Supported hydroformylation catalyst, preparation method and method for synthesizing pentacaraldehyde

Abstract

The invention provides a supported hydroformylation catalyst, a preparation method and a method for synthesizing pentacaraldehyde, and relates to the technical field of heterogeneous catalysis of homogeneous catalysts. The structural form of the supported hydroformylation catalyst provided by the invention is Rh (at) P-N / AC, Rh is an active center of the catalyst, and P-N / AC is a carrier; the AC is activated carbon; the structural formula of the P-N organic ligand is shown as a formula I to a formula IV. The supported hydroformylation catalyst provided by the invention can realize catalytic circulation of noble metals and phosphine ligands, and has high activity and C2 selectivity.

Description

Technical Field

[0001] This invention relates to the field of homogeneous catalyst heterogeneity technology, and particularly to a PN organic ligand, a supported hydroformylation catalyst, a preparation method, and a method for synthesizing pentacarbonaldehyde. Background Technology

[0002] 4-Acetyloxy-2-methyl-2-butenal (abbreviated as pentacarbonal), also known as 4-Acetyloxy-2-methyl-2-Butenal, is a chemically synthesized product with the following chemical structural formula:

[0003]

[0004] Pentaldehyde is an intermediate of vitamin A and plays an important role in the synthesis of vitamin A. Therefore, the synthesis process of pentaldehyde has long been a research hotspot.

[0005] Currently, the preparation process of aldehydes mainly uses cobalt-based and rhodium-based homogeneous / heterogeneous catalysts. The reaction conditions of cobalt-based catalytic systems are relatively harsh, requiring high temperature and high pressure. Homogeneous Rh-P catalytic systems have the advantages of mild reaction conditions and high reaction activity, and have been widely studied in industry.

[0006] Patent US10913055 B2 As a phosphine ligand, it catalyzes hydroformylation reactions at 70-90℃ and 14-20 bar pressure, achieving a conversion rate greater than 61.9% and an n / i ratio in the range of 1.09-1.91. (Patent US 6362354B1 is mentioned.) Using phosphine ligands and Rh(acac)(CO)₂ as the central metal, this catalyst catalyzes the hydroformylation of butadiene, achieving highly efficient conversion at 95°C and 0.69 MPa. Patent CN 115739184A utilizes a specific combination of phosphine-based monophosphine and phosphine-based bisphosphine ligands as ligands. Through a PN structure with strong π-electron acceptance, it enhances the electron-accepting ability and steric effect of Rh species, catalyzing the hydroformylation of isobutylene dimer, thus improving the catalytic activity of hydroformylation and achieving a conversion rate greater than 95%. However, homogeneous catalytic systems have inherent drawbacks, such as difficult catalyst regeneration and recycling, poor selectivity, and complex separation and purification processes. The addition of organophosphine ligands to the catalytic system places higher demands on production equipment, significantly increasing production costs and posing new challenges to the ecological environment, severely restricting large-scale industrial production.

[0007] Patent CN 115739146 A discloses a method for preparing a heterogeneous hydroformylation catalyst. The active metal Rh is prepared as a ferromagnetic Fe3O4@SiO2-NH2-Rh intermediate. Polyvinylpyrrolidone is added as a stabilizer to prepare a Fe3O4@SiO2-NH2-Rh@SiO2 core-shell catalyst. The pores are etched with sodium hydroxide, and the catalyst is applied to the hydroformylation of olefins in FCC light gasoline and FT synthetic distillate oils. Patent CN 115041232A discloses a method for preparing a heterogeneous hydroformylation catalyst. This catalyst consists of a phosphine-containing organic porous copolymer supporting Rh metal. The phosphine-containing organic porous copolymer is a copolymer of at least one monodentate phosphite and at least one bidentate phosphite monomer. This catalyst exhibits excellent catalytic performance in the hydroformylation of mixed olefins and good reactivity towards C1. Patent CN 113856721B proposes a Rh-CoO-NNTs heterogeneous catalyst, exhibiting a synergistic effect between Rh-CoO and Rh-NNTs. Its catalytic activity and stability surpass those of the Rh-CoO catalyst, demonstrating good catalytic activity and stability in the hydroformylation conversion of cycloolefins. Patent CN 114931961A provides a method for preparing a supported rhodium-based catalyst, using rhodium supported on a transition metal phosphide as the catalyst and adding a bisphosphine ligand. This catalytic system exhibits high catalytic activity and stability, with a C1 selectivity exceeding 87.6% and a conversion rate exceeding 99%. However, the catalytic system still does not achieve P-ligand recycling. Summary of the Invention

