Microporous carbon sphere confinement cobalt / cobalt oxide core-noble metal shell nano composite material and preparation method and application thereof

Abstract

The invention discloses a microporous carbon sphere confinement cobalt / cobalt oxide core-noble metal shell nano composite material as well as a preparation method and application thereof, and belongs to the technical field of catalysts. Non-noble metal cobalt and cobalt oxide are used as acidic active sites, noble metal is used as hydrogen dissociation active sites, and the noble metal is deposited on the surface of the cobalt / cobalt oxide core to form a noble metal shell by utilizing a replacement reaction, so that on one hand, the catalytic action of the noble metal can be fully exerted, and on the other hand, the non-noble metal cobalt is used for replacing part of the noble metal; the formed cobalt / cobalt oxide core-noble metal shell is confined in the microporous carbon spheres, so that the stability of the catalyst is improved and the loss of cobalt and noble metal is reduced through the confinement of the microporous carbon spheres; finally, the microporous carbon sphere confinement cobalt / cobalt oxide core-noble metal shell nano composite material which has excellent catalytic hydrogenolysis activity, selectivity and stability and is used for biomass platform molecule hydrogenolysis upgrading is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a microporous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite material, a preparation method thereof, and an application thereof. Background Art

[0002] Since the discovery of fossil fuels, they have always been the core driving force for global economic progress, industrialization, and technological innovation. However, their non-renewable and environmentally damaging drawbacks are quite obvious. Biomass, as a low-cost and abundant renewable resource, is an ideal substitute for fossil resources and has received extensive attention in recent years. Many furan derivatives can be effectively obtained from cellulose and hemicellulose, which are the main components of biomass, such as 5-hydroxymethylfurfural (5-HMF), furfural, and 5-methylfurfural (5-MF). They are platform molecules for the production of other value-added chemicals, and high-value-added chemicals and organic synthesis intermediates can be prepared by performing operations such as hydrogenation, deoxygenation, and hydrolysis on biomass raw materials.

[0003] Improving the hydrodeoxygenation activity of biomass raw materials and the selectivity of target products is the key point and difficulty. In the reported studies, metal oxides or activated carbon-supported metal elements are mainly used as catalysts. Noble metal nanoparticles themselves have excellent properties such as redox catalytic performance, photosensitive ability, and electrical conductivity. Therefore, highly efficient noble metal catalysts such as Pd, Pt, and Ir have been developed for the hydrogenolysis of biomass platform molecules. However, limited by adverse factors such as the reserves, cost, and stability of noble metals, the application cost of noble metal catalysts has always been high, restricting the application of noble metal catalysts.

[0004] Therefore, how to further reduce the amount of noble metal used while ensuring the activity and selectivity of the catalyst has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a microporous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite material, a preparation method thereof, and an application thereof.

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

[0007] The present invention provides a micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite. The micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite comprises a micro-porous carbon sphere, cobalt, cobalt oxide and a noble metal; the cobalt is partially coated with the noble metal, and the uncoated cobalt forms cobalt oxide. The cobalt, cobalt oxide and noble metal form a cobalt / cobalt oxide core-noble metal shell, and the cobalt / cobalt oxide core-noble metal shell is confined in the micro-porous carbon sphere; the content of the noble metal in the micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite is 5-8 wt.%; the content of cobalt in the micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite is 5-8 wt.%; the pore diameter of the micro-porous carbon sphere is 0.7-1.5 nm, the particle size of the cobalt is 8-15 nm, and the coating rate of the partial coating is 50-80%.

[0008] Preferably, the noble metal comprises one of Ag, Pt, Pd, and Ru.

[0009] The present invention provides a method for preparing the micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite as described in the above technical solution, comprising the following steps: placing the micro-porous carbon sphere-confined cobalt composite and ethanol in a closed reaction kettle, introducing hydrogen for pre-reduction, then introducing nitrogen into the closed reaction kettle to change the hydrogen atmosphere in the kettle to nitrogen, then adding an aqueous solution of a noble metal precursor and using a cyclic vacuum pump to maintain a negative pressure in the kettle for a displacement reaction. After the reaction is completed, centrifugation is carried out, followed by vacuum drying, and finally the micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite is obtained.

