Preparation and application of polyionic liquid anchoring active metal co unit point heterogeneous catalyst

Abstract

The application provides a preparation method of a polyionic liquid anchoring active metal Co unit point heterogeneous catalyst, which comprises the following steps: mixing an ionic liquid with a Co metal salt aqueous solution, taking a purified carbon-based material as a carrier, and performing ionic liquid thermal polymerization treatment in an inert gas atmosphere to obtain a Co-based heterogeneous catalyst. The catalytic performance (activity, selectivity and stability) of the catalyst in a hydroformylation reaction is tested by taking olefins in the range of C6-C12 as a substrate. The results show that the heterogeneous catalyst prepared by the application can realize accurate regulation of the selectivity of aldehydes to alcohols in the hydroformylation reaction according to the adjustment of the amount of the ionic liquid. In addition, the synthesis process of the catalyst is simple, no ligand is needed, the catalytic activity is high, the performance is very stable, the active metal Co site has a low solution loss rate, and accurate regulation of the product aldehyde / alcohol selectivity can be realized.

Description

Technical Field

[0001] This invention relates to a Co-based catalyst, and more particularly to an ionic liquid-anchored active metal Co unit site heterogeneous catalyst and its preparation method, for catalyzing hydroformylation reactions. Background Technology

[0002] Hydroformylation is widely used in the synthesis of aldehydes / alcohols, typically using syngas (H2 and CO) and olefins as feedstocks. It was discovered by Otto Roelen in 1938 during the Fischer-Tropsch synthesis (H. Li, J. Wu, Z. Jiang, J. Ma, VM Zavala, CR Landis, M. Mavrikakis, GW Huber, Science, 2023, 381, 660). To date, the scale of aldehyde production via conventional homogeneous hydroformylation has exceeded 20 million tons, making it one of the most important homogeneous catalytic reactions. Furthermore, the addition of functional organophosphorus ligands, such as phosphine, phosphites, and related compounds, to the hydroformylation reaction can not only reduce the reaction temperature and pressure but also improve the catalytic activity and selectivity of asymmetric isomerization (K. Raghuvanshi, C. Zhu, M. Ramezani, S. Menegatti, EE Santiso, D. Mason, J. Rodgers, ME Janka, M. Abolhasani, ACS Catalysis, 2020, 10, 7535). Nevertheless, the separation and recovery of catalysts and organophosphorus ligands in homogeneous systems remains a challenging problem. Moreover, some Co-based catalysts are converted to black cobalt oxides or lost in the solvent during the reaction, ultimately leading to a decrease in activity. Therefore, the development of heterogeneous catalysts is of great significance for realizing the recycling and regeneration of industrial catalytic reaction processes (W. Alsalahi, AM Trzeciak, 2021, 430, 213732; J. Zhao, Y. He, F. Wang, Y. Yang, W. Zheng, C. Huo, H. Jiao, Y. Yang, Y. Li, X. Wen, Journal of Catalysis, 2021, 404, 244).

