Preparation method and application of metal supported ligand functionalized rare earth catalyst
By functionalizing the ligand on the Ce-UiO-66 support and synthesizing atomically dispersed metal-supported catalyst, the problems of inactivation and poor stability of traditional catalysts in the dicyclopentadiene hydrogenation reaction are solved, and an efficient and cyclable catalytic effect is achieved.
Patent Information
- Application Number
- CN202411670474.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-02-28
AI Technical Summary
Traditional catalysts have problems of high temperature inactivation and poor cycle stability in catalyzing dicyclopentadiene hydrogenation reaction, making it difficult to achieve efficient and cyclable catalytic effects.
By preparing the ligand-functionalized Ce-UiO-66 support, the Ce-UiO-66 supported metal composite catalyst was synthesized by solvothermal method to ensure direct contact between the metal atoms and the support, and atomic dispersion of metal supported catalysts were achieved.
High-efficiency catalytic and good cycle stability of the hydrogenation reaction of dicyclopentadiene are achieved, and the activity and stability of the catalyst are improved.
Smart Images
Figure CN119524927A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of nano-composite catalytic material preparation technology and dicyclopentadiene hydrogenation application, and specifically relates to the preparation of an atomically dispersed metal-supported ligand-functionalized rare earth metal organic framework (MOFs) catalyst. Background Art
[0002] Dicyclopentadiene (DCPD), the main component of the C5 fraction of petroleum processing byproducts, can be hydrogenated to produce a three-ring bridged tetrahydrodicyclopentadiene (endo-THDCPD), which can be further isomerized to produce exo-THDCPD. Exo-THDCPD is a high-energy liquid fuel with excellent performance and is used to prepare jet propellant (JP-10). It is currently the ideal fuel for modern new hypersonic aircraft with the largest consumption, the widest application, and the best comprehensive performance. Therefore, the catalytic hydrogenation reaction of DCPD has attracted widespread attention as a synthetic reaction with important application value. Among many catalysts, supported catalysts have been recognized as efficient and stable catalysts. The carrier of the supported catalyst is believed to play a key role in the catalytic performance by regulating the electronic state of the active metal and its surrounding microenvironment through the SMSI effect. Specifically, by adjusting the carrier, the chemical microenvironment around the metal is changed, the electron transfer between the metal and the carrier is enhanced, and the electronic state of the metal surface is optimized, thereby enhancing the adsorption capacity and reactivity of the catalyst. However, traditional active metals are mainly based on metal nanoparticles, and the interaction between the support and the metal particles is mainly concentrated at the metal-support interface. Metal atoms that are not in direct contact with the support are not easily modulated, resulting in different atomic coordination environments and electronic structures inside and outside the metal particles. These different catalytic sites lead to different adsorption modes of reactants / intermediates, which affect the catalytic activity. Therefore, further reducing the size of metal particles to the atomic scale - atomic dispersion - can ensure that each metal atom interacts directly with the support, which not only enhances the metal activity, but also increases the utilization of metal atoms, which is more conducive to studying the structure-performance relationship at the atomic level.
[0003] Metal-organic frameworks (MOFs) are emerging porous materials with high specific surface area and tunability. They can fix atomically dispersed active species through -OH on metal oxygen clusters, and have the inherent advantage of stabilizing metals. The microenvironment of guest metals in MOFs can be easily adjusted by modifying MOFs, thereby affecting their electronic structure. In addition, Ce-based MOFs materials benefit from the unique Ce element 3+ / Ce 4+Electronic structure has shown unique advantages in the field of catalysis. Loading metal active components into the Ce-based MOFs framework can improve the atomic utilization of metal components, regulate the dispersion, stability and electron density of catalytic active sites, and synergistically enhance the catalytic performance. In particular, the regulation of organic ligands can affect the heterogeneous structure and chemical properties of Ce-based MOFs and metal components, further regulate the unique interaction between metal active components and Ce-based MOFs heterogeneous interface, and optimize the electronic structure of loaded metal active sites, which is expected to achieve efficient catalytic DCPD hydrogenation performance.
