Photothermal catalyst for driving CO2 methanation in gas-solid system, preparation method and application thereof

Abstract

A photo-thermal catalyst for driving CO2 methanation in a gas-solid system, a preparation method and application thereof, the catalyst comprising a non-metal modified transition metal oxide semiconductor M x O y , a surface of the non-metal modified M x O y is modified with a sensitized photo-thermal layer, and the sensitized photo-thermal layer is loaded with a noble metal on the surface; the M x O y is selected from at least one of TiO2, Fe2O3 and ZrO2. The photo-thermal catalyst can better catalyze CO2 methanation under photo-thermal conditions.

Description

Technical Field

[0001] This invention relates to the field of photothermal catalytic reaction technology, specifically to a photothermal catalyst for driving the methanation of CO2 in a gas-solid system, its preparation method, and its application. Background Technology

[0002] The massive burning of fossil fuels has led to a sharp increase in atmospheric carbon dioxide concentration, causing a simultaneous rise in global average surface temperature and sea level. Converting carbon dioxide into chemical fuels through chemical catalysis is considered one of the most promising methods for mitigating the greenhouse effect and alleviating energy shortages. However, currently used thermocatalytic methods require harsh reaction conditions, are highly dependent on fossil fuels, and result in secondary CO2 emissions. In contrast, photocatalysis, which utilizes abundant solar energy to reduce CO2, offers milder reaction conditions and produces no secondary CO2 emissions, making it a current research hotspot in the field of CO2 conversion.

[0003] However, the efficiency of all current photocatalytic reactions is still far below the requirements of industrial production. This is mainly because the wide bandgap of commonly used catalysts in traditional photocatalysis limits the utilization of the solar spectrum, and most of the energy in the visible, near-infrared, and infrared regions cannot be utilized. In recent years, composite photocatalysts, such as heterojunctions, Z-Scheme systems, and sensitized systems, have been shown to effectively extend the photoresponse of catalysts to the near-infrared and infrared regions. In particular, photothermal catalysts based on noble metal nanoparticles and exhibiting the surface plasmon resonance effect (SPR) show superior conversion efficiency and product selectivity compared to single photocatalytic systems, improving the overall utilization efficiency of the solar spectrum. However, due to the following reasons, the practical application of photocatalytic CO2 methanation still faces significant challenges.

[0004] First, traditional photocatalysts primarily utilize a photo-excited single-electron transfer mechanism to achieve CO2 conversion reactions. The lifetime of the electron-hole pairs generated by photoexcitation determines the efficiency of the free radicals. This characteristic fundamentally renders increasing the reaction temperature through photothermal effects to improve quantum efficiency infeasible. The positive thermal effects of increased temperature, such as accelerated mass transfer and the provision of activation energy, are offset by the drastic shortening of the electron-hole pair lifetime with increasing temperature, and may even have a negative effect on temperature rise. Second, the efficiency of typical photocatalytic reactions is not linearly dependent on the intensity of incident light. Efficiency is higher at low incident light intensities, but decreases significantly at high intensities due to inherent self-quenching effects. This necessitates the use of large-area two-dimensional reactors under mild light irradiation conditions and at room temperature to ensure optimal quantum efficiency. This is clearly incompatible with large-scale industrial applications requiring limited reactor volume and high frequency.

[0005] Therefore, to achieve practical application of photocatalytic CO2 methanation, it is necessary to prepare photocatalysts that can be used in industrial applications. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a photothermal catalyst for driving CO2 methanation in a gas-solid system, its preparation method, and its application. This photothermal catalyst can effectively catalyze CO2 methanation under photothermal conditions.

[0007] As previously stated, this invention provides a photothermal catalyst for driving the methanation of CO2 in a gas-solid system, the catalyst comprising a non-metal-modified transition metal oxide semiconductor M x O y The non-metallic modified M x O y The surface is coated with a sensitized photothermal layer, and the surface of the sensitized photothermal layer is loaded with noble metal;

[0008] The M x O y It is selected from at least one of TiO2, Fe2O3, and ZrO2.

[0009] According to an embodiment of the present invention, the sensitized photothermal layer is a perylene diimide material (hereinafter referred to as PDI material) coated on M. x O y Surface formation.

[0010] According to an embodiment of the present invention, the loading amount of the PDI is 1-20 wt%, preferably 2-15 wt%, and more preferably 5-10 wt%.