[0008] In view of this, the present invention aims to provide a supported hydroformylation catalyst, a preparation method, and a method for synthesizing pentacarbon aldehydes. The supported hydroformylation catalyst provided by the present invention can realize the catalytic cycle of noble metals and phosphine ligands, and has high activity and C2 selectivity.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a supported hydroformylation catalyst, wherein the catalyst has the structural form Rh@PN / AC, wherein Rh is the active center of the catalyst, PN / AC is the support; AC is activated carbon; and the PN organic ligand has one of the structural formulas shown in Formulas I-IV:

[0010]

[0011] Preferably, the particle size of the Rh is 1-3 nm; the loading of the Rh is 2-5%; and the activated carbon is in powder form with a specific surface area of ​​800-1000 μm. 2 / g.

[0012] Preferably, the preparation method of the PN organic ligand is as follows: 2-bromocarbazole and bipyridine bromide are coupled to obtain N-bipyridinecarbazole intermediate, and then the N-bipyridinecarbazole intermediate is coupled with diphenylphosphine chloride to obtain the PN organic ligand.

[0013] This invention also provides a method for preparing the supported hydroformylation catalyst described in the above technical solution, comprising the following steps:

[0014] (1) The PN organic ligand and the Rh precursor described in the above technical solution are pre-coordinated to obtain a mixed solution;

[0015] (2) Add activated carbon to the mixture obtained in step (1), sonicate to disperse the carrier, then use impregnation method to obtain solid catalyst sample, and finally perform rotary evaporation and drying to obtain solid sample;

[0016] (3) The solid sample obtained in step (2) is subjected to hydrogenation reduction roasting and carbonization at 500-700℃, with a heating rate of 5-10℃ / min, to obtain the target product.

[0017] Preferably, the molar ratio of Rh element to PN organic ligand in the Rh precursor of step (1) is (0.5-10):1.

[0018] Preferably, the precursor of Rh is hydrated rhodium chloride or acetylacetone carbonyl rhodium.

[0019] Preferably, the pre-coordination reaction conditions in step (1) are room temperature, normal pressure, and a reaction time of 2-5 hours.

[0020] Preferably, the roasting and carbonization time in step (3) is 2 hours.

[0021] The present invention also provides a method for synthesizing pentacarbon aldehydes, wherein the supported Rh@PN / AC catalyst described in the above technical solution is used for the hydroformylation reaction of but-3-ene-1,2-diyl diacetate to prepare pentacarbon aldehydes.

[0022] Beneficial technical effects:

[0023] 1. The preparation of pentacarbon aldehydes using the heterogeneous catalyst of the present invention can achieve a conversion rate of over 98% and a C2 selectivity of 80%, which are significantly improved compared with industrial production data.

[0024] 2. Using the heterogeneous catalyst of this invention, no additional organophosphorus ligands are required, the catalytic system is successfully cycled, and it has good stability, which meets the requirements of green production for enterprises. Attached Figure Description

[0025] Figure 1The XRD pattern of the catalyst 5% Rh@PN / AC in Example 1;

[0026] Figure 2 HRTEM image (a) and mapping image (b) of the catalyst 5% Rh@PN / AC in Example 1;

[0027] Figure 3 This is a reaction mechanism diagram for the preparation of pentacarbonaldehyde by the catalytic hydroformylation of 3,4-diacetyl-1-butene in Example 2. Detailed Implementation