[0003] For heterogeneous catalytic systems, overcoming the dissolution and detachment of active metal sites (M, such as Rh, Co, Fe, and Pd) from the support is a key challenge in heterogeneous hydroformylation research (M. Chen, G. Gupta, CWOrdonez, AR Lamkins, CJ Ward, CA Abolafia, B. Zhang, LT Roling, W. Huang, Journal of the American Chemical Society, 2021, 143, 20907). Due to the high spontaneous coordination of metal carbonyl species, under high pressure and strong coordination with H2 and CO, active metal sites readily dissolve in solution to form thermodynamically stable HM(CO)4. These metal sites are lost after cycling, reducing the activity of subsequent catalyst recycling. Compared with expensive Rh catalysts, the development of Co-based catalysts can significantly reduce process costs. However, the high solubility of Co-based catalysts themselves limits their further development (H. Wang, H. Yuan, X. Chen, X. Wang, K. Zhao, F. Shi, The Journal of Physical Chemistry C, 2021, 126, 273). Li et al. found that when using activated carbon-supported Co catalysts for hydroformylation, the solubility of Co was approximately 20 wt% at a reaction temperature of 135 °C and a reaction pressure of 3 MPa, approximately 30 wt% at a reaction pressure of 4 MPa, and even 50 wt% at a reaction pressure of 5 MPa, indicating that the higher the pressure, the greater the solubility of the active metal Co (B. Li, X. Li, K. Asami, K. Fujimoto, Energy & Fuels, 2003, 17, 810). Zhao et al. developed a novel protective agent Co / SiO2 system for the hydroformylation of 1-hexene, demonstrating that the formate species (HCOO-) in the reaction can inhibit the formation of cobalt carbonyl. When the protective agent citric acid was increased from 0 mg to 2 mg, the dissolution rate of the Co site decreased from 34.5% to 2.2% (J. Zhao, Y. He, F. Wang, W. Zheng, C. Huo, X. Liu, H. Jiao, Y. Yang, Y. Li, X. Wen, ACSCatalysis, 2019, 10, 914).Tao et al. used a Rh-sulfonyl phosphorus catalyst to regulate the heterogeneous hydroformylation reaction, forming an oil-based ionic liquid Pickering emulsion by adding emulsifiers and stabilizers. After six cycles of 1-dodecene hydroformylation, the dissolution rate of Co sites was only 0.33% (L. Tao, M. Zhong, J. Chen, S. Jayakumar, L. Liu, H. Li, Q. Yang, Green Chemistry, 2018, 20, 188). However, highly efficient catalysts that can effectively reduce the dissolution rate of active metals in heterogeneous catalytic systems without the use of additional protective agents, emulsifiers, stabilizers, or phosphine ligands are rarely reported. Summary of the Invention

[0004] The purpose of this invention is to address the problem that existing heterogeneous catalysts are prone to loss of active metal sites and cannot be well recycled, and to provide a heterogeneous catalyst with well-recyclable polyionic liquid anchored active metal Co unit sites and its preparation method for use in hydroformylation reactions.

[0005] The present invention discloses a method for preparing a polyionic liquid-anchored active metal Co unit-site heterogeneous catalyst, comprising the following process steps:

[0006] (1) Add the ionic liquid and Co salt to deionized water at the same time and stir thoroughly until both are completely dissolved to obtain a dispersion of the active component.

[0007] The ionic liquid is any one of 1-sulfonated butyl-3-vinylimidazolium hydrogen sulfate, 1-sulfonated butyl-3-allylimidazolium hydrogen sulfate, 1-sulfonated ethyl-3-vinylimidazolium hydrogen sulfate, and 1-sulfonated ethyl-3-allylimidazolium hydrogen sulfate; the Co salt is any one of CoCO3, CoSO4, Co(OAc)2, and hydrated compounds of CoCO3, CoSO4, and Co(OAc)2; and the molar ratio of the ionic liquid to the Co salt is between 1:0.5 and 1:3.0.

[0008] (2) The carbon-based material on the purified surface is dispersed in isopropanol, stirred and mixed thoroughly, and then ultrasonically treated to ensure that the carbon-based carrier is fully dispersed in isopropanol to obtain a carrier dispersion.

[0009] The carbon-based material is selected from any one of carbon nanotubes, nanodiamonds, or hydrothermal carbon, and the amount of isopropanol solvent used is preferably sufficient to fully disperse the carbon-based material. The stirring and mixing rate is 200 rpm to 500 rpm; the ultrasonic treatment time is 10 min to 120 min.

[0010] (3) The obtained active component dispersion is added dropwise to the support dispersion, and stirred at a constant speed until the solvent is completely evaporated to obtain a catalyst precursor initially loaded with Co. The stirring speed is 200 rpm to 500 rpm; the solvent evaporation time is 1 to 2 days. The ratio of active component dispersion to support dispersion is preferably between 0.1 wt% and 5.0 wt% of Co loading.

