Ru-ni bimetallic catalyst for selective hydrogenation of quinoline organic hydrogen storage carrier, and preparation method therefor and use thereof

Abstract

The present invention relates to a Ru-Ni bimetallic catalyst for the selective hydrogenation of a quinoline organic hydrogen storage carrier, and a preparation method therefor and the use thereof. In the catalyst, carbon nitride is used as a carrier, and metal nanoparticles Ru and Ni serve as active components and are jointly loaded on the carbon nitride carrier; and the carbon nitride is prepared by mixing carbon tetrachloride, ethidene diamine and nano-silica, reacting same to obtain a carbon nitride polymer, then calcining same at 750-850ºC, performing a desilicification treatment, and then filtering and drying same. The catalyst provided in the present application has good catalytic hydrogenation performance in the selective hydrogenation of the quinoline organic hydrogen storage carrier and can achieve the omission of a solvent in a reaction system; the reaction is simple, green and environmentally friendly, and the gravimetric hydrogen storage density of the system can be maximally ensured when a quinoline compound is used as an organic hydrogen carrier; moreover, the catalyst also has a good cycling stability.

Description

Ru-Ni bimetallic catalysts for selective hydrogenation of quinoline-based organic hydrogen storage supports, their preparation methods and applications Technical Field

[0001] This application relates to the field of catalyst technology, such as a Ru-Ni bimetallic catalyst for selective hydrogenation of quinoline-based organic hydrogen storage supports, its preparation method, and its application. Background Technology

[0002] Hydrogen energy is playing an increasingly important role in the development of sustainable energy. It is a clean energy carrier that can be produced from renewable energy sources and used in various sectors such as transportation, industry, and power generation. Hydrogen storage is a key issue in the development of the hydrogen economy, and one of the most promising hydrogen storage and transportation technologies is the use of organic hydrogen storage carriers. Organic hydrogen storage technology is based on the chemical binding, transport, storage, and subsequent extraction of H2 at the point of use within organic molecules (such as aromatic compounds and N-heterocyclic rings).

[0003] Despite the promising application potential of organic hydrogen storage technology, it faces several scientific bottlenecks, including the need for highly efficient and durable catalysts, optimization of hydrogen storage capacity, and the kinetics of the hydrogenation process. Therefore, developing hydrogenation catalysts with high catalytic activity, high selectivity, low cost, and good catalytic stability is crucial for the commercial application of N-heterocyclic organic hydrogen storage supports.

[0004] Quinoline is an N-heterocyclic organic hydrogen storage carrier with an adjustable hydrogen storage density ranging from 3% to 7.19%, and its physicochemical properties are similar to those of petroleum. Its fully hydrogenated product (DHQ) has a hydrogen storage capacity of 7.19 wt.%, while the semi-hydrogenated product 1,2,3,4-tetrahydroquinoline (Py-THQ) has a hydrogen storage capacity of 3.0 wt.%, making it a very promising hydrogen storage carrier.

[0005] Currently reported catalysts for hydrogenation of quinoline-based organic hydrogen storage supports cannot simultaneously achieve high catalytic activity and high selectivity. More importantly, the presence of highly coordinating intermediates in the hydrogenation process of quinoline compounds significantly reduces the catalyst's cycle life, severely impacting its lifespan. Therefore, providing a catalyst system with high catalytic activity, high selectivity, and long cycle life has become an urgent technical problem to be solved. Summary of the Invention

[0006] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0007] This application provides a Ru-Ni bimetallic catalyst for the selective hydrogenation of quinoline-based organic hydrogen storage supports, its preparation method, and its application. The catalyst provided in this application exhibits excellent catalytic hydrogenation performance in the selective hydrogenation of quinoline-based organic hydrogen storage supports. It eliminates the need for a solvent in the reaction system, making the reaction simple, environmentally friendly, and maximizing the mass hydrogen storage density of the system when using quinoline compounds as organic hydrogen supports. Furthermore, the catalyst demonstrates excellent cycle stability, meeting the requirements for the commercial application of N-heterocyclic organic hydrogen storage supports.

[0008] In the first aspect, this application provides a Ru-Ni bimetallic catalyst for selective hydrogenation of quinoline-based organic hydrogen storage supports. The Ru-Ni bimetallic catalyst uses carbon nitride as a support, and metal nanoparticles Ru and Ni are co-loaded on the carbon nitride support as active components in a mass ratio of 5:(1.5-2.5).

