High-molecular polymer supported noble metal monatomic catalyst

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a high-molecular polymer supported noble metal monatomic catalyst. The catalyst takes a non-polar, weak-polar, moderate-polar or polar high-molecular polymer as a carrier; the active component is selected from at least one noble metal single atom of ruthenium, rhodium, palladium, iridium, platinum or cobalt; the catalyst is prepared by an impregnation-reduction method. The prepared noble metal racemization catalyst has a reaction interface reaching up to 200-1100m < 2 > / g, has good compatibility with a biological enzyme catalyst, can be used in the fields of environment and energy, and is especially suitable for being used as an in-situ racemization catalyst to be combined with an enzyme for dynamic kinetic resolution to prepare an enantiomer pure product. The preparation process is simple, the noble metal loading capacity is less than or equal to 1wt%, the production cost can be effectively reduced, and the method has remarkable industrial application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a noble metal single-atom catalyst supported on a polymer. Background Art

[0002] In 2011, Academician Zhang Tao et al. first proposed the concept of "single-atom catalyst". As a new type of catalyst, single-atom catalysts (SACs) can maximize the atomic utilization rate, significantly reduce the cost of noble metal catalysts, and are easy to separate and recycle. Since then, a research boom on single-atom catalysts has been set off at home and abroad. SACs loaded with noble metals such as Pd, Pt, Ru, Rh, and Ir have been widely used to address environmental and energy issues. However, the preparation methods of single-atom catalysts are generally complex. For example, the atomic layer deposition (ALD) method has high equipment costs and low yields, making it difficult to scale up; the high-temperature pyrolysis method requires subsequent treatment after pickling, with a high metal loss rate; these methods have problems such as relatively high production costs, low yields, complex operations, and difficulty in industrial production. Therefore, it is particularly important to develop and design a preparation method for single-atom catalysts that is simple in synthesis method, controllable in metal type and its loading amount, and capable of large-scale production.

[0003] The present invention proposes an innovative solution for preparing noble metal single-atom catalysts. By using an inexpensive polymer as a carrier and a simple preparation method, SACs are prepared. The prepared SACs can not only be used in the fields of environment and energy, but also be used as an in-situ racemization catalyst in combination with enzymes for dynamic kinetic resolution (DKR) to prepare chiral molecules.

[0004] Chiral molecules (such as chiral alcohols, amines, and their derivatives) are key intermediates in the synthesis of pharmaceuticals and fine chemicals. In traditional preparation methods, enzymatic kinetic resolution (KR) is limited by a 50% theoretical yield, while the asymmetric reduction method is difficult to promote due to the high cost of chiral precursors. Dynamic kinetic resolution (DKR) achieves a 100% theoretical yield by coupling the racemization reaction with the resolution step. However, the existing technology faces bottlenecks such as high costs of noble metal catalysts, poor compatibility between metals and enzymes, and insufficient reaction interfaces. The noble metal catalyst prepared by using a polymer as a carrier in this innovative solution, or a metal single-atom catalyst, is combined with an immobilized lipase to construct a DKR system for the preparation of chiral compounds. The use of a polymer carrier to prepare a single-atom racemization metal catalyst not only avoids the inhibition of enzyme activity by metals, but also greatly reduces the amount of noble metals (such as ruthenium and palladium) used through single-atomization, significantly reducing costs; at the same time, the immobilized enzyme and the noble metal racemization catalyst of the present invention are fully dispersed in the organic solvent, greatly improving the catalytic interface, solving the problems of mismatch between the racemization and resolution reactions and complex processes in the traditional DKR system, and providing an efficient and economical new path for the green large-scale production of chiral drugs.

[0005] Obtaining an efficient and cost-effective DKR reaction system is crucial for preparing chiral products. Addressing this challenge requires the preparation of low-cost noble metal racemization catalysts. This invention aims to prepare metal single-atom catalysts using polymers as supports, resulting in low-cost racemization catalysts with large reaction interfaces and good enzyme compatibility.