[0010] Preferably, the temperature of the displacement reaction is ≤25 °C, the time is 48 h, the pressure is -0.1 MPa, and the atmosphere is nitrogen.

[0011] Preferably, the dosage ratio of the micro-porous carbon sphere-confined cobalt composite, ethanol and the aqueous solution of the noble metal precursor is 0.1 g∶10 mL∶(1.57-2.71) mL; the concentration of the aqueous solution of the noble metal precursor is 1 g / 100 mL.

[0012] The present invention also provides an application of the micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite as described in the above technical solution in the catalytic hydrogenolysis of biomass platform molecules.

[0013] Compared with the prior art, the present invention has the following advantages and technical effects:

[0014] In the present invention, non-precious metal cobalt and cobalt oxide are used as acidic active sites, and precious metal is used as hydrogen dissociation active site. The precious metal is deposited on the surface of the cobalt / cobalt oxide core through a displacement reaction to form a precious metal shell. On the one hand, the catalytic effect of the precious metal can be fully exerted. On the other hand, non-precious metal cobalt is used to replace part of the precious metal, significantly reducing the cost of the catalyst. And the formed cobalt / cobalt oxide core-precious metal shell is confined in the microporous carbon spheres. Through the confinement of the microporous carbon spheres, the stability of the catalyst is increased, and the loss of cobalt and precious metal is reduced. Finally, a microporous carbon sphere-confined cobalt / cobalt oxide core-precious metal shell nanocomposite with excellent catalytic hydrogenolysis activity, selectivity and stability for the hydrogenolysis upgrading of biomass platform molecules is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0016] Figure 1 XRD patterns of Pt-Co / CoO@MCS prepared in Example 1 of the present invention and Co / CoO@MCS in step (3) of Example 1;

[0017] Figure 2 HRTEM image of Pt-Co / CoO@MCS prepared in Example 1 of the present invention;

[0018] Figure 3 Mapping image of Pt-Co / CoO@MCS prepared in Example 1 of the present invention;

[0019] Figure 4 BET diagram of Pt-Co / CoO@MCS prepared in Example 1 of the present invention;

[0020] Figure 5 Schematic structural diagram of Pt-Co / CoO@MCS prepared in Example 1 of the present invention;

[0021] Figure 6 Performance diagram of Pt-Co / CoO@MCS prepared in Example 1 of the present invention for the production of 2-methylfuran from furfural;

[0022] Figure 7 Performance diagrams of microporous carbon sphere-confined cobalt / cobalt oxide core-precious metal shell nanocomposites prepared in Examples 2-4 of the present invention for the production of 2-methylfuran from furfural;

[0023] Figure 8 Performance diagram of the composite material prepared in Comparative Example 1 for the production of 2-methylfuran from furfural. DETAILED DESCRIPTION OF THE INVENTION

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] The embodiments of the present invention provide a micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite. The micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite includes micro-porous carbon spheres, cobalt, cobalt oxide, and noble metals; the cobalt is partially coated with noble metals, and the uncoated cobalt forms cobalt oxide. The cobalt, cobalt oxide, and noble metals form a cobalt / cobalt oxide core-noble metal shell, and the cobalt / cobalt oxide core-noble metal shell is confined in the micro-porous carbon spheres; the content of noble metals in the micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite is 5-8 wt.%; the content of cobalt in the micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite is 5-8 wt.%; the pore diameter of the micro-porous carbon spheres is 0.7-1.5 nm, the particle diameter of the cobalt is 8-15 nm, and the coating rate of the partial coating is 50-80%. By combining micro-porous carbon spheres, cobalt, cobalt oxide, and noble metals, the present invention gives full play to the synergistic effect of the several components, and at the same time limits the pore diameters of the micro-porous carbon spheres and cobalt, reducing the loss of cobalt and noble metals. When the total content of cobalt and noble metals is relatively low, the catalytic hydrogenolysis activity of the nanocomposite is ensured.

