl acetate to H-SCM-36 molecular sieve is 10 to 80:1; and the reflux washing time is 6 to 30 hours.

[0024] According to the present invention, in step S3, the molar ratio of hydrogen peroxide to H-SCM-36 molecular sieve is 1-100, preferably 2-60.

[0025] According to the present invention, in step S3, the alcohol is one or more of methanol or ethanol. The mass ratio of the alcohol to the H-SCM-36 molecular sieve is 100 to 300:1.

[0026] According to the present invention, in step S3, the mass ratio of water to molecular sieve is 200-600:1.

[0027] According to the present invention, in step S4, the concentration of dilute sulfuric acid is 0.1-1.0 mol / L, and the amount of dilute sulfuric acid added is 10-100 mL / 1 g molecular sieve.

[0028] According to the present invention, in step S4, the stirring conditions are: temperature of 25 to 30° C., and time of 5 to 48 hours.

[0029] According to the present invention, in step (2), the mass ratio of the organic solution containing 5-hydroxymethylfurfural and its passivation product obtained in step (1) to the hydrogenolysis catalyst is 30 to 200:1, preferably 50 to 150.

[0030] According to the present invention, hydrogen is charged into the reaction system in step (2) to adjust the reaction pressure, which is 0.5 to 4.0 MPa, preferably 0.5 to 3.0 MPa.

[0031] According to the present invention, the reaction conditions of step (2) are as follows: the reaction temperature is 130 to 220° C., preferably 150 to 200° C.; the reaction time is 1 to 12 hours, preferably 2 to 10 hours.

[0032] According to the present invention, the product obtained in step (2) can be separated to obtain 2,5-dimethylfuran by conventional methods, such as distillation separation.

[0033] According to the present invention, the hydrogenolysis catalyst in step (2) is a precious metal and / or non-precious metal hydrogenation catalyst, including any one of Pd / C, Pt / C, Ru / C, Pd / Al2O3, Pt / Al2O3, Ru / Al2O3, Ru / Co3O4, Ni-Co3O4 / C, Ni-Al2O3, Ni-Fe / C or Ni-SCM-X; preferably Ni-SCM-X.

[0034] According to the present invention, X in the Ni-SCM-X is 14 or 15. SCM-14 molecular sieve and its preparation method are described in patent CN109081360A, and the entire contents of the patent are fully incorporated into the present invention as a reference. SCM-15 molecular sieve and its preparation method are described in patent CN109081359A, and the entire contents of the patent are fully incorporated into the present invention as a reference.

[0035] According to the present invention, the Ni-SCM-X has a Ni content of 0.2wt% to 5.0wt%, preferably 0.5wt% to 3.0wt%, based on the mass of SCM-X; the Si / Ge molar ratio of the SCM-X is 1.5 to 8, preferably 2 to 7.

[0036] According to the present invention, the total acid content of the Ni-SCM-X is 130 to 220 μmol·g -1 , preferably 150 to 200 μmol·g -1 .

[0037] According to the present invention, the Ni-SCM-X The acid / Lewis acid ratio is 0.3 to 0.8, preferably 0.4 to 0.6.

[0038] According to the present invention, in the Ni-SCM-X, metallic Ni and Ni 2+ The molar ratio (Ni / Ni 2+ ) is 0.02 to 0.15, preferably 0.05 to 0.12.

[0039] According to the present invention, in the Ni-SCM-X, the average size of nickel particles is 2 to 6 nm, preferably 3 to 5 nm.

[0040] According to the present invention, the preparation method of Ni-SCM-X comprises:

[0041] The SCM-X molecular sieve is mixed with a nickel-containing precursor, and the obtained product is dried, calcined and reduced to obtain Ni-SCM-X. In the SCM-X molecular sieve, X is 14 or 15.

[0042] According to the present invention, the nickel-containing precursor is selected from at least one of nickelocene (bis(cyclopentadiene)nickel), bis-(1,5-cyclooctadiene)nickel, bis(tetramethylcyclopentadienyl)nickel, 1,2-bis(diphenylphosphine)ethane nickel chloride and bis(triphenylphosphine)nickel chloride, preferably nickelocene.

[0043] According to the present invention, the mass ratio of Ni (theoretical amount of Ni in the organometallic precursor) to SCM-X molecular sieve is 0.2-8.0:100, preferably 0.5-5.0:100.

[0044] According to the present invention, the mixing is physical mixing, and the mixing methods include grinding, ball milling and the like.

[0045] According to the present invention, the drying conditions are: drying at 50-130° C. for 2-8 hours.