[0028] Traditional hydroformylation heterogeneous catalysts are prepared using activated carbon as a support with the addition of phosphine ligands. However, the weak Rh-C interaction in these catalysts leads to significant Rh loss, preventing them from reaching industrial application levels. Introducing N and P elements can effectively improve the properties of activated carbon, but traditional physical doping methods suffer from uneven element distribution, weak interaction strength, easy loss, and the need for additional organic ligands. The catalyst obtained by the method disclosed in this invention is rich in uniformly dispersed PN functional groups on its surface. Furthermore, the multidentate coordination between Rh and PN atoms achieves high dispersion and efficient utilization of Rh atoms, ensuring the catalyst's fundamental activity and stability. By selecting specific organic ligands, no additional P ligands are required, successfully achieving the catalytic cycle of the organic ligands and exhibiting high C2 selectivity.

[0029] Based on the above principles, this invention provides a supported hydroformylation catalyst. In this invention, the rhodium atom is the active center. The key technology lies in the selection and immobilization of the PN organic ligand, and appropriate electronic and structural adjustments are needed to achieve high activity and C2 selectivity of the Rh atom.

[0030] In this invention, the catalyst has the structure Rh@PN / AC, where Rh is the active center of the catalyst and PN / AC is the support; AC is activated carbon; the PN organic ligand has one of the structural formulas shown in Formulas I-IV, preferably a compound having the structural formula shown in Formula I:

[0031]

[0032] In some embodiments, the particle size of the Rh is preferably 1-3 nm; the loading of the Rh is preferably 2-5%; the activated carbon is in powder form and the specific surface area is preferably 800-1000 μm. 2 / g. Rh particle size in the range of 1-3nm can significantly improve the basic activity and stability of the Rh central metal; the use of activated carbon plays an important role in the hydroformylation reaction. Activated carbon can promote or enhance CO adsorption and inhibit CO dissociation. The abundant pore structure in activated carbon is conducive to the diffusion and mass transfer of reactants and products, making it more suitable for the hydroformylation reaction of olefins.

[0033] In some embodiments, the PN organic ligand is prepared by: coupling 2-bromocarbazole and bipyridine bromide to obtain an N-bipyridinecarbazole intermediate, and then coupling the N-bipyridinecarbazole intermediate with diphenylphosphine chloride to obtain the PN organic ligand.

[0034] To synthesize For example, the specific operation of the preparation method of the PN organic ligand is as follows:

[0035]

[0036] Step 1: Coupling of 2-bromocarbazole with bipyridine: 2-bromocarbazole (5.39 g, 22 mmol), 1,3-dimethyl-2-imidazolinone (50 mL), bipyridine bromide (5 g, 20 mmol), cuprous iodide (0.19 g, 1 mmol), and lithium tert-butoxide (1 equiv., 1.76 g, 22 mmol) were added sequentially to a 150 mL sealed tube. The mixture was stirred at 150 °C for 16 hours, and the reaction progress was monitored by TLC (EA:PE = 1:10, Rf = 0.3). After the reaction was completed, the 1,3-dimethyl-2-imidazolinone solution was removed by vacuum distillation at 100 °C to obtain a brown oily substance. 25 mL of ethyl acetate and 200 mL of purified water were added to the system, and the mixture was stirred at room temperature for 15 min. A large amount of light yellow solid precipitated out. The solid was filtered to obtain a large amount of crude product, and column chromatography was used to separate the pure product as N-bipyridinecarbazole intermediate.

