Cerium-based bimetallic MOFs hydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention discloses a Ce-based bimetallic MOFs catalyst for hydrogenation of dicyclopentadiene and a preparation method of the Ce-based bimetallic MOFs catalyst, and belongs to the field of advanced nano composite catalytic materials. The preparation method comprises the step of synthesizing Ce-based bimetal MOFs containing variable valence metal Ce and other transition metal at room temperature, wherein the ratio of the two metals is different. Flexible conversion of Ce in different valence states provides an electron transfer station for hydrogenation reaction, and adsorption and activation of MOFs on dicyclopentadiene and hydrogen are effectively improved, so that DCPD hydrogenation performance higher than that of monometal MOFs is shown. In addition, the preparation method is simple in process, mild in condition, controllable in parameter, short in period and suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of cerium-containing compound catalysts and catalytic hydrogenation applications, specifically to a metal-organic framework (MOF) hydrogenation catalyst, its preparation method, and its applications. Background Technology

[0002] Since the beginning of the 21st century, aerospace technology has developed rapidly. Increasing the speed and extending the range of aircraft are significant challenges in aerospace technology development. By increasing the density and volumetric energy of the fuel carried by the aircraft, the power provided by the fuel can be increased, significantly improving flight speed and extending range, thus effectively enhancing aircraft performance. Among these, cyclopentadiene-based high-energy-density hydrocarbon fuels possess numerous advantages such as high energy density, low freezing point, and good stability. They can be used alone or in combination with other fuels and have been widely applied as propellants in the aerospace field. The catalytic hydrogenation of dicyclopentadiene, as a key technology for obtaining high-energy-density hydrocarbon fuels, has received widespread attention. Noble metal-based catalysts exhibit superior activity in dicyclopentadiene hydrogenation, but their poor resistance to toxicity and easy loss during the hydrogenation reaction, coupled with their scarcity and high cost, greatly limit their widespread industrial application. Transition metal catalysts, as effective alternatives to noble metals, have attracted considerable attention.

[0003] Metal-organic frameworks (MOFs), as a novel porous material, possess advantages such as tunable pore structure, diverse and designable topologies, and high-density active sites, making them ideal materials for designing active sites at the molecular level. Chinese patent document CN116903868A, entitled "A Method for Preparing a Rare Earth MOF Catalyst for Dicyclopentadiene Hydrogenation," describes the preparation of single-metal cerium MOFs via an ultrasonic-assisted hydrothermal method. This catalyst exhibits good reactivity with dicyclopentadiene, achieving a conversion rate of up to 100%. However, the reaction temperature of this preparation method remains relatively high (90–120 °C), and due to limitations imposed by the properties of the catalyst's active sites, the conversion rate of dicyclopentadiene (97%) and the selectivity for the dihydrodicyclopentadiene product (91%) cannot reach optimal levels. Summary of the Invention

[0004] The technical problem this invention aims to solve is to improve the conversion rate of dicyclopentadiene and the selectivity for dihydrodicyclopentadiene products. By modifying the composition of the active sites and the catalytic mechanism of the catalyst, and optimizing the synthesis conditions of MOFs, a low-cost cerium-based bimetallic MOF catalyst with simple process, mild conditions, and controllable parameters, and its preparation method, is developed to achieve excellent catalytic activity and cycle stability for the hydrogenation of dicyclopentadiene.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a cerium-based bimetallic MOF catalyst, the cerium-based bimetallic MOF catalyst comprising: cerium, a doped transition metal, and a carboxylic acid organic ligand, wherein the cerium and the doped transition metal are chemically bonded to the carboxylic acid organic ligand.

[0006] The doped transition metal is selected from Fe, Co, Ni, Cu or Zn;

[0007] Preferably, the doped transition metal is Cu, Ni, or Co;

[0008] More preferably, the doped transition metal is Cu or Ni.

