A method for preparing 2-methylfuran by catalytic transfer hydrogenation of furfural

Abstract

The present invention relates to the technical field of the preparation of 2-methylfuran, and particularly to a method for preparing 2-methylfuran by catalytic transfer hydrogenation of furfural. The method comprises the following steps: mixing furfural, a catalyst and a hydrogen donor, and reacting at 220-260 °C for 3-4.5 h to obtain 2-methylfuran. The catalyst is a Cu-Co@Silicalite-1 catalyst, the active components are Cu and Co, and the carrier is Silicalite-1; the Cu content in the catalyst is 2.8-5.1 wt%, and the Co content is 1.6-4 wt%. The present invention uses a non-noble metal catalyst to catalyze the transfer hydrogenation of furfural to prepare 2-MF, which has the advantages of simple process, zero hydrogen consumption and low catalyst cost compared with the existing process. In the present invention, the conversion rate of furfural reaches more than 90%, and the total molar yield of 2-MF can reach more than 80%.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of 2-methylfuran, and particularly relates to a method for preparing 2-methylfuran by catalytic transfer hydrogenation of furfural. Background Art

[0002] 2-Methylfuran (2-MF) is an important biomass platform compound and a basic chemical raw material, and has very important applications in the fields of pesticides, pharmaceuticals, and polymers. 2-MF can be prepared from non-grain crops such as Jerusalem artichokes and corn straws, and the raw material sources are rich. Moreover, due to the advantages of 2-MF such as high octane number, low mass, calorific value increased by about 16% relative to ethanol, and slightly soluble in water, it is considered to be one of the alternative fuels for internal combustion engines.

[0003] At present, the main method for industrial production of 2-MF is to catalytically hydrogenate furfural (furfuryl alcohol), but this method requires a large amount of hydrogen consumption and is often accompanied by high pressure, which has extremely high requirements for equipment and devices. Moreover, there are great safety hazards in the storage and transportation of H2. Once an accident occurs, it has unimaginable destructive power. In terms of large-scale hydrogen production, most use coal, petroleum, etc., which cause environmental pollution and are not conducive to the realization of the carbon neutrality goal. In addition, the main catalyst used in industrial production of 2-MF is a Cu-Cr system catalyst, which is expensive, and Cr is toxic and will cause serious environmental pollution. Therefore, using a hydrogen donor as the hydrogen source for hydrogen production and using a cheaper and more environmentally friendly catalyst have become the research goals of more and more scientific researchers.

[0004] At present, some literatures have reported relevant work on the in-situ hydrogenation of furfural to prepare 2-MF. Xiaohai Yang et al. (Chem Cat Chem 2017, 9, 3023-3030) used a Cu / ZnO catalyst for the hydrogenation of furfural to 2-methylfuran (2-MF). Under appropriate reaction conditions, 2-MF with a yield of 76.9% can be obtained, and the product yield needs to be improved. Kuo Ke et al. (ACS Sustainable Chem. Eng. 2020, 8, 16624-16636) used a Cu-Re / Al2O3 catalyst for the hydrogenation of furfural to 2-methylfuran (2-MF). When reacting at 220 °C for 4 hours, the yield of 2-methylfuran reaches 93%, but Re is a precious metal and is expensive. Based on the above content, there is an urgent need for a catalyst and method for catalytic hydrogenation of furfural to prepare 2-methylfuran with better catalytic effects. Summary of the Invention

[0005] Based on the above, the present invention provides a method for preparing 2-methylfuran by catalytic transfer hydrogenation of furfural. The entire reaction process is easy to operate. Without external hydrogen, the hydrogen comes from the hydrogen donor, greatly reducing hydrogen consumption and reaction risks. The catalyst uses a non-noble metal catalyst, reducing environmental pollution and harm to the human body.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is a catalyst for preparing 2-methylfuran by catalytic transfer hydrogenation of furfural. The catalyst is a Cu-Co@Silicalite-1 catalyst, the active components are Cu and Co, and the carrier is Silicalite-1; the Cu content in the catalyst is 3-6 wt%, and the Co content is 2-6 wt%.

