Preparation method and application of carbon nanocage-supported indium oxide catalyst

Abstract

The present invention relates to a preparation method and application of a carbon nanocage-supported indium oxide catalyst, belonging to the technical field of catalyst preparation. The present invention combines carbon nanocages with excellent photothermal performance and high specific surface area with indium oxide semiconductor materials with good photochemical properties and excellent intrinsic catalytic performance. The prepared carbon nanocage-supported indium oxide catalyst has the advantages of efficient full-spectrum utilization, excellent photothermal performance and a high number of active sites. The carbon nanocage-supported indium oxide catalyst of the present invention has the advantages of efficient full-spectrum utilization, excellent photothermal performance and a high number of active sites. ‑2 Under the illumination conditions of 100 nm, the production rate of methanol from catalytic carbon dioxide hydrogenation reached 1220.6 μmol / gh, and the methanol selectivity was as high as 96%, providing a new idea for the construction of high-efficiency photocatalysts.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a preparation method and application of a carbon nanocage-supported indium oxide catalyst. Background Art

[0002] Liquid sunlight methanol synthesis technology is of great significance for the development of clean energy and mitigation of the "greenhouse effect", and has become a research frontier in the fields of materials, catalysis, and energy. Compared with gaseous energy, methanol is more stable and easy to store and transport, making it one of the best media for storing hydrogen. It can also be used as high-value-added chemicals and fuels such as light olefins and aromatics, promoting the development of green and clean energy. The ideal photocatalytic carbon dioxide hydrogenation system to produce methanol uses only sunlight as the sole energy source to drive the reaction. However, traditional photochemical catalysts are generally only responsive to ultraviolet and a small portion of the visible light band. Limited by their low light utilization efficiency, the efficiency of photocatalytic carbon dioxide hydrogenation to produce methanol is still far below the actual application requirements.

[0003] Recently, researchers have proposed the concept of photothermal catalytic CO2 hydrogenation to methanol. By broadening the solar spectral response range (part of the visible and infrared bands), the catalyst's photothermal effect converts light energy into heat, thereby driving the catalytic reaction. This reaction pathway has the potential to be driven by pure sunlight, thereby replacing traditional heat sources and reducing fossil energy use and carbon emissions. Professor Ozin's research group at the University of Toronto, Canada, has reported a new "black indium oxide" photothermal catalyst, and strategies for modifying its methanol catalytic activity and selectivity have emerged. However, photothermal catalysis is still essentially thermally activated, and its high reaction temperature is thermodynamically unfavorable for methanol formation (CO2 hydrogenation to methanol is an exothermic reaction). The harsh conditions also affect the catalyst's lifespan. Therefore, photothermal catalytic CO2 hydrogenation to methanol has the potential to be fully solar-driven, but it is still limited by the mismatch between thermodynamics and kinetics, and the catalyst's activity, selectivity, and stability are in urgent need of improvement.

[0004] The development of photothermal / photochemical synergistic catalytic systems enables efficient utilization of the entire solar spectrum, providing a new path for building efficient photo-chemical energy conversion systems. Generally speaking, photochemical effects primarily utilize short-wavelength sunlight, while photothermal effects primarily utilize long-wavelength sunlight, but it is often difficult to efficiently utilize both simultaneously within the same material system.

[0005] In view of the above situation, it is necessary to develop a photothermal / photochemical synergistic catalyst that can efficiently utilize the entire solar spectrum, so as to achieve effective synergy between the photochemical effect in the ultraviolet band and the photothermal effect in the visible-infrared band, greatly improve the utilization efficiency of light, and realize efficient photo-chemical energy conversion, thereby realizing the use of only sunlight as the only energy to drive the catalytic hydrogenation of carbon dioxide to produce methanol. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a carbon nanocage-supported indium oxide catalyst and its application in catalytic carbon dioxide hydrogenation to methanol. By selecting a carbon nanocage carrier with excellent photothermal performance, high specific surface area, and a multi-level pore structure and combining it with an indium oxide semiconductor material with good photochemical properties and excellent intrinsic catalytic performance, the prepared carbon nanocage-supported indium oxide catalyst has the advantages of excellent photothermal performance, efficient utilization of the entire spectrum, and a high number of active sites. At the same time, the effective synergy of the photochemical effect in the ultraviolet band and the photothermal effect in the visible-infrared band can achieve efficient photo-chemical energy conversion, laying the foundation for the catalytic carbon dioxide hydrogenation to methanol under complete sunlight drive.

