Use of carbon nanotube confined clusters in heterogeneous catalytic reactions

Abstract

The application discloses an application of carbon nanotube confined clusters in heterogeneous catalytic reactions and belongs to the technical field of catalysis. The application provides the application of carbon nanotube confined clusters in heterogeneous catalytic reactions, wherein the carbon nanotube confined clusters comprise carbon nanotubes and clusters confined in the carbon nanotubes, and the clusters are selected from at least one of heteropolyacids, heteropolyacid salts, metal clusters and metal organic frameworks. In the application, the catalytic reaction efficiency and selectivity of organic matter oxidation / reduction can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of catalysis technology, and in particular to the application of carbon nanotube confined clusters in heterogeneous catalytic reactions. Background Technology

[0002] Carbon nanotubes (CNTs) were first discovered using high-resolution transmission electron microscopy in the products of carbon fiber production via the arc electrochemical process. They are tubular carbon molecules where each carbon atom is sp2 hybridized and bonded together by carbon-carbon σ bonds, forming a hexagonal honeycomb structure that serves as the nanotube's framework. The pair of unhybridized p electrons on each carbon atom form a conjugated π electron cloud spanning the entire nanotube. The diameter of single-walled carbon nanotubes ranges from approximately 0.5 to 3 nm. Due to the integrity of the single-walled carbon nanotube wall, they exhibit high chemical inertness and are generally difficult to use directly as active sites for catalytic applications.

[0003] Researchers have conducted considerable work on the catalytic performance of single-walled carbon nanotubes, including but not limited to loaded metal nanoparticles, covalently grafted groups, and mechanically interlocked cyclic molecules. However, the materials obtained by these methods still have certain limitations in the field of catalysis, such as the inability to achieve industrial-scale preparation, high requirements for equipment, and the need for complex chemical synthesis processes. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes the application of carbon nanotube confined clusters in heterogeneous catalytic reactions, which can effectively improve the catalytic efficiency of organic oxidation / reduction reactions.

[0005] According to an embodiment of a first aspect of the present invention, an application of carbon nanotube confined clusters in heterogeneous catalytic reactions is provided, wherein the carbon nanotube confined clusters include carbon nanotubes and clusters confined within the carbon nanotubes, the clusters being selected from at least one of heteropolyacids, heteropolyacid salts, metal clusters, and metal-organic frameworks.

[0006] The application of the present invention, according to embodiments thereof, has at least the following beneficial effects:

[0007] In the carbon nanotube confined clusters used in this invention, the cluster molecules regulate the electronic structure of the carbon nanotubes, thereby realizing the catalytic oxidation of thioethers and the reduction of p-nitrophenol based on electronic structure regulation, and significantly accelerating the above organic reactions.

[0008] In traditional technologies, carbon nanotube confined clusters are mainly used in electronic devices, such as in the fabrication of transistors; transistor fabrication requires materials to possess electrical conductivity. Furthermore, this strategy of carbon nanotube confined clusters allows for the manipulation of the electronic structure of carbon nanotubes by the clusters, thereby separating single-walled carbon nanotubes with uniform properties or high diameter. On the other hand, carbon nanotubes can protect clusters from degradation during charge and discharge, and this has also been applied in the anode materials of sodium-ion batteries. This invention discovers that carbon nanotube confined clusters possess catalytic activity and creatively applies them to the field of heterogeneous catalysis of organic compounds. The properties utilized as catalysts differ from those used in traditional technologies. Moreover, after applying carbon nanotube confined clusters to catalysis, this invention achieved nearly 100% conversion rates in the catalytic oxidation of sulfides and the catalytic reduction of p-nitrophenol (including stationary and flow reactions), demonstrating remarkable catalytic activity and selectivity.

[0009] The heterogeneous catalytic reaction refers to a two-phase reaction consisting of solid carbon nanotube confined clusters and a substrate dissolved in a liquid phase.