[0046] According to the present invention, the calcination conditions are: calcination at 300-650° C. for 1-12 hours, and the calcination atmosphere is oxygen or air.

[0047] According to the present invention, the reduction is preferably carried out under a hydrogen atmosphere, the reduction temperature is 300 to 500° C., preferably 350 to 450° C., and the reduction time is 1 to 8 hours, preferably 2 to 6 hours.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) The present invention uses biomass as raw material, which is cheap and widely available. By adopting a functional group protection strategy, the intermediate product HMF, which is chemically active, unstable and difficult to store, is selectively passivated in a one-step method to generate RMF, which reduces the self-polymerization of HMF and the formation of other by-products to a certain extent, and achieves a high yield of the target product while increasing the substrate concentration.

[0050] (2) The present invention directly uses RMF for hydrogenolysis reaction, breaks the carbon-oxygen bond while eliminating the protecting group, completes the hydrogenation reaction, and generates DMF. This solves the problem of generally low carbon yield in the reaction of generating DMF by hydrogenolysis of high-concentration HMF, and also avoids the high separation energy consumption caused by too low concentration.

[0051] (3) The present invention finally obtains the product DMF by connecting the whole process of biomass-RMF (HMF) and RMF (HMF)-DMF in series. The two-step reaction adopts the same dual organic solvent system, and no complicated RMF or HMF separation process is involved in the middle. The protection and elimination of active groups are achieved in the process of connecting the two-step reaction in series, and no other by-products are generated in the whole process.

[0052] (4) The present invention uses a new structure SCM series molecular sieve as a catalyst. In the sugar-RMF (HMF) reaction, H-SCM-36 with a large number of surface silanol groups is preferably used for sulfonate loading; in the RMF (HMF)-DMF reaction, silicon germanium molecular sieves SCM-14 or SCM-15 are preferably used for metal loading and selective hydrogenation. The catalytic materials used in the whole process add color to the creation of a bio-based PX production line. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The schematic diagram of the process of preparing 2,5-dimethylfuran by biomass conversion of the present invention;

[0054] Figure 2 The infrared images of SCM-36 and conventional FER molecular sieves;

[0055] Figure 3 The XRD pattern of the solid acid catalyst (SCM-36-SO3H) obtained in Example 1;

[0056] Figure 4 This is a SEM image of the solid acid catalyst (SCM-36-SO3H) obtained in Example 1;

[0057] Figure 5 This is the pyridine infrared image of the solid acid catalyst (SCM-36-SO3H) obtained in Example 1;

[0058] Figure 6 is the XRD pattern of the hydrogenolysis catalyst (Ni-SCM-14) obtained in Example 21;

[0059] Figure 7 NH3-TPD diagram of the hydrogenolysis catalyst (Ni-SCM-14) obtained in Example 21;

[0060] Figure 8 This is the XPS graph of the hydrogenolysis catalyst (Ni-SCM-14) obtained in Example 21;

[0061] Fig. 9 TEM image of the hydrogenolysis catalyst (Ni-SCM-14) obtained in Example 21;

[0062] Fig.10This is the XRD pattern of the hydrogenolysis catalyst (Ni-SCM-15) obtained in Example 22. DETAILED DESCRIPTION

[0063] In the present invention, the NH3 temperature-programmed desorption (NH3-TPD) experiment is carried out on a TPD / TPR Altamira AMI-3300 instrument, and the total acid content is calculated by fitting and peak separation of the obtained spectrum.

[0064] In the present invention, the product XRD measurement method is: using Japan Rigaku Ultima IV X-ray powder diffractometer to analyze the physical phase of the sample, CuKα ray source Nickel filter, 2θ scanning range 2°-50°, operating voltage 35 kV, current 25 mA, scanning rate 10° / min.

[0065] In the present invention, the pyridine adsorption infrared method (Nicolet Model 710 spectrometer) is used to determine the acid content and acid type of the catalyst. The specific operating steps are as follows: a. Sample pretreatment. The sample (about 30 mg) is pressed into a thin disc with a diameter of 13 mm and loaded into an infrared sample tank; thereafter, the sample is pretreated under vacuum cell conditions and at 400°C for 1 hour. After the sample tank is cooled to room temperature, the sample infrared data is scanned as the background. b. Pyridine adsorption. At room temperature and vacuum environment, pyridine vapor is introduced into the original position until the adsorption reaches equilibrium, and the adsorption time is 1 hour. c. Pyridine desorption. After the adsorption is completed, vacuum is evacuated at 100°C until the internal pressure no longer changes. The desorption time is 40 minutes, and the infrared absorption spectrum is scanned and recorded respectively. The difference spectrum before and after pyridine adsorption is the obtained pyridine adsorption-infrared absorption spectrum. The acid content of the sample is semi-quantitatively calculated based on the spectrum:

[0066]

[0067] Where r and w are the diameter (cm) and mass (g) of the catalyst disc, A is the integral value of the absorbance at the specified wave number peak based on the scanning pyridine adsorption-infrared absorption spectrum. IMEC is the integrated molar extinction coefficient, IMEC L 2.22, IMEC B is 1.67, C L is the amount of L acid (μmol·g -1 ), C B is the acid content of B (μmol·g -1 ).

