A liquid hydrogen storage material and hydrogen storage process

Abstract

This application discloses a liquid hydrogen storage material and a hydrogen storage process. The liquid hydrogen storage material comprises the following components in parts by weight: 30-60 parts of component A, 40-70 parts of component B, and 0.1-0.5 parts of stabilizing agent, including tetraisopropyl titanate and 2,6-di-tert-butyl-p-cresol; wherein the combination of component A and component B is any one of the following: component A is N-isopropylindole, component B is N-isopropylcarbazole; component A is N-propylindole, component B is N-propylcarbazole; component A is N-isopropylindole, component B is N-propylindole; component A is N-propylcarbazole, component B is N-isopropylcarbazole. The hydrogen storage process includes: pressurizing hydrogen to 70-80 bar and raising the temperature to 130-160°C, and reacting it with the above-mentioned liquid hydrogen storage material through a noble metal hydrogenation catalyst to obtain a hydrogen storage liquid, thereby achieving a superior hydrogen storage effect.

Description

Technical Field

[0001] This application relates to the field of liquid hydrogen storage materials technology, and in particular to a liquid hydrogen storage material and a hydrogen storage process. Background Technology

[0002] Hydrogen energy is considered an ideal energy source due to its abundant resources, lack of pollution, renewability, and high energy density. In recent years, with the shortage of fossil fuels, environmental requirements, and pressure for sustainable development, the development and utilization of hydrogen energy has become increasingly important. Hydrogen storage technologies can be divided into physical and chemical methods. Physical methods mainly include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, and physical adsorption hydrogen storage. Chemical methods mainly include metal alloy hydrogen storage and organic liquid hydrogen storage. Among these, organic liquid hydrogen storage technology has attracted widespread attention due to its high hydrogen storage density, relatively safe storage and transportation conditions, and good reversibility. This technology is typically based on the reversible hydrogenation and dehydrogenation reactions of unsaturated organic compounds (such as toluene and naphthalene) to achieve hydrogen storage and release, forming a hydrogen storage system with liquid organic hydrogen carriers as the core.

[0003] Organic liquid hydrogen storage materials have insufficient hydrogen storage performance and are prone to generating byproducts during hydrogenation / dehydrogenation cycles. Furthermore, the catalyst support is prone to side reactions such as cracking and polymerization during repeated hydrogenation / dehydrogenation cycles, leading to a decrease in hydrogen storage performance. Summary of the Invention

[0004] To address the issue of insufficient hydrogen storage performance of organic liquid hydrogen storage materials, a liquid hydrogen storage material and hydrogen storage process are provided.

[0005] The first inventive objective of this invention is achieved through the following technical solution:

[0006] A liquid hydrogen storage material, comprising the following components in parts by weight:

[0007] Component A: 30-60 portions

[0008] 40-70 parts of component B

[0009] Stabilizing agent 0.1-0.5 parts,

[0010] Stabilizing agents include tetraisopropyl titanate and 2,6-di-tert-butyl-p-cresol;

[0011] The combination of component A and component B can be any of the following:

[0012] (a) Component A is N-isopropylindole, and component B is N-isopropylcarbazole;

[0013] (b) Component A is N-propylindole, and component B is N-propylcarbazole;

[0014] (c) Component A is N-isopropylindole, and component B is N-propylindole;

[0015] (d) Component A is N-propylcarbazole, and component B is N-isopropylcarbazole.

[0016] By adopting the above technical solution, N-alkyl-substituted indole or carbazole derivatives have an aromatic ring in their molecular structure, and their π-electron system can serve as active sites for hydrogen storage. Under hydrogenation conditions, the unsaturated double bonds on the aromatic ring are partially or completely saturated with hydrogen, forming corresponding hydrogenation products, thereby storing hydrogen in the molecule in the form of chemical bonding. When hydrogen needs to be released, the hydrogenation products can be reversibly decomposed through a dehydrogenation reaction, regenerating the unsaturated parent structure and releasing hydrogen.

