A catalyst for preparing 2,5-dimethylfuran, its preparation method and application

Abstract

This invention discloses a catalyst for preparing 2,5-dimethylfuran, its preparation method, and its application. The catalyst comprises nickel, C3N4, and a support, wherein the support is activated carbon (HC); the oxygen content of the HC is 4 wt% to 18 wt%. The catalyst of this invention, when used in the reaction to prepare 2,5-dimethylfuran, exhibits high efficiency in the conversion of 5-hydroxymethylfurfural under mild reaction conditions, high selectivity for the product 2,5-dimethylfuran, and outstanding stability during catalyst recycling.

Description

Technical Field

[0001] This invention relates to the field of catalytic chemistry, specifically to a catalyst for the preparation of 2,5-dimethylfuran, its preparation method and application, particularly a catalyst for the catalytic conversion of 5-hydroxymethylfurfural to 2,5-dimethylfuran, its preparation method and application. Background Technology

[0002] With the advancement of science and technology and the development of society, human demand for traditional fossil energy sources such as coal, oil, and natural gas is increasing, leading to the depletion of fossil energy reserves on Earth. Furthermore, the combustion of fossil energy causes severe environmental pollution. Conversely, biomass, as a green and renewable energy source, is abundant on Earth, and its conversion and utilization process does not pollute the environment. Therefore, many scholars have focused on using biomass to supplement fossil energy. 2,5-Dimethylfuran (DMF), as an important product of biomass chemical conversion, has promising applications. It can be used as fuel, possessing a high energy density (31.5 MJ / L) and octane number (119). Compared with traditional bioethanol, DMF has significant advantages and is more suitable as a gasoline additive. Simultaneously, due to the presence of diene bonds on its furan ring, it can also undergo a Diels-Alder reaction (DA reaction) with monoolefins such as ethylene to directly synthesize bio-based p-xylene.

[0003] 2,5-Dimethylfuran (DMF) is mainly prepared by hydrogenolysis of 5-hydroxymethylfurfural (HMF). When hydrogen is used as the hydrogen source, commonly used catalysts include supported noble metals such as ruthenium (Ru), platinum (Pt), and palladium (Pd), as well as transition metals such as nickel (Ni), copper (Cu), and cobalt (Co). CN115007126A reports a method using Pd / AFC as a catalyst and formic acid as the hydrogen source, starting from HMF, achieving complete HMF conversion and a DMF yield as high as 95% after 15 h of reaction at 120 °C. CN114832833A reports a Pt single-atom catalyst supported on a Ni3Fe intermetallic compound, achieving a DMF yield as high as 99% under the conditions of 160 °C, 1 MPa H2, and HMF / Pt = 100 / 1. While the production of DMF from HMF in the presence of noble metal catalysts generally yields satisfactory results, the low reusability and high cost of noble metals severely hinder their commercial application. Therefore, the use of non-noble metals is gradually gaining attention from researchers. CN112742482A reports a reaction using a bimetallic (copper and cobalt) doped metal-organic framework compound (UIO-66-NH2) as a catalyst, HMF as a raw material, and 2-butanol as a hydrogen source. After reacting at 100°C for 4 hours, the product was analyzed to be 2,5-dihydroxymethylfuran (BHMF). 2,5-Dihydroxymethylfuran requires further deoxygenation and hydrogenation to obtain 2,5-dimethylfuran. CN112778243A reports that a NiFe / rGO catalyst does not require high-temperature pre-reduction treatment before use. Under conditions of 200°C, 2 MPa hydrogen pressure, and 2 wt% HMF concentration, a reaction time of 3 hours achieved 100% HMF conversion and 97% DMF yield and selectivity. Non-precious metal hydrogenation catalysts can achieve satisfactory results at lower HMF concentrations, but problems such as catalyst deactivation and easy loss of active components also exist.

[0004] In summary, existing technologies mainly suffer from problems such as low catalytic efficiency or poor catalyst cycle stability, which pose significant challenges to practical industrial applications. Summary of the Invention

[0005] The technical problem this invention aims to solve is the low catalytic efficiency or poor catalyst cycle stability existing in the prior art. It provides a catalyst for the preparation of 2,5-dimethylfuran, its preparation method, and its application. This catalyst, used in the reaction of 5-hydroxymethylfurfural to 2,5-dimethylfuran, exhibits high efficiency in the conversion of 5-hydroxymethylfurfural under mild reaction conditions, high selectivity for the product 2,5-dimethylfuran, and outstanding stability during catalyst cycle reuse.

[0006] The first aspect of the present invention provides a catalyst for preparing 2,5-dimethylfuran, wherein the catalyst comprises nickel, C3N4 and a support, wherein the support is activated carbon HC; the oxygen content of the HC is 4wt% to 18wt%, preferably 6wt% to 15wt%.

[0007] According to the present invention, the activated carbon HC is activated carbon activated by hydrogen.

[0008] According to the present invention, the catalyst is represented as Ni-C3N4 / HC.

[0009] According to the present invention, the catalyst, based on the support, has a nickel content of 0.5 wt% to 10 wt% (calculated as Ni); a C3N4 content of 2 wt% to 30 wt%; preferably, the nickel content is 1 wt% to 6 wt% (calculated as Ni); and / or, the C3N4 content is 4 wt% to 20 wt%.

[0010] According to the present invention, the total specific surface area of ​​the catalyst is 700–1800 m². 2 ·g -1 Preferably 800–1300m 2 ·g -1 .

[0011] According to the present invention, the molar ratio (Ni / NiO ratio) of metallic Ni to oxidized NiO in the catalyst is 0.35 to 0.70:1, preferably 0.40 to 0.65:1.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst for preparing 2,5-dimethylfuran. The preparation method includes the following steps:

[0013] The activated carbon was first activated in a hydrogen atmosphere, and then a nickel source and a nitrogen-containing precursor were loaded onto the hydrogen-activated activated carbon (HC). After drying, calcination and reduction, the catalyst was obtained.

[0014] According to the present invention, the loading method is preferably an impregnation method, specifically: a nickel source and a nitrogen-containing precursor are prepared into a solution, mixed with hydrogen-activated activated carbon (HC), and then dried, calcined and reduced to obtain the catalyst.