[0011] (4) The catalyst precursor initially loaded with Co was freeze-dried until the surface moisture was completely removed to obtain the freeze-dried precursor. The freeze-drying temperature was -50℃ to -30℃, the time was 30 min to 120 min, and the freeze-drying process took 0.5 to 1 day.

[0012] (5) The freeze-dried precursor was placed in a tube furnace and calcined under inert gas protection to obtain a polyionic liquid anchored active metal Co unit point heterogeneous catalyst.

[0013] The inert gas can be any one or more of nitrogen, argon, and helium. The calcination process involves a heating rate of 1℃ / min to 5℃ / min, a constant calcination temperature range of 150℃ to 200℃, and a calcination time of 1 to 2 days.

[0014] The mechanism for preparing heterogeneous catalysts in this invention is based on the principles of polymerization and metathesis reactions (strong acid displacing weak acid) of ionic liquids, utilizing the sulfonic acid group (-SO3H) and sulfate group (SO4) in the functionalized ionic liquid. 2- The catalyst anchors the active metal Co site to form Co-OS bonds (anchoring of the active metal site Co); partial dehydration can generate SC bonds, binding the polyionic liquid to the surface of the carbon-based material (overall anchoring of the catalyst active center) and dispersing well on the surface of the carbon-based support. The resulting heterogeneous catalyst can be used in the hydroformylation reaction to effectively improve the selectivity and cycle stability of aldehydes and achieve precise control of the selectivity of aldehydes and alcohols.

[0015] With C6~ C 12 The catalytic performance of the catalyst in the hydroformylation reaction was tested using olefins as substrates. The results showed that the heterogeneous catalyst prepared in this invention, when used in the hydroformylation reaction, can achieve precise control of the selectivity from aldehydes to alcohols by adjusting the amount of ionic liquid. The selectivity of aldehydes is controllable in the range of 0.5% to 90.2%, and the selectivity of alcohols is 0.5% to 74.8%.

[0016] In summary, the heterogeneous catalyst of this invention has a simple synthesis process, requires no ligands, exhibits high catalytic activity and very stable performance, has a low dissolution rate of active metal Co sites, enables precise control of the aldehyde / alcohol selectivity of the product, and simplifies subsequent catalyst separation. The olefin conversion rate remains above 90.0% even after 10 cycles of testing, indicating broad application prospects. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the selective hydroformylation mechanism of the polyionic liquid-anchored active metal Co unit site heterogeneous catalyst of the present invention.

[0018] Figure 2 ADF-STEM image of the polyionic liquid-anchored active metal Co unit site heterogeneous catalyst prepared in Example 1.

[0019] Figure 3 The XRD patterns are those of the polyionic liquid-anchored active metal Co unit site heterogeneous catalysts prepared in Examples 1-4.

[0020] Figure 4 The images show the FT-IR spectra of the polyionic liquid-anchored active metal Co unit point heterogeneous catalysts prepared in Examples 1-4.

[0021] Figure 5 Hydroformylation activity profiles of heterogeneous catalysts anchored to active metal Co unit sites on polyionic liquids with different carbon supports (Reaction conditions: m (catalyst) = 10 mg; V (toluene) = 3 mL; n (1-octene) = 1 mmol 1-octene (0.33 mol / L); p (syngas,H2 / CO = 1: 1) = 7 MPa; T = 160 ℃; t = 24 h, r = 1000 rpm, S / C = 70).

[0022] Figure 6 Aldehyde-alcohol selectivity regulation activity plot for heterogeneous catalysts anchored to the Co unit point with different amounts of ionic liquid (Reaction conditions: m (0 ~ 1.5 CoPIL / CNT) = 10 mg; V (toluene) = 3 mL; n (1-octene) = 1 mmol 1-octene (0.33 mol / L); p (syngas, H2 / CO = 1: 1) = 7 MPa; T = 160 ℃; t = 24 h, r = 1000 rpm, S / C = 70.). Detailed Implementation

[0023] The following specific examples further illustrate the preparation of the polyionic liquid-anchored active metal Co unit-site heterogeneous catalyst of the present invention and its application in catalyzing hydroformylation reactions.

