Catalyst for preparing 2, 5-dimethylfuran as well as preparation method and application of catalyst

Abstract

The invention discloses a catalyst for preparing 2, 5-dimethylfuran as well as a preparation method and application of the catalyst. The catalyst comprises nickel, C3N4 and a carrier, and the carrier is activated carbon HC; the oxygen content of the HC ranges from 4 wt% to 18 wt%. The catalyst provided by the invention is used in a reaction for preparing 2, 5-dimethylfuran, and has the characteristics of efficient conversion of 5-hydroxymethylfurfural under mild reaction conditions, high selectivity of the product 2, 5-dimethylfuran, outstanding recycling stability of the catalyst and the like.

Description

Technical Field

[0001] The present invention relates to the field of catalytic chemistry, and in particular to a catalyst for preparing 2,5-dimethylfuran, a preparation method and application thereof, and in particular to a catalyst for catalytically converting 5-hydroxymethylfurfural to prepare 2,5-dimethylfuran, a preparation method and application thereof. 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 supported 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. CN115007126A reported that Pd / AFC was used as a catalyst and formic acid was used as a hydrogen source. After reacting at 120°C for 15h, HMF was completely converted and the DMF yield was as high as 95%. CN114832833A reported that Pt single-atom catalysts supported by Ni3Fe intermetallic compounds had a DMF yield of up to 99% under the conditions of 160°C, 1MPa H2, and HMF / Pt=100 / 1. In the presence of noble metal catalysts, HMF production of DMF can usually obtain satisfactory results, but the low reusability and high cost of noble metals seriously hinder their commercial application, so the use of non-noble metals has gradually received attention from researchers. CN112742482A reported that a metal organic framework compound (UIO-66-NH2) doped with bimetallic (copper and cobalt) was used as a catalyst, HMF was used as a raw material, and 2-butanol was used 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 needs to be further deoxygenated and hydrogenated to obtain 2,5-dimethylfuran. CN112778243A reported that the NiFe / rGO catalyst does not need to be subjected to high-temperature pre-reduction treatment before use. It reacts for 3 hours at 200°C, 2MPa hydrogen pressure, and 2wt% HMF concentration. The conversion rate of HMF can reach 100%, and the yield and selectivity of DMF can reach 97%. Non-precious metal hydrogenation catalysts can achieve satisfactory results at lower HMF concentrations, but there are also problems such as catalyst deactivation and easy loss of active components.

[0004] In summary, the existing technologies mainly have problems such as low catalytic efficiency or poor catalyst cycle stability, which brings great problems to practical industrial applications. Summary of the invention

[0005] The technical problem to be solved by the present invention is the low catalytic efficiency or poor catalyst cycle stability in the prior art, and a catalyst for preparing 2,5-dimethylfuran and a preparation method and application thereof are provided. The catalyst is used in the reaction of catalyzing 5-hydroxymethylfurfural to prepare 2,5-dimethylfuran, and has the characteristics of efficient conversion of 5-hydroxymethylfurfural under mild reaction conditions and high selectivity of the product 2,5-dimethylfuran, as well as outstanding stability in catalyst cycle use.

[0006] The first aspect of the present invention provides a catalyst for preparing 2,5-dimethylfuran, wherein the catalyst comprises nickel, C3N4 and a carrier, the carrier 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 by Ni-C3N4 / HC.

[0009] According to the present invention, the catalyst, based on the carrier, has a nickel content of 0.5wt% to 10wt% in terms of Ni; a C3N4 content of 2wt% to 30wt%; preferably, the nickel content of 1wt% to 6wt% in terms of Ni; and / or a C3N4 content of 4wt% to 20wt%.

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

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

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

[0013] The activated carbon is firstly activated in a hydrogen atmosphere, and then a nickel source and a nitrogen-containing precursor are loaded on the activated carbon (HC) activated by hydrogen, and then dried, calcined and reduced to obtain the catalyst.