[0015] According to the present invention, the mass ratio of the nickel source (calculated as nickel), the nitrogen-containing precursor (calculated as the sum of the masses of C and N), the hydrogen-activated activated carbon (HC), and water is 0.004-0.2:0.02-0.40:1:1-10, preferably 0.008-0.1:0.05-0.30:1:2-8.

[0016] According to the present invention, in the method for preparing the catalyst, the activation temperature of the hydrogen is 500-1200°C, preferably 600-1000°C; the activation time is 2-12 hours, preferably 3-10 hours; the activation atmosphere is hydrogen or a hydrogen-argon mixture, wherein the volume fraction of hydrogen in the hydrogen-argon mixture is not less than 10%, preferably 10%-50%.

[0017] According to the present invention, in the method for preparing the catalyst, the drying temperature is 50–120°C, and the drying time is 4–12 h. The calcination temperature is 300–650°C, preferably 350–600°C; the calcination time is 1–12 h, preferably 2–6 h, and the calcination atmosphere is a non-oxygen gas atmosphere. The non-oxygen gas includes at least one of nitrogen and argon. The reduction temperature is 300–700°C, preferably 350–550°C; the reduction time is 1–12 h, preferably 2–6 h; the reduction atmosphere is hydrogen or a hydrogen-argon mixture, wherein the volume fraction of hydrogen in the hydrogen-argon mixture is not less than 10%, preferably 10%–50%.

[0018] According to the present invention, in the method for preparing the catalyst, the nickel source includes one or more of nickel nitrate, nickel acetate, nickel chloride, nickel acetylacetonate, and nickel sulfate, preferably at least one of nickel nitrate and nickel acetate.

[0019] According to the present invention, in the method for preparing the catalyst, the nitrogen-containing precursor includes one or more of urea, cyanoguanidine, and melamine, preferably at least one of urea and cyanoguanidine.

[0020] According to the present invention, the activated carbon includes at least one of coconut shell activated carbon and wood-based activated carbon, preferably coconut shell activated carbon. The total specific surface area of ​​the coconut shell activated carbon is 800-2000 m². 2 ·g -1 Preferably 900–1800m 2 ·g -1 The total specific surface area of ​​the hydrogen-activated carbon (HC) is 900–1800 m². 2 ·g -1 Preferably, it is 1100–1600m 2 ·g -1 The oxygen content of the coconut shell activated carbon is 20wt% to 40wt%, preferably 25wt% to 38wt%.

[0021] The third aspect of the present invention provides the application of the above-described catalyst or the catalyst prepared by the above-described method in the reaction of 5-hydroxymethylfurfural to 2,5-dimethylfuran.

[0022] According to the present invention, the method of application includes: 5-hydroxymethylfurfural reacting in the presence of the above catalyst with hydrogen as the hydrogen source to obtain 2,5-dimethylfuran.

[0023] According to the present invention, preferably, 5-hydroxymethylfurfural is dissolved in an organic solvent. More preferably, the organic solvent includes one or more of methanol, ethanol, n-butanol, tetrahydrofuran, 1,4-dioxane, and methyl isobutyl ketone, preferably at least one of tetrahydrofuran and n-butanol.

[0024] According to the present invention, the mass ratio of 5-hydroxymethylfurfural to catalyst is 0.2 to 20.0:1, preferably 0.5 to 10.0:1.

[0025] According to the present invention, the mass ratio of the organic solvent to 5-hydroxymethylfurfural is 20 to 300:1, preferably 50 to 200:1.

[0026] According to the present invention, hydrogen gas is introduced into the reaction system to adjust the reaction pressure. The reaction pressure is 0.5 to 6 MPa, preferably 1 to 5 MPa.

[0027] According to the present invention, the reaction conditions are as follows: the reaction temperature is 100-240°C, preferably 110-200°C; and / or the reaction time is 1-24 h, preferably 2-20 h.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The catalyst of the present invention is Ni-C3N4 / HC, and the oxygen content in HC is controlled. Preferably, the molar ratio of Ni / NiO in the active component is controlled. The catalyst has the characteristics of high efficiency in the conversion of 5-hydroxymethylfurfural and high selectivity for product 2,5-dimethylfuran under mild reaction conditions, as well as outstanding stability in the recycling of the catalyst.

[0030] (2) In the catalyst of the present invention, the activated carbon is first activated by hydrogen to control the oxygen content, and then modified by C3N4 and used in combination with Ni element. Preferably, the molar ratio of Ni / NiO in the catalyst is controlled. It has the characteristics of high efficiency of 5-hydroxymethylfurfural conversion under mild reaction conditions, high selectivity of product 2,5-dimethylfuran, and outstanding stability of catalyst recycling.

[0031] (3) The catalyst of this invention is used in the preparation of 2,5-dimethylfuran from 5-hydroxymethylfurfural. Under mild reaction conditions, 5-hydroxymethylfurfural can be efficiently converted to 2,5-dimethylfuran, with significantly improved substrate concentration, substrate conversion rate, and product selectivity. Simultaneously, the content of key impurities (e.g., 2,5-furandimethyl) in the obtained product is extremely low, greatly reducing separation energy consumption. Furthermore, this invention uses Ni-C3N4 / HC as the catalyst, exhibiting high stability; no significant change in catalyst performance was observed after four cycles of use. Attached Figure Description

[0032] Figure 1 The XRD pattern of the 1Ni-11C3N4 / HC catalyst in Example 1 is shown.

[0033] Figure 2 The image shows a SEM image of the 1Ni-11C3N4 / HC catalyst in Example 1.

[0034] Figure 3 The image shows the XPS plot of the 1Ni-11C3N4 / HC catalyst obtained in Example 1. Detailed Implementation

[0035] In this invention, the reaction product 2,5-dimethylfuran (DMF) was qualitatively analyzed by gas chromatography-mass spectrometry (GC-MS), and the conversion rate of the substrate 5-hydroxymethylfurfural (HMF) and the yield of the reaction product DMF were analyzed by gas chromatography (GC). The GC-MS system was an Agilent 7890A from Agilent Technologies, USA, with an HP-5 nonpolar capillary column (30m, 0.53mm). The gas chromatograph was an Agilent 7890B, with a flame ionization detector (FID) and an SE-54 capillary column (30m, 0.53mm).