[0009] The carboxylic acid organic ligand is selected from one or more of phenyl carboxylic acid organic ligands, biphenyl carboxylic acid organic ligands, and nitrogen-containing heterocyclic carboxylic acid organic ligands, with or without substituents, such as pyromellitic acid, 2-aminoterephthalic acid, 2-nitroterephthalic acid, 2-bromoterephthalic acid, 2-fluoroterephthalic acid, 2-sulfonic acid terephthalic acid, 2-hydroxyterephthalic acid, 2,5-dihydroxyterephthalic acid, 2,5-dichloro-2,5-dibenzoic acid, 2,5-pyrazine dicarboxylic acid, 2,5-pyridine dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, terephthalic acid, etc.

[0010] Preferably, the carboxylic acid organic ligand is selected from one or more of pyromellitic acid, 2-aminoterephthalic acid, 2-fluoroterephthalic acid, 2-hydroxyterephthalic acid, or 2,5-dihydroxyterephthalic acid;

[0011] More preferably, the carboxylic acid organic ligand is pyromellitic acid, 2-aminoterephthalic acid, or 2-hydroxyterephthalic acid.

[0012] Furthermore, the molar ratio of the doped transition metal to the cerium is (0.25–6):1;

[0013] Preferably, the molar ratio of the doped transition metal to cerium is (0.5–5):1;

[0014] More preferably, the molar ratio of the doped transition metal to the cerium is (1.5 to 4.5):1.

[0015] Furthermore, the molar ratio of the sum of the doped transition metal and the cerium to the carboxylic acid organic ligand is 1:(0.1-6);

[0016] Preferably, the molar ratio of the sum of the doped transition metal and the cerium to the carboxylic acid organic ligand is 1:(0.3-3);

[0017] More preferably, the molar ratio of the sum of the doped transition metal and the cerium to the carboxylic acid organic ligand is 1:(0.5 to 1.5).

[0018] Furthermore, the cerium-based bimetallic MOF catalyst has a three-dimensional straw bale structure.

[0019] In a second aspect, the present invention provides a method for preparing a cerium-based bimetallic MOF catalyst, the method comprising the following steps:

[0020] Cerium salt, doped transition metal salt, and carboxylic acid organic ligand were mixed with N,N-dimethylformamide; a small molecule regulator was added, and small molecule alcohol and deionized water were selectively added. The mixture was stirred and reacted at a temperature of 0–100 °C. The resulting solid was separated, washed, and dried to obtain a cerium-based bimetallic MOF catalyst.

[0021] Furthermore, the cerium salt is a cerium-containing nitrate, such as cerium nitrate, cerium nitrate hexahydrate, etc.

[0022] Furthermore, the concentration of the cerium salt is 0.01–0.03 mol / L (concentration relative to DMF).

[0023] Furthermore, the doped transition metal salt is selected from one or more nitrates or hydrochlorides containing iron, cobalt, nickel, copper, and zinc, such as copper nitrate trihydrate, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, ferric nitrate nonahydrate, zinc nitrate hexahydrate, copper chloride dihydrate, nickel chloride hexahydrate, cobalt chloride hexahydrate, ferric chloride hexahydrate, and zinc chloride hexahydrate.

[0024] Preferably, the doped transition metal salt is copper nitrate trihydrate, nickel nitrate hexahydrate, or cobalt nitrate hexahydrate;

[0025] More preferably, the doped transition metal salt is copper nitrate trihydrate or nickel nitrate hexahydrate.

[0026] Furthermore, the carboxylic acid organic ligand is selected from one or more of carboxylic acid organic ligands containing or without substituents, biphenyl carboxylic acid organic ligands, and nitrogen-containing heterocyclic carboxylic acid organic ligands, such as pyromellitic acid, 2-aminoterephthalic acid, 2-nitroterephthalic acid, 2-bromoterephthalic acid, 2-fluoroterephthalic acid, 2-sulfonic acid terephthalic acid, 2-hydroxyterephthalic acid, 2,5-dihydroxyterephthalic acid, 2,5-dichloro-2,5-pyrazine dicarboxylic acid, 2,5-pyridine dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, terephthalic acid, etc.