[0011] According to an embodiment of the present invention, the PDI material has a structure as shown in Formula A;

[0012]

[0013] In formula A, X is independently selected from H and C. n1 H 2n1+1 Ph or (CH2) n2 COOH, where n1 is any integer from 1 to 5, and n2 is any integer from 0 to 5.

[0014] According to an embodiment of the present invention, a non-metal-modified transition metal oxide semiconductor M x O y M selected from N-doped transition metal oxide semiconductors x O y .

[0015] According to an embodiment of the present invention, the N-doped material is selected from 2-aminoterephthalic acid of formula B.

[0016]

[0017] In formula B, R1, R2, and R3 are each independently selected from H, CH3, CH2CH3, CH3O, or halogen X, preferably halogen X is Cl, Br, or F.

[0018] According to an embodiment of the present invention, the precious metal is selected from one or more of Pt, Ru, Pd, Au, and Ag.

[0019] According to an embodiment of the present invention, the loading of the precious metal is 0.1-5 wt%, preferably 0.2-3 wt%, and more preferably 0.5-2 wt%.

[0020] According to an embodiment of the present invention, the photothermal catalyst is a blocky morphology with a regular shape.

[0021] According to an embodiment of the present invention, the photothermal catalyst can be heated to a temperature greater than 155°C, for example, 168°C, under illumination.

[0022] According to an embodiment of the present invention, the photothermal catalyst, under illumination, can catalyze the hydrogenation of CO2 to produce methane, with a methane production rate greater than 3 mmol / g / h, preferably greater than 4 mmol / g / h, and more preferably greater than 4.5 mmol / g / h, for example 4.6 mmol / g / h, 4.2 mmol / g / h, 3.5 mmol / g / h, 4.1 mmol / g / h, 5.5 mmol / g / h, 4.3 mmol / g / h, or 4.5 mmol / g / h.

[0023] According to an embodiment of the present invention, the photothermal catalyst exhibits a selectivity greater than 95% for catalytic hydrogenation of CO2 to methane, preferably greater than 97%, for example, 99.65%.

[0024] Secondly, the present invention provides a method for preparing the above-mentioned photothermal catalyst, comprising the following steps:

[0025] (1) N-homogeneously doped NMnO4 was prepared by reacting a non-metallic doped material as a linker with a MOF precursor with transition metal ions as nodes. x O y ;

[0026] (2) NM x O y NM was prepared by self-assembly of PDI material.x O y / PDI;

[0027] (3) In NM x O y / PDI surface deposition of noble metals to obtain Noble / NM x O y / PDI / Precious Metals.

[0028] According to an embodiment of the present invention, step (1) includes the following steps: dissolving the N-doped material in a solvent, adding an organometallic ester or salt, performing a hydrothermal reaction to obtain an amino-modified MOF, and calcining the amino-modified MOF to obtain NM x O y .

[0029] According to an embodiment of the present invention, the solvent is selected from good solvents for N-doped materials, such as a mixed solution of N,N-dimethylformamide and methanol, wherein the volume ratio of N,N-dimethylformamide to methanol is 1:(0.2-1).

[0030] According to an embodiment of the present invention, the organometallic ester or salt is selected from at least one of isopropyl titanate, ferric nitrate nonahydrate, and zirconium tetrachloride, for example, isopropyl titanate.

[0031] According to an embodiment of the present invention, dissolving the N-doped material in a solvent, adding an organometallic ester or salt, and hydrothermally reacting to obtain an amino-modified MOF includes the following steps: dissolving the N-doped material in a mixed solution of N,N-dimethylformamide and methanol, adding an organometallic ester or salt, stirring, and then hydrothermally reacting at a constant temperature to obtain an MOF precursor with amino groups attached to its surface, and washing and drying to obtain an amino-modified MOF material.

[0032] According to an embodiment of the present invention, the hydrothermal reaction includes reacting at 100–160°C for 12–24 h, preferably at 120–150°C for 15–20 h.

[0033] According to an embodiment of the present invention, the washing and drying includes the following steps: washing the hydrothermal reaction product with DMF and methanol several times in sequence, and then drying it at a temperature of 60-120°C for 2-48 hours.

[0034] According to an embodiment of the present invention, the MOF material is at least one of Ti-MOF, Fe-MOF or Zr-MOF.