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

[0015] According to the present invention, the mass ratio of the nickel source (in terms of nickel), the nitrogen-containing precursor (in terms of the sum of the masses of C and N), the activated carbon (HC) activated by hydrogen 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 preparation method of the catalyst, the temperature of hydrogen activation is 500-1200°C, preferably 600-1000°C; the activation time is 2-12h, preferably 3-10h; 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 preparation method of the catalyst, the drying temperature is 50-120°C, and the drying time is 4-12h. The calcination temperature is 300-650°C, preferably 350-600°C; the calcination time is 1-12h, preferably 2-6h, 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 1-12h, preferably 2-6h; the reduction atmosphere is hydrogen or a hydrogen-argon mixed gas, and the volume fraction of hydrogen in the hydrogen-argon mixed gas 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 comprises at least one of coconut shell activated carbon and wood activated carbon, preferably coconut shell activated carbon. The total specific surface area of ​​the coconut shell activated carbon is 800 to 2000 m 2 ·g -1 , preferably 900~1800m 2 ·g -1 The total specific surface area of ​​the hydrogen activated carbon (HC) is 900 to 1800 m 2 ·g -1 , preferably 1100~1600m 2 ·g -1 The coconut shell activated carbon has an oxygen content of 20 wt% to 40 wt%, preferably 25 wt% to 38 wt%.

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

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

[0023] According to the present invention, preferably, 5-hydroxymethylfurfural is dissolved in an organic solvent. Further preferably, the organic solvent comprises 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 0.2-20.0:1, preferably 0.5-10.0:1.

[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 is charged into the reaction system to adjust the reaction pressure, which 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 to 240° C., preferably 110 to 200° C.; and / or the reaction time is 1 to 24 hours, preferably 2 to 20 hours.

[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 efficient conversion of 5-hydroxymethylfurfural and high selectivity of the product 2,5-dimethylfuran under mild reaction conditions, and outstanding stability in catalyst recycling.

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

[0031] (3) The catalyst of the present invention is used for the reaction of preparing 2,5-dimethylfuran from 5-hydroxymethylfurfural. Under mild reaction conditions, 5-hydroxymethylfurfural can be efficiently converted into 2,5-dimethylfuran, and the substrate concentration, substrate conversion rate and product selectivity are significantly improved. At the same time, the content of key impurities (such as 2,5-furan dimethanol) in the obtained product is extremely low, which greatly reduces the separation energy consumption. In addition, the present invention has high stability by using Ni-C3N4 / HC as a catalyst, and no significant change in catalyst performance is observed after four cycles. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0033] Figure 2 is the SEM image of the 1Ni-11C3N4 / HC catalyst in Example 1;

[0034] Figure 3 This is the XPS graph of the 1Ni-11C3N4 / HC catalyst obtained in Example 1. DETAILED DESCRIPTION

[0035] In the present invention, the reaction product 2,5-dimethylfuran (DMF) is qualitatively analyzed by gas chromatography-mass spectrometry (GC-MS), and the conversion rate of substrate 5-hydroxymethylfurfural (HMF) and the yield of the reaction product DMF are analyzed by gas chromatography (GC). The gas chromatography-mass spectrometry instrument is Agilent 7890A of Agilent Corporation of the United States, the chromatographic column is HP-5 non-polar capillary column (30m, 0.53mm), the gas chromatograph is Agilent 7890B, the detector is a hydrogen flame ionization detector (FID), and the chromatographic column is SE-54 capillary column (30m, 0.53mm).

[0036] In the present invention, the product XRD measurement method is: using Japanese 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.

[0037] 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.

[0038] In the present invention, N2 adsorption-desorption (BET) is performed using a NOVA 1200e Surface Area & Pore Size Analyzer to measure the N2 adsorption-desorption isotherm of the sample, and the specific surface area is obtained using the BET method. Before the sample is tested, it is necessary to vacuum treat at 200°C for 4 hours to remove moisture and volatile impurities on the catalyst surface.

[0039] In the present invention, the determination of the element binding energy on the catalyst surface is carried out on an X-ray photoelectron spectrometer (ESCA LAB-250) produced by Thermo Company, using C1s=284.6eV as an internal standard to calibrate the measured element signal.

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

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

[0042] In the present invention, the product DMF selectivity calculation formula is:

[0043] The selectivity of the product DMF (%) = (the molar amount of DMF generated by the reaction) / (the molar amount of HMF participating in the reaction) × 100%.