[0037] Step 2: Synthesis of PN ligands: Under nitrogen protection, at -78℃, n-butyllithium (1.1 equiv., 0.66 mL, 2.5 mol / L in cyclohexane) was slowly added dropwise to 10 mL of anhydrous tetrahydrofuran containing the N-bipyridine carbazole intermediate (0.6 g, 1.5 mmol) prepared in Step 1 using a syringe. After the addition was complete, the mixture was kept at -78℃ with stirring for 3 h. Then, 2 mL of tetrahydrofuran solution containing diphenylphosphine chloride (0.366 g, 1.65 mmol) was added dropwise. After the addition was complete, the hydrazine condenser was turned off, and the temperature was slowly raised to room temperature with stirring overnight. After the reaction was completed, an appropriate amount of methanol was added to terminate the reaction. The organic solvent was removed by vacuum distillation, and the mixture was extracted with ethyl acetate and purified water. The organic layer was concentrated to obtain the crude product, which was then purified by column chromatography (EA:PE = 1:10) to obtain the pure PN organic ligand.

[0038] The present invention also provides a method for preparing the supported hydroformylation catalyst described above, comprising the following steps:

[0039] (1) The PN organic ligand and the Rh precursor described in the above technical solution are pre-coordinated to obtain a mixed solution;

[0040] (2) Add activated carbon to the mixture obtained in step (1), sonicate to disperse the carrier, then use impregnation method to obtain solid catalyst sample, and finally perform rotary evaporation and drying to obtain solid sample;

[0041] (3) The solid sample obtained in step (2) is subjected to hydrogenation reduction roasting and carbonization at 500-700℃, with a heating rate of 5-10℃ / min, and roasted for 2h to obtain the target product.

[0042] In this invention, the molar ratio of Rh element to PN organic ligand in the Rh precursor is preferably (0.5-10):1, more preferably 4:1. Within this range, the Rh atom dispersion can be guaranteed, achieving the maximum atom utilization rate, while avoiding the reduction of the catalyst's basic activity caused by excessively strong binding between the metal and the support.

[0043] In this invention, the precursor of Rh is preferably hydrated rhodium chloride or rhodium acetylacetonate carbonyl, more preferably rhodium acetylacetonate carbonyl; in this invention, the PN organic ligand and the precursor of Rh are pre-mixed in an ethanol solution and stirred at room temperature for 2-5 hours for pre-coordination.

[0044] In this invention, the activated carbon is further subjected to a crushing pretreatment before being added to the mixture obtained in step (1), and the mesh size of the activated carbon after crushing is 100-300 mesh; in this invention, the activated carbon is preferably graphitized activated carbon; the ultrasonic treatment time is preferably 2 hours; the drying temperature is preferably 60°C, and the drying time is preferably 8-12 hours.

[0045] In this invention, the hydrogenation reduction calcination process is a key step in the preparation of the catalyst. While reducing Rh, the PN organic ligand is carbonized to obtain a specific PN group. The control of the reduction temperature and heating rate is crucial; too low a temperature will result in incomplete carbonization and loss of the ligand and central metal, while too high a temperature will cause the central metal to agglomerate, reducing metal utilization. The preferred carbonization calcination temperature is 550°C.

[0046] This invention also provides a method for synthesizing pentacarbonaldehyde, which involves using the supported hydroformylation catalyst in the hydroformylation reaction of but-3-ene-1,2-diyl diacetate to prepare pentacarbonaldehyde. Specifically, the supported hydroformylation catalyst, raw materials 3,4-diacetyl-1-butene, and toluene are added to a high-pressure reactor, and syngas is introduced to carry out the hydroformylation reaction. In this invention, the syngas is a syngas mixture of CO and H2; the hydroformylation reaction temperature is 60-120℃, preferably 100℃; the hydroformylation reaction time is 4-20 h, preferably 10 h; and the hydroformylation reaction pressure is 5-12 MPa, preferably 8 MPa.

[0047] To better understand this invention, the following embodiments further illustrate its content, but the scope of this invention is not limited to the embodiments described below. All technologies implemented based on the above description of this invention are covered within the scope of protection intended by this invention. Unless otherwise stated, the raw materials and reagents used in the following embodiments are commercially available products or can be prepared by known methods.

[0048] The raw materials are described below:

[0049] The activated carbon was purchased from Xi'an Kaili New Material Co., Ltd., in powder form, with a specific surface area of ​​800-1000 μm. 2 / g;

[0050] Rhodium chloride hydrate and rhodium acetylacetone carbonyl were purchased from Shaanxi Kaida Chemical Co., Ltd., with a purity of 99%.