[0006] Polymer-supported noble metal single-atom catalysts are unique metal catalysts. The metal components on the polymer exist as single atoms, without forming metal nanoparticles or clusters. This allows each metal atom to serve as an active site, achieving near-100% metal atom utilization. This significantly reduces the amount of supported metal elements and addresses industrial production costs. Each noble metal atom serves as an active site, each capable of independently catalyzing a reaction, resulting in higher catalytic activity than nanoparticle and cluster catalysts. Summary of the Invention

[0007] In order to significantly improve the metal catalytic efficiency and reduce the catalyst cost, the present invention aims to provide a polymer-supported noble metal single-atom catalyst to solve the technical problems of the existing technology of complex preparation methods of single-atom catalysts, high production costs, and difficulty in large-scale production.

[0008] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0009] The present invention discloses for the first time a high molecular polymer supported noble metal single atom catalyst, and the high molecular polymers that can be used include: polyvinyl chloride, polyether, polystyrene, polyester, polyamide, polyurethane, silicone rubber, polyethylene, polycarbonate, polypropylene, polyethylene terephthalate, polyester fiber, polyphenylene sulfide, etc. Due to the large number of types, for convenience, they are classified according to the surface polarity of the polymers into non-polar high molecular polymers, weak polar high molecular polymers, medium polar high molecular polymers, and polar high molecular polymers. Because different reactions require different surface microenvironments, polymers of different polarities are just right for different reactions. Classification according to the surface polarity of the polymers is more convenient during use. The metal compound used is mainly a noble metal compound, selected from at least one of cobalt sulfate, ruthenium sulfate, rhodium sulfate, palladium sulfate, sodium tetrachloropalladate, palladium acetate or iridium sulfate.

[0010] The reaction interface of the polymer-supported noble metal catalyst is as high as 200-1100m 2 / g, and has good compatibility with biological enzyme catalysts.

[0011] The high molecular polymer supported noble metal catalyst is a metal single atom catalyst, and the metal on the high molecular polymer is distributed in a single atom.

[0012] The loading amount of the active component in the noble metal single-atom catalyst is < 1 wt%. To achieve single-atom distribution, first, the concentration of the noble metal compound solution needs to be controlled. If the concentration is too high, the conditions for forming single-atom distribution will be destroyed. Generally, the concentration of the noble metal compound solution is less than 15.4 mM. Second, the density VB of noble metal ions on the inner surface of the macromolecular polymer needs to satisfy the following relationship:

[0013] VB = (V × C) / (M × S)

[0014] where V represents the volume of the noble metal compound solution, in mL;

[0015] C represents the concentration of the noble metal compound solution, in mmol / mL;

[0016] M represents the amount of substance of the macromolecular polymer, in g;

[0017] S represents the specific surface area of the macromolecular polymer, in m 2 / g;

[0018] The value range of VB is from 0.0000077 to 0.000354 mmol / m2.

[0019] The preparation method of the noble metal single-atom catalyst of the present invention includes the following steps:

[0020] (1) Dissolve the noble metal compound in a solvent to prepare a noble metal compound solution;

[0021] (2) Add the macromolecular polymer treated with ethanol to the noble metal compound solution in step (1), shake in a gas bath constant temperature oscillator at room temperature for 4 h, filter to obtain a noble metal catalyst intermediate supported on the macromolecular polymer; soak the macromolecular polymer in absolute ethanol for 12 h, and then wash with deionized water to remove ethanol.

[0022] (3) Under ultrasonic conditions, add a reducing agent dropwise to the noble metal catalyst intermediate obtained in step (2), shake in a gas bath constant temperature oscillator at room temperature, and carry out a reduction reaction for 4 h. The reducing agent is selected from at least one of KBH4 or NaBH4;

[0023] (4) Wash the product obtained in step (3) 3 times with pure water, and soak for 1 - 2 h each time;

[0024] (5) Dry the product obtained in step (4) at room temperature for 10 h, and then dry in an oven at 50 °C for 4 h to obtain the macromolecular polymer-supported noble metal single-atom catalyst.

[0025] Spherical aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) were used for detection and analysis. The results showed that the metal on the prepared polymer-supported precious metal catalyst was distributed in a single atom.