[0009] The carbon nitride is prepared by a method comprising the following steps:

[0010] (1) Carbon tetrachloride, ethylenediamine and nano-silica with a particle size of 25-40 nm are mixed and reacted to obtain a polymer of carbon nitride;

[0011] (2) The polymer of carbon nitride obtained in step (1) is calcined at 750-850℃, desiliconized, filtered and dried to obtain carbon nitride carrier.

[0012] The Ru-Ni bimetallic catalyst provided in this application is used for the selective hydrogenation of quinoline-based organic hydrogen storage supports. Specifically, it can be used for the half-hydrogenation of quinoline-based organic hydrogen storage supports to generate the half-hydrogenation product 1,2,3,4-tetrahydroquinoline (Py-THQ), and it can also be used for the full hydrogenation of quinoline-based organic hydrogen storage supports to generate decahydroquinoline (DHQ).

[0013] The Ru-Ni bimetallic catalyst provided in this application, when used for the selective hydrogenation of quinoline-based organic hydrogen storage supports, completely eliminates the need for adding solvents to the reaction system. That is, the Ru-Ni bimetallic catalyst provided in this application can achieve selective hydrogenation of quinoline-based organic hydrogen storage supports in a reaction system without adding any solvents or additives. Furthermore, it can ensure a conversion rate of over 95% at lower temperatures and in a shorter time, with selectivity of both the semi-hydrogenation and full-hydrogenation products exceeding 95%. Simultaneously, the Ru-Ni bimetallic catalyst provided in this application also exhibits excellent cycling stability; even after more than 6 cycles, it can still guarantee a hydrogenation conversion rate of quinoline compounds and a selectivity of over 95% for the corresponding semi-hydrogenation and full-hydrogenation products.

[0014] Therefore, when using the Ru-Ni bimetallic catalyst provided in this application for the selective hydrogenation of quinoline-based organic hydrogen storage supports, it has the following advantages:

[0015] Firstly, in the selective hydrogenation reaction system of quinoline-based organic hydrogen storage carriers, the addition of any form of solvent can be omitted. Omitting the solvent simplifies the reaction and makes it more environmentally friendly. More importantly, using a solvent-free system maximizes the mass hydrogen storage density of the system when using quinoline-based compounds as organic hydrogen carriers, which is more conducive to the commercial application of organic hydrogen storage materials.

[0016] For example, using 1g of quinoline as the reaction substrate, when 1g of solvent is added to the system, the decahydroquinoline is obtained through a complete hydrogenation reaction. The molecular weight of the decahydroquinoline is 139, and the molecular weight of the added hydrogen atoms is 10. The formula for calculating the mass hydrogen storage density of this system is: 10 / 139 / (1g+1g)=0.036. However, in the solvent-free system provided in this application, the mass hydrogen storage density is adjusted to: 10 / 139 / 1g=0.0719, which is at least double that of the solvent-containing system, thereby maximizing the mass hydrogen storage density of the system when quinoline compounds are used as organic hydrogen carriers.

[0017] Secondly, although the addition of solvent is omitted in this application, the conversion rate and product selectivity are not reduced accordingly. Moreover, surprisingly, while ensuring that the conversion rate and product selectivity are both above 95%, the temperature of the half-hydrogenation reaction is reduced to below 40°C and the temperature of the full-hydrogenation reaction is reduced to below 100°C. The reaction time is also greatly shortened, thereby significantly saving reaction time and energy consumption.

[0018] Thirdly, the Ru-Ni bimetallic catalyst provided in this application not only ensures high catalytic activity and high selectivity during the first use, but also exhibits excellent stability during catalyst recycling. Even when recycled to the sixth use, the conversion rate of hydrogenation of quinoline compounds and the selectivity of the corresponding products can still be above 95% using the corresponding catalyst, thereby greatly saving catalyst costs and making the reaction system simpler and more efficient.

[0019] The Ru-Ni bimetallic catalyst provided in this application uses carbon nitride prepared by a specific process as a support. Through the combination of Ru and Ni as active components and the use of a specific carbon nitride support, a synergistic catalyst system is formed, which together achieves high conversion rate, high selectivity and high cycle stability of the corresponding products during selective hydrogenation of quinoline-based organic hydrogen storage supports. Furthermore, the reaction system does not require the addition of solvents, and the reaction temperature is lower and the reaction time is shorter.

