Bimetallic site co-w-nc catalysts, methods of making and using same, and methods of making diols from polyols

Abstract

The application relates to the field of catalytic chemistry, and discloses a bimetal site CoW-NC catalyst as well as a preparation method and application thereof and a method for preparing diols from polyhydroxy compounds. The bimetal site CoW-NC catalyst is a material formed by self-assembly of Co and W and nitrogen-doped porous carbon NC, and in the catalyst, the Co is in a reduced state. The metal active component of the catalyst is not easy to be lost, and in the presence of the catalyst, diols can be prepared from polyhydroxy compounds in one-pot, excellent comprehensive effects of raw material conversion rate and diol yield can be obtained, and the catalyst can be recycled for multiple times.

Description

Technical Field

[0001] This invention relates to the field of catalytic chemistry, specifically to a bimetallic site CoW-NC catalyst, its preparation method and application, and a method for producing diols from polyhydroxy compounds. Background Technology

[0002] Biomass-based chemicals can effectively avoid the drawbacks of traditional oil and gas routes, such as dependence on fossil fuels, high energy consumption, and high carbon dioxide emissions. Furthermore, polyhydroxy biomass is widely distributed in nature, making it abundant and readily available. The catalytic production of ethylene glycol from polyhydroxy biomass offers advantages such as: 1. good atom economy; 2. readily available raw materials; 3. renewable resources; and 4. low carbon dioxide emissions. Currently, the technology for catalytic production of diols from polyhydroxy biomass is not yet mature. Therefore, developing new catalysts and processes can advance the industrialization of this technology, thereby generating significant environmental and economic benefits.

[0003] CN105523890A directly uses glucose as a raw material to prepare diols through hydrolysis and hydrogenation in the presence of tungstate and alloy hydrogenation catalysts. This method requires an alloy as a co-catalyst, resulting in a large amount of metal used. Furthermore, tungstate must be added to the reaction system as a co-catalyst, and it is lost with the solvent, leading to poor catalyst recyclability.

[0004] CN102190562A, CN101735014A, and CN102731258A primarily use WC2 and Ni nanoparticles as catalytically active components to convert glucose into ethylene glycol. However, the catalysts used in these technologies suffer from poor recyclability, which poses a significant challenge for practical industrial applications. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of poor catalyst cycle stability in the prior art and to provide a new bimetallic site CoW-NC catalyst. When this catalyst is used in catalytic reactions, such as the production of diols from polyhydroxy biomass, it not only has good catalytic performance but also yields a high yield of diols and has good cycle stability.

[0006] To achieve the above objectives, the first aspect of the present invention provides a novel bimetallic site CoW-NC catalyst, which is a material formed by the self-assembly of Co and W with nitrogen-doped porous carbon NC, wherein Co is in a reduced state in the catalyst.

[0007] The second aspect of the present invention provides a method for preparing the bimetallic site CoW-NC catalyst of the present invention, the method comprising: carbonizing and reducing a metal-organic framework material containing W and Co bimetals to obtain the bimetallic site CoW-NC catalyst; wherein the carbonization and reduction conditions include: a carbonization temperature greater than 150°C.

[0008] A third aspect of the present invention provides the application of the catalyst described herein in the catalytic hydrogenolysis of polyhydroxy compounds.

[0009] A fourth aspect of the present invention provides a method for preparing diols from polyhydroxy compounds, the method comprising: catalytic hydrogenolysis of the polyhydroxy compound in the presence of hydrogen, water and the catalyst described in the present invention.

[0010] Through the above technical solution, the active metal component of the catalyst provided by the present invention is not easily lost. In the presence of the catalyst of the present invention, the one-pot preparation of diols from polyhydroxy compounds can achieve excellent combined effects of raw material conversion rate and diol yield. The catalyst can also be recycled multiple times. Attached Figure Description

[0011] Figure 1 This is an SEM image of the catalyst in Example 1;

[0012] Figure 2 These are the XRD patterns of the catalysts in Example 1 and Comparative Example 2;

[0013] Figure 3 Example 1 is the XPS spectrum of the catalyst in Example 1. Detailed Implementation

[0014] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0015] The first aspect of the present invention provides a novel bimetallic site CoW-NC catalyst, which is a material formed by the self-assembly of Co and W with nitrogen-doped porous carbon NC.

[0016] In this invention, nitrogen-containing metal-organic frameworks (MOFs) are precursors to nitrogen-doped porous carbon (NC); CoW-NC refers to a periodic three-dimensional porous crystalline material formed by the self-assembly of Co and W with nitrogen-doped porous carbon (NC), i.e., a material formed after carbonization derivatization; the CoW-NC catalyst has the advantages of low loss rate of active components and excellent cycle stability; wherein, Co and W can exist in elemental form or in compound form (e.g., oxides), preferably, Co is in a reduced state (i.e., Co exists in elemental form). The catalyst under the aforementioned preferred embodiments is more conducive to improving the catalytic performance of the catalyst.

