Application of a bimetallic catalyst in the dehydrogenation of dodecahydro-N-ethylcarbazole

Abstract

This invention discloses the application of a bimetallic catalyst in the dehydrogenation of dodecahydro-N-ethylcarbazole, belonging to the field of hydrogen energy storage and transportation technology. The bimetallic catalyst is a magnetic PdCo bimetallic catalyst, comprising an amorphous silicon-oxygen framework and an NCNT-interwoven composite support, and bimetallic nanoparticles supported on the composite support. The application steps include: adding the magnetic PdCo bimetallic catalyst and the reaction substrate dodecahydro-N-ethylcarbazole into a reactor; placing the reactor in a heating device to carry out an isothermal dehydrogenation reaction. This invention utilizes the in-situ grown network structure to reduce mass transfer impedance, weakens product adsorption through electron transfer at the Pd and Co interface, and inhibits metal particle sintering by combining the anchoring effect of defect sites on the support, thereby improving the dehydrogenation rate and cycle stability; after the reaction is completed, the superparamagnetism of the catalyst can be used to achieve separation and recovery by an external magnetic field.

Description

Technical Field

[0001] This invention relates to the field of hydrogen energy storage and transportation technology, specifically to the application of a bimetallic catalyst in the dehydrogenation of dodecahydro-N-ethylcarbazole. Background Technology

[0002] Liquid organic hydrogen carrier technology is one of the technological pathways in the field of hydrogen energy storage and transportation. Among them, dodecahydro-N-ethylcarbazole has become a research subject in this field due to its relatively low dehydrogenation temperature and high mass hydrogen storage capacity. The physicochemical structure of the catalyst directly affects the dehydrogenation efficiency of dodecahydro-N-ethylcarbazole. Although existing supported palladium-based catalysts possess dehydrogenation activity, the dispersion of active sites in the single-metal palladium system is limited, and the electronic structure is difficult to control. Introducing cobalt to construct a bimetallic system can optimize the electronic structure of palladium to some extent, but the overall dehydrogenation efficiency of the catalyst is still limited by the microstructure of the support material.

[0003] Nitrogen-doped carbon nanotubes (CNNTs) are often used as catalyst supports. However, CNNTs synthesized using conventional processes exhibit uneven diameter distribution and are prone to physical aggregation during high-temperature pyrolysis. This structural defect leads to a decrease in the dispersion of subsequently loaded metal nanoparticles, reducing the effective contact area for the catalytic reaction. To control the growth morphology of CNNTs, some existing technologies attempt to introduce mesoporous silica-based materials such as MCM-41 as growth templates. However, the bulk conductivity of mesoporous silica materials is poor. If used directly as the final support, charge transfer during the catalytic process will be hindered. If they are simply physically mixed with carbon and nitrogen sources, the growth process of CNNTs will be randomly disturbed by steric hindrance, making it difficult to form a uniformly distributed and interwoven conductive network structure in situ. Furthermore, after the reaction, micronized carbon-based dehydrogenation catalysts are usually uniformly suspended in liquid organic reaction substrates. Conventional filtration or centrifugation methods are insufficient for efficient catalyst separation, resulting in material loss during the recycling process and increasing the difficulty of recovery operations. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an application of a bimetallic catalyst in the dehydrogenation of dodecylhydro-N-ethylcarbazole, which solves the problems of low catalytic activity, insufficient cycle stability, poor metal dispersion due to uneven growth of nitrogen-doped carbon nanotube supports, and difficulty in separating and recovering catalyst powder in existing dodecylhydro-N-ethylcarbazole dehydrogenation catalysts.

[0005] In a first aspect, the present invention provides an application of a bimetallic catalyst in the dehydrogenation of dodecahydro-N-ethylcarbazole, employing the following technical solution: The application of a bimetallic catalyst in the dehydrogenation of dodecahydro-N-ethylcarbazole, wherein the bimetallic catalyst is a magnetic PdCo bimetallic catalyst, the magnetic PdCo bimetallic catalyst comprising a composite support and bimetallic nanoparticles supported on the composite support; the composite support is a composite support in which an amorphous silica-oxygen framework and NCNTs are interwoven. The application includes the following steps: adding the magnetic PdCo bimetallic catalyst and the reaction substrate dodecahydro-N-ethylcarbazole into a reactor; placing the reactor in a heating device to carry out a constant-temperature dehydrogenation reaction.