[0007] The first object of the present invention is to provide a method for preparing a carbon nanocage-supported indium oxide catalyst, comprising the following steps:

[0008] S1: dissolving the carbon nanocage and the indium salt compound in a solvent and mixing them uniformly to obtain a mixed solution;

[0009] S2: adding an alkaline compound to the mixed solution for heating reaction to obtain carbon nanocage-supported indium hydroxide powder;

[0010] S3: calcining the carbon nanocage-supported indium hydroxide powder in an inert atmosphere to obtain the carbon nanocage-supported indium oxide catalyst.

[0011] Furthermore, in step S1, the mass ratio of the carbon nanocage to the indium salt compound is 1:(5-10).

[0012] Furthermore, the indium salt compound in step S1 is selected from one or more of indium nitrate, indium chloride and indium sulfate.

[0013] Furthermore, the solvent in step S1 is deionized water or ethanol.

[0014] Furthermore, the alkaline compound in step S2 is ammonia water or sodium hydroxide.

[0015] Furthermore, the heating temperature in step S2 is 60-100° C., and the heating time is 10-30 minutes.

[0016] Furthermore, the gas of the inert atmosphere in step S3 is argon, the temperature of the inert atmosphere calcination is 200-400° C., and the time of the inert atmosphere calcination is 1-3 hours.

[0017] Furthermore, step S3 further includes a step of calcining in a hydrogen atmosphere.

[0018] Furthermore, the calcination temperature in the hydrogen atmosphere is 200-400° C., and the calcination time in the hydrogen atmosphere is no more than 2 hours.

[0019] The second object of the present invention is to provide a carbon nanocage-supported indium oxide catalyst prepared by the above preparation method.

[0020] Furthermore, the indium oxide is loaded on the surface of the carbon nanocage or between adjacent carbon nanocages.

[0021] Furthermore, the loading amount of the indium oxide is 20-40%.

[0022] Furthermore, the carbon nanocage-supported indium oxide catalyst has a reflectivity of 6-12% at a wavelength of 200-2300 nm.

[0023] The third object of the present invention is to provide an application of a carbon nanocage-supported indium oxide catalyst in catalyzing the hydrogenation of carbon dioxide to produce methanol, the specific steps comprising:

[0024] The obtained carbon nanocage-loaded indium oxide catalyst is ultrasonically dispersed in ethanol and evenly drop-coated on glass fiber filter paper. It is then transferred to a stainless steel stationary phase or mobile phase reactor, and carbon dioxide, hydrogen and nitrogen are introduced to react and generate methanol.

[0025] Furthermore, the reaction temperature is 280°C, the reaction pressure is 2-2.8 MPa, the reaction light wavelength is 300-2500 nm, and the reaction light intensity is 0-3 W·cm -2 .

[0026] In summary, compared with the prior art, the advantages of the present invention are:

[0027] 1. The present invention uses carbon nanocages as carriers, utilizing their good light absorption ability in the visible and infrared bands, combined with the strong absorption of indium oxide in the ultraviolet band, to achieve efficient utilization of the entire solar spectrum.

[0028] 2. The present invention utilizes the structural advantages of the multi-level pore structure and large specific surface area of ​​carbon nanocages to improve the dispersion of indium oxide and increase the number of reactive sites, thereby enhancing catalytic activity.

[0029] 3. The present invention utilizes the excellent photothermal conversion performance of carbon nanocages to compensate for the insufficient photothermal activity of indium oxide. The two complement each other perfectly, thereby realizing photothermal / photochemical synergistic catalysis of carbon dioxide hydrogenation to produce methanol.

[0030] 4. The present invention adopts photothermal / photochemical synergistic catalysis as a new strategy for producing methanol from carbon dioxide hydrogenation, which is expected to achieve efficient conversion of solar energy to chemical energy under mild conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0032] Figure 1 The powder X-ray crystal diffraction pattern of catalyst a prepared in Example 1 of the present invention is shown.