[0008] Another technical solution of the present invention is a preparation method of the above catalyst for preparing 2-methylfuran by catalytic transfer hydrogenation of furfural, including the following steps:

[0009] Step 1, adding a copper salt and a cobalt salt into an alkali solution and mixing evenly, and then adding a silicon source and a template agent to obtain a gel;

[0010] Step 2, subjecting the gel to crystallization treatment, and then calcining to obtain catalyst A;

[0011] Step 3, performing ion exchange on catalyst A to obtain the catalyst for preparing 2-methylfuran by catalytic transfer hydrogenation of furfural.

[0012] Further, in step 1, the copper salt is copper nitrate; the cobalt salt is cobalt nitrate; the silicon source is silica sol; the template agent is tetrapropylammonium hydroxide; the mass ratio of the copper salt, cobalt salt and silicon source is 0.116-0.232:0.116-0.33:3; the pH of the gel ≥ 13; the alkali solution is an aqueous sodium hydroxide solution with a pH of not less than 13.

[0013] The mass ratio of the alkali solution to the silicon source is 5.5-6:1; the mass ratio of the template agent to the silicon source is 0.4:1.

[0014] Further, in step 2, the crystallization treatment temperature is: 140-200 °C; the crystallization treatment time is 24-72 h; the calcination specifically is: calcining at 550 °C for 3-8 h; before the calcination, there are also steps of filtration, washing, and drying for 10-15 h.

[0015] Preferably, the calcination time is 6 h.

[0016] Preferably, the crystallization treatment temperature is 140 °C, and the crystallization treatment time is 72 h.

[0017] Too high crystallization temperature will lead to serious metal clusters and cause a decline in catalytic performance. Too low temperature cannot achieve the technical purpose of crystallization. Through experimental verification, the catalyst synthesized under the conditions of 140-200 °C and 12-72 h in the present invention can catalyze the conversion of furfural to 2-methylfuran. The condition of 140 °C and 72 h can enable the product to achieve the best catalytic performance, with a furfural conversion rate of 96% and a 2-methylfuran yield of 90%.

[0018] Preferably, the drying temperature is 12 h.

[0019] Further, in step 3, the catalyst A is placed in a 1 g / L ammonium chloride / ammonium hydroxide solution (pH = 10-11, preferably pH = 10.5) for ion exchange; the concentration of the catalyst A in the ammonium chloride / ammonium hydroxide solution is 1 mol / L.

[0020] Further, the temperature of the ion exchange is 80 °C, the time is 2-5 h, and the number of ion exchange times is 2-3 times.

[0021] The third technical solution of the present invention is a method for preparing 2-methylfuran by catalytic transfer hydrogenation of furfural. Using furfural and a hydrogen donor as raw materials, the reaction is carried out under the catalytic conditions of the above catalyst to obtain 2-methylfuran.

[0022] Further, it includes the following steps: Mix furfural, the above catalyst and the hydrogen donor and react at 220-260 °C for 3-4.5 h to obtain 2-methylfuran.

[0023] The specific reaction formula is as follows:

[0024]

[0025] Further, the hydrogen donor is isopropanol; the mass-volume ratio of furfural, the catalyst and the hydrogen donor is: 0.03 g: 0.01-0.03 g: 3 mL.

[0026] The present invention discloses the following technical effects:

[0027] 1) The catalyst raw materials in the present invention are cheap and the preparation method is simple.

[0028] 2) The catalyst in the present invention does not contain toxic metal Cr, reduces environmental pollution and human harm, and has high activity and selectivity.

[0029] 3) The catalyst of the present invention can obtain a higher metal (Cu and Co) loading amount, and can meet the requirements for a high-loading metal doping system.

[0030] 4) The present invention modifies Silicalite-1 through ion exchange under alkaline conditions, so that after modification, Silicalite-1 has strong Brønsted and strong Lewis acid sites, thereby making the prepared catalyst have better catalytic performance; the prepared catalyst can replace the existing zeolites containing Al, Ti (with strong and strong Lewis acid sites), etc. and be applied to the hydrogenation of furfural to prepare 2-methylfuran, achieving better catalytic performance and product yield.