[0035] According to an embodiment of the present invention, the calcination of the amino-modified MOF is carried out in a muffle furnace, preferably for a calcination time of 2 to 6 hours and a calcination heating rate of 1 to 8 °C / min.

[0036] According to an embodiment of the present invention, N-homogeneously doped NM x O y It includes at least one of N-TiO2, N-Fe2O3 or N-ZrO2, wherein N-TiO2, N-Fe2O3 or N-ZrO2 are N-doped transition metal semiconductor materials.

[0037] According to an embodiment of the present invention, step (2) includes the following steps: taking NM x O y PDI material was added and dispersed in an acidic solution, and water was added to the dispersion under an ice-water bath with stirring to obtain NM. x O y / PDI.

[0038] According to an embodiment of the present invention, the acidic solution is selected from at least one of sulfuric acid, nitric acid, and hydrochloric acid, for example, concentrated sulfuric acid.

[0039] According to an embodiment of the present invention, the mass fraction of PDI material in the dispersion is 0.5 to 30 wt%, preferably 1 to 20 wt%.

[0040] As an example, step (2) includes the following steps: NM x O y The material was soaked and stirred in 98% sulfuric acid for 8–15 hours, then PDI was added and the mixture was fully dispersed. Deionized water was then added and stirred under an ice-water bath. After filtration, washing, and drying, NM was obtained. x O y / PDI.

[0041] According to an embodiment of the present invention, step (3) includes the following steps: taking NM x O y PDI was dispersed in an acidic aqueous solution of a noble metal salt, reacted and degassed in the dark, and then irradiated with light for at least 30 minutes to obtain Noble / NM x O y / PDI.

[0042] According to an embodiment of the present invention, the noble metal salt in step (3) is selected from one or more of potassium chloroplatinate, potassium chloropalladium, chloroauric acid, silver nitrate and ruthenium chloride or their respective hydrates.

[0043] According to an embodiment of the present invention, in step (3), the concentration of the noble metal salt in the acidic aqueous solution is 0.01 to 5 mmol / L, preferably the concentration of the noble metal salt in the acidic aqueous solution is 0.05 to 2 mmol / L.

[0044] According to an embodiment of the present invention, step (3) of reacting and degassing in the dark includes the following steps: reacting NM... x O y / PDI is dispersed in an acidic aqueous solution of a noble metal salt and stirred in the dark for 0.5 to 2 hours, followed by bubbling inert gas for 0.2 to 1 hour.

[0045] According to an embodiment of the present invention, the light intensity used for illumination in step (3) is 0.1 to 1 W / cm². 2 The illumination time is 0.5 to 4 hours.

[0046] According to an embodiment of the present invention, step (3) further includes washing the obtained product at least three times with a reaction solvent after the reaction, and drying the product at a temperature of 60 to 120°C for 2 to 48 hours after washing.

[0047] Thirdly, the present invention also provides a method for the hydrogenation and methanation of CO2 in a gas-solid static / flow system using the above-mentioned photothermal catalyst.

[0048] According to an embodiment of the present invention, the method for CO2 hydrogenation methanation includes the following steps:

[0049] The photothermal catalyst described above is placed in a photoreactor, CO2 is introduced into the reactor, and the photothermal catalyst is irradiated with simulated sunlight.

[0050] According to an embodiment of the present invention, the photocatalytic reactor is a light-transmitting reactor and Pyrex glass is selected.

[0051] According to an embodiment of the present invention, the mass of the photocatalyst can be 1 to 1000 mg.

[0052] According to an embodiment of the present invention, the photothermal catalyst is first coated on the surface of a support, and then the support is placed inside the photoreactor, the support being, for example, a quartz sheet.

[0053] According to an embodiment of the present invention, the flow rate of CO2 introduced into the reactor is 0 to 50 mL / min.

[0054] According to an embodiment of the present invention, the light intensity of the irradiation light is 0.1–5 W / cm². 2 The irradiation time is 0.5 hours or more.

[0055] Beneficial effects

[0056] 1) This invention uses perylene diimide (PDI) as a sensitizer and self-assembles doped metal oxide semiconductor nanomaterials to prepare NM x O y / PDI photothermal sensitized catalyst material, then deposited noble metal, ultimately forming Noble / NM x O y / PDI photothermal sensitization catalyst is used to facilitate the smooth gas-solid phase photothermal catalysis reaction H2O(g) + CO2 → CH4 + O2.