[0068] In the present invention, the transmission electron microscope (TEM) model of the molecular sieve is S-4800I1 field emission scanning electron microscope. The size of the nickel particles in the molecular sieve is obtained by selecting the size of about 30 nickel particles for statistics through the TEM image and then calculating the average value.

[0069] In the present invention, the determination of the binding energy of the elements on the catalyst surface is carried out on an X-ray photoelectron spectrometer (ESCA LAB-250) produced by Thermo Company, and C1s=284.6 eV is used as the internal standard to calibrate the measured element signal.

[0070] In the present invention, the inductively coupled plasma atomic emission spectrometer (ICP) model is Varian 725-ES, and the analysis sample is dissolved with hydrofluoric acid to detect the content of the metal element.

[0071] In the present invention, 5-hydroxymethylfurfural (HMF), 5-R-oxymethylfurfural (R=ethyl, propyl, butyl, etc., referred to as RMF), and 2,5-dimethylfuran (DMF) are qualitatively analyzed by gas chromatography-mass spectrometry (GC-MS), and the yield and conversion rate of 5-hydroxymethylfurfural and 5-R-oxymethylfurfural, as well as the yield of the reaction product 2,5-dimethylfuran are analyzed by gas chromatography (GC). The gas chromatography-mass spectrometer 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 hydrogen flame ionization detector (FID), and the chromatographic column is SE-54 capillary column (30m, 0.53mm).

[0072] The reaction of preparing DMF from biomass raw materials is divided into two processes. The first process is to prepare HMF and RMF from biomass raw materials. The calculation formula of HMF and RMF yield is:

[0073] The yield of the product HMF and RMF (%) = (molar amount of HMF and RMF generated by the reaction n1) / (molar amount of hexose units in the reaction substrate biomass n0) × 100%. Among them, the hexose unit is C6H 10 O5.

[0074] In the second process, HMF and RMF (n1) generated in the first process are used as raw materials to react with hydrogen to prepare DMF. The conversion formula of HMF and RMF is:

[0075] The conversion rate of HMF and RMF (%) = (the molar amount of HMF and RMF remaining after the second process reaction is completed n2) / (the molar amount of HMF and RMF in the second process reactants n1) × 100%.

[0076] In the second process, the product DMF selectivity formula is:

[0077] The selectivity of the product DMF (%) = (the molar amount of DMF generated by the reaction n3) / (the molar amount of HMF and RMF in the second process reactants n1 - the molar amount of HMF and RMF remaining after the second process reaction is completed n2) × 100%.

[0078] Combination Figure 1 The process of preparing 2,5-dimethylfuran by biomass conversion of the present invention is described as follows:

[0079] (1) in the presence of a plurality of organic solvents, the biomass raw material is contacted with a solid acid catalyst to react, thereby obtaining an organic solution containing 5-hydroxymethylfurfural and a partially passivated product of 5-hydroxymethylfurfural functional groups;

[0080] (2) The organic solution containing 5-hydroxymethylfurfural and partially passivated products of 5-hydroxymethylfurfural functional groups obtained in process (1) is contacted with hydrogen and a hydrogenolysis catalyst to obtain a reaction product containing 2,5-dimethylfuran. The reaction product containing 2,5-dimethylfuran can be subjected to a subsequent separation process to obtain 2,5-dimethylfuran.

[0081] In order to facilitate the understanding of the present invention, the present invention lists the following embodiments, but the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0082] Example 1

[0083] 14.35 g of deionized water, 0.604 g of sodium aluminate (containing 40.5% by weight of Al2O3, 30.6% by weight of Na2O, and the balance being H2O), 0.366 g of sodium hydroxide, 7.06 g of trimethylethylammonium hydroxide solution (containing 25.00% by weight of trimethylethylammonium hydroxide) (organic structure directing agent R) and 12.60 g of silica sol (containing 40.0% by weight of SiO2) were stirred at room temperature for 4 hours to obtain a mixture. The final material ratio (molar ratio) was:

[0084] SiO2 / Al2O3=35;

[0085] NaOH / SiO2=0.18;

[0086] Trimethylethylammonium hydroxide (R) / SiO2 = 0.20;

[0087] H2O / SiO2=18.

