A dehydrogenation catalyst, a method for preparing the same, and use thereof
By treating the support with plasma and loading it with noble metals, the problem of insufficient catalyst cycle stability was solved, and the dehydrogenation reaction efficiency and stability of organic liquid hydrogen storage materials were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA UNIV OF GEOSCIENCES (WUHAN)
- Filing Date
- 2024-12-27
- Publication Date
- 2026-05-08
AI Technical Summary
Existing catalysts exhibit a sharp decline in cycle stability after multiple cycles, limiting their application in organic liquid hydrogen storage materials.
A dehydrogenation catalyst was prepared by plasma treatment of the support and then loading it with noble metals. This catalyst was then applied to organic liquid hydrogen storage materials to improve cycle stability.
It improves the catalytic activity of the dehydrogenation reaction and the cycle stability during multiple catalytic reactions, simplifies the preparation process, and reduces costs.
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Figure CN119793449B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of dehydrogenation catalysts, and in particular to a dehydrogenation catalyst, its preparation method, and its application. Background Technology
[0002] Hydrogen is a highly promising green fuel and energy carrier, but its application is limited by the efficiency and safety of storage and transportation. Commonly used hydrogen storage technologies include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, and organic liquid hydrogen storage. Among them, organic liquid hydrogen storage uses organic matter as a hydrogen storage carrier to store and release hydrogen through hydrogenation and dehydrogenation reactions, and has advantages such as high hydrogen storage density and good safety.
[0003] Currently, organic liquid hydrogen storage materials are often used in conjunction with catalysts for dehydrogenation reactions. Carbon nanotubes, as a carbon-based material with a unique structure, are widely used as catalyst supports due to their excellent stability, high selectivity, and good metal-support interaction. However, the catalysts used exhibit a sharp decrease in cycle stability after multiple cycles, limiting their application in practical production. Summary of the Invention
[0004] In view of the shortcomings of the above-mentioned related technologies, the purpose of this application is to provide a dehydrogenation catalyst, its preparation method and application. The dehydrogenation catalyst is prepared by plasma treatment of the support and then loading noble metals, and its application in organic liquid hydrogen storage materials improves the cycle stability of the dehydrogenation reaction.
[0005] Firstly, the method for preparing a dehydrogenation catalyst provided in this application adopts the following technical solution:
[0006] A method for preparing a dehydrogenation catalyst includes the following steps: taking a support and subjecting it to plasma pretreatment with a reaction gas to obtain a pretreated support; loading a noble metal onto the pretreated support to obtain the dehydrogenation catalyst.
[0007] The reacting gas includes one or more of oxidizing gases, reducing gases, and neutral gases.
[0008] Preferably, the reactant gas includes one or more of oxygen, hydrogen, and inert gases.
[0009] Preferably, the reactant gas includes one or more of oxygen, hydrogen, and argon.
[0010] Preferably, the plasma pretreatment includes the following steps: ionizing the reaction gas into plasma and reacting it with the carrier, wherein the flow rate of the reaction gas is 5-15 mL / min.
[0011] Preferably, the flow rate of the reaction gas is 10 mL / min.
[0012] Preferably, the ionization voltage is 80-120V.
[0013] Preferably, the ionization voltage is 100V.
[0014] Preferably, the loading of the noble metal includes the following steps: mixing the pretreated carrier with the precursor and then treating it at high temperature.
[0015] Preferably, the temperature parameters for the high-temperature treatment are 200-250℃ and the treatment time is 1-3h.
[0016] Preferably, the high-temperature treatment is carried out in a reducing atmosphere, which is achieved by a mixture of hydrogen and argon.
[0017] Preferably, the flow rate of the mixed gas is 60-80 mL / min.
[0018] Preferably, the flow rate of the mixed gas is 70 mL / min.
[0019] Preferably, the carrier comprises one or more of carbon nanotubes and activated carbon nanotubes.
[0020] Preferably, the carrier is activated carbon nanotubes.
[0021] Preferably, the activated carbon nanotubes are prepared by the following steps: taking carbon nanotubes, alkali and water, mixing and stirring, drying, then placing them in an inert gas atmosphere and treating them at a temperature of 750-850°C, finally neutralizing them with acid and rinsing them with water until neutral, then drying and grinding them.