[0031] 5) The present invention uses a non-noble metal catalyst to catalyze the catalytic transfer hydrogenation of furfural to prepare 2-MF, which has the advantages of simple process, zero hydrogen consumption, and low catalyst cost compared with the existing process.

[0032] 6) In the present invention, the conversion rate of furfural reaches up to 100%, and the total molar yield of 2-MF can reach more than 80%, with the highest yield being 96%. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0034] Figure 1 XRD characterization data of the catalyst 5.1Cu-2.8Co@Silicalite-1 (H-Cu-Co@Silcalite-1) prepared in Example 1.

[0035] Figure 2 STEM-EDS diagram of the catalyst 5.1Cu-2.8Co@Silicalite-1 prepared in Example 1.

[0036] Figure 3 Cu 2p orbitals of the catalysts Na-5.1Cu-2.8Co@Silcalite-1 and H-5.1Cu-2.8Co@Silcalite-1 (catalyst 5.1Cu-2.8Co@Silicalite-1) prepared in Example 1; among them, the left figure is the Na type and the right figure is the H type. DETAILED DESCRIPTION OF THE INVENTION

[0037] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the present invention.

[0038] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. Additionally, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0039] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the said documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0040] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of the present invention are merely exemplary.

[0041] Regarding "comprising", "including", "having", "containing", etc. used herein, they are all open-ended terms, meaning including but not limited to.

[0042] The "%" mentioned in the present invention represents mass percentage unless otherwise specified.

[0043] Unless otherwise specified, the raw materials used in the embodiments of the present invention can be obtained through commercial channels.

[0044] The silica sol concentration used in the embodiments of the present invention is 30 wt%.

[0045] In the embodiments of the present invention, the recovery of the catalyst is carried out through simple filtration and drying steps.

[0046] In the embodiments of the present invention, furfural and 2-MF are quantitatively analyzed by GC-FID. The specific analysis conditions are as follows: the chromatographic column is an Agilent HP-5 capillary column (30 m × 0.32 mm × 0.25 μm), the injection temperature: 300 °C; the injection volume: 1 μL; the split ratio: 10:1; the FID detection temperature: 320 °C; the programmed temperature rise: hold at 30 °C for 4 minutes, then rise to 140 °C at a rate of 10 °C per minute, and then rise to 300 °C at a rate of 20 °C per minute.

[0047] The calculation methods of relevant parameters are as follows:

[0048]

[0049]

[0050] Example 1

[0051] Step 1: Dissolve 0.71 g of NaOH in 16.12 g of distilled water, then add 1.2 g of TPAOH (tetrapropylammonium hydroxide), and stir vigorously for 0.5 h. After that, add 0.232 g of Cu(NO3)2·2.5H2O and 0.23 g of Co(NO3)2·6H2O. After stirring for 1 hour, slowly drop 3 g of silica sol into the above mixture under stirring. A homogeneous solid gel is formed after 2 hours. The pH of the reaction system is about 14.

[0052] Step 2: Transfer the above solid gel into a reaction kettle and react at 140 °C for 72 h. Filter and dry. Then calcine in a muffle furnace at 550 °C for 6 h, denoted as Na-Cu-Co@Silcalite-1.

[0053] Step 3: Ion-exchange Na-Cu-Co@Silcalite-1 twice in an ammonium chloride / ammonium hydroxide solution (concentration: 1 g / L, pH value = 10.5) (the concentration of Na-Cu-Co@Silcalite-1 in the solution is 1 mol / L, the ion-exchange temperature is 80 °C, and the ion-exchange time is 3 hours) to obtain the catalyst 5.1Cu-2.8Co@Silicalite-1 (the numbers in front of Cu and Co represent the actual metal loading amount, unit wt%, and the calculation method is: loading amount = metal / carrier × 100%).