[0024] Example 1

[0025] Take 36 mg of 1-sulfonyl-3-vinylimidazolium hydrogen sulfate and 27 mg of cobalt acetate tetrahydrate, transfer them to a 20 mL sample bottle, add 1 mL of deionized water, stir and mix well to form a pink transparent solution (the molar ratio of ionic liquid to Co element is set to 1:1, denoted as 1.0 CoIL, and the stirring speed is 200 rpm ~ 500 rpm), and label it as solution A;

[0026] Weigh 50 mg of surface-purified multi-walled carbon nanotubes and 3 mL of isopropanol, transfer them to a new sample vial (20 mL), and sonicate to disperse them evenly at a stirring rate of 200 rpm to 500 rpm to obtain a carrier dispersion, labeled as solution B.

[0027] Solution A was added dropwise to solution B, and after mixing, the mixture was placed in a fume hood and stirred under vacuum at room temperature (stirring at a rate of 200 rpm to 500 rpm) until the deionized water and isopropanol solutions were completely evaporated. During the evaporation process, the cations and anions reacted with sp... 2 Carbon surfaces are bonded together through both physical and chemical bonding.

[0028] The air-dried samples were freeze-dried using a freeze dryer (freeze-drying temperature: -50℃ to -30℃, time: 30 min to 120 min, freeze-drying process time: 0.5 to 1 day) to ensure complete removal of water and isopropanol from the precursor surface, resulting in a precursor of 1.0 CoIL / CNT.

[0029] The precursor 1.0 CoIL / CNT was placed in a tube furnace and heated to 190°C at a rate of 1°C / min, and calcined for approximately 20 h to carry out oxygen-free polymerization of the ionic liquid. N2 was used as a protective gas to prevent air from affecting the CoIL polymerization process. The prepared heterogeneous catalyst, after grinding, is designated as 1.0 CoPIL / CNT.

[0030] The ADF-STEM electron microscope image of the catalyst is attached. Figure 2As shown, Co atoms are well dispersed on the CNT surface. In addition to single atoms, a small number of Co clusters were also observed on the CNTs, which are the result of aggregation of the IL polymer during polymerization. This also indicates that both the polyionic liquid and the Co species are well distributed on the CNT surface, and no significant aggregation occurred during synthesis.

[0031] XRD pattern is attached. Figure 3 As shown, the characteristic peaks of Co(OAc)2 and CoSO4 (PDF#16-0304) are distributed in the range of 2θ = 10° to 60°. After supporting the polyionic liquid active metal Co center with a CNT support, the sp in the CNT supported catalyst... 2 Characteristic peaks of Co(OAc)2 and CoSO4 were not found on the carbon surface. Only broad peaks of multi-walled carbon nanotube materials were retained at 26° (0 0 2) and 43° (1 1 1), indicating the uniform loading and dispersion of active metal Co unit sites and the formation of a heterogeneous catalyst anchored by polyionic liquid for active metal Co unit sites.

[0032] In the appendix Figure 4 In the FT-IR spectra, Co(OAc)₂ dissolved in ionic liquids with different stoichiometric ratios—sulfonic acid-based ionic liquids. (700-900 cm⁻¹) -1 The signal between them is caused by the bending vibration of δ(CH). At 1000 cm... -1 Up to 1200 cm -1 The vibrational absorption bands within this range can be attributed to the stretching vibration ν(SO) in sulfate or sulfonate groups. 1425 cm⁻¹ -1 The signal at this location is attributed to the bending vibration of the methyl group. 1550 cm -1 and 1570 cm -1 The signals at this location belong to the ν(C=C) and ν(C=N) stretching vibration modes in the imidazole ring skeleton, respectively. Furthermore, at 1646 cm⁻¹... -1 and 984 cm -1 The signals correspond to the stretching and bending vibrations of C=C in vinyl groups. After loading, the characteristic signals of the ionic liquid weaken, and the C=C signal of vinyl groups completely disappears, indicating that annealing at 190℃ can complete the polymerization of vinyl groups and successfully prepare a polyionic liquid-anchored active metal Co unit site heterogeneous catalyst.

