A dehydrogenation catalyst based on indium antimonide quantum dots, and a preparation method and application thereof

Abstract

This invention discloses a dehydrogenation catalyst based on indium antimonide quantum dots, its preparation method, and its application, belonging to the field of organic liquid hydrogen storage catalysis technology. The dehydrogenation catalyst uses indium antimonide (InSb) as the core. By precisely controlling the InSb grain size to 2-5 nm, and utilizing the size effect-induced surface electronic structure reconstruction, InSb quantum dots are prepared and loaded onto a high specific surface area mesoporous carbon support. The catalyst of this invention can efficiently catalyze the dehydrogenation of perhydrodibenzyltoluene to dibenzyltoluene and release hydrogen gas at a low temperature of 120℃. This catalyst utilizes InSb quantum dots, which, due to their abundant defect structure induced by high surface energy and unique electronic properties, achieves efficient polarization of the C-H bond, significantly reducing the activation energy of the dehydrogenation reaction. This solves the technical problems of high cost of traditional noble metal catalysts and high reaction temperature of non-noble metal catalysts, greatly improving the hydrogen transport and release efficiency.

Description

Technical Field

[0001] This invention belongs to the field of organic liquid hydrogen storage catalysis technology, specifically relating to a dehydrogenation catalyst based on indium antimonide quantum dots, its preparation method, and its application. Background Technology

[0002] Hydrogen energy, as a clean energy carrier, plays a crucial role in achieving carbon neutrality. However, the large-scale promotion of the hydrogen economy remains constrained by efficiency and safety bottlenecks in storage and transportation. Organic liquid hydrogen storage (LOHC) technology has emerged to address this challenge. It cleverly utilizes unsaturated organic compounds as hydrogen storage media, leveraging their high volumetric hydrogen storage density, safety during transport at ambient temperature and pressure, and infrastructure compatibility. It is considered an ideal solution for overcoming the challenges of long-distance, large-scale hydrogen storage and transportation. Among these, dibenzyltoluene (DBT) stands out for its excellent thermal stability and cycle durability, becoming a typical representative of the LOHC system; and its dehydrogenation reaction is a key step in achieving efficient and controllable hydrogen utilization.

[0003] Currently, traditional DBT dehydrogenation technology faces a triple challenge: high energy consumption, high cost, and short lifespan. The reaction temperature remains high (250-300℃), and it heavily relies on expensive precious metals (such as Pt and Pd), significantly increasing hydrogen production energy consumption and raising operating costs due to frequent deactivation caused by carbon buildup. While the development of non-precious metal catalysts offers a possibility to break this deadlock, existing alternative materials, limited by the inherent electronic configuration of transition metals, still struggle to meet the stringent standards for industrial applications in key indicators such as low-temperature reactivity, product selectivity, and long-term stability. Summary of the Invention

[0004] Based on the above-mentioned technical problems, this invention proposes a dehydrogenation catalyst based on indium antimonide quantum dots, its preparation method, and its application.

[0005] The technical solution adopted in this invention is: A dehydrogenation catalyst based on indium antimonide quantum dots comprises the following components in parts by weight: 0.3-3 parts of active component, 8-12 parts of support, and 45-55 parts of surface-modified ligand; wherein the active component is indium antimonide quantum dots, the support is mesoporous carbon, and the surface-modified ligand is oleylamine or octadecenoic acid.

[0006] Preferably, the indium antimonide quantum dots have a zincblende crystal structure and a particle size distribution of 2-5 nm.

[0007] Preferably, the mesoporous carbon has a specific surface area of ​​1500~2500 m² / g and a particle size distribution of 5~10 nm.

[0008] A method for preparing the indium antimonide quantum dot-based dehydrogenation catalyst includes the following steps: (1) Add indium source, antimony source and surface-modified ligand to organic solvent, heat to 120~150℃ under nitrogen atmosphere and keep warm for 1~2h to obtain precursor solution; (2) Heat the precursor solution obtained in step (1) to 220~260℃ and keep it at that temperature for 10~30 min to obtain quantum dot colloid; (3) Disperse mesoporous carbon in n-hexane, then add the quantum dot colloid obtained in step (2), stir and reflux at 60~70℃ for 2~3h to obtain quantum dot / mesoporous carbon composite dispersion; (4) Centrifuge the quantum dot / mesoporous carbon composite dispersion obtained in step (3), discard the supernatant, and then wash and dry to obtain the dehydrogenation catalyst based on indium antimonide quantum dots.

