Hollow multilayer heterostructure catalyst for photo-thermal deoxidation of fatty acid and preparation method of hollow multilayer heterostructure catalyst

Abstract

The invention discloses a hollow multilayer heterostructure catalyst for photo-thermal deoxidation of fatty acid and a preparation method. The inner layer of the catalyst is alloy nanoparticles of one or more of Ru, Pd, Au, Pt, Rh, Cu, Ni, Co and Ag, and the outer layer of the catalyst is a heterojunction formed by a metal organic framework material and one or two of TiO2 and C3N4. Metal or alloy is coated in a metal organic framework material, and then one or two of TiO2 and C3N4 are loaded on the outer surface of the metal organic framework material in a self-assembly or impregnation loading mode. The prepared catalyst is high in catalytic efficiency, capable of achieving efficient photo-thermal deoxidation of fatty acid to prepare alkane components, high in stability and wide in application range.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of photo-thermal catalytic material and its preparation method, specifically relates to a kind of hollow multilayer heterostructure catalyst for fatty acid photo-thermal deoxidation and preparation method. BACKGROUND

[0002] With the continuous growth of global energy demand and the depletion of fossil fuel resources, developing renewable, green and efficient biomass energy conversion technology has become a research hotspot in the field of energy. Fatty acids, as a kind of biomass raw material widely existing in animal and vegetable fats, have the characteristics of long carbon chain structure, abundant source and low cost, and are considered as an ideal precursor for preparing renewable alkane fuels (such as biodiesel and aviation kerosene).

[0003] Traditional fatty acid deoxidation needs to be carried out under high temperature and high pressure hydrogen conditions, which has high energy consumption, strict equipment requirements, poor economy and safety, low product selectivity, and is easy to cause catalyst deactivation. Photocatalytic technology has broad prospects in fatty acid decarboxylation to prepare alkanes due to its advantages of mild reaction conditions, low energy consumption and environmental friendliness. For example, CN201811469331.4 and CN202211469112.2 respectively report a method for preparing alkanes by decarboxylation of fatty acids using titanium dioxide-based catalyst under ultraviolet or visible light irradiation, with an alkane yield of more than 90%. In addition, CN202310357265.6 and CN202510555673.1 respectively introduce a method for preparing alkanes and by-product hydrogen by decarboxylation coupling of fatty acids under inert atmosphere based on Pt@C3N4 and organic azine photocatalyst. However, this method still has problems such as high recombination rate of photo-generated carriers, weak response to long-wave light and low quantum efficiency, which limits its industrial application. In order to further improve the efficiency, economy and practicability of fatty acid preparation of alkanes, photo-thermal synergistic catalytic technology has gradually become a research hotspot.

[0004] CN202410253827.7 discloses a Pt / TiO2-C3N4 porous heterojunction composite material for catalyzing fatty acid hydrogenation deoxidation under photo-thermal synergistic conditions, which improves the photo-generated electron-hole separation efficiency and reaction rate. The existing photo-thermal synergistic catalytic system still has technical shortcomings. On the one hand, the photo-thermal conversion efficiency and catalytic activity of supported noble metal catalysts are difficult to be optimized simultaneously. On the other hand, the porous structure design of the catalyst is insufficient, which limits the adsorption and diffusion of long-chain fatty acid molecules on the surface of the catalyst, affecting the reaction rate and substrate conversion rate. SUMMARY

[0005] The present application provides a kind of hollow multilayer heterostructure catalyst and preparation method, which has high catalytic efficiency and stability, long service life, can be used for fatty acid photo-thermal deoxidation to prepare alkanes and aviation oil components.

[0006] Technical solution: A hollow multilayer heterostructure catalyst for photothermal deoxygenation of fatty acids, wherein the inner layer of the catalyst is one or more nano-metal particles or alloys selected from Ru, Pd, Au, Pt, Rh, Cu, Ni, Co, and Ag, and the outer layer is a heterojunction formed by a metal-organic framework material and one or two of TiO2 and C3N4.