[0033] The 1.0 CoPIL / CNT solution was used for hydroformylation: 10 mg of catalyst, 1 mmol of 1-octene, and 3 mL of toluene were first weighed and added to a high-pressure reactor, followed by 20 mL of the catalyst to initiate a heterogeneous hydroformylation reaction. The reactor was then purged with N2 to remove air, and syngas (H2:CO = 1:1) was added to the reactor to 7 MPa. The reactor was then heated to 160 °C at 1000 rpm for one day. After the reaction, the reaction solution was filtered, and dodecane was added as an internal standard to calculate the conversion, yield, and selectivity of 1-octene hydroformylation. The substrate for hydroformylation was changed to 1-hexene, 1-quinene, 1-dodecene, 2-octene, 5-dodecene, etc., while the rest remained unchanged. The conversion, yield, and selectivity of the catalytic hydroformylation of corresponding alkenes are shown in Table 1. The 1.0 CoPIL / CNT catalytic hydroformylation of C6–C12 alkenes achieved conversions exceeding 88%, with higher conversions for terminal alkenes (over 93%) than for inner alkenes. Conversions for 1-hexene and 1-octene reached over 99.9% and 98.5%, respectively, demonstrating excellent catalytic hydroformylation performance. In the conversion of 1-octene to C9 aldehydes, the yield and selectivity of C9 aldehydes reached 88.9% and 90.2%, respectively, indicating excellent aldehyde production rate and good selectivity.

[0034] Following the 1.0 CoPIL / CNT catalytic hydroformylation reaction of 1-octene described above, the catalyst can be regenerated through simple washing, centrifugation, and drying steps and used in the next cycle experiment (as shown in Table 2). The study found that after 10 cycles, the conversion of 1-octene still exceeded 90%. Specifically, the yield of 1-nonanal increased from 53.1% in the first cycle to 50.4% in the fifth cycle. In the tenth cycle, the yield of 1-nonanal was 46.7%. With increasing reaction cycles, the amount of isomerized octene increased, while the yield of the aldehyde decreased. Subsequently, ICP testing was performed on the reacted solutions to detect Co dissolution loss: the dissolution rates of metallic Co in the solutions after the first, third, fifth, and tenth reactions were 1.4 wt‰, 5.7 wt‰, 1.0 wt‰, and 1.3 wt‰, respectively, all less than the 1.00 wt% Co dissolution loss. This indicates that the generated Co-OS bonding effectively anchors the active metallic Co unit sites, preventing it from being forcibly coordinated by H2 and CO to form H(CO). n The species effectively prevents the dissolution of active metal Co, demonstrating the excellent cycling stability of the catalyst. Even after 10 tests, the 1.0 CoPIL / CNT catalyst can still continue to the next round of cycling tests.

[0035]

[0036]

[0037] Example 2

[0038] The pure carbon nanotube support in Example 1 was replaced with nanodiamond, while the rest of the process remained identical to that in Example 1. The resulting heterogeneous catalyst, after grinding, was expressed as 1.0 CoPIL / UDD. The XRD pattern of this heterogeneous catalyst is attached. Figure 3 As shown.

[0039] The same method as in Example 1 was used for the hydroformylation reaction with 1.0 CoPIL / UDD, and the conversion, yield, and selectivity of 1-octene hydroformylation were calculated, as shown in the figure. Figure 5 As shown.