[0009] Preferably, in step (1): the indium source is indium acetate or indium chloride, the antimony source is antimony trichloride or antimony acetate, and the organic solvent is octadecene.

[0010] Preferably, in step (1): the mass ratio of the surface-modified ligand to the organic solvent is 0.8~1.2:0.8~1.2; the heating rate is set to 2~4℃ / min.

[0011] Preferably, in step (2), the heating rate is set to 7~9℃ / min.

[0012] Preferably, in step (3), the ratio of the amount of mesoporous carbon, n-hexane and quantum dot colloid is 0.8~1.2g: 90~110mL: 8~12mL.

[0013] A dehydrogenation catalyst based on indium antimonide quantum dots in the catalysis of perhydrodibenzyltoluene ( Applications in dehydrogenation reactions.

[0014] Preferably, the application of the indium antimonide quantum dot-based dehydrogenation catalyst in the catalytic dehydrogenation reaction of perhydrodibenzyltoluene includes the following steps: mixing perhydrodibenzyltoluene with the indium antimonide quantum dot-based dehydrogenation catalyst and reacting at 110~130℃ under an inert atmosphere for 2~4h to achieve the dehydrogenation reaction of perhydrodibenzyltoluene.

[0015] The beneficial technical effects of the present invention are as follows: The catalyst of this invention utilizes the surface defect states (antimony vacancies) of InSb quantum dots as active centers. The quantum size effect endows InSb quantum dots with a large specific surface area and surface dangling bonds, enhancing their ability to... The adsorption capacity of molecules; in the preparation of InSb quantum dots, by controlling the synthesis temperature, antimony (Sb) vacancies are enriched on the surface of the quantum dots. These vacancies, as Lewis acid centers, can polarize and weaken the adsorption capacity of molecules. The CH bonds in the molecule are broken, significantly lowering the reaction energy barrier and enabling bond breaking at low temperatures, thus promoting hydrogen desorption. Mesoporous carbon supports not only provide excellent electron transport channels but also prevent quantum dot aggregation, ensuring the stability of catalytic activity. Specifically: (1) Low temperature efficiency: The catalyst prepared by this invention can achieve efficient dehydrogenation of perhydrodibenzyltoluene at a low temperature of 120℃, which is more than 100℃ lower than the traditional process, and significantly reduces energy consumption.

[0016] (2) High catalytic activity: When the catalyst prepared in this invention is used to catalyze the dehydrogenation reaction of perhydrodibenzyltoluene, the conversion rate of perhydrodibenzyltoluene can reach over 93%, and the selectivity of the target product dibenzyltoluene (DBT) is as high as 95-99.2%, with a cumulative... The release rate is as high as 94-98% of the theoretical value.

[0017] (3) Anti-carbon deposition performance: This invention utilizes the Sb vacancy-induced electron transfer of InSb quantum dots to precisely control the dissociation path of CH bonds - releasing only the CH bonds at the target location. This selective bond breaking effectively suppresses side reactions during dehydrogenation without triggering deep dehydrogenation reactions (such as the destruction of the aromatic ring skeleton). It avoids the formation of unsaturated intermediates, effectively reduces the deposition of carbon precursors, and keeps the catalyst stable during long-term operation.

[0018] (4) Application prospects: The dehydrogenation catalyst based on indium antimonide quantum dots prepared in this invention can be widely used in the field of organic liquid hydrogen storage (LOHC) technology, and is particularly suitable for low-temperature dehydrogenation reaction of LOHC materials such as dibenzyltoluene. This catalyst has broad application prospects in the fields of hydrogen energy storage and transportation, distributed energy systems, and mobile hydrogen sources, and is of great significance for reducing the cost of hydrogen energy storage and transportation and improving the efficiency of hydrogen release.

[0019] (5) Cost advantage: The raw materials are common indium and antimony compounds, which do not contain precious metals, thus greatly reducing the cost of catalysts.