[0004] Compared with the traditional commercial catalyst Raney nickel, its active center is less affected by the carrier, and it is very easy to be over-hydrogenated during the catalytic cycle, causing it to aggregate and deactivate, reducing its catalytic cycle stability. At present, the commonly used Raney nickel hydrogenation catalyst only has single-use performance, cannot achieve cyclic hydrogenation, is prone to spontaneous combustion and difficult to recycle. Therefore, how to prepare Ce-based MOFs-loaded metal composite catalytic materials with high dispersibility, high catalytic activity and high stability is an urgent need for the efficient development of catalytic materials for dicyclopentadiene hydrogenation. Summary of the invention
[0005] The purpose of the present invention is to develop a method for preparing a Ce-UiO-66 supported metal composite catalytic material with simple process and adjustable electronic structure by preparing a ligand-functionalized Ce-UiO-66 carrier, so as to achieve good catalytic activity and cycle stability for DCPD hydrogenation.
[0006] The technical scheme of the present invention is: step 1) adding a monocarboxylic acid regulator to a mixed solution of ammonium cerium nitrate, then introducing different organic ligands, and synthesizing a ligand-functionalized Ce-UiO-66 carrier by a solvothermal method; step 2) uniformly dispersing the ligand-functionalized Ce-UiO-66 carrier in the solution, adding a metal precursor under stirring conditions, and obtaining an atomically dispersed metal-loaded Ce-UiO-66.
[0007] The specific preparation steps are:
[0008] 1) Weigh a certain amount of ammonium cerium nitrate (CAN) and add it to deionized water, and add a certain amount of monocarboxylic acid regulator, stir at room temperature for 1-15 min to completely dissolve CAN, and obtain an orange-yellow clear and transparent solution A, and the concentration of CAN in the solution is 0.001-10 mol / L; add a certain amount of functionalized organic ligand to N,N-dimethylformamide (DMF), stir at room temperature for 5-20 min to completely dissolve the organic ligand, and obtain a clear and transparent colorless solution B, and the concentration of the ligand in the solution is 0.001-10 mol / L; mix solution A and solution B so that the molar ratio of CAN to organic ligand is 0.01-1:0.01-1, stir and react at 30-150 °C for 5 min-12 h, after the reaction is completed, separate the product, wash it with methanol and dry it, and obtain a defect-adjustable and ligand-functionalized Ce-UiO-66 carrier;
[0009] 2) At 25~80 ℃, a certain amount of Ce-UiO-66 carrier was uniformly dispersed in n-pentane, and the concentration of the carrier in the solution was 0.1~1000 g / L. Metal precursor C was added under stirring conditions to obtain a mixed solution D, and the metal loading amount relative to the carrier was 0.1~5 wt%. The mixed solution D was stirred under argon atmosphere to enable the metal to be fully anchored into the Ce-UiO-66 carrier framework. The n-pentane was removed by vacuum to obtain a ligand-functionalized Ce-UiO-66 composite catalyst loaded with metal atoms.
[0010] Furthermore, the molar ratio of CAN to the monocarboxylic acid regulator in the mixed solution A of step 1) is 1:1-50, that is, the monocarboxylic acid regulator added is 1-50 molar equivalents (1-50 eq) relative to ammonium cerium nitrate.
[0011] Furthermore, the monocarboxylic acid regulator described in step 1) includes one of formic acid, acetic acid, trifluoroacetic acid, trimethylacetic acid, propionic acid, alanine, glycine, and phenylalanine; the organic ligand described in step 1) includes one of terephthalic acid, 2-bromoterephthalic acid, 2-hydroxyterephthalic acid, 2-nitroterephthalic acid, trimesic acid, pyromellitic acid, 2-methoxyterephthalic acid, and 2-methylterephthalic acid; the metal precursor described in step 2) includes one of silver nitrate, cobalt acetate, copper acetate, zinc acetate, palladium acetate, ammonium palladium nitrate, iridium chloride hydrate, methoxycyclooctadiene iridium, iridium bromide, manganese chloride, nickel chloride, zinc chloride, potassium chloroplatinate, chloroplatinic acid, and chloroauric acid.