[0010] According to some embodiments of the present invention, the cluster comprises at least one of the following elements: hydrogen (H), nitrogen (N), phosphorus (P), sulfur (S), oxygen (O), carbon (C), boron (B), molybdenum (Mo), tungsten (W), platinum (Pt), rhodium (Rh), ruthenium (Ru), gold (Au), silver (Ag), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), chromium (Cr), and vanadium (V). Specifically, it comprises at least one metallic element and one non-metallic element, wherein the non-metallic element has the function of stabilizing the metallic element.

[0011] According to some embodiments of the present invention, when the cluster includes the heteropolyacid, the heteropolyacid is H3PMo. 12 O 40 .

[0012] According to some embodiments of the present invention, when the cluster includes the metal cluster, the metal cluster includes (NH4)9Ag9(mba)9.

[0013] According to some embodiments of the present invention, the clusters possess redox properties or acid-base properties. This allows for better reaction with the carbon nanotubes, promoting the formation of the carbon nanotube-confined clusters.

[0014] According to some embodiments of the present invention, the particle size of the clusters is 0.3–2 nm. This provides a high degree of matching with the inner diameter of the carbon nanotubes, which is beneficial for the clusters to fill the inner cavity of the carbon nanotubes.

[0015] According to some embodiments of the present invention, the carbon nanotube confined clusters are prepared by a method comprising the following steps:

[0016] S1. The clusters and carbon nanotubes are mixed and assembled in a solvent;

[0017] S2. The mixture obtained from solid-liquid separation step S1 is washed and dried.

[0018] This invention utilizes the redox properties and size effect of different clusters to modulate the electronic structure of carbon nanotubes. Through electron transfer, it effectively regulates the electronic structure and interfacial properties of carbon nanotubes, thereby achieving delocalized electron catalysis and ultimately enabling the selective oxidation of thioethers and the reduction of p-nitrophenol. The method provided in this invention is simple to operate, has high reproducibility in product preparation, and is suitable for the preparation of gram-scale or even higher gravimetric catalysts.

[0019] According to some embodiments of the present invention, step S1 specifically involves dispersing the clusters in the solvent to obtain a cluster dispersion; then mixing the cluster dispersion and the carbon nanotubes for mixing and assembly.

[0020] According to some embodiments of the present invention, in step S1, the solvent includes at least one selected from water, ethanol, toluene, xylene, chloroform, and tetrahydrofuran. The solvent is capable of dissolving the clusters.

[0021] According to some embodiments of the present invention, in step S1, the carbon nanotubes include single-walled carbon nanotubes.

[0022] According to some embodiments of the present invention, in step S1, the mass ratio of the clusters to carbon nanotubes is (0.1–50):1. Specifically, it can be 18–22:1. More specifically, it can be about 20:1 or 1–1.5:1.

[0023] According to some embodiments of the present invention, the concentration of the clusters in the cluster dispersion is 1–200 mg / mL. For example, it can be 60–70 mg / mL.

[0024] According to some embodiments of the present invention, in step S1, the temperature of the mixing and assembly is 0–100°C. This allows for control of the assembly rate and ratio between the clusters and the carbon nanotubes. Specifically, the temperature of the mixing and assembly can be 20–40°C, for example, approximately 25°C.

[0025] According to some embodiments of the present invention, in step S1, the mixing and assembly time is 10 min to 15 h. For example, it can be 20 to 50 h. More specifically, it can be about 48 h.

[0026] According to some embodiments of the present invention, in step S1, the mixing and assembly is carried out under stirring conditions. The stirring speed is 100 to 2000 rpm. For example, it can be 800 to 1000 rpm.

[0027] According to some embodiments of the present invention, in step S2, the solid-liquid separation method includes at least one of centrifugation and filtration.

[0028] According to some embodiments of the present invention, the washing and drying methods in step S2 are not strictly limited and can be adjusted according to the actual reaction conditions available in actual production. For example, washing can be water washing; drying can be forced air drying; the temperature of forced air drying is 60-100°C, more specifically about 80°C.

[0029] According to some embodiments of the present invention, the heterogeneous catalytic reaction includes the catalytic oxidation of sulfides or the catalytic reduction of nitrophenol.

[0030] According to some embodiments of the present invention, the heterogeneous catalytic reaction is at least one of a stationary reaction and a flow reaction.

