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 a Ni-SCM-X molecular sieve, wherein X is 14 or 15; ni comprises metallic Ni and Ni < 2 + >, and the molar ratio of Ni to Ni < 2 + > is 0.02-0.15. The catalyst 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 an application thereof, and in particular to a catalyst for catalytically converting 5-hydroxymethylfurfural to prepare 2,5-dimethylfuran, a preparation method and an application thereof. Background Art

[0002] Due to the increasing consumption of fossil resources and the increasing demand for chemicals and energy in today's society, the preparation of high-value-added chemicals and fuels from renewable biological resources has become one of the research hotspots in the field of new energy. As a sustainable and renewable resource, biomass is abundant, widely distributed, inexpensive and can achieve low-carbon circulation. It can meet the society's demand for fuels and chemicals, thereby realizing the transition from non-renewable petroleum resources to renewable bioenergy. At present, several bio-based PX synthesis pathways have been reported, such as the preparation of PX by pyrolysis or reforming of biomass; the preparation of PX by catalytic conversion of small molecule compounds derived from biomass, including the preparation of PX from biomass ethanol, the preparation of PX from cellulose via isobutanol, or the preparation of PX from 2,5-methylfuran (DMF) from the "sugar platform". Among them, the preparation of PX via 2,5-dimethylfuran is one of the most in-depth and widely studied bio-based synthesis pathways, with the advantages of high selectivity and low separation energy consumption.

[0003] DMF is mainly prepared by 5-hydroxymethylfurfural (HMF) hydrogenolysis, and when using hydrogen as hydrogen source, conventional catalyst comprises the noble metal of load, such as ruthenium (Ru), platinum (Pt) and palladium (Pd), and transition metal, such as nickel (Ni), copper (Cu), cobalt (Co) etc. CN114832833A has reported a kind of Ni3Fe catalyst of load single atom noble metal, and in 60mL THF solvent, dissolving load is the HMF of 0.5wt%, and according to HMF / Pt mol ratio, is that 100 / 1 adds Ni3Fe catalyst.At 160 ℃, 1MPaH2 condition, react after 90 minutes, HMF transforms completely, and DMF productive rate is up to 99.2%. CN108654693B reported that a solid catalytic material was obtained by using a porous metal organic framework as a carrier, introducing a palladium element by an impregnation-reduction method, and then treating it with a polydimethylsiloxane coating. It was used to catalyze the conversion of hexose (especially hexose) into 2,5-dimethylfuran. For example, when fructose was used as a substrate, after reacting at 110°C for 2.5 hours, fructose was completely converted, and 2,5-dimethylfuran was as high as 93%. In the presence of noble metal catalysts, HMF can usually produce DMF with satisfactory results, but the low reusability and high cost of noble metals seriously hinder their commercial application. CN106279075B reported that a heterogeneous iron-based catalyst was used to catalyze the preparation of DMF from HMF. After reacting for 12 hours at 240°C and 1MPa H2, the HMF conversion rate was 73% and the DMF yield was 32.5%. The catalytic efficiency of the iron-based catalyst needs to be further improved.

[0004] In summary, the existing technologies mainly have the problems of high production cost and low catalytic efficiency of catalysts, which bring great problems to practical industrial applications. Summary of the invention

[0005] The technical problem to be solved by the present invention is the high production cost and low catalytic efficiency of the catalyst in the prior art. A catalyst for catalytic conversion of 5-hydroxymethylfurfural (HMF) to prepare 2,5-dimethylfuran and its preparation method and application are provided. The catalyst is used in the reaction of preparing 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 recycling.

[0006] The first aspect of the present invention provides a catalyst for preparing 2,5-dimethylfuran, the catalyst comprising Ni-SCM-X molecular sieve, X is 14 or 15; Ni comprises metallic Ni and Ni 2+ , where Ni / Ni 2+ The molar ratio is 0.02 to 0.15, preferably 0.05 to 0.12.

[0007] Furthermore, the average size of nickel particles in the catalyst is 2.0 to 6.0 nm, preferably 3.0 to 5.0 nm.

[0008] Furthermore, in the catalyst, based on the mass of the SCM-X molecular sieve, the content of Ni as Ni is 0.2wt% to 5.0wt%, preferably 0.5wt% to 3.0wt%.

[0009] Further, the SCM-X molecular sieve, wherein X is 14 or 15. The SCM-14 molecular sieve and its preparation method are described in patent CN109081360A, and the entire contents of the patent are fully incorporated herein by reference. The SCM-15 molecular sieve and its preparation method are described in patent CN109081359A, and the entire contents of the patent are fully incorporated herein by reference.