[0027] In a preferred embodiment, the noble metal includes one of Ag, Pt, Pd, and Ru. The noble metal in the present invention serves as a hydrogen dissociation active site. Coating the cobalt / cobalt oxide core with it as a shell layer has the advantages of saving the amount of noble metal used and enhancing the ability of the catalyst to hydrogenolyze biomass platform molecules.

[0028] The present invention provides a method for preparing the micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite described in the above technical solution, including the following steps: placing the micro-porous carbon sphere-confined cobalt composite and ethanol in a closed reaction kettle, introducing hydrogen for pre-reduction, then introducing nitrogen into the closed reaction kettle to change the hydrogen atmosphere in the kettle to nitrogen, then adding an aqueous solution of a noble metal precursor and using a circulating vacuum pump to maintain a negative pressure in the kettle for a displacement reaction. After the reaction is completed, centrifugation and vacuum drying are carried out, and finally the micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite is obtained.

[0029] In the present invention, the microporous carbon sphere-confined cobalt composite material and ethanol are placed in a closed reaction kettle, and hydrogen is introduced for pre-reduction to remove the oxide layer on the surface of the cobalt core, so that the surface of the cobalt core is elemental cobalt; nitrogen is introduced into the closed reaction kettle to keep the negative pressure inside the kettle, and vacuum-assisted impregnation is used to promote the aqueous solution of the noble metal precursor to enter the pores of the microporous carbon, and then a displacement reaction occurs with the elemental cobalt in the pores to form a noble metal shell on the cobalt core. The cobalt is partially coated with the noble metal, and the uncoated cobalt is easily oxidized due to its small particle size and large specific surface area, and cobalt oxide is formed by air oxidation, thus obtaining the microporous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite material.

[0030] In a preferred embodiment, the temperature of the pre-reduction is 120 °C, the time is 5 h, the pressure is 1.0 MPa, and the atmosphere is hydrogen.

[0031] In a preferred embodiment, the temperature of the displacement reaction is ≤25 °C, and more preferably 10 - 25 °C; the time of the displacement reaction is 48 h, the pressure is -0.1 MPa, and the atmosphere is nitrogen. In the present invention, both the temperature and time of the displacement reaction have a great influence on the formation of the noble metal shell. If the reaction temperature is too high, the noble metal in the aqueous solution of the noble metal precursor is likely to form a noble metal sol, and if the reaction temperature is too low, the displacement will not succeed; if the reaction time is too long, the noble metal shell layer will be too thick or the shell layer thickness will be uneven, and if the reaction time is too short, the noble metal coverage rate will not be high and an effective noble metal shell layer cannot be formed.

[0032] In a preferred embodiment, the dosage ratio of the microporous carbon sphere-confined cobalt composite material, ethanol and the aqueous solution of the noble metal precursor is 0.1 g∶10 mL∶(1.57 - 2.71) mL; the concentration of the aqueous solution of the noble metal precursor is 1 g / 100 mL.

[0033] In a preferred embodiment, the preparation method of the microporous carbon sphere-confined cobalt composite material comprises the following steps: a cobalt precursor, trimesic acid and a solvent are mixed and then subjected to hydrothermal synthesis, pyrolysis, acid etching and reduction in sequence to obtain the microporous carbon sphere-confined cobalt composite material.

[0034] In a preferred embodiment, the dosage ratio of the cobalt precursor, trimesic acid and the solvent is 1.04 g∶1.04 g∶60 mL; the cobalt precursor is cobalt nitrate hexahydrate, and the solvent is ethanol.

[0035] In a preferred embodiment, the mixing method is stirring; the mixing time is 60 min.

[0036] In a preferred embodiment, the temperature of the hydrothermal synthesis is 150 °C and the time is 12 h.