[0031] According to some embodiments of the present invention, when the heterogeneous catalytic reaction includes the immobilization reaction, the immobilization reaction includes mixing and reacting the carbon nanotube confined clusters, the substrate, and the reaction promoter, followed by separation.

[0032] According to some embodiments of the present invention, the fixation reaction includes the following steps:

[0033] A1. The carbon nanotube confined clusters, the substrate solution, and the reaction aid are mixed and reacted.

[0034] A2. Solid-liquid separation to remove solids.

[0035] According to some embodiments of the present invention, in step A1, the order of adding materials is to mix the carbon nanotube confined clusters and the substrate solution, and then react with the reaction aid.

[0036] According to some embodiments of the present invention, in step A1, the solvent used in the substrate solution includes at least one of ethanol, water and tetrahydrofuran.

[0037] According to some embodiments of the present invention, in step A1, the substrate includes at least one of thioether and p-nitrophenol.

[0038] The sulfides include diphenyl sulfide (CAS: 139-66-2), anisole (CAS: 100-68-5), dibutyl sulfide (CAS: 544-40-1), dipropyl sulfide (CAS: 111-47-7), and tetrahydrothiophene (CAS: 110-01-0).

[0039] According to some embodiments of the present invention, in step A1, the concentration of the substrate in the solution is 0.1–10 mmol / L. Specifically, it can be about 0.1–0.5 mmol / L, or 5–10 mmol / L.

[0040] According to some embodiments of the present invention, in step A1, the ratio of the carbon nanotube confined clusters to the substrate solution is 0.2–2.5 mg / mL. Specifically, it can be 0.5–1 mg / mL.

[0041] According to some embodiments of the present invention, in step A1, the reaction aid includes at least one of an oxidizing agent and a reducing agent.

[0042] According to some embodiments of the present invention, the oxidant includes at least one of oxygen, hydrogen peroxide, and tert-butyl hydrogen peroxide.

[0043] According to some embodiments of the present invention, the reducing agent includes at least one of hydrogen and sodium borohydride.

[0044] According to some embodiments of the present invention, when the reaction aid is an oxidant, and the oxidant is hydrogen peroxide, the volume ratio of the oxidant to the substrate solution is 1 to 1.5:100. Specifically, it can be about 1.2:100. The concentration of the hydrogen peroxide is 25 to 35 wt%. Specifically, it can be about 30 wt%.

[0045] According to some embodiments of the present invention, when the reaction aid is a reducing agent, the ratio of the reducing agent to the substrate solution is 0.7 to 1.5 mg / mL. For example, it can specifically be 0.8 mg / mL.

[0046] According to some embodiments of the present invention, in step A1, the duration of the mixing reaction is 1 to 100 minutes. For example, it can be 60 to 70 minutes, or 5 to 6 minutes.

[0047] According to some embodiments of the present invention, in step A1, the mixing reaction is carried out under stirring. The stirring speed is 1000 to 2000 rpm. For example, it can be about 1500 rpm.

[0048] According to some embodiments of the present invention, in step A2, the function of solid-liquid separation is to remove the confined carbon nanotube clusters. Specific methods include at least one of filtration and centrifugation.

[0049] According to some embodiments of the present invention, when the heterogeneous catalytic reaction includes the flow reaction, the flow reaction includes creating relative motion between the catalyst and the phase to be catalyzed;

[0050] The catalyst includes a support and the carbon nanotube confinement clusters supported on the support;

[0051] The phase to be catalyzed includes a substrate and a reaction promoter.

[0052] According to some embodiments of the present invention, the flow reaction step is as follows:

[0053] B1. The support and the carbon nanotube confined clusters are wet-mixed and dried to obtain the catalyst;

[0054] B2. Fix the catalyst and pass the phase to be catalyzed through the catalyst;

[0055] The phase to be catalyzed includes a substrate and a reaction promoter.