[0044] In the present invention, the by-product 2,5-furan dimethanol selectivity calculation formula is:

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

[0046] 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.

[0047] Example 1

[0048] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated at 650℃ in hydrogen atmosphere for 4 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1280m 2 ·g -1 , the oxygen content is 11wt%.

[0049] Under stirring conditions, 0.03 g of nickel nitrate and 0.22 g of urea are dissolved in 6 mL of aqueous solution and stirred evenly, and 1 g of activated carbon HC activated by hydrogen is added for impregnation, wherein the mass ratio of nickel nitrate (in terms of nickel), urea (in terms of the total mass of C and N), activated carbon HC activated by hydrogen and water is: 0.009:0.15:1:6, and the impregnated product is dried at 100° C. for 6 hours, calcined at 500° C. for 4 hours in a nitrogen atmosphere, and reduced at 450° C. for 4 hours in a hydrogen atmosphere to obtain a Ni-C3N4 / HC catalyst, wherein the relative content of Ni is 1wt%, the relative content of C3N4 is 11wt%, and the catalyst is named 1Ni-11C3N4 / HC.

[0050] The BET test results show that the specific surface area of ​​the catalyst is 1150m 2 ·g -1 ; XRD of the sample is as follows Figure 1 As shown; SEM of the sample is as Figure 2 As shown; the XPS of the sample is as Figure 3 As shown, the binding energy at 852.9 eV corresponds to the metal 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 was calculated by the ratio of the two peak areas (Ni / NiO ratio) and was 0.55.

[0051] Example 2

[0052] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated in a hydrogen atmosphere at 600℃ for 5 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1300m 2 ·g -1 , the oxygen content is 12wt%.

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

[0054] The BET test results show that the specific surface area of ​​the catalyst is 1038m2 ·g -1 ; XRD and Figure 1 Similar; SEM and Figure 2 Similar; XPS and Figure 3 Similarly, the binding energy at 852.9 eV corresponds to the metal 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 was calculated by the ratio of the two peak areas (Ni / NiO ratio) and was 0.63.

[0055] Example 3

[0056] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated in a hydrogen atmosphere at 700℃ for 5 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1317m 2 ·g -1 , the oxygen content is 10wt%.

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

[0058] The BET test results show that the specific surface area of ​​the catalyst is 1080 m 2 ·g -1 ; XRD and Figure 1 Similar; SEM and Figure 2 Similar; XPS and Figure 3 Similarly, the binding energy at 852.9 eV corresponds to the metal 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 was calculated by the ratio of the two peak areas (Ni / NiO ratio) and was 0.47.

[0059] Example 4

[0060] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated in hydrogen atmosphere at 800℃ for 6 hours, to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1263m 2 ·g -1 , the oxygen content is 9wt%.

[0061] Under stirring conditions, 0.12g of nickel acetate and 0.14g of cyanoguanidine are dissolved in 4mL of aqueous solution and stirred evenly, and 1g of activated carbon HC activated by hydrogen is added for impregnation, wherein the mass ratio of nickel acetate (in terms of nickel), cyanoguanidine (in terms of the total mass of C and N), hydrogen-activated activated carbon HC and water is: 0.04:0.14:1:4, and the impregnated product is dried at 80°C for 5 hours, calcined at 550°C in a nitrogen atmosphere for 5 hours, and reduced at 420°C in a hydrogen atmosphere for 4 hours to obtain a Ni-C3N4 / HC catalyst, wherein the relative content of Ni is 4wt%, the relative content of C3N4 is 10wt%, and the catalyst is named 4Ni-10C3N4 / HC.

[0062] The BET test results show that the specific surface area of ​​the catalyst is 1040 m 2 ·g -1 ; XRD and Figure 1 Similar; SEM and Figure 2 Similar; XPS and Figure 3 Similarly, the binding energy at 852.9 eV corresponds to the metal 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 was calculated by the ratio of the two peak areas (Ni / NiO ratio) and was 0.53.

[0063] Example 5

[0064] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated in a hydrogen atmosphere at 680℃ for 6 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1322m 2 ·g -1 , the oxygen content is 11wt%.