[0026] The prepared high molecular polymer supported noble metal single atom catalyst can be used in environment and energy, as well as chemical-enzyme DKR.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] The present invention discloses a method for preparing a polymer-supported noble metal single-atom catalyst, using a polymer as a carrier to uniformly distribute metal atoms on the carrier surface to form a single-atom catalyst. The metal atom is selected from at least one of ruthenium, rhodium, palladium, iridium, platinum or cobalt. The polymer carrier is selected from at least one of non-polar, weakly polar, medium-polar or strongly polar polymers. The polarity of the carrier affects the microenvironment of the reaction. The polarity of the carrier used may affect the reaction. Different reactions may require different polar environments. Therefore, noble metal single-atom catalysts of different polarity series should be produced to meet the needs of various reactions.

[0029] The method for preparing a noble metal single-atom catalyst using a polymer as a carrier disclosed in the present invention is relatively simple, does not require complex equipment or high-temperature and high-pressure conditions, and has great potential for large-scale production. Due to the large specific surface area of the polymer carrier, the active component has a high dispersion, and a high atomic utilization rate is maintained, resulting in relatively high activity during the catalytic reaction. At the same time, the method of the present invention is applicable to the preparation of a variety of metal single-atom catalysts, effectively addressing the shortcomings of the prior art such as complex synthesis, difficulty in controlling the single-atom loading, and difficulty in large-scale catalyst preparation, thereby improving the universality of the single-atom catalyst synthesis method.

[0030] Taking sodium tetrachloropalladate as an example, the adsorption process is as follows: the concentration of sodium tetrachloropalladate solution is 7.23mM, the volume of the solution is 9ml, it is placed in a beaker, and 1.8g of high molecular polymer treated with ethanol is added, VB = 9×7.23 / 1000 / 1.8 / 450 = 0.0000798mmol / m 2 The polymer used is XAD-1180 polymer, which is adsorbed in an air bath constant temperature oscillator for 4 hours at room temperature, filtered, and dried at room temperature for 10 hours. After the polymer adsorbed with palladium ions is filtered, a KBH4 solution with a concentration of 55.62Mm is added dropwise thereto as a reducing agent. The reaction is carried out in an air bath constant temperature oscillator at room temperature for 4 hours, filtered, washed with pure water 3 times, each time for 1-2 hours, filtered, dried at room temperature for 12 hours, and then placed in an electric constant temperature blast drying oven at 50°C for 4 hours to obtain the noble metal single atom catalyst;

[0031] Detection Method: Titration is used to determine the concentration of the palladium ion solution before and after adsorption. This method can be used to determine the amount of palladium adsorbed by the polymer and, from there, to calculate the palladium loading on the polymer support. For other metals, the adsorption capacity can be determined using conventional detection methods.

[0032] The palladium loading was 1 wt% (palladium / support, dry basis). Aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) analysis revealed that the prepared metal catalyst exhibited a single-atom distribution. DETAILED DESCRIPTION

[0033] The following are examples of the present invention, which are intended only to illustrate the present invention and are not to be construed as limiting the present invention.

[0034] Example 1 Polar polymer-supported palladium single-atom catalyst

[0035] The high molecular polymer used is XAD-1180, and its indicators are as follows:

[0036]

[0037] The high molecular weight polymer was soaked in anhydrous ethanol for 12 hours, and then washed with deionized water to remove the ethanol and set aside.

[0038] The adsorption process is as follows: the concentration of sodium tetrachloropalladate solution is 7.23Mm, the volume of the solution is 9ml, it is placed in a small beaker, 1.8g of the high molecular polymer treated with ethanol is added, VB = 9×7.23 / 1000 / 1.8 / 450 = 0.0000798mmol / m 2 The polymer used was XAD-1180, which was adsorbed in a constant-temperature air bath oscillator for 4 hours at room temperature. The adsorbed palladium ions were filtered, and a 55.62 mM KBH4 solution was added dropwise as a reducing agent, with the amount being 5-15 equivalents of the metal ions. The reaction was continued in a constant-temperature air bath oscillator for 4 hours at room temperature, filtered, and washed with purified water three times for 1-2 hours each time. The reaction was then dried at room temperature for 12 hours, and then dried in an electric constant-temperature forced air drying oven at 50°C for 4 hours to obtain 0.677 g of the noble metal single-atom catalyst.

