A microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material and its preparation method and application

Abstract

The present invention discloses a microporous carbon sphere-confined cobalt / cobalt oxide core-precious metal shell nanocomposite material and its preparation method and application, belonging to the field of catalyst technology. The present invention uses non-precious metal cobalt and cobalt oxide as acidic active sites and precious metals as hydrogen dissociation active sites. A replacement reaction is used to deposit precious metals on the surface of the cobalt / cobalt oxide core to form a precious metal shell. On the one hand, the catalytic effect of precious metals can be fully utilized. On the other hand, non-precious metal cobalt is used to replace part of the precious metal, which significantly reduces the cost of the catalyst. The formed cobalt / cobalt oxide core-precious metal shell is confined in the microporous carbon spheres. The confinement of the microporous carbon spheres increases the stability of the catalyst and reduces the loss of cobalt and precious metals. Finally, a microporous carbon sphere-confined cobalt / cobalt oxide core-precious metal shell nanocomposite material with excellent catalytic hydrogenolysis activity, selectivity and stability for upgrading molecular hydrogenolysis of biomass platforms is obtained.

Description

Technical Field

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

[0002] Since their discovery, fossil fuels have been a core driving force for global economic progress, industrialization, and technological innovation. However, their non-renewable nature and environmental damage are also significant. Biomass, as a low-cost, abundant, renewable resource, is an ideal alternative to fossil resources and has garnered widespread attention in recent years. Many furan derivatives, such as 5-hydroxymethylfuran (5-HMF), furfural, and 5-methylfurfural (5-MF), can be efficiently obtained from cellulose and hemicellulose and are the main components of biomass. These furan derivatives serve as platform molecules for the production of other value-added chemicals. High-value-added chemicals and organic synthesis intermediates can be prepared through hydrogenation, deoxygenation, and hydrolysis of biomass raw materials.

[0003] Improving the hydrodeoxygenation activity and selectivity of target products in biomass raw materials is both a key and challenging task. Reported studies have primarily used metal oxides or activated carbon-supported metal elements as catalysts. Precious metal nanoparticles inherently possess excellent properties such as redox catalysis, photosensitivity, and electrical conductivity. Consequently, highly efficient precious metal catalysts such as Pd, Pt, and Ir have been developed for the hydrogenolysis of biomass platform molecules. However, limited by precious metal reserves, cost, and stability, the application cost of precious metal catalysts remains high, restricting their application.

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

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

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

[0007] The invention provides a microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material, wherein the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material comprises microporous carbon spheres, cobalt, cobalt oxide and noble metal; the cobalt is partially coated with 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 diameter of the microporous carbon spheres is 0.7-1.5nm, the particle diameter of the cobalt is 8-15nm, and the coverage rate of the partial coating is 50-80%.

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

[0009] The present invention provides a method for preparing a microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material described in the above technical solution, comprising the following steps: placing the microporous carbon sphere confined cobalt composite material and ethanol in a closed reactor, introducing hydrogen for pre-reduction, then introducing nitrogen into the closed reactor to change the hydrogen atmosphere in the reactor 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 reactor 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.

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

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

[0012] The present invention also provides the use of the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material described in the above technical solution in catalyzing the hydrogenolysis of biomass platform molecules.

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

[0014] The present invention uses non-precious metal cobalt and cobalt oxide as acidic active sites and precious metals as hydrogen dissociation active sites, and utilizes a replacement reaction to deposit precious metals on the surface of a cobalt / cobalt oxide core to form a precious metal shell. On the one hand, the catalytic effect of the precious metal can be fully exerted, and on the other hand, non-precious metal cobalt is used to replace part of the precious metal, which significantly reduces the cost of the catalyst. In addition, the formed cobalt / cobalt oxide core-precious metal shell is confined in microporous carbon spheres. The confinement of the microporous carbon spheres increases the stability of the catalyst and reduces the loss of cobalt and precious metals. Ultimately, a microporous carbon sphere-confined cobalt / cobalt oxide core-precious metal shell nanocomposite material with excellent catalytic hydrogenolysis activity, selectivity and stability for molecular hydrogenolysis upgrading of biomass platforms is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying 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 diagram of Pt-Co / CoO@MCS prepared in Example 1 of the present invention;

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

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

[0021] Figure 6 This is a performance diagram of the Pt-Co / CoO@MCS prepared in Example 1 of the present invention for furfural to 2-methylfuran;

[0022] Figure 7 Performance diagram of the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite prepared in Examples 2 to 4 of the present invention for use in furfural to 2-methylfuran;