[0051] 1-bromo-9H-carbazole, 6-bromo-2,2-bipyridine, diphenylphosphine chloride, and 3,4-diacetyl-1-butene were all purchased from Aladdin, AR purity.

[0052] The synthesis gas has a CO:H2 molar ratio of 1:1, a purity of 99.9%, and an S content of <1ppm. It was prepared in-house.

[0053] All solvents were of analytical grade.

[0054] Example 1

[0055] Preparation of PN organic ligands

[0056] Step 1: Coupling of 2-bromocarbazole with bipyridine: 2-bromocarbazole (5.39 g, 22 mmol), 1,3-dimethyl-2-imidazolinone (50 mL), 6-bromo-2,2-bipyridine (5 g, 20 mmol), cuprous iodide (0.19 g, 1 mmol), and lithium tert-butoxide (1 equiv., 1.76 g, 22 mmol) were added sequentially to a 150 mL sealed tube. The mixture was stirred at 150 °C for 16 hours, and the reaction progress was monitored by TLC (EA:PE = 1:10, Rf = 0.3). After the reaction was completed, the 1,3-dimethyl-2-imidazolinone solution was removed by vacuum distillation at 100 °C to obtain a brown oily substance. 25 mL of ethyl acetate and 200 mL of purified water were added to the system, and the mixture was stirred at room temperature for 15 min. A large amount of light yellow solid precipitated out. The solid was filtered to obtain a large amount of crude product, and column chromatography was used to separate the pure product as an N-bipyridine-carbazole intermediate.

[0057] Step 2: Synthesis of PN ligands: Under nitrogen protection, at -78℃, n-butyllithium (1.1 equiv., 0.66 mL, 2.5 mol / L in cyclohexane) was slowly added dropwise to 10 mL of anhydrous tetrahydrofuran containing the N-bipyridine carbazole intermediate (0.6 g, 1.5 mmol) prepared in Step 1 using a syringe. After the addition was complete, the mixture was kept at -78℃ with stirring for 3 h. Then, 2 mL of tetrahydrofuran solution containing diphenylphosphine chloride (0.366 g, 1.65 mmol) was added dropwise. After the addition was complete, the hydrazine condenser was turned off, and the temperature was slowly raised to room temperature with stirring overnight. After the reaction was completed, an appropriate amount of methanol was added to terminate the reaction. The organic solvent was removed by vacuum distillation, and the mixture was extracted with ethyl acetate and purified water. The organic layer was concentrated to obtain the crude product, which was then purified by column chromatography (EA:PE = 1:10) to obtain the pure PN organic ligand.

[0058] Preparation of 5% Rh@PN / AC catalyst A

[0059] (1) Rhodium in acetylacetone carbonyl rhodium and PN organic ligand prepared in Example 1 were premixed in an ethanol solution at a molar ratio of 2:1 and stirred at room temperature for 4 hours to obtain a mixture;

[0060] (2) After adding 1g of activated carbon to the mixture obtained in step (1), ultrasonic treatment was performed for 2 hours to disperse the carrier. Then, the solid catalyst sample was obtained by impregnation method, and rotary evaporation and drying at 60℃ for 10 hours were performed to obtain the solid sample.

[0061] (3) The solid sample was reduced under a hydrogen atmosphere and calcined at 550°C for 2 hours with a heating rate of 5°C / min to obtain the target product.

[0062] The obtained 5% Rh@PN / AC catalyst was characterized by XRD. Figure 1It can be seen that the catalyst support is an amorphous carbon support, and the PN ligand treatment did not change the support structure. The absence of Rh characteristic peaks in the XRD pattern confirms the high fraction of Rh in this catalyst.

[0063] Depend on Figure 2 The mapping spectrum of the catalyst shows that four elements, CNPRh, were detected on the catalyst surface. The PN ligand was uniformly dispersed on the surface of the activated carbon support, and the rhodium was uniformly dispersed without agglomeration.