[0010] Furthermore, the Si / Ge molar ratio of the SCM-X molecular sieve is 1.5-8, preferably 2-7.

[0011] Furthermore, the total specific surface area of ​​the catalyst is 90 to 370 m 2 ·g -1 , preferably 100 to 350 m 2 ·g -1 .

[0012] Furthermore, the total acid content of the catalyst is 130 to 220 μmol·g -1 , preferably 150 to 200 μmol·g -1 .

[0013] Furthermore, the catalyst The acid / Lewis acid ratio is 0.3 to 0.8, preferably 0.4 to 0.6.

[0014] The second aspect of the present invention provides a method for preparing the above catalyst, comprising:

[0015] The SCM-X molecular sieve is mixed with a nickel-containing precursor, and the obtained product is dried, calcined and reduced to obtain a Ni-SCM-X molecular sieve.

[0016] Furthermore, the nickel-containing precursor is selected from at least one of nickelocene (bis(cyclopentadiene)nickel), bis-(1,5-cyclooctadiene)nickel, bis(tetramethylcyclopentadienyl)nickel, 1,2-bis(diphenylphosphine)ethane nickel chloride and bis(triphenylphosphine)nickel chloride, preferably nickelocene.

[0017] Furthermore, the mass ratio of Ni (theoretical amount of Ni in the organometallic precursor) to SCM-X molecular sieve is 0.2-8.0:100, preferably 0.5-5.0:100.

[0018] Furthermore, the mixing is physical mixing, and the mixing methods include grinding, ball milling, etc.

[0019] Furthermore, the drying conditions are: drying at 50-130° C. for 2-8 hours.

[0020] Furthermore, the calcination conditions are: calcination at 300-650° C. for 1-12 hours, and the calcination atmosphere is oxygen or air.

[0021] Furthermore, the reduction is preferably carried out under a hydrogen atmosphere, the reduction temperature is 300 to 500° C., preferably 350 to 450° C., and the reduction time is 1 to 8 hours, preferably 2 to 6 hours.

[0022] The third aspect of the present invention provides a method for preparing 2,5-dimethylfuran, comprising:

[0023] Under the action of the above catalyst, 5-hydroxymethylfurfural is mixed with an organic solvent and then hydrogenated in one step to obtain 2,5-dimethylfuran.

[0024] Furthermore, the reaction conditions include: reaction temperature of 130-220° C., preferably 150-200° C.; reaction time of 1-12 h, preferably 2-10 h; hydrogen pressure of 0.5-4 MPa, preferably 1-3 MPa.

[0025] Furthermore, the organic solvent comprises at least one of tetrahydrofuran, n-butanol, γ-valerolactone, methyl isobutyl ketone and acetone, preferably tetrahydrofuran.

[0026] Furthermore, the mass ratio of the substrate 5-hydroxymethylfurfural to the catalyst is 0.2-5:1, preferably 0.5-4:1.

[0027] Furthermore, the mass ratio of the organic solvent to the substrate 5-hydroxymethylfurfural is 40-400:1, preferably 50-300:1.

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

[0029] In the present invention, the catalyst includes Ni-SCM-X, X is 14 or 15, Ni is evenly distributed and has a small particle size, and the metallic Ni and Ni in the molecular sieve are 2+ The molar ratio of 5-hydroxymethylfurfural to 2,5-dimethylfuran is suitable, and it is used to catalyze the conversion of 5-hydroxymethylfurfural to prepare 2,5-dimethylfuran. It has the characteristics of efficient conversion of 5-hydroxymethylfurfural under mild reaction conditions and high selectivity for the product 2,5-dimethylfuran, as well as outstanding stability in catalyst recycling.

[0030] In the present invention, the Ni-Ni-SCM-X molecular sieve is prepared by mixing the SCM-X molecular sieve with a nickel source containing an organic ligand, and drying, calcining and reducing the obtained product. The organic ligand has a large size and a strong interaction with nickel, so that the nickel is evenly distributed and the nickel particles are uniform and small in size. At the same time, the reaction conditions are controlled so that the metallic Ni and Ni 2+ The molar ratio is appropriate, and under mild reaction conditions, 5-hydroxymethylfurfural can be efficiently converted into 2,5-dimethylfuran, and the substrate conversion rate and product selectivity are significantly improved. In addition, the prepared Ni-SCM-X molecular sieve has good stability and no significant changes were observed after four cycles. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the XRD pattern of the Ni-SCM-14 catalyst in Example 1;

[0032] Figure 2 NH3-TPD diagram of Ni-SCM-14 catalyst in Example 1;