[0020] In this application, when using the Ru-Ni bimetallic catalyst for the semi-hydrogenation or full-hydrogenation catalysis of quinoline compounds, under the same pressure as currently common reactions, this application can reduce the temperature of the semi-hydrogenation reaction to below 40°C and the temperature of the full-hydrogenation reaction to below 100°C, and can achieve a conversion rate of over 95% in a shorter time, so that the selectivity of the semi-hydrogenation product 1,2,3,4-tetrahydroquinoline and the full-hydrogenation product (DHQ) is both over 95%.

[0021] Taking quinoline as an example, using the Ru-Ni bimetallic catalyst provided in this application, at a reaction pressure of 3 MPa and a reaction temperature of 40°C, a conversion rate of over 95% can be achieved in just 4 hours, with a selectivity of over 98% for the semi-hydrogenated product 1,2,3,4-tetrahydroquinoline. Maintaining a pressure of 3 MPa and controlling the reaction temperature at 100°C, a conversion rate of over 99% can also be achieved in just 4 hours, with a selectivity of over 95% for the fully hydrogenated product.

[0022] In the Ru-Ni bimetallic catalyst provided in this application, the mass ratio of metal nanoparticles Ru to Ni is 5:(1.5-2.5), for example, it can be 5:1.5, 5:1.67, 5:1.8, 5:2, 5:2.2 or 5:2.5, and can be selected as 5:(1.8-2.2).

[0023] This application controls the mass ratio of Ru to Ni in metal nanoparticles to be 5:(1.5-2.5), which enables the catalyst to exhibit excellent catalytic activity and high selectivity, while also ensuring high conversion and high selectivity for the hydrogenation of quinoline compounds even after more than 6 cycles of catalyst recycling, further extending the catalyst's service life. When Ru or Ni is used alone, it is impossible to simultaneously guarantee high catalyst activity and cycle stability; the combination of Ru and Ni produces a synergistic effect. Furthermore, even when using a combination of Ru and Ni, if their mass ratio is not within the range of 5:(1.5-2.5), whether reducing Ru and increasing Ni, or increasing Ru and reducing Ni, it is impossible to simultaneously guarantee high catalyst activity, high conversion rates in both half-hydrogenation and full-hydrogenation catalysis, and high selectivity of the corresponding products, leading to poorer cycle stability of the catalyst.

[0024] This application uses a specific carbon nitride as a support. When carbon nitride is replaced with a common carbon support, such as activated carbon, the conversion rate during half-hydrogenation will be greatly reduced and the selectivity of the product during full-hydrogenation will decrease. Carbon as a support cannot simultaneously achieve a conversion rate of more than 95% and a selectivity of more than 95% for the corresponding products during both half-hydrogenation and full-hydrogenation.

[0025] Furthermore, the carbon nitride (CN) support in this application is prepared by a specific method. In particular, by using nano-silica as a template agent and controlling its particle size, the specific surface area of ​​the sample can be adjusted, the pore structure and the regular mesopore distribution can be controlled, thereby giving it a higher metal dispersion ability.

[0026] This application achieves this by controlling the particle size of nano-silica to 25-40 nm (e.g., 25 nm, 26 nm, 28 nm, 30 nm, 35 nm, 38 nm, or 40 nm). This provides a more suitable pore structure, allowing for sufficient metal loading and improving metal utilization. However, when the particle size of nano-silica is less than 25 nm (e.g., 15 nm), the pore size of the support inevitably collapses, making it difficult for metal to enter the support and thus affecting the loading capacity. When the particle size of nano-silica is greater than 40 nm (e.g., 50 nm), the pores of the support are too large, which may lead to metal loss after several cycles, hindering the reuse of the catalyst.

[0027] In preparing the carbon nitride support, this application uses a raw material system composed of carbon tetrachloride, ethylenediamine, and nano-silica. After mixing and reacting the raw materials, a polymer of carbon nitride is obtained, which is then calcined at a temperature of 750-850℃ (e.g., 750℃, 780℃, 800℃, 810℃, 820℃, or 850℃). By using a calcination temperature within this range, the carbon nitride can achieve an appropriate degree of graphitization. However, when the calcination temperature is too high (e.g., 900℃), the degree of graphitization of the carbon nitride is too high, and the loading capacity of the support deteriorates. Conversely, when the calcination temperature is too low (e.g., 700℃), the proportions of pyridine nitrogen, pyrrole nitrogen, and graphitic nitrogen become unbalanced, thus failing to exert the synergistic effect of these three nitrogens and reducing the loading capacity of the active components.