[0036] In this invention, the XRD measurement method for the product is as follows: the phase composition of the sample is analyzed using a Rigaku Ultima IV X-ray powder diffractometer (Japan), with a CuKα ray source. Nickel filter, 2θ scanning range 2°-50°, operating voltage 35kV, current 25mA, scanning rate 10° / min.

[0037] In this invention, an inductively coupled plasma atomic emission spectrometer (ICP) of model Varian 725-ES is used to dissolve the analytical sample in hydrofluoric acid to detect the content of metal elements.

[0038] In this invention, the N2 adsorption-desorption (BET) isotherm of the sample was determined using a NOVA 1200e Surface Area & Pore Size Analyzer, and its specific surface area was obtained using the BET method. Before sample testing, the sample needs to be vacuum-treated at 200°C for 4 hours to remove moisture and volatile impurities from the catalyst surface.

[0039] In this invention, the element binding energy on the catalyst surface was measured on a Thermo X-ray photoelectron spectrometer (ESCA LAB-250), and the measured element signal was corrected using C1s = 284.6 eV as an internal standard.

[0040] In this invention, the conversion formula for 5-hydroxymethylfurfural is:

[0041] HMF conversion % = (molar amount of HMF participating in the reaction) / (molar amount of HMF substrate) × 100%.

[0042] In this invention, the formula for calculating the DMF selectivity of the product is:

[0043] Selectivity of product DMF % = (molar amount of DMF produced in the reaction) / (molar amount of HMF participating in the reaction) × 100%.

[0044] In this invention, the selectivity calculation formula for the byproduct 2,5-furandiethanol is as follows:

[0045] Selectivity % of 2,5-furandiethanol = (molar amount of 5-methylfurfural produced in the reaction) / (molar amount of HMF participating in the reaction) × 100%.

[0046] To facilitate understanding of the present invention, the following embodiments are provided. However, these embodiments are merely for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0047] Example 1

[0048] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 650℃ under a hydrogen atmosphere for 4 hours. The specific surface area of ​​HC was 1280 m². 2 ·g -1 The oxygen content is 11 wt%.

[0049] Under stirring conditions, 0.03 g of nickel nitrate and 0.22 g of urea were dissolved in 6 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon HC was then added for impregnation. The mass ratio of nickel nitrate (calculated as nickel), urea (calculated as the sum of C and N masses), hydrogen-activated carbon HC, and water was 0.009:0.15:1:6. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 450 °C under a hydrogen atmosphere for 4 hours to obtain the Ni-C3N4 / HC catalyst, in which the relative content of Ni was 1 wt% and the relative content of C3N4 was 11 wt%. The catalyst was named 1Ni-11C3N4 / HC.

[0050] BET test results show that the catalyst has a specific surface area of ​​1150 m². 2 ·g -1 The XRD pattern of the sample is as follows: Figure 1 As shown; SEM images of the samples are shown below. Figure 2 As shown; the XPS of the sample is as follows. Figure 3 As shown, a binding energy of 852.9 eV corresponds to the metallic element Ni(2p) 3 / 2 The peak), with a binding energy of 855.4 eV, corresponds to divalent nickel (2). + The molar ratio of metallic Ni to oxidized NiO is calculated using the ratio of the two peak areas (Ni / NiO ratio) and is 0.55.

[0051] Example 2

[0052] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 600℃ under a hydrogen atmosphere for 5 hours. The specific surface area of ​​HC was 1300 m². 2 ·g -1 The oxygen content is 12 wt%.

[0053] Under stirring conditions, 0.07 g of nickel nitrate and 0.25 g of urea were dissolved in 5 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon (HC) was then added for impregnation. The mass ratio of nickel nitrate (calculated as nickel), urea (calculated as the sum of C and N masses), hydrogen-activated carbon (HC), and water was 0.022:0.17:1:5. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 400 °C under a hydrogen atmosphere for 5 hours to obtain the Ni-C3N4 / HC catalyst, in which the relative content of Ni was 2 wt% and the relative content of C3N4 was 13 wt%. The catalyst was named 2Ni-13C3N4 / HC-A.

[0054] BET test results show that the catalyst has a specific surface area of ​​1038 m².2 ·g -1 XRD of the sample and Figure 1 Similar; the SEM of the sample is similar to Figure 2 Similar; the XPS of the sample is similar to Figure 3 Similarly, a binding energy of 852.9 eV corresponds to the metallic element Ni (2p0). 3 / 2 The peak), with a binding energy of 855.4 eV, corresponds to divalent nickel (2). + The molar ratio of metallic Ni to oxidized NiO is calculated using the ratio of the two peak areas (Ni / NiO ratio) and is 0.63.

[0055] Example 3

[0056] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 700℃ under a hydrogen atmosphere for 5 hours. The specific surface area of ​​HC was 1317 m². 2 ·g -1 The oxygen content is 10 wt%.

[0057] Under stirring conditions, 0.10 g of nickel nitrate and 0.16 g of urea were dissolved in 4 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon (HC) was then added for impregnation. The mass ratio of nickel nitrate (calculated as nickel), urea (calculated as the sum of C and N masses), hydrogen-activated carbon (HC), and water was 0.032:0.10:1:4. The impregnated product was dried at 80 °C for 5 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 450 °C under a hydrogen atmosphere for 4 hours to obtain the Ni-C3N4 / HC catalyst, wherein the relative content of Ni was 3 wt% and the relative content of C3N4 was 8 wt%. The catalyst was named 3Ni-8C3N4 / HC.