[0023] Figure 8 This is a performance diagram of the composite material prepared in Comparative Example 1 for use in preparing 2-methylfuran from furfural. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] An embodiment of the present invention provides a microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material, wherein the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material comprises microporous carbon spheres, cobalt, cobalt oxide and noble metal; the cobalt is partially coated with 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 sphere; 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 sphere 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%. The present invention combines microporous carbon spheres, cobalt, cobalt oxide and precious metals to give full play to the synergistic effect of the microporous carbon spheres and cobalt, while limiting the pore sizes of the microporous carbon spheres and cobalt, reducing the loss of cobalt and precious metals, and ensuring the catalytic hydrogenolysis activity of the nanocomposite material under the condition of a low total content of cobalt and precious metals.

[0027] In a preferred embodiment, the noble metal comprises one of Ag, Pt, Pd, and Ru. The noble metal in the present invention serves as a hydrogen dissociation active site, and its use as a shell to coat the cobalt / cobalt oxide core has the advantages of saving the amount of noble metal and enhancing the catalyst's ability to hydrogenolyze biomass platform molecules.

[0028] The present invention provides a method for preparing a microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material described in the above technical solution, comprising the following steps: placing the microporous carbon sphere confined cobalt composite material and ethanol in a closed reactor, introducing hydrogen for pre-reduction, then introducing nitrogen into the closed reactor to change the hydrogen atmosphere in the reactor 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 reactor 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.

[0029] The present invention places a microporous carbon sphere confined cobalt composite material and ethanol in a closed reactor and introduces hydrogen for pre-reduction to remove an oxide layer on the surface of the cobalt core, thereby keeping the surface of the cobalt core as elemental cobalt; nitrogen is introduced into the closed reactor to maintain a negative pressure in the reactor, and vacuum-assisted impregnation is utilized to promote an aqueous solution of a noble metal precursor to enter the pores of the microporous carbon, thereby causing a replacement reaction 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, while the uncoated cobalt is easily oxidized due to its very small particle size and large specific surface area, and is oxidized in air to form cobalt oxide, thereby obtaining a microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material.

[0030] In a preferred embodiment, the pre-reduction temperature 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 replacement reaction is ≤25°C, more preferably 10-25°C; the replacement reaction time is 48 hours, the pressure is -0.1 MPa, and the atmosphere is nitrogen. In the present invention, the temperature and time of the replacement reaction have a significant impact on the formation of the noble metal shell. If the reaction temperature is too high, the noble metal in the noble metal precursor aqueous solution will easily form a noble metal sol. If the reaction temperature is too low, the replacement will fail. If the reaction time is too long, the noble metal shell will be thick or uneven in thickness. If the reaction time is too short, the noble metal coverage will be low, and an effective noble metal shell cannot be formed.

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

[0033] In a preferred embodiment, the preparation method of the microporous carbon sphere confined cobalt composite material includes the following steps: mixing a cobalt precursor, trimesic acid and a solvent, and then performing 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 ratio of the cobalt precursor, trimesic acid, and 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; and the mixing time is 60 minutes.

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

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

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

[0039] In a preferred embodiment, the reduction is specifically performed by heating the sample to 500° C. at a heating rate of 5° C. / min in a 5% H 2 / Ar mixed gas and keeping the temperature for 2 hours.

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

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

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

[0043] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0044] Example 1

[0045] A microporous carbon sphere-confined cobalt / cobalt oxide core-noble metal shell nanocomposite material comprises microporous carbon spheres, Co, CoO, and Pt; Co is partially coated with Pt, 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; the Pt content and Co content in the composite material are 8 wt.%, 8 wt.%, the pore diameter of the microporous carbon spheres is 1.2 nm, the particle size of Co is 9 nm, and the Pt coverage is 60-65%.