[0040] Example 3

[0041] The pure carbon support in Example 1 was replaced with nano-hydrothermal carbon, while the rest remained identical to Example 1. The resulting heterogeneous catalyst, after grinding, was expressed as 1.0 CoPIL / HTC. The XRD pattern of this heterogeneous catalyst is attached. Figure 3 As shown:

[0042] In the XRD pattern, the characteristic peaks of Co(OAc)2 and CoSO4 (PDF#16-0304) are distributed in the range of 2θ = 10° to 60°. After loading with different carbon-based supports, the sp... 2 The carbon surface retained the signals of the (-1 1 4) and (1 1 4) crystal planes of CoSO4, but no characteristic peaks of cobalt acetate were found. Particularly on the CNT surface, when the stoichiometry of the ionic liquid to cobalt acetate was less than 0.5, a small portion of the (-1 1 4) and (1 1 4) crystal planes of CoSO4 were still observed. Further increasing the stoichiometry to above 1.0, the crystal planes disappeared, with only broad peaks of carbon material retained at 26° (0 0 2) and 43° (1 1 1), indicating that CNTs can serve as an ideal carbon-based support for forming active gold unit sites of Co, while using UDD and HTC supports would generate some CoSO4 sites.

[0043] The same method as in Example 1 was used for the hydroformylation reaction with 1.0 CoPIL / HTC, and the conversion, yield, and selectivity of 1-octene hydroformylation were calculated, as shown in the figure. Figure 5 As shown:

[0044] In the catalytic hydroformylation performance tests of different carbon-based supports, the pure carbon-based supports (CNT, UDD, HTC) all showed a hydroformylation performance of less than 8%, and their post-reaction products were all isooctene, indicating that pure carbon-based supports do not possess hydroformylation catalytic activity. Even at 7 MPa and 160 °C, due to the imidazole ring and sp... 2 Strong π-π complexation, CS bonding, and Co-OS bonding between carbon atoms collectively stabilize and anchor the active metal Co sites. The aldehyde yield of 1-octene catalyzed by 1.0 CoPIL / CNT was 88.7%, with a selectivity of 90.2%. When using 1.0 CoPIL / HTC and 1.0 CoPIL / UDD as catalysts, 4% and 21% of nonanol were detected, respectively. This is likely because the CNT support possesses a larger surface area and the flexibility of its hollow two-dimensional structure, which facilitates better dispersion of the active metal Co sites in the polyionic liquid, making it superior to the HTC and UDD supports.

[0045] Example 4

[0046] The amount of 1-sulfonated butyl-3-vinylimidazolium hydrogen sulfate in Example 1 was adjusted to 0 mg, 18 mg, 54 mg, and 72 mg, while the rest remained identical to that in Example 1. The prepared heterogeneous catalysts, after grinding, were represented as 0 CoPIL / CNT, 0.5 CoPIL / CNT, 1.5 CoPIL / CNT, and 2.0 CoPIL / CNT, respectively. The XRD and FT-IR spectra of this catalyst are attached. Figure 3 , 4 As shown:

[0047] In the XRD pattern, changing the amount of 1-sulfonyl-3-vinylimidazolium hydrogen sulfate ionic liquid altered the crystal structure after loading. When the stoichiometry of the ionic liquid to cobalt acetate was less than 0.5, a small portion of the (-1 1 4) and (1 1 4) crystal planes of CoSO4 could still be observed. Further increasing the stoichiometry to above 1.0 caused the characteristic crystal planes of CoSO4 to disappear, with only broad peaks of carbon material remaining at 26° (002) and 43° (111), indicating the formation of Co-OS bonds between the active metal Co unit sites.

[0048] In the infrared spectrum, 1425 cm⁻¹ -1 The signal at 1550 cm⁻¹ is attributed to the bending vibration of the methyl group, and the signal weakens as the ionic liquid ratio increases from 0.5 CoIL to 2.0 CoIL. -1 and 1570 cm -1 The signals at these locations belong to the stretching vibration modes of C=C and C=N in the imidazole ring skeleton, respectively, and become stronger as the stoichiometry of the ionic liquid increases. Furthermore, the C=C in the vinyl group is at 1646 cm⁻¹.-1 and 984 cm -1 The tensile and bending vibration signals at the loading point are stronger. However, after loading, the characteristic signals of the ionic liquid weaken. In all CoPIL / CNT catalysts with different ionic liquid ratios (0.5 – 2.0), the C=C signal of vinyl groups completely disappears, indicating the completion of vinyl polymerization during the anaerobic polymerization process at 190℃ and the formation of polyionic liquid anchored active metal Co unit sites.