[0039] The palladium loading was 1 wt% (palladium / support, dry basis). Aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) analysis revealed that the prepared metal catalyst exhibited a single-atom distribution.

[0040] Example 2 Non-polar Polymer-Supported Palladium Single-Atom Catalyst

[0041] The polymer used is XDA-1, and its various indicators are as follows:

[0042]

[0043] The adsorption process is as follows: The concentration of sodium tetrachloropalladate solution is 3.65 mM, the solution volume is 9 ml, placed in a small beaker, and 1.8 g of the polymer treated with ethanol is added. VB = 9×3.65 / 1000 / 1.8 / 1050 = 0.0000173 mmol / m 2 The polymer used is XDA-1 type polymer. It is shaken and adsorbed in a gas bath constant temperature oscillator at room temperature for 4 hours, filtered, and after the polymer adsorbed with palladium ions is filtered dry, a KBH4 solution with a concentration of 55.62 Mm is added dropwise as a reducing agent, and its dosage is 5-15 equivalents of metal ions. It reacts in a gas bath constant temperature oscillator at room temperature for 4 h, filtered, washed with pure water 3 times, 1-2 h each time, filtered dry, dried at room temperature for 12 h, and then placed in an electrothermal constant temperature forced air drying oven and baked at 50 °C for 4 h to obtain 0.681 g of the precious metal single-atom catalyst.

[0044] Detection shows that the palladium loading is 0.5 wt% (palladium / support, dry basis). Detection and analysis by aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) show that the prepared metal catalyst is in a single-atom distribution.

[0045] Example 3 Weakly Polar Polymer-Supported Palladium Single-Atom Catalyst

[0046] The polymer used is NKA-II, and its various indicators are as follows:

[0047]

[0048]

[0049] The adsorption process is as follows: The concentration of sodium tetrachloropalladate solution is 1.8 mM, the solution volume is 9 ml, placed in a small beaker, and 1.8 g of the polymer treated with ethanol is added, VB = 9×1.8 / 1000 / 1.8 / 275 = 0.0000326 mmol / m 2The polymer used is NKA-II type polymer. It is shaken and adsorbed in a constant temperature air bath oscillator at room temperature for 4 hours, then filtered. After the polymer adsorbed with palladium ions is dried by filtration, a KBH4 solution with a concentration of 55.62 Mm is added dropwise as a reducing agent, and its dosage is 5-15 equivalents of metal ions. The reduction reaction is carried out in a constant temperature air bath oscillator at normal temperature for 4 h, then filtered, washed 3 times with pure water, 1-2 h each time, dried by filtration, dried at room temperature for 12 h, and then placed in an electrothermal constant temperature forced air drying oven and baked at 50 °C for 5 h to obtain 0.673 g of the noble metal single-atom catalyst.

[0050] Detection shows that the palladium loading is 0.258 wt% (palladium / support, dry basis). The spherical aberration corrected scanning transmission electron microscope (AC-STEM) and extended X-ray absorption fine structure spectrum (EXAFS) are used for detection and analysis, and the results show that the prepared metal catalyst is in the form of single atoms.

[0051] The polar polymer-supported palladium single-atom catalyst in Example 4

[0052] The polymer used is HPD-722, and its various indexes are as follows:

[0053]

[0054]

[0055] The adsorption process is as follows: the concentration of sodium tetrachloropalladate solution is 0.9 mM, the solution volume is 9 ml, placed in a small beaker, 1.8 g of the polymer treated with ethanol is added, VB = 9×0.9 / 1000 / 1.8 / 425 = 0.0000109 mmol / m 2 The polymer used is HPD-722 type polymer. It is shaken and adsorbed in a constant temperature air bath oscillator at room temperature for 4 hours, then filtered. After the polymer adsorbed with palladium ions is dried by filtration, a KBH4 solution with a concentration of 55.62 Mm is added dropwise as a reducing agent, and its dosage is 5-15 equivalents of metal ions. The reaction is carried out in a constant temperature air bath oscillator at normal temperature for 4 h, then filtered, washed 3 times with pure water, 1-2 h each time, dried by filtration, dried at room temperature for 12 h, and then placed in an electrothermal constant temperature forced air drying oven and baked at 50 °C for 4 h to obtain 0.680 g of the noble metal single-atom catalyst.