[0027] Preferably, the carboxylic acid organic ligand is selected from one or more of pyromellitic acid, 2-aminoterephthalic acid, 2-fluoroterephthalic acid, 2-hydroxyterephthalic acid, or 2,5-dihydroxyterephthalic acid;

[0028] More preferably, the carboxylic acid organic ligand is pyromellitic acid, 2-aminoterephthalic acid, or 2-hydroxyterephthalic acid.

[0029] Furthermore, the molar ratio of the doped transition metal salt to the cerium salt is (0.25–6):1;

[0030] Preferably, the molar ratio of the doped transition metal salt to the cerium salt is (0.5–5):1;

[0031] More preferably, the molar ratio of the doped transition metal salt to the cerium salt is (1.5 to 4.5):1.

[0032] Further, the molar ratio of the carboxylic acid organic ligand to the sum of the doped transition metal salt and the cerium salt is at least 0.1, 0.2, and 0.3, and at most 3, 3.5, 4, 4.5, 5, 5.5, and 6;

[0033] Preferably, the molar ratio of the sum of the doped transition metal salt and the cerium salt to the carboxylic acid organic ligand is 1:(0.3-3);

[0034] More preferably, the molar ratio of the sum of the doped transition metal salt and the cerium salt to the carboxylic acid organic ligand is 1:(0.5 to 1.5).

[0035] Preferably, the reaction temperature is 10–50°C;

[0036] More preferably, the reaction temperature is 20–35°C.

[0037] Furthermore, the small molecule regulator is selected from C1-C6 amines, C1-C6 organic ammonium acids, and ammonia, such as triethylamine, n-butylamine, ammonium formate, and ammonia.

[0038] Preferably, the amine small molecule modifier is triethylamine;

[0039] The role of small molecule regulators is to promote the deprotonation process of carboxylic acid organic ligands, accelerate crystallization, and thus lower the reaction temperature.

[0040] Furthermore, the concentration of the small molecule regulator is 0.05–0.5 mol / L (relative to DMF);

[0041] Preferably, the concentration of the small molecule regulator is 0.1–0.3 mol / L (relative to DMF).

[0042] Furthermore, the small molecule alcohol is a C1 to C4 alcohol, such as ethanol, methanol, ethylene glycol, propanol, etc.

[0043] Preferably, the small molecule alcohol is ethanol;

[0044] The role of the small molecule alcohol and deionized water is to adjust the morphology and structure of the crystal.

[0045] Furthermore, the reaction time is 30 min to 48 h;

[0046] Preferably, the reaction time is 12 to 24 hours.

[0047] Furthermore, the drying conditions include a temperature of 0–60°C and a time of 10–48 hours.

[0048] Preferably, the order of addition of the cerium salt, the doped transition metal salt, and the carboxylic acid organic ligand is as follows: the cerium salt and the doped transition metal salt are added to N,N-dimethylformamide, stirred and mixed, and then the carboxylic acid organic ligand is added to the above solution, stirred and mixed.

[0049] A third aspect of the present invention provides the application of the aforementioned cerium-based bimetallic MOFs catalyst in the hydrogenation of dicyclopentadiene, comprising the following steps: contacting dicyclopentadiene with the cerium-based bimetallic MOFs catalyst in a reactor in the presence of a solvent; introducing hydrogen gas to carry out a hydrogenation reaction.

[0050] Furthermore, the reactor is a fixed-bed reactor or a batch reactor.

[0051] Furthermore, the solvent is selected from cyclohexane, methanol, n-heptane, or ethanol, and the amount used is 10 to 100 times the mass of dicyclopentadiene.

[0052] Furthermore, the mass ratio of the cerium-based bimetallic MOF catalyst to dicyclopentadiene is (0.1–3):(2–20);

[0053] Preferably, the mass ratio of the cerium-based bimetallic MOF catalyst to dicyclopentadiene is (0.3–2):2;

[0054] More preferably, the mass ratio of the cerium-based bimetallic MOF catalyst to dicyclopentadiene is (0.6–1.5):2.