[0058] BET test results show that the catalyst has a specific surface area of ​​1080 m². 2 ·g -1 XRD of the sample and Figure 1 Similar; the SEM of the sample is similar to Figure 2 Similar; the XPS of the sample is similar to Figure 3 Similarly, a binding energy of 852.9 eV corresponds to the metallic element Ni (2p0). 3 / 2 The peak), with a binding energy of 855.4 eV, corresponds to divalent nickel (2). + The molar ratio of metallic Ni to oxidized NiO is calculated using the ratio of the two peak areas (Ni / NiO ratio) and is 0.47.

[0059] Example 4

[0060] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 800℃ under a hydrogen atmosphere for 6 hours. The specific surface area of ​​HC was 1263 m². 2 ·g -1 The oxygen content is 9 wt%.

[0061] Under stirring conditions, 0.12 g of nickel acetate and 0.14 g of cyanoguanidine were dissolved in 4 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon HC was then added for impregnation. The mass ratio of nickel acetate (calculated as nickel), cyanoguanidine (calculated as the sum of C and N masses), hydrogen-activated carbon HC, and water was 0.04:0.14:1:4. The impregnated product was dried at 80 °C for 5 hours, calcined at 550 °C under a nitrogen atmosphere for 5 hours, and reduced at 420 °C under a hydrogen atmosphere for 4 hours to obtain the Ni-C3N4 / HC catalyst, in which the relative content of Ni was 4 wt% and the relative content of C3N4 was 10 wt%. The catalyst was named 4Ni-10C3N4 / HC.

[0062] BET test results show that the catalyst has a specific surface area of ​​1040 m². 2 ·g -1 XRD of the sample and Figure 1 Similar; the SEM of the sample is similar to Figure 2 Similar; the XPS of the sample is similar to Figure 3 Similarly, a binding energy of 852.9 eV corresponds to the metallic element Ni (2p0). 3 / 2 The peak), with a binding energy of 855.4 eV, corresponds to divalent nickel (2). + The molar ratio of metallic Ni to oxidized NiO is calculated using the ratio of the two peak areas (Ni / NiO ratio) and is 0.53.

[0063] Example 5

[0064] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 680℃ under a hydrogen atmosphere for 6 hours. The specific surface area of ​​HC was 1322 m². 2 ·g -1 The oxygen content is 11 wt%.

[0065] Under stirring conditions, 0.09 g of nickel acetate and 0.15 g of cyanoguanidine were dissolved in 2 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon HC was then added for impregnation. The mass ratio of nickel acetate (calculated as nickel), cyanoguanidine (calculated as the sum of C and N masses), hydrogen-activated carbon HC, and water was 0.03:0.15:1:2. The impregnated product was dried at 90 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 450 °C under a hydrogen atmosphere for 4 hours to obtain the Ni-C3N4 / HC catalyst, in which the relative content of Ni was 3 wt% and the relative content of C3N4 was 11 wt%. The catalyst was named 3Ni-11C3N4 / HC.

[0066] BET test results show that the catalyst has a specific surface area of ​​1079 m². 2 ·g -1 XRD of the sample and Figure 1 Similar; the SEM of the sample is similar to Figure 2 Similar; the XPS of the sample is similar to Figure 3 Similarly, a binding energy of 852.9 eV corresponds to the metallic element Ni (2p0). 3 / 2 The peak), with a binding energy of 855.4 eV, corresponds to divalent nickel (2). + The molar ratio of metallic Ni to oxidized NiO is calculated using the ratio of the two peak areas (Ni / NiO ratio) and is 0.45.

[0067] Example 6

[0068] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 700℃ under a hydrogen atmosphere for 5 hours. The specific surface area of ​​HC was 1310 m². 2 ·g -1 The oxygen content is 10 wt%.

[0069] Under stirring conditions, 0.06 g of nickel acetate and 0.18 g of cyanoguanidine were dissolved in 5 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon HC was then added for impregnation. The mass ratio of nickel acetate (calculated as nickel), cyanoguanidine (calculated as the sum of C and N masses), hydrogen-activated carbon HC, and water was 0.02:0.18:1:5. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 430 °C under a hydrogen atmosphere for 5 hours to obtain the Ni-C3N4 / HC catalyst, in which the relative content of Ni was 2 wt% and the relative content of C3N4 was 13 wt%. The catalyst was named 2Ni-13C3N4 / HC-B.

[0070] BET test results show that the catalyst has a specific surface area of ​​1020 m².2 ·g -1 XRD of the sample and Figure 1 Similar; the SEM of the sample is similar to Figure 2 Similar; the XPS of the sample is similar to Figure 3 Similarly, a binding energy of 852.9 eV corresponds to the metallic element Ni (2p0). 3 / 2 The peak), with a binding energy of 855.4 eV, corresponds to divalent nickel (2). + The molar ratio of metallic Ni to oxidized NiO is calculated using the ratio of the two peak areas (Ni / NiO ratio) and is 0.62.

[0071] Example 7

[0072] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 780℃ in a hydrogen-argon mixed atmosphere (hydrogen integral of 20%) for 5 hours. The specific surface area of ​​HC was 1255 m². 2 ·g -1 The oxygen content is 12 wt%.

[0073] Under stirring conditions, 0.09 g of nickel acetate and 0.16 g of cyanoguanidine were dissolved in 6 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon HC was then added for impregnation. The mass ratio of nickel acetate (calculated as nickel), cyanoguanidine (calculated as the sum of C and N masses), hydrogen-activated carbon HC, and water was 0.03:0.16:1:6. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 470 °C under a hydrogen atmosphere for 4 hours to obtain the Ni-C3N4 / HC catalyst, in which the relative content of Ni was 3 wt% and the relative content of C3N4 was 12 wt%. The catalyst was named 3Ni-12C3N4 / HC.

[0074] BET test results show that the catalyst has a specific surface area of ​​1093 m². 2 ·g -1 XRD of the sample and Figure 1 Similar; the SEM of the sample is similar to Figure 2 Similar; the XPS of the sample is similar to Figure 3 Similarly, a binding energy of 852.9 eV corresponds to the metallic element Ni (2p0). 3 / 2 The peak), with a binding energy of 855.4 eV, corresponds to divalent nickel (2). + The molar ratio of metallic Ni to oxidized NiO is calculated using the ratio of the two peak areas (Ni / NiO ratio) and is 0.49.