[0056] Detection shows that the palladium loading is 0.129 wt% (palladium / support, dry basis). The spherical aberration corrected scanning transmission electron microscope (AC-STEM) and extended X-ray absorption fine structure spectrum (EXAFS) are used for detection and analysis, and the results show that the prepared metal catalyst is in a single-atom distribution.

[0057] Example 5 Non-polar Polymer-Supported Iridium Single-Atom Catalyst

[0058] The polymer used is LSA-20, and its various indicators are as follows:

[0059]

[0060]

[0061] The adsorption process is as follows: The concentration of iridium sulfate solution is 0.723 mM, the solution volume is 9 ml, placed in a small beaker, 1.8 g of the polymer treated with ethanol is added, VB = 0.723×8.28 / 1000 / 1.8 / 460 = 0.00000786 mmol / m 2 The polymer used is LSA-20 type polymer. It is shaken and adsorbed in a gas bath constant temperature oscillator at room temperature for 4 hours, filtered, and after the polymer adsorbed with iridium ions is dried, a KBH4 solution with a concentration of 55.62 Mm is added dropwise as a reducing agent, and its dosage is 5-15 equivalents of metal ions. The reduction reaction is carried out in a gas bath constant temperature oscillator at room temperature for 4 h, filtered, washed with pure water 3 times, 1-2 h each time, dried, dried at room temperature for 12 h, and then placed in an electrothermal constant temperature forced air drying oven at 50 °C for 5 h to obtain 0.673 g of the precious metal single-atom catalyst.

[0062] Detection shows that the iridium loading is 0.10 wt% (palladium / support, dry basis). Detection and analysis by aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) show that the prepared metal catalyst is in a single-atom distribution.

[0063] Example 6 Non-polar Polymer-Supported Cobalt Single-Atom Catalyst

[0064] The polymer used is XAD-2, and its various indicators are as follows:

[0065]

[0066] The adsorption process is as follows: The cobalt sulfate solution used for adsorption has a concentration of 0.25 - 1.25 mM (mmol / L), the solution volume is 500 - 1000 mL, placed in a container with stirring, 100 - 400 g of the polymer treated with ethanol is added, VB = 0.0000027 - 0.000354 mmol / m 2, Stir at room temperature for 1 hour, filter, and after filtering and drying the polymer adsorbed with cobalt ions, slowly add dropwise a KBH4 solution with a concentration of 55.62 Mm as a reducing agent. Conduct a reduction reaction in a gas bath constant temperature oscillator under normal temperature conditions for 4 h, then filter, wash with pure water 3 times, 1 - 2 h each time, filter and dry, dry at room temperature for 12 h, and then dry in an oven at 50 °C for 5 hours to obtain 37.45 - 151.05 g of cobalt single-atom catalyst.

[0067] The detection shows that the cobalt loading is 0.1 - 0.95 wt% (cobalt / support, dry basis). Using aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) for detection and analysis, the results show that the prepared metal catalyst has a single-atom distribution.

[0068] Example 7 Polar Polymer-Supported Ruthenium Single-Atom Catalyst

[0069] The polymer used is DM-130. The adsorption process is as follows: The ruthenium sulfate solution used for adsorption has a concentration of 0.15 - 0.75 mM (mmol / L), the solution volume is 500 - 1000 mL, VB = 0.0000027 - 0.000354 mmol / m 2 , Place it in a container with stirring, add 100 - 400 g of the polymer treated with ethanol, stir at room temperature for 1 hour, filter, and after filtering and drying the polymer adsorbed with ruthenium ions, slowly add dropwise a KBH4 solution with a concentration of 55.62 Mm as a reducing agent, and its dosage is 5 - 15 equivalents of metal ions. Conduct a reduction reaction in a gas bath constant temperature oscillator under normal temperature conditions for 4 h, then filter, wash with pure water 3 times, 1 - 2 h each time, filter and dry, dry at room temperature for 12 h, and then dry in an oven at 50 °C for 5 hours to obtain 37.12 - 151.75 g of immobilized ruthenium sulfate catalyst.