[0056] According to some embodiments of the present invention, in step B1, the mass ratio of the support to the carbon nanotube confinement clusters is 50:1 to 5; specifically, it can be about 50:2. In actual production, this ratio is not strictly limited and can be adjusted according to the performance of the support. For example, when the support is activated carbon, the above ratio is between 50:1 and 2.

[0057] According to some embodiments of the present invention, in step B1, the carrier includes at least one of metal oxide, silica gel, quartz sand, activated carbon, molecular sieve and sponge.

[0058] According to some embodiments of the present invention, in step B1, the mesh size of the carrier is 40 to 60 mesh.

[0059] The metal oxide includes at least one of aluminum oxide, zirconium oxide, and titanium oxide.

[0060] According to some embodiments of the present invention, in step B1, the dispersant used in the wet mixing includes water.

[0061] According to some embodiments of the present invention, in step B1, the drying method includes rotary evaporation. Thus, the carbon nanotube clusters can be loaded onto the support.

[0062] According to some embodiments of the present invention, in step B2, the fixing refers to fixing the catalyst onto a reaction vessel. The reaction vessel includes at least one of a self-filtering membrane and a quartz tube. For example, it can be fixed inside a quartz tube. This establishes a platform for a flow reaction.

[0063] According to some embodiments of the present invention, in step B2, the substrate includes at least one of thioether and p-nitrophenol.

[0064] The sulfides include diphenyl sulfide (CAS: 139-66-2), anisole (CAS: 100-68-5), dibutyl sulfide (CAS: 544-40-1), dipropyl sulfide (CAS: 111-47-7), and tetrahydrothiophene (CAS: 110-01-0).

[0065] According to some embodiments of the present invention, in step B2, the reaction aid includes at least one of an oxidizing agent and a reducing agent.

[0066] According to some embodiments of the present invention, the oxidant includes at least one of oxygen, hydrogen peroxide, and tert-butyl hydrogen peroxide.

[0067] According to some embodiments of the present invention, the reducing agent includes at least one of hydrogen and sodium borohydride.

[0068] According to some embodiments of the present invention, in step B2, when the reaction promoter is an oxidant and the oxidant is hydrogen peroxide, the volume ratio of the oxidant to the substrate solution in the catalytic phase is 1 to 1.5:100. Specifically, it can be approximately 1.2:100.

[0069] According to some embodiments of the present invention, in step B2, when the reaction promoter is a reducing agent in the phase to be catalyzed, the molar ratio of the reducing agent to the substrate is 10 to 30:1. For example, it can be 15 to 20:1.

[0070] According to some embodiments of the present invention, in step B2, the passing speed is 100-200 mm / min. For example, it can be approximately 170-180 mm / min.

[0071] According to some embodiments of the present invention, in step B2, the process includes injecting the phase to be catalyzed by a flow pump, and the catalyst flowing through the quartz tube to complete the heterogeneous catalytic reaction.

[0072] Unless otherwise specified, the term "about" in this invention actually means that the error is allowed to be within ±2%, for example, about 100 is actually 100 ± 2% × 100.

[0073] Unless otherwise specified, "between" in this invention includes the number itself, for example, "between 2 and 3" includes the endpoint values ​​2 and 3.

[0074] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0075] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0076] Figure 1 This is a high-angle annular dark-field electron microscope image of the carbon nanotube confined clusters obtained in Example 1 of the material preparation of the present invention;

[0077] Figure 2 This is a high-angle annular dark-field electron microscope image of the carbon nanotube confined clusters obtained in Example 2 of the material preparation of the present invention;

[0078] Figure 3 These are the catalytic oxidation results of sulfide in Example 1 and Comparative Examples 1-2 of the present invention;

[0079] Figure 4 The graphs show the catalytic reduction results of p-nitrophenol in Example 2 and Comparative Examples 1-2 of this invention.