[0033] Figure 3 is the pyridine infrared image of the Ni-SCM-14 catalyst in Example 1;

[0034] Figure 4 is the XPS graph of the Ni-SCM-14 catalyst in Example 1;

[0035] Figure 5 TEM image of the Ni-SCM-14 catalyst in Example 1;

[0036] Figure 6 is the XRD pattern of the Ni-SCM-15 catalyst in Example 4;

[0037] Figure 7 This is the TEM image of the Ni / SCM-14 catalyst in Comparative Example 1. DETAILED DESCRIPTION

[0038] 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, INNOWAX gas chromatography capillary column (60m, 0.32mm), the gas chromatograph is Agilent 7890B, and the detector is a hydrogen flame ionization detector (FID), INNOWAX gas chromatography capillary column (60m, 0.32mm).

[0039] 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.

[0040] 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.

[0041] In the present invention, the NH3 temperature-programmed desorption (NH3-TPD) experiment is carried out on a TPD / TPR Altamira AMI-3300 instrument, and the total acid content is calculated by fitting and peak separation of the obtained spectrum.

[0042] The pyridine adsorption infrared method (Nicolet Model 710 spectrometer) was used to determine the amount and type of acid in the catalyst. The specific operating steps are as follows: a. Sample pretreatment: The sample (about 30 mg) was pressed into a thin disc with a diameter of 13 mm and loaded into the infrared sample tank; then, the sample was pretreated under vacuum cell conditions at 400°C for 1 hour. After the sample tank was cooled to room temperature, the sample infrared data was scanned as the background. b. Pyridine adsorption: At room temperature and vacuum environment, pyridine vapor was introduced into the original position until the adsorption reached equilibrium, and the adsorption time was 1 hour. c. Pyridine desorption. After the adsorption was completed, the vacuum was evacuated at 100°C until the internal pressure no longer changed. The desorption time was 40 minutes, and the infrared absorption spectrum was scanned and recorded respectively. The difference spectrum before and after pyridine adsorption is the obtained pyridine adsorption-infrared absorption spectrum. The acid content of the sample was semi-quantitatively calculated based on the spectrum:

[0043]

[0044] Where r and w are the diameter (cm) and mass (g) of the catalyst disc, A is the absorbance integral value at the specified wave number peak based on the scanning pyridine adsorption-infrared absorption spectrum, IMEC is the integrated molar extinction coefficient, IMECL is 2.22, and IMECB is 1.67.

[0045] In the present invention, the transmission electron microscope (TEM) model of the molecular sieve is S-4800II field emission scanning electron microscope. The size of the nickel particles in the molecular sieve is obtained by selecting the size of about 30 nickel particles for statistics through the TEM image and then calculating the average value.

[0046] 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.

[0047] In the present invention, N2 adsorption-desorption (BET) is performed using a NOVA1200e 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.

[0048] In the present invention, the 5-hydroxymethylfurfural conversion formula is:

[0049] HMF conversion rate % = (molar amount of HMF participating in the reaction) / (molar amount of HMF as the reaction substrate) × 100%.

[0050] In the present invention, the product DMF yield calculation formula is:

[0051] The yield of product DMF (%) = (molar amount of DMF generated by the reaction) / (molar amount of reaction substrate HMF) × 100%.

[0052] In the present invention, the product DMF selectivity calculation formula is:

[0053] 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%.

[0054] In the present invention, the by-product 5-methylfurfural selectivity calculation formula is:

[0055] Selectivity of 5-methylfurfural %=(molar amount of 5-methylfurfural produced by the reaction) / (molar amount of HMF participating in the reaction)×100%.

[0056] 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.

[0057] Example 1

[0058] The SCM-14 molecular sieve was synthesized according to the preparation method in Example 1 described in CN109081360A, wherein the Si / Ge molar ratio was 3.7. The nickel precursor was nickelocene, and the mass ratio of Ni (theoretical amount of Ni in the organometallic precursor) to the above-mentioned SCM-14 molecular sieve was 1.0:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 100°C for 4 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions, the reduction temperature was 400°C, and the reduction time was 3 hours. Ni-SCM-14 molecular sieve was obtained.

[0059] The Si / Ge molar ratio of the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) to be 3.7, and the relative content of Ni was 1.0 wt%. The specific surface area of ​​the sample was calculated by BET method to be 138 m 2 / g. The XRD of the sample is as follows Figure 1 The NH3-TPD of the sample is shown as Figure 2 As shown, the total acid content calculated is 175 μmol·g- 1 The pyridine infrared image of the sample is as follows Figure 3 As shown, the calculated / Lewis acid ratio is 0.50. The XPS of the sample is as follows Figure 4 As shown, the binding energy at 852.0 eV corresponds to the metal element Ni (2p 3 / 2 The peak with a binding energy of 855.6 eV corresponds to divalent nickel (2 + ), metallic Ni and Ni 2+ The molar ratio of Ni / Ni 2+ The TEM of the sample is as follows Figure 5 As shown, it can be seen that the nickel is evenly distributed without obvious aggregation, and the average particle size of the nickel particles is 3.5 nm.