[0006] By employing the above technical solution, this invention constructs an in-situ grown composite support and a bimetallic catalytic system, utilizing the synergistic effect between components to improve the dehydrogenation reaction rate and cycle stability. The specific reaction and action process is as follows: 1. Support Formation and Mass Transfer Process: During the catalyst formation stage, the mesoporous channels provided by MCM-41 exert a spatial confinement effect on the precursor components. With increasing temperature, the MCM-41 framework collapses into an amorphous silicon-oxygen structure, guiding the carbon-nitrogen precursors to form carbon nanotubes. This confinement effect hinders the high-temperature aggregation of carbon materials, promoting the interweaving of the amorphous silicon-oxygen framework with NCNTs to form a composite support. The network structure within the composite support provides a high specific surface area and continuous charge transfer channels, shortening the mass transfer path from substrate molecules to the metal center in the dehydrogenation reaction and reducing the internal reaction impedance of the system.

[0007] 2. Metal Particle Anchoring Process: Nitrogen atoms inside the support form topological defects and coordination active sites in the carbon lattice. These coordination active sites anchor the metal nanoparticles through charge interactions, inhibiting the dehydrogenation reaction process and the sintering and agglomeration of metal sites under high-temperature conditions, thus ensuring the dispersion of catalytic active centers.

[0008] 3. Interfacial Electron Transfer Process: After the formation of PdCo bimetallic nanoparticles, due to the difference in electronegativity and work function between Pd and Co elements, interfacial electron transfer occurs from Pd to Co, causing the Pd atoms on the catalyst surface to be in an electron-deficient state. The change in the metal Fermi level modulates the d-band center position of the substrate molecule, weakening the chemisorption energy of dehydrogenation products and reaction intermediates on the noble metal surface. This interfacial electron transfer accelerates the product desorption step, avoids deactivation of active sites due to strong product adsorption, and enhances the initial activity and deep conversion capacity of the catalyst.

[0009] 4. Magnetic field separation process: The specific metallic Co species retained in the catalyst give the overall material superparamagnetism. After the isothermal dehydrogenation reaction is completed, applying an external magnetic field enables the catalyst suspended in the liquid substrate to rapidly polymerize and separate from the system, solving the problems of difficult filtration and easy loss of traditional micronized catalysts.

[0010] Preferably, the magnetic PdCo bimetallic catalyst is prepared by catalytic pyrolysis of raw materials containing MCM-41, melamine and CoCl2 solution; wherein, based on the initial addition amount of Co, the amount of Co added is 10~40 wt.%, and the mass ratio of Co to melamine is 1:5~1:15; the metal loading of Pd in ​​the magnetic PdCo bimetallic catalyst is 0.5~2.0 wt.%.

[0011] More preferably, the initial amount of Co added is 20 wt.%, and the mass ratio of Co to melamine is 1:10; the metal loading of Pd in ​​the magnetic PdCo bimetallic catalyst is 1.0 wt.%.

[0012] By adopting the above technical solution, the material ratio range of the catalyst precursor was clarified. Melamine, as both a carbon and nitrogen source, decomposes and loses mass during pyrolysis. By setting the mass of melamine to be greater than that of Co, sufficient carbon and nitrogen precursors were ensured to generate carbon nanotubes under Co catalysis, thus maintaining the structure of the composite support.