[0080] Figure 5 This is a diagram showing the catalytic reduction results of p-nitrophenol in Example 3 of the present invention. Detailed Implementation

[0081] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0082] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0083] Material Preparation Example 1

[0084] This example demonstrates the preparation of a carbon nanotube confined cluster. The specific steps are as follows:

[0085] S1. Based on carbon nanotubes: H3PMo 12 = 1:20 mass ratio, 200mg H3PMo at room temperature (approximately 25℃) 12The powder was dissolved in 3 mL of deionized water to obtain a cluster dispersion. Then, 10 mg of carbon nanotubes were dispersed in the above cluster dispersion, and the mixture was stirred for 48 hours using a constant-temperature magnetic stirrer (800 rpm). The carbon nanotubes used in this example were Tuball tubes from OCSiAl, with a diameter of 0.9-2.2 nm. The H3PMo used... 12 Its diameter is approximately 1 nm.

[0086] S2. After solid-liquid separation by centrifugation, the resulting solid was repeatedly washed with deionized water by centrifugation (the solid-liquid separation during this process was performed by centrifugation). Then, it was dried in a drying oven at 80°C to obtain confined carbon nanotube clusters, wherein the clusters were heteropolyacid salts (abbreviated as {PMo... 12}@carbon nanotubes).

[0087] For the {PMo obtained in this example 12 The carbon nanotube sample was characterized by transmission electron microscopy (TEM). The specific procedure was as follows: a small amount of powder sample was placed in an ethanol solution and sonicated for 5 minutes in an ultrasonic disperser to disperse the sample into a suspension. 20 μL of the dispersion was dropped onto a copper mesh microgrid. After adsorption for 3 minutes, the copper mesh was removed with tweezers, and any remaining sample solution was blotted dry with filter paper. The sample on the copper mesh was observed using TEM. The TEM results showed that {PMo... 12} was filled into carbon nanotubes, and the assembled {PMo 12 The carbon nanotube sample packing was uniform. It can be expected that the carbon nanotube confined clusters obtained in this example will catalyze the oxidation of sulfides. The high-angle annular dark-field electron microscopy image of the product obtained in this example is shown below. Figure 1 As shown.

[0088] Material Preparation Example 2

[0089] This example demonstrates the preparation of a carbon nanotube confined cluster. The specific steps are as follows:

[0090] S1. Weigh an appropriate amount of raw material according to the mass ratio of carbon nanotubes to (NH4)9Ag9(mba)9 of 1:1.2. Disperse 10 mg of carbon nanotubes in 800 μL of 15 mg / mL (NH4)9Ag9(mba)9 cluster aqueous solution at room temperature, and stir with a constant temperature magnetic stirrer at about 25 °C for 48 h.

[0091] S2. After solid-liquid separation by centrifugation, deionized water is repeatedly added to the obtained solid for centrifugal washing (the solid-liquid separation during this period is carried out by centrifugation). Then, the solid is dried in a drying oven at 80°C to obtain carbon nanotube confined clusters, wherein the clusters are metal clusters (abbreviated as {Ag9}@carbon nanotubes).

[0092] The {Ag9}@carbon nanotube sample obtained in this embodiment was characterized by transmission electron microscopy (TEM). Specifically, a small amount of powder sample was placed in an ethanol solution and sonicated for 5 minutes in an ultrasonic disperser to disperse the sample into a suspension. 20 μL of the dispersion was dropped onto a copper mesh microgrid. After adsorption for 3 minutes, the copper mesh was removed with tweezers, and any remaining sample solution was blotted dry with filter paper. TEM observation of the sample on the copper mesh showed that {Ag9} was packed into the carbon nanotubes, and the assembled {Ag9}@carbon nanotube sample had a uniform packing amount. It can be expected that the carbon nanotube confined clusters obtained in this example will catalyze the reduction of p-nitrophenol. The high-angle annular dark-field electron microscopy image of the product obtained in this example is shown below. Figure 2 As shown.

[0093] Example 1

[0094] This example uses the carbon nanotube confined clusters obtained in Material Preparation Example 1 for the catalytic oxidation of sulfides, employing a fixed reaction. Specifically:

[0095] A1. Place 10 mg of the confined carbon nanotube clusters obtained in Material Preparation Example 1 into a clean beaker, add 10 mL of ethanol solution of 10 mmol / L sulfide (diphenyl sulfide; CAS: 139-66-2), and sonicate in an ultrasonic cleaner for 10 minutes to disperse evenly.