[0088] The mixture was placed in a stainless steel reactor and heated for crystallization at 170°C and 20 rpm for 3 days. After crystallization, the product was filtered, washed, and dried in an oven at 100°C overnight. The XRD spectrum of the obtained product is shown in the figure below. Figure 1 As shown in Table 1, it is SCM-36 molecular sieve.

[0089] The SCM-36 molecular sieve obtained above is calcined to remove the structure directing agent, and then ion exchange and calcination are performed to obtain H-SCM-36. The infrared image of H-SCM-36 is shown in Figure 2 As shown, 3739cm -1 It can be seen from the figure that the Si-OH of H-SCM-36 molecular sieve is more than that of conventional FER molecular sieve.

[0090] Add 1.5g H-SCM-36 molecular sieve and 1.0g 3-mercaptopropyltrimethoxysilane to 50g toluene and stir for 24h at 25-30℃. After stirring, filter and add 30.0g dichloromethane and 30.0g ethyl acetate to reflux and wash for 24h. Then add the solid obtained above to a mixture of 40g H2O2 (30%), 120g methanol and 400g deionized water and stir for 15h at room temperature. After stirring, filter and add the precipitate to 40mL sulfuric acid (0.6mol / L) to disperse and stir for 15h. Finally, wash and dry with ethanol and water to obtain H-SCM-36-SO3H.

[0091] The XRD characteristics of the samples are as follows Figure 3 The SEM of the sample is shown in Figure 4 The pyridine infrared image of the sample is shown in Figure 5 As shown, the calculated The acid ratio is 3.3.

[0092] Example 2

[0093] The H-SCM-36 molecular sieve is the same as in Example 1.

[0094] Add 1.5g H-SCM-36 and 0.5g 3-mercaptopropyltrimethoxysilane to 50g toluene and stir thoroughly at 25-30°C for 24h. After stirring, filter and add 30.0g dichloromethane and 30.0g ethyl acetate to reflux and wash for 24h. Then add the above-obtained solid to a mixture of 40g H2O2 (30%), 120g methanol and 400g deionized water and stir at room temperature for 15h. After stirring, filter and add the precipitate to 40mL sulfuric acid (0.6mol / L) to disperse and stir thoroughly for 15h. Finally, wash and dry thoroughly with ethanol and water to obtain H-SCM-36-SO3H.

[0095] XRD and Figure 3 Similar. SEM and Figure 4 Similar. Calculated from the pyridine infrared spectrum of the sample The acid ratio is 3.0.

[0096] Example 3

[0097] The H-SCM-36 molecular sieve is the same as in Example 1.

[0098] Add 1.5g H-SCM-36 and 1.0g 3-mercaptopropyltriethoxysilane to 50g toluene and stir thoroughly at 25-30°C for 24h. After stirring, filter and add 30.0g dichloromethane and 30.0g ethyl acetate to reflux and wash for 24h. Then add the above-obtained solid to a mixture of 40g H2O2 (30%), 120g methanol and 400g deionized water and stir at room temperature for 15h. After stirring, filter and add the precipitate to 40mL sulfuric acid (0.6mol / L) to disperse and stir thoroughly for 15h. Finally, wash and dry thoroughly with ethanol and water to obtain H-SCM-36-SO3H.

[0099] XRD and Figure 3 Similar. SEM and Figure 4 Similar. Calculated from the pyridine infrared spectrum of the sample The acid ratio is 3.1.

[0100] Example 4

[0101] The H-SCM-36 molecular sieve is the same as in Example 1.

[0102] Add 1.5g H-SCM-36 and 1.0g 3-mercaptopropyltrimethoxysilane to 50g toluene and stir thoroughly at 25-30°C for 24h. After stirring, filter and add 30.0g dichloromethane and 30.0g ethyl acetate to reflux and wash for 24h. Then add the above-obtained solid to a mixture of 20g H2O2 (30%), 120g methanol and 400g deionized water and stir at room temperature for 15h. After stirring, filter and add the precipitate to 40mL sulfuric acid (0.6mol / L) to disperse and stir thoroughly for 15h. Finally, wash and dry thoroughly with ethanol and water to obtain H-SCM-36-SO3H.

[0103] XRD and Figure 3 Similar. SEM and Figure 4 Similar. Calculated from the pyridine infrared spectrum of the sample The acid ratio is 2.9.