[0033] Figure 2 This is a transmission electron microscope image of catalyst a prepared in Example 1 of the present invention.

[0034] Figure 3 This is the UV-visible diffuse reflectance spectrum of catalyst a prepared in Example 1 of the present invention.

[0035] Figure 4 The powder X-ray crystal diffraction pattern of catalyst d prepared in Example 4 of the present invention is shown.

[0036] Figure 5 This is a transmission electron microscope image of catalyst d prepared in Example 4 of the present invention.

[0037] Figure 6 This is the UV-visible diffuse reflectance spectrum of catalyst d prepared in Example 4 of the present invention.

[0038] Figure 7 The powder X-ray crystal diffraction pattern of catalyst e prepared in Example 5 of the present invention is shown.

[0039] Figure 8 This is a transmission electron microscope image of catalyst e prepared in Example 5 of the present invention.

[0040] Figure 9 This is the UV-visible diffuse reflectance spectrum of catalyst e prepared in Example 5 of the present invention. DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0042] Example 1

[0043] This specific embodiment provides a preparation method of catalyst a (a carbon nanocage-supported indium oxide catalyst with a loading of 20% and annealed at 400° C. in an argon atmosphere for 3 h), and the specific steps are as follows:

[0044] Step (1): 20 mg of carbon nanocages and 100 mg of indium chloride were dissolved in 12 mL of deionized water, and the mixture was stirred thoroughly with a magnetic stirrer at a stirring rate of 300 rpm. 5 mL of ammonia water, 15 mL of anhydrous ethanol, and 4 mL of deionized water were added thereto while stirring, and the mixture was stirred for 15 minutes to obtain a mixed solution;

[0045] Step (2): The mixed solution was transferred to a round-bottom flask, the round-bottom flask was placed in an oil bath, the liquid surface of the mixed solution was immersed, and the mixture was heated to 80° C. in the oil bath for reaction for 30 min, and then naturally cooled to room temperature in air. After centrifugation, the mixture was washed three times with deionized water, and dried in a vacuum oven for 12 h to obtain a powder material of carbon nanocage-loaded indium hydroxide;

[0046] Step (3): The dried carbon nanocage-loaded indium hydroxide powder material is subjected to high-temperature annealing at a temperature of 400° C. in an argon atmosphere for 3 h to obtain catalyst a.

[0047] The powder X-ray crystal diffraction pattern of catalyst a sample is as follows: Figure 1 As shown by Figure 1 It can be seen that the characteristic diffraction peaks of the sample completely correspond to the standard characteristic diffraction peaks of indium oxide PDF#06-0416 card, indicating that the sample did not undergo phase change or decomposition during the high-temperature annealing process and still maintained the crystalline phase of indium oxide. Figure 2 As shown by Figure 2 It can be seen that under the conditions of annealing at 400℃ in argon atmosphere for 3h, the sample can be clearly observed to have a lighter contrast of carbon nanocages and a darker contrast of indium oxide, which is dispersed on the outer surface of carbon nanocages and in the gaps between adjacent cages, with an average size of about 15nm. The UV-visible diffuse reflectance spectrum of catalyst a sample is shown in the figure below. Figure 3 As shown by Figure 3 It can be seen that the reflectivity of the sample is 6-12% in the spectrum of wavelength 200-2300 nm, indicating that the sample has good light response in the entire spectrum.

[0048] Example 2

[0049] This specific embodiment provides a preparation method of catalyst b (30% loading, carbon nanocage-supported indium oxide catalyst annealed at 400° C. in argon atmosphere for 2 h), the specific steps are as follows:

[0050] Step (1): 20 mg of carbon nanocages and 150 mg of indium nitrate were dissolved in 12 mL of anhydrous ethanol, and the mixture was stirred thoroughly with a magnetic stirrer at a stirring rate of 300 rpm. 5 mL of 1 M NaOH solution, 5 mL of anhydrous ethanol, and 14 mL of deionized water were added thereto while stirring, and stirring was continued for 15 minutes to obtain a mixed solution;