[0075] Examples 8-14

[0076] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of tetrahydrofuran to HMF was 120, the hydrogen pressure was 1.5 MPa, the reaction temperature was 150℃, and the reaction time was 20 h.

[0077] 0.2 g of the catalyst from Examples 1-7 above, along with 0.2 g of HMF and 24.0 g of tetrahydrofuran, were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 150 °C for 20 h. The HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furandimethyl were calculated by gas phase analysis of the reaction liquid, as shown in Table 1.

[0078] Table 1 Catalytic evaluation results of catalysts in Examples 1-7

[0079]

[0080] Example 15

[0081] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of tetrahydrofuran to HMF was 100, the hydrogen pressure was 2 MPa, the reaction temperature was 160℃, and the reaction time was 15 h.

[0082] 0.2 g of the 1Ni-11C3N4 / HC catalyst from Example 1 above, 0.2 g of HMF, and 20 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 2 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 15 h. The HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furandimethyl were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

[0083] Example 16

[0084] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 2, the mass ratio of tetrahydrofuran to HMF was 150, the hydrogen pressure was 1.5 MPa, the reaction temperature was 150℃, and the reaction time was 20 h.

[0085] 0.2 g of the 1Ni-11C3N4 / HC catalyst from Example 1 above, 0.4 g of HMF, and 60 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 150 °C for 20 h. The HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furandimethyl were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

[0086] Example 17

[0087] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 2, the mass ratio of tetrahydrofuran to HMF was 80, the hydrogen pressure was 2 MPa, the reaction temperature was 170℃, and the reaction time was 12 h.

[0088] 0.2 g of the 1Ni-11C3N4 / HC catalyst from Example 1 above, 0.4 g of HMF, and 32 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 2 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 170 °C for 12 h. The HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furandimethyl were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

[0089] Example 18

[0090] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1.5, the mass ratio of tetrahydrofuran to HMF was 70, the hydrogen pressure was 3 MPa, the reaction temperature was 150℃, and the reaction time was 16 h.

[0091] 0.2 g of the 1Ni-11C3N4 / HC catalyst from Example 1 above, 0.3 g of HMF, and 21 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 3 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 150 °C for 16 h. The HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furandimethyl were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

[0092] Example 19

[0093] n-Butanol was used as the reaction solvent, the mass ratio of HMF to catalyst was 2, the mass ratio of n-butanol to HMF was 150, the hydrogen pressure was 3 MPa, the reaction temperature was 160℃, and the reaction time was 15 h.

[0094] 0.2 g of the 1Ni-11C3N4 / HC catalyst from Example 1 above, 0.4 g of HMF, and 60 g of n-butanol were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 3 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 160 °C for 15 h. The HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furandimethyl were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

[0095] Example 20

[0096] n-Butanol was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of n-butanol to HMF was 100, the hydrogen pressure was 2 MPa, the reaction temperature was 150℃, and the reaction time was 18 h.

[0097] 0.2 g of the 1Ni-11C3N4 / HC catalyst from Example 1 above, 0.2 g of HMF, and 20 g of n-butanol were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 2 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 150 °C for 18 h. The HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furandimethyl were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

[0098] To more intuitively describe the reaction conditions and results of Examples 15-20 above, the parameters and results are listed in Table 2.

[0099] Table 2 Catalytic performance results of Examples 15-20

[0100]

[0101]

[0102] Example 21

[0103] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of tetrahydrofuran to HMF was 120, the hydrogen pressure was 1.5 MPa, the reaction temperature was 150℃, and the reaction time was 20 h.

[0104] 0.2 g of the 1Ni-11C3N4 / HC catalyst from Example 1, 0.2 g of HMF, and 24 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 150 °C for 20 h. Gas phase analysis of the reaction liquid was performed to calculate the HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furandimethyl. The used catalyst was washed, dried, and then used in the next reaction cycle, for a total of 4 cycles. The results are shown in Table 3. The results show that after 4 reactions, HMF was completely converted (conversion rate > 99%), the DMF selectivity remained at 89.5%, and the selectivity of the key byproduct 2,5-furandimethyl was no greater than 0.5%, indicating that the 1Ni-11C3N4 / HC catalyst has good cycle stability.

[0105] Table 3 Catalyst Recycling Data

[0106]

[0107] Example 22

[0108] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 650℃ under a hydrogen atmosphere for 4 hours. The specific surface area of ​​HC was 1280 m². 2 ·g -1 The oxygen content is 11 wt%.

[0109] Under stirring conditions, 0.02 g of nickel nitrate and 0.06 g of urea were dissolved in 6 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon (HC) was then added for impregnation. The mass ratio of nickel nitrate (calculated as nickel), urea (calculated as the sum of C and N masses), hydrogen-activated carbon (HC), and water was 0.006:0.04:1:6. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 400 °C under a hydrogen atmosphere for 4 hours to obtain the Ni-C3N4 / HC catalyst, in which the relative content of Ni was 0.6 wt% and the relative content of C3N4 was 3 wt%. The catalyst was named 0.6Ni-3C3N4 / HC.

[0110] BET test results show that the catalyst has a specific surface area of ​​1150 m². 2 ·g -1 XRD of the sample and Figure 1 Similar; the SEM of the sample is similar to Figure 2 Similar; the XPS of the sample is similar to Figure 3 Similarly, a binding energy of 852.9 eV corresponds to the metallic element Ni (2p0). 3 / 2 The peak), with a binding energy of 855.4 eV, corresponds to divalent nickel (2). + The molar ratio of metallic Ni to oxidized NiO is calculated using the ratio of the two peak areas (Ni / NiO ratio) and is 0.38.

[0111] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of tetrahydrofuran to HMF was 120, the hydrogen pressure was 1.5 MPa, the reaction temperature was 150℃, and the reaction time was 20 h.