[0046] The preparation method of 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 and dissolve them in 60 mL of ethanol and stir for 60 min to obtain solution A; the obtained solution A is placed in a hydrothermal reactor and hydrothermally synthesized at 150 °C for 12 h, cooled to room temperature, and the product is separated and washed with ethanol 4 times, and dried 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, heated to 650°C in an argon atmosphere at a heating rate of 5°C / min and kept warm 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, 10 mL of a 4 mol / L nitric acid solution was added, and the mixture was stirred at 55°C for 2 h. After stirring, the mixture was washed with water and ethanol three times respectively, and dried at 60°C in a vacuum to obtain an intermediate product; the intermediate product was placed in a tubular furnace, and heated to 500°C at a heating rate of 5°C / min in a 5% H2 / Ar mixed gas, and kept warm for 2 h. The mixture was 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 reactor, hydrogen was introduced, and pre-reduction was carried out under the reaction conditions of 1.0 MPa hydrogen and 120°C for 5 h. Then, nitrogen was introduced into the closed reactor to change the hydrogen atmosphere in the reactor to nitrogen. 2.71 mL of a 1 g / 100 mL aqueous solution of chloroplatinic acid was added and a circulating vacuum pump was used to maintain the pressure in the reactor at -0.1 MPa. Then, the mixture was stirred and replaced at 10°C for 48 h. After the stirring was completed, it was washed once with ethanol and dried in a vacuum at 50°C to obtain a microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material (Pt-Co / CoO@MCS) with a Co content of 8 wt.% and a Pt content of 8 wt.%.

[0051] Figure 1 The XRD patterns of Pt-Co / CoO@MCS prepared in Example 1 and Co@MCS in step (3) of Example 1 are shown in FIG. Figure 1 It can be seen that the peak at 44° is that of Co, the peak at 39.6° is that of Pt, and the peak of CoO is not visible, which may be due to the low content. By comparing the XRD curve with the standard card, it can be seen that after replacement, the coverage of Pt is relatively high, and the peak intensity of Co is relatively low, indicating that Pt is on the surface of Co. X-rays first pass through Pt and then reach Co. The Pt peak in the figure is slightly offset, which indirectly proves the metallic interaction between them.

[0052] Figure 2 This is the HRTEM image of Pt-Co / CoO@MCS prepared in Example 1 of the present invention. Figure 2 It can be seen that the morphology of the nanocomposite material is an independent sphere with many holes on the surface. The diameter of the sphere is about 2 μm.

[0053] Figure 3This is a mapping diagram of the Pt-Co / CoO@MCS prepared in Example 1 of the present invention; the figure shows the distribution of Pt, C, O, and Co, respectively. The distribution of platinum and cobalt is relatively uniform, consistent with the spherical structure of a cobalt / cobalt oxide core and a precious metal shell.

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

[0055] Figure 5 Schematic diagram of the structure of Pt-Co / CoO@MCS prepared in Example 1 of the present invention. Figure 5 It can be seen that the 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 by a silver nitrate aqueous solution of the same concentration and volume of 1.57 mL to obtain Ag-Co / CoO@MCS with a Co content of 8 wt.% and an Ag content of 8 wt.%.

[0058] Example 3

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

[0060] Example 4

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

[0062] Comparative Example 1

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

[0064] Comparative Example 2

[0065] (1) 1.04 g of trimesic acid was weighed and dissolved in 60 mL of ethanol and stirred for 60 min. The mixture was then placed in a hydrothermal reactor and subjected to hydrothermal synthesis at 150°C for 12 h. The mixture was cooled to room temperature and dried at 80°C to remove the ethanol.

[0066] (2) The material obtained in step (1) was placed in a tube furnace, heated to 650°C at a heating rate of 5°C / min in an argon atmosphere, and kept at this temperature for 2 h to obtain MC nanoparticles.

[0067] (3) 0.2 g of the MC nanoparticles obtained in step (2) was placed in a beaker, 10 mL of a 4 mol / L nitric acid solution was added, and the mixture was stirred at 55°C for 2 h. After stirring, the mixture was washed with water and ethanol three times, and dried at 60°C in a vacuum to obtain an intermediate product. The intermediate product was placed in a tubular furnace, heated to 500°C at a heating rate of 5°C / min in a 5% H2 / Ar mixed gas, and kept warm for 2 h. The mixture was naturally cooled to obtain MCS.

[0068] Comparative Example 3

[0069] The difference from Example 1 is that in step (4), the replacement is carried out with stirring at 50° C. for 48 h, 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), the replacement is carried out with stirring at 5° C. for 48 h, 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), the replacement is carried out with stirring at 10° C. for 40 h, 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), the replacement is carried out with stirring at 10° C. for 60 h, 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), Pt-Co / CoO@MCS is placed in a muffle furnace for calcination at 600°C for 2 h, and then placed in a tube furnace for reduction at 400°C for 3 h, with a heating rate of 5°C / min and an atmosphere of 10% H2 / Ar.