[0028] The carbon nitride support obtained by the preparation method provided in this application has an ordered mesoporous structure and the advantage of stable properties. When metal nanoparticles Ru and Ni are co-loaded on the carbon nitride support as active components, its special pore structure allows the metal nanoparticles to be highly dispersed, and the reaction molecules can reside in the pores for a long time, thus ensuring that the reaction can proceed fully. Furthermore, since the nitrogen doping process can introduce defect sites and nitrogen species, it improves the physicochemical properties of the catalyst and can interact with active species to enhance catalytic performance, thereby enabling better selective hydrogenation of quinoline-based organic hydrogen storage supports.

[0029] In one embodiment, the calcination temperature in step (2) is 780-820°C.

[0030] This application further regulates the calcination temperature to 780-820℃, which allows for better synergistic effects of the three types of nitrogen: pyridine nitrogen, pyrrole nitrogen, and graphitic nitrogen, thus making it more conducive to the selective hydrogenation of quinoline compounds.

[0031] In one embodiment, in the Ru-Ni bimetallic catalyst provided in this application, the particle sizes of the metal nanoparticles Ru and Ni are each independently 3-4.5 nm, for example, 3 nm, 3.5 nm, 4 nm or 4.5 nm.

[0032] In one embodiment, with the mass of the carbon nitride support being 100%, the total mass percentage of the metal nanoparticles Ru and Ni is 5-7%, for example, it can be 5%, 5.5%, 6%, 6.5% or 7%; the mass ratio of the metal nanoparticles Ru to Ni is 5:(1.5-2.5). For example, the mass percentage of the metal nanoparticles Ru can be 5%, and the mass percentage of the metal nanoparticles Ni can be 2%, etc.

[0033] Secondly, this application provides a method for preparing a Ru-Ni bimetallic catalyst for selective hydrogenation of quinoline-based organic hydrogen storage supports as described in the first aspect, the preparation method comprising the following steps:

[0034] (1) Carbon tetrachloride, ethylenediamine and nano-silica with a particle size of 25-40 nm are mixed and reacted to obtain a polymer of carbon nitride;

[0035] (2) The carbon nitride polymer obtained in step (1) is calcined at 750-850℃, desiliconized, filtered and dried to obtain carbon nitride carrier;

[0036] (3) Dissolve the carbon nitride support obtained in step (2) in water, and add a mixture containing Ru to the mixture. 3+ and Ni 2+ An unreduced Ru-Ni bimetallic catalyst was obtained by ultrasonic impregnation and vacuum drying of a salt solution.

[0037] (4) Reduce the unreduced Ru-Ni bimetallic catalyst obtained in step (3) and raise the temperature, then lower it to room temperature and introduce a protective gas to obtain the Ru-Ni bimetallic catalyst.

[0038] The particle size of the nano-silica described in step (1) of this application is 25-40nm, for example, it can be 25nm, 26nm, 28nm, 30nm, 35nm, 38nm or 40nm, etc.

[0039] The calcination temperature described in step (2) of this application is 750-850℃, for example, it can be 750℃, 780℃, 800℃, 810℃, 820℃ or 850℃, etc., and can be selected as 780-820℃.

[0040] In this application, when the Ru-Ni bimetallic catalyst prepared by the corresponding preparation method is used for the semi-hydrogenation reaction of quinoline-based organic hydrogen storage carrier, it can improve the selectivity of the semi-hydrogenation product 1,2,3,4-tetrahydroquinoline (Py-THQ) to more than 98% at a temperature as low as 40°C, while ensuring a conversion rate of more than 95%.

[0041] When the corresponding Ru-Ni bimetallic catalyst is used for the full hydrogenation reaction of quinoline-based organic hydrogen storage carriers, it can ensure that the selectivity of the full hydrogenation product is above 95% and the conversion rate of the full hydrogenation product can reach above 99% even at temperatures as low as 100°C.