[0007] A method for preparing a hollow multilayer heterostructure catalyst for photothermal deoxygenation of fatty acids includes the following steps: Step (1) Prepare nano-metal particles or alloys, and encapsulate the nano-metal particles or alloys in a metal-organic framework material by ultrasound-assisted method; Step (2) Using the corresponding precursor, one or both of TiO2 and C3N4 are loaded onto the outer surface of the metal-organic framework material by self-assembly or impregnation.

[0008] This invention discloses a hollow multilayer heterostructure catalyst for photothermal deoxygenation of fatty acids and its preparation method. The inner layer of the catalyst consists of one or more alloy nanoparticles selected from Ru, Pd, Au, Pt, Rh, Cu, Ni, Co, and Ag, while the outer layer is a heterostructure formed by a metal-organic framework (MOF) and one or two of TiO2 and C3N4. The catalyst is prepared by coating a metal or alloy into the MOF and then loading one or two of TiO2 and C3N4 onto the outer surface of the MOF through self-assembly or impregnation. The catalyst prepared by this invention exhibits high catalytic efficiency, enabling efficient photothermal deoxygenation of fatty acids to produce alkane components. It also demonstrates high catalyst stability and a wide range of applications.

[0009] Beneficial effects: Compared with the prior art, the significant advantages of this invention are: 1. The unique composition, structure, and defect characteristics of the heterojunction on the outer layer of the catalyst can improve the efficiency of fatty acid adsorption and dissociation to generate alkyl radicals, thereby improving the fatty acid conversion efficiency; 2. Confinement of nano-metal particles can effectively improve the stability of catalysts, extend catalyst lifetime, and further improve the dissociation and directional migration efficiency of hydrogen. 3. The multilayer controllable structure of the catalyst creates close-fitting hydrogen and fatty acid activation sites, constructing a hydrogen-rich microenvironment around alkyl radicals. This can enhance the adsorption and activation of reactants, promote the improvement of reaction efficiency, and also regulate and inhibit side reactions such as alkyl radical polymerization or oxidation. Detailed Implementation

[0010] The technical solution of the present invention will be described in detail below with reference to the implementation process: A hollow multilayer heterostructure catalyst for photothermal deoxygenation of fatty acids, wherein the inner layer of the catalyst is one or more nano-metal particles or alloys selected from Ru, Pd, Au, Pt, Rh, Cu, Ni, Co, and Ag, and the outer layer is a heterostructure formed by a metal-organic framework material and one or two of TiO2 and C3N4.

[0011] The loading of nano-metal particles or alloys in the catalyst is 0.1-10.0 wt% based on the total mass, and the mass ratio of one or two of TiO2 and C3N4 to the metal-organic framework material is 0.1-10, with a particle size of 1-20 nm.

[0012] The metal-organic framework material in the catalyst is one of UiO-66, MOF-808, or MIL-125, with one or more of Zr, Ti, or Ce as the central ion. The particle size of the metal-organic framework material is 100-200 nm.

[0013] A method for preparing a hollow multilayer heterostructure catalyst for photothermal deoxygenation of fatty acids includes the following steps: Step (1) Prepare nano-metal particles or alloys, and encapsulate the nano-metal particles or alloys in a metal-organic framework material by ultrasound-assisted method; Step (2) Using the corresponding precursor, one or both of TiO2 and C3N4 are loaded onto the outer surface of the metal-organic framework material by self-assembly or impregnation.

[0014] The C3N4 precursor is at least one of urea, melamine, and dicyandiamide. The TiO2 is prepared from the precursor through controlled hydrolysis and calcination, or is commercially available anatase titanium dioxide. The precursor is at least one of titanium tetrachloride, titanate, and MIL-125.

[0015] Example 1: A dispersion of Pt nanoparticles with a particle size of 2 nm was prepared. An appropriate amount of the dispersion was used to encapsulate the nanoparticles in 1.0 g of the prepared Zr-based UiO-66 using an ultrasonic-assisted solvent reflux method, yielding intermediate S1. S1 was dispersed in 100 mL of ethanol solution, and 10.0 g of anatase TiO2 with a particle size of 1 nm was added. After stirring and reflux for 3 h, the mixture was cooled, and the solid obtained by centrifugation was the target catalyst C1. Analysis showed that the catalyst had a Pt loading of 0.1% (based on total mass), an organic framework particle size of 200 nm, a TiO2 to Ce / Zr-based MOF-808 mass ratio of 10:1, and a particle size of 1 nm.