[0055] Furthermore, the hydrogenation reaction is carried out at a pressure of 0.5–4 MPa, a stirrer speed of 200–1000 rpm / min, a reaction temperature of 50–150 °C, and a reaction time of 5–20 h.

[0056] Preferably, the hydrogenation reaction is carried out at a pressure of 1-3 MPa, a stirrer speed of 400-800 rpm / min, a reaction temperature of 80-140°C, and a reaction time of 8-15 h.

[0057] More preferably, the hydrogenation reaction is carried out at a pressure of 2 to 2.5 MPa, a stirrer speed of 600 to 800 rpm / min, a reaction temperature of 100 to 120°C, and a reaction time of 10 to 12 h.

[0058] Through the above technical solution, the present invention has the following beneficial effects:

[0059] 1. By selecting specific bimetals and organic ligands, bimetallic MOFs with diverse and tunable active sites were prepared. In the catalytic reaction, the electronegativity difference between cerium and the doped transition metal promotes the transfer of electrons from cerium to the doped transition metal, which enhances the adsorption capacity and catalytic performance of the metal active sites, effectively improves the adsorption and activation of dicyclopentadiene and hydrogen by MOFs, thereby improving the hydrogenation performance and cycle stability of the catalyst.

[0060] 2. Carboxylic acid organic ligands can adjust the pore size of MOF materials, thereby better matching the size of the target reactants and increasing the adsorption capacity of the target reactants;

[0061] 3. The addition of amine-based small molecule regulators can effectively promote the crystal growth of MOFs, reduce the reaction temperature, and allow the reaction to proceed at room temperature under mild conditions.

[0062] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0063] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0064] Figure 1 This is a scanning electron microscope image of (Cu4Ce1)3-BTC2 obtained in Example 1 of the present invention.

[0065] Figure 2 This is a scanning electron microscope image of Ce-BTC obtained in Comparative Example 1 of this invention.

[0066] Figure 3 The image shown is a transmission electron microscope (TEM) line scan of (Cu2Ce1)3-BTC2 obtained in Example 2 of this invention.

[0067] Figure 4 The image shows the XRD pattern of (Cu4Ce1)3-BTC2 obtained in Example 1 of this invention. Detailed Implementation

[0068] The present invention will be further described below with reference to specific embodiments. These embodiments are only some, not all, of the present invention. Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in the present invention can be purchased commercially or prepared by existing methods.

[0069] Example 1

[0070] 130.3 mg (0.3 mmol) of cerium nitrate hexahydrate and 289.8 mg (1.2 mmol) of copper nitrate trihydrate were added to 100 mL of N,N-dimethylformamide and stirred at room temperature for 10 min to obtain a clear and transparent solution. 210 mg (1 mmol) of trimesic acid was added to the mixed solution and stirred at room temperature for 10 min. Then, 65 mL of anhydrous ethanol, 6.5 mL of deionized water and 2.5 mL of triethylamine were added, and the mixture was stirred at 30 °C for 12 h. After the reaction was completed, the resulting mixture was centrifuged and washed twice with N,N-dimethylformamide, twice with ethanol and twice with deionized water. The mixture was then freeze-dried for 72 h to obtain a cerium-based bimetallic MOF catalyst with a copper to cerium site ratio of 4:1, denoted as (Cu4Ce1)3-BTC2.

[0071] Example 2

[0072] 217.1 mg (0.5 mmol) of cerium nitrate hexahydrate and 241.6 mg (1 mmol) of copper nitrate trihydrate were added to 100 mL of N,N-dimethylformamide and stirred at room temperature for 5 min to obtain a clear and transparent solution. 210 mg (1 mmol) of trimesic acid was added to the mixed solution and stirred at room temperature for 10 min. Then, 50 mL of anhydrous ethanol, 10 mL of deionized water and 2 mL of ammonium formate were added. The mixture was stirred at 50 °C for 5 h. After the reaction was completed, the resulting mixture was centrifuged and washed twice with N,N-dimethylformamide, twice with ethanol and twice with deionized water. The mixture was then freeze-dried for 72 h to obtain a cerium-based bimetallic MOF catalyst with a copper to cerium site ratio of 2:1, denoted as (Cu2Ce1)3-BTC2.