[0017] The electron-donating inductive effect of alkyl groups can regulate the electron cloud density of aromatic heterocycles, affecting the thermodynamic equilibrium and kinetic rate of their hydrogenation reactions. This typically helps reduce the enthalpy change of dehydrogenation reactions, allowing the dehydrogenation process to proceed under relatively mild conditions. Alkyl chains provide necessary steric hindrance and intermolecular force regulation, effectively lowering the melting point and viscosity of the mixture, keeping the material liquid within the operating temperature range. Carbazole components, due to their larger conjugated system, have a higher hydrogen storage capacity than indole components. Combination (a) consists of N-isopropylindole and N-isopropylcarbazole, both containing branched isopropyl groups, which effectively suppress intermolecular π-π stacking and improve low-temperature fluidity. The mixture of indole and the higher-capacity carbazole shows good matching in electronic effects and reaction thermodynamics, broadening the liquid phase temperature range. The system is optimized to achieve a combination of high capacity and excellent low-temperature performance, resulting in a homogeneous and stable system. Combination (b) consists of N-propylindole and N-propylcarbazole. The straight-chain alkyl group provides similar electronic effects but has less steric hindrance, which is conducive to close molecular arrangement and obtains higher density. While maintaining the hydrogen storage capacity, it has a lower synthesis cost. Combination (c) consists of N-propylindole and N-isopropylindole. Both are indole compounds, which makes the hydrogenation / dehydrogenation reaction homogeneous. The straight chain and branched propyl group produce a low eutectic effect, which reduces the freezing point of the mixture and improves the low-temperature fluidity, reaction homogeneity and cycle stability. Combination (d) consists of N-isopropylcarbazole and N-propylcarbazole. The blending of the two isomers can destroy the strong intermolecular interaction of the rigid carbazole ring and improve the low-temperature fluidity.

[0018] Tetraisopropyl titanate, as a Lewis acid precursor, can weakly interact with nitrogen atoms in nitrogen-containing heterocycles, catalyzing the activation of CH bonds, promoting hydrogenation reactions, and stabilizing reaction intermediates. This helps to suppress excessive reactions in hydrogenation / dehydrogenation cycles and maintain catalyst activity. 2,6-Di-tert-butyl-p-cresol is a highly efficient hindered phenolic antioxidant that reacts with reactive intermediates such as peroxide radicals and alkyl radicals generated during hydrogenation / dehydrogenation cycles or storage, quenching free radical chain reactions and reducing the formation of irreversible byproducts. Tetraisopropyl titanate inhibits deep side reactions along the reaction pathway, while the antioxidant prevents material degradation at the level of terminating free radical chains, improving the chemical stability of hydrogen storage materials and enhancing hydrogen storage performance.

[0019] Optionally, the mass ratio of tetraisopropyl titanate to 2,6-di-tert-butyl-p-cresol is 1:(1-3).

[0020] By adopting the above technical solution, within this range, the amount of 2,6-di-tert-butyl-p-cresol can eliminate free radicals generated in the system, and tetraisopropyl titanate can not only play its role in regulating the reaction pathway and inhibiting deep side reactions, but also reduce the potential catalytic side effects and adverse effects caused by the introduction of metal ions.

[0021] Optionally, 0.1-0.5 parts of nano-cerium oxide may also be added.

[0022] By adopting the above technical solution, the surface of nano-cerium oxide has abundant oxygen vacancies, and Ce ions can reversibly change between the +3 and +4 valence states. In the hydrogenation / dehydrogenation cycle environment of hydrogen storage materials, oxygen vacancies can serve as active sites, adsorbing and activating hydrogen molecules or reaction intermediates, thereby promoting hydrogen overflow. That is, hydrogen atoms migrate from the surface of noble metal catalysts to oxide supports and then to organic molecules, improving the overall hydrogenation reaction effect. Furthermore, nano-cerium oxide has excellent oxygen storage and release capabilities and free radical scavenging capabilities, enabling it to reversibly capture and release oxygen, effectively reducing reactive oxygen species and carbon-center free radicals, and improving the stability of hydrogen storage materials.

[0023] The second objective of this invention is achieved through the following technical solution:

[0024] A hydrogen storage process includes the following steps: pressurizing hydrogen to 70-80 bar and reacting it with the above-mentioned liquid hydrogen storage material at a temperature of 130-160°C using a noble metal hydrogenation catalyst to obtain a hydrogen storage liquid.