[0065] Under stirring conditions, 0.09 g of nickel acetate and 0.15 g of cyanoguanidine are dissolved in 2 mL of aqueous solution and stirred evenly, and 1 g of activated carbon HC activated by hydrogen is added for impregnation, wherein the mass ratio of nickel acetate (in terms of nickel), cyanoguanidine (in terms of the total mass of C and N), activated carbon HC activated by hydrogen and water is: 0.03:0.15:1:2, and the impregnated product is dried at 90° C. for 6 hours, calcined at 500° C. for 4 hours in a nitrogen atmosphere, and reduced at 450° C. for 4 hours in a hydrogen atmosphere to obtain a Ni-C3N4 / HC catalyst, wherein the relative content of Ni is 3wt%, the relative content of C3N4 is 11wt%, and the catalyst is named 3Ni-11C3N4 / HC.

[0066] The BET test results show that the specific surface area of ​​the catalyst is 1079 m 2 ·g -1 ; XRD and Figure 1 Similar; SEM and Figure 2 Similar; XPS and Figure 3 Similarly, the binding energy at 852.9 eV corresponds to the metal 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 was calculated by the ratio of the two peak areas (Ni / NiO ratio) and was 0.45.

[0067] Example 6

[0068] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated in a hydrogen atmosphere at 700℃ for 5 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1310m 2 ·g -1 , the oxygen content is 10wt%.

[0069] Under stirring conditions, 0.06g of nickel acetate and 0.18g of cyanoguanidine are dissolved in 5mL of aqueous solution and stirred evenly, and 1g of activated carbon HC activated by hydrogen is added for impregnation, wherein the mass ratio of nickel acetate (in terms of nickel), cyanoguanidine (in terms of the total mass of C and N), hydrogen-activated activated carbon HC and water is: 0.02:0.18:1:5, and the impregnated product is dried at 100°C for 6 hours, calcined at 500°C in a nitrogen atmosphere for 4 hours, and reduced at 430°C in a hydrogen atmosphere for 5 hours to obtain a Ni-C3N4 / HC catalyst, wherein the relative content of Ni is 2wt%, the relative content of C3N4 is 13wt%, and the catalyst is named 2Ni-13C3N4 / HC-B.

[0070] The BET test results show that the specific surface area of ​​the catalyst is 1020m2 ·g -1 ; XRD and Figure 1 Similar; SEM and Figure 2 Similar; XPS and Figure 3 Similarly, the binding energy at 852.9 eV corresponds to the metal 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 was calculated by the ratio of the two peak areas (Ni / NiO ratio) and was 0.62.

[0071] Example 7

[0072] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated at 780℃ in a hydrogen-argon mixed atmosphere (hydrogen gas volume fraction is 20%) for 5 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1255m 2 ·g -1 , the oxygen content is 12wt%.

[0073] Under stirring conditions, 0.09g of nickel acetate and 0.16g of cyanoguanidine are dissolved in 6mL of aqueous solution and stirred evenly, and 1g of activated carbon HC activated by hydrogen is added for impregnation, wherein the mass ratio of nickel acetate (in terms of nickel), cyanoguanidine (in terms of the total mass of C and N), hydrogen-activated activated carbon HC and water is: 0.03:0.16:1:6, and the impregnated product is dried at 100°C for 6 hours, calcined at 500°C in a nitrogen atmosphere for 4 hours, and reduced at 470°C in a hydrogen atmosphere for 4 hours to obtain a Ni-C3N4 / HC catalyst, wherein the relative content of Ni is 3wt%, the relative content of C3N4 is 12wt%, and the catalyst is named 3Ni-12C3N4 / HC.

[0074] The BET test results show that the specific surface area of ​​the catalyst is 1093m 2 ·g -1 ; XRD and Figure 1 Similar; SEM and Figure 2 Similar; XPS and Figure 3 Similarly, the binding energy at 852.9 eV corresponds to the metal 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 was calculated by the ratio of the two peak areas (Ni / NiO ratio) and was 0.49.

[0075] Embodiment 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° C., and the reaction time was 20 h.