[0022] Preferably, the precious metal includes one or more of platinum and palladium.
[0023] Preferably, the noble metal is palladium.
[0024] Preferably, the precursor comprises ammonia and sodium chloropalladium.
[0025] Preferably, the mixing includes mixing and stirring ammonia, sodium chloropalladium, and a pretreatment carrier.
[0026] Secondly, this application provides a dehydrogenation catalyst using the following technical solution:
[0027] A dehydrogenation catalyst is prepared by the above-described method for preparing a dehydrogenation catalyst.
[0028] Thirdly, this application provides the application of a dehydrogenation catalyst in the dehydrogenation reaction of organic liquid hydrogen storage materials.
[0029] Preferably, the method includes the following steps: mixing and heating the organic liquid hydrogen storage material, the dehydrogenation catalyst, and the solvent.
[0030] Preferably, the solvent is mesitylene.
[0031] Preferably, the amount of the dehydrogenation catalyst added is 15-25 wt% of the organic liquid hydrogen storage material.
[0032] Preferably, the amount of the dehydrogenation catalyst added is 20 wt% of the organic liquid hydrogen storage material.
[0033] Preferably, the organic liquid hydrogen storage material includes one or more of perhydronitropropylcarbazole, perhydronitroethylcarbazole, 2-methylindole, and quinoline.
[0034] Preferably, the organic liquid hydrogen storage material is perhydropropylcarbazole.
[0035] In summary, this application includes at least one of the following beneficial technical effects:
[0036] 1. This application prepares a dehydrogenation catalyst by converting the reaction gas into plasma to treat the support, and then loading noble metals onto it. The type and number of functional groups on the surface of the support are controlled, and the application of this catalyst to organic liquid hydrogen storage materials improves the catalytic activity of the dehydrogenation reaction and the cycle stability during multiple catalytic reactions.
[0037] 2. This application improves the dispersion of precious metals by loading them onto a support, while minimizing their aggregation, thereby enhancing the catalytic effect of the dehydrogenation catalyst.
[0038] 3. The preparation method of converting the reaction gas into plasma to treat the support and then loading noble metals is simple to operate and low in cost, which is conducive to the production of dehydrogenation catalysts and the promotion of hydrogen production from organic liquid hydrogen storage materials. Attached Figure Description
[0039] Figure 1 These are comparison diagrams of the XRD diffraction patterns of Examples 2-4 and Comparative Example 2;
[0040] Figure 2 These are comparison diagrams of the XRD diffraction patterns of Examples 2, 5-6, and Comparative Example 1;
[0041] Figure 3 These are comparison diagrams of the infrared spectra of Examples 2-4 and Comparative Example 2;
[0042] Figure 4 This is a comparison chart of the dehydrogenation rate-time curves of Examples 2-4 and Comparative Example 2;
[0043] Figure 5This is a comparison chart of the dehydrogenation rate-time curves of Examples 2, 5-6, and Comparative Example 1;
[0044] Figure 6 This is a comparison graph of the dehydrogenation rate-time curves for 10 cycles in Example 1;
[0045] Figure 7 This is a comparison chart of the dehydrogenation rate-time curves for 10 cycles in Example 2;
[0046] Figure 8 This is a comparison chart of the dehydrogenation rate-time curves for 10 cycles of Comparative Example 1. Detailed Implementation
[0047] The present application will be further described in detail below with reference to the embodiments. The following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified, specific conditions in the following embodiments were performed under conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the methods used are conventional methods known in the art, and the consumables and reagents used are commercially available. Unless otherwise stated, the technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be applied to the present invention.
[0048] The raw materials used in the examples and comparative examples are all commercially available.
[0049] Example 1
[0050] Example 1 of this application provides a dehydrogenation catalyst, which is prepared by the following steps: Carbon nanotubes are spread evenly in a DBD discharge reactor as a support. Oxygen is introduced at a flow rate of 10 mL / min, and the output voltage is controlled at 100 V. After reacting for 2 min, the DBD discharge reactor is turned off, and the carbon nanotubes are stirred evenly and spread evenly in the DBD discharge reactor again. After cooling for 5 min, the DBD discharge reactor is restarted. The reaction and stirring are repeated three times, and then the pretreated support is obtained. 0.495 g of the pretreated support, 10 mL of ammonia water (concentration of 1 mol / L) and 1 mL of sodium chloropalladium (concentration of 5 mg / mL) are mixed and stirred for 12 h, and then placed in an 80℃ constant temperature oil bath to evaporate to dryness for 3 h. Then, the mixture is dried in an oven at 80℃ to obtain a mixed powder. The mixed powder is placed in a tube furnace and heated to 240℃ at a heating rate of 5℃ / min in a mixed gas atmosphere (10% volume fraction of hydrogen and 90% volume fraction of argon). The temperature is kept constant and calcined for 2 h. After cooling, the mixture is ground to obtain the dehydrogenation catalyst.