[0042] In other words, the Ru-Ni bimetallic catalyst provided in this application can guarantee a conversion rate of over 95% and a selectivity of over 95% for the corresponding products in both the half-hydrogenation and full-hydrogenation reactions of quinoline-based organic hydrogen storage supports, demonstrating the high catalytic activity of the catalyst in both half-hydrogenation and full-hydrogenation reactions.

[0043] In one embodiment, the mass ratio of carbon tetrachloride, ethylenediamine and nano-silica in step (1) is (5-10):(2-4):1, where “(5-10)” can be 5, 7, 8, 10, etc.; and “(2-4)” can be 2, 3, 4, etc.

[0044] In one embodiment, the calcination in step (2) is carried out in a tubular furnace; the tubular furnace is heated to 750-850°C at a rate of 2-4°C / min (e.g., 2°C / min, 2.5°C / min, 3°C / min, 4°C / min) and held for 3-5 hours (3 hours, 4 hours, 5 hours), and a protective gas (e.g., nitrogen) at a rate of 100-200 mL / min (e.g., 100 mL / min, 150 mL / min, 200 mL / min) is introduced into the calcination environment.

[0045] In one implementation, the Ru added in step (3) 3+ The salt is RuCl3, and Ni is added. 2+ The salt is Ni(OAc)2, but other types of ruthenium or nickel salts can also be added. For Ru 3+ Salt and Ni 2+ The amount of salt added is sufficient to ensure that the mass ratio of Ru to Ni in the final catalyst is 5:(1.5-2.5).

[0046] In one embodiment, the ultrasound time in step (3) is 5-15 min (e.g., 5 min, 10 min, 15 min); the immersion time is 4-8 h (e.g., 4 h, 5 h, 6 h, 8 h); and the immersion temperature is 40-60 °C (e.g., 40 °C, 45 °C, 50 °C, 55 °C, 60 °C).

[0047] In one embodiment, the reduction heating program in step (4) is to heat to 350-450°C (e.g., 350°C, 380°C, 400°C, 420°C, 450°C) at a rate of 1-5°C / min (e.g., 1°C / min, 2.5°C / min, 3°C / min, 5°C / min) and hold for 1-3 hours (e.g., 1 hour, 2 hours, 3 hours) while introducing a protective gas (e.g., nitrogen) at a rate of 100-200 mL / min (e.g., 100 mL / min, 150 mL / min, 200 mL / min) throughout the reduction environment.

[0048] As an optional solution, the method for preparing the Ru-Ni bimetallic catalyst for selective hydrogenation of quinoline-based organic hydrogen storage supports provided in this application may include the following steps:

[0049] (1) Carbon tetrachloride, ethylenediamine and nano silica are mixed in a mass ratio of (5-10):(2-4):1. The mixture is refluxed at 80-100℃ for 5-10 h. The solvent is then evaporated to obtain a polymer of carbon nitride, which is placed in an oven at 100-120℃ overnight.

[0050] (2) The polymer of carbon nitride obtained in step (1) is placed in a tube furnace and calcined at 750-850℃. After cooling to room temperature, the sample is taken out and crushed. It is desiliconized with acidic solution for 20-30 h, filtered, washed with water until neutral, and dried to obtain carbon nitride support.

[0051] (3) Dissolve the carbon nitride support obtained in step (2) in water, and add Ru to the mixture. 3+ and Ni 2+ The solution was subjected to sonication and impregnation in a salt solution to remove the solvent. The solution was then vacuum dried to obtain an unreduced Ru-Ni bimetallic catalyst.

[0052] (4) The unreduced Ru-Ni bimetallic catalyst obtained in step (3) is placed in a tube furnace for reduction. After the temperature drops to room temperature, nitrogen gas is introduced for protection, and finally the Ru-Ni bimetallic catalyst is obtained.

[0053] The preparation method related to the carbon nitride support provided in the second aspect of this application is also applicable to the preparation of the carbon nitride support in the first aspect of this application, and will not be described again here.

[0054] Thirdly, this application provides the application of the Ru-Ni bimetallic catalyst described in the first aspect for selective hydrogenation of quinoline-based organic hydrogen storage supports in the selective hydrogenation and storage of quinoline-based compounds.

[0055] In one embodiment, the Ru-Ni bimetallic catalyst can be used to catalyze both the half-hydrogenation and full-hydrogenation of quinoline compounds.

[0056] In this application, the Ru-Ni bimetallic catalyst is used in both the half-hydrogenation and full-hydrogenation reactions of quinoline compounds under solvent-free conditions.