[0077] 0.2 g of the catalyst in the above-mentioned Examples 1-7, 0.2 g of HMF and 24.0 g of tetrahydrofuran were added to a stirred autoclave, and 1.5 MPa of hydrogen was charged. 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 150° C. for 20 h, and the HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furan dimethanol were calculated by gas phase analysis of the reaction liquid, as shown in Table 1.

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

[0079]

[0080] Embodiment 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° C., and the reaction time was 15 h.

[0082] 0.2g of the 1Ni-11C3N4 / HC catalyst in Example 1, 0.2g of HMF and 20g of tetrahydrofuran were added to a stirred autoclave, and 2MPa 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 160°C for 15h, and the HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furan dimethanol 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° C., and the reaction time was 20 h.

[0085] 0.2g of the 1Ni-11C3N4 / HC catalyst in Example 1, 0.4g of HMF and 60g of tetrahydrofuran 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 150°C for 20h, and the HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furan dimethanol were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

[0086] Embodiment 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° C., and the reaction time was 12 h.

[0088] 0.2g of the 1Ni-11C3N4 / HC catalyst in Example 1, 0.4g of HMF and 32g of tetrahydrofuran were added to a stirred autoclave, and 2MPa 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 170°C for 12h, and the HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furan dimethanol were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

[0089] Embodiment 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° C., and the reaction time was 16 h.

[0091] 0.2g of the 1Ni-11C3N4 / HC catalyst in Example 1, 0.3g of HMF and 21g of tetrahydrofuran were added to a stirred autoclave, and 3MPa 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 150°C for 16h, and the HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furan dimethanol were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

[0092] Embodiment 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°C, and the reaction time was 15 h.

[0094] 0.2g of the 1Ni-11C3N4 / HC catalyst in the above Example 1, 0.4g of HMF and 60g of n-butanol were added to a stirred autoclave, and 3MPa 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 160°C for 15h, and the HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furan dimethanol were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

[0095] Embodiment 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°C, and the reaction time was 18 h.

[0097] 0.2g of the 1Ni-11C3N4 / HC catalyst in Example 1, 0.2g of HMF and 20g of n-butanol were added to a stirred autoclave, and 2MPa 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 150°C for 18h, and the HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furan dimethanol were calculated by gas phase analysis of the reaction liquid, as shown in Table 2.

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

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

[0100]

[0101]

[0102] Embodiment 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° C., and the reaction time was 20 h.

[0104] 0.2g of the 1Ni-11C3N4 / HC catalyst in the above-mentioned Example 1, 0.2g of HMF and 24g of tetrahydrofuran were added to a stirred autoclave, and 1.5MPa of hydrogen was filled. The temperature was raised to a preset temperature using a program heating jacket, and then stirred using magnetic stirring. The reaction was carried out at 150°C for 20h, and the HMF conversion rate and the selectivity of the product DMF and the key byproduct 2,5-furan dimethanol were analyzed and calculated by gas phase analysis of the reaction liquid. The used catalyst was washed and dried and then put into the next reaction, and the reaction was circulated for 4 times. The results are shown in Table 3. The results show that after 4 reactions, HMF was completely converted (conversion rate>99%), the DMF selectivity was maintained at 89.5%, and the selectivity of the key byproduct 2,5-furan dimethanol was not greater than 0.5%, indicating that the 1Ni-11C3N4 / HC catalyst has good cyclic stability.

[0105] Table 3 Catalyst recycling data

[0106]

[0107] Embodiment 22

[0108] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated at 650℃ in hydrogen atmosphere for 4 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1280m 2 ·g -1 , the oxygen content is 11wt%.

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

[0110] The BET test results show that the specific surface area of ​​the catalyst is 1150m 2 ·g -1 ; XRD and Figure 1 Similar; SEM and Figure 2 Similar; XPS and Figure 3 Similarly, the binding energy at 852.9 eV corresponds to the metal 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 was calculated by the ratio of the two peak areas (Ni / NiO ratio) and was 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° C., and the reaction time was 20 h.