[0017] According to the present invention, in some embodiments, the chemical valence state of W in the catalyst is +6. The catalysts in the aforementioned embodiments have superior catalytic performance, and when used for the catalytic hydrogenolysis of polyhydroxy compounds, they can achieve a better overall effect in terms of feedstock conversion and diol selectivity.

[0018] In this invention, the valence state of the metal elements in the catalyst is characterized by X-ray photoelectron spectroscopy.

[0019] According to the present invention, in some embodiments, the particle size of the catalyst is 30-1000 nm, for example, 30 nm, 40 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 700 nm, 1000 nm, or any combination of two of the above values, preferably 30-200 nm. The catalysts in the aforementioned embodiments have good uniformity, which can greatly improve the catalytic activity and catalytic stability of the catalyst in the reaction.

[0020] According to the present invention, in some embodiments, the specific surface area of ​​the catalyst is 20-400 m². 2 g -1 For example, 20m 2 g -1 30m 2 g -1 40m 2 g -1 50m 2 g -1 60m 2 g -1 100m 2 g -1 150m 2 g -1 160m 2 g -1 200m 2 g -1 250m 2 g -1 300m 2 g-1 400m 2 g -1 Preferably 50-150m 2 g -1 The catalysts described in the aforementioned embodiments can significantly improve the catalytic activity of the catalyst in the reaction.

[0021] In this invention, it should be noted that when preparing the catalyst, a certain amount of catalyst is generally prepared. The particle size and / or specific surface area of ​​the prepared catalyst can be a fixed value or a range value. Generally, it is a range value, that is, the range value composed of the maximum and minimum particle size of the catalyst in one field of view on XRD. The specific surface area of ​​the catalyst is the range value composed of the maximum and minimum specific surface areas of the prepared catalyst.

[0022] According to the present invention, it is understood that the catalyst of the present invention comprises a metallic portion Co and W and a non-metallic portion NC. In some embodiments, the mass ratio of the metallic portion Co and W to the non-metallic portion NC, calculated as elements, in the catalyst is (0.8-10):1, preferably (0.85-2):1. The catalyst under the aforementioned embodiments has a more stable structure.

[0023] In the catalyst, Co is calculated as elemental Co, and W is calculated as elemental W. The mass ratio of Co to W is 1-2:1, for example, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.5:1, 1.6:1, 2:1, or any range of the above values. The catalyst under the aforementioned embodiments can significantly improve the catalytic activity and stability of the catalyst in the reaction.

[0024] In this invention, the content of elements can be tested by ICP.

[0025] In this invention, as mentioned above, metal-organic frameworks (MOFs) are precursors to NC. A second aspect of this invention provides a method for preparing the bimetallic site CoW-NC catalyst described in this invention. The method includes: carbonizing and reducing a nitrogen-containing metal-organic framework containing W and Co bimetals to obtain the bimetallic site CoW-NC catalyst; wherein the carbonization and reduction conditions include: a carbonization temperature greater than 150°C.

[0026] The catalyst preparation method provided by this invention uses nitrogen-containing metal-organic frameworks (MOFs) containing W and Co bimetals to carry out carbonization and reduction at a certain carbonization temperature. The resulting catalyst has excellent catalytic performance and stability. It can not only be used to directly prepare diols by one-pot catalytic hydrogenolysis, but also achieves excellent combined effects of feed conversion rate and diol selectivity. At the same time, the catalyst has good recyclability.

[0027] According to the present invention, in some embodiments, the carbonization reduction conditions include: carbonization reduction being carried out in a hydrogen-containing reducing atmosphere.

[0028] According to the present invention, in some preferred embodiments, the reducing atmosphere comprises 5-30% by volume hydrogen, with the balance being an inert gas (e.g., nitrogen or argon, preferably nitrogen). The catalyst prepared using the foregoing embodiments exhibits better combined effects of feedstock conversion and diol selectivity when used for the catalytic hydrogenolysis of polyhydroxy compounds.

[0029] According to the present invention, in some embodiments, the carbonization reduction conditions include: a carbonization temperature of 200-600°C, for example, 100°C, 250°C, 300°C, 400°C, 500°C, 600°C, or any combination thereof, preferably 250-500°C, more preferably 300-500°C; and a carbonization time of 1-24 h, preferably 2-10 h. By employing the aforementioned embodiments, the effect of fixing the valence state of the metal elements during the preparation process can be fully utilized, resulting in a catalyst with better catalytic performance. When used in the catalytic hydrogenolysis of polyhydroxy compounds, it can achieve a better overall effect of feedstock conversion rate and diol selectivity.