[0057] This application effectively avoids the addition of solvents in related technologies. Since the conversion rate is over 95% and the product selectivity is over 95% even without solvent, this application demonstrates the high conversion rate and selectivity of the Ru-Ni bimetallic catalyst in this application. In addition, it eliminates the need for solvents in the reaction system, making the reaction simple, green and environmentally friendly. It also maximizes the mass hydrogen storage density of the system when quinoline compounds are used as organic hydrogen carriers. At the same time, the catalyst also has excellent cycle stability.

[0058] In half-hydrogenation or full-hydrogenation reactions, the Ru-Ni bimetallic catalyst provided in this application only needs to have a molar ratio of Ru to quinoline compounds of 2-3% (e.g., 2%, 2.5%, or 3%) to achieve a conversion rate of over 95% and a selectivity of over 95% for the corresponding products, demonstrating high catalytic activity and high selectivity.

[0059] The Ru-Ni bimetallic catalyst is used for the catalytic semi-hydrogenation of quinoline compounds, including:

[0060] Quinoline compounds are mixed with Ru-Ni bimetallic catalysts and reacted at 30-40℃ (e.g., 30℃, 35℃, 38℃, 40℃) to give the semi-hydrogenated product 1,2,3,4-tetrahydroquinoline.

[0061] The Ru-Ni bimetallic catalyst prepared in this application achieves a conversion rate of over 95% at 40℃ and a selectivity of over 98% for the semi-hydrogenated product Py-THQ, while the commercial Ru / C catalyst at the same temperature and time has a conversion rate of only 9.3%. This demonstrates that the Ru-Ni bimetallic catalyst used in this application has a higher conversion rate.

[0062] The Ru-Ni bimetallic catalyst is used for the catalytic complete hydrogenation of quinoline compounds, including:

[0063] Quinoline compounds are mixed with Ru-Ni bimetallic catalysts and reacted at 80-100℃ (e.g., 80℃, 85℃, 90℃, 95℃, 100℃) to obtain the fully hydrogenated product decahydroquinoline.

[0064] The Ru-Ni bimetallic catalyst prepared in this application can achieve a conversion rate of over 99% at 100℃, and the selectivity of the fully hydrogenated product DHQ can reach over 95%. In contrast, the commercial Ru / C catalyst at the same temperature and time has a selectivity of only about 35%, with the remaining 65% being the semi-hydrogenated product Py-THQ. This demonstrates that the Ru-Ni bimetallic catalyst used in this application has higher selectivity.

[0065] In this application, when selective hydrogenation of quinoline-based organic hydrogen storage carriers is carried out using the Ru-Ni bimetallic catalyst, the pressure only needs to be around 3 MPa, and the entire reaction can be carried out at a lower temperature and in a shorter time (4 h).

[0066] In this application, the Ru-Ni bimetallic catalyst can be recycled more than 6 times when used for selective hydrogenation and storage of quinoline compounds. Even after the Ru-Ni bimetallic catalyst has been recycled 6 times, the conversion rate of hydrogenation of quinoline compounds and the selectivity of the corresponding products can still reach more than 95%, which demonstrates the excellent cycle stability of the catalyst.

[0067] The quinoline compounds in this application can be quinolines, or other quinoline compounds as described below, without any special limitation.

[0068] .

[0069] For the aforementioned quinoline compounds, the Ru-Ni bimetallic catalyst provided in this application can also achieve a half-hydrogenation catalysis with a conversion rate and half-hydrogenation product selectivity of over 95% at a reaction temperature as low as 40°C; at the same time, it can also achieve a full-hydrogenation catalysis with a conversion rate and full-hydrogenation product selectivity of over 95% at a reaction temperature as low as 100°C.

[0070] Compared with related technologies, this application has at least the following beneficial effects:

[0071] (1) The Ru-Ni bimetallic catalyst prepared by this application through a simple and green method can have the metal nanoparticles Ru and Ni as active components highly dispersed on the carbon nitride support prepared by a specific process, and has a strong hydrogen binding ability. It can obtain the semi-hydrogenated product (Py-THQ) with high selectivity at 40°C and the fully hydrogenated product (DHQ) with high selectivity at 100°C. Furthermore, the introduction of Ni significantly improves the catalytic activity and stability of the Ru catalyst.