[0112] 0.2 g of the catalyst from Example 22 above, 0.2 g of HMF, and 24.0 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 150 °C for 20 h. Gas phase analysis of the reaction liquid showed that the HMF conversion was >99%, the DMF selectivity was 86.9%, and the selectivity of the key byproduct 2,5-furandimethyl was 0.5%. The used catalyst was washed, dried, and then used in the next reaction, for a total of 4 cycles. The results showed that after 4 reactions, HMF was completely converted (conversion rate >99%), the DMF selectivity remained at 84.7%, and the selectivity of the key byproduct 2,5-furandimethyl was 0.5% in all cases, indicating that the 0.6Ni-3C3N4 / HC catalyst has good cycle stability.

[0113] Example 23

[0114] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 700℃ under a hydrogen atmosphere for 5 hours. The specific surface area of ​​HC was 1317 m². 2 ·g -1 The oxygen content is 10 wt%.

[0115] Under stirring conditions, 0.21 g of nickel acetate and 0.27 g of cyanoguanidine were dissolved in 5 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon HC was then added for impregnation. The mass ratio of nickel acetate (calculated as nickel), cyanoguanidine (calculated as the sum of C and N masses), hydrogen-activated carbon HC, and water was 0.07:0.32:1:5. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 650 °C under a hydrogen atmosphere for 5 hours to obtain the Ni-C3N4 / HC catalyst, in which the relative content of Ni was 7 wt% and the relative content of C3N4 was 23 wt%. The catalyst was named 7Ni-23C3N4 / HC.

[0116] BET test results show that the catalyst has a specific surface area of ​​1020 m². 2 ·g -1 XRD of the sample and Figure 1 Similar; the SEM of the sample is similar to Figure 2 Similar; the XPS of the sample is similar to Figure 3 Similarly, a binding energy of 852.9 eV corresponds to the metallic element Ni (2p0). 3 / 2 The peak), with a binding energy of 855.4 eV, corresponds to divalent nickel (2). +The molar ratio of metallic Ni to oxidized NiO is calculated using the ratio of the two peak areas (Ni / NiO ratio) and is 0.68.

[0117] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of tetrahydrofuran to HMF was 120, the hydrogen pressure was 1.5 MPa, the reaction temperature was 150℃, and the reaction time was 20 h.

[0118] 0.2 g of the catalyst from Example 23 above, 0.2 g of HMF, and 24.0 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and then stirred magnetically. The reaction was carried out at 150 °C for 20 h. Gas phase analysis of the reaction liquid showed that the HMF conversion rate was >99%, the DMF selectivity was 87.7%, and the selectivity of the key byproduct 2,5-furandimethyl was 0.6%. The used catalyst was washed, dried, and then used in the next reaction, for a total of 4 cycles. The results showed that after 4 reactions, HMF was completely converted, the DMF selectivity remained at 85.4%, and the selectivity of the key byproduct 2,5-furandimethyl was 0.7% for all reactions, indicating that the 7Ni-23C3N4 / HC catalyst has good cycle stability.

[0119] Comparative Example 1

[0120] Under stirring conditions, 0.07 g of nickel nitrate and 0.25 g of urea were dissolved in 5 mL of aqueous solution and stirred until homogeneous. Then, 1 g of coconut shell activated carbon (with a specific surface area of ​​1350 m²) was added. 2 ·g -1 The catalyst was impregnated with nickel nitrate (calculated as nickel), urea (calculated as the total mass of C and N), activated carbon and water in a mass ratio of 0.022:0.17:1:5. The impregnated product was dried at 100°C for 5 hours, calcined at 500°C under a nitrogen atmosphere for 4 hours, and reduced at 400°C under a hydrogen atmosphere for 5 hours to obtain the Ni-C3N4 / C catalyst, in which the relative content of Ni was 2wt% and the relative content of C3N4 was 13wt%. The catalyst was named D-2Ni-13C3N4 / C.

[0121] BET test results show that the catalyst has a specific surface area of ​​1020 m². 2 ·g -1 XPS characterization of the sample showed that the molar ratio of metallic Ni to oxidized NiO was 0.31, calculated by the ratio of the two peak areas (Ni / NiO ratio).

[0122] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of tetrahydrofuran to HMF was 120, the hydrogen pressure was 1.5 MPa, the reaction temperature was 150℃, and the reaction time was 20 h.

[0123] 0.2 g of the D-2Ni-13C3N4 / C catalyst from Comparative Example 1, 0.2 g of HMF, and 24 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 150 °C for 20 h. Gas phase analysis of the reaction liquid showed complete conversion of HMF, a DMF selectivity of 78.3%, and a selectivity of 1.5% for the key byproduct 2,5-furandimethyl.

[0124] Comparative Example 2

[0125] Melamine was calcined at 550°C for 4 hours under a nitrogen atmosphere, and the resulting yellow powder was N-doped carbon C3N4.

[0126] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 650℃ under a hydrogen atmosphere for 4 hours. The specific surface area of ​​HC was 1280 m². 2 ·g -1 The oxygen content is 11 wt%.

[0127] Under stirring conditions, 0.06 g of nickel nitrate was dissolved in 3 mL of aqueous solution and stirred until homogeneous. Then, 0.13 g of C3N4 and 1 g of hydrogen-activated carbon HC were added for impregnation. The mass ratio of nickel nitrate (calculated as nickel), C3N4, hydrogen-activated carbon HC, and water was 0.02:0.13:1:3. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 400 °C under a hydrogen atmosphere for 5 hours to obtain the Ni / (HC-C3N4) catalyst, wherein the relative content of Ni was 2 wt% and the relative content of C3N4 was 13 wt%. The catalyst was named 2Ni / (HC-13C3N4).

[0128] BET test results show that the catalyst has a specific surface area of ​​1194 m². 2 ·g -1 XPS characterization of the sample showed that the molar ratio of metallic Ni to oxidized NiO was 0.84, calculated by the ratio of the two peak areas (Ni / NiO ratio).

[0129] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of tetrahydrofuran to HMF was 120, the hydrogen pressure was 1.5 MPa, the reaction temperature was 150℃, and the reaction time was 20 h.

[0130] 0.2 g of the 2Ni / (HC-13C3N4) catalyst from Comparative Example 2, 0.2 g of HMF, and 24 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 150 °C for 20 h. Gas phase analysis of the reaction liquid showed complete conversion of HMF, a DMF selectivity of 79.2%, and a selectivity of 2,5-furandimethyl for the key byproduct of 2.8%.