[0112] 0.2g of the catalyst in Example 22, 0.2g of HMF and 24.0g of tetrahydrofuran were added to a stirred autoclave, and 1.5MPa of hydrogen was charged. The temperature was raised to a preset temperature using a program heating jacket, and then stirred using magnetic stirring. The reaction was carried out at 150°C for 20h, and the HMF conversion rate was calculated to be >99%, the product DMF selectivity was 86.9%, and the selectivity of the key by-product 2,5-furan dimethanol was 0.5%. The used catalyst was washed and dried and then put into the next reaction, and the reaction was circulated for 4 times. The results showed that after 4 reactions, HMF was completely converted (conversion rate>99%), the DMF selectivity was maintained at 84.7%, and the selectivity of the key by-product 2,5-furan dimethanol was 0.5%, indicating that the 0.6Ni-3C3N4 / HC catalyst has good cyclic stability.

[0113] Embodiment 23

[0114] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated in a hydrogen atmosphere at 700℃ for 5 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1317m 2 ·g -1 , the oxygen content is 10wt%.

[0115] Under stirring conditions, 0.21g of nickel acetate and 0.27g of cyanoguanidine are dissolved in 5mL of aqueous solution and stirred evenly, and 1g of activated carbon HC activated by hydrogen is added for impregnation, wherein the mass ratio of nickel acetate (in terms of nickel), cyanoguanidine (in terms of the total mass of C and N), hydrogen-activated activated carbon HC and water is: 0.07:0.32:1:5, and the impregnated product is dried at 100°C for 6 hours, calcined at 500°C in a nitrogen atmosphere for 4 hours, and reduced at 650°C in a hydrogen atmosphere for 5 hours to obtain a Ni-C3N4 / HC catalyst, wherein the relative content of Ni is 7wt%, the relative content of C3N4 is 23wt%, and the catalyst is named 7Ni-23C3N4 / HC.

[0116] The BET test results show that the specific surface area of ​​the catalyst is 1020m 2 ·g -1 ; XRD and Figure 1 Similar; SEM and Figure 2 Similar; XPS and Figure 3 Similarly, the binding energy at 852.9 eV corresponds to the metal 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 was calculated by the ratio of the two peak areas (Ni / NiO ratio) and was 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° C., and the reaction time was 20 h.

[0118] 0.2g of the catalyst in Example 23, 0.2g of HMF and 24.0g of tetrahydrofuran were added to a stirred autoclave, and 1.5MPa of hydrogen was added. The temperature was raised to a preset temperature using a program heating jacket, and then stirred using magnetic stirring. The reaction was carried out at 150°C for 20h, and the HMF conversion rate was calculated by gas phase analysis of the reaction liquid>99%, the product DMF selectivity was 87.7%, and the selectivity of the key by-product 2,5-furan dimethanol was 0.6%. The used catalyst was washed and dried and then put into the next reaction, and the reaction was circulated for 4 times. The results showed that after 4 reactions, HMF was completely converted, the DMF selectivity was maintained at 85.4%, and the selectivity of the key by-product 2,5-furan dimethanol was 0.7%, indicating that the 7Ni-23C3N4 / HC catalyst has good cyclic stability.

[0119] Comparative Example 1

[0120] Under stirring conditions, 0.07 g nickel nitrate and 0.25 g urea were dissolved in 5 mL aqueous solution and stirred evenly. 1 g coconut shell activated carbon (with a specific surface area of ​​1350 m 2 ·g -1 , oxygen content is 32wt%) for impregnation, wherein the mass ratio of nickel nitrate (in terms of nickel), urea (in terms of the total mass of C and N), activated carbon and water is: 0.022:0.17:1:5, the impregnated product is dried at 100°C for 5 hours, calcined at 500°C in a nitrogen atmosphere for 4 hours, and reduced at 400°C in a hydrogen atmosphere for 5 hours to obtain a Ni-C3N4 / C catalyst, wherein the relative content of Ni is 2wt%, the relative content of C3N4 is 13wt%, and the catalyst is named D-2Ni-13C3N4 / C.

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

[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° C., and the reaction time was 20 h.