[0013] Preferably, the preparation of the magnetic PdCo bimetallic catalyst includes the following steps: Step 1: Thoroughly mix MCM-41, melamine, and CoCl2 solution, and then dry the mixture to obtain the precursor; Step 2: Place the precursor prepared in Step 1 in a tube furnace and carry out catalytic pyrolysis at 700~900℃ under a nitrogen atmosphere for 2.0~3.0h to obtain the composite support of the amorphous silicon-oxygen framework and NCNT intertwined. Step 3: Disperse the composite support prepared in Step 2 in nitric acid solution and stir; after washing, redisperse it in deionized water, and add sodium borohydride solution dropwise to react; after centrifugation and washing, disperse it again in deionized water, add sodium chloropalladium solution to carry out an electrodisplacement reaction, and after centrifugation, washing and drying, obtain the magnetic PdCo bimetallic catalyst.

[0014] By employing the above technical solution, a complete catalyst synthesis route was constructed. The reaction principle of the preparation steps is as follows: the high-temperature catalytic pyrolysis step promotes the simultaneous collapse of the template and the in-situ growth of carbon nanotubes; nitric acid washing removes excess free metallic Co particles from the surface and also acts as a pore-forming agent; sodium borohydride treatment reduces the oxidized Co species in the system to metallic Co; the subsequent electrodisplacement reaction utilizes the standard electrode potential difference between metallic Co and Pd to allow metallic Co to spontaneously reduce palladium ions in the solution to metallic Pd and deposit them on the support surface, while some Co is oxidized and dissolved, thereby generating uniformly composed PdCo bimetallic nanoparticles.

[0015] Preferably, in step two, catalytic pyrolysis is carried out at 800°C for 2.5 hours.

[0016] Preferably, in step three, the concentration of the nitric acid solution is 0.1M, and the mixture is stirred at 80°C for 0.5 hours; the concentration of the sodium borohydride solution is 0.1M, and the reaction time is 0.5 hours.

[0017] Preferably, in step three, the concentration of the sodium chloropalladium solution is 0.01M, and the electrodisplacement reaction time is 3 hours.

[0018] By adopting the above technical solution, suitable conditions are provided for each stage of catalyst preparation, ensuring the stable growth of the crystal structure and the conduction of the electrochemical replacement reaction.

[0019] Preferably, the magnetic PdCo bimetallic catalyst and the reaction substrate dodecahydro-N-ethylcarbazole are added to the reactor at a molar ratio of nPd:n12H-NEC = 0.3 mol%.

[0020] By adopting the above technical solution, the addition ratio of 0.3 mol% falls within the range of low precious metal loading, which can control the overall application cost of the material while maintaining the system's conversion frequency and dehydrogenation efficiency.

[0021] Preferably, the temperature of the isothermal dehydrogenation reaction is controlled at 150~180℃.

[0022] By employing the above technical solution, a temperature range of 150–180°C provides the activation energy required for the CH bond cleavage of dodecahydro-N-ethylcarbazole. Too low a temperature leads to a slow reaction rate, while too high a temperature increases energy consumption and triggers side reactions. The 150–180°C range ensures that the reaction completes deep dehydrogenation within the set time.

[0023] Preferably, the reactor is a three-necked flask equipped with a reflux condenser and a thermometer. Before adding the reaction substrate dodecahydro-N-ethylcarbazole, an argon gas line is connected to purge the air inside the reactor.

[0024] By adopting the above technical solution, argon gas replacement removes oxygen from the system, preventing oxygen from oxidizing the active metal sites or reacting with the released hydrogen at high temperatures; the reflux condenser prevents the volatilization loss of the liquid organic hydrogen carrier under continuous heating conditions, maintaining the material balance of the reaction system.

[0025] This invention provides an application of a bimetallic catalyst in the dehydrogenation of dodecahydro-N-ethylcarbazole. It offers the following advantages: 1. This invention utilizes MCM-41 as a template to guide the in-situ growth of nitrogen-doped carbon nanotubes, constructing a composite carrier interwoven with an amorphous silicon-oxygen framework and carbon nanotubes. Specific confined channels hinder the aggregation of carbon materials at high temperatures. The interwoven network structure provides continuous charge transfer channels, improving the dispersion of bimetallic nanoparticles and reducing the mass transfer resistance in the dehydrogenation reaction of dodecylhydro-N-ethylcarbazole.