[0030] In this invention, W-Co bimetallic metal-organic framework materials refer to periodic three-dimensional porous crystalline materials formed by the self-assembly of W and Co metal ions and organic ligands. In some embodiments, the preparation method of the W-Co bimetallic organic framework material includes a solvothermal reaction in a raw material mixture containing a Co source, a W source, and a nitrogen-containing organic ligand. Using the aforementioned embodiments, W-Co bimetallic metal-organic framework materials with excellent performance can be obtained.

[0031] According to the present invention, in some preferred embodiments, the conditions for the solvothermal reaction include a reaction temperature of 100-180°C, preferably 120-160°C. By employing the foregoing embodiments, metal-organic framework materials containing W and Co bimetals with excellent performance can be obtained, thereby enabling the prepared catalyst to possess excellent catalytic activity and stability.

[0032] According to the present invention, in some preferred embodiments, the conditions for the solvothermal reaction include a reaction time of 24-240 h, preferably 48-168 h. By employing the foregoing embodiments, metal-organic framework materials containing W and Co bimetals with excellent performance can be obtained, thereby enabling the prepared catalyst to possess excellent catalytic activity and stability.

[0033] According to the present invention, there are no limitations on the equipment for carrying out the solvothermal reaction; it can be any existing device capable of realizing a solvothermal reaction, for example, the solvothermal reaction is carried out in a tetrafluoroethylene high-pressure reactor, and heating can be achieved using an oven.

[0034] According to the present invention, after the raw material mixture undergoes a solvothermal reaction, solvent and / or unreacted raw materials may still be present. In some embodiments, the preparation method of W and Co bimetallic organic framework materials further includes: washing and drying the solid material obtained from the solvothermal reaction; wherein, the solid material obtained from the solvothermal reaction can be obtained by separation and filtration. In the present invention, there are no restrictions on the aforementioned washing method, as long as the washing purpose can be achieved. For example, washing with water 2-5 times with low-boiling-point solvents such as ethanol and acetone; drying can be achieved by a drying oven, for example, drying in a drying oven at 60-90°C for 10-30 hours.

[0035] According to the present invention, there is no limitation on the type of Co source as long as the purpose of the present invention can be achieved, as long as it can provide Co ions for the metal-organic framework material. In some embodiments, the Co source is selected from at least one of cobalt acetate, cobalt nitrate, cobalt chloride and cobalt sulfate.

[0036] According to the present invention, there is no limitation on the type of W source as long as it can achieve the purpose of the present invention, as long as it can provide W ions for metal-organic framework materials. In some embodiments, the W source is selected from at least one of tungstic acid, ammonium metatungstate and tungsten oxide.

[0037] According to the present invention, in some embodiments, the nitrogen-containing organic ligand comprises 2-methylimidazole. By employing the aforementioned embodiments, a catalyst with better performance can ultimately be obtained.

[0038] According to the present invention, the raw material mixture containing Co source, W source and nitrogen-containing organic ligand refers to the raw material mixture obtained by mixing raw materials including Co source, W source and nitrogen-containing organic ligand with solvent. The mixing method is not particularly limited, and the Co source, W source, nitrogen-containing organic ligand and solvent can be obtained by sonicating for 0.2-2 hours.

[0039] According to the present invention, the solvent in the raw material mixture can be selected from a wide range, provided that the objective of the present invention can be achieved. In some embodiments, the solvent in the raw material mixture is selected from aprotic solvents. Using the aforementioned embodiments is beneficial to improving the catalytic activity of the catalyst, and when used for the catalytic hydrogenolysis of polyhydroxy compounds, it can achieve a better overall effect of raw material conversion rate and diol selectivity.

[0040] According to the present invention, in some preferred embodiments, the solvent in the raw material mixture is at least one of N,N-dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide, preferably N,N-dimethylformamide. Using the foregoing embodiments is beneficial for improving the catalytic activity of the catalyst, and when used for the catalytic hydrogenolysis of polyhydroxy compounds, it can achieve a better overall effect of raw material conversion rate and diol selectivity.

[0041] According to the present invention, in some embodiments, the Co source is calculated as Co element and the W source is calculated as W element, and the mass ratio of the Co source to the W source is 0.25-4:1, preferably 1-2:1. Using the aforementioned embodiments is beneficial to improving the catalytic activity of the catalyst, and when used for the catalytic hydrogenolysis of polyhydroxy compounds, it can achieve a better overall effect of feedstock conversion rate and diol selectivity.

[0042] According to the present invention, in some embodiments, the Co source is calculated as Co element and the W source is calculated as W element, and the mass ratio of the total mass of the Co source and the W source to the mass of the organic ligand is 0.15-24:1, preferably 1-10:1.