[0037] In a preferred embodiment, the pyrolysis is specifically as follows: heating to 650 °C at a heating rate of 5 °C / min in an argon atmosphere and holding for 2 h.

[0038] In a preferred embodiment, the reagent for acid etching is nitric acid, the concentration of the nitric acid is 4 mol / L, and the dosage ratio of the nitric acid to the obtained pyrolysis product is 10 mL∶0.2 g; the temperature of the acid etching is 55 °C and the time is 2 h.

[0039] In a preferred embodiment, the reduction is specifically as follows: heating to 500 °C at a heating rate of 5 °C / min in a 5% H 2 / Ar mixed gas and holding for 2 h.

[0040] The present invention also provides an application of the microporous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite material described in the above technical solution in the catalytic hydrogenolysis of biomass platform molecules.

[0041] In a preferred embodiment, the application is specifically the preparation of 2-methylfuran from furfural.

[0042] In the embodiments of the present invention, room temperature refers to "25±2 °C".

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

[0044] Example 1

[0045] A microporous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite material is composed of microporous carbon spheres, Co, CoO and Pt; Co is partially coated by Pt, and the uncoated Co forms CoO, and Co, CoO and Pt form a Co / CoO core-Pt shell, and the Co / CoO core-Pt shell is confined in the microporous carbon spheres; the content of Pt in the composite material is 8 wt.%, the content of Co is 8 wt.%, the pore diameter of the microporous carbon spheres is 1.2 nm, the particle diameter of Co is 9 nm, and the coating rate of Pt is 60-65%.

[0046] The preparation method of the microporous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite material is as follows:

[0047] (1) Weigh 1.04 g of cobalt nitrate hexahydrate and 1.04 g of trimesic acid, dissolve them in 60 mL of ethanol, stir for 60 min to obtain solution A; place the obtained solution A in a hydrothermal autoclave, carry out hydrothermal synthesis at 150 °C for 12 h, cool to room temperature, separate the product, wash it 4 times with ethanol, and dry it at 80 °C to obtain the Co-MOF precursor material.

[0048] (2) The Co-MOF precursor material obtained in step (1) was placed in a tube furnace. Under an argon atmosphere, it was heated to 650 °C at a heating rate of 5 °C / min and held for 2 h to obtain Co@MC nanoparticles with a Co content of 80 wt.%.

[0049] (3) 0.2 g of the Co@MC nanoparticles obtained in step (2) was placed in a beaker, and 10 mL of a nitric acid solution with a concentration of 4 mol / L was added. It was stirred at 55 °C for 2 h. After stirring, it was washed 3 times with water and ethanol respectively, and dried at 60 °C under vacuum to obtain an intermediate product; the obtained intermediate product was placed in a tube furnace. In a 5% H 2 / Ar mixed gas, it was heated to 500 °C at a heating rate of 5 °C / min and held for 2 h, and then naturally cooled to obtain Co@MCS with a Co content of 16 wt.%.

[0050] (4) 0.1 g of the Co@MCS obtained in step (3) and 10 mL of ethanol were placed in a closed reaction kettle, and hydrogen was introduced. It was pre-reduced at 1.0 MPa hydrogen and 120 °C for 5 h. Then, nitrogen was introduced into the closed reaction kettle to change the hydrogen atmosphere in the kettle to nitrogen. 2.71 mL of an aqueous solution of chloroplatinic acid with a concentration of 1 g / 100 mL was added and the pressure in the kettle was maintained at -0.1 MPa using a circulating vacuum pump. Then, it was stirred and displaced at 10 °C for 48 h. After stirring, it was washed once with ethanol and dried at 50 °C under vacuum to obtain a microporous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite (Pt-Co / CoO@MCS) with a Co content of 8 wt.% and a Pt content of 8 wt.%.