[0054] Step 4: Mix 0.03 g of furfural, 0.015 g of the catalyst 5.1Cu-2.8Co@Silicalite-1 with 3 mL of isopropanol and place them in a 14 mL stainless steel batch reactor, and seal it properly. Heat the oven to 240 °C, place the reaction kettle in the oven, the reaction time is 3 - 4.5 h, cool the reaction product, and after dissolving with an organic solvent, perform GC-FID respectively. The furfural conversion rate and 2-MF yield at different reaction times are shown in Table 1:

[0055] Table 1 Furfural conversion rate and 2-MF yield at different reaction times

[0056] Reaction time / h Furfural conversion rate (%) 2-MF yield (%) 3 90 81 3.5 96 90 4 100 89 4.5 100 85

[0057] As can be seen from Table 1, when 5.1Cu-2.8Co@Silicalite-1 is used as the catalyst, under the reaction conditions of 240 °C, the furfural conversion rate reaches 96% at 3.5 h, and the 2-MF yield reaches the maximum (90%). After extending the reaction time, the 2-MF yield decreases because extending the time will convert 2-methylfuran into 2-pentanol.

[0058] Comparative Example 1

[0059] The difference from Example 1 is only that the addition of NaOH in Step 1 is omitted, and the pH of the reaction system is about 8.9.

[0060] The catalyst 5.1Cu-2.8Co@Silicalite-1 synthesized in this comparative example was used in the reaction of preparing 2-methylfuran from furfural by catalytic transfer hydrogenation. The furfural conversion rate and 2-MF yield at different reaction times are shown in Table 2:

[0061] Table 2 Furfural conversion rate and 2-MF yield at different reaction times

[0062] Reaction time / h Furfural conversion rate (%) 2-MF yield (%) 3 9 0.5 3.5 23 1 4 36 3 4.5 40 7

[0063] From the data in Table 2, it can be concluded that when the pH value of the reaction in Step 1 is not controlled to be a strong base condition, both the furfural conversion rate and the 2-MF yield are relatively low. The reason is that a higher content of metal can be loaded under high pH values, that is, there are more active sites.

[0064] Comparative Example 2

[0065] The difference from Example 1 is only that Step 3 is omitted. That is, Na-Cu-Co@Silcalite-1 is obtained, and Na-Cu-Co@Silcalite-1 is used in the reaction of preparing 2-methylfuran from furfural by catalytic transfer hydrogenation. The furfural conversion rate and 2-MF yield at different reaction times are shown in Table 3:

[0066] Table 3 Furfural conversion rate and 2-MF yield at different reaction times

[0067] Reaction time / h Furfural conversion rate (%) 2-MF yield (%) 3 20 2 3.5 55 8 4 61 22 4.5 72 32

[0068] From the data in Table 3, it can be concluded that by omitting the ion exchange process under basic conditions in Step 3, both the furfural conversion rate and the 2-MF yield are relatively low. The reason is that a higher content of metal can be loaded under strong base conditions, that is, there are more active sites, so the catalytic activity is stronger under strong base conditions. Omitting the ion exchange process under basic conditions makes it impossible to load a higher content of metal, with fewer active sites and poor catalytic activity.

[0069] Comparative Example 3

[0070] At room temperature, 4.3 g of copper nitrate, concentrated ammonia water, and deionized water were mixed to form a mixture with a pH of 9.5 - 12.5. 5.75 g of powdered aluminum oxide was added thereto, and the mixture was stirred at room temperature for 12 h. The temperature was raised to 120 °C, and the pH value of the mixed solution was monitored in real time until it decreased to 6 - 7 and then the process ended. It was filtered and washed with deionized water. The obtained solid sample was dried in an oven at 100 °C for 6 h, and then transferred to a muffle furnace and calcined at 650 °C for 3 h to obtain a catalyst precursor (Cu / Al2O3).

[0071] 2.0 g of the prepared catalyst precursor Cu / Al2O3 was weighed and impregnated in an equal volume in an aqueous solution containing cobalt nitrate for 36 hours, and then dried in an oven at 100 °C for 6 h. Then it was transferred to a muffle furnace and calcined at 650 °C for 6 h. The components in the obtained catalyst B were Cu - Co / Al2O3.