[0073] Example 3

[0074] 434.2 mg (1.0 mmol) of cerium nitrate hexahydrate and 120.8 mg (0.5 mmol) of copper nitrate trihydrate were added to 100 mL of N,N-dimethylformamide and stirred at room temperature for 10 min to obtain a clear and transparent solution. 210 mg (1 mmol) of trimesic acid was added to the mixed solution and stirred at room temperature for 10 min. Then, 50 mL of anhydrous ethanol, 30 mL of deionized water and 3 mL of triethylamine were added, and the mixture was stirred at 25 °C for 12 h. After the reaction was completed, the resulting mixture was centrifuged and washed twice by N,N-dimethylformamide, twice by ethanol and twice by deionized water. The mixture was then freeze-dried for 72 h to obtain a cerium-based bimetallic MOF catalyst with a copper to cerium site ratio of 1:2, denoted as (Cu1Ce2)3-BTC2.

[0075] Example 4

[0076] 86.8 mg (0.2 mmol) of cerium nitrate hexahydrate and 193.3 mg (0.8 mmol) of copper nitrate trihydrate were added to 100 mL of N,N-dimethylformamide and stirred at room temperature for 10 min to obtain a clear and transparent solution. 210 mg (1 mmol) of trimesic acid was added to the mixed solution and stirred at room temperature for 10 min. Then, 65 mL of anhydrous ethanol, 6.5 mL of deionized water and 2.5 mL of triethylamine were added, and the mixture was stirred at 30 °C for 12 h. After the reaction was completed, the resulting mixture was centrifuged and washed twice with N,N-dimethylformamide, twice with ethanol and twice with deionized water. The mixture was then freeze-dried for 72 h to obtain a cerium-based bimetallic MOF catalyst with a copper to cerium site ratio of 4:1, denoted as (Cu4Ce1)4-BTC5.

[0077] Example 5

[0078] 217.1 mg (0.5 mmol) of cerium nitrate hexahydrate and 120.8 mg (0.5 mmol) of copper nitrate trihydrate were added to 100 mL of N,N-dimethylformamide and stirred at room temperature for 10 min to obtain a clear and transparent solution. 420 mg (2 mmol) of trimesic acid was added to the mixed solution and stirred at room temperature for 10 min. Then, 65 mL of anhydrous ethanol, 6.5 mL of deionized water and 2.5 mL of triethylamine were added, and the mixture was stirred at 30 °C for 12 h. After the reaction was completed, the resulting mixture was centrifuged and washed twice with N,N-dimethylformamide, twice with ethanol and twice with deionized water. The mixture was then freeze-dried for 72 h to obtain a cerium-based bimetallic MOF catalyst with a copper to cerium site ratio of 1:1, denoted as (Cu1Ce1)1-BTC2.

[0079] Example 6

[0080] A nickel-containing cerium-based bimetallic MOF catalyst was prepared according to the method in Example 1, except that 348 mg (1.2 mmol) of nickel nitrate hexahydrate was used instead of 289.8 mg (1.2 mmol) of copper nitrate trihydrate to obtain a cerium-based bimetallic MOF catalyst with a nickel to cerium site ratio of 4:1, denoted as (Ni4Ce1)3-BTC2.

[0081] Example 7

[0082] Cerium-based bimetallic MOFs catalysts containing terephthalic acid ligands were prepared according to the method in Example 1, except that 166 mg (1 mmol) of terephthalic acid was used instead of 210 mg (1 mmol) of trimesic acid to obtain a cerium-based bimetallic MOFs catalyst with a copper to cerium site ratio of 4:1, denoted as (Cu4Ce1)3-BTC4.