[0051] Figure 1 XRD patterns of the Pt-Co / CoO@MCS prepared in Example 1 and the Co@MCS in step (3) of Example 1. As Figure 1 can be seen, the peak of Co is at 44°, the peak of Pt is at 39.6°, and the peak of CoO cannot be seen, which may be due to too low content. By comparing the XRD curves with the standard cards, it can be known that after replacement, the coverage rate of Pt is relatively high and the peak intensity of Co is low, indicating that Pt is on the surface of Co. X-rays first pass through Pt and then reach Co, and the peak of Pt in the figure is slightly shifted, which proves the metal interaction between them from the side.

[0052] Figure 2 HRTEM image of the Pt-Co / CoO@MCS prepared in Example 1 of the present invention. As Figure 2 can be seen, the morphology of this nanocomposite is independent spheres, and there are many pores on the surface of the spheres. The diameter of the spheres is about 2 μm.

[0053] Figure 3Mapping diagram of Pt-Co / CoO@MCS prepared in Example 1 of the present invention; in the figure, the distribution diagrams of Pt element, C element, O element, and Co element are shown in sequence. Judging from the distribution of platinum and cobalt, the distributions of these two elements are relatively uniform, conforming to the spherical structure of the cobalt / cobalt oxide core-noble metal shell layer.

[0054] Figure 4 BET diagram of Pt-Co / CoO@MCS prepared in Example 1 of the present invention. It can be seen from Figure 4 that the pore diameters of the micropores in the microporous carbon spheres are all below 2 nm.

[0055] Figure 5 Schematic structural diagram of Pt-Co / CoO@MCS prepared in Example 1 of the present invention. It can be seen from Figure 5 that Pt-Co / CoO@MCS prepared in Example 1 is composed of microporous carbon spheres, Co, CoO, and Pt. Co is partially coated by Pt, and the uncoated Co forms CoO. Co, CoO, and Pt form a Co / CoO core-Pt shell, and the Co / CoO core-Pt shell is confined in the microporous carbon spheres.

[0056] Example 2

[0057] The difference from Example 1 is that the chloroplatinic acid aqueous solution in step (4) is replaced with an aqueous silver nitrate solution with the same concentration and a volume of 1.57 mL, and Ag-Co / CoO@MCS with a Co content of 8 wt.% and an Ag content of 8 wt.% is obtained.

[0058] Example 3

[0059] The difference from Example 1 is that the chloroplatinic acid aqueous solution in step (4) is replaced with an aqueous palladium dichloride solution with the same concentration and a volume of 1.67 mL, and Pd-Co / CoO@MCS with a Co content of 8 wt.% and a Pd content of 8 wt.% is obtained.

[0060] Example 4

[0061] The difference from Example 1 is that the chloroplatinic acid aqueous solution in step (4) is replaced with an aqueous ruthenium trichloride solution with the same concentration and a volume of 2.3 mL, and Ru-Co / CoO@MCS with a Co content of 8 wt.% and a Ru content of 8 wt.% is obtained.

[0062] Comparative Example 1

[0063] The difference from Example 1 is that step (4) is omitted, and the remaining steps are the same as those in Example 1.

[0064] Comparative Example 2

[0065] (1) Weigh 1.04 g of benzene-1,3,5-tricarboxylic acid and dissolve it in 60 mL of ethanol. Stir for 60 min, then place it in a hydrothermal autoclave and carry out hydrothermal synthesis at 150 °C for 12 h. Cool to room temperature and dry at 80 °C to remove ethanol.

[0066] (2) Place the material obtained in step (1) in a tube furnace. Under an argon atmosphere, heat it to 650 °C at a heating rate of 5 °C / min and hold for 2 h to obtain MC nanoparticles.

[0067] (3) Place 0.2 g of the MC nanoparticles obtained in step (2) in a beaker, add 10 mL of a nitric acid solution with a concentration of 4 mol / L, stir at 55 °C for 2 h. After stirring, wash it 3 times with water and ethanol respectively, dry it under vacuum at 60 °C to obtain an intermediate product; place the obtained intermediate product in a tube furnace. In a 5% H 2 / Ar mixed gas, heat it to 500 °C at a heating rate of 5 °C / min and hold for 2 h, and then cool it naturally to obtain MCS.