[0051] Step (2): The mixed solution was transferred to a round-bottom flask, and the round-bottom flask was placed in an oil bath pot to immerse the liquid surface of the mixed solution, heated to 60 ° C. in the oil bath for reaction for 20 minutes, and then naturally cooled to room temperature in the air. After centrifugation, it was washed with deionized water three times and dried in a vacuum oven for 12 hours to obtain a powder material of carbon nanocage-loaded indium hydroxide;

[0052] Step (3): The dried carbon nanocage-loaded indium hydroxide powder material is subjected to high-temperature annealing at a temperature of 400° C. in an argon atmosphere for 2 h to obtain catalyst b.

[0053] Example 3

[0054] This specific embodiment provides a preparation method of catalyst C (40% loading, carbon nanocage-supported indium oxide catalyst annealed at 400° C. in argon atmosphere for 1 h), the specific steps are as follows:

[0055] Step (1): 20 mg of carbon nanocages and 200 mg of indium sulfate were dissolved in 12 mL of anhydrous ethanol, and the mixture was stirred thoroughly with a magnetic stirrer at a stirring rate of 300 rpm. 5 mL of ammonia water, 15 mL of anhydrous ethanol, and 4 mL of deionized water were added thereto while stirring, and the mixture was stirred for 15 minutes to obtain a mixed solution;

[0056] Step (2): The mixed solution was transferred to a round-bottom flask, and the round-bottom flask was placed in an oil bath pot to immerse the liquid surface of the mixed solution, heated to 100 ° C. and reacted in the oil bath for 10 minutes, and then naturally cooled to room temperature in the air. After centrifugation, it was washed with deionized water three times and dried in a vacuum oven for 12 hours to obtain a powder material of carbon nanocage-loaded indium hydroxide;

[0057] Step (3): The dried carbon nanocage-loaded indium hydroxide powder material is subjected to high-temperature annealing at a temperature of 400° C. in an argon atmosphere for 1 h to obtain catalyst c.

[0058] Example 4

[0059] This embodiment provides a preparation method of catalyst d (loading amount is 20%, carbon nanocage-supported indium oxide catalyst annealed at 300°C in argon atmosphere for 3 hours and then annealed at 200°C in hydrogen atmosphere for 1 hour), the specific steps are as follows:

[0060] Step (1): 20 mg of carbon nanocages and 100 mg of indium nitrate were dissolved in 12 mL of deionized water, and the mixture was stirred thoroughly with a magnetic stirrer at a stirring rate of 300 rpm. 5 mL of ammonia water, 15 mL of anhydrous ethanol, and 4 mL of deionized water were added thereto while stirring, and the mixture was stirred for 15 minutes to obtain a mixed solution;

[0061] Step (2): The mixed solution was transferred to a round-bottom flask, the round-bottom flask was placed in an oil bath, the liquid surface of the mixed solution was immersed, and the mixture was heated to 80° C. in the oil bath for reaction for 30 min, and then naturally cooled to room temperature in air. After centrifugation, the mixture was washed three times with deionized water, and dried in a vacuum oven for 12 h to obtain a powder material of carbon nanocage-loaded indium hydroxide;

[0062] Step (3): The dried carbon nanocage-loaded indium hydroxide powder material was subjected to high-temperature annealing at 300° C. in an argon atmosphere for 3 h, and then annealed at 200° C. in a hydrogen atmosphere for 1 h, thereby obtaining catalyst d.

[0063] The X-ray crystal diffraction pattern of the catalyst d sample powder is as follows: Figure 4 As shown by Figure 4 It can be seen that the characteristic diffraction peaks of the sample completely correspond to the standard characteristic diffraction peaks of indium oxide PDF#06-0416 card, indicating that the sample did not undergo phase change or decomposition during the high-temperature annealing process and still maintained the crystalline phase of indium oxide. Figure 5 As shown by Figure 5 It can be seen that after annealing at 300℃ in argon atmosphere for 3h and then annealing at 200℃ in hydrogen atmosphere for 1h, the sample can be clearly observed to have a lighter contrast of carbon nanocages and a darker contrast of indium oxide, which is dispersed on the outer surface of carbon nanocages and in the gaps between adjacent cages, with an average size of about 16nm. The UV-visible diffuse reflectance spectrum of catalyst sample d is shown in the figure below. Figure 6 As shown by Figure 6 It can be seen that the reflectivity of the sample is 6-12% in the spectrum of wavelength 200-2300 nm, indicating that the sample has good light response in the entire spectrum.