[0043] According to the present invention, as long as the purpose of the present invention can be achieved, the amount of solvent in the raw material mixture is not particularly limited, as long as the solvothermal reaction can proceed smoothly. In some embodiments, the total mass of Co source, W source and organic ligand in the solvent is 0.0025-1.7 g / mL, preferably 0.01-0.1 g / mL.

[0044] A third aspect of the present invention provides the application of the catalyst described herein in the catalytic hydrogenolysis of polyhydroxy compounds.

[0045] In this invention, the catalyst described herein is used for the catalytic hydrogenolysis of polyhydroxy compounds, which not only has good catalytic performance, but also good cycle stability.

[0046] A fourth aspect of the present invention provides a method for preparing diols from polyhydroxy compounds, the method comprising: catalytic hydrogenolysis of the polyhydroxy compound in the presence of hydrogen, water and the catalyst described in the present invention.

[0047] In this invention, the use of the catalyst described herein for the catalytic hydrogenolysis of polyhydroxy compounds not only achieves a better overall effect in terms of feed conversion rate and diol selectivity, but also the catalyst has good recyclability.

[0048] According to the present invention, there are no particular limitations on the amount of hydrogen, water, catalyst and polyhydroxy compound used, as long as it is conducive to the catalytic hydrogenolysis reaction of polyhydroxy compound.

[0049] According to the present invention, in some embodiments, the mass ratio of the polyhydroxy compound to the catalyst is 10-0.1:1, preferably 0.5-5:1.

[0050] According to the present invention, in some embodiments, the mass ratio of water to polyhydroxy compound is 4-1000:1, preferably 10-100:1.

[0051] According to the present invention, in some embodiments, the amount of hydrogen introduced is such that the reaction pressure is 0.5-10 MPa, preferably 1-6 MPa.

[0052] According to the present invention, the specific type of the polyhydroxy compound is not particularly limited, as long as it can be used to obtain a diol through catalytic hydrogenolysis. In some embodiments, the polyhydroxy compound includes at least one of cellulose, glucose, fructose and sorbitol.

[0053] According to the present invention, those skilled in the art will understand that the diols obtained include at least one of ethylene glycol, 1,2-propanediol, and 1,2-butanediol.

[0054] According to the present invention, in some embodiments, the conditions for catalytic hydrogenolysis include a reaction temperature of 150-300°C, preferably 200-245°C.

[0055] According to the present invention, in some embodiments, the conditions for catalytic hydrogenolysis include a reaction time of 0.5-12 h, preferably 0.5-4 h.

[0056] The present invention will be described in detail below through embodiments. In the following embodiments and comparative examples:

[0057] Glucose to diol conversion: 0.075 g catalyst, 0.25 g glucose, and 25 mL deionized water were added to a stirred high-pressure reactor. Hydrogen gas was purged three times, then the reactor was purged with hydrogen to 4 MPa and sealed. The temperature was raised to 245 °C using a programmed heating mantle, and the reactor was magnetically stirred and then stirred. The reaction was carried out at 245 °C for 1 h. Gas chromatography was used to quantitatively analyze the products in the reaction solution, and liquid chromatography was used to quantitatively analyze the raw materials. The conversion rate of glucose, the yield of the diol, and the selectivity of the diol were calculated according to the following formulas.

[0058] The reaction products (diols, such as ethylene glycol, propylene glycol, and butylene glycol) were qualitatively analyzed by gas chromatography-mass spectrometry (GC-MS), and the yields of the product diols (such as ethylene glycol, propylene glycol, and butylene glycol) and the conversion of the reaction substrate glucose were analyzed by gas chromatography (GC). The GC-MS system was an Agilent 7890A from Agilent Technologies, USA, with an HP-5 nonpolar capillary column (30 m, 0.53 mm). The GC system was an Agilent 7890B, with a flame ionization detector (FID) and an HP-INNOWAX capillary column (60 m, 0.25 mm).

[0059] Recyclability: The catalyst used for glucose to diol production is washed three times with ethanol and three times with deionized water, dried, and then recycled for the next reaction. The reaction is carried out under the same conditions as described above. This process is repeated multiple times. The conversion rate of glucose, the yield of diol, and the selectivity of diol are calculated according to the following formulas.

[0060] Glucose conversion rate % = (molar amount of glucose participating in the reaction) / (molar amount of glucose as the initial reaction substrate) × 100%.

[0061] The formula for calculating the yield of the product diols (ethylene glycol, propylene glycol, and butanediol) is as follows:

[0062] Yield % of the product diol = (number of carbon atoms corresponding to the molar amount of the diol produced in the reaction) / (number of carbon atoms corresponding to the molar amount of the initial substrate glucose) × 100%.

[0063] Selectivity of the product diol % = (number of carbon atoms corresponding to the molar amount of diol produced in the reaction) / (molar amount of glucose participating in the reaction) × 100%.