[0068] Comparative Example 3

[0069] The difference from Example 1 is that in step (4), stir and displace for 48 h at 50 °C, and the remaining steps are the same as in Example 1.

[0070] Comparative Example 4

[0071] The difference from Example 1 is that in step (4), stir and displace for 48 h at 5 °C, and the remaining steps are the same as in Example 1.

[0072] Comparative Example 5

[0073] The difference from Example 1 is that in step (4), stir and displace for 40 h at 10 °C, and the remaining steps are the same as in Example 1.

[0074] Comparative Example 6

[0075] The difference from Example 1 is that in step (4), stir and displace for 60 h at 10 °C, and the remaining steps are the same as in Example 1.

[0076] Comparative Example 7

[0077] The difference from Example 1 is that after step (4), place Pt-Co / CoO@MCS in a muffle furnace at 600 °C and calcine for 2 h, then place it in a tube furnace at 400 °C and reduce it for 3 h. The heating rate is 5 °C / min, and the atmosphere is 10% H 2 / Ar.

[0078] Application Example 1

[0079] Use the Pt-Co / CoO@MCS prepared in Example 1 for the production of 2-methylfuran from furfural. The specific process is as follows:

[0080] Weigh 50 mg of Pt-Co / CoO@MCS and 0.192 g of furfural separately and place them in different reaction vessels. Then, add 10 mL of ethanol as a solvent to each reaction vessel, and simultaneously add 0.1 g of dodecane as an internal standard. Charge 0.5 MPa of hydrogen into each reaction vessel to displace the residual air in the reaction vessel, repeat this 5 times, then charge 1 MPa of hydrogen. Then, use a heating jacket to heat each reaction vessel to 70 - 110 °C respectively, and stir and react at a rotation speed of 800 rpm for 1 h. After the reaction is completed, take out the reaction vessel from the heating jacket, let it cool to room temperature and then release the pressure. Then, use a filter membrane to separate the solid and liquid in the liquid in the reaction vessel. The obtained liquid is a mixed liquid containing 2-methylfuran.

[0081] Analyze the liquid obtained in Application Example 1 by gas chromatography, calculate the conversion rate and selectivity, and the results are shown in Figure 6 。

[0082] Figure 6 It is a performance graph of Pt-Co / CoO@MCS prepared in Example 1 for the production of 2-methylfuran from furfural. As Figure 6 can be seen, when the reaction temperature is 90 - 110 °C, the selectivity of 2-methylfuran is above 80%; considering the yield and selectivity of 2-methylfuran, the reaction temperature of 100 °C is more appropriate. It shows that the prepared composite material has excellent catalytic hydrogenolysis activity, excellent selectivity and stability under relatively mild conditions.

[0083] Application Example 2

[0084] Use the Ag-Co / CoO@MCS prepared in Example 2 for the production of 2-methylfuran from furfural. The specific process is as follows:

[0085] Weigh 50 mg of Ag-Co / CoO@MCS and 0.192 g of furfural and place them in a reaction vessel. At the same time, add 0.1 g of dodecane as an internal standard, then add 10 mL of ethanol as a solvent. Charge 0.5 MPa of hydrogen into the reaction vessel to displace the residual air in the reaction vessel, repeat this 5 times, then charge 1 MPa of hydrogen. Then, use a heating jacket to heat the reaction vessel to 110 °C, and stir and react at a rotation speed of 800 rpm for 1 h. After the reaction is completed, take out the reaction vessel from the heating jacket, let it cool to room temperature and then release the pressure. Then, use a filter membrane to separate the solid and liquid in the liquid in the reaction vessel. The obtained liquid is a mixed liquid containing 2-methylfuran.