[0057] Perylene diimide (PDI) materials are commonly used organic building blocks with large π-conjugated frameworks and many family members. Due to their excellent visible light absorption and excitation properties, good photothermal stability, and high photothermal conversion efficiency, they are used in photocatalytic degradation of organic pollutants and photothermal catalysis. However, pure PDI materials, after excitation, typically lack sites for CO2 reduction reactions and generally cannot be used alone for CO2 conversion. This invention addresses this by combining PDI materials with NM... x O y Effective self-assembly enables PDI materials to integrate with transition metal oxide semiconductors such as TiO2, Fe2O3, and ZrO2. x O y The photocatalyst is effectively composited and its energy levels are matched. Doping with main group nonmetal N lowers the binding energy of MO, allowing the M site to possess classic Lewis acid sites. When incident light irradiates PDI, it can smoothly oxidize and decompose H2O into O2 and H+. + After that, it is passed to M x O y Electrons in the conduction band can bind to H + The metal-negative hydrogen species MH is generated at the Lewis acid site. Unlike ordinary free radical species, MH has a longer lifetime and stability, and its reactivity is also very high. It can effectively undergo nucleophilic attack on CO2. Since the nucleophilic attack reaction is the rate-determining step, the significant photothermal effect—that is, the heat energy converted from the de-excitation light energy—will greatly enhance the nucleophilic reaction rate of the negative hydrogen species MH. This changes the efficiency of photocatalytic reaction from another perspective. For the first time, the catalyst of this invention improves the solar energy utilization efficiency of photocatalysis in a thermally assisted manner to a practically usable level, showing great application potential.

[0058] (2) This invention changes the free radical pathway of single electron transfer induced by temperature-independent electron-hole pairs to a temperature-dependent pathway mainly based on photogenerated Lewis acid nucleophilic catalysis; at the same time, it expands the application range of solar energy spectrum as much as possible; in addition, this invention does not use an external heating source but only uses focused high-intensity solar energy to make the catalyst surface temperature reach 300°C to nucleophilically attack CO2.

[0059] (3) This invention studies the process of obtaining valuable hydrocarbons CH4 from CO2 through photothermal hydrogenation, which can effectively alleviate the greenhouse effect caused by fossil fuel combustion and at the same time alleviate the energy shortage crisis to a certain extent.

[0060] (4) The photothermal catalyst of the present invention can provide the energy required for the reaction by locally heating the catalyst site with light energy in the gas-solid reaction device, realize the hydrogenation conversion of CO2 with a high conversion frequency under mild conditions, and exhibit excellent catalytic stability in the flow system.

[0061] (5) The photothermal catalyst prepared by the present invention is simple and efficient in the preparation method of the photothermal catalyst for driving CO2 hydrogenation in a gas-solid flow device. It can be mass-produced, has extremely low recycling cost, excellent recycling performance, is conducive to large-scale production, and has great potential for industrial CO2 hydrogenation. Attached Figure Description

[0062] Figure 1 These are photographs of the dispersion sheets corresponding to different photothermal catalysts in the test examples;

[0063] Figure 2 These are surface thermal images of different photothermal catalysts under simulated sunlight conditions in the test examples;

[0064] Figure 3 This is a diagram of the gas-solid photothermal driven CO2 hydrogenation reaction apparatus in the test example;

[0065] Figure 4 The graph shows the reaction rates of CO2 hydrogenation methanation catalyzed by different photocatalysts in the test examples. Detailed Implementation

[0066] The photothermal catalyst of the present invention, its preparation method, and its application will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0067] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0068] Example 1

[0069] A method for preparing a photothermal catalyst driving the methanation of CO2 in a gas-solid system includes the following steps:

[0070] S1. Dissolve 2.17 g of 2-aminoterephthalic acid in a mixture of 40 mL of DMF and methanol (DMF:CH3OH = 5:1). Sonicate the solution for 0.5 h, then add 0.8526 g of isopropyl titanate and sonicate for 5 min. Transfer the resulting mixture to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and react in a constant temperature drying oven at 150 °C for 24 h. Wash the resulting solid product three times each with DMF and methanol, and then vacuum dry at 80 °C for 12 h to obtain NH2-MIL-125.