[0072] (2) The Ru-Ni bimetallic catalyst provided in this application solves the problems of low catalytic activity, slow hydrogen storage rate, high reaction temperature, high price and short service life caused by catalyst instability in existing catalysts, and well meets the requirements for commercial application of N-heterocyclic organic liquid hydrogen storage carrier (LOHC).

[0073] (3) This application allows the reaction system to omit the solvent, making the reaction simple, green and environmentally friendly, and ensuring the mass hydrogen storage density of the system to the greatest extent when quinoline compounds are used as organic hydrogen carriers.

[0074] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims. Attached Figure Description

[0075] Figure 1 is a flowchart of the preparation of Ru-Ni / CN catalyst in Example 1.

[0076] Figure 2 is a SEM image of the CN vector prepared in Example 1.

[0077] Figure 3 shows the XRD patterns of the CN support and Ru-Ni / CN catalyst prepared in Example 1.

[0078] Figure 4 is an EDS diagram of the Ru-Ni / CN catalyst of Example 1.

[0079] Figure 5 is a TEM image of the Ru-Ni / CN catalyst of Example 1.

[0080] Figure 6 shows the particle size distribution of the Ru-Ni / CN catalyst in Example 1.

[0081] Figure 7 shows the lattice stripe pattern of the Ru-Ni / CN catalyst in Example 1.

[0082] Figure 8 shows the hydrogenation curves of the Ru-Ni / CN catalyst in Example 1 for storing hydrogen to generate Py-THQ at different temperatures.

[0083] Figure 9 shows the hydrogenation curves of the Ru-Ni / CN catalyst in Example 1 for storing hydrogen to generate DHQ at different temperatures.

[0084] Figure 10 shows the changes in conversion and selectivity of the Ru-Ni / CN catalyst in Example 1 after 6 cycles.

[0085] Figure 11 shows the changes in conversion and selectivity of semi-hydrogenated Py-THQ after six cycles of the Ru-Ni / CN catalyst in Example 1.

[0086] Figure 12 shows the fine XPS spectra of Ru3P before and after the reaction of the Ru-Ni / CN catalyst in Example 1.

[0087] Figure 13 shows the NMR spectrum of the semi-hydrogenated product 1,2,3,4-tetrahydroquinoline prepared using Example 1-A.

[0088] Figure 14 shows the NMR spectrum of the fully hydrogenated product prepared using Example 1-B. Detailed Implementation

[0089] The technical solution of this application will be further described below with reference to the embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of this application that do not depart from the spirit and scope of the technical solution of this application shall be covered within the protection scope of this application.

[0090] Unless otherwise specified, all process equipment or devices used in the following embodiments are conventional equipment or devices in the art. Unless otherwise specified, all raw materials used in the embodiments of this application are commercially available. Unless otherwise specified, all technical means used in the embodiments of this application are conventional means well known to those skilled in the art.

[0091] Example 1

[0092] This embodiment provides a Ru-Ni / CN catalyst, which uses carbon nitride (CN) as a support, and metal nanoparticles Ru and Ni as active components are co-loaded on the CN support, wherein the mass ratio of Ru to Ni is 5:2.

[0093] The Ru-Ni / CN catalyst was prepared by the following method, the process of which is shown in Figure 1, including the following steps:

[0094] Step 1: Synthesis of CN vector:

[0095] Carbon tetrachloride (24 g), ethylenediamine (10.8 g), and nano-silica (30 nm, 3.2 g) were added to a 100 mL round-bottom flask. The mixture was refluxed at 90 °C for 6 h, and then the solvent was evaporated to obtain the CN polymer, which was placed in an oven at 120 °C overnight. The CN polymer was then placed in a tube furnace and heated to 800 °C at a rate of 3 °C / min and held for 5 h, with nitrogen gas at a rate of 150 mL / min introduced throughout the calcination process. After cooling to room temperature, the sample was removed and pulverized. It was desilicationed with 40 mL of HF solution (10% by mass) for 24 h, filtered, washed with pure water until neutral, and dried to obtain the CN support.

[0096] Step 2: Loading metal nanoparticles Ru and Ni onto the CN support:

[0097] Anhydrous ruthenium trichloride (RuCl3) and Ni(OAc)2 were dissolved in an appropriate amount of H2O, with the added metal Ru accounting for 5% of the mass fraction of the CN support