[0123] 0.2g of the D-2Ni-13C3N4 / C catalyst in the above comparative example 1, 0.2g of HMF and 24g of tetrahydrofuran were added to a stirred autoclave, and 1.5MPa of hydrogen was charged. 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 150°C for 20h, and the HMF conversion was completely calculated by gas phase analysis of the reaction liquid, the product DMF selectivity was 78.3%, and the selectivity of the key byproduct 2,5-furan dimethanol was 1.5%.

[0124] Comparative Example 2

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

[0126] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated at 650℃ in hydrogen atmosphere for 4 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1280m 2 ·g -1 , the oxygen content is 11wt%.

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

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

[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° C., and the reaction time was 20 h.

[0130] 0.2g of the 2Ni / (HC-13C3N4) catalyst in Comparative Example 2, 0.2g of HMF and 24g of tetrahydrofuran 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 150°C for 20h, and the HMF conversion was completely calculated by gas phase analysis of the reaction liquid, the product DMF selectivity was 79.2%, and the selectivity of the key byproduct 2,5-furan dimethanol was 2.8%.

[0131] Comparative Example 3

[0132] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated at 650℃ in hydrogen atmosphere for 4 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1280m 2 g -1 , the oxygen content is 11wt%.

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

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

[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° C., and the reaction time was 20 h.

[0136] 0.2g of the 2Ni / HC catalyst in Comparative Example 3, 0.2g of HMF and 24g of tetrahydrofuran 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 150°C for 20h, and the HMF conversion was completely calculated by gas phase analysis of the reaction liquid, the product DMF selectivity was 49.7%, and the selectivity of the key byproduct 2,5-furan dimethanol was 12.5%.

[0137] Comparative Example 4

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

[0139] Under stirring conditions, 0.06 g of nickel nitrate was dissolved in 3 mL of aqueous solution and stirred evenly, and 1 g of the above-mentioned nitrogen-doped activated carbon was added for impregnation, wherein the mass ratio of nickel nitrate (in terms of 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 in a nitrogen atmosphere for 4 hours, and reduced at 400°C in a hydrogen atmosphere for 5 hours to obtain a Ni / NC catalyst, wherein the relative content of Ni was 2wt%, and the catalyst was named 2Ni / NC.

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

[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° C., and the reaction time was 20 h.

[0142] 0.2g of the 2Ni / NC catalyst in Comparative Example 4, 0.2g of HMF and 24g of tetrahydrofuran 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 150°C for 20h, and the HMF conversion was completely calculated by gas phase analysis of the reaction liquid, the product DMF selectivity was 63.7%, and the selectivity of the key byproduct 2,5-furan dimethanol was 7.6%.

[0143] Comparative Example 5

[0144] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated at 650℃ in hydrogen atmosphere for 4 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1280m 2 g -1 , the oxygen content is 11wt%.

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

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

[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° C., and the reaction time was 20 h.

[0148] 0.2g of D-1Ni-11C3N4 / HC catalyst in the above comparative example 5, 0.2g of HMF and 24g of tetrahydrofuran were added to a stirred autoclave, and 1.5MPa of hydrogen was charged. 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 150°C for 20h, and the HMF conversion was completely calculated by gas phase analysis of the reaction liquid, the selectivity of the product DMF was 69.1%, and the selectivity of the key byproduct 2,5-furan dimethanol was 1.7%.

[0149] Comparative Example 6

[0150] Coconut shell activated carbon (specific surface area 1350m 2 ·g -1 , oxygen content is 32wt%), activated in a hydrogen-argon mixed atmosphere (hydrogen gas volume fraction is 20%) at 300℃ for 5 hours to obtain hydrogen activated activated carbon HC, the specific surface area of ​​HC is 1305m 2 g -1 , the oxygen content is 21wt%.

[0151] Under stirring conditions, 0.09g of nickel acetate and 0.16g of cyanoguanidine are dissolved in 6mL of aqueous solution and stirred evenly, and 1g of activated carbon HC activated by hydrogen is added for impregnation, wherein the mass ratio of nickel nitrate (in terms of nickel), urea (in terms of the total mass of C and N), activated carbon HC activated by hydrogen and water is: 0.03:0.16:1:6, and the impregnated product is dried at 100°C for 6 hours, calcined at 500°C in a nitrogen atmosphere for 4 hours, and reduced at 470°C in a hydrogen atmosphere for 4 hours to obtain a Ni-C3N4 / HC catalyst, wherein the relative content of Ni is 3wt%, the relative content of C3N4 is 12wt%, and the catalyst is named D-3Ni-12C3N4 / HC.