[0012] Preferably, the monocarboxylic acid is adjusted to formic acid; the organic ligand is 2-nitroterephthalic acid; and the metal precursor is methoxycyclooctadiene iridium.
[0013] Furthermore, the drying in step 1) is performed in a vacuum oven at 60-120° C. for 12-24 h.
[0014] Furthermore, the stirring time in step 2) is 1 to 24 h.
[0015] Furthermore, the amount of the metal precursor C added in step 2) is 0.1-5 wt% relative to the theoretical loading amount of the carrier and the active metal component.
[0016] The ligand-functionalized Ce-UiO-66 loaded metal atom composite catalyst prepared as above is applied to the preparation of aviation fuel.
[0017] Furthermore, the Ce-UiO-66 loaded metal atom composite catalyst is applied by weighing the Ce-UiO-66 loaded metal atom composite catalyst powder into a hydrogenation reactor, adding cyclohexane and DCPD, setting the hydrogen pressure and temperature, and centrifuging the catalyst after the reaction to obtain the product high-quality aviation fuel THDCPD. In the synthesis process of Ce-based MOFs of the present invention, a functionalized organic ligand is added to synthesize a Ce-UiO-66 carrier with electronic regulation, and the anchoring effect in the metal organic framework is used to load the atomically dispersed metal active sites into the Ce-UiO-66 carrier to obtain an atomically dispersed metal-loaded ligand-functionalized Ce-UiO-66 composite catalyst for dicyclopentadiene hydrogenation. Compared with traditional carbon material carriers, Ce-UiO-66 material has better anchoring sites and excellent adjustability. The rich organic ligands in Ce-UiO-66 carrier provide the basis for the conditions. Through the functionalization of ligands, the regulation of the carrier's electron transfer ability is achieved, which further affects the electronic structure of Ir active species. Since the electronic structure of Ir is adjusted, the adsorption of substrate molecules and catalyst surfaces during the hydrogenation process of DCPD to prepare high-density aviation fuel THDCPD is promoted, and the reaction is carried out efficiently.
[0018] The advantages of the present invention are: 1) a new type of ligand-functionalized Ce-based MOFs-loaded metal composite catalytic material is developed for the first time to enhance DCPD hydrogenation; 2) the ligand can effectively regulate the Ce in the Ce-UiO-66 carrier 3+ / Ce 4+ ratio, through the regulation of Ce-OM heterostructure, the atomically dispersed Ir active species are further anchored and regulated by the Ce-UiO-66 carrier, realizing the controllable regulation of the electronic state, size and catalytic activity of the Ir metal active component; 3) The preparation method is simple in process, controllable in parameters, short in cycle, and suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1This is a scanning electron microscope photograph of the Ce-UiO-66 carrier obtained in Example 1 of the present invention.
[0020] Figure 2 This is the FTIR graph of the Ce-UiO-66 loaded Ir atomically dispersed species composite catalytic material obtained in Example 1 of the present invention.
[0021] Figure 3 This is a transmission electron microscope photograph of the Ce-UiO-66 loaded Ir atomic dispersed species composite catalytic material obtained in Example 1 of the present invention.
[0022] Figure 4 This is the XRD diagram of the Ce-UiO-66 loaded Ir atomic dispersed species composite catalytic material obtained in Example 1 of the present invention. DETAILED DESCRIPTION
[0023] The technical solution of the present invention is further described below in conjunction with specific implementation methods.