[0016] Example 2: A dispersion of Au and Cu nanoalloy particles with a particle size of 5 nm was prepared. An appropriate amount of the dispersion was used to encapsulate the nanoparticles in 5.0 g of the prepared Ce / Zr-based MOF-808 using an ultrasonic-assisted solvent reflux method, yielding intermediate S2. S2 was dispersed in 100 mL of an ethanol / water mixture (volume ratio 1:1), and 10.0 g of urea was added. After stirring and mixing at 40 °C, the mixture was dried at 60 °C. The resulting solid was then treated under a nitrogen atmosphere at 400 °C to obtain the target catalyst C2. Analysis showed that the catalyst had an Au and Cu loading of 1% (based on total mass), an organic framework particle size of 180 nm, and a C3N4 to Ce / Zr-based MOF-808 mass ratio of 0.1:1 with a particle size of 5 nm.

[0017] Example 3: A dispersion of Ru, Pd, and Ni nanoalloy particles with a particle size of 5 nm was prepared. An appropriate amount of the dispersion was used to encapsulate the nanoparticles in 2.0 g of the prepared Ti / Zr-based MIL-125 using an ultrasonic-assisted solvent reflux method, yielding intermediate S3. S3 was dispersed in 100 mL of ethanol solution, and 5.0 g of melamine was added. After stirring and mixing at 40 °C, the mixture was dried at 60 °C. The resulting solid was then treated under a nitrogen atmosphere at 400 °C to obtain the target catalyst C3. Analysis showed that the catalyst had a Ru, Pd, and Ni loading of 0.5% (based on total mass), an organic framework particle size of 200 nm, and a C3N4 to Ce / Zr-based MOF-808 mass ratio of 0.5:1 with a particle size of 20 nm.

[0018] Example 4: A dispersion of Co and Ag nanoalloy particles with a particle size of 10 nm was prepared. An appropriate amount of the dispersion was used to encapsulate the nanoparticles in 2.0 g of the prepared Zr-based UiO-66 using an ultrasonic-assisted solvent reflux method, yielding intermediate S4. S4 was dispersed in 50 mL of ethanol solution, and 4.0 g of dicyandiamide was added. After stirring and mixing at 40 °C, the mixture was dried at 60 °C. The resulting solid was then treated under a nitrogen atmosphere at 400 °C to obtain the target catalyst C4. Analysis showed that the catalyst had a Co and Ag loading of 5% (based on total mass), an organic framework particle size of 160 nm, a C3N4 to Zr-based UiO-66 mass ratio of 4:1, and a particle size of 10 nm.

[0019] Example 5: A dispersion of Rh nanoparticles with a particle size of 5 nm was prepared. An appropriate amount of the dispersion was used to encapsulate the nanoparticles in 5.0 g of the prepared Ce / Ti-based MIL-125 using an ultrasonic-assisted solvent reflux method, yielding intermediate S5. S5 was dispersed in 200 mL of ethanol solution, and 5.0 g of titanium tetrachloride and 20 mL of water were added. The mixture was stirred and hydrolyzed for 3 h, then centrifuged to obtain a solid. The obtained solid was treated at 300 °C under a nitrogen atmosphere to obtain the target catalyst C5. Analysis showed that the catalyst had a Rh loading of 2% (based on total mass), an organic framework particle size of 150 nm, a TiO2 to Ce / Ti-based MIL-125 mass ratio of 1:1, and a particle size of 5 nm.

[0020] Example 6: A dispersion of Pt nano-alloy particles with a particle size of 2 nm was prepared. An appropriate amount of the dispersion was used to encapsulate the nanoparticles in 5.0 g of the prepared Ce / Zr-based UiO-66 using an ultrasonic-assisted solvent reflux method, yielding intermediate S6. S6 was dispersed in 100 mL of ethanol solution, 3.0 g of tetrabutyl titanate was added, and 10 mL of water was added dropwise. The mixture was stirred and hydrolyzed for 3 h, then centrifuged to obtain a solid. The obtained solid was treated at 300 °C under a nitrogen atmosphere to obtain the target catalyst C6. Analysis showed that the catalyst had a Pt loading of 5% (based on total mass), an organic framework particle size of 200 nm, and a TiO2 to Ce / Zr-based UiO-66 mass ratio of 1:3 with a particle size of 15 nm.