[0025] By adopting the above technical solution, liquid hydrogen storage materials undergo hydrogenation reactions in the presence of noble metal hydrogenation catalysts. The catalysts reduce the activation energy of the reaction, enabling hydrogenation to proceed efficiently under relatively mild conditions. Throughout the process, high pressure, medium temperature, and the catalyst work together to achieve rapid and high-conversion hydrogen storage.

[0026] Optionally, the noble metal hydrogenation catalyst is a Ru / N-CNT catalyst.

[0027] By employing the above technical solution, ruthenium (Ru) is a highly efficient hydrogenation metal. Its d-electron orbitals can effectively break HH bonds to generate adsorbed hydrogen atoms. Nitrogen-doped carbon nanotubes (N-CNTs) serve as a support, and their high specific surface area and hollow structure provide abundant anchoring sites. Nitrogen doping introduces defects such as graphitic nitrogen and pyridine nitrogen, modulating the electronic structure of carbon, enhancing the adhesion and dispersion of ruthenium nanoparticles, and preventing agglomeration. The alkaline surface of N-CNTs promotes heterolytic hydrogen cleavage, while ruthenium particles promote homolytic cleavage. The two work synergistically to achieve multi-path activation of hydrogen. In the Ru / N-CNT catalyst, after hydrogen molecules dissociate into hydrogen atoms on the ruthenium surface, they migrate to the nitrogen active sites on the N-CNT surface through the hydrogen spillover effect, which is beneficial for the rapid transfer of hydrogen atoms to the unsaturated bonds of the liquid organic support. At the same time, the conductivity of N-CNTs promotes electron transfer, optimizes the electronic state of ruthenium, and improves hydrogenation selectivity. The catalyst achieves efficient hydrogen activation and transfer, enhancing the hydrogen storage effect.

[0028] Optionally, the mass ratio of Ru / N-CNT catalyst to liquid hydrogen storage material is (0.5-1):100.

[0029] By adopting the above technical solution, at this ratio, the catalyst provides sufficient active sites to cover the hydrogenatable sites in the liquid hydrogen storage material, which is beneficial for the rapid hydrogenation reaction; at the same time, it helps to reduce the problem of insufficient active sites and limited reaction rate when the ratio is too low; and it helps to reduce the problem of catalyst aggregation and reduced effective surface area when the ratio is too high.

[0030] Optionally, the Ru / N-CNT catalyst has a Ru loading of 1-6 wt%.

[0031] By adopting the above technical solutions, within this range, it is beneficial to reduce the problem of low catalytic efficiency due to the scarcity of active sites when the loading is too low; and it is also beneficial to reduce the problem of particle agglomeration and increased size due to excessive loading, which reduces the active surface area and blocks the N-CNT channels, so that the Ru / N-CNT catalyst has high specific activity, improves the hydrogenation reaction efficiency, and enhances the hydrogen storage effect.

[0032] Optionally, the Ru precursor used in the preparation of the Ru / N-CNT catalyst is ruthenium acetylacetonate.

[0033] By adopting the above technical solution, during the pyrolysis of ruthenium acetylacetonate, the acetylacetonate ligands are gradually removed, reducing ruthenium ions to form metallic ruthenium nanoparticles. The carbon residue generated by ligand decomposition helps the ruthenium particles bind to the N-CNT surface, enhancing the anchoring force. Compared with other precursors such as ruthenium chloride, ruthenium acetylacetonate does not contain halogen impurities, avoiding catalyst poisoning or corrosion problems. Moreover, the chelating properties of the acetylacetonate ligands allow for uniform adsorption on the support surface, providing a slow-release reduction environment during pyrolysis to form ruthenium nanoparticles with uniform size and narrow distribution. At the same time, the ligand-derived carbon layer may protect the ruthenium particles from oxidation or sintering. The Ru / N-CNT catalyst prepared using ruthenium acetylacetonate exhibits high dispersibility, high activity, and excellent stability, improving hydrogen storage performance.

[0034] In summary, this application has at least the following beneficial effects:

[0035] (1) N-alkyl-substituted indole or carbazole derivatives achieve reversible chemical hydrogen storage through their aromatic ring π-electron system. When hydrogen is added, the double bond is saturated to form hydrogenated products, and when dehydrogenated, they decompose to release hydrogen gas.