[0071] S2. The prepared NH2-MIL-125 was heated to 450℃ at a heating rate of 1℃ / min and kept in air for 3h to obtain a light yellow powder. The light yellow powder was washed three times with deionized water and then vacuum dried for 12h to obtain N-TiO2.

[0072] S3. 0.3 g of N-TiO2 powder was added to 10 mL of concentrated sulfuric acid and stirred for 12 h. Then, 1 wt% of perylene diimide powder was added and ultrasonically dispersed for 2 h. Subsequently, 100 mL of deionized water was rapidly added in an ice-water bath, and stirring was continued for 6 h. Finally, the product was filtered, washed with a large amount of deionized water until neutral, and dried at 60 °C for 12 h to obtain the N-TiO2 / PDIH composite material.

[0073] S4. Disperse 3 mg potassium chloroplatinate and 100 mg N-TiO2 / PDIH in 50 mL of deionized water, stir in the dark for 1 h, and then introduce argon gas into the reaction system by bubbling for 0.5 h at 0.5 w / cm². 2 After irradiation under full light for 3 hours, the resulting black powder was washed three times with deionized water to obtain the photothermal catalyst Pt / N-TiO2 / PDIH.

[0074] Example 2

[0075] S1. Dissolve 1.36 g of 2-aminoterephthalic acid in a mixture of 40 mL of DMF and methanol (DMF:CH3OH = 5:1). Sonicate the solution for 0.5 h, then add 1.25 g of zirconium tetrachloride and sonicate for 5 min. Transfer the resulting mixed solution to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and react in a constant temperature drying oven at 120 °C for 12 h. Wash the obtained solid product three times each with DMF and methanol, and then dry it under vacuum at 80 °C for 12 h to obtain NH2-UIO-66.

[0076] S2. The prepared NH2-UIO-66 was heated to 450℃ at a heating rate of 1℃ / min and kept in air for 3h to obtain a light yellow powder. The light yellow powder was washed three times with deionized water and then vacuum dried for 12h to obtain N-ZrO2.

[0077] S3. 0.3 g of N-ZrO2 powder was added to 10 mL of concentrated sulfuric acid and stirred for 12 h. Then, 1 wt% of perylene diimide powder was added and ultrasonically dispersed for 2 h. Subsequently, 100 mL of deionized water was rapidly added in an ice-water bath, and stirring was continued for 6 h. Finally, the product was filtered, washed with a large amount of deionized water until neutral, and dried at 60 °C for 12 h to obtain the N-ZrO2 / PDIH composite material.

[0078] S4. Disperse 3 mg potassium chloroplatinate and 100 mg N-ZrO2 / PDIH in 50 mL of deionized water, stir in the dark for 1 h, and then introduce argon gas into the reaction system by bubbling for 0.5 h at 0.5 w / cm². 2 After irradiation under full light for 3 hours, the resulting black powder was washed three times with deionized water to obtain the photothermal catalyst Pt / N-ZrO2 / PDIH.

[0079] Example 3

[0080] S1. Dissolve 1.79 g of 2-aminoterephthalic acid in a mixture of 40 mL of DMF and methanol (DMF:CH3OH = 5:1). Stir the solution ultrasonically for 0.5 h. Then add 1.54 g of ferric nitrate nonahydrate and sonicate for 5 min. Transfer the resulting mixed solution to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and react in a constant temperature drying oven at 140 °C for 12 h. Wash the obtained solid product three times each with DMF and methanol, and then dry it under vacuum at 80 °C for 12 h to obtain NH2-MIL-101.

[0081] S2. The prepared NH2-MIL-101 was heated to 450℃ at a heating rate of 1℃ / min and kept in air for 3h to obtain a light yellow powder. The light yellow powder was washed three times with deionized water and then vacuum dried for 12h to obtain N-Fe2O3.

[0082] S3. 0.3 g of N-Fe2O3 powder was added to 10 mL of concentrated sulfuric acid and stirred for 12 h. Then, 1 wt% of perylene diimide powder was added and ultrasonically dispersed for 2 h. Subsequently, 100 mL of deionized water was rapidly added in an ice-water bath, and stirring was continued for 6 h. Finally, the product was filtered, washed with a large amount of deionized water until neutral, and dried at 60 °C for 12 h to obtain the N-Fe2O3 / PDIH composite material.