[0024] Example 1
[0025] First, 0.82 g of CAN was added to 2.71 mL of deionized water, and 1.69 mL of anhydrous formic acid regulator (30 eq) was added, and stirred at room temperature for 10 min to obtain solution A. Subsequently, 0.316 g of 2-nitroterephthalic acid was added to 12 mL of DMF and stirred at room temperature for 10 min to obtain solution B. Solution A and solution B were mixed and stirred in an oil bath at 100 °C for 15 min. After the reaction, the product was filtered and separated, washed with methanol, and dried in a vacuum oven at 100 °C for 12 h to prepare a Ce-UiO-66 carrier containing a nitro-functionalized ligand. Then, at room temperature (25 °C), 0.2 g of nitrated Ce-UiO-66 carrier was uniformly dispersed in 8 mL of n-pentane solution, 0.01 g of methoxycyclooctadiene iridium was added, and the mixed solution was stirred for 12 h. The product was vacuum dried to obtain the atomically dispersed Ir-loaded nitrated Ce-UiO-66 composite catalytic material, recorded as Ir@Ce-UiO-66-NO2. Figure 1 From the electron microscope image, we can see that the prepared Ce-UiO-66-NO2 particles are regular octahedrons with a particle size of about 500 nm. Figure 2 The infrared spectrum shows that the functionalization of nitro-containing ligands was successfully achieved in the Ce-UiO-66 carrier. Figure 3 The transmission electron microscope image shows that the Ir species is uniformly loaded on the Ce-UiO-66-NO2 carrier, and no Ir nanoparticles are observed, proving that the Ir species is in an atomically dispersed state. In addition, the XRD diffraction pattern ( Figure 4) It can be seen that the Ir@Ce-UiO-66-NO2 composite material has obvious XRD diffraction peaks at 2θ = 7.1°, 24.7°, 29.5°, etc., indicating that the crystal structure of Ce-UiO-66-NO2 anchoring the Ir active species is not destroyed and has high stability, and there is no diffraction peak of Ir single substance, which proves that the Ir active species is highly dispersed and small in size.
[0026] Catalytic DCPD hydrogenation performance: Weigh 0.02 g of catalyst powder and load it into a hydrogenation reactor. Add 5 mL of cyclohexane and 200 μL of DCPD. Set the hydrogen pressure to 1.5 MPa and keep the temperature at 70 °C for 1.5 h. After the reaction, centrifuge the catalyst and analyze the product by GC-MS liquid chromatography-mass spectrometry. The DCPD conversion rate is 100%, the DHDCPD selectivity is 0.01%, and the THDCPD selectivity is 99.9%.
[0027] Catalytic DCPD cyclic hydrogenation performance: After the hydrogenation, the catalyst was centrifuged, washed with cyclohexane three times, and then redispersed in the hydrogenation reactor. Cyclohexane was added to 5 mL, followed by 200 μL DCPD. The hydrogen pressure was set to 1.5 MPa, and the temperature was kept at 70 °C for 1.5 h. After the reaction, the catalyst was centrifuged and the product was analyzed by GC-MS liquid chromatography-mass spectrometry. After 4 catalytic cycles, the DCPD conversion rate was 100%, the DHDCPD selectivity was 0.01%, and the THDCPD selectivity was 99.9%.
[0028] Example 2
[0029] First, 0.82 g CAN was added to 2.71 mL deionized water, and 2.82 mL anhydrous formic acid regulator (50eq) was added, and the mixture was stirred evenly at room temperature for 15 min to obtain solution A. Subsequently, 0.249 g terephthalic acid was added to 12 mL DMF and stirred at room temperature for 10 min to obtain solution B. Solution A and solution B were mixed, stirred and reacted at 100 °C for 15 min. After the reaction was completed, the product was separated by filtration, washed with methanol and dried in a vacuum oven at 100 °C for 24 h to prepare the Ce-UiO-66 carrier. At room temperature (25 °C), 0.2 g Ce-UiO-66 carrier was evenly dispersed in 8 mL n-pentane solution, 0.01 g methoxycyclooctadiene iridium was added, the mixed solution was stirred for 12 h, and the product was vacuum dried to obtain the atomically dispersed Ir-loaded Ce-UiO-66 composite catalytic material, recorded as Ir@Ce-UiO-66.