[0060] Example 2

[0061] The SCM-14 molecular sieve was synthesized according to the preparation method in Example 1 described in CN109081360A, wherein the Si / Ge molar ratio was 3.7. The nickel precursor was nickelocene, and the mass ratio of Ni (theoretical amount of Ni in the organometallic precursor) to the above-mentioned SCM-14 molecular sieve was 2.0:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 80°C for 4 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions, the reduction temperature was 380°C, and the reduction time was 4 hours. Ni-SCM-14 molecular sieve was obtained.

[0062] The Si / Ge molar ratio of the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) to be 3.7, and the relative content of Ni was 2.0 wt%. The specific surface area of ​​the sample was calculated by the BET method to be 135 m 2 / g. XRD and Figure 1 The NH3-TPD of the sample is similar to Figure 2 Similarly, the total acid content calculated is 183 μmol·g- 1 The pyridine infrared image of the sample is as follows Figure 3 Similarly, the calculation / Lewis acid ratio is 0.57. XPS and Figure 4 Similarly, the binding energy at 852.0 eV corresponds to the metal element Ni (2p 3 / 2 The peak with a binding energy of 855.6 eV corresponds to divalent nickel (2 + ), metallic Ni and Ni 2+ The molar ratio of Ni / Ni 2+ The ratio is 0.09. Figure 5 Similarly, it can be seen that the nickel is evenly distributed without obvious aggregation, and the average particle size of the nickel particles is 3.3 nm.

[0063] Example 3

[0064] The SCM-14 molecular sieve was synthesized according to the preparation method in Example 2 described in CN109081360A, wherein the Si / Ge molar ratio was 3.5. The nickel precursor was nickelocene, and the mass ratio of Ni (theoretical amount of Ni in the organometallic precursor) to the above-mentioned SCM-14 molecular sieve was 1.5:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 90°C for 4 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions, the reduction temperature was 410°C, and the reduction time was 3 hours. Ni-SCM-14 molecular sieve was obtained.

[0065] The Si / Ge molar ratio of the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) to be 3.5, and the relative content of Ni was 1.5 wt%. The specific surface area of ​​the sample was calculated by the BET method to be 131 m 2 / g. XRD and Figure 1 The NH3-TPD of the sample is similar to Figure 2 Similarly, the total acid content calculated is 172 μmol·g- 1 The pyridine infrared image of the sample is as follows Figure 3 Similarly, the calculation / Lewis acid ratio is 0.52. XPS and Figure 4Similarly, the binding energy at 852.0 eV corresponds to the metal element Ni (2p 3 / 2 The peak with a binding energy of 855.6 eV corresponds to divalent nickel (2 + ), metallic Ni and Ni 2+ The molar ratio of Ni / NiO was calculated by the ratio of the two peak areas to be 0.07. Figure 5 Similarly, it can be seen that the nickel is evenly distributed without obvious aggregation, and the average particle size of the nickel particles is 3.7 nm.

[0066] Example 4

[0067] The SCM-15 molecular sieve was synthesized according to the preparation method in Example 1 described in CN109081359A, wherein the Si / Ge molar ratio was 5.1. The nickel precursor was nickelocene, and the mass ratio of Ni (theoretical amount of Ni in the organometallic precursor) to the above-mentioned SCM-15 molecular sieve was 1.0:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 80°C for 5 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions at a reduction temperature of 400°C and a reduction time of 2 hours. Ni-SCM-15 molecular sieve was obtained.

[0068] The Si / Ge molar ratio of the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) to be 5.1, and the relative content of Ni was 1.2 wt%. The specific surface area of ​​the sample was calculated by the BET method to be 325 m 2 / g. The XRD of the sample is as follows Figure 6 As shown. The NH3-TPD of the sample Figure 2 Similarly, the total acid content calculated is 157 μmol·g- 1 The pyridine infrared image of the sample is as follows Figure 3 Similarly, the calculation / Lewis acid ratio is 0.46. XPS and Figure 4 Similarly, the binding energy at 852.0 eV corresponds to the metal element Ni (2p 3 / 2 The peak with a binding energy of 855.6 eV corresponds to divalent nickel (2 + ), metallic Ni and Ni 2+ The molar ratio of Ni / Ni 2+ The ratio is 0.10. Figure 5 Similarly, it can be seen that the nickel is evenly distributed without obvious aggregation, and the average particle size of the nickel particles is 4.1 nm.