[0083] S4. Disperse 3 mg potassium chloroplatinate and 100 mg N-Fe₂O₃ / PDIH in 50 mL of deionized water, stir in the dark for 1 h, and then introduce argon gas into the reaction system by bubbling for 0.5 h at 0.5 w / cm². 2 After irradiation under full light for 3 hours, the resulting black powder was washed three times with deionized water to obtain the photothermal catalyst Pt / N-Fe2O3 / PDIH.

[0084] Example 4

[0085] Unlike Example 1, in S4, 0.1 mmol / L chloroauric acid and 100 mg N-TiO2 / PDIH were dispersed in deionized water and reacted under light to prepare Au / N-TiO2 / PDIH.

[0086] Example 5

[0087] Unlike Example 1, in S4, 0.1 mmol / L potassium chloropalladium and 100 mg N-TiO2 / PDIH were dispersed in deionized water and reacted under light to prepare Pd / N-TiO2 / PDIH.

[0088] Example 6

[0089] Unlike Example 1, in S3, 0.3 g of N-TiO2 powder was added to 10 mL of concentrated sulfuric acid and stirred for 12 h. Then, 1 wt% of PDI-COOH powder was added to prepare Pt / N-TiO2 / PDI-COOH.

[0090] Example 7

[0091] Unlike Example 1, in S3, 0.3 g of N-TiO2 powder was added to 10 mL of concentrated sulfuric acid and stirred for 12 h. Then, 1 wt% of PDI-Ph powder was added to prepare Pt / N-TiO2 / PDI-Ph.

[0092] Example 8

[0093] The conditions remained the same as in Example 1, except that in S1, 2.79 g of 2-amino-3-methylterephthalic acid was dissolved in a mixture of 40 mL of DMF and methanol (DMF:CH3OH = 5:1).

[0094] Example 9

[0095] The conditions remained the same as in Example 1, except that in S1, 3.19 g of 2-amino-3-bromoterephthalic acid was dissolved in a mixture of 40 mL of DMF and methanol (DMF:CH3OH = 5:1).

[0096] Comparative Example 1

[0097] S1. Dissolve 2.1738 g of 2-aminoterephthalic acid in a mixture of 40 mL of DMF and methanol (DMF:CH3OH = 5:1). The solution is ultrasonically stirred for 0.5 h. Then, 0.8526 g of isopropyl titanate is added and ultrasonically stirred for 5 min. The resulting mixed solution is transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and reacted in a constant temperature drying oven at 150 °C for 24 h. The resulting solid product is washed three times each with DMF and methanol, and then vacuum dried at 80 °C for 12 h to obtain NH2-MIL-125.

[0098] S2. The prepared NH2-MIL-125 was heated to 450℃ at a heating rate of 1℃ / min and kept in air for 3h to obtain a light yellow powder. The light yellow powder was washed three times with deionized water and then vacuum dried for 12h to obtain N-TiO2.

[0099] Comparative Example 2

[0100] S1. Dissolve 2.1738 g of 2-aminoterephthalic acid in a mixture of 40 mL of DMF and methanol (DMF:CH3OH = 5:1). The solution is ultrasonically stirred for 0.5 h. Then, 0.8526 g of isopropyl titanate is added and ultrasonically stirred for 5 min. The resulting mixed solution is transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and reacted in a constant temperature drying oven at 150 °C for 24 h. The resulting solid product is washed three times each with DMF and methanol, and then vacuum dried at 80 °C for 12 h to obtain NH2-MIL-125.

[0101] S2. The prepared NH2-MIL-125 was heated to 450℃ at a heating rate of 1℃ / min and kept in air for 3h. The resulting light yellow powder was washed three times with deionized water and then vacuum dried for 12h to obtain N-TiO2.

[0102] S3. 0.3 g of N-TiO2 powder was added to 10 mL of concentrated sulfuric acid and stirred for 12 h. Then, 1 wt% of perylene imide powder was added and ultrasonically dispersed for 2 h. Subsequently, 100 mL of deionized water was rapidly added in an ice-water bath, and stirring was continued for 6 h. Finally, the product was filtered, washed with a large amount of deionized water until neutral, and dried at 60 °C for 12 h to obtain the N-TiO2 / PDIH composite material.