[0026] 2. This invention constructs a PdCo bimetallic catalytic system, utilizing the electronegativity difference between palladium and cobalt to facilitate interfacial electron transfer. The electron-deficient palladium atoms modulate the surface Fermi level, weakening the chemisorption energy of dehydrogenation products on the metal surface and accelerating the desorption process. Combined with the anchoring effect of coordination active sites formed by nitrogen atoms within the support on the metal nanoparticles, sintering of the catalytic active centers during the reaction process is suppressed, thereby improving the rate and cycle stability of the catalytic dehydrogenation reaction.

[0027] 3. The bimetallic catalyst of this invention retains the cobalt species, giving the entire catalytic material paramagnetic properties. After the isothermal dehydrogenation reaction of dodecahydro-N-ethylcarbazole is completed, applying an external magnetic field enables the catalyst suspended in the liquid substrate to rapidly polymerize and separate from the mixture. This magnetic field separation method avoids the physical bottleneck of difficult filtration of conventional micronized catalysts, reduces catalyst material loss, and simplifies the recovery process. Attached Figure Description

[0028] Figure 1 TEM image of the catalyst prepared for the invention; Figure 2 HR-TEM image of the catalyst prepared for the invention; Figure 3 SEM image of the catalyst prepared for the invention; Figure 4 Particle size distribution diagram of metal nanoparticles used to prepare the catalyst for the invention; Figure 5 Cyclic test diagram of the catalyst prepared for the invention in the 12H-NEC catalytic dehydrogenation reaction; Figure 6 Magnetization intensity and magnetic separation diagram of the catalyst prepared for the invention. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Reference Figures 1-6 The main raw materials and reagents used in the following examples and comparative examples are sourced and specified as follows. Reagents not specifically mentioned are all commercially available analytical grade or higher products. Mesoporous molecular sieve MCM-41 is a silica-based mesoporous material, CAS number 7631-86-9. Melamine has the molecular formula C3H6N6, CAS number 108-78-1. Cobalt chloride has the molecular formula CoCl2, CAS number 7646-79-9. Sodium chloropalladium has the molecular formula Na2PdCl4, CAS number 13820-53-6. Dodecahydro-N-ethylcarbazole has the molecular formula C14H27N, CAS number 19430-89-8. All the above raw materials are existing commercially available substances whose chemical structures can be clearly identified by conventional chemical characteristics and can be obtained through conventional commercial channels. Further microstructural descriptions or specific preparation examples are not required.

[0031] Preparation Example 1: This preparation example provides a magnetic PdCo bimetallic catalyst supported on nitrogen-doped carbon nanotubes grown in situ using MCM-41 as a template, comprising the following steps: Step 1: With an initial addition of 20 wt.% of Co and a mass ratio of Co to melamine of 1:10, MCM-41, melamine, and CoCl2 solution were thoroughly mixed and dried to obtain the precursor Co20 / M41-MEL. Step 2: Place the precursor Co20 / M41-MEL prepared in Step 1 in a tube furnace and carry out catalytic pyrolysis at 800℃ under a nitrogen atmosphere for 2.5 h to obtain a composite support Co20 / Si-NCNT with an amorphous silicon-oxygen framework and NCNT interwoven. Step 3: The composite support Co20 / Si-NCNT prepared in Step 2 was dispersed in 0.1M nitric acid solution and stirred at 80℃ for 0.5h. After washing, it was redispersed in deionized water, and 0.1M sodium borohydride solution was added dropwise, and the reaction was carried out for 0.5h. After centrifugation and washing, it was dispersed again in deionized water, and 0.01M sodium chloropalladium solution was added. The metal loading of Pd was controlled at 1.0wt.%, and the electrodisplacement reaction was carried out for 3h. After centrifugation, washing, and drying, the magnetic PdCo bimetallic catalyst was obtained.