[0096] Add 120 μL of 30 wt% hydrogen peroxide solution and a magnetic stir bar to a beaker, seal it with a sealing film, and stir for 1 hour to allow the reaction to proceed fully. This reaction can oxidize sulfide to sulfone.

[0097] A2. Take a small amount of solution with a syringe and filter the carbon nanotube-confined clusters in the solution using a filter head. Perform gas chromatography on the obtained clear solution. The results show that all sulfide substrates in the solution were oxidized to sulfones, indicating that the carbon nanotube-confined clusters provided by this invention can catalyze the oxidation of sulfides to sulfones. Specific test results are as follows: Figure 3 As shown.

[0098] Example 2

[0099] This example uses the carbon nanotube confined clusters obtained in Material Preparation Example 2 for the catalytic reduction of p-nitrophenol. A fixed reaction is employed, specifically:

[0100] A1. Place 2 mg of the carbon nanotube confined clusters obtained in Material Preparation Example 2 into a clean beaker, add 10 mL of 0.5 mmol / L p-nitrophenol aqueous solution, and sonicate in an ultrasonic cleaner for 10 min to disperse evenly.

[0101] Add 7.56 mg of sodium borohydride and a magnetic ball to a beaker, seal it with sealing film, and stir for 6 minutes to allow the reaction to proceed fully. This reaction can reduce p-nitrophenol (CAS: 100-02-7) to p-aminophenol (CAS: 123-30-8).

[0102] A2. Take a small amount of solution with a syringe, filter the metal clusters in the solution using a filter head, and assemble carbon nanotubes. Perform absorption spectroscopy on the resulting clear solution. The results show that p-nitrophenol in the substrate solution was completely reduced to p-aminophenol, indicating that the carbon nanotube confined clusters provided by this invention can catalyze the reduction of p-nitrophenol to p-aminophenol. Specific test results are as follows: Figure 4 As shown.

[0103] Example 3

[0104] This example uses the carbon nanotube confined clusters obtained in Example 2 for the catalytic reduction of p-nitrophenol, employing a flow reaction. Specifically:

[0105] B1. 20 mg of the carbon nanotube confined clusters obtained in Example 2 and 500 mg of activated carbon were stirred evenly in water, and the mixture was rotary evaporated to obtain a powder (catalyst) of metal cluster assembled carbon nanotubes supported on activated carbon; the mesh size of the activated carbon was 40-60 mesh.

[0106] B2. The catalyst obtained in step B1 is fixed in a quartz tube with a diameter of 6 mm, and the catalytic phase is injected using a syringe pump at a flow rate of 5 mL / min. The solute in the catalytic phase includes p-nitrophenol and sodium borohydride, with the concentration of p-nitrophenol being 0.5 mmol / L and the concentration of sodium borohydride being 10 mmol / L.

[0107] The clear, colorless reaction product flowing out of the reactor was collected and subjected to ultraviolet absorption spectroscopy. The results showed that the product was a p-aminophenol solution, indicating that p-nitrophenol could be reduced to p-aminophenol by the carbon nanotube confined clusters provided in Example 2 during the flow reaction. Specific test results are as follows: Figure 5 As shown.

[0108] This example also tested the persistence of the flow reaction, and the results showed that the catalyst could still maintain extremely high activity after 20 liters of reaction flow.

[0109] Comparative Example 1

[0110] In this example, carbon nanotubes were used to catalyze the oxidation of sulfides and the reduction of p-nitrophenol, respectively; wherein:

[0111] The catalytic oxidation reaction of sulfide differs from that in Example 1 in that the carbon nanotube confined clusters in Example 1 are replaced with carbon nanotubes of equal mass.

[0112] The difference between the catalytic reduction reaction of p-nitrophenol and Example 2 is that the carbon nanotube confined clusters used in Example 2 are replaced with carbon nanotubes of equal mass.

[0113] The results show that, in this example, the direct use of single-walled carbon nanotubes resulted in almost no catalytic activity in either the oxidation of thioethers or the reduction of p-nitrophenol. Therefore, the catalytic effect of the carbon nanotube-confined clusters provided in this invention does not directly derive from the carbon nanotubes themselves. Specific test results are as follows... Figures 3-4 As shown.