[0131] Comparative Example 3

[0132] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 650℃ under a hydrogen atmosphere for 4 hours. The specific surface area of ​​HC was 1280 m². 2 g -1 The oxygen content is 11 wt%.

[0133] Under stirring conditions, 0.06 g of nickel nitrate was dissolved in 3 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon (HC) was added for impregnation. The mass ratio of nickel nitrate (calculated as nickel), hydrogen-activated carbon (HC), and water was 0.02:1:3. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 400 °C under a hydrogen atmosphere for 5 hours to obtain the Ni / HC catalyst, wherein the relative Ni content was 2 wt%. The catalyst was named 2Ni / HC.

[0134] BET test results show that the catalyst has a specific surface area of ​​1255 m². 2 ·g -1 XPS characterization of the sample showed that the molar ratio of metallic Ni to oxidized NiO was 0.86, calculated by the ratio of the two peak areas (Ni / NiO ratio).

[0135] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of tetrahydrofuran to HMF was 120, the hydrogen pressure was 1.5 MPa, the reaction temperature was 150℃, and the reaction time was 20 h.

[0136] 0.2 g of the 2Ni / HC catalyst from Comparative Example 3, 0.2 g of HMF, and 24 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 150 °C for 20 h. Gas phase analysis of the reaction liquid showed complete conversion of HMF, a DMF selectivity of 49.7%, and a selectivity of 12.5% ​​for the key byproduct 2,5-furandimethyl.

[0137] Comparative Example 4

[0138] According to Chinese Patent (CN111346662A), nitrogen-doped activated carbon was synthesized using the following steps: Preparation of nitrogen-doped activated carbon: 1.8 mL of formaldehyde solution (mass fraction 37-40%) was diluted to 10-12 mL, the pH was adjusted to 9.5 with triethanolamine, 1 g of melamine was added, and the solution was dissolved by stirring in a water bath at 60°C. This solution was then added to 10 g of coconut shell activated carbon, kept at 60°C for 10 h, dried at 125°C, and calcined at 850°C for 2 h under nitrogen protection in an atmosphere furnace with a heating rate of 2-5°C / min to obtain nitrogen-doped activated carbon with a specific surface area of ​​1050 m². 2 ·g -1 .

[0139] Under stirring conditions, 0.06 g of nickel nitrate was dissolved in 3 mL of aqueous solution and stirred until homogeneous. 1 g of the above-mentioned nitrogen-doped activated carbon was added for impregnation. The mass ratio of nickel nitrate (calculated as nickel), nitrogen-doped activated carbon and water was 0.02:1:3. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 400 °C under a hydrogen atmosphere for 5 hours to obtain the Ni / NC catalyst, wherein the relative Ni content was 2 wt%. The catalyst was named 2Ni / NC.

[0140] BET test results show that the catalyst has a specific surface area of ​​983 m². 2 ·g -1 XPS characterization of the sample showed that the molar ratio of metallic Ni to oxidized NiO was 0.73, calculated by the ratio of the two peak areas (Ni / NiO ratio).

[0141] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of tetrahydrofuran to HMF was 120, the hydrogen pressure was 1.5 MPa, the reaction temperature was 150℃, and the reaction time was 20 h.

[0142] 0.2 g of the 2Ni / NC catalyst from Comparative Example 4, 0.2 g of HMF, and 24 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 150 °C for 20 h. Gas phase analysis of the reaction liquid showed complete HMF conversion, a DMF selectivity of 63.7%, and a selectivity of 7.6% for the key byproduct 2,5-furandimethyl.

[0143] Comparative Example 5

[0144] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was obtained by activation treatment at 650℃ under a hydrogen atmosphere for 4 hours. The specific surface area of ​​HC was 1280 m². 2 g -1 The oxygen content is 11 wt%.

[0145] Under stirring conditions, 0.03 g of nickel nitrate and 0.22 g of urea were dissolved in 6 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon HC was then added for impregnation. The mass ratio of nickel nitrate (calculated as nickel), urea (calculated as the sum of C and N masses), hydrogen-activated carbon HC, and water was 0.009:0.15:1:6. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 250 °C under a hydrogen atmosphere for 4 hours to obtain the Ni-C3N4 / HC catalyst, in which the relative content of Ni was 1 wt% and the relative content of C3N4 was 11 wt%. The catalyst was named D-1Ni-11C3N4 / HC.

[0146] BET test results show that the catalyst has a specific surface area of ​​1132 m². 2 ·g -1 XPS characterization of the sample showed that the molar ratio of metallic Ni to oxidized NiO was 0.18, calculated by the ratio of the two peak areas (Ni / NiO ratio).

[0147] Tetrahydrofuran was used as the reaction solvent, the mass ratio of HMF to catalyst was 1, the mass ratio of tetrahydrofuran to HMF was 120, the hydrogen pressure was 1.5 MPa, the reaction temperature was 150℃, and the reaction time was 20 h.

[0148] 0.2 g of the D-1Ni-11C3N4 / HC catalyst from Comparative Example 5, 0.2 g of HMF, and 24 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 150 °C for 20 h. Gas phase analysis of the reaction liquid showed complete conversion of HMF, a DMF selectivity of 69.1%, and a selectivity of 1.7% for the key byproduct 2,5-furandimethyl.

[0149] Comparative Example 6

[0150] Coconut shell activated carbon (specific surface area of ​​1350 m²) 2 ·g -1 Hydrogen-activated carbon (HC) with an oxygen content of 32 wt% was activated at 300°C in a hydrogen-argon mixed atmosphere (hydrogen integral of 20%) for 5 hours to obtain hydrogen-activated carbon. The specific surface area of ​​HC was 1305 m². 2 g -1 The oxygen content is 21 wt%.