[0032] Preparation Example 2: This preparation example provides a magnetic PdCo bimetallic catalyst supported on nitrogen-doped carbon nanotubes grown in situ using MCM-41 as a template, comprising the following steps: Step 1: With an initial addition of 10 wt.% of Co and a mass ratio of 1:5 for Co to melamine, thoroughly mix MCM-41, melamine, and CoCl2 solution, and then dry the mixture to obtain the precursor. Step 2: The precursor prepared in Step 1 is placed in a tube furnace and catalytically pyrolyzed at 700°C under a nitrogen atmosphere for 2.0 h to obtain a composite support with an amorphous silicon-oxygen framework interwoven with NCNT. Step 3: The composite support prepared in Step 2 was dispersed in 0.1M nitric acid solution and stirred at 80℃ for 0.5h. After washing, it was redispersed in deionized water, and 0.1M sodium borohydride solution was added dropwise, and the reaction was carried out for 0.5h. After centrifugation and washing, it was dispersed again in deionized water, and 0.01M sodium chloropalladium solution was added. The metal loading of Pd was controlled at 0.5wt.%, and the electrodisplacement reaction was carried out for 3h. After centrifugation, washing, and drying, the magnetic PdCo bimetallic catalyst was obtained.

[0033] Preparation Example 3: This preparation example provides a magnetic PdCo bimetallic catalyst supported on nitrogen-doped carbon nanotubes grown in situ using MCM-41 as a template, comprising the following steps: Step 1: With an initial addition of 40 wt.% of Co and a mass ratio of Co to melamine of 1:15, MCM-41, melamine, and CoCl2 solution are thoroughly mixed and dried to obtain the precursor. Step 2: The precursor prepared in Step 1 is placed in a tube furnace and catalytically pyrolyzed at 900°C under a nitrogen atmosphere for 3.0 h to obtain a composite support with an amorphous silicon-oxygen framework interwoven with NCNT. Step 3: The composite support prepared in Step 2 was dispersed in 0.1M nitric acid solution and stirred at 80℃ for 0.5h. After washing, it was redispersed in deionized water, and 0.1M sodium borohydride solution was added dropwise, and the reaction was carried out for 0.5h. After centrifugation and washing, it was dispersed again in deionized water, and 0.01M sodium chloropalladium solution was added. The metal loading of Pd was controlled at 2.0wt.%, and the electrodisplacement reaction was carried out for 3h. After centrifugation, washing, and drying, the magnetic PdCo bimetallic catalyst was obtained. Example

[0034] This embodiment provides an application of a bimetallic catalyst in the dehydrogenation of dodecahydro-N-ethylcarbazole, comprising the following steps: adding the magnetic PdCo bimetallic catalyst prepared in Preparation Example 1 and the reaction substrate dodecahydro-N-ethylcarbazole to a reactor at a molar ratio of nPd:n12H-NEC=0.3mol%; and placing the reactor in an oil bath heating device at 180°C for isothermal dehydrogenation reaction. Example

[0035] This embodiment provides an application of a bimetallic catalyst in the dehydrogenation of dodecahydro-N-ethylcarbazole, comprising the following steps: adding the magnetic PdCo bimetallic catalyst prepared in Preparation Example 2 and the reaction substrate dodecahydro-N-ethylcarbazole to a reactor at a molar ratio of nPd:n12H-NEC=0.3mol%; and placing the reactor in an oil bath heating device at 150°C for isothermal dehydrogenation reaction. Example

[0036] This embodiment provides an application of a bimetallic catalyst in the dehydrogenation of dodecahydro-N-ethylcarbazole, comprising the following steps: adding the magnetic PdCo bimetallic catalyst prepared in Preparation Example 3 and the reaction substrate dodecahydro-N-ethylcarbazole to a reactor at a molar ratio of nPd:n12H-NEC=0.3mol%; and placing the reactor in an oil bath heating device at 165°C for isothermal dehydrogenation reaction.

[0037] Comparative Example 1: Compared with Example 1, the difference is that MCM-41 was not added in step one of the catalyst preparation process, but the rest are the same.