[0064] Example 2

[0065] Catalytic hydroformylation of 3,4-diacetyl-1-butene to prepare pentacarbonaldehyde:

[0066] Take 1 mmol of catalyst A prepared in Example 1, 0.1 mol of raw material 3,4-diacetyl-1-butene, and 10 ml of toluene, add them to a 100 ml high-pressure reactor, introduce synthesis gas, and react at 10 MPa and 100 °C for 10 hours.

[0067] Sampling analysis showed that the raw material conversion rate was 99.0% and the C2 selectivity was 80.4%.

[0068] Example 3

[0069] Preparation of 5% Rh@PN / AC catalyst B

[0070] The preparation of catalyst A is the same as in Example 1, except that in step (1), rhodium acetylacetone carbonyl is replaced with an equal amount of hydrated rhodium chloride.

[0071] Example 4

[0072] Preparation of 5% Rh@PN / AC catalyst C

[0073] The preparation of catalyst A is the same as in Example 1, except that the molar ratio of acetylacetone carbonyl rhodium to PN organic ligand in step (1) is replaced with 5:1.

[0074] Example 5

[0075] Preparation of 5% Rh@PN / AC catalyst D

[0076] The preparation of catalyst A is the same as in Example 1, except that the molar ratio of acetylacetone carbonyl rhodium to PN organic ligand in step (1) is replaced with 1:1.

[0077] Example 6

[0078] Preparation of 5% Rh@PN / AC catalyst E

[0079] The preparation of catalyst A is the same as in Example 1, except that the molar ratio of acetylacetone carbonyl rhodium to PN organic ligand in step (1) is replaced with 0.5:1.

[0080] Example 7

[0081] Preparation of 5% Rh@PN / AC catalyst F

[0082] The preparation of catalyst A is the same as in Example 1, except that the calcination temperature in step (3) is 700°C.

[0083] Example 8

[0084] Preparation of 5% Rh@PN / AC catalyst G

[0085] The preparation of catalyst A is the same as in Example 1, except that the heating rate in step (3) is 10℃ / min.

[0086] Comparative Example 1

[0087] Preparation of 5% Rh / AC catalyst

[0088] The preparation of catalyst A is the same as in Example 1, except that PN organic ligand is not added in step (1).

[0089] Comparative Example 2

[0090] Preparation of pentacarbonaldehyde by catalytic hydroformylation of 3,4-diacetyl-1-butene

[0091] Same as Example 2, except that catalyst A is replaced with catalyst 5%Rh / AC from Comparative Example 1.

[0092] Sampling analysis revealed that the reaction process is an stoichiometric reaction. This indicates that catalytic cycling cannot be achieved without the addition of phosphine ligands, and only stoichiometric reactions can occur. However, the Rh@PN / AC catalyst achieves catalytic cycling without the need for additional phosphine ligands, and exhibits high activity and C2 selectivity. This demonstrates the heterogeneity of organophosphine ligands, which is of significant practical importance for reducing production costs, mitigating environmental pollution, and achieving green catalysis.

[0093] Example 9

[0094] Preparation of pentacarbonaldehyde by catalytic hydroformylation of 3,4-diacetyl-1-butene

[0095] Same as Example 2, except that catalyst A was replaced with catalyst B. Sampling analysis showed a feed conversion rate of 98.0% and a C2 selectivity of 79.3%.

[0096] Example 10

[0097] Preparation of pentacarbonaldehyde by catalytic hydroformylation of 3,4-diacetyl-1-butene

[0098] Same as Example 2, except that catalyst A was replaced with catalyst C. Sampling analysis showed a feed conversion rate of 97.9% and a C2 selectivity of 77.9%.

[0099] Example 11

[0100] Preparation of pentacarbonaldehyde by catalytic hydroformylation of 3,4-diacetyl-1-butene

[0101] Same as Example 2, except that catalyst A was replaced with catalyst D. Sampling analysis showed a feed conversion rate of 98.4% and a C2 selectivity of 78.1%.