[0051] Example 2
[0052] Example 2 of this application provides a dehydrogenation catalyst. The difference between Example 2 and Example 1 is that the support in Example 2 is activated carbon nanotubes. The activated carbon nanotubes are prepared by the following steps: 4g of potassium hydroxide and 1g of carbon nanotubes are added to 20mL of ultrapure water and stirred thoroughly. The mixture is then placed in a constant temperature oil bath at 120℃ and evaporated to dryness. The remaining solid is transferred to a tube furnace and heated to 800℃ at a heating rate of 20℃ / min under an argon atmosphere. The temperature is kept constant and calcined for 1h. Finally, the calcined product is added to ultrapure water and 1mol / L hydrochloric acid is added dropwise to neutralize it. The mixture is repeatedly rinsed with ultrapure water until it is neutral, and then dried and ground to obtain activated carbon nanotubes.
[0053] Example 3
[0054] Example 3 of this application provides a dehydrogenation catalyst. The difference between Example 3 and Example 2 is that hydrogen gas is introduced into the DBD discharge reactor in Example 3.
[0055] Example 4
[0056] Example 4 of this application provides a dehydrogenation catalyst. The difference between Example 4 and Example 2 is that argon gas is introduced into the DBD discharge reactor in Example 4.
[0057] Example 5
[0058] Example 5 of this application provides a dehydrogenation catalyst. The difference between Example 5 and Example 2 is that the output voltage of the DBD discharge reactor is controlled to be 80V in Example 5.
[0059] Example 6
[0060] Example 6 of this application provides a dehydrogenation catalyst. The difference between Example 6 and Example 2 is that the output voltage of the DBD discharge reactor is controlled at 120V in Example 6.
[0061] Comparative Example 1
[0062] Comparative Example 1 provides a dehydrogenation catalyst prepared by the following steps: 0.495 g of carbon nanotubes, 10 mL of ammonia water (concentration 1 mol / L), and 1 mL of sodium chloropalladium (concentration 5 mg / mL) were mixed and stirred for 12 h, then placed in an 80 °C constant temperature oil bath to evaporate to dryness for 3 h, and then dried in an oven at 80 °C to obtain a mixed powder. The mixed powder was placed in a tube furnace and heated to 240 °C at a heating rate of 5 °C / min under a mixed gas atmosphere (10% volume fraction of hydrogen and 90% volume fraction of argon), and calcined for 2 h while maintaining a constant temperature. After cooling, it was ground to obtain the dehydrogenation catalyst.
[0063] Comparative Example 2
[0064] Comparative Example 2 provides a dehydrogenation catalyst. The difference between Comparative Example 2 and Comparative Example 1 is that carbon nanotubes are replaced with activated carbon nanotubes in Comparative Example 2.
[0065] Testing and Inspection
[0066] (1) X-ray diffraction was performed on the dehydrogenation catalysts of Examples 2-6 and Comparative Examples 1-2, and the XRD diffraction patterns of Examples 2-4 and Comparative Example 2 of the same batch were compared as follows: Figure 1 As shown (where Example 2 is labeled Pd / C-O2, Example 3 is labeled Pd / C-H2, Example 4 is labeled Pd / C-Ar, and Comparative Example 2 is labeled Pd / C), the XRD diffraction patterns of Examples 2, Examples 5-6, and Comparative Example 1 from the same batch are compared as follows. Figure 2 As shown (where Example 5 is labeled Pd / C-80V, Example 2 is labeled Pd / C-100V, Example 6 is labeled Pd / C-120V, and Comparative Example 1 is labeled Pd / Cu).