[0020] (6) Environmentally friendly: The reaction conditions are mild and there are few by-products, which is in line with the development direction of green chemistry. Detailed Implementation

[0021] The catalyst prepared in this invention uses indium antimonide (InSb) as the core. By precisely controlling the InSb grain size to 2-5 nm (entering the strong quantum confinement range), and utilizing the size effect-induced surface electronic structure reconstruction, InSb quantum dots are prepared and loaded onto a high specific surface area mesoporous carbon support. The catalyst of this invention can efficiently catalyze the dehydrogenation of perhydrodibenzyltoluene to dibenzyltoluene and release hydrogen gas at a low temperature of 120℃. This catalyst utilizes InSb quantum dots, which, due to their abundant defect structure induced by high surface energy and unique electronic properties, achieves efficient polarization of the CH bond, significantly reducing the activation energy of the dehydrogenation reaction. This solves the technical problems of high cost of traditional noble metal catalysts and high reaction temperature (>250℃) of non-noble metal catalysts, greatly improving the hydrogen transport and release efficiency.

[0022] The surface of InSb quantum dots tends to expose specific crystal planes. On these planes, the Sb atoms, due to their reduced coordination number, experience a shift in their electron binding energy (moving towards lower energies). Furthermore, the formation of Sb vacancies induces lattice reconstruction in the surrounding crystal, creating active sites with unique electronic structures. This Sb vacancy-dominated electronic modulation results in significantly higher intrinsic activity and target product selectivity in catalysis and photoelectrochemical reactions compared to In vacancies.

[0023] The present invention will be further described below with reference to specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means.

[0024] Example 1 Preparation of InSb quantum dot catalysts: (1) Preparation of precursor: 5g oleylamine and 5g octadecene were added to a three-necked flask and nitrogen gas was introduced for protection; then 0.2 mmol indium acetate and 0.2 mmol antimony trichloride were added in sequence, and the temperature was raised to 140℃ at a heating rate of 3℃ / min under nitrogen protection. The mixture was heated and stirred at this temperature for 2h to form a clear precursor solution. (2) Thermal injection nucleation: The above precursor solution was heated to 240°C at a heating rate of 8°C / min and held for 20 min. The solution color changed from colorless to dark black, indicating that InSb quantum dots were generated and quantum dot colloids were obtained. (3) Immobilization: Take 1g of mesoporous carbon (specific surface area 2000 m² / g), disperse it in 100mL of n-hexane, then add 10mL of the above quantum dot colloid, stir and reflux at 68℃ for 3h, so that the quantum dots are anchored on the surface of the carbon support through ligand exchange, and a mixture is obtained. (4) Purification: Centrifuge the above mixture, discard the supernatant, wash three times with ethanol, and dry under vacuum at 60°C for 12 hours to obtain a black powder catalyst (labeled as InSb-QD / C).

[0025] Example 2 Preparation of InSb quantum dot catalysts: (1) Preparation of precursor: 5g oleylamine and 5g octadecene were added to a three-necked flask and nitrogen gas was introduced for protection; then 0.25 mmol indium acetate and 0.25 mmol antimony trichloride were added in sequence, and the temperature was raised to 130℃ at a heating rate of 2℃ / min under nitrogen protection. The mixture was heated and stirred at this temperature for 2h to form a clear precursor solution. (2) Thermal injection nucleation: The above precursor solution was heated to 230°C at a heating rate of 7°C / min and held for 25 min. The solution color changed from colorless to dark black, indicating that InSb quantum dots were generated and quantum dot colloids were obtained. (3) Immobilization: Take 1g of mesoporous carbon (specific surface area 1800 m² / g), disperse it in 100mL of n-hexane, then add 10mL of the above quantum dot colloid, stir and reflux at 68℃ for 3h, so that the quantum dots are anchored on the surface of the carbon support through ligand exchange, and a mixture is obtained. (4) Purification: Centrifuge the above mixture, discard the supernatant, wash three times with ethanol, and dry under vacuum at 60°C for 12 hours to obtain a black powder catalyst (labeled as InSb-QD / C).