[0069] Example 5

[0070] The SCM-14 molecular sieve was synthesized according to the preparation method in Example 1 described in CN109081360A, wherein the Si / Ge molar ratio was 3.7. The nickel precursor was bis-(1,5-cyclooctadiene) nickel, and the mass ratio of Ni (theoretical amount of Ni in the organometallic precursor) to the above-mentioned SCM-14 molecular sieve was 0.9:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 100°C for 4 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions, the reduction temperature was 400°C, and the reduction time was 3 hours. Ni-SCM-14 molecular sieve was obtained.

[0071] The Si / Ge molar ratio of the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) to be 3.7, and the relative content of Ni was 0.9 wt%. The specific surface area of ​​the sample was calculated by the BET method to be 136 m 2 / g. XRD and Figure 1 The NH3-TPD of the sample is similar to Figure 2 Similarly, the total acid content calculated is 143 μmol·g- 1 The pyridine infrared spectrum of the sample is Figure 3 Similarly, the calculation / Lewis acid ratio is 0.47. XPS and Figure 4 Similarly, the binding energy at 852.0 eV corresponds to the metal element Ni (2p 3 / 2 The peak with a binding energy of 855.6 eV corresponds to divalent nickel (2 + ), metallic Ni and Ni 2+ The molar ratio of Ni / Ni 2+ The ratio is 0.13. Figure 5 Similarly, the average particle size of nickel particles is 5.5 nm.

[0072] Example 6

[0073] The SCM-14 molecular sieve was synthesized according to the preparation method in Example 2 described in CN109081360A, wherein the Si / Ge molar ratio was 3.5. The nickel precursor was di(tetramethylcyclopentadienyl)nickel, and the mass ratio of Ni (theoretical amount of Ni in the organometallic precursor) to the above-mentioned SCM-14 molecular sieve was 1.3:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 100°C for 4 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions, the reduction temperature was 400°C, and the reduction time was 3 hours. Ni-SCM-14 molecular sieve was obtained.

[0074] The Si / Ge molar ratio of the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) to be 3.5, and the relative content of Ni was 1.3 wt%. The specific surface area of ​​the sample was calculated by the BET method to be 142 m 2 / g. XRD and Figure 1 The NH3-TPD of the sample is similar to Figure 2 Similarly, the total acid content calculated is 161 μmol·g- 1 The pyridine infrared spectrum of the sample is Figure 3 Similarly, the calculation / Lewis acid ratio is 0.36. XPS and Figure 4 Similarly, the binding energy at 852.0 eV corresponds to the metal element Ni (2p 3 / 2 The peak with a binding energy of 855.6 eV corresponds to divalent nickel (2 + ), metallic Ni and Ni 2+ The molar ratio of Ni / Ni 2+ The ratio is 0.11. Figure 5 Similarly, the average particle size of nickel particles is 5.8 nm.

[0075] Examples 7-12

[0076] Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 100, the mass ratio of HMF to catalyst was 1, the hydrogen pressure was 1.5 MPa, the reaction temperature was 190° C., and the reaction time was 3 h.

[0077] 0.2 g of the catalyst in the above-mentioned Examples 1-6, 0.2 g of HMF and 20 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 190° C. for 3 h, and the HMF conversion rate and the selectivity of the product DMF and the key byproduct 5-methylfurfural 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 1-6

[0079]

[0080] Embodiment 13

[0081] Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 80, the mass ratio of HMF to catalyst was 2, the hydrogen pressure was 2.5 MPa, the reaction temperature was 190° C., and the reaction time was 3 h.

[0082] 0.2g of the Ni-SCM-14 catalyst in Example 1, 0.4g of HMF and 32g of tetrahydrofuran were added to a stirred autoclave, and 2.5MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using magnetic stirring. The reaction was carried out at 190°C for 3h, and the HMF conversion rate was calculated by gas phase analysis of the reaction liquid to be >99%, the product DMF selectivity was 87.5%, and the selectivity of the key byproduct 5-methylfurfural was 0.3%.

[0083] Embodiment 14

[0084] Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 80, the mass ratio of HMF to catalyst was 0.8, the hydrogen pressure was 1 MPa, the reaction temperature was 190° C., and the reaction time was 2 h.