[0086] Analyze the liquid obtained in Application Example 2 by gas chromatography, calculate the conversion rate and selectivity, and the results are shown in Figure 7 。

[0087] Application Example 3

[0088] The Pd-Co / CoO@MCS prepared in Example 3 was used in the hydrogenation of furfural to 2-methylfuran. The specific process was as follows:

[0089] Weighed 50 mg of Pd-Co / CoO@MCS and 0.192 g of furfural and placed them in a reaction kettle. At the same time, 0.1 g of dodecane was added as an internal standard, and then 10 mL of ethanol was added as a solvent. 0.5 MPa of hydrogen was charged into the reaction kettle to displace the residual air in the reaction kettle, and this was repeated 5 times. Then, 1 MPa of hydrogen was charged, and then the reaction kettle was heated to 110 °C using a heating jacket and stirred at 800 rpm for 1 h. After the reaction ended, the reaction kettle was taken out of the heating jacket, cooled to room temperature, and the pressure was released. Then, the liquid in the reaction kettle was separated by solid-liquid separation using a filter membrane, and the obtained liquid was a mixed liquid containing 2-methylfuran.

[0090] The liquid obtained in Application Example 3 was analyzed by gas chromatography to calculate the conversion rate and selectivity. The results are shown in Figure 7 .

[0091] Application Example 4

[0092] The Ru-Co / CoO@MCS prepared in Example 4 was used in the production of 2-methylfuran from furfural. The specific process was as follows:

[0093] Weighed 50 mg of Ru-Co / CoO@MCS and 0.192 g of furfural and placed them in a reaction kettle. At the same time, 0.1 g of dodecane was added as an internal standard, and then 10 mL of ethanol was added as a solvent. 0.5 MPa of hydrogen was charged into the reaction kettle to displace the residual air in the reaction kettle, and this was repeated 5 times. Then, 1 MPa of hydrogen was charged, and then the reaction kettle was heated to 110 °C using a heating jacket and stirred at 800 rpm for 1 h. After the reaction ended, the reaction kettle was taken out of the heating jacket, cooled to room temperature, and the pressure was released. Then, the liquid in the reaction kettle was separated by solid-liquid separation using a filter membrane, and the obtained liquid was a mixed liquid containing 2-methylfuran.

[0094] The liquid obtained in Application Example 4 was analyzed by gas chromatography to calculate the conversion rate and selectivity. The results are shown in Figure 7 .

[0095] Figure 7 It is a performance diagram of the micro-porous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposites prepared in Examples 2-4 for the catalytic hydrogenation of the biomass platform molecule furfural to 2-methylfuran. As Figure 7 can be seen, the conversion rates of the nanocomposites to furfural are all above 80%, and their selectivities are also all greater than 90%. This indicates that the nanocomposites provided by the present invention have excellent catalytic activity under mild conditions.

[0096] Comparative Application Example 1

[0097] The composite material prepared in Comparative Example 1 was used in the production of 2-methylfuran from furfural. The specific process was as follows:

[0098] Weigh 50 mg of the composite material prepared in Comparative Example 1 and place it in different reaction vessels respectively. Then, add 0.192 g of furfural to each reaction vessel, add 0.1 g of dodecane as an internal standard, and then add 10 mL of ethanol as a solvent. Charge 0.5 MPa of hydrogen into each reaction vessel to displace the residual air in the reaction vessel, repeat 5 times, then charge 1 MPa of hydrogen, and then use a heating jacket to heat each reaction vessel to 70 - 100 °C and stir and react at a speed of 800 rpm for 1 h. After the reaction is completed, take out the reaction vessel from the heating jacket, let it cool to room temperature and then release the pressure. Then, separate the solid and liquid in the reaction vessel using a filter membrane. The resulting liquid is a mixed solution containing 2-methylfuran.

[0099] The liquid obtained in Comparative Application Example 1 was analyzed using gas chromatography, and the conversion rate and selectivity were calculated. The results are shown in Figure 8 .

[0100] Figure 8 It is a performance graph of the composite material prepared in Comparative Example 1 for the production of 2-methylfuran from furfural. As can be seen from Figure 8 , the nano-composite material in Comparative Example 1 had low selectivity for the production of 2-methylfuran from furfural at a relatively low temperature, and the conversion rate of furfural was also low.