[0070] The detection shows that the ruthenium loading is 0.08 - 0.93 wt% (ruthenium / support, dry basis). Using aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) for detection and analysis, the results show that the prepared metal catalyst has a single-atom distribution.

[0071] Example 8 Weakly Polar Polymer-Supported Ruthenium Single-Atom Catalyst

[0072] The polymer used is HP2MG. The adsorption process is as follows: The ruthenium sulfate solution used for adsorption has a concentration of 0.15 - 0.75 M (mol / L), the solution volume is 500 - 1000 mL, VB = 0.0000027 - 0.000354 mmol / m 2, place it in a stirred container, add 100-400g of ethanol-treated polymer, stir at room temperature for 1 hour, filter, filter the polymer after adsorbing ruthenium ions, and add KBH4 solution with a concentration of 55.62Mm dropwise as a reducing agent. Perform the reduction reaction in a gas bath constant temperature oscillator at room temperature for 4h, then filter, wash with pure water 3 times, each time for 1-2h, filter, dry, dry at room temperature for 12h, and then dry in a 50℃ oven for 5 hours to obtain 36.87-131.88g of ruthenium single atom catalyst.

[0073] The ruthenium loading was 0.11-0.82 wt% (ruthenium / support, dry basis). Aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) analysis revealed that the prepared metal catalyst exhibited a monoatomic distribution.

[0074] Example 9 Non-polar polymer-supported rhodium single atom catalyst

[0075] The high molecular polymer used is H103, and the adsorption process is as follows: the concentration of rhodium sulfate solution used for adsorption is 0.25-1.0mM (mmol / L), the solution volume is 500-1000mL, VB=0.0000027-0.000354mmol / m 2 Place the mixture in a stirred container and add 100-400g of an ethanol-treated polymer (X-5 type). Stir at room temperature for 1 hour, filter, and drain the adsorbed rhodium ion polymer. Then, dropwise add a 55.62 mM KBH4 solution as a reducing agent (5-15 equivalents of the metal ion) to the mixture. Reduction is carried out in a constant-temperature oscillator in an air bath at room temperature for 4 hours. The mixture is then filtered and washed with purified water three times for 1-2 hours each time. Drain and dry at room temperature for 12 hours, then dry in a 50°C oven for 5 hours to yield 38.35-151.88g of a single-atom rhodium catalyst.

[0076] The rhodium loading was found to be 0.11-0.92 wt% (rhodium / support, dry basis). Aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) analysis revealed that the metal catalyst exhibited a monoatomic distribution.

[0077] Polar polymer-supported rhodium single atom catalyst in Example 10

[0078] The high molecular polymer used is DA201-C, and the adsorption process is as follows: the concentration of rhodium sulfate solution used for adsorption is 0.25-1.0mM, the solution volume is 500-1000mL, VB=0.0000027-0.000354mmol / m 2 Place the mixture in a stirred container and add 100-400g of the ethanol-treated polymer. Stir at room temperature for 1 hour, filter, and drain the polymer after adsorbing rhodium ions. Then, dropwise add a 55.62 mM KBH4 solution as a reducing agent, using 5-15 equivalents of the metal ion. Reduction is carried out in a constant-temperature oscillator in an air bath at room temperature for 4 hours. The mixture is then filtered and washed with purified water three times, each for 1-2 hours. Drain and dry at room temperature for 12 hours, then dry in a 50°C oven for 5 hours to yield 39.41-131.88g of the rhodium single-atom catalyst.

[0079] The rhodium loading was found to be 0.21-0.72 wt% (rhodium / support, dry basis). Aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) analysis revealed that the metal catalyst exhibited a monoatomic distribution.