[0036] (2) Tetraisopropyl titanate, as a Lewis acid precursor, catalyzes the activation of CH bonds, promotes hydrogenation and stabilizes intermediates to suppress side reactions; the antioxidant 2,6-di-tert-butyl-p-cresol quenches free radical chain reactions, reduces material degradation, reduces side reactions that occur in the material, and improves hydrogen storage performance. Detailed Implementation

[0037] raw material

[0038] N-Isopropylindole, specifically 1-isopropyl-1H-indole, with a purity of 97 wt%, was purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.

[0039] N-Isopropylcarbazole, specifically 9-isopropyl-9H-carbazole, with a purity of 97 wt%, was purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.

[0040] N-propylindole, specifically 1-propyl-1H-indole, with a purity of 95 wt%, was purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.

[0041] N-propylcarbazole, specifically 9-propyl-9H-carbazole, with a purity of 95 wt%, was purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.

[0042] 2,6-Di-tert-butyl-p-cresol, purity 98 wt%, purchased from Shanghai Bid Pharmaceutical Technology Co., Ltd.

[0043] Tetraisopropyl titanate, purity 99.99 wt%, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0044] Nano-cerium oxide, 20-50nm, spherical, 99.5wt% purity, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0045] Nitrogen-doped carbon nanotubes, with an outer diameter of 30-80 nm and a length of 10-30 µm, were purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0046] Ruthenium acetylacetonate, 99.95 wt% purity, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0047] Acetone and RuCl·3H2O were both commercially available.

[0048] Preparation Example 1

[0049] A Ru / N-CNT catalyst, the preparation method of which is as follows:

[0050] 100g of nitrogen-doped carbon nanotubes (N-CNTs) were added to 15L of 6M concentrated nitric acid and refluxed in an oil bath at 120℃ for 6h. After cooling to room temperature (25℃), the filter cake was obtained by centrifugation and filtration at 8000 rpm for 10min. The filter cake was washed three times with deionized water and placed in a vacuum drying oven and dried at -0.095MPa vacuum and 80℃ for 12h to obtain pretreated N-CNT powder.

[0051] 11.82 g of ruthenium acetylacetone was added to 5 L of acetone and stirred at 300 rpm for 30 min in a 40 °C water bath to obtain a precursor solution. 100 g of pretreated N-CNT powder was added to the precursor solution, and the mixture was stirred at 300 rpm for 6 h in a 40 °C water bath under light-protected conditions to obtain a suspension. The suspension was then treated on a rotary evaporator for 3 h to remove the solvent. The water bath temperature was 40 °C and the rotation speed was 100 rpm to obtain a paste. The paste was placed in a vacuum drying oven and dried at -0.095 MPa vacuum and 40 °C for 12 h. Finally, it was placed in a tube furnace and dried at 200 °C. Argon gas was introduced into the sccm and held for 40 min. The temperature was increased to 200℃ at 2℃ / min and held for 30 min. The temperature was then increased to 350℃ at 3℃ / min and held for 1 h. The temperature was then increased to 500℃ at 5℃ / min and held for 2 h. The heating was then stopped and the temperature was allowed to cool naturally to 80℃ to obtain the Ru / N-CNT catalyst.

[0052] Preparation Example 2

[0053] A Ru / N-CNT catalyst, which differs from Preparation Example 1 in that: the amount of ruthenium acetylacetone is 3.94 g; the rest of the amount is the same as in Preparation Example 1.

[0054] Preparation Example 3

[0055] A Ru / N-CNT catalyst, which differs from Preparation Example 1 in that: the amount of ruthenium acetylacetone is 23.64 g; the rest is the same as in Preparation Example 1.

[0056] Preparation Example 4

[0057] A Ru / N-CNT catalyst, which differs from Preparation Example 1 in that: the amount of ruthenium acetylacetone is 3g; the rest of the amount is the same as in Preparation Example 1.

[0058] Preparation Example 5

[0059] A Ru / N-CNT catalyst, which differs from Preparation Example 1 in that: the amount of ruthenium acetylacetone is 25g; the rest of the amount is the same as in Preparation Example 1.