[0030] Catalytic DCPD hydrogenation performance: Weigh 0.02 g of catalyst powder and load it into a hydrogenation reactor, add 5 mL of cyclohexane and 200 μL of DCPD, set the hydrogen pressure to 1.5 MPa, and keep the temperature at 70 ℃ for 1.5 h. After the reaction, the catalyst was centrifuged and the product was analyzed by GC-MS liquid chromatography-mass spectrometry. The DCPD conversion rate was 100%, the DHDCPD selectivity was 30.2%, and the THDCPD selectivity was 69.8%.
[0031] Catalytic DCPD cyclic hydrogenation performance: After the hydrogenation, the catalyst was centrifuged, washed with cyclohexane three times, and then redispersed in the hydrogenation reactor. Cyclohexane was added to 5 mL, followed by 200 μL DCPD. The hydrogen pressure was set to 1.5 MPa, and the temperature was kept at 70 °C for 1.5 h. After the reaction, the catalyst was centrifuged and the product was analyzed by GC-MS liquid chromatography-mass spectrometry. After 4 catalytic cycles, the DCPD conversion rate was 100%, the DHDCPD selectivity was 37.7%, and the THDCPD selectivity was 62.3%.
[0032] Example 3
[0033] First, 0.82 g of CAN was added to 2.71 mL of deionized water, and 3.59 mL of anhydrous formic acid regulator (40 eq) was added, and stirred at room temperature for 10 min to obtain solution A. Subsequently, 0.249 g of 2-bromoterephthalic acid was added to 12 mL of DMF and stirred at 30 °C for 15 min to obtain solution B. Solution A and solution B were mixed and stirred at 100 °C for 20 min. After the reaction, the product was filtered and separated, washed with methanol and dried in a vacuum oven at 100 °C for 12 h to prepare a Ce-UiO-66 carrier containing bromine functionalized ligands. Then, at room temperature (25 °C), 0.2 g of brominated Ce-UiO-66 carrier was uniformly dispersed in 8 mL of n-pentane solution, 0.01 g of methoxycyclooctadiene iridium was added, and the mixed solution was stirred for 12 h. The product was vacuum dried to obtain atomically dispersed Ir-loaded brominated Ce-UiO-66 composite catalytic material, recorded as Ir@Ce-UiO-66-Br.
[0034] Catalytic DCPD hydrogenation performance: Weigh 0.02 g of catalyst powder and load it into a hydrogenation reactor. Add 5 mL of cyclohexane and 200 μL of DCPD. Set the hydrogen pressure to 1.5 MPa and keep the temperature at 70 °C for 1.5 h. After the reaction, centrifuge the catalyst and analyze the product by GC-MS liquid chromatography-mass spectrometry. The DCPD conversion rate is 100%, the DHDCPD selectivity is 6.5%, and the THDCPD selectivity is 93.5%.
[0035] Catalytic DCPD cyclic hydrogenation performance: After the hydrogenation, the catalyst was centrifuged, washed with cyclohexane three times, and then redispersed in the hydrogenation reactor. Cyclohexane was added to 5 mL, followed by 200 μL DCPD. The hydrogen pressure was set to 1.5 MPa, and the temperature was kept at 70 °C for 1.5 h. After the reaction, the catalyst was centrifuged and the product was analyzed by GC-MS liquid chromatography-mass spectrometry. After 4 catalytic cycles, the DCPD conversion rate was 100%, the DHDCPD selectivity was 7.1%, and the THDCPD selectivity was 92.9%.
[0036] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the thinking and principle of the present application should be included within the scope of the claims of the present application.