[0104] Table 1 Properties of solid acid catalysts of Examples 1-4

[0105]

[0106] Embodiment 5-8

[0107] With fructose as substrate, tetrahydrofuran and n-butanol as solvent, 0.5g of H-SCM-36-SO3H molecular sieve in the above-mentioned embodiment 1-4, 4.0g of fructose, 10g of tetrahydrofuran and 10g of n-butanol were added into a stirred autoclave. 0.5MPa of nitrogen was filled to prevent the organic solvent from boiling. The temperature was raised to a preset temperature by a programmed heating jacket, and then stirred by magnetic stirring. The reaction was carried out at 165°C for 30min, and the reaction liquid was analyzed to obtain the fructose conversion rate and the yields of the target products 5-hydroxymethylfurfural (HMF) and 5-R-oxymethylfurfural (RMF). The sum of the conversion rate and the yields of HMF and RMF is shown in Table 2.

[0108] Table 2 Catalyst evaluation results of Examples 1-4

[0109]

[0110] Example 9

[0111] With fructose as substrate, tetrahydrofuran and n-butanol as solvents, 0.5g USY, 4.0g fructose, 10g tetrahydrofuran and 10g n-butanol were added to a stirred autoclave, respectively. 0.5MPa nitrogen was introduced to prevent the organic solvent from boiling. The temperature was raised to the preset temperature by a programmed heating jacket, and then stirred by magnetic stirring. The reaction was carried out at 165°C for 30min, and the reaction liquid was analyzed to obtain the fructose conversion rate and the yields of the target products 5-hydroxymethylfurfural (HMF) and 5-R-oxymethylfurfural (RMF). The fructose conversion rate was greater than 99%, and the sum of the yields of HMF and RMF was 62.7%.

[0112] Example 10

[0113] With fructose as substrate, tetrahydrofuran and n-butanol as solvents, 0.5g A-15 resin, 4.0g fructose, 10g tetrahydrofuran and 10g n-butanol were added to a stirred autoclave. 0.5MPa nitrogen was added to prevent the organic solvent from boiling. The temperature was raised to the preset temperature by a programmed heating jacket, and then stirred by magnetic stirring. The reaction was carried out at 165°C for 30min, and the reaction liquid was analyzed to obtain the fructose conversion rate and the yields of the target products 5-hydroxymethylfurfural (HMF) and 5-R-oxymethylfurfural (RMF). The fructose conversion rate was greater than 99%, and the sum of the yields of HMF and RMF was 60.3%.

[0114] Examples 11-19

[0115] In order to more intuitively describe the reaction conditions and results of Examples 11-19, various parameters and reaction results are listed in Table 3, wherein the fructose conversion rates are all greater than 99%.

[0116] Table 3 Reaction conditions and results of Examples 11-19

[0117]

[0118] Embodiment 20

[0119] With fructose as substrate, tetrahydrofuran and n-butanol as solvent, 0.5g of the catalyst (H-SCM-36-SO3H) of Example 1, 4.0g of fructose, 10g of tetrahydrofuran and 10g of n-butanol were added to a stirred autoclave. 0.5MPa of nitrogen was filled to prevent the organic solvent from boiling. The heating jacket was heated to a preset temperature using a programmed temperature increase, and then stirred using a magnetic stirrer. The reaction was carried out at 165°C for 30min. The used catalyst was washed and dried and then put into the next reaction. The reaction was repeated 4 times in total. The catalytic evaluation results are shown in Table 4.

[0120] Table 4 Example 1 Catalyst Cycling Data

[0121] Cycle times Fructose conversion rate (%) HMF+RMF yield (%) 1 time ＞99 71.5 2 times ＞99 68.7 3 times ＞99 68.3 4 times ＞99 68.2

[0122] Embodiment 21

[0123] The SCM-14 molecular sieve was synthesized according to the preparation method in Example 1 described in CN109081360A, wherein the Si / Ge molar ratio was 3.7. The nickel precursor was nickelocene, and the mass ratio of Ni (theoretical amount of Ni in the organometallic precursor) to the above-mentioned SCM-14 molecular sieve was 1.1:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 100°C for 4 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions, the reduction temperature was 400°C, and the reduction time was 3 hours. Ni-SCM-14 molecular sieve was obtained.

[0124] The XRD characteristics of the samples are as follows Figure 6 The NH3-TPD of the sample is shown as Figure 7 As shown, the total acid content calculated is 176 μmol·g -1 The XPS of the sample is as follows Figure 8 As shown, the binding energy at 852.0 eV corresponds to the metal element Ni (2p 3 / 2 The peak with a binding energy of 855.6 eV corresponds to divalent nickel (2 + ), metallic Ni and Ni 2+ The molar ratio of Ni / Ni 2+ The TEM of the sample is as follows Fig. 9 As shown, it can be seen that the nickel is evenly distributed without obvious aggregation, and the average particle size of the nickel particles is 3.5nm. The relative content of Ni in the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) and was 1.1wt%. The sample was calculated by pyridine adsorption infrared test. The acid ratio is 0.52.