[0072] The above catalyst was reduced at 350 °C for 1 h, the reduction pressure was 0.3 MPa, the reducing gas was hydrogen, and the gas hourly space velocity was 3000 h -1 . After the reduction was completed, it was cooled to room temperature to obtain the final catalyst.

[0073] 0.03 g of furfural, 0.015 g of the final catalyst, and 3 mL of isopropanol were mixed and placed in a 14 mL stainless - steel batch reactor, and it was properly sealed. The oven was heated to 240 °C, the reaction kettle was placed in the oven, the reaction time was 3.5 h, the reaction product was cooled, and after being dissolved in an organic solvent, GC - FID was carried out respectively. As a result, the furfural conversion rate was 64%, and the 2 - MF yield was 36%.

[0074] Example 2

[0075] Step 1: 0.71 g of NaOH was dissolved in 16.12 g of distilled water, then 1.2 g of TPAOH was added, and it was stirred vigorously for 0.5 h. Then 0.232 g of Cu(NO3)2·2.5H2O and 0.23 g of Co(NO3)2·6H2O were added. After stirring for 1 hour, 3 g of silica sol was slowly dropped into the above mixture under stirring, and a homogeneous solid gel was formed after 2 hours. The pH of the reaction system was about 14.

[0076] Step 2: The above solid gel was transferred into a reaction kettle and reacted at 140 °C for 72 h. It was filtered and dried. Then it was calcined in a muffle furnace at 550 °C for 6 h, denoted as Na - Cu - Co@Silcalite - 1.

[0077] Step 3: Ion-exchange Na-Cu-Co@Silcalite-1 in an ammonium chloride / ammonium hydroxide solution (concentration: 1 g / L, pH value = 10.5), with a concentration of 1 mol / L, a temperature of 80 °C, a reaction time of 3 hours, and the number of times being 2. Thus, the catalyst 5.1Cu-2.8Co@Silicalite-1 is obtained (the content of Steps 1-3 is the same as that in Example 1).

[0078] Step 4: Mix 0.03 g of furfural, 0.01 - 0.1 g of the catalyst 5.1Cu-2.8Co@Silicalite-1 with 3 mL of isopropanol, place them in a 14 mL stainless-steel batch reactor, and seal it properly. Heat the oven to 180 - 260 °C, place the reaction kettle in the oven, with a reaction time of 3 - 4.5 h. Cool the reaction product, dissolve it with an organic solvent, and then perform GC-FID respectively. The furfural conversion rate and 2-MF yield under different reaction temperatures, reaction times, and catalyst dosages are shown in Table 4:

[0079] Table 4 Furfural conversion rate and 2-MF yield under different reaction temperatures, reaction times, and catalyst dosages

[0080]

[0081]

[0082] Example 3

[0083] Step 1: Dissolve 0.71 g of NaOH in 16.12 g of distilled water, then add 1.2 g of TPAOH, stir vigorously for 0.5 h, and then add 0.116 - 0.232 g of Cu(NO3)2·2.5H2O and 0.116 - 0.33 g of Co(NO3)2·6H2O. After stirring for 1 hour, slowly drop 3 g of silica sol into the above mixture under stirring. A homogeneous solid gel is formed after 2 hours. The pH of the reaction system is about 14.

[0084] Step 2: Transfer the above solid gel into a reaction kettle, react at 140 °C for 72 h. Filter, filter again, and dry. Then calcine it in a muffle furnace at 550 °C for 6 h, denoted as Na-Cu-Co@Silcelite-1.

[0085] Step 3: Ion-exchange Na-Cu-Co@Silcelite-1 in an ammonium chloride / ammonium hydroxide solution (concentration: 1 g / L, pH value = 10.5), with a concentration of 1 mol / L, a temperature of 80 °C, a reaction time of 3 hours, and the number of times being 2. Thus, the catalyst H-Cu-Co@Silicalite-1 (Cu-Co@Silicalite-1) is obtained.