[0085] 0.2g of the Ni-SCM-14 catalyst in Example 1, 0.16g of HMF and 12.8g of tetrahydrofuran were added to a stirred autoclave, and 1MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using magnetic stirring. The reaction was carried out at 190°C for 2h, and the HMF conversion rate was calculated by gas phase analysis of the reaction liquid to be >99%, the product DMF selectivity was 89.1%, and the selectivity of the key byproduct 5-methylfurfural was 0.1%.

[0086] Embodiment 15

[0087] Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 120, the mass ratio of HMF to catalyst was 1.6, the hydrogen pressure was 1.3 MPa, the reaction temperature was 200° C., and the reaction time was 5 h.

[0088] 0.2g of the Ni-SCM-14 catalyst in Example 1, 0.32g of HMF and 38.4g of tetrahydrofuran were added to a stirred autoclave, and 1.3MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using magnetic stirring. The reaction was carried out at 200°C for 5h, and the HMF conversion rate was calculated to be >99% by gas phase analysis of the reaction liquid, the product DMF selectivity was 88.4%, and the selectivity of the key byproduct 5-methylfurfural was 0.2%.

[0089] Example 16

[0090] Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 120, the mass ratio of HMF to catalyst was 0.9, the hydrogen pressure was 2 MPa, the reaction temperature was 180° C., and the reaction time was 4 h.

[0091] 0.2g of the Ni-SCM-14 catalyst in Example 1, 0.18g of HMF and 36g 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 magnetic stirring. The reaction was carried out at 180°C for 4h, and the HMF conversion rate was calculated by gas phase analysis of the reaction liquid to be >99%, the product DMF selectivity was 88.2%, and the selectivity of the key byproduct 5-methylfurfural was 0.3%.

[0092] Embodiment 17

[0093] Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 150, the mass ratio of HMF to catalyst was 1.3, the hydrogen pressure was 1.5 MPa, the reaction temperature was 180° C., and the reaction time was 3 h.

[0094] 0.2g of the Ni-SCM-14 catalyst in Example 1, 0.26g of HMF and 39g 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 magnetic stirring. The reaction was carried out at 180°C for 3h, and the HMF conversion rate was calculated by gas phase analysis of the reaction liquid to be >99%, the product DMF selectivity was 88.1%, and the selectivity of the key byproduct 5-methylfurfural was 0.2%.

[0095] Embodiment 18

[0096] Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 150, the mass ratio of HMF to catalyst was 0.6, the hydrogen pressure was 1 MPa, the reaction temperature was 180° C., and the reaction time was 3 h.

[0097] 0.2g of the Ni-SCM-14 catalyst in Example 1, 0.12g of HMF and 18g of tetrahydrofuran were added to a stirred autoclave, and 1MPa 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 180°C for 3h, and the HMF conversion rate was calculated by gas phase analysis of the reaction liquid to be >99%, the product DMF selectivity was 89.2%, and the selectivity of the key byproduct 5-methylfurfural was 0.3%.

[0098] Embodiment 19

[0099] Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 100, the mass ratio of HMF to catalyst was 0.8, the hydrogen pressure was 1 MPa, the reaction temperature was 180° C., and the reaction time was 4 h.

[0100] 0.2g of the Ni-SCM-14 catalyst in Example 1, 0.16g of HMF and 16g of tetrahydrofuran were added to a stirred autoclave, and 1MPa of hydrogen was added. The temperature was raised to a preset temperature using a programmed heating jacket, and then stirred using magnetic stirring. The reaction was carried out at 180°C for 4h, and the HMF conversion rate was calculated by gas phase analysis of the reaction liquid to be >99%, the product DMF selectivity was 89.3%, and the selectivity of the key byproduct 5-methylfurfural was 0.2%.

[0101] Embodiment 20

[0102] Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 100, the mass ratio of HMF to catalyst was 1.5, the hydrogen pressure was 2 MPa, the reaction temperature was 180° C., and the reaction time was 6 h.

[0103] 0.2g of the Ni-SCM-14 catalyst in Example 1, 0.3g of HMF and 30g 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 magnetic stirring. The reaction was carried out at 180°C for 6h, and the HMF conversion rate was calculated by gas phase analysis of the reaction liquid to be >99%, the product DMF selectivity was 88.7%, and the selectivity of the key byproduct 5-methylfurfural was 0.3%.

[0104] In order to more intuitively describe the reaction conditions and results of the above Examples 13-20, various parameters and results are listed in Table 2.

[0105] Table 2 Catalytic performance results of Examples 13-20

[0106]

[0107] Embodiment 21

[0108] Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 100, the mass ratio of HMF to catalyst was 1, the hydrogen pressure was 1.5 MPa, the reaction temperature was 190° C., and the reaction time was 3 h.