[0064] Example 5

[0065] This specific embodiment provides a preparation method of catalyst e (loading amount is 20%, carbon nanocage-supported indium oxide catalyst is annealed at 200°C in argon atmosphere for 3h and then annealed at 300°C in hydrogen atmosphere for 2h), the specific steps are as follows:

[0066] Step (1): 20 mg of carbon nanocages and 100 mg of indium chloride were dissolved in 12 mL of deionized water, and the mixture was stirred thoroughly with a magnetic stirrer at a stirring rate of 300 rpm. 5 mL of ammonia water, 15 mL of anhydrous ethanol, and 4 mL of deionized water were added thereto while stirring, and the mixture was stirred for 15 minutes to obtain a mixed solution;

[0067] Step (2): The mixed solution was transferred to a round-bottom flask, the round-bottom flask was placed in an oil bath, the liquid surface of the mixed solution was immersed, and the mixture was heated to 80° C. in the oil bath for reaction for 30 min, and then naturally cooled to room temperature in air. After centrifugation, the mixture was washed three times with deionized water, and dried in a vacuum oven for 12 h to obtain a powder material of carbon nanocage-loaded indium hydroxide;

[0068] Step (3): The dried carbon nanocage-loaded indium hydroxide powder material is subjected to high-temperature annealing at a temperature of 200° C. in an argon atmosphere for 3 h, and then annealed at 300° C. in a hydrogen atmosphere for 2 h, thereby obtaining catalyst e.

[0069] The X-ray crystal diffraction pattern of the catalyst e sample powder is as follows: Figure 7 As shown. Figure 7 It can be seen that the characteristic diffraction peaks of the sample completely correspond to the standard characteristic diffraction peaks of indium oxide PDF#06-0416 card, indicating that the sample did not undergo phase change or decomposition during the high-temperature annealing process and still maintained the crystalline phase of indium oxide. Figure 8 As shown. Figure 8 It can be seen that after annealing at 200℃ in argon atmosphere for 3h and then annealing at 300℃ in hydrogen atmosphere for 2h, the sample can be clearly observed to have a lighter contrast of carbon nanocages and a darker contrast of indium oxide, which is dispersed on the outer surface of carbon nanocages and in the gaps between adjacent cages, with an average size of about 26nm. The UV-visible diffuse reflectance spectrum of catalyst e sample is shown in the figure below. Figure 9 As shown. Figure 9 It can be seen that the reflectivity of the sample is 6-12% in the spectrum of wavelength 200-2300 nm, indicating that the sample has good light response in the entire spectrum.

[0070] Test Example 1

[0071] Methanol catalytic performance test of various catalysts under thermal catalysis

[0072] Catalysts a, b, and c were ultrasonically dispersed in ethanol and evenly drop-coated on glass fiber filter paper. The catalysts were then transferred to a stainless steel stationary phase reactor. The catalytic performance of carbon dioxide hydrogenation to methanol under thermal catalysis was tested at a reaction temperature of 280°C, an ambient pressure of 2.0 MPa, and a gas flow rate ratio of N2:CO2:H2=2:2:6. The methanol catalytic performance of each catalyst is shown in Table 1.

[0073] Table 1 Methanol catalytic performance test of various catalysts under thermal catalysis

[0074]

[0075] Table 1 shows that catalyst a achieved a methanol formation rate of 218.9 μmol / gh with a methanol selectivity of 48.7%. Catalyst b achieved a methanol formation rate of 210.0 μmol / gh with a methanol selectivity of 38.5%. Catalyst c achieved a methanol formation rate of 373.4 μmol / gh with a methanol selectivity of 34.7%. Overall, catalyst a achieved the best catalytic performance.