[0067] (2) Infrared spectroscopy was performed on the dehydrogenation catalysts of Examples 2-4 and Comparative Example 2. The infrared spectra comparison diagrams of the same batch of Examples 2-4 and Comparative Example 2 are shown below. Figure 3 As shown (where Example 2 is labeled Pd / C-O2, Example 3 is labeled Pd / C-H2, Example 4 is labeled Pd / C-Ar, and Comparative Example 2 is labeled Pd / C).
[0068] (3) The dehydrogenation catalysts of Examples 2-6 and Comparative Examples 1-2 were applied to organic liquid hydrogen storage materials, and the dehydrogenation rate was tested. The specific steps are as follows: 0.2 g of dehydrogenation catalyst, 1.0 g of perhydropropylcarbazole and 3.0 g of mesitylene were added to a three-necked round-bottom flask, placed in an oil bath at 180°C, and the rotation speed was adjusted to 200 r / min to carry out the dehydrogenation reaction. Samples were taken at regular intervals and analyzed using gas chromatography. The dehydrogenation rate-time curves of Examples 2-4 and Comparative Example 2 of the same batch were compared as shown in the figure. Figure 4 As shown (where Example 2 is labeled Pd / C-O2, Example 3 is labeled Pd / C-H2, Example 4 is labeled Pd / C-Ar, and Comparative Example 2 is labeled Pd / C), the dehydrogenation rate-time curves of Examples 2, Examples 5-6, and Comparative Example 1 from the same batch are compared as follows. Figure 5 As shown (where Example 5 is labeled Pd / C-80V, Example 2 is labeled Pd / C-100V, Example 6 is labeled Pd / C-120V, and Comparative Example 1 is labeled Pd / Cu).
[0069] (4) The dehydrogenation catalysts of Examples 1, 2, and Comparative Example 1 were applied to organic liquid hydrogen storage materials, and cyclic dehydrogenation experiments were conducted. The specific steps are as follows: 0.2 g of dehydrogenation catalyst, 1.0 g of perhydropropylcarbazole, and 3.0 g of mesitylene were added to a three-necked round-bottom flask, placed in an oil bath at 180°C, and the rotation speed was adjusted to 200 r / min to carry out the dehydrogenation reaction. After the reaction was completed, the dehydrogenation catalyst was washed with mesitylene until there was no perhydropropylcarbazole or its dehydrogenation product in the washed mesitylene. The same dehydrogenation experiment was repeated 10 times with the washed catalyst. The dehydrogenation rate-time curve comparison of 10 cycles of Example 1 is shown in the figure below. Figure 6 As shown in the figure, the dehydrogenation rate-time curves for 10 cycles in Example 2 are compared. Figure 7 As shown in the figure, the dehydrogenation rate-time curves for 10 cycles of Comparative Example 1 are compared. Figure 8 As shown.
[0070] Results Analysis
[0071] The following combination Figure 1-8 This application will be described in detail.
[0072] Reference Figure 1 and Figure 2 , Figure 1 The effects of plasma treatment of different reactant gases on the crystal structure and phase composition of dehydrogenation catalysts during preparation were investigated. Figure 2 This study investigates the effect of plasma treatment with different output voltages on the crystal structure and phase composition of the dehydrogenation catalyst during its preparation. The results show that palladium nanoparticles are uniformly dispersed on carbon nanotubes, resulting in weaker diffraction peak intensities. However, the graphite diffraction peaks corresponding to the carbon nanotubes before and after treatment show no significant changes, maintaining the original crystal phase structure. This demonstrates that cold plasma treatment has no significant impact on the crystal structure of carbon nanotubes.
[0073] Reference Figure 3 , Figure 3 This study investigated the effect of plasma treatment with different reactant gases on the surface functional groups of the dehydrogenation catalyst during its preparation. The results showed that plasma treatment with oxygen as the reactant gas resulted in the presence of more C=O double bonds (ester, carboxyl, or carbonyl groups) and CO single bonds on the carbon nanotube surface, enhancing the interaction between the active metal palladium and the support.