[0125] Embodiment 22

[0126] The SCM-15 molecular sieve was synthesized according to the preparation method in Example 1 described in CN109081359A, wherein the Si / Ge molar ratio was 5.1. The nickel precursor was nickelocene, and the mass ratio of Ni (theoretical amount of Ni in the organometallic precursor) to the above-mentioned SCM-15 molecular sieve was 1.2:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 80°C for 5 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions at a reduction temperature of 400°C and a reduction time of 2 hours. Ni-SCM-15 molecular sieve was obtained.

[0127] The XRD characteristics of the samples are as follows Fig.10 As shown. The NH3-TPD of the sample Figure 7 Similarly, the total acid content calculated from this is 155 μmol·g -1 The XPS and Figure 8 Similarly, the binding energy at 852.0 eV corresponds to the metal element Ni (2p 3 / 2 The peak with a binding energy of 855.6 eV corresponds to divalent nickel (2 + ), metallic Ni and Ni 2+ The molar ratio of Ni / Ni 2+ The ratio is 0.11. Fig. 9 Similarly, it can be seen that the nickel is evenly distributed without obvious aggregation, and the average particle size of the nickel particles is 4.0nm. The relative content of Ni in the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) and was 1.2wt%. The sample was calculated by pyridine adsorption infrared test. The acid ratio is 0.45.

[0128] Embodiment 23-24

[0129] 0.2 g of the catalyst in the above Examples 21-22 and 15 g of the reaction liquid obtained in Example 5 were added to a stirred autoclave, and 1.5 MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using a magnetic stirrer. The reaction was carried out at 190° C. for 3 h, and the HMF+RMF conversion rate and the product DMF selectivity were calculated by gas phase analysis of the reaction liquid, as shown in Table 5.

[0130] Table 5 Catalytic evaluation results of catalysts of Examples 21-22

[0131]

[0132] Embodiment 25

[0133] 0.2 g Ni-Fe / C hydrogenolysis catalyst and 15 g of the reaction liquid obtained in Example 5 were added to a stirred autoclave, and 1.5 MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using a magnetic stirrer. The reaction was carried out at 190° C. for 3 h, and the HMF+RMF conversion rate was calculated by gas phase analysis of the reaction liquid, and the product DMF selectivity was 71.2%.

[0134] Embodiment 26

[0135] 0.2 g of Pd / C hydrogenolysis catalyst and 15 g of the reaction liquid obtained in Example 5 were added to a stirred autoclave, and 1.5 MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using a magnetic stirrer. The reaction was carried out at 190° C. for 3 h, and the HMF+RMF conversion rate was calculated by gas phase analysis of the reaction liquid, and the product DMF selectivity was 70.1%.

[0136] Embodiment 27

[0137] 0.2 g of Ru / Al2O3 hydrogenolysis catalyst and 15 g of the reaction liquid obtained in Example 5 were added to a stirred autoclave, and 1.5 MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using a magnetic stirrer. The reaction was carried out at 190°C for 3 h, and the HMF+RMF conversion rate was calculated by gas phase analysis of the reaction liquid to be greater than 99%, and the product DMF selectivity was 73.5%.

[0138] Examples 28-33

[0139] The catalyst in Example 21 and the reaction product liquid obtained in Example 5 were added to a stirred high pressure reactor, and hydrogen was charged. The temperature was raised to a preset temperature using a programmed heating jacket, and magnetic stirring was used for reaction. In order to more intuitively describe the reaction conditions and results of Examples 28-33, various parameters and reaction results are listed in Table 6.

[0140] Table 6 Reaction conditions and results of Examples 28-33

[0141]

[0142] Embodiment 34

[0143] 0.2 g of the catalyst in Example 21 and 15 g of the reaction liquid obtained in Example 5 were added to a stirred autoclave, and 1.5 MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using a magnetic stirrer. The reaction was carried out at 190° C. for 3 h. The used catalyst was washed and dried and then put into the next reaction. The reaction was repeated 4 times in total. The catalytic evaluation results are shown in Table 7.

[0144] Table 7 Example 21 Catalyst Recycling Data

[0145] Cycle times HMF+RMF conversion rate (%) DMF selectivity (%) 1 time >99 80.5 2 times >99 78.9 3 times >99 78.2 4 times >99 77.8

[0146] Comparative Example 1

[0147] The alcohol solvents (tetrahydrofuran and n-butanol) in Example 5 were replaced with an equal amount of water.