[0103] Performance testing

[0104] Photothermal catalytic performance test of CO2 hydrogenation driven in a gas-solid flow system: 5 mg of the photothermal catalysts prepared in Example 1 and Comparative Examples 1 and 2, and PDIH were added to 5 mL of deionized water, ultrasonically dispersed, and drop-coated onto a quartz plate with a radius of 1 cm. The plates were then dried at 70 °C to obtain uniformly dispersed sample discs. (See [reference]). Figure 1 As shown, Figure 1 (a) is a dispersion of the N-TiO2 sample prepared in Comparative Example 1, which is light yellow in color. Figure 1 (b) is a dispersion of the PDIH sample, which is blackish-gray in color. Figure 1 (c) is a dispersion of the N-TiO2 / PDIH sample prepared in Comparative Example 2, which is purplish-red. Figure 1 (d) is a black dispersion sheet of the Pt / N-TiO2 / PDIH photothermal catalytic material prepared in Example 1.

[0105] See Figure 2 The figure shows the surface temperature thermal imaging of the four dispersions under simulated sunlight conditions. As can be seen from the figure, the catalyst temperature rises rapidly after illumination and reaches a stable state within 5 minutes. The temperature of the N-TiO2 sample prepared in Comparative Example 1 is 56℃ under illumination. When it is combined with perylene imide, the temperature of the sample c in Comparative Example 2 can reach 153℃, indicating that the perylene imide photothermal layer is effectively combined on the surface of N-TiO2. The surface temperature of the PDIH sample b is 155.1℃, indicating that PDIH itself has photothermal effect. The surface temperature of the catalyst in sample d prepared in Example 1 can reach 168℃, indicating that after loading Pt, due to the plasmon effect on its surface, it exhibits a higher surface temperature, further indicating that sample d has a better photothermal effect, which is beneficial to the photothermal-driven hydrogenation conversion reaction of CO2.

[0106] The above-mentioned dispersible tablets were added sequentially to the gas-solid reaction apparatus, see [reference]. Figure 3 As shown, the gas-solid reaction apparatus includes a reactor and a light source. The reactor provides the space for the gas-solid reaction, and the catalyst is placed inside the reactor. The light source is used to irradiate the reactor, especially the catalyst surface, and simulates sunlight. The reactor also has an inlet and an outlet. The inlet is used to introduce CO2, and the outlet is used to exhaust the reacted gases. The inlet is connected to a gas source via an inlet pipe, which is equipped with a bubbler to provide humidified CO2 to the reactor. The outlet is connected to a detection device, such as a gas chromatograph. In addition, the reaction apparatus also includes an infrared thermal imager to monitor the temperature of the catalyst during the reaction.

[0107] The aforementioned dispersion sheets were placed into a flowing gas-solid reaction apparatus. Through three cycles of vacuuming and CO2 purging, the entire apparatus was filled with moistened CO2. A 300W Xe lamp was used to irradiate the catalyst surface at a light intensity of 1W / cm². 2 Subsequently, moistened CO2 was continuously introduced into the reaction system through a flow meter at a flow rate of 10 sccm and a bubbler filled with deionized water. The other end was connected to a gas chromatograph to monitor the CH4 production online. At the same time, an infrared thermal imager was used to monitor the temperature of the catalyst during the reaction process. This data was used to evaluate the catalytic performance of the photothermal catalyst and the photothermal conversion efficiency of the photothermal catalyst.

[0108] See Figure 4 The figure shows the reaction efficiency of photo-driven CO2 hydrogenation of the photothermal catalytic materials prepared in Example 1 and Comparative Examples 1-2 of this invention. All catalysts only detected CH4, and no other carbon-containing products were detected. As can be seen from the figure, the photothermal catalytic material sample prepared in Example 1 showed the highest conversion efficiency, and its CH4 generation rate could reach 4.6 mmol / g / h. Considering the H2 generated by the system, its CH4 selectivity could reach 99.65%. The photothermal CH4 generation rates of Comparative Examples 1 and 2 were 0.07 mmol / g / h and 0.5 mmol / g / h, respectively, and the photothermal CH4 generation rate of PDIH was 0.3 mmol / g / h.