[0086] Step 4: Mix 0.03 g of furfural, 0.015 g of catalyst H-Cu-Co@Silicalite-1 with 3 mL of isopropanol, and place the mixture in a 14-mL stainless-steel batch reactor, then seal it properly. Heat the oven to 240 °C, place the reaction kettle in the oven, react for 3.5 h, cool the reaction product, and perform GC-FID after dissolving in organic solvents. The furfural conversion rate and 2-MF yield at 240 °C / 3.5 h with different Cu-Co contents are shown in Table 5:

[0087] Table 5 Furfural conversion rate and 2-MF yield at 240 °C / 3.5 h with different H-Cu-Co contents

[0088] xCu-yCo@Silicalite-1 Furfural conversion rate (%) 2-MF yield (%) 0.116Cu-0.116Co 96 80 0.166Cu-0.116Co 96 81 0.232Cu-0.116Co 94 83 0.282Cu-0.116Co 95 83 0.232Cu-0.116Co 95 83 0.232Cu-0.166Co 96 84 0.232Cu-0.232Co 96 90 0.232Cu-0.282Co 95 92

[0089] Note: In Table 5, "g" in gCu-gCo represents the metal feeding amount.

[0090] Example 4

[0091] The catalyst was prepared by the same preparation method as in Steps 1-3 of Example 1, except that the added masses of Cu(NO3)2·2.5H2O and Co(NO3)2·6H2O were adjusted to obtain different catalysts: a) 3Cu-2@Silicalite-1; b) 3.9Cu-2Co@Silicalite-1; c) 4.9Cu-2Co@Silicalite-1; d) 5.9Cu-2Co@Silicalite-1; e) 5.9Cu-2.6Co@Silicalite-1; f) 5.9Cu-3.1Co@Silicalite-1; g) 5.9Cu-3.8Co@Silicalite-1; h) 5.9Cu-4.5Co@Silicalite-1;

[0092] Table 6 shows the ICP-OES characterization results of different catalysts a); b); c); d); e); f); g); h); It can be concluded that the actual Cu and Co masses of the catalyst 5.9Cu-3.1Co@Silicalite-1 are 1.82:1, which is not much different from the results obtained by EDS. One of the possible reasons for the error is that EDS only takes a very small area for quantitative analysis of elements, which may be slightly deviated from the actual results; another possible reason is that the precipitation rates of different metals in the solution are inconsistent and not completely precipitated by 100%, resulting in the actual Cu and Co content ratios being slightly lower than the theoretical values.

[0093] Table 6 ICP-OES characterization results of different catalysts

[0094] Entry Cu (%) (actual) Co% (actual) Cu(Co)% (theoretical) a 2.8 1.6 3(2) b 3.5 1.6 3.9(2) c 4.6 1.6 4.9(2) d 5.1 1.5 5.9(2) e 5.1 3.2 5.9(2.6) f 5.1 2.8 5.9(3.1) g 4.9 3.4 5.9(3.8) h 4.9 4 5.9(4.5)

[0095] The above catalyst was used in the reaction of catalytic transfer hydrogenation of furfural to prepare 2-methylfuran. The specific process was the same as that in Step 4 of Example 1, and the catalytic performance is shown in Table 7.

[0096] Table 7 Furfural conversion and 2-MF yield of catalysts with different metal contents at 240 °C / 3.5 h

[0097] Entry Furfural conversion rate (%) 2-MF yield (%) a 90 80 b 92 82 c 94 86 d 96 90 e 94 92 f 96 84 g 96 82 h 93 81

[0098] Catalyst characterization

[0099] Figure 1 The XRD characterization data of the catalyst 5.1Cu-2.8Co@Silicalite-1 (H-Cu-Co@Silcalite-1) prepared in Example 1 are as follows. Figure 1 It can be seen that after ion exchange under alkaline conditions, Na-Cu-Co@Silicalite-1 (Catalyst A) becomes H-Cu-Co@Silicalite-1, but still shows the diffraction characteristic peaks of Silicalite-1. This indicates that the crystal structure has not changed after treatment.

[0100] Figure 2 The STEM-EDS diagram of the catalyst 5.1Cu-2.8Co@Silicalite-1 prepared in Example 1 is shown below. Figure 2 It can be seen that the Cu and Co elements in the catalyst 5.1Cu-2.8Co@Silicalite-1 are evenly distributed, while the Si and O elements are evenly distributed throughout the electron microscope field of view.