[0148] With fructose as substrate and water as solvent, 0.5g of H-SCM-36-SO3H in Example 1, 4.0g of fructose and 20g of water were added to a stirred autoclave. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using a magnetic stirrer. The reaction was carried out at 165°C for 30 minutes, and the reaction liquid was analyzed to obtain the fructose conversion rate and the target product yield. The fructose conversion rate was >99%, and only 5-hydroxymethylfurfural (HMF) was generated, with an HMF yield of 25%.

[0149] 0.2g of the catalyst in Example 21 and 15g of the reaction liquid obtained in Comparative Example 1 were added to a stirred autoclave, and 1.5MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using a magnetic stirrer. The reaction was carried out at 190°C for 3h, and the selectivity of the product DMF was calculated by gas phase analysis of the reaction liquid. The HMF conversion rate was 99% and the DMF selectivity was 60%.

[0150] Comparative Example 2

[0151] The alcohol solvents (tetrahydrofuran and n-butanol) in Example 5 are replaced by a water-organic two-phase solvent system.

[0152] With fructose as substrate and water + n-butanol as solvent, 0.5g of H-SCM-36-SO3H in Example 1, 4.0g of fructose, 10g of water and 10g of n-butanol were added into a stirred autoclave. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using a magnetic stirrer. The reaction was carried out at 165°C for 30min, and the reaction liquid was analyzed to obtain the fructose conversion rate and the target product yield. The fructose conversion rate was >99%, and the sum of the yields of 5-hydroxymethylfurfural (HMF) and 5-R-oxymethylfurfural (RMF) was 48.1%.

[0153] 0.2 g of the catalyst in Example 21 and 15 g of the reaction liquid obtained in Comparative Example 2 were added to a stirred autoclave, and 1.5 MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using a magnetic stirrer. The reaction was carried out at 190° C. for 3 h, and the HMF+RMF conversion rate was calculated by gas phase analysis of the reaction liquid to be 80%, and the product DMF selectivity was 56%.

[0154] Comparative Example 3

[0155] The SCM-14 molecular sieve was synthesized according to the preparation method in Example 1 described in CN109081360A, wherein the Si / Ge molar ratio was 3.7. The nickel precursor was nickel levulinate, and the mass ratio of Ni (theoretical amount of Ni in nickel nitrate) to the above-mentioned SCM-14 molecular sieve was 1.0:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 100°C for 4 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions, the reduction temperature was 400°C, and the reduction time was 3 hours. Ni-SCM-14 molecular sieve was obtained.

[0156] The Si / Ge molar ratio of the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) to be 3.7, and the relative content of Ni was 1.0 wt %. The total acid content calculated by NH3-TPD of the sample was 161 μmol·g -1 Calculated based on the pyridine infrared image of the sample The acid ratio is 0.82. According to the XPS calculation of the sample (Ni / Ni 2+ The ratio is 0.35. According to the TEM results of the sample, the average particle size of the nickel particles is 10.3nm.

[0157] With fructose as substrate, tetrahydrofuran and n-butanol as solvent, 0.5g of H-SCM-36-SO3H in the above Example 1, 4.0g of fructose, 10g of tetrahydrofuran and 10g of n-butanol were added to a stirred autoclave. 0.5MPa of nitrogen was added to prevent the organic solvent from boiling. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using a magnetic stirrer. The reaction was carried out at 165°C for 30min, and the reaction liquid was analyzed to obtain the fructose conversion rate and the yields of the target products 5-hydroxymethylfurfural (HMF) and 5-R-oxymethylfurfural (RMF). The fructose conversion rate was >99%, and the HMF+RMF yield was 71.5%.

[0158] 0.2g of Ni-SCM-14 molecular sieve catalyst obtained in Comparative Example 3 and 15g of the reaction liquid obtained in Comparative Example 3 were added to a stirred autoclave, and 1.5MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using magnetic stirring. The reaction was carried out at 190°C for 3h, and the HMF+RMF conversion rate was calculated by gas phase analysis of the reaction liquid, and the product DMF selectivity was 75%, and 57%.

[0159] The above describes the specific implementation of the present invention in detail, 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 various technical features being combined 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 preparing 2,5-dimethylfuran by biomass conversion, comprising: (1) in the presence of a plurality of organic solvents, the biomass raw material is contacted with a solid acid catalyst to react, thereby obtaining an organic solution containing 5-hydroxymethylfurfural and a partially passivated product of 5-hydroxymethylfurfural functional groups; (2) The organic solution obtained in step (1) and hydrogen are contacted with a hydrogenolysis catalyst to react to produce 2,5-dimethylfuran.