[0064] Example 1

[0065] Preparation of bimetallic site CoW-NC catalysts:

[0066] (1) 0.199 g cobalt acetate tetrahydrate, 0.096 g 2-methylimidazole, 0.05 g tungstic acid and 4 mL N,N-dimethylformamide were added to a 20 mL tetrafluoroethylene high-pressure reactor and sonicated for half an hour. Then the reactor was placed in an oven and heated to 160 °C for 144 hours. After the apparatus cooled to room temperature, the blue crystal product was separated and filtered. The product was washed three times with ethanol and deionized water respectively and dried in an 80 °C drying oven for 18 hours to obtain a metal-organic framework material containing W and Co bimetals.

[0067] (2) The obtained metal-organic framework material containing W and Co bimetals was heated to 450°C and calcined for 2 hours in a hydrogen atmosphere to obtain the bimetallic site CoW-NC catalyst.

[0068] SEM image of the catalyst is shown below. Figure 1 As shown, through Figure 1 The particle size of the catalyst can be 30-200 nm;

[0069] The specific surface area of ​​the catalyst is 50-150 m². 2 g -1 ;

[0070] In the catalyst, Co has a valence of 0 and W has a valence of +6; the content of Co is 30 wt%, the content of W is 24 wt%, and the content of NC is 46 wt%.

[0071] The XRD pattern of the catalyst is as follows Figure 2 As shown, this indicates that Co is mainly coordinated and loaded onto NC in the form of 0-valent nanoparticles;

[0072] XPS spectra of the catalyst are as follows Figure 3 As shown, this indicates that the W element does not exist on NC in the form of nanoparticles, but is loaded on NC in the form of +6 valence.

[0073] In experiments using it to convert glucose to diols, the glucose conversion rate was greater than 99%; the diol yield was 43%, the selectivity for ethylene glycol was 15.8%, the selectivity for 1,2-propanediol was 20.2%, and the selectivity for 1,2-butanediol was 7.2%. When the catalyst was recycled four times, the glucose conversion rate was greater than 99% in all four reactions; the diol yields in the first to fourth reactions were 43%, 41.5%, 41%, and 42.1%, respectively.

[0074] Example 2

[0075] The method of Example 1 is different in that, in step (1), N,N-dimethylformamide is replaced with dimethyl sulfoxide, and finally a bimetallic site CoW-NC catalyst is obtained.

[0076] SEM images of the catalyst and Figure 1 Similarly, the particle size of the catalyst is 30-200 nm;

[0077] The specific surface area of ​​the catalyst is 50-150 m². 2 g -1 ;

[0078] In the catalyst, Co has a valence of 0 and W has a valence of +6; the content of Co is 28 wt%, the content of W is 23 wt%, and the content of NC is 49 wt%.

[0079] In experiments using it to produce diols from glucose, the glucose conversion rate was greater than 99%; the diol yield was 41.2%, the selectivity for ethylene glycol was 15.3%, the selectivity for 1,2-propanediol was 18.9%, and the selectivity for 1,2-butanediol was 7%.

[0080] Example 3

[0081] The method of Example 1 is different in that step (2) the obtained metal-organic framework material containing W and Co bimetals is heated to 300°C in a hydrogen atmosphere to finally obtain the bimetallic site CoW-NC catalyst.

[0082] SEM images of the catalyst and Figure 1 Similarly, the particle size of the catalyst is 100-1000 nm;

[0083] The specific surface area of ​​the catalyst is 150-400 m². 2 g -1 ;

[0084] In the catalyst, Co has a valence of 0 and W has a valence of +6; the content of Co is 25 wt%, the content of W is 20 wt%, and the content of NC is 55 wt%.

[0085] In experiments using it to convert glucose into diols, the glucose conversion rate was greater than 99%; the diol yield was 37.2%, the selectivity for ethylene glycol was 13.2%, the selectivity for 1,2-propanediol was 17.3%, and the selectivity for 1,2-butanediol was 6.7%.

[0086] Example 4

[0087] The method of Example 1 is different in that step (2) the obtained metal-organic framework material containing W and Co bimetals is heated to 600°C in a hydrogen atmosphere to finally obtain the bimetallic site CoW-NC catalyst.

[0088] SEM images of the catalyst and Figure 1 Similarly, the particle size of the catalyst is 30-200 nm;

[0089] The specific surface area of ​​the catalyst is 30-100 m². 2 g -1 ;

[0090] In the catalyst, Co has a valence of 0 and W has a valence of +6; the content of Co is 40 wt%, the content of W is 32 wt%, and the content of NC is 28 wt%.

[0091] In experiments using it to produce diols from glucose, the glucose conversion rate was greater than 99%; the diol yield was 35.8%.