[0060] Preparation Example 6

[0061] A Ru / N-CNT catalyst, which differs from Preparation Example 1 in that 7.79 g of RuCl·3H2O is used instead of 11.82 g of ruthenium acetylacetonate; the rest is the same as Preparation Example 1.

[0062] Preparation Example 7

[0063] A liquid hydrogen storage material is prepared as follows: 50 kg of N-isopropylindole and 50 kg of N-isopropylcarbazole are mixed and heated in an oil bath at 80°C for 30 min while stirring at 300 rpm to obtain the main mixture. The main mixture is then heated in an oil bath at 80°C. 200 g of 2,6-di-tert-butyl-p-cresol is added and stirred at 300 rpm for 10 min. Heating is then stopped, and the mixture is allowed to cool naturally to room temperature (25°C). 100 g of tetraisopropyl titanate is added and stirred at 500 rpm for 15 min. 300 g of nano-cerium oxide is added and stirred at 500 rpm for 30 min to obtain the liquid hydrogen storage material.

[0064] Preparation Example 8

[0065] A liquid hydrogen storage material, which differs from Preparation Example 7 in that: tetraisopropyl titanate is not added, and 300g of 2,6-di-tert-butyl-p-cresol is used; the rest of the contents are the same as those in Preparation Example 7.

[0066] Preparation Example 9

[0067] A liquid hydrogen storage material, which differs from Preparation Example 7 in that: 2,6-di-tert-butyl-p-cresol is not added, and the tetraisopropyl titanate content is 300g; the rest of the contents are the same as those in Preparation Example 7.

[0068] Preparation Example 10

[0069] A liquid hydrogen storage material, which differs from Preparation Example 7 in that: N-propylcarbazole is used in place of N-isopropylindole by mass, and N-propylcarbazole is used in place of N-isopropylcarbazole by mass; the rest is the same as Preparation Example 7.

[0070] Preparation Example 11

[0071] A liquid hydrogen storage material, which differs from Preparation Example 7 in that N-propylcarbazole is used in place of N-isopropylindole by mass; the rest is the same as Preparation Example 7.

[0072] Preparation Example 12

[0073] A liquid hydrogen storage material differs from Preparation Example 7 in that N-propylcarbazole is used in place of N-isopropylindole by mass, and N-propylindole is used in place of N-isopropylcarbazole by mass; the rest is the same as Preparation Example 7.

[0074] Preparation Example 13

[0075] A liquid hydrogen storage material, which differs from Preparation Example 7 in that: 150g of tetraisopropyl titanate and 150g of 2,6-di-tert-butyl-p-cresol are used; the rest of the contents are the same as those in Preparation Example 7.

[0076] Preparation Example 14

[0077] A liquid hydrogen storage material, which differs from Preparation Example 7 in that: tetraisopropyl titanate is 75g, 2,6-di-tert-butyl-p-cresol is 225g; the rest is the same as Preparation Example 7.

[0078] Preparation Example 15

[0079] A liquid hydrogen storage material, which differs from Preparation Example 7 in that: tetraisopropyl titanate is 175g, 2,6-di-tert-butyl-p-cresol is 125g; the rest is the same as Preparation Example 7.

[0080] Preparation Example 16

[0081] A liquid hydrogen storage material, which differs from Preparation Example 7 in that: 50g of tetraisopropyl titanate and 250g of 2,6-di-tert-butyl-p-cresol are used; the rest of the contents are the same as those in Preparation Example 7.

[0082] Preparation Example 17

[0083] A liquid hydrogen storage material, which differs from Preparation Example 7 in that: no nano-cerium oxide is added; the rest is the same as Preparation Example 7.

[0084] Preparation Example 18

[0085] A liquid hydrogen storage material differs from Preparation Example 7 in that: N-isopropylindole is 30 kg, N-isopropylcarbazole is 40 kg, 2,6-di-tert-butyl-p-cresol is 66.6 g, tetraisopropyl titanate is 33.3 g, and nano-cerium oxide is 100 g; the rest is the same as Preparation Example 7.

[0086] Preparation Example 19

[0087] A liquid hydrogen storage material differs from Preparation Example 7 in that: N-isopropylindole is 60 kg, N-isopropylcarbazole is 70 kg, 2,6-di-tert-butyl-p-cresol is 333.3 g, tetraisopropyl titanate is 166.6 g, and nano-cerium oxide is 500 g; the rest is the same as Preparation Example 7.