[0109] See Figure 4 As shown, in the photo-driven CO2 hydrogenation of the photothermal catalytic materials prepared in Examples 1-7 of this invention, the CH4 generation rates are 4.6 mmol / g / h, 4.2 mmol / g / h, 3.5 mmol / g / h, 4.1 mmol / g / h, 5.5 mmol / g / h, 4.3 mmol / g / h, and 4.5 mmol / g / h, respectively, all of which have high CH4 generation rates.

[0110] The specific embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above exemplary embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a photothermal catalyst for driving the methanation of CO2 in a gas-solid system, characterized in that, The steps include the following: (1) Dissolve the N-doped material in a solvent, add an organometallic ester or metal salt, and perform a hydrothermal reaction at 100~160℃ for 12~24h to obtain an amino-modified MOF. Calcine the amino-modified MOF to obtain N-M x O y ; The N-doped material is selected from 2-aminoterephthalic acid; The organometallic ester or metal salt is selected from at least one of isopropyl titanate, ferric nitrate nonahydrate and zirconium tetrachloride. (2) NM x O y PDI material was added and dispersed in an acidic solution, and water was added to the dispersion under an ice-water bath with stirring to obtain N-M. x O y / PDI; (3) NM x O y PDI was dispersed in an acidic aqueous solution of a noble metal salt, reacted and degassed in the dark, and then irradiated with light for at least 30 minutes to obtain Noble / NM x O y / PDI; The catalyst comprises N-modified transition metal oxide semiconductor M x O y The N-modified M x O y The surface is coated and modified with perylene imide (PDI) material, and the surface of the perylene imide (PDI) material is loaded with noble metals; The NM x O y It includes at least one of N-TiO2, N-Fe2O3 or N-ZrO2.

2. The preparation method according to claim 1, characterized in that, The loading of the PDI material is 1-20 wt%.

3. The preparation method according to claim 1, characterized in that, The PDI material has a structure as shown in Formula A; Formula A In formula A, X is independently selected from H and C. n1 H 2n1+1 Ph or (CH2) n2 COOH, where n1 is any integer from 1 to 5, and n2 is any integer from 0 to 5.

4. The preparation method according to any one of claims 1-3, characterized in that, The precious metal is selected from one or more of Pt, Ru, Pd, Au, and Ag.

5. The preparation method according to any one of claims 1-3, characterized in that, The loading of the precious metal is 0.1-5 wt%.

6. The preparation method according to claim 1, characterized in that, The solvent mentioned in step (1) is selected from good solvents for N-doped materials.

7. The preparation method according to claim 1, characterized in that, The process of dissolving N-doped material in a solvent, adding organometallic esters or metal salts, and then hydrothermally reacting to obtain amino-modified MOFs includes the following steps: dissolving N-doped material in a mixed solution of N,N-dimethylformamide and methanol, adding organometallic esters or metal salts, stirring, and then hydrothermally reacting at a constant temperature to obtain MOF precursors with amino groups attached to their surfaces, followed by washing and drying to obtain amino-modified MOF materials.

8. The preparation method according to any one of claims 1-3, characterized in that, The acidic aqueous solution is selected from at least one of sulfuric acid, nitric acid, and hydrochloric acid.

9. The preparation method according to any one of claims 1-3, characterized in that, The mass fraction of PDI material in the dispersion is 0.5~30wt%.

10. The preparation method according to any one of claims 1-3, characterized in that, In step (3), the precious metal salt is selected from one or more of potassium chloroplatinate, potassium chloropalladium, chloroauric acid, silver nitrate and ruthenium chloride or their respective hydrates, and the concentration of the precious metal salt in the acidic aqueous solution is 0.01~5 mmol / L.

11. The preparation method according to any one of claims 1-3, characterized in that, The light intensity used for illumination in step (3) is 0.1~1w / cm. 2 The illumination time is 0.5~4 hours.

12. A method for the hydrogenation and methanation of CO2 in a gas-solid static / flow system catalyzed by a photothermal catalyst prepared according to any one of claims 1-11, characterized in that, The process includes the following steps: placing the photothermal catalyst in a photoreactor, introducing CO2 into the reactor, and irradiating the photothermal catalyst with simulated sunlight.

13. The method as described in claim 12, characterized in that, The mass of the photothermal catalyst is 1~1000 mg; And / or, the flow rate of CO2 introduced into the reactor is 0~50 mL / min and is not 0; And / or, the intensity of the simulated sunlight is 0.1~5 W / cm². 2 The irradiation time is 0.5 hours or more.

Images