[0074] Reference Figure 4 and Figure 5 , Figure 4 This study investigates the effect of plasma treatment of different reactant gases during the preparation of dehydrogenation catalysts on the dehydrogenation rate when applied to organic liquid hydrogen storage materials. Figure 5This study investigated the effect of plasma treatment with different output voltages during the preparation of the dehydrogenation catalyst on its dehydrogenation rate when applied to organic liquid hydrogen storage materials. The results showed that Examples 2-6, compared to Comparative Examples 1-2, exhibited significantly improved dehydrogenation rates and dehydrogenation rates when applied to organic liquid hydrogen storage materials. Furthermore, the dehydrogenation catalyst of Example 2, obtained using oxygen as the reactant gas, achieved a dehydrogenation rate of 5.43 wt% after 300 min, realizing complete hydrogen release. Figure 3-5 This indicates that, as in Examples 2-6, plasma treatment of the support followed by loading of noble metals during the preparation of the dehydrogenation catalyst is beneficial to improving the dehydrogenation rate and dehydrogenation efficiency when the dehydrogenation catalyst is applied to organic liquid hydrogen storage materials. Furthermore, using oxygen as the reaction gas to perform plasma treatment on the support enhances the interaction between the active metal palladium and the support, further improving the catalytic effect of the dehydrogenation catalyst as in Example 2.
[0075] Reference Figure 6-8 In Comparative Example 1, when the dehydrogenation catalyst was used to dehydrogenate organic liquid hydrogen storage materials, the dehydrogenation rate decreased significantly from the second cycle onwards. In Example 1, when the dehydrogenation catalyst was used, after 10 cycles, the dehydrogenation rate decreased slightly but was still significantly higher than that of Comparative Example 1. In Example 2, when the dehydrogenation catalyst was used, after 10 cycles, the dehydrogenation rate remained at a level comparable to the first cycle. This indicates that plasma treatment of the support with reactive gas is beneficial for improving the cycle stability of the dehydrogenation catalyst used in the dehydrogenation of organic liquid hydrogen storage materials. Furthermore, using activated carbon nanotubes as a support and plasma treatment of the support with reactive gas has a synergistic effect in improving the cycle stability of the dehydrogenation catalyst used in the dehydrogenation of organic liquid hydrogen storage materials.
[0076] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.
Claims
1. A method for preparing a dehydrogenation catalyst for an organic liquid hydrogen storage material, characterized in that: The process includes the following steps: taking a support and subjecting it to plasma pretreatment with a reaction gas to obtain a pretreated support; loading a noble metal onto the pretreated support to obtain the dehydrogenation catalyst. The reacting gases include oxidizing gases; The carrier is activated carbon nanotubes, which are prepared by the following steps: taking carbon nanotubes, alkali and water, mixing and stirring, drying, then placing them in an inert gas atmosphere and treating them at a temperature of 750-850℃, finally neutralizing them with acid and rinsing them with water until neutral, then drying and grinding them. The plasma pretreatment The process includes the following steps: ionizing the reaction gas into plasma and reacting it with the carrier, wherein the flow rate of the reaction gas is 5-15 mL / min; and the ionization voltage is 80-120 V.
2. The method for preparing a dehydrogenation catalyst for an organic liquid hydrogen storage material according to claim 1, characterized in that: The loading of the precious metal includes the following steps: mixing the pretreated carrier with the precursor and then treating it at high temperature.
3. The method for preparing a dehydrogenation catalyst for an organic liquid hydrogen storage material according to claim 2, characterized in that: The temperature parameters for the high-temperature treatment are 200-250℃, and the treatment time is 1-3 hours.
4. The method for preparing a dehydrogenation catalyst for an organic liquid hydrogen storage material according to claim 1, characterized in that: The precious metals include one or more of platinum and palladium.
5. A dehydrogenation catalyst, characterized in that: It is prepared by the method for preparing the dehydrogenation catalyst of the organic liquid hydrogen storage material according to any one of claims 1-4.
6. The application of a dehydrogenation catalyst as described in claim 5 in the dehydrogenation reaction of organic liquid hydrogen storage materials, characterized in that: Includes the following steps: The organic liquid hydrogen storage material, the dehydrogenation catalyst, and the solvent are mixed and heated.
7. The application of the dehydrogenation catalyst according to claim 6, characterized in that: The amount of the dehydrogenation catalyst added is 15-25 wt% of the organic liquid hydrogen storage material.
Citation Information
Patent Citations
Nano-metal catalyst for hydrogenation and dehydrogenation of liquid organic hydrogen storage material as well as preparation method and application of nano-metal catalyst
CN116060137A