[0078] Application Example 1

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

[0080] 50mg of Pt-Co / CoO@MCS and 0.192g of furfural were weighed and placed in separate reactors. 10mL of ethanol was then added to each reactor as a solvent, along with 0.1g of dodecane as an internal standard. Each reactor was then filled with 0.5MPa of hydrogen to displace any remaining air. This process was repeated five times, followed by a 1MPa charge of hydrogen. Each reactor was then heated to 70-110°C using a heating mantle and stirred at 800rpm for 1h. After the reaction was complete, the reactors were removed from the heating mantles, cooled to room temperature, and the pressure was vented. The liquid in the reactors was then filtered for solid-liquid separation, resulting in a mixture containing 2-methylfuran.

[0081] The liquid obtained in Application Example 1 was analyzed by gas chromatography to calculate the conversion rate and selectivity. The results are shown in Figure 6 .

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

[0083] Application Example 2

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

[0085] 50mg of Ag-Co / CoO@MCS and 0.192g of furfural were placed in a reactor. 0.1g of dodecane was added as an internal standard, followed by 10mL of ethanol as the solvent. The reactor was then filled with 0.5MPa of hydrogen to displace any remaining air. This process was repeated five times, followed by 1MPa of hydrogen. The reactor was then heated to 110°C using a heating mantle and stirred at 800rpm for 1h. After the reaction was complete, the reactor was removed from the heating mantle, cooled to room temperature, and the pressure was vented. The liquid in the reactor was then filtered for solid-liquid separation, resulting in a mixture containing 2-methylfuran.

[0086] The liquid obtained in Application Example 2 was analyzed by gas chromatography to calculate the conversion rate and selectivity. 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 produce 2-methylfuran. The specific process was as follows:

[0089] 50mg of Pd-Co / CoO@MCS and 0.192g of furfural were placed in a reactor. 0.1g of dodecane was added as an internal standard, followed by 10mL of ethanol as the solvent. The reactor was then filled with 0.5MPa of hydrogen to displace any remaining air. This process was repeated five times, followed by 1MPa of hydrogen. The reactor was then heated to 110°C using a heating mantle and stirred at 800rpm for 1h. After the reaction was complete, the reactor was removed from the heating mantle, cooled to room temperature, and the pressure was vented. The liquid in the reactor was then filtered for solid-liquid separation, resulting in a mixture 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] 50mg of Ru-Co / CoO@MCS and 0.192g of furfural were placed in a reactor. 0.1g of dodecane was added as an internal standard, followed by 10mL of ethanol as the solvent. The reactor was then filled with 0.5MPa of hydrogen to displace any remaining air. This process was repeated five times, followed by a 1MPa charge of hydrogen. The reactor was then heated to 110°C using a heating mantle and stirred at 800rpm for 1h. After the reaction was complete, the reactor was removed from the heating mantle, cooled to room temperature, and the pressure was vented. The liquid in the reactor was then filtered for solid-liquid separation, resulting in a mixture 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 The performance diagram of the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite prepared in Examples 2 to 4 for catalyzing the hydrogenation of biomass platform molecule furfural to 2-methylfuran. Figure 7 It can be seen that the conversion rate of furfural by the nanocomposite materials is above 80%, and the selectivity is also above 90%, indicating that the nanocomposite materials 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 preparation of 2-methylfuran from furfural, and the specific process was as follows:

[0098] 50 mg of the composite material prepared in Comparative Example 1 was weighed and placed in different reactors. 0.192 g of furfural was then added to each reactor, along with 0.1 g of dodecane as an internal standard. 10 mL of ethanol was then added as a solvent. 0.5 MPa of hydrogen was then introduced into each reactor to displace the residual air in the reactor. This was repeated five times, followed by 1 MPa of hydrogen. Each reactor was then heated to 70-100 ° C using a heating jacket and stirred at 800 rpm for 1 hour. After the reaction was completed, the reactor was removed from the heating jacket, cooled to room temperature, and the pressure was released. The liquid in the reactor was then filtered for solid-liquid separation. The resulting liquid was a mixed solution containing 2-methylfuran.

[0099] The liquid obtained in Comparative Application Example 1 was analyzed by gas chromatography to calculate the conversion rate and selectivity. The results are shown in Figure 8 .

[0100] Figure 8 The performance diagram of the composite material prepared in Comparative Example 1 for furfural to 2-methylfuran. Figure 8 It can be seen that the nanocomposite material of Comparative Example 1 has low selectivity for furfural to 2-methylfuran at relatively low temperature, and the conversion rate of furfural is also low.