[0083] Example 8

[0084] The cerium-based bimetallic MOF catalyst was prepared according to the method in Example 1, except that 1.5 mL of ammonia (25% concentration) was used instead of 2.5 mL of triethylamine to obtain a cerium-based bimetallic MOF catalyst with a copper to cerium site ratio of 4:1, denoted as (Cu4Ce1)3-BTC2-1.

[0085] Comparative Example 1

[0086] 651.3 mg (1.5 mmol) of cerium nitrate hexahydrate was added to 100 mL of N,N-dimethylformamide and stirred at room temperature for 10 min to obtain a clear and transparent solution. 210 mg (1 mmol) of trimesic acid was added to the mixed solution and stirred at room temperature for 10 min. Then, 65 mL of anhydrous ethanol, 6.5 mL of deionized water, and 2.5 mL of triethylamine were added. The mixture was stirred at 30 °C for 12 h. After the reaction was completed, the resulting mixture was centrifuged and washed twice with N,N-dimethylformamide, twice with ethanol, and twice with deionized water. Finally, it was freeze-dried for 72 h to obtain the cerium-based MOF catalyst, denoted as Ce-BTC.

[0087] Comparative Example 2

[0088] Copper-based MOFs were prepared according to the method of Comparative Example 1, except that 651.3 mg (1.5 mmol) of cerium nitrate hexahydrate was replaced with 362.4 mg (1.5 mmol) of copper nitrate trihydrate to obtain a copper-based MOF catalyst, denoted as Cu-BTC.

[0089] Comparative Example 3

[0090] Cerium-based bimetallic MOF catalysts were prepared according to the method in Example 1, except that triethylamine was not added. No reaction occurred at 30°C, but a cerium-based bimetallic MOF catalyst with a copper to cerium site ratio of 4:1 was obtained by reacting at 100°C for 12 h, denoted as (Cu4Ce1)3-BTC2-2.

[0091] Test Implementation Examples

[0092] The products obtained in Example 1 and Comparative Example 1 were subjected to scanning electron microscopy (SEM) testing (test conditions: 5 kV, 10 μA). The results are as follows: Figure 1 and Figure 2 As shown, (Cu4Ce1)3-BTC2 and Ce-BTC exhibit straw bale structure and two-dimensional sheet structure, respectively, indicating that the introduction of doped metals changes the crystallization characteristics of MOFs.

[0093] The product obtained in Example 1 above was subjected to EDS line scan analysis, and the results are as follows: Figure 3 As shown, Ce and Cu are uniformly distributed in the product, proving the successful introduction of doped metals into (Cu4Ce1)3-BTC2.

[0094] The product obtained in Example 1 above was characterized by X-ray diffraction (test conditions: wavelength: The result is as follows Figure 4 As shown, the crystal structure of the obtained product is consistent with Cu-BTC.

[0095] Application Examples

[0096] The hydrogenation process of dicyclopentadiene was carried out in a batch high-pressure reactor equipped with a pressure gauge and a magnetic stirrer. Dicyclopentadiene was dissolved in 5 mL of cyclohexane, and a certain mass of cerium-based bimetallic MOF catalyst (the mass ratio of cerium-based bimetallic MOF catalyst to dicyclopentadiene to cyclohexane was 1:2:200) was added. Before heating the reactor, the air in the reactor was purged with nitrogen, and then hydrogen was added to 2 MPa. The stirrer speed was 600 rpm / min, the temperature was 100 °C, and the reaction time was 10 hours. After hydrogenation, the solution was diluted 10 times with cyclohexane.

[0097] The products obtained after the reaction were analyzed by gas chromatography using an Agilent 7890 GC-MS analyzer. Qualitative analysis of the analytes was performed based on the retention times of the chromatographic peaks, and quantification was achieved using the area normalization method to obtain the conversion rate of dicyclopentadiene (DCPD), the selectivity of dihydrodicyclopentadiene (DHDCPD), and the selectivity of tetrahydrodicyclopentadiene (THDCPD). The test procedure was as follows: the syringe and detector temperatures were set to 250℃ and 280℃, respectively; the column was heated from 50℃ to 100℃ at a rate of 20℃ per minute and held for 2 minutes, then heated to 120℃ at a rate of 5℃ per minute and held for 2 minutes.