[0026] Example 3 Preparation of InSb quantum dot catalysts: (1) Preparation of precursor: 5g oleylamine and 5g octadecene were added to a three-necked flask and nitrogen gas was introduced for protection; then 0.15 mmol indium acetate and 0.15 mmol antimony trichloride were added in sequence, and the temperature was raised to 150℃ at a heating rate of 4℃ / min under nitrogen protection. The mixture was heated and stirred at this temperature for 2h to form a clear precursor solution. (2) Thermal injection nucleation: The above precursor solution was heated to 250°C at a heating rate of 9°C / min and held for 20 min. The solution color changed from colorless to dark black, indicating that InSb quantum dots were generated and quantum dot colloids were obtained. (3) Immobilization: Take 1g of mesoporous carbon (specific surface area 2200 m² / g), disperse it in 100mL of n-hexane, then add 10mL of the above quantum dot colloid, stir and reflux at 68℃ for 3h, so that the quantum dots are anchored on the surface of the carbon support through ligand exchange, and a mixture is obtained. (4) Purification: Centrifuge the above mixture, discard the supernatant, wash three times with ethanol, and dry under vacuum at 60°C for 12 hours to obtain a black powder catalyst (labeled as InSb-QD / C).

[0027] Dehydrogenation performance test Preparation of perhydrodibenzyltoluene: (1) Mix 100g of dibenzyltoluene (DBT) with The catalyst was added to the reactor; after sealing the reactor, it was used... Purge to ensure an oxygen-free environment; (2) Fill the vessel with water at room temperature. Once the initial pressure reaches 40 bar, close the intake valve; (3) Start stirring (800~1000 rpm) and start heating to 160°C; as the temperature rises, the pressure inside the vessel will rise due to the expansion of the gas due to heat. Control the working pressure in the range of 30~50 bar by using a back pressure valve or exhaust strategy. (4) Take samples from the liquid phase sampling port at regular intervals (the sample must be cooled and depressurized to a safe range beforehand) and analyze them by GC-FID or ¹H NMR. Distribution, calculate the degree of hydrogenation (DoH), and consider the reaction endpoint when DoH ≥ 0.97; (5) Stop heating and cool down to below 50°C. Under the protection of an inert atmosphere, slowly and controllably vent excess gas. (Discharge into a compliant exhaust gas treatment system); Open the reactor and filter the slurry while it is still hot (diatomaceous earth filter aid can be used) to remove... Catalyst yields a colorless to pale yellow liquid product, namely perhydrodibenzyltoluene (P2H2O). ).

[0028] Performance testing: (1) Add 10g of perhydrodibenzyltoluene to the autoclave. ) and 0.1g of the InSb-QD / C catalyst prepared in Examples 1-3, sealed the reactor and purged it with nitrogen to replace the air; (2) Place the reactor in an oil bath, heat to 120°C, and stir continuously (500 rpm) for 4 hours; (3) After the reaction is completed, cool to room temperature, analyze the liquid phase product by gas chromatography, collect and calculate the hydrogen volume by water displacement method.

[0029] The performance test results are shown in Table 1.

[0030] Table 1 Performance Test Results

[0031] As shown in Table 1, the InSb-QD / C catalysts prepared in Examples 1-3 were used for catalysis. The dehydrogenation reaction, The dehydrogenation conversion (DoD) was 93.5–96.5%, and the selectivity for the target product dibenzyltoluene (DBT) was 95.6–99.2%; cumulative The release rate reaches 94.7-98% of the theoretical value. The selectivity of the target product dibenzyltoluene (DBT) specifically refers to the proportion of the converted perhydrodibenzyltoluene that generates the target product DBT according to the main reaction pathway.

[0032] Therefore, the InSb-QD / C catalysts prepared in Examples 1-3 all exhibit excellent catalytic performance. This is mainly because indium antimonide (InSb), as a III-V group semiconductor material, possesses excellent properties such as a narrow bandgap (0.17 eV) and high electron mobility. When its size is reduced to the quantum dot level (<10 nm), a significant quantum confinement effect occurs, resulting in extremely high surface atomic coordination unsaturation and exhibiting unique catalytic activity. However, overall, the catalytic performance of Example 1 is the best.

[0033] Comparative Example 1 A commercial Ni / Al2O3 catalyst was used, and other conditions were the same as those described in the performance test. The dehydrogenation conversion rate (DoD) was only 8.3%, indicating that ordinary non-precious metal catalysts are almost inactive at low temperatures.