[0038] Comparative Example 2: Compared with Example 1, the difference is that CoCl2 solution was not added in step one of the catalyst preparation, and an electrochemical displacement reaction was not carried out in step three. Instead, an equal amount of Pd (i.e., containing only single metal Pd) was directly loaded using the conventional impregnation reduction method. All other aspects are the same.

[0039] Comparative Example 3: Compared with Example 1, the difference is that sodium chloropalladium solution was not added in step three of the catalyst preparation process for electrochemical displacement reaction (i.e., only single metal Co was included), while the rest were the same.

[0040] Comparative Example 4: Compared with Example 1, the difference is that in step one of the catalyst preparation, melamine is replaced with an equal mass of glucose (i.e., ordinary carbon nanotubes without nitrogen doping are prepared using a nitrogen-free carbon source), and the rest are the same.

[0041] Comparative Example 5: Compared with Example 1, the difference is that the in-situ growth of the support was not carried out when preparing the catalyst. Instead, the MCM-41 that has been pyrolyzed at high temperature was physically mixed with conventional commercial nitrogen-doped carbon nanotubes as the support. All other aspects are the same.

[0042] Test Example 1: A three-necked flask equipped with a reflux condenser and thermometer was used as the reactor. An argon gas line was connected to purge the air from the reactor. Dodecylhydro-N-ethylcarbazole was added to the reactor along with a catalyst, maintaining a molar ratio of active metal Pd to dodecylhydro-N-ethylcarbazole of 0.3 mol%. Magnetic stirring was activated, and the reactor was placed in a 180°C constant-temperature oil bath. The reaction reached its zero point when the temperature stabilized at 180°C. At 1 hour, 3 hours, and 6 hours, a microsyringe was used to transfer a sample of the reaction mixture, which was then diluted with cyclohexane. The diluted sample was injected into a gas chromatograph, and the product was quantitatively analyzed using a flame ionization detector. Qualitative analysis was performed based on retention time, and the substrate conversion rate and dehydrogenation efficiency were calculated. The initial rate of the reaction system in the steady-state phase was recorded to calculate the conversion frequency.

[0043] Table 1 Catalytic performance data of each catalyst in the dehydrogenation reaction of dodecahydro-N-ethylcarbazole.

[0044] Comparing the data from Example 1 and Comparative Example 1, the differences highlight the structure-guiding effect of the MCM-41 template. During preparation, the mesoporous channels provided by MCM-41 create a spatial confinement effect on the active components, and the amorphous silicon-oxygen framework formed by pyrolysis and reconstruction guides the carbon-nitrogen precursors to form carbon nanotubes. Comparative Example 1 lacks the physical barrier confinement of the template, resulting in the aggregation and growth of carbon materials at high temperatures. This leads to a reduction in the effective specific surface area of ​​the composite support, a decrease in the dispersion of metal particles, and a decline in dehydrogenation efficiency.

[0045] Compared with Comparative Examples 4 and 5, Example 1 exhibits higher initial activity and deep conversion capability, corresponding to the in-situ growth of the support and the heteroatom doping mechanism. Nitrogen atoms introduced by melamine pyrolysis form topological defects and coordination active sites within the carbon lattice. These sites anchor precursor ions and reduced metal nanoparticles through charge interactions, inhibiting the sintering growth of metal sites during high-temperature pyrolysis and the reaction process. Simultaneously, the in-situ interwoven silicon-oxygen and carbon nanotube network shortens the mass transfer path from reactant molecules to the metal center, reducing the charge transfer impedance within the system. Comparative Example 4, using a nitrogen-free carbon source, cannot provide sufficient lattice defects for metal anchoring; the physical mixing method in Comparative Example 5 fails to form continuous interfacial bonding, resulting in limited reactant activation and mass transfer.