[0080] Example 11 Weakly polar polymer-supported rhodium single atom catalyst

[0081] The high molecular polymer used is XDA-18, and the adsorption process is as follows: the concentration of the adsorption rhodium sulfate solution used is 0.25-1.0M (mol / L), the solution volume is 500-1000mL, VB=0.0000027-0.000354mmol / m 2 Place the mixture in a stirred container and add 100-400g of the ethanol-treated polymer. Stir at room temperature for 1 hour, filter, and drain the polymer after adsorbing rhodium ions. Then, dropwise add a 55.62 mM KBH4 solution as a reducing agent, using 5-15 equivalents of the metal ion. Reduction is carried out in a constant-temperature oscillator in an air bath at room temperature for 4 hours. The mixture is then filtered and washed with purified water three times, each for 1-2 hours. Drain and dry at room temperature for 12 hours, then dry in a 50°C oven for 5 hours to yield 38.37-152.18g of the rhodium single-atom catalyst.

[0082] The rhodium loading was found to be 0.13-0.95 wt% (rhodium / support, dry basis). Aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS) analysis revealed that the metal catalyst exhibited a monoatomic distribution.

[0083] Example 12 Preparation of (R)-N-(1-phenylethyl)acetamide by DKR reaction

[0084] Using the palladium single-atom catalyst prepared in Example 2 as the in-situ racemization catalyst and the immobilized lipase IM-100 from Qingdao Blue Ocean Biotechnology Co., Ltd. as the resolution reaction catalyst, the DKR reaction was carried out. Using racemic α-phenylethylamine as the substrate and ethyl methoxyacetate as the acyl donor, the reaction conditions were as follows: the reaction volume was 4 ml, the concentration of α-phenylethylamine was 0.05 mol / mL, the concentration of ethyl methoxyacetate was 0.0625 mmol / mL, 0.02 g of immobilized lipase IM-100 was added, and 160 mg of the palladium single-atom racemization catalyst prepared in Example 2, with a palladium content of 0.8 mg, was added. The reaction temperature was 60 °C and the reaction time was 10 hours to prepare (R)-2-methoxy-N-(1-phenylethyl)acetamide. The enantiomeric excess ee and the conversion rate were determined by high-performance liquid chromatography. The liquid chromatography column was a chiral chromatography column. The mobile phase was n-hexane: isopropanol: diethylamine (90:10:0.1), the detection wavelength was 254 nm, the column oven temperature was 35 °C, the flow rate was 1 mL / min, and the injection volume was 20 μL. The experimental results were as follows: the substrate conversion rate was 100%, the product yield was 100%, and the product ee was 100%, indicating that the prepared single-atom catalyst had high efficiency and good biocompatibility with the enzyme. The immobilized lipase IM-100 used had absolute selectivity for the substrate phenylethylamine and the donor ethyl methoxyacetate.

[0085] Comparative Example 1 Non-polar polymer-supported palladium single-atom catalyst

[0086] The polymer used was XDA-1. The adsorption process was as follows: the concentration of sodium tetrachloropalladate solution was 200 mM, the solution volume was 18 ml, placed in a small beaker, and 1.8 g of the polymer treated with ethanol was added. VB = 18×200 / 1000 / 1.8 / 1050 = 0.00196 mmol / m 2 , and it was shaken and adsorbed in a gas bath constant temperature oscillator at room temperature for 4 hours, filtered, and the polymer adsorbed with palladium ions was dried and then slowly added dropwise with a KBH4 solution with a concentration of 55.62 Mm as the reducing agent. The reaction was carried out in a gas bath constant temperature oscillator at room temperature for 4 h, washed 3 times with pure water, 1 - 2 h each time, dried, dried at room temperature for 12 h, and then placed in an electrothermal constant temperature forced air drying oven at 50 °C for 5 h.

[0087] The detection showed that the palladium loading was 4.53 wt% (palladium / support, dry basis). Detection and analysis were carried out using aberration-corrected scanning transmission electron microscopy (AC-STEM) and extended X-ray absorption fine structure spectroscopy (EXAFS). The results showed that the prepared metal catalyst was distributed in atomic clusters or nanoparticles.