[0034] Comparative Example 2 Catalyst preparation: Take 1g of mesoporous carbon (specific surface area 2000m² / g), disperse it in 100mL of n-hexane, then add about 47mg of micron-sized InSb particles (10~25μm), stir and reflux at 68℃ for 3h to obtain a mixture; centrifuge the above mixture, discard the supernatant, wash three times with ethanol, and dry under vacuum at 60℃ for 12h to obtain a catalyst supported on micron-sized InSb.

[0035] The catalyst prepared as described above was tested under the same conditions as described above. The dehydrogenation conversion rate (DoD) was only 15.6%, demonstrating that the quantum dot size effect is crucial for low-temperature catalysis.

[0036] For any parts not mentioned in the above embodiments, existing technologies can be adopted or referenced.

[0037] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the above embodiments. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. A dehydrogenation catalyst based on indium antimonide quantum dots, characterized in that, It comprises the following components in parts by weight: 0.3 to 3 parts of active component, 8 to 12 parts of support, and 45 to 55 parts of surface-modified ligand; wherein the active component is indium antimonide quantum dots, the support is mesoporous carbon, and the surface-modified ligand is oleylamine or octadecenoic acid.

2. The dehydrogenation catalyst based on indium antimonide quantum dots according to claim 1, characterized in that, The indium antimonide quantum dots have a zincblende structure and a particle size distribution of 2-5 nm.

3. The dehydrogenation catalyst based on indium antimonide quantum dots according to claim 1, characterized in that, The mesoporous carbon has a specific surface area of ​​1500~2500 m² / g and a particle size distribution of 5~10 nm.

4. The method for preparing the dehydrogenation catalyst based on indium antimonide quantum dots as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Add indium source, antimony source and surface-modified ligand to organic solvent, heat to 120~150℃ under nitrogen atmosphere and keep warm for 1~2h to obtain precursor solution; (2) Heat the precursor solution obtained in step (1) to 220~260℃ and keep it at that temperature for 10~30 min to obtain quantum dot colloid; (3) Disperse mesoporous carbon in n-hexane, then add the quantum dot colloid obtained in step (2), stir and reflux at 60~70℃ for 2~3h to obtain quantum dot / mesoporous carbon composite dispersion; (4) Centrifuge the quantum dot / mesoporous carbon composite dispersion obtained in step (3), discard the supernatant, and then wash and dry to obtain the dehydrogenation catalyst based on indium antimonide quantum dots.

5. The method for preparing the dehydrogenation catalyst based on indium antimonide quantum dots according to claim 4, characterized in that, In step (1): the indium source is indium acetate or indium chloride, the antimony source is antimony trichloride or antimony acetate, and the organic solvent is octadecene.

6. The method for preparing the dehydrogenation catalyst based on indium antimonide quantum dots according to claim 4, characterized in that, In step (1): the mass ratio of the surface-modified ligand to the organic solvent is 0.8~1.2:0.8~1.2; the heating rate is set to 2~4℃ / min.

7. The method for preparing the dehydrogenation catalyst based on indium antimonide quantum dots according to claim 4, characterized in that, In step (2): the heating rate is set to 7~9℃ / min.

8. The method for preparing the dehydrogenation catalyst based on indium antimonide quantum dots according to claim 4, characterized in that, In step (3): the ratio of the amount of mesoporous carbon, n-hexane and quantum dot colloid is 0.8~1.2g: 90~110mL: 8~12mL.

9. The application of the indium antimonide quantum dot-based dehydrogenation catalyst as described in any one of claims 1-3 in the catalytic dehydrogenation reaction of perhydrodibenzyltoluene.

10. The application of the indium antimonide quantum dot-based dehydrogenation catalyst according to claim 9 in the catalytic dehydrogenation reaction of perhydrodibenzyltoluene, characterized in that, The process includes the following steps: mixing perhydrodibenzyltoluene with a dehydrogenation catalyst based on indium antimonide quantum dots and reacting at 110-130°C under an inert atmosphere for 2-4 hours to achieve the dehydrogenation reaction of perhydrodibenzyltoluene.

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