[0049] The hydroformylation test method of Example 1 was used, except that the 1.0 CoPIL / CNT catalyst was replaced with 0CoPIL / CNT, 0.5 CoPIL / CNT, 1.5 CoPIL / CNT, and 2.0 CoPIL / CNT (adjusting the amount of ionic liquid), while the rest remained identical to Example 1. The conversion, yield, and selectivity of the hydroformylation of 1-octene were calculated, and the results are as follows: Figure 6 As shown:

[0050] With increasing ionic liquid dosage, the selectivity of C9 alcohol to C9 aldehyde products can be controlled. Using a 0 CoPIL / CNT catalyst, the selectivity of C9 alcohol products is 74.8%. Increasing the ionic liquid dosage gradually decreases the selectivity of C9 alcohol products. When using a 0.5 CoPIL / CNT catalyst, the selectivity of C9 alcohol products decreases significantly to 10.1%. Using 1.0 and 1.5 CoPIL / CNT catalysts, the selectivity of C9 alcohol products decreases to less than 0.5%. The selectivity of C9 aldehydes is exactly the opposite of that of alcohols. With increasing ionic liquid dosage, the C9 aldehyde product gradually increases, with the selectivity rising from 19.3% to 90.2%. Further increasing the ionic liquid dosage causes the C9 aldehyde product to gradually disappear (<0.5%). This is because the reaction system undergoes a reaction state from homogeneous to multiphase coexistence, and then to completely heterogeneous hydroformylation (the bonding of excess sulfonic acid groups or sulfate ions with Co at a single point saturates the coordination environment of Co). The 1.0 CoPIL / CNT catalyst system enables a completely heterogeneous hydroformylation reaction while maintaining high selectivity for C9 aldehydes (90.2%). In summary, the catalyst of this invention features a simple synthesis process, requires no ligands, exhibits high catalytic activity and excellent stability, has a low dissolution rate at the active metal Co sites, and allows for precise control of the aldehyde / alcohol selectivity of the product.

Claims

1. Use of a polyionic liquid anchored active metal Co single site heterogeneous catalyst in a hydroformylation reaction, characterized in that, The preparation of this heterogeneous catalyst includes the following process steps: (1) Add the ionic liquid and Co salt to deionized water at the same time and stir thoroughly until both are completely dissolved to obtain a dispersion of the active component; the ionic liquid is any one of 1-butyl-3-vinylimidazolium sulfonate, 1-butyl-3-allylimidazolium sulfonate, 1-ethyl-3-vinylimidazolium sulfonate, and 1-ethyl-3-allylimidazolium sulfonate. (2) The carbon-based material on the purified surface is dispersed in isopropanol, stirred and mixed thoroughly, and then ultrasonically treated to ensure that the carbon-based carrier is fully dispersed in isopropanol to obtain a carrier dispersion; the carbon-based material is selected from any one of carbon nanotubes, nanodiamonds or hydrothermal carbon. (3) The obtained active component dispersion is added dropwise to the support dispersion and stirred at a constant speed until the solvent is completely evaporated to obtain a catalyst precursor initially loaded with Co; (4) The catalyst precursor initially loaded with Co was freeze-dried until the surface moisture was completely removed to obtain the freeze-dried precursor. (5) The freeze-dried precursor is placed in a tube furnace and calcined under inert gas protection to obtain a polyionic liquid anchored active metal Co unit point heterogeneous catalyst; the calcination process is as follows: the heating rate is 1℃ / min~5℃ / min, the constant calcination temperature range is 150℃~200℃, and the calcination time is 1~2 days.

2. Use according to claim 1, characterized in that: The molar ratio of the ionic liquid to the Co salt is between 1:0.5 and 1:3.

0.

3. Use according to claim 1, characterized in that: The duration of the ultrasonic treatment is 10 min to 120 min.

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