[0109] 0.2g of the catalyst in Example 1, 0.2g of HMF and 20g of tetrahydrofuran were added to a stirred autoclave, and 1.5MPa of hydrogen was filled. The heating jacket was heated to a preset temperature using a programmed temperature increase, and then stirred using a magnetic stirrer. The reaction was carried out at 190°C for 3h, and the HMF conversion rate and the product DMF and the selectivity of the key byproduct 2-methylfurfural were 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, and the results are shown in Table 3. The results show that after 4 reactions, the HMF conversion rate remained above 99%, the DMF selectivity remained at 88.7%, and the selectivity of the key byproduct 5-methylfurfural was not higher than 0.3%, indicating that the Ni-SCM-14 catalyst has good cyclic stability.

[0110] Table 3 Catalyst recycling data

[0111]

[0112]

[0113] Comparative Example 1

[0114] The SCM-14 molecular sieve was synthesized according to the preparation method in Example 1 described in CN109081360A, wherein the Si / Ge molar ratio was 3.7. The precursor of nickel was nickel nitrate, and the mass ratio of Ni (theoretical amount of Ni in nickel nitrate) to the above-mentioned SCM-14 molecular sieve was 1.0:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 100°C for 4 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions, the reduction temperature was 400°C, and the reduction time was 3 hours. Ni / SCM-14 molecular sieve was obtained.

[0115] The Si / Ge molar ratio of the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) to be 3.7, and the relative content of Ni was 1.0 wt%. The specific surface area of ​​the sample was calculated by BET method to be 148 m 2 / g. The total acid content calculated based on the NH3-TPD of the sample is 173μmol·g- 1 Calculated based on the pyridine infrared image of the sample / Lewis acid ratio is 0.74. According to XPS calculation of the sample (Ni / Ni 2+ The ratio is 0.41. Figure 7 As shown, it can be seen that the distribution of nickel is uneven and the average particle size of nickel particles is 12.6 nm.

[0116] Tetrahydrofuran is used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF is 100, the mass ratio of HMF to catalyst is 1, the hydrogen pressure is 1.5MPa, the reaction temperature is 190°C, and the reaction time is 3h. 0.2g of the catalyst in the above-mentioned comparative example 1, 0.2g of HMF and 20g of tetrahydrofuran are added to a stirred autoclave, and 1.5MPa of hydrogen is filled. The programmed temperature heating jacket is raised to a preset temperature, and magnetic stirring is used and then stirred. The reaction is carried out at 190°C for 3h, and the HMF conversion rate is calculated by gas phase analysis of the reaction liquid>99%, the product DMF selectivity is 25.9%, and the selectivity of the key byproduct 5-methylfurfural is 2.7%.

[0117] Comparative Example 2

[0118] SCM-14 molecular sieve was synthesized by the preparation method in Example 1 described in CN109081360A, wherein the Si / Ge molar ratio was 3.7. Tetrahydrofuran was used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF was 100, the mass ratio of HMF to catalyst was 1, the hydrogen pressure was 1.5MPa, the reaction temperature was 190°C, and the reaction time was 3h. 0.2g of the SCM-14 molecular sieve catalyst, 0.2g of HMF and 20g of tetrahydrofuran in the above-mentioned comparative example 2 were added to a stirred autoclave, and 1.5MPa of hydrogen was filled. The heating jacket was heated to a preset temperature using a programmed temperature increase, and then stirred using magnetic stirring. The reaction was carried out at 190°C for 3h, and the HMF conversion rate was calculated by gas phase analysis of the reaction liquid to be 7%, and no product DMF or key byproduct 5-methylfurfural was detected.

[0119] Comparative Example 3

[0120] The SCM-14 molecular sieve was synthesized according to the preparation method in Example 1 described in CN109081360A, wherein the Si / Ge molar ratio was 3.7. The nickel precursor was nickel levulinate, and the mass ratio of Ni (theoretical amount of Ni in nickel nitrate) to the above-mentioned SCM-14 molecular sieve was 1.0:100. The mixture was fully ground in a mortar to obtain a uniformly dispersed mixture. The above-mentioned product was dried in an oven at 100°C for 4 hours, then calcined at 550°C for 4 hours, and reduced under hydrogen conditions, the reduction temperature was 400°C, and the reduction time was 3 hours. Ni / SCM-14 molecular sieve was obtained.