[0088] Example 1

[0089] A hydrogen storage process for a liquid hydrogen storage material includes the following steps:

[0090] 10 kg of liquid hydrogen storage material was subjected to argon gas at 100 °C and a vacuum of -0.095 MPa for 25 min at an argon gas flow rate of 50 sccm to obtain pretreated liquid hydrogen storage material. The liquid hydrogen storage material was derived from preparation example 7.

[0091] 80g of Ru / N-CNT catalyst, derived from Preparation Example 1, was packed into the isothermal section of a trickle bed reactor. High-purity hydrogen (≥99.99% purity) was compressed to 75 bar using a compressor. Pretreated liquid hydrogen storage material was pumped through a high-pressure feed pump and mixed with the 80 bar hydrogen in a mixer. The mixture was then introduced into the trickle bed reactor. The volume ratio of hydrogen to pretreated liquid hydrogen storage material was 300:1. The pressure was set at 80 bar, the temperature at 150°C, and the liquid hourly space velocity (LISH) at 1 h⁻¹. -1 The hydrogen storage liquid was obtained.

[0092] Comparative Example 1

[0093] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 8; the rest is the same as in Example 1.

[0094] Comparative Example 2

[0095] A hydrogen storage process for a liquid hydrogen storage material, which differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 9; the rest is the same as Example 1.

[0096] Example 2

[0097] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 10; the rest is the same as in Example 1.

[0098] Example 3

[0099] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 11; the rest is the same as in Example 1.

[0100] Example 4

[0101] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 12; the rest is the same as in Example 1.

[0102] Example 5

[0103] A hydrogen storage process for a liquid hydrogen storage material, which differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 13; the rest is the same as Example 1.

[0104] Example 6

[0105] A hydrogen storage process for a liquid hydrogen storage material, which differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 14; the rest is the same as Example 1.

[0106] Example 7

[0107] A hydrogen storage process for a liquid hydrogen storage material, which differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 15; the rest is the same as Example 1.

[0108] Example 8

[0109] A hydrogen storage process for a liquid hydrogen storage material, which differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 16; the rest is the same as Example 1.

[0110] Example 9

[0111] A hydrogen storage process for a liquid hydrogen storage material, which differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 17; the rest is the same as Example 1.

[0112] Example 10

[0113] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that: an equal volume of Ru / C catalyst is used instead of the Ru / N-CNT catalyst, and the Ru / C catalyst is purchased from Xi'an Kaili New Material Co., Ltd.; the rest is the same as in Example 1.

[0114] Example 11

[0115] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that: the Ru / N-CNT catalyst is 50g; the rest is the same as in Example 1.

[0116] Example 12

[0117] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that: the Ru / N-CNT catalyst is 100g; the rest is the same as in Example 1.

[0118] Example 13

[0119] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that: the Ru / N-CNT catalyst is 40g; the rest is the same as in Example 1.

[0120] Example 14

[0121] A hydrogen storage process for a liquid hydrogen storage material, which differs from Example 1 in that: the Ru / N-CNT catalyst is 120g; the rest is the same as in Example 1.

[0122] Example 15

[0123] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that the Ru / N-CNT catalyst is derived from Preparation Example 2; the rest is the same as in Example 1.

[0124] Example 16

[0125] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that the Ru / N-CNT catalyst is derived from Preparation Example 3; the rest is the same as in Example 1.

[0126] Example 17

[0127] A hydrogen storage process for a liquid hydrogen storage material, which differs from Example 1 in that the Ru / N-CNT catalyst is derived from Preparation Example 4; the rest is the same as in Example 1.

[0128] Example 18

[0129] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that the Ru / N-CNT catalyst is derived from Preparation Example 5; the rest is the same as in Example 1.

[0130] Example 19

[0131] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that the Ru / N-CNT catalyst is derived from Preparation Example 6; the rest is the same as in Example 1.

[0132] Example 20

[0133] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 18, the hydrogen is pressurized to 70 bar, and the temperature is set to 130°C; the rest is the same as in Example 1.