[0092] Example 5

[0093] The method of Example 1 differs in that, in step (2), the obtained metal-organic framework material containing W and Co bimetals is heated to 800°C in a hydrogen atmosphere to finally obtain the bimetallic site CoW-NC catalyst.

[0094] SEM images of the catalyst and Figure 1 Similarly, the particle size of the catalyst is 30-200 nm;

[0095] The specific surface area of ​​the catalyst is 30-100 m². 2 g -1 ;

[0096] In the catalyst, Co has a valence of 0 and W has a valence of +6; the content of Co is 46 wt%, the content of W is 36 wt%, and the content of NC is 18 wt%.

[0097] In experiments using it to produce diols from glucose, the glucose conversion rate was greater than 99%; the diol yield was 28.1%.

[0098] Example 6

[0099] The method of Example 1 is different in that, in step (1), "0.199g cobalt acetate tetrahydrate, 0.096g 2-methylimidazole, 0.05g tungstic acid and 4mL N,N-dimethylformamide are added to a 20mL tetrafluoroethylene high-pressure reactor" is replaced with 1g cobalt acetate tetrahydrate, 0.480g 2-methylimidazole, 0.250g tungstic acid and 20mL N,N-dimethylformamide are added to a 100mL tetrafluoroethylene high-pressure reactor, and finally the bimetallic site CoW-NC catalyst is obtained.

[0100] SEM images of the catalyst and Figure 1 Similarly, the particle size of the catalyst is 30-200 nm;

[0101] The specific surface area of ​​the catalyst is 50-150 m². 2 g -1 ;

[0102] In the catalyst, Co has a valence of 0 and W has a valence of +6; the content of Co is 30 wt%, the content of W is 24 wt%, and the content of NC is 46 wt%.

[0103] In experiments using it to produce diols from glucose, the glucose conversion rate was greater than 99%; the diol yield was 42.7%.

[0104] Example 7

[0105] The method of Example 1 is different in that, in step (1), "0.199g cobalt acetate tetrahydrate, 0.096g 2-methylimidazole, 0.05g tungstic acid and 4mL N,N-dimethylformamide are added to a 20mL tetrafluoroethylene high-pressure reactor" is replaced with 3g cobalt acetate tetrahydrate, 0.480g 2-methylimidazole, 0.250g tungstic acid and 20mL N,N-dimethylformamide are added to a 100mL tetrafluoroethylene high-pressure reactor, and finally the bimetallic site CoW-NC catalyst is obtained.

[0106] SEM images of the catalyst and Figure 1 Similarly, the catalyst particle size is 50-100 nm;

[0107] The specific surface area of ​​the catalyst is 50-150 m². 2 g -1 ;

[0108] In the catalyst, Co has a valence of 0 and W has a valence of +6; the content of Co is 50 wt%, the content of W is 12 wt%, and the content of NC is 38 wt%.

[0109] In experiments using it to produce diols from glucose, the glucose conversion rate was greater than 99%; the diol yield was 35.3%.

[0110] Example 8

[0111] The method of Example 1 is different in that, in step (2), “heating to 450°C in a hydrogen atmosphere” is replaced by heating to 450°C in a hydrogen-argon mixture atmosphere containing 10% by volume of hydrogen, and finally the bimetallic site CoW-NC catalyst is obtained.

[0112] SEM images of the catalyst and Figure 1 Similarly, the particle size of the catalyst is 30-200 nm;

[0113] The specific surface area of ​​the catalyst is 50-150 m². 2 g -1 ;

[0114] In the catalyst, Co has a valence of 0 and W has a valence of +6; the content of Co is 24 wt%, the content of W is 23 wt%, and the content of NC is 53 wt%.

[0115] In experiments using it to convert glucose to diols, the conversion rate of glucose was greater than 99% and the yield of diols was 50%. When the catalyst was recycled four times, the conversion rate of glucose was greater than 99% in all four reactions. The yields of diols in the first to fourth reactions were 50%, 49.6%, 48.2%, and 48%, respectively.

[0116] Comparative Example 1

[0117] 0.05 g of tungstic acid and 0.199 g of cobalt acetate tetrahydrate were dissolved in 3 mL of deionized water by heating and sonicated for half an hour. The above solution was added to 0.5 g of activated carbon, shaken until uniformly mixed, and placed in an 80 °C drying oven for 8-12 h. The obtained sample was then heated to 400 °C and calcined for 1-3 h under a hydrogen atmosphere to obtain the CoW / AC catalyst.

[0118] The catalyst has a specific surface area of ​​800 m². 2 g -1 ;

[0119] In the catalyst, Co has a valence of 0 and W has a valence of +6; the content of Co is 12 wt%, the content of W is 9 wt%, and the content of activated carbon AC is 79 wt%.