[0088] Comparative Example 2 Preparation of (R)-N-(1-phenylethyl)acetamide by DKR reaction

[0089] A DKR reaction was performed using the palladium single-atom catalyst prepared in Comparative Example 1 as an in-situ racemization catalyst and immobilized lipase IM-100 from Qingdao Weilan Biotechnology Co., Ltd. as a resolution catalyst. Racemic α-phenylethylamine was used as the substrate, and ethyl methoxyacetate was used as the acyl donor. The reaction conditions were: a 4 ml reaction volume, an α-phenylethylamine concentration of 0.05 mol / mL, and an ethyl methoxyacetate concentration of 0.0625 mmol / mL. 0.02 g of immobilized lipase IM-100 was added, along with 17.66 mg of the immobilized palladium single-atom racemization catalyst prepared in Comparative Example 2 (0.8 mg based on palladium content). The reaction temperature was 60°C, and the reaction time was 10 hours to prepare (R)-2-methoxy-N-(1-phenylethyl)acetamide. The enantiomeric excess (ee) and conversion were determined by high-performance liquid chromatography (HPLC) using a chiral column. The mobile phase consisted of n-hexane:isopropanol:diethylamine (90:10:0.1), with detection at 254 nm, a column oven temperature of 35°C, a flow rate of 1 mL / min, and an injection volume of 20 μL. The experimental results showed a substrate conversion of 59%, a product yield of 59%, and a product ee of 100%. The immobilized lipase IM-100 exhibited absolute selectivity for the substrate phenylethylamine and the donor ethyl methoxyacetate.

[0090] Comparing Example 12 with Comparative Example 2, it can be seen that the yield ratio between the two is 100:59, a huge difference, which is sufficient to show that the efficiency of the single-atom catalyst prepared by this technical solution is much higher than that of conventional catalysts with non-single-atom distribution.

Claims

1. A polymer-supported noble metal single-atom catalyst, characterized in that Comprising: (1) A carrier material selected from non-polar high molecular polymers, weakly polar high molecular polymers, medium polar high molecular polymers or polar high molecular polymers; And (2) an active ingredient which is a noble metal with a single-atom distribution, and the noble metal is selected from at least one of cobalt, ruthenium, rhodium or palladium. The active ingredient is loaded on the surface of the carrier material through a noble metal compound solution, and the noble metal compound solution is selected from at least one of cobalt sulfate, ruthenium sulfate, rhodium sulfate, palladium sulfate, sodium tetrachloropalladate or palladium acetate.

2. The catalyst according to claim 1, characterized in that: The loading amount of the active ingredient ≤ 1 wt%; the concentration of the noble metal compound solution is less than 15.4 mM; the noble metal ion density VB of the noble metal compound solution satisfies the following relationship: VB = (V × C) / (M × S) Wherein, V represents the volume of the noble metal compound solution, with the unit of mL; C represents the concentration of the noble metal compound solution, with the unit of mmol / mL; M represents the amount of substance of the high molecular polymer, with the unit of g; S represents the specific surface area of the polymer, in m 2 / g; The value range of VB is from 0.0000077 to 0.000354 mmol / m 2 .

3. The catalyst according to claim 1, characterized in that, Its preparation method includes the following steps: (1) Dissolve the noble metal compound in a solvent to prepare a noble metal compound solution; (2) Add the ethanol-treated high molecular polymer to the noble metal compound solution obtained in step (1), shake it in an oscillator at room temperature, and filter to obtain a noble metal catalyst intermediate; (3) Dropwise add a reducing agent to the noble metal catalyst intermediate obtained in step (2), shake it in an oscillator at room temperature to carry out a reduction reaction; the reducing agent is selected from at least one of KBH4 or NaBH4; (4) Wash the product obtained in step (3) with pure water, and soak it for 1 - 2 h each time; (5) Preliminarily dry the product obtained in step (4) at room temperature, and then dry it in an oven to obtain the noble metal single-atom catalyst with the high molecular polymer as the carrier.

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