[0151] Under stirring conditions, 0.09 g of nickel acetate and 0.16 g of cyanoguanidine were dissolved in 6 mL of aqueous solution and stirred until homogeneous. 1 g of hydrogen-activated carbon HC was then added for impregnation. The mass ratio of nickel nitrate (calculated as nickel), urea (calculated as the sum of C and N masses), hydrogen-activated carbon HC, and water was 0.03:0.16:1:6. The impregnated product was dried at 100 °C for 6 hours, calcined at 500 °C under a nitrogen atmosphere for 4 hours, and reduced at 470 °C under a hydrogen atmosphere for 4 hours to obtain the Ni-C3N4 / HC catalyst, in which the relative content of Ni was 3 wt% and the relative content of C3N4 was 12 wt%. The catalyst was named D-3Ni-12C3N4 / HC.

[0152] BET test results show that the catalyst has a specific surface area of ​​1210 m². 2 ·g -1 The molar ratio of metallic Ni to oxidized NiO in the obtained catalyst was calculated using the ratio of two peak areas (Ni / NiO ratio) and was 0.32.

[0153] 0.2 g of the D-3Ni-12C3N4 / HC catalyst from Comparative Example 6, 0.2 g of HMF, and 24 g of tetrahydrofuran were added to a high-pressure reactor equipped with a stirrer, and hydrogen gas was introduced at 1.5 MPa. The temperature was raised to the preset temperature using a programmed heating mantle, and the reactor was stirred magnetically. The reaction was carried out at 150 °C for 20 h. Gas phase analysis of the reaction liquid showed that the HMF conversion was >99%, the selectivity of the product DMF was 76.2%, and the selectivity of the key byproduct 2,5-furandimethyl was 3.2%.

[0154] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A catalyst for preparing 2,5-dimethylfuran, characterized in that, The catalyst comprises nickel, C3N4, and a support, wherein the support is activated carbon HC; the oxygen content of the HC is 4wt%~18wt%; the catalyst is expressed as Ni-C3N4 / HC; the catalyst, based on the mass of the support, has a nickel content of 0.5wt%~10wt% (calculated as Ni) and a C3N4 content of 2wt%~30wt%; the molar ratio of metallic Ni to oxidized NiO in the catalyst is 0.35~0.70:

1.

2. The catalyst according to claim 1, characterized in that, The oxygen content of the HC is 6wt%~15wt%.

3. The catalyst according to claim 1, characterized in that, The catalyst, based on the support mass, has a nickel content of 1wt% to 6wt% (calculated as Ni) and a C3N4 content of 4wt% to 20wt%.

4. The catalyst according to claim 1, characterized in that, The catalyst has a total specific surface area of ​​700~1800 m². 2 •g -1 .

5. The catalyst according to claim 4, characterized in that, The catalyst has a total specific surface area of ​​800~1300 m². 2 •g -1 .

6. The catalyst according to claim 1, characterized in that, The molar ratio of metallic Ni to oxidized NiO in the catalyst is 0.40~0.65:

1.

7. A method for preparing the catalyst according to any one of claims 1 to 6, comprising the following steps: The activated carbon is first activated at high temperature in a hydrogen atmosphere, and then a nickel source and a nitrogen-containing precursor are loaded onto the hydrogen-activated activated carbon. After drying, calcination and reduction, the catalyst is obtained.

8. The preparation method according to claim 7, characterized in that, The nickel source and nitrogen-containing precursor are first prepared into a solution, then mixed with activated carbon activated by hydrogen, and then dried, calcined and reduced to obtain the catalyst.

9. The preparation method according to claim 8, characterized in that, The nickel source is calculated as nickel, the nitrogen-containing precursor is calculated as the sum of C and N masses, and the mass ratio of activated carbon after hydrogen activation to water is 0.004~0.2:0.02~0.40:1:1~10.

10. The preparation method according to claim 9, characterized in that, The nickel source is calculated as nickel, the nitrogen-containing precursor is calculated as the sum of C and N masses, and the mass ratio of activated carbon after hydrogen activation to water is 0.008~0.1:0.05~0.30:1:2~8.

11. The preparation method according to claim 7, characterized in that, The hydrogen activation temperature is 500~1200℃; the activation time is 2~12h; and the activation atmosphere is hydrogen or a hydrogen-argon mixture.

12. The preparation method according to claim 11, characterized in that, The hydrogen activation temperature is 600~1000℃; the activation time is 3~10 hours.

13. The preparation method according to claim 7, characterized in that, The roasting temperature is 300~650℃; the roasting time is 1~12h; and the roasting atmosphere is a non-oxygen gas atmosphere.

14. The preparation method according to claim 13, characterized in that, The non-oxygen gas includes at least one of nitrogen and argon.

15. The preparation method according to claim 13, characterized in that, The roasting temperature is 350~600℃; the roasting time is 2~6h.

16. The preparation method according to claim 7, characterized in that, The reduction temperature is 300~700℃; the reduction time is 1~12h; and the reduction atmosphere is hydrogen or a hydrogen-argon mixture.

17. The preparation method according to claim 16, characterized in that, The reduction temperature is 350~550℃; the reduction time is 2~6h.

18. The preparation method according to claim 7, characterized in that, The nickel source includes one or more of nickel nitrate, nickel acetate, nickel chloride, nickel acetylacetonate, and nickel sulfate; And / or, the nitrogen-containing precursor includes one or more of urea, cyanoguanidine, and melamine.

19. The preparation method according to claim 18, characterized in that, The nickel source includes at least one of nickel nitrate and nickel acetate; And / or, the nitrogen-containing precursor includes at least one of urea and cyanoguanidine.

20. The preparation method according to claim 7, characterized in that, The activated carbon includes at least one of coconut shell activated carbon and wood activated carbon.

21. The preparation method according to claim 20, characterized in that, The activated carbon is coconut shell activated carbon.

22. The preparation method according to claim 21, characterized in that, The oxygen content of the coconut shell activated carbon is 20wt%~40wt%.

23. The preparation method according to claim 22, characterized in that, The oxygen content of the coconut shell activated carbon is 25wt%~38wt%.

24. The use of the catalyst according to any one of claims 1 to 6 or the catalyst prepared by the preparation method according to any one of claims 7 to 23 in the reaction of 5-hydroxymethylfurfural to 2,5-dimethylfuran.

Images