[0121] The Si / Ge molar ratio of the sample was measured by inductively coupled plasma atomic emission spectroscopy (ICP) to be 3.7, and the relative content of Ni was 1.0 wt%. The specific surface area of ​​the sample was calculated by the BET method to be 137 m 2 / g. The total acid content calculated based on the NH3-TPD of the sample is 161μmol·g -1 Calculated based on the pyridine infrared image of the sample / Lewis acid ratio is 0.82. According to XPS calculation of the sample (Ni / Ni 2+ The ratio is 0.35. According to the TEM results of the sample, the average particle size of the nickel particles is 10.3nm.

[0122] Tetrahydrofuran is used as the reaction solvent, the mass ratio of tetrahydrofuran to HMF is 100, the mass ratio of HMF to catalyst is 1, the hydrogen pressure is 1.5MPa, the reaction temperature is 190°C, and the reaction time is 3h. 0.2g of the catalyst in the above-mentioned comparative example 3, 0.2g of HMF and 20g of tetrahydrofuran are added to a stirred autoclave, and 1.5MPa of hydrogen is filled. The programmed temperature heating jacket is raised to a preset temperature, and magnetic stirring is used and then stirred. The reaction is carried out at 190°C for 3h, and the HMF conversion rate is calculated by gas phase analysis of the reaction liquid>99%, the product DMF selectivity is 37.2%, and the selectivity of the key byproduct 5-methylfurfural is 3.3%.

[0123] 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 Ni-SCM-X molecular sieve, X is 14 or 15; Ni comprises metallic Ni and Ni 2+ , where Ni / Ni 2+ The molar ratio is 0.02 to 0.15, preferably 0.05 to 0.

12.

2. The catalyst according to claim 1, characterized in that The average size of nickel particles in the catalyst is 2.0 to 6.0 nm, preferably 3.0 to 5.0 nm.

3. The catalyst according to claim 1, characterized in that In the catalyst, based on the mass of the SCM-X molecular sieve, the content of Ni as Ni is 0.2wt% to 5.0wt%, preferably 0.5wt% to 3.0wt%.

4. The catalyst according to claim 1, characterized in that In the SCM-X molecular sieve, the Si / Ge molar ratio is 1.5-8, preferably 2-7.

5. The catalyst according to claim 1, characterized in that The total specific surface area of ​​the catalyst is 90 to 370 m 2 ·g -1 , preferably 100 to 350 m 2 ·g -1 and / or, The total acid content of the catalyst is 130 to 220 μmol·g -1 , preferably 150 to 200 μmol·g -1 and / or, The catalyst The acid / Lewis acid ratio is 0.3 to 0.8, preferably 0.4 to 0.

6.

6. A method for preparing the catalyst according to any one of claims 1 to 5, comprising: The SCM-X molecular sieve is mixed with a nickel-containing precursor, and the obtained product is dried, calcined and reduced to obtain a Ni-SCM-X molecular sieve.

7. The method according to claim 6, characterized in that The nickel-containing precursor is selected from at least one of nickelocene (bis(cyclopentadiene)nickel), bis-(1,5-cyclooctadiene)nickel, bis(tetramethylcyclopentadienyl)nickel, 1,2-bis(diphenylphosphine)ethane nickel chloride and bis(triphenylphosphine)nickel chloride, preferably nickelocene.

8. The method according to claim 6, characterized in that The mass ratio of Ni to SCM-X molecular sieve is 0.2-8.0:100, preferably 0.5-5.0:

100.

9. The method according to claim 6, characterized in that The calcination conditions are: calcination at 300-650°C for 1-12 hours, and the calcination atmosphere is an oxygen-containing gas; And / or, the reduction is preferably carried out under a hydrogen atmosphere, the reduction temperature is 300 to 500° C., preferably 350 to 450° C., and the reduction time is 1 to 8 hours, preferably 2 to 6 hours.

10. A method for preparing 2,5-dimethylfuran, comprising: Under the action of any one of the catalysts described in claims 1 to 5, 5-hydroxymethylfurfural is mixed with an organic solvent and then subjected to one-step hydrogenolysis to obtain 2,5-dimethylfuran.

11. The method according to claim 10, characterized in that The organic solvent comprises at least one of tetrahydrofuran, n-butanol, γ-valerolactone, methyl isobutyl ketone and acetone, preferably tetrahydrofuran.

12. The method according to claim 10, characterized in that The reaction temperature is 130-220°C, preferably 150-200°C; the reaction time is 1-12h, preferably 2-10h; the hydrogen pressure is 0.5-4MPa, preferably 1-3MPa; and / or, the mass ratio of 5-hydroxymethylfurfural to the catalyst is 0.2-5:1, preferably 0.5-4:1; And / or, the mass ratio of the organic solvent to 5-hydroxymethylfurfural is 40-400:1, preferably 50-300:1.

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