[0120] In experiments using the catalyst to convert glucose to diols, the glucose conversion rate was greater than 99%; the diol yield was 10.4%; the selectivity for ethylene glycol was 6.8%; the selectivity for 1,2-propanediol was 3.4%; and the selectivity for 1,2-butanediol was 0.2%.

[0121] Comparative Example 2

[0122] 0.199 g of cobalt acetate tetrahydrate, 0.096 g of 2-methylimidazole, 0.05 g of tungstic acid, and 4 mL of N,N-dimethylformamide were added to a 20 mL tetrafluoroethylene high-pressure reactor. The reactor was sonicated for half an hour, then placed in an oven and heated to 160 °C for 144 hours. After the apparatus cooled to room temperature, a blue crystalline product was obtained. The product was washed three times with ethanol and three times with deionized water, and then dried in an 80 °C oven for 18 hours. The HZIF-CoW catalyst was obtained.

[0123] The catalyst particle size is 5000-10000 nm;

[0124] The catalyst has a specific surface area of ​​400 m². 2 g -1 ;

[0125] The XRD pattern of the catalyst is as follows Figure 2 As shown, this indicates that Co is not coordinated and loaded onto NC as 0-valent nanoparticles;

[0126] In the catalyst, Co has a +2 oxidation state and W has a +6 oxidation state; the content of Co is 23 wt%, the content of W is 18 wt%, and the content of NC is 59 wt%.

[0127] In experiments using the catalyst to convert glucose to diols, the glucose conversion rate was greater than 99%; the diol yield was 0.3%, the selectivity for ethylene glycol was 0.1%, the selectivity for 1,2-propanediol was 0.2%, and the selectivity for 1,2-butanediol was 0%.

[0128] Comparative Example 3

[0129] The method of Example 1 is different in that, in step (2), the obtained metal-organic framework material containing W and Co bimetals is heated to 150°C in a hydrogen atmosphere to finally obtain the bimetallic site CoW-NC catalyst.

[0130] SEM images of the catalyst and Figure 1 Similarly, the particle size of the catalyst is 1000-10000 nm;

[0131] The specific surface area of ​​the catalyst is 300-400 m². 2 g -1 ;

[0132] In the catalyst, Co has a +2 oxidation state and W has a +6 oxidation state; the content of Co is 23 wt%, the content of W is 18 wt%, and the content of NC is 59 wt%.

[0133] In experiments using the catalyst to convert glucose to diols, the glucose conversion rate was greater than 99%; the diol yield was 9.1%, the selectivity for ethylene glycol was 3%, the selectivity for 1,2-propanediol was 4.2%, and the selectivity for 1,2-butanediol was 1.9%.

[0134] Comparative Example 4

[0135] Preparation of bimetallic site ZnW-NC catalysts:

[0136] (1) 0.176 g zinc acetate dihydrate, 0.096 g 2-methylimidazole, 0.05 g tungstic acid and 4 mL N,N-dimethylformamide were added to a 20 mL tetrafluoroethylene high-pressure reactor and sonicated for half an hour. Then the reactor was placed in an oven and heated to 160 °C for 144 hours. After the apparatus cooled to room temperature, a colorless crystalline product was obtained. The product was washed three times with ethanol and deionized water, and then dried in an 80 °C drying oven for 18 hours to obtain a metal-organic framework material containing Zn and W bimetals.

[0137] (2) The obtained metal-organic framework material containing Zn and W bimetals was heated to 450°C and calcined for 2 hours in a hydrogen atmosphere to obtain the bimetallic site ZnW-NC catalyst.

[0138] The catalyst has a particle size of 1000 nm;

[0139] The specific surface area of ​​the catalyst is 100-200 m². 2 g -1 ;

[0140] In the catalyst, Zn has a valence of 0 and W has a valence of +6; the content of Zn is 29 wt%, the content of W is 23 wt%, and the content of NC is 48 wt%.

[0141] In experiments using the catalyst to produce diols from glucose, the conversion rate of glucose was greater than 99%; the yield of diols was 0.5%.

[0142] The results from the above examples and comparative examples show that the catalyst of the present invention has good catalytic performance, and when used for the catalytic hydrogenolysis of polyhydroxy compounds, it can achieve a better overall effect of conversion rate and diol selectivity.

[0143] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A bimetallic CoW-NC catalyst, characterized in that, The bimetallic site CoW-NC catalyst is a material formed by the self-assembly of Co and W with nitrogen-doped porous carbon NC, wherein Co is in the reduced state in the catalyst.

2. The catalyst according to claim 1, wherein, In the catalyst, W has a chemical oxidation state of +6; and / or The catalyst has a particle size of 30-1000 nm; and / or The catalyst has a specific surface area of ​​20-400 m². 2 g -1 .