[0134] Example 21

[0135] A hydrogen storage process for a liquid hydrogen storage material differs from Example 1 in that the liquid hydrogen storage material is derived from Preparation Example 19, the hydrogen is pressurized to 80 bar, and the temperature is set to 160°C; the rest is the same as in Example 1.

[0136] The following tests were conducted on Examples 1-21 and Comparative Examples 1-2:

[0137] Weigh the liquid hydrogen storage material before and after the reaction. m_before: the mass of the liquid hydrogen storage material before the reaction, m_after: the mass of the liquid hydrogen storage material after the reaction. The hydrogen storage density is (m_after - m_before) / m_after × 100%. The test results are shown in Table 1.

[0138] Table 1. Detection results of Examples 1-21 and Comparative Examples 1-2

[0139]

[0140] Based on Table 1, the test results are analyzed as follows:

[0141] Comparing Example 1 and Comparative Examples 1-2, the hydrogen storage density of Example 1 is greater than that of Comparative Examples 1-2. The difference between Example 1 and Comparative Examples 1-2 is that 2,6-di-tert-butyl-p-cresol and tetraisopropyl titanate were added to the liquid hydrogen storage materials in Example 1. As a Lewis acid precursor, tetraisopropyl titanate catalyzes the activation of CH bonds through weak interactions with nitrogen-containing heterocycles, promoting hydrogenation and stabilizing intermediates, and inhibiting excessive reactions. The antioxidant 2,6-di-tert-butyl-p-cresol can quench free radical chains and reduce side reactions. Both enhance the stability and performance of the hydrogen storage materials from the perspectives of reaction pathway and free radical termination, respectively. It can be seen that the addition of 2,6-di-tert-butyl-p-cresol and tetraisopropyl titanate to the liquid hydrogen storage materials is beneficial to improving the hydrogen storage effect.

[0142] Comparing Examples 1 and 5-8, the hydrogen storage density of Example 1 is greater than that of Examples 5-8, and the hydrogen storage density of Example 5-6 is greater than that of Examples 7-8. The difference between Examples 1 and 5-8 is that the mass ratio of tetraisopropyl titanate and 2,6-di-tert-butyl-p-cresol in the liquid hydrogen storage materials of Examples 1 and 5-6 is 1:(1-3). Within this dosage range, 2,6-di-tert-butyl-p-cresol can effectively quench free radicals in the system. At the same time, tetraisopropyl titanate can regulate the reaction pathway, inhibit deep side reactions, and reduce the adverse effects that may be caused by the introduction of metal ions. It can be seen that a mass ratio of tetraisopropyl titanate and 2,6-di-tert-butyl-p-cresol of 1:(1-3) is beneficial to improving the hydrogen storage effect.

[0143] Comparing Examples 1 and 9, the hydrogen storage density of Example 1 is greater than that of Example 9. The difference between Example 1 and Example 9 is that nano-cerium oxide was added to the liquid hydrogen storage material in Example 1. The surface of nano-cerium oxide has abundant oxygen vacancies, and Ce ions exhibit a reversible +3 / +4 valence state. During hydrogen storage, oxygen vacancies can adsorb and activate hydrogen species as active sites, promoting the hydrogen overflow effect and improving the efficiency of hydrogenation reaction. Furthermore, its excellent oxygen storage and release capacity and free radical scavenging effect further enhance the cycle stability of the hydrogen storage material. It can be seen that the addition of nano-cerium oxide to the liquid hydrogen storage material is beneficial to improving the hydrogen storage effect.

[0144] Comparing Example 1 and Example 10, the hydrogen storage density of Example 1 is greater than that of Example 10. The difference between Example 1 and Example 10 is that the catalyst used for hydrogen storage in Example 1 is a Ru / N-CNT catalyst. Ruthenium efficiently activates hydrogen molecules with its d electron orbitals, while nitrogen-doped carbon nanotubes effectively anchor and disperse ruthenium particles with their high specific surface area and nitrogen defect sites, preventing their aggregation. Under the synergistic effect of the two, hydrogen dissociates on the ruthenium surface and migrates to the support surface through the hydrogen spillover effect, improving the activation and transfer efficiency of hydrogen. It can be seen that using a Ru / N-CNT catalyst for hydrogen storage is beneficial to improving the hydrogen storage effect.