[0101] Figure 3 The Cu 2p orbitals of the catalysts Na-Cu-Co@Silcalite-1 (Catalyst A) and H-Cu-Co@Silicalite-1 (Catalyst 5.1Cu-2.8Co@Silicalite-1) prepared in Example 1 are shown below. The Cu 2p of the Na-type catalyst can be divided into three peaks, and the binding energies are 932.67 eV, 934.37 eV, and 936.75 eV, which are attributed to Cu 0 、Cu 1+ 、Cu 2+ , respectively, among which the content of Cu 1+ is the highest. The Cu 2p of the H-type catalyst is divided into two peaks, and the binding energies are 932.54 eV and 934.56 eV, which are attributed to Cu 0 、Cu 1+ .

[0102] In the present invention, a non-noble metal catalyst Cu-Co@Silicalite-1 is used to catalyze the preparation of 2-MF from furfural by catalytic transfer hydrogenation. Compared with the existing process, it has the advantages of simple process, zero hydrogen consumption, low catalyst cost, etc., and improves the conversion rate of furfural and the total molar yield of 2-MF.

[0103] The embodiments described above are only used to describe the preferred mode of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A catalyst for the preparation of 2-methylfuran by catalytic transfer hydrogenation of furfural, characterized in that, The catalyst is a Cu-Co@Silicalite-1 catalyst, with the active components being Cu and Co, and the carrier being Silicalite-1; the Cu content in the catalyst is 2.8 - 5.1 wt%, and the Co content is 1.6 - 4 wt%; The preparation method of the catalyst for the catalytic transfer hydrogenation of furfural to prepare 2-methylfuran is as follows: Step 1, adding copper salt and cobalt salt into an alkali solution and mixing evenly, then adding a silicon source and a template agent to obtain a gel; Step 2, subjecting the gel to crystallization treatment and then calcining to obtain catalyst A; Step 3, performing ion exchange on catalyst A to obtain the catalyst for the catalytic transfer hydrogenation of furfural to prepare 2-methylfuran; Catalyst A is placed in a 1 g / L ammonium chloride / ammonium hydroxide solution for ion exchange; the concentration of catalyst A in the ammonium chloride / ammonium hydroxide solution is 1 mol / L; The pH value of the ammonium chloride / ammonium hydroxide solution is 10 - 11; the temperature of the ion exchange is 80 °C, the time is 2 - 5 h, and the number of ion exchange times is 2 - 3 times.

2. The catalyst according to claim 1, wherein In Step 1, the copper salt is copper nitrate; the cobalt salt is cobalt nitrate; the silicon source is silica sol; the template agent is tetrapropylammonium hydroxide; the mass ratio of the copper salt, cobalt salt and silicon source is 0.116 - 0.232:0.116 - 0.33:3; the pH of the gel is not less than 13; the alkali solution is a sodium hydroxide aqueous solution with a pH not less than 13.

3. The catalyst according to claim 1, characterized in that, In Step 2, the crystallization treatment temperature is: 140 - 200 °C; the crystallization treatment time is 24 - 72 h; the calcination specifically is: calcining at 550 °C for 3 - 8 h; before the calcination, there are also steps of filtration, washing and drying.

4. A method for preparing 2-methylfuran by catalytic transfer hydrogenation of furfural, characterized in that, Using furfural and a hydrogen donor as raw materials, reacting under the catalytic conditions of the catalyst described in Claim 1 to obtain 2-methylfuran.

5. The method according to claim 4, characterized in that, Including the following steps: Mixing furfural, the catalyst described in Claim 1 and a hydrogen donor, and reacting at 220 - 260 °C for 3 - 4.5 h to obtain 2-methylfuran.

6. The method according to claim 5, wherein The hydrogen donor is isopropanol; the mass-volume ratio of furfural, the catalyst and the hydrogen donor is: 0.03 g:0.01 - 0.03 g:3 mL.

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