[0021] Example 7: A dispersion of Pt and Ni nano-alloy particles with a particle size of 2 nm was prepared. An appropriate amount of the dispersion was used to encapsulate the nanoparticles in 5.0 g of the prepared Ce / Ti-based MIL-125 using an ultrasonic-assisted solvent reflux method, yielding intermediate S7. S7 was dispersed in 200 mL of ethanol solution, and 1.0 g of Ti-based MIL-125 was added. The mixture was ultrasonically dispersed for 1 h, and the resulting solid was evaporated and treated under a nitrogen atmosphere at 400 °C for 3 h to obtain the target catalyst C7. Analysis showed that the catalyst had a Pt and Ni nano-alloy loading of 3% (based on total mass), an organic framework particle size of 160 nm, and a TiO2 to Ce / Ti-based MIL-125 mass ratio of 1:2 with a particle size of 3 nm.

[0022] Example 8: The catalyst prepared in Examples 1-7 was used in a batch photothermal catalytic reactor with a fatty acid to solvent cyclohexane ratio of 1g:25mL, the catalyst amount was 2% of the fatty acid mass, the reaction temperature was 80℃, the hydrogen partial pressure was 0.2MPa, the xenon lamp light source was 50W, and the reaction time was 2h to obtain the product.

[0023] The present invention, used for photothermal synergistic deoxygenation, can yield high yields of alkane components under appropriate conditions. Specifically, using common oils and fats, an alkane component yield of over 93% can be obtained. The catalyst exhibits good stability and a low deactivation rate. Therefore, the catalysts obtained in Examples 1-7 demonstrate high catalytic activity, high stability, long lifetime, and wide applicability.

[0024] Those skilled in the art will understand that the above-described embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this application. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A hollow multilayer heterostructure catalyst for photothermal deoxygenation of fatty acids, characterized in that: The inner layer of the catalyst consists of one or more nano-metal particles or alloys selected from Ru, Pd, Au, Pt, Rh, Cu, Ni, Co, and Ag, while the outer layer is a heterojunction formed by a metal-organic framework material and one or two of TiO2 and C3N4.

2. A method for preparing the hollow multilayer heterostructure catalyst for photothermal deoxygenation of fatty acids as described in claim 1, characterized in that... Includes the following steps: Step (1) Prepare nano-metal particles or alloys, and encapsulate the nano-metal particles or alloys in a metal-organic framework material by ultrasound-assisted method; Step (2) Using the corresponding precursor, one or both of TiO2 and C3N4 are loaded onto the outer surface of the metal-organic framework material by self-assembly or impregnation.

3. The preparation method according to claim 2, characterized in that: The loading of the nano-metal particles or alloys is 0.1-10.0 wt% based on the total mass.

4. The preparation method according to claim 2, characterized in that: The metal-organic framework material is one of UiO-66, MOF-808, and MIL-125, with one or more of Zr, Ti, and Ce as the central ions.

5. The preparation method according to claim 2, characterized in that: The mass ratio of one or two of the TiO2 and C3N4 to the metal-organic framework material is 0.1-10:

1.

6. The preparation method according to claim 2, characterized in that: The particle size of the metal-organic framework material is 100-200 nm.

7. The preparation method according to claim 2, characterized in that: The particle size of the TiO2 and C3N4 is 1-20 nm.

8. The preparation method according to claim 2, characterized in that: The precursor of C3N4 is at least one of urea, melamine, and dicyandiamide.

9. The preparation method according to claim 2, characterized in that: The TiO2 is prepared from a precursor through controlled hydrolysis and calcination, or from commercially available anatase titanium dioxide.

10. The preparation method according to claim 8 or 9, characterized in that: The precursor is at least one of titanium tetrachloride, titanium ester, and MIL-125.