[0102] Example 12

[0103] Preparation of pentacarbonaldehyde by catalytic hydroformylation of 3,4-diacetyl-1-butene

[0104] Same as Example 2, except that catalyst A was replaced with catalyst E. Sampling analysis showed a feed conversion rate of 98.7% and a C2 selectivity of 76.7%.

[0105] Example 13

[0106] Preparation of pentacarbonaldehyde by catalytic hydroformylation of 3,4-diacetyl-1-butene

[0107] Same as Example 2, except that catalyst A was replaced with catalyst F. Sampling analysis showed a feed conversion rate of 92.3% and a C2 selectivity of 78.4%.

[0108] Example 14

[0109] Preparation of pentacarbonaldehyde by catalytic hydroformylation of 3,4-diacetyl-1-butene

[0110] Same as Example 2, except that catalyst A was replaced with catalyst G. Sampling analysis showed a feed conversion rate of 91.2% and a C2 selectivity of 76.8%.

[0111] Test case

[0112] Testing the cycle performance of the catalyst

[0113] The preparation of pentacarbonaldehyde was achieved through the catalytic hydroformylation of 3,4-diacetyl-1-butene. Catalyst A underwent its first cycle, and the following treatment was performed: centrifugation to separate the catalyst, followed by washing with water (10 ml × 3), washing with toluene (10 ml × 3), and drying at 60°C. The feed conversion rate was 99.1%, and the C2 selectivity was 80.2%.

[0114] Catalyst A was recycled for the second time. The feed conversion rate was 98.6%, and the C2 selectivity was 79.9%.

[0115] Catalyst A was recycled for the third time. The feed conversion rate was 98.2%, and the C2 selectivity was 79.8%.

[0116] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A supported hydroformylation catalyst, characterized in that, The catalyst has the structure Rh@PN / AC, where Rh is the active center of the catalyst and PN / AC is the support; AC is activated carbon; and the PN organic ligand has one of the structural formulas shown in Formulas I-IV.

2. The supported hydroformylation catalyst according to claim 1, characterized in that, The Rh particle size is 1-3 nm; the Rh loading is 2-5%; the activated carbon is in powder form with a specific surface area of ​​800-1000 μm. 2 / g.

3. The supported hydroformylation catalyst according to claim 1, characterized in that, The method for preparing the PN organic ligand is as follows: 2-bromocarbazole and bipyridine bromide are coupled together to obtain an N-bipyridinecarbazole intermediate, and then the N-bipyridinecarbazole intermediate is coupled together with diphenylphosphine chloride to obtain the PN organic ligand.

4. The method for preparing the supported hydroformylation catalyst according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Pre-coordinate the PN organic ligand and the Rh precursor to obtain a mixture; (2) Add activated carbon to the mixture obtained in step (1), sonicate to disperse the carrier, then use impregnation method to obtain solid catalyst sample, and finally perform rotary evaporation and drying to obtain solid sample; (3) The solid sample obtained in step (2) is subjected to hydrogenation reduction roasting and carbonization at 500-700℃, with a heating rate of 5-10℃ / min, to obtain the target product.

5. The preparation method according to claim 4, characterized in that, In step (1), the molar ratio of Rh element to PN organic ligand in the Rh precursor is (0.5-10):

1.

6. The preparation method according to claim 4 or 5, characterized in that, The precursor of Rh is hydrated rhodium chloride or acetylacetone carbonyl rhodium.

7. The preparation method according to claim 5, characterized in that, The pre-coordination reaction conditions described in step (1) are room temperature, normal pressure, and a reaction time of 2-5 hours.

8. The preparation method according to claim 5, characterized in that, The roasting and carbonization time in step (4) is 2 hours.

9. A method for synthesizing pentacarbon aldehydes, characterized in that, The supported Rh@PN / AC catalyst according to any one of claims 1-3 is used for the hydroformylation reaction of but-3-ene-1,2-diyl diacetate to prepare pentacarbonaldehyde.

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