[0114] Comparative Example 2

[0115] This example directly uses cluster catalysis for the oxidation of sulfides or the reduction of p-nitrophenol, specifically:

[0116] The difference between this example of cluster-catalyzed oxidation of sulfides and Example 1 is that the carbon nanotube-confined clusters in Example 1 are replaced with H3PMo of equal cluster mass. 12 powder;

[0117] The difference between this example of cluster-catalyzed reduction of p-nitrophenol and Example 2 is that the carbon nanotube confined clusters in Example 2 are replaced with (NH4)9Ag9(mba)9 clusters of equal cluster mass.

[0118] The results showed that in the oxidation reaction of sulfides, the catalytic activity of the clusters was significantly lower than that of the carbon nanotube-confined clusters used in Example 1; in the reduction reaction of p-nitrophenol, the direct addition of clusters even led to their decomposition and deactivation. Specific test results are as follows... Figures 3-4 As shown.

[0119] Therefore, it can be seen that the catalytic activity of the carbon nanotube confined clusters provided by the present invention does not directly originate from the clusters.

[0120] As can be seen from Examples 1-2 and Comparative Examples 1-2, the carbon nanotube confined clusters provided by the present invention perform well in heterogeneous catalytic reactions of organic matter, and a synergistic effect occurs between the carbon nanotubes and the clusters.

[0121] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An application of carbon nanotube confined clusters in heterogeneous catalytic reactions, wherein the carbon nanotube confined clusters comprise carbon nanotubes and clusters confined within the carbon nanotubes, characterized in that, The heterogeneous catalytic reactions include the catalytic oxidation of sulfides or the catalytic reduction of nitrophenol; When the heterogeneous catalytic reaction is the catalytic oxidation of sulfides, the clusters are selected from heteropolyacids or heteropolyacid salts; When the heterogeneous catalytic reaction is the catalytic reduction of nitrophenol, the cluster is selected from metal clusters.

2. The application according to claim 1, characterized in that, The heterogeneous catalytic reaction is at least one of a stationary reaction and a mobile reaction.

3. The application according to claim 2, characterized in that, When the heterogeneous catalytic reaction includes the immobilization reaction, the immobilization reaction includes mixing and reacting the carbon nanotube confined clusters, the substrate, and the reaction promoter, followed by separation.

4. The application according to claim 2, characterized in that, When the heterogeneous catalytic reaction includes the flow reaction, the flow reaction includes creating relative motion between the catalyst and the phase to be catalyzed; The catalyst includes a support and the carbon nanotube confinement clusters supported on the support; The phase to be catalyzed includes a substrate and a reaction promoter.

5. The application according to claim 4, characterized in that, During the flow reaction, the catalyst is fixed on the reaction vessel, which includes a quartz tube.

6. The application according to claim 5, characterized in that, The flow reaction is achieved by injecting the phase to be catalyzed into the flow pump, and then flowing through the catalyst in the quartz tube to complete the heterogeneous catalytic reaction.

7. The application according to any one of claims 3 to 6, characterized in that, The substrate includes at least one of thioether and p-nitrophenol.

8. The application according to any one of claims 3 to 6, characterized in that, The reaction aid includes at least one of an oxidizing agent and a reducing agent.

9. The application according to claim 1, characterized in that, When the cluster includes the heteropolyacid, the heteropolyacid is H3PMo. 12 O 40 ; and / or, when the cluster includes the metal cluster, the metal cluster includes (NH4)9Ag9(mba)9.

10. The application according to claim 1, characterized in that, The carbon nanotube confined clusters are prepared by a method including the following steps: S1. The clusters and carbon nanotubes are mixed and assembled in a solvent; S2. The mixture obtained from solid-liquid separation step S1 is washed and dried.

11. The application according to claim 10, characterized in that, In step S1, the temperature of the mixing assembly is 0~100℃; and / or, the duration of the mixing assembly is 10min~15h.

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