[0101] Comparative Application Examples 2 - 7

[0102] The composite materials prepared in Comparative Examples 2 - 7 were used in the production of 2-methylfuran from furfural. The specific process was as follows:

[0103] Weigh 50 mg of the composite materials prepared in Comparative Examples 2 - 7 and place them in different reaction vessels respectively. Then, add 0.192 g of furfural to each reaction vessel, add 0.1 g of dodecane as an internal standard, and then add 10 mL of ethanol as a solvent. Charge 0.5 MPa of hydrogen into each reaction vessel to displace the residual air in the reaction vessel, repeat 5 times, then charge 1 MPa of hydrogen, and then use a heating jacket to heat each reaction vessel to 70 - 100 °C and stir and react at a speed of 800 rpm for 1 h. After the reaction is completed, take out the reaction vessel from the heating jacket, let it cool to room temperature and then release the pressure. Then, separate the solid and liquid in the reaction vessel using a filter membrane. The resulting liquid is a mixed solution containing 2-methylfuran.

[0104] The liquids obtained in Comparative Application Examples 2 - 7 were analyzed using gas chromatography, and the conversion rate and selectivity were calculated. The results are shown in Table 1.

[0105] Table 1

[0106]

[0107] As can be seen from Table 1, in Comparative Examples 3-4, the temperature of the displacement reaction was changed, and in Comparative Examples 5-6, the time of the displacement reaction was changed. When the obtained composite materials were used in the production of 2-methylfuran from furfural, the conversion rate and selectivity both showed varying degrees of decrease; it shows that by controlling the temperature and time of the displacement reaction, the present invention obtains a composite material with excellent catalytic hydrogenolysis activity and selectivity. After the displacement reaction in Comparative Example 7, calcination and reduction were continued. When the obtained composite material was used in the production of 2-methylfuran from furfural, both the conversion rate and selectivity decreased significantly, indicating that when the micropores were damaged, the confinement effect failed, resulting in no formation of 2-methylfuran in the product, indicating that the micropore confinement plays a crucial role in the selectivity of 2-methylfuran.

[0108] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material, characterized in that: The microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material comprises microporous carbon spheres, cobalt, cobalt oxide and noble metals; the cobalt is partially coated by the noble metal, the uncoated cobalt forms cobalt oxide, the cobalt, cobalt oxide and noble metal form a cobalt / cobalt oxide core-noble metal shell, and the cobalt / cobalt oxide core-noble metal shell is confined in the microporous carbon spheres; the content of noble metal in the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material is 5-8wt.%; the content of cobalt in the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material is 5-8wt.%; the pore size of the microporous carbon spheres is 0.7-1.5nm, the particle size of the cobalt is 8-15nm, and the coverage rate of the partial coating is 50-80%.

2. The microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material according to claim 1, characterized in that: The noble metal includes one of Ag, Pt, Pd and Ru.

3. The method for preparing the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material according to any one of claims 1 to 2, characterized in that: The method comprises the following steps: placing a microporous carbon sphere confined cobalt composite material and ethanol in a closed reaction kettle, introducing hydrogen for pre-reduction, introducing nitrogen into the closed reaction kettle to change the hydrogen atmosphere in the kettle into nitrogen, adding a noble metal precursor aqueous solution and using a circulating vacuum pump to maintain a negative pressure in the kettle for a replacement reaction, centrifuging after the reaction is completed, and vacuum drying to finally obtain the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material.

4. The preparation method according to claim 3, characterized in that: The temperature of the replacement reaction is ≤25°C, the time is 48h, and the pressure is -0.1MPa.

5. The preparation method according to claim 3, characterized in that: The dosage ratio of the microporous carbon sphere confined cobalt composite material, ethanol and the noble metal precursor aqueous solution is 0.1g:10mL:(1.57-2.71)mL; the concentration of the noble metal precursor aqueous solution is 1g / 100mL.

6. Use of the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material as claimed in any one of claims 1 to 2 in catalyzing the hydrogenolysis of biomass platform molecules.

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