[0145] Comparing Examples 1 and 11-14, the hydrogen storage density of Example 1 is greater than that of Examples 11-14, and the hydrogen storage density of Examples 11-12 is greater than that of Examples 13-14. The difference between Examples 1 and 11-14 is that the mass ratio of Ru / N-CNT catalyst to liquid hydrogen storage material used in Examples 1 and 11-12 is (0.5-1):100. It can be seen that a mass ratio of Ru / N-CNT catalyst to liquid hydrogen storage material of (0.5-1):100 is beneficial to improving the hydrogen storage effect.

[0146] Comparing Examples 1 and 15-18, the hydrogen storage density of Example 1 is greater than that of Examples 15-18, and the hydrogen storage density of Examples 15-16 is greater than that of Examples 17-18. The difference between Examples 1 and 15-18 is that the Ru loading of the Ru / N-CNT catalyst used for hydrogen storage in Example 1 is 1-6 wt%. At this ratio, the catalyst can provide sufficient active sites to fully cover the hydrogenatable sites in the liquid hydrogen storage material, enabling the hydrogenation reaction to proceed rapidly. This helps to reduce the insufficient active sites and limited reaction rate caused by too low a ratio, while also reducing the problems of local catalyst agglomeration and reduced effective surface area caused by too high a ratio. It can be seen that a Ru loading of 1-6 wt% for the Ru / N-CNT catalyst used for hydrogen storage is beneficial to improving the hydrogen storage effect.

[0147] Comparing Example 1 and Example 19, the hydrogen storage density of Example 1 is greater than that of Example 19. The difference between Example 1 and Example 19 is that the Ru precursor used in the preparation of the Ru / N-CNT catalyst for hydrogen storage in Example 1 is ruthenium acetylacetonate. As a precursor, ruthenium acetylacetonate can achieve the slow-release reduction of ruthenium ions during pyrolysis, effectively inhibiting particle aggregation and forming uniform and highly dispersed metallic ruthenium nanoparticles. The amorphous carbon layer generated by ligand decomposition not only enhances the anchoring effect of particles on nitrogen-doped carbon nanotubes, but also reduces the introduction of impurities. It can be seen that using ruthenium acetylacetonate as the Ru precursor in the preparation of the Ru / N-CNT catalyst for hydrogen storage is beneficial to improving the hydrogen storage effect.

[0148] 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 protection claimed in this application.

Claims

1. A liquid hydrogen storage material, characterized in that, The components include the following parts by weight: 30-60 portions of component A 40-70 parts of component B Stabilizing agent 0.1-0.5 parts, The stabilizing agents include tetraisopropyl titanate and 2,6-di-tert-butyl-p-cresol. Wherein, the combination of component A and component B is any of the following: (a) Component A is N-isopropylindole, and component B is N-isopropylcarbazole; (b) Component A is N-propylindole, and component B is N-propylcarbazole; (c) Component A is N-isopropylindole, and component B is N-propylindole; (d) Component A is N-propylcarbazole, and component B is N-isopropylcarbazole.

2. The liquid hydrogen storage material according to claim 1, characterized in that, The mass ratio of tetraisopropyl titanate and 2,6-di-tert-butyl-p-cresol is 1:(1-3).

3. The liquid hydrogen storage material according to claim 1, characterized in that, Also added is 0.1-0.5 parts of nano-cerium oxide.

4. A hydrogen storage process, characterized in that, Includes the following steps: Hydrogen gas is pressurized to 70-80 bar and subjected to a hydrogenation reaction with the liquid hydrogen storage material described in any one of claims 1-3 using a noble metal hydrogenation catalyst at a temperature of 130-160°C to obtain a hydrogen storage liquid.

5. A hydrogen storage process according to claim 4, characterized in that, The noble metal hydrogenation catalyst is a Ru / N-CNT catalyst.

6. A hydrogen storage process according to claim 5, characterized in that, The mass ratio of the Ru / N-CNT catalyst to the liquid hydrogen storage material is (0.5-1):

100.

7. A hydrogen storage process according to claim 5, characterized in that, The Ru / N-CNT catalyst has a Ru loading of 1-6 wt%.

8. A hydrogen storage process according to claim 5, characterized in that, The Ru precursor used in the preparation of the Ru / N-CNT catalyst is ruthenium acetylacetonate.

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