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

[0153] 0.2g of the D-3Ni-12C3N4 / HC catalyst in the above comparative example 6, 0.2g of HMF and 24g of tetrahydrofuran were added to a stirred autoclave, and 1.5MPa of hydrogen was charged. 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 150°C for 20h, and the HMF conversion rate was calculated by gas phase analysis of the reaction liquid to be >99%, the product DMF selectivity was 76.2%, and the selectivity of the key byproduct 2,5-furan dimethanol was 3.2%.

[0154] 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 catalyst for preparing 2,5-dimethylfuran, characterized in that: The catalyst comprises nickel, C3N4 and a carrier, wherein the carrier is activated carbon HC; the oxygen content of the HC is 4wt% to 18wt%, preferably 6wt% to 15wt%.

2. The catalyst according to claim 1, characterized in that The catalyst has a nickel content of 0.5wt% to 10wt% and a C3N4 content of 2wt% to 30wt% based on the carrier mass; preferably, the nickel content of 1wt% to 6wt% and the C3N4 content of 4wt% to 20wt%.

3. The catalyst according to claim 1, characterized in that The total specific surface area of ​​the catalyst is 700 to 1800 m 2 ·g -1 , preferably 800~1300m 2 ·g -1 .

4. The catalyst according to claim 1, characterized in that The molar ratio of metallic Ni to oxidized NiO in the catalyst is 0.35-0.70:1, preferably 0.40-0.65:

1.

5. The method for preparing the catalyst according to any one of claims 1 to 4, comprising the following steps: The activated carbon is firstly activated under a hydrogen atmosphere at high temperature, and then a nickel source and a nitrogen-containing precursor are loaded on the activated carbon after hydrogen activation, and then dried, calcined and reduced to obtain the catalyst.

6. The preparation method according to claim 5, characterized in that: The nickel source and the nitrogen-containing precursor are first prepared into a solution, and then mixed with the activated carbon activated by hydrogen, and then dried, calcined and reduced to obtain the catalyst.

7. The preparation method according to claim 6, characterized in that: The nickel source is calculated as nickel, the nitrogen-containing precursor is calculated as the sum of the masses of C and N, and the mass ratio of the activated carbon after hydrogen activation to 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.

8. The preparation method according to claim 5, characterized in that: The temperature of hydrogen activation is 500-1200° C., preferably 600-1000° C.; the activation time is 2-12 hours, preferably 3-10 hours; and the activation atmosphere is hydrogen or a hydrogen-argon mixed gas.

9. The preparation method according to claim 5, characterized in that: The calcination temperature is 300-650° C., preferably 350-600° C.; the calcination time is 1-12 hours, preferably 2-6 hours; the calcination atmosphere is a non-oxygen gas atmosphere; preferably, the non-oxygen gas includes at least one of nitrogen and argon.

10. The preparation method according to claim 5, characterized in that: The reduction temperature is 300-700° C., preferably 350-550° C.; the reduction time is 1-12 hours, preferably 2-6 hours; and the reduction atmosphere is hydrogen or a hydrogen-argon mixed gas.

11. The preparation method according to claim 5, characterized in that: The nickel source comprises 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; And / or, the nitrogen-containing precursor includes one or more of urea, cyanoguanidine, and melamine, preferably at least one of urea and cyanoguanidine.

12. The preparation method according to claim 5, characterized in that: The activated carbon includes at least one of coconut shell activated carbon and wood activated carbon, preferably coconut shell activated carbon.

13. The preparation method according to claim 5, characterized in that: The coconut shell activated carbon has an oxygen content of 20 wt% to 40 wt%, preferably 25 wt% to 38 wt%.

14. Use of the catalyst according to any one of claims 1 to 4 or the catalyst prepared by the preparation method according to any one of claims 5 to 13 in the reaction of preparing 2,5-dimethylfuran from 5-hydroxymethylfurfural.

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