[0101] Comparative Application Examples 2-7

[0102] The composite material prepared in Comparative Examples 2-7 was used in the preparation of 2-methylfuran from furfural, and the specific process was as follows:

[0103] 50 mg of the composite materials prepared in Comparative Examples 2-7 were respectively weighed and placed in different reactors. 0.192 g of furfural was then added to each reactor, along with 0.1 g of dodecane as an internal standard. 10 mL of ethanol was then added as a solvent. 0.5 MPa of hydrogen was then introduced into each reactor to displace the residual air in the reactor. This was repeated five times, followed by 1 MPa of hydrogen. Each reactor was then heated to 70-100 ° C using a heating jacket and stirred at 800 rpm for 1 hour. After the reaction was completed, the reactor was removed from the heating jacket, cooled to room temperature, and the pressure was released. The liquid in the reactor was then separated into a solid-liquid state using a filter membrane. The resulting liquid was a mixed solution containing 2-methylfuran.

[0104] The liquid obtained in Comparative Application Examples 2-7 was analyzed by 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, Comparative Examples 3-4 change the temperature of the replacement reaction, and Comparative Examples 5-6 change the time of the replacement reaction. When the composite materials are used to prepare 2-methylfuran from furfural, the conversion rate and selectivity show varying degrees of reduction; this shows that the present invention obtains a composite material with excellent catalytic hydrogenolysis activity and selectivity by controlling the temperature and time of the replacement reaction. Comparative Example 7 continues to calcine and reduce after the replacement reaction is completed. When the composite material is used to prepare 2-methylfuran from furfural, the conversion rate and selectivity are greatly reduced, indicating that when the micropores are destroyed, the confinement effect fails, resulting in the absence of 2-methylfuran in the product, indicating that micropore confinement plays a crucial role in the selectivity of 2-methylfuran.

[0108] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing 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 is composed of microporous carbon spheres, Co, CoO, and a noble metal; the Co is partially coated with the noble metal, the uncoated Co forms CoO, the Co, CoO, and the noble metal form a Co / CoO core-noble metal shell, and the Co / CoO core-noble metal shell is confined in the microporous carbon spheres; the noble metal content in the composite material is 8 wt.%, the Co content is 8 wt.%, the microporous carbon sphere pore diameter is 1.2 nm, the Co particle diameter is 9 nm, and the noble metal coverage is 60-65%; the noble metal is Ag or Pt; The preparation method of the microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material is as follows: (1) Weigh 1.04 g of cobalt nitrate hexahydrate and 1.04 g of trimesic acid and dissolve them in 60 mL of ethanol and stir for 60 min to obtain solution A; place the obtained solution A in a hydrothermal reactor and perform hydrothermal synthesis at 150°C for 12 h, cool to room temperature, separate the product, wash it with ethanol four times, and dry it at 80°C to obtain the Co-MOF precursor material; (2) placing the Co-MOF precursor material obtained in step (1) in a tube furnace, heating it to 650° C. at a heating rate of 5° C. / min in an argon atmosphere, and keeping the temperature for 2 h to obtain Co@MC nanoparticles with a Co content of 80 wt.%; (3) 0.2 g of the Co@MC nanoparticles obtained in step (2) was placed in a beaker, 10 mL of a 4 mol / L nitric acid solution was added, and the mixture was stirred at 55°C for 2 h. After stirring, the mixture was washed with water and ethanol three times, and dried at 60°C in a vacuum oven to obtain an intermediate product. The intermediate product was placed in a tube furnace, heated to 500°C at a heating rate of 5°C / min in a 5% H2 / Ar mixture, and kept warm for 2 h. The mixture was then cooled naturally to obtain Co@MCS with a Co content of 16 wt.%. (4) 0.1 g of the Co@MCS obtained in step (3) and 10 mL of ethanol were placed in a closed reactor, hydrogen was introduced, and pre-reduction was carried out under the reaction conditions of 1.0 MPa hydrogen and 120°C for 5 h. Then, nitrogen was introduced into the closed reactor to change the hydrogen atmosphere in the reactor to nitrogen. A noble metal precursor aqueous solution with a concentration of 1 g / 100 mL was added and a circulating vacuum pump was used to maintain the pressure in the reactor at -0.1 MPa. Then, the mixture was stirred and replaced at 10°C for 48 h. After the stirring was completed, it was washed once with ethanol and dried at 50°C in a vacuum to obtain a microporous carbon sphere confined cobalt / cobalt oxide core-noble metal shell nanocomposite material with a Co content of 8 wt.% and a noble metal content of 8 wt.%. The noble metal precursor aqueous solution was a chloroplatinic acid aqueous solution or a silver nitrate aqueous solution. The amount of the noble metal precursor aqueous solution was 1.57~2.71 mL.

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