3. The catalyst according to claim 2, wherein, The catalyst has a particle size of 30-200 nm.

4. The catalyst according to claim 1, wherein, In the catalyst, the mass ratio of the metal portion (Co, W) to the non-metal portion (NC), calculated by element, is 0.8-10:1; and / or In the catalyst, Co is calculated as Co element and W is calculated as W element, and the mass ratio of Co to W is 1-2:

1.

5. The catalyst according to claim 4, wherein, In the catalyst, the mass ratio of the metal portion (Co, W) to the non-metal portion (NC) is 0.85-2:

1.

6. A method for preparing a bimetallic site CoW-NC catalyst according to any one of claims 1-5, characterized in that, The preparation method includes: carbonizing and reducing a nitrogen-containing metal-organic framework material containing W and Co bimetals to obtain a bimetallic site CoW-NC catalyst; The conditions for carbonization reduction include a carbonization temperature greater than 150°C.

7. The preparation method according to claim 6, wherein, The conditions for the carbonization reduction include: Carbonization reduction is carried out in a reducing atmosphere containing hydrogen; and / or The carbonization temperature is 200-600℃; and / or Carbonization time is 1-24 hours.

8. The preparation method according to claim 7, wherein, The conditions for the carbonization reduction include: The reducing atmosphere comprises 5-30% by volume hydrogen, with the balance being an inert gas; and / or The carbonization temperature is 250-500℃; and / or Carbonization time is 2-10 hours.

9. The preparation method according to claim 6, wherein, The preparation method of the W and Co bimetallic organic framework material includes: carrying out a solvothermal reaction in a raw material mixture containing a Co source, a W source and a nitrogen-containing organic ligand; The preparation method of W and Co bimetallic organic framework materials also includes washing and drying the solid material obtained by solvothermal reaction.

10. The preparation method according to claim 9, wherein, The conditions for the solvothermal reaction include: a reaction temperature of 100-180℃; and / or a reaction time of 24-240h.

11. The preparation method according to claim 10, wherein, The conditions for the solvothermal reaction include: a reaction temperature of 120-160℃; and / or a reaction time of 48-168h.

12. The preparation method according to claim 9, wherein, The Co source is selected from at least one of cobalt acetate, cobalt nitrate, cobalt chloride, and cobalt sulfate; and / or The W source is selected from at least one of tungstic acid, ammonium metatungstate, and tungsten oxide; and / or The nitrogen-containing organic ligand includes 2-methylimidazole; and / or The solvent in the raw material mixture is selected from aprotic solvents.

13. The preparation method according to claim 12, wherein, The solvent in the raw material mixture is at least one of N,N-dimethylformamide, dimethyl sulfoxide, and N,N-dimethylacetamide.

14. The preparation method according to claim 13, wherein, The solvent in the raw material mixture is N,N-dimethylformamide and / or dimethyl sulfoxide.

15. The preparation method according to claim 9, wherein, The Co source is calculated as Co element and the W source as W element, wherein the mass ratio of the Co source to the W source is 0.25-4:1; and / or The Co source is calculated as Co element and the W source is calculated as W element, and the total mass of the Co source and W source is in a mass ratio of 0.15-24:1 to the mass of the organic ligand.

16. The preparation method according to claim 15, wherein, The Co source is calculated based on Co elemental content, and the W source is calculated based on W elemental content, wherein the mass ratio of the Co source to the W source is 1-2:1; and / or The Co source is calculated as Co element and the W source as W element, and the total mass ratio of the Co source and W source to the organic ligand is 1-10:

1.

17. The use of the catalyst according to any one of claims 1-5 in the catalytic hydrogenolysis of polyhydroxy compounds.

18. A method for preparing diols from polyhydroxy compounds, characterized in that, The method includes: The polyhydroxy compound undergoes catalytic hydrogenolysis in the presence of hydrogen, water, and the catalyst described in any one of claims 1-5.

19. The method according to claim 18, wherein, The mass ratio of the polyhydroxy compound to the catalyst is 10-0.1:1; and / or The mass ratio of water to the polyhydroxy compound is 4-1000:1; and / or The amount of hydrogen introduced is such that the reaction pressure is 0.5-10 MPa; and / or The polyhydroxy compound includes at least one of cellulose, glucose, fructose, and sorbitol; and / or The conditions for the catalytic hydrogenolysis include: a reaction temperature of 150-300℃; and / or a reaction time of 0.5-12h.

20. The method according to claim 19, wherein, The mass ratio of the polyhydroxy compound to the catalyst is 0.5-5:1; and / or The mass ratio of water to the polyhydroxy compound is 10-100:1; and / or The amount of hydrogen introduced makes the reaction pressure 1-6 MPa; and / or The conditions for the catalytic hydrogenolysis include: a reaction temperature of 200-245℃; and / or a reaction time of 0.5-4h.

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