[0076] Test Example 2

[0077] Methanol catalytic performance test of various catalysts under light-assisted thermal catalysis

[0078] Catalysts a, d, and e were ultrasonically dispersed in ethanol and evenly coated on glass fiber filter paper. They were then transferred to a stainless steel mobile phase reactor and illuminated with a full-spectrum xenon lamp with a wavelength of 300-2500 nm and an illumination intensity of 0.4 W·cm -2 The catalytic performance of photo-assisted thermal catalytic carbon dioxide hydrogenation to methanol was tested under the conditions of reaction temperature of 280°C, ambient pressure of 2.8 MPa, and gas flow rate ratio of N2:CO2:H2=2:2:6. The methanol catalytic performance of each catalyst is shown in Table 2.

[0079] Table 2 Methanol catalytic performance test of each catalyst under light-assisted thermal catalysis

[0080]

[0081] Table 2 shows that catalyst a achieved a methanol formation rate of 1809.4 μmol / gh with a methanol selectivity of 17.8%; catalyst d achieved a methanol formation rate of 1780.2 μmol / gh with a methanol selectivity of 17.4%; and catalyst e achieved a methanol formation rate of 1353.1 μmol / gh with a methanol selectivity of 18.2%. Overall, catalyst a demonstrated the best catalytic performance.

[0082] Test Example 3

[0083] Methanol catalytic performance test of various catalysts under photocatalysis

[0084] Catalyst a was ultrasonically dispersed in ethanol and evenly coated on glass fiber filter paper. It was then transferred to a stainless steel mobile phase reactor and illuminated with a full spectrum xenon lamp with a wavelength of 300-2500 nm and an illumination intensity of 2.75 W·cm -2 The catalytic performance of photocatalytic carbon dioxide hydrogenation to methanol was tested under the conditions of ambient pressure of 2.8 MPa and gas flow rate ratio of N2:CO2:H2=2:2:6. The methanol catalytic performance is shown in Table 3.

[0085] Table 3 Photocatalytic performance test of methanol catalysts

[0086]

[0087] Table 3 shows that the methanol production rate under photocatalysis is 1220.6 μmol / gh and the methanol selectivity is 96%. Under pure photocatalytic conditions, both the methanol production rate and methanol selectivity reach a high level.

[0088] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a carbon nanocage-supported indium oxide catalyst, characterized in that: The following steps are involved: S1: dissolving carbon nanocages and indium salt compounds in a solvent and mixing them uniformly to obtain a mixed solution; the mass ratio of the carbon nanocages to the indium salt compounds is 1:(5-10); S2: adding an alkaline compound to the mixed solution and performing a heating reaction to obtain carbon nanocage-loaded indium hydroxide powder; the heating reaction temperature is 60-100° C.; S3: calcining the carbon nanocage-supported indium hydroxide powder in an inert atmosphere to obtain the carbon nanocage-supported indium oxide catalyst; the calcination temperature in the inert atmosphere is 200-400° C., and the calcination time in the inert atmosphere is 1-3 hours.

2. The preparation method according to claim 1, characterized in that The step S3 further includes a step of calcining in a hydrogen atmosphere.

3. The preparation method according to claim 2, characterized in that The calcination temperature in the hydrogen atmosphere is 200-400° C., and the calcination time in the hydrogen atmosphere does not exceed 2 h.

4. The carbon nanocage-supported indium oxide catalyst prepared by the preparation method according to any one of claims 1 to 3.

5. The carbon nanocage-supported indium oxide catalyst according to claim 4, characterized in that The indium oxide is loaded on the surface of the carbon nanocage or between adjacent carbon nanocages.

6. The carbon nanocage-supported indium oxide catalyst according to claim 4, characterized in that The loading amount of the indium oxide is 20-40%.

7. Use of the carbon nanocage-supported indium oxide catalyst according to any one of claims 4 to 6 in the photothermal-photochemical synergistic catalytic hydrogenation of carbon dioxide to produce methanol.

8. The use according to claim 7, characterized in that The reaction conditions for preparing methanol by adding carbon dioxide to hydrogen include light irradiation, and the wavelength of the light is 300-2500 nm.

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