Claims
1. A method for preparing a metal-supported ligand-functionalized rare earth catalyst, characterized in that: The preparation steps are as follows: 1) Weigh a certain amount of ammonium cerium nitrate (CAN) and add it to deionized water, and add a certain amount of monocarboxylic acid regulator, stir at room temperature for 1-15 min to completely dissolve CAN, and obtain an orange-yellow clear and transparent solution A, and the concentration of CAN in the solution is 0.001-10 mol / L; add a certain amount of functionalized organic ligand to N,N-dimethylformamide (DMF), stir at room temperature for 5-20 min to completely dissolve the organic ligand, and obtain a clear and transparent colorless solution B, and the concentration of the ligand in the solution is 0.001-10 mol / L; mix solution A and solution B so that the molar ratio of CAN to organic ligand is 0.01-1:0.01-1, stir and react at 30-150 °C for 5 min-12 h, after the reaction is completed, separate the product, wash it with methanol and dry it, and obtain a defect-adjustable and ligand-functionalized Ce-UiO-66 carrier; 2) At 25~80 ℃, a certain amount of Ce-UiO-66 carrier was uniformly dispersed in n-pentane, and the concentration of the carrier in the solution was 0.1~1000 g / L. Metal precursor C was added under stirring conditions to obtain a mixed solution D, and the metal loading amount relative to the carrier was 0.1~5 wt%. The mixed solution D was stirred under argon atmosphere to enable the metal to be fully anchored into the Ce-UiO-66 carrier framework. The n-pentane was removed by vacuum to obtain a ligand-functionalized Ce-UiO-66 composite catalyst loaded with metal atoms.
2. The preparation method according to claim 1, characterized in that: The molar ratio of ammonium cerium nitrate to monocarboxylic acid regulator in the mixed solution A of step 1) is 1:1-50.
3. The preparation method according to claim 1, characterized in that: The monocarboxylic acid regulator described in step 1) includes one of formic acid, acetic acid, trifluoroacetic acid, trimethylacetic acid, propionic acid, alanine, glycine, and phenylalanine; the organic ligand described in step 1) includes one of terephthalic acid, 2-bromoterephthalic acid, 2-hydroxyterephthalic acid, 2-nitroterephthalic acid, trimesic acid, pyromellitic acid, 2-methoxyterephthalic acid, and 2-methylterephthalic acid; the metal precursor C described in step 2) includes one of silver nitrate, cobalt acetate, copper acetate, zinc acetate, palladium acetate, ammonium palladium nitrate, iridium chloride hydrate, methoxycyclooctadiene iridium, iridium bromide, manganese chloride, nickel chloride, zinc chloride, potassium chloroplatinate, chloroplatinic acid, and chloroauric acid.
4. The preparation method according to claim 1 or 3, characterized in that: The monocarboxylic acid is adjusted to formic acid; the organic ligand is 2-nitroterephthalic acid; and the metal precursor C is methoxycyclooctadiene iridium.
5. The preparation method according to claim 1, characterized in that: The drying in step 1) is carried out in a vacuum oven at 60-120°C for 12-24 hours.
6. The preparation method according to claim 1, characterized in that: The stirring time in step 2) is 1 to 24 h.
7. The preparation method according to claim 1, characterized in that: The amount of the metal precursor C added in step 2) is 0.1-5 wt% relative to the theoretical loading amount of the carrier and the active metal component.
8. The ligand-functionalized Ce-UiO-66 supported metal atom composite catalyst prepared according to any one of claims 1 to 7 is used in the preparation of aviation fuel.
9. The use of the Ce-UiO-66 supported metal atom composite catalyst according to claim 8, characterized in that: The Ce-UiO-66 metal atom-loaded composite catalyst powder was weighed and loaded into a hydrogenation reactor, cyclohexane and DCPD were added, the hydrogen pressure and temperature were set, and the catalyst was centrifuged after the reaction to obtain the product aviation fuel THDCPD.