[0098] Stability testing: Cyclic tests were conducted using the same catalyst, with each cycle lasting 10 hours under the same conditions as described above. After each cycle, the product obtained was analyzed.

[0099] The catalytic hydrogenation performance of dicyclopentadiene is shown in Table 1, and the cycle stability is shown in Table 2.

[0100] Table 1

[0101]

[0102]

[0103] Table 2

[0104]

[0105] As shown in Table 1, the hydrogenation performance results of dicyclopentadiene show that the cerium-based bimetallic MOF exhibits DCPD hydrogenation activity that is much higher than that of monometallic MOFs. The catalytic activity of the cerium-based bimetallic MOFs prepared with the addition of small molecule regulators is much higher than that of the catalyst prepared without the addition of small molecule regulators. This indicates that the cerium-based bimetallic MOFs of the present invention can significantly improve the target product selectivity, catalytic activity and cycle stability of the dicyclopentadiene hydrogenation reaction.

[0106] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0107] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0108] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A cerium-based bimetallic MOF catalyst, comprising: The catalyst comprises cerium, a doped transition metal, and a carboxylic acid organic ligand, wherein the cerium and the doped transition metal are chemically bonded to the carboxylic acid organic ligand; the doped transition metal is selected from Fe, Co, Ni, Cu, or Zn; the carboxylic acid organic ligand is selected from one or more of phenyl carboxylic acid organic ligands containing or without substituents, biphenyl carboxylic acid organic ligands, and nitrogen-containing heterocyclic carboxylic acid organic ligands; the cerium-based bimetallic MOF catalyst has a three-dimensional straw-bag structure.

2. The cerium-based bimetallic MOF catalyst according to claim 1, wherein, The molar ratio of the doped transition metal to cerium is (0.25–6):1; preferably, the molar ratio of the doped transition metal to cerium is (0.5–5):1; more preferably, the molar ratio of the doped transition metal to cerium is (1.5–4.5):

1.

3. The cerium-based bimetallic MOF catalyst according to claim 1, wherein, The carboxylic acid organic ligand is selected from one or more of the following: pyromellitic acid, 2-aminoterephthalic acid, 2-nitroterephthalic acid, 2-bromoterephthalic acid, 2-fluoroterephthalic acid, 2-sulfonic acid terephthalic acid, 2-hydroxyterephthalic acid, 2,5-dihydroxyterephthalic acid, 2,5-dichloro-2,5-dibenzoic acid, 2,5-pyrazine dicarboxylic acid, 2,5-pyridine dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, and terephthalic acid.

4. The cerium-based bimetallic MOF catalyst according to claim 1, wherein, The molar ratio of the sum of the doped transition metals and cerium to the organic carboxylic acid ligand is 1:(0.1-6); preferably, the molar ratio of the sum of the doped transition metals and cerium to the organic carboxylic acid ligand is 1:(0.3-3); more preferably, the molar ratio of the sum of the doped transition metals and cerium to the organic carboxylic acid ligand is 1:(0.5-1.5).

5. A method for preparing a cerium-based bimetallic MOF catalyst, comprising: Cerium salt, doped transition metal salt, and carboxylic acid organic ligand were mixed with N,N-dimethylformamide; a small molecule regulator was added, and small molecule alcohol and deionized water were selectively added. The mixture was stirred and reacted at a temperature of 0–100 °C. The resulting solid was separated, washed, and dried to obtain a cerium-based bimetallic MOF catalyst.

6. The method according to claim 5, wherein, The cerium salt is selected from cerium nitrate and cerium nitrate hexahydrate; the doped transition metal salt is selected from one or more of nitrates or hydrochlorides containing iron, cobalt, nickel, copper, and zinc; the carboxylic acid organic ligand is selected from one or more of carboxylic acid organic ligands with or without substituents, biphenyl carboxylic acid organic ligands, and nitrogen-containing heterocyclic carboxylic acid organic ligands; the small molecule regulator is selected from C1-C6 amines, C1-C6 organic ammonium acids, and ammonia.