[0046] The data comparison between Example 1 and Comparative Examples 2 and 3 demonstrates the electronic modulation mechanism of the PdCo bimetallic system. After the formation of bimetallic nanoparticles, due to the difference in electronegativity and work function between elements, there is interfacial electron transfer from Pd to Co in the system, resulting in Pd atoms on the catalyst surface being in an electron-deficient state. The change in the Fermi level modulates the d-band center position of the substrate molecule, weakens the chemisorption energy of dehydrogenation products and reaction intermediates on the noble metal surface, and accelerates the desorption step. The single-metal Pd system (Comparative Example 2) lacks an electronic modulation pathway and is prone to active site poisoning due to strong product adsorption; the single-metal Co system (Comparative Example 3) is limited by intrinsic catalytic activity and cannot effectively break the CH bond of the substrate, and the reaction rates of both are lower than those of Example 1.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. The application of a bimetallic catalyst in the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, The bimetallic catalyst is a magnetic PdCo bimetallic catalyst, which comprises a composite support and bimetallic nanoparticles supported on the composite support; the composite support is a composite support in which an amorphous silicon-oxygen framework and NCNTs are interwoven. The application includes the following steps: adding the magnetic PdCo bimetallic catalyst and the reaction substrate dodecahydro-N-ethylcarbazole into a reactor; placing the reactor in a heating device to carry out a constant-temperature dehydrogenation reaction.

2. The application of the bimetallic catalyst according to claim 1 in the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, The magnetic PdCo bimetallic catalyst is prepared by catalytic pyrolysis of raw materials containing MCM-41, melamine and CoCl2 solution; wherein, based on the initial amount of Co added, the amount is 10~40 wt.%, and the mass ratio of Co to melamine is 1:5~1:15; the metal loading of Pd in ​​the magnetic PdCo bimetallic catalyst is 0.5~2.0 wt.%.

3. The application of the bimetallic catalyst according to claim 2 in the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, The initial amount of Co is 20 wt.%, and the mass ratio of Co to melamine is 1:10; the metal loading of Pd in ​​the magnetic PdCo bimetallic catalyst is 1.0 wt.%.

4. The application of the bimetallic catalyst according to claim 1 in the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, The preparation of the magnetic PdCo bimetallic catalyst includes the following steps: Step 1: Thoroughly mix MCM-41, melamine, and CoCl2 solution, and then dry the mixture to obtain the precursor; Step 2: Place the precursor prepared in Step 1 in a tube furnace and carry out catalytic pyrolysis at 700~900℃ under a nitrogen atmosphere for 2.0~3.0h to obtain the composite support of the amorphous silicon-oxygen framework and NCNT intertwined. Step 3: Disperse the composite support prepared in Step 2 in nitric acid solution and stir; after washing, redisperse it in deionized water, and add sodium borohydride solution dropwise to react; after centrifugation and washing, disperse it again in deionized water, add sodium chloropalladium solution to carry out an electrodisplacement reaction, and after centrifugation, washing and drying, obtain the magnetic PdCo bimetallic catalyst.

5. The application of the bimetallic catalyst according to claim 4 in the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, In step two, catalytic pyrolysis is carried out at 800℃ for 2.5 hours.

6. The application of the bimetallic catalyst according to claim 4 in the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, In step three, the concentration of the nitric acid solution is 0.1M, and the mixture is stirred at 80°C for 0.5 hours; the concentration of the sodium borohydride solution is 0.1M, and the reaction time is 0.5 hours.

7. The application of the bimetallic catalyst according to claim 4 in the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, In step three, the concentration of the sodium chloropalladium solution is 0.01M, and the electrodisplacement reaction takes 3 hours.

8. The application of the bimetallic catalyst according to claim 1 in the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, The magnetic PdCo bimetallic catalyst and the reaction substrate dodecahydro-N-ethylcarbazole were added to the reactor at a molar ratio of nPd:n12H-NEC = 0.3 mol%.

9. The application of the bimetallic catalyst according to claim 8 in the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, The temperature of the isothermal dehydrogenation reaction is controlled at 150~180℃.

10. The application of the bimetallic catalyst according to claim 9 in the dehydrogenation of dodecahydro-N-ethylcarbazole, characterized in that, Before adding the reaction substrate dodecahydro-N-ethylcarbazole, argon gas is introduced to purge the air in the reactor; and the isothermal dehydrogenation reaction is carried out in a reactor with condensation reflux conditions.

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