2. The method according to claim 1, characterized in that: In step (1), the organic solvent comprises solvent I and solvent II; the solvent I is an alcohol solvent, preferably at least one of methanol, ethanol, n-propanol, n-butanol, isopropanol, isopentanol, ethylene glycol, propylene glycol, glycerol or octanol, and more preferably one or two of isopropanol, isopentanol or n-butanol; the solvent II is selected from at least one of acetone, tetrahydrofuran, 1,4-dioxane, methyl isobutyl ketone, γ-valerolactone or toluene, and preferably one or two of acetone, 1,4-dioxane or tetrahydrofuran; and / or, the mass ratio of solvent I to solvent II is 0.1 to 100:1, preferably 0.5 to 20:1; And / or, the mass ratio of the total mass of the organic solvent to the mass of the biomass raw material is 1 to 100:1, preferably 2 to 50:

1.

3. The method according to claim 1, characterized in that: In step (1), the biomass raw material is one or more of cellulose, inulin, cellobiose, sucrose, glucose or fructose, preferably fructose and / or glucose; And / or, in step (1), the mass ratio of the biomass raw material to the solid acid catalyst is 0.2 to 20:1, preferably 0.4 to 20:

1.

4. The method according to claim 1, characterized in that: In step (1), the reaction temperature is 90 to 220° C., preferably 120 to 200° C.; the reaction time is 5 to 300 minutes, preferably 10 to 240 minutes; And / or, the reaction in step (1) is carried out under an inert gas, and the inert gas pressure is 0.1 to 3.0 MPa, preferably 0.5 to 2.0 MPa.

5. The method according to claim 1, characterized in that: The solid acid catalyst in step (1) is selected from any one of SCM-36-SO3H molecular sieve, SCM-1-SO3H molecular sieve, H-beta molecular sieve, USY molecular sieve, sulfonated carbon or A-15 resin; preferably SCM-36-SO3H molecular sieve; Preferably, the SCM-36-SO3H molecular sieve, Acid / Lewis acid ratio is 2.2 to 4.0; Preferably, in the SCM-36-SO3H molecular sieve, the content of -SO3H is 1.9wt% to 18.0wt%; Preferably, the external specific surface area / total specific surface area of ​​the SCM-36-SO3H molecular sieve is 0.25 to 1, preferably 0.3 to 0.

7.

6. The method according to claim 1, characterized in that: The hydrogenolysis catalyst in step (2) is a precious metal and / or non-precious metal hydrogenation catalyst, including any one of Pd / C, Pt / C, Ru / C, Pd / Al2O3, Pt / Al2O3, Ru / Al2O3, Ru / Co3O4, Ni-Co3O4 / C, Ni-Al2O3, Ni-Fe / C or Ni-SCM-X; preferably Ni-SCM-X.

7. The method according to claim 6, characterized in that: In the Ni-SCM-X, X is 14 or 15; and / or, the Ni-SCM-X, based on the mass of SCM-X, has a Ni content of 0.2 wt% to 5.0 wt%, preferably 0.5 wt% to 3.0 wt%; And / or, in the Ni-SCM-X, the Si / Ge molar ratio of the SCM-X molecular sieve is 1.5-8, preferably 2-7.

8. The method according to claim 6 or 7, characterized in that: The total acid content of the Ni-SCM-X is 130 to 220 μmol·g -1 , preferably 150 to 200 μmol·g -1 ; and / or, the Ni-SCM-X The acid / Lewis acid ratio is 0.3 to 0.8, preferably 0.4 to 0.6; And / or, the molar ratio of metallic Ni to oxidized NiO in the Ni-SCM-X is 0.02 to 0.15, preferably 0.05 to 0.12; And / or, the average size of nickel particles in the Ni-SCM-X is 2 to 6 nm, preferably 3 to 5 nm.

9. The method according to claim 1, characterized in that: In step (2), the mass ratio of the organic solution containing 5-hydroxymethylfurfural and its passivation product obtained in step (1) to the hydrogenolysis catalyst is 30 to 200:1, preferably 50 to 150:

1.

10. The method according to claim 1, characterized in that: In step (2), hydrogen is charged into the reaction system to adjust the reaction pressure; the reaction pressure is 0.5 to 4.0 MPa, preferably 0.5 to 3.0 MPa. And / or, the reaction conditions of step (2) are as follows: the reaction temperature is 130-220° C., preferably 150-200° C.; the reaction time is 1-12 h, preferably 2-10 h.

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