7. The method according to claim 5, wherein, The doped transition metal salt is selected from one or more of copper nitrate trihydrate, nickel nitrate hexahydrate, cobalt nitrate hexahydrate, ferric nitrate nonahydrate, zinc nitrate hexahydrate, copper chloride dihydrate, nickel chloride hexahydrate, cobalt chloride hexahydrate, ferric chloride hexahydrate, and zinc chloride hexahydrate; the carboxylic acid organic ligand is selected from one or more of pyromellitic acid, 2-aminoterephthalic acid, 2-nitroterephthalic acid, 2-bromoterephthalic acid, 2-fluoroterephthalic acid, 2-sulfonic acid terephthalic acid, 2-hydroxyterephthalic acid, 2,5-dihydroxyterephthalic acid, 2,5-dichloro-2,5-dibenzoic acid, 2,5-pyrazine dicarboxylic acid, 2,5-pyridine dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, 2,2'-bipyridine-5,5'-dicarboxylic acid, and terephthalic acid.

8. The method according to claim 5, wherein, The concentration of the cerium salt is 0.01–0.03 mol / L (relative to DMF).

9. The method according to claim 5, wherein, The molar ratio of the doped transition metal salt to the cerium salt is (0.25–6):1; preferably, the molar ratio of the doped transition metal salt to the cerium salt is (0.5–5):1; more preferably, the molar ratio of the doped transition metal salt to the cerium salt is (1.5–4.5):

1.

10. The method according to claim 5, wherein, The molar ratio of the sum of the doped transition metal salts and cerium salts to the organic carboxylic acid ligand is 1:(0.1-6); preferably, the molar ratio of the sum of the doped transition metal salts and cerium salts to the organic carboxylic acid ligand is 1:(0.3-3); more preferably, the molar ratio of the sum of the doped transition metal salts and cerium salts to the organic carboxylic acid ligand is 1:(0.5-1.5).

11. The method according to claim 5, wherein, Preferably, the reaction temperature is 10–50°C; more preferably, the reaction temperature is 20–35°C; the reaction time is 30 min–48 h; preferably, the reaction time is 12–24 h.

12. The method according to claim 5, wherein, The small molecule regulator is selected from one or more of triethylamine, n-butylamine, ammonium formate, and ammonia.

13. The method according to claim 5, wherein, The concentration of the small molecule regulator is 0.05–0.5 mol / L, preferably 0.1–0.3 mol / L (relative to DMF).

14. A method for hydrogenating dicyclopentadiene, comprising: Dicyclopentadiene is contacted in a reactor with the cerium-based bimetallic MOFs catalyst according to any one of claims 1 to 4 or the cerium-based bimetallic MOFs catalyst prepared by any one of claims 5 to 13 in the presence of a solvent; hydrogen is introduced to carry out the hydrogenation reaction.

15. The method according to claim 14, wherein, The reactor is a fixed-bed reactor or a batch reactor.

16. The method of claim 14, wherein, The mass ratio of the cerium-based bimetallic MOF catalyst to dicyclopentadiene is (0.1-3):(2-20); preferably, the mass ratio of the cerium-based bimetallic MOF catalyst to dicyclopentadiene is (0.3-2):2; more preferably, the mass ratio of the cerium-based bimetallic MOF catalyst to dicyclopentadiene is (0.6-1.5):

2.

17. The method of claim 14, wherein, The hydrogenation reaction is carried out at a pressure of 0.5–4 MPa, a temperature of 50–150°C, and a time of 5–20 h; preferably, the hydrogenation reaction is carried out at a pressure of 1–3 MPa, a temperature of 80–140°C, and a time of 8–15 h; more preferably, the hydrogenation reaction is carried out at a pressure of 2–2.5 MPa, a temperature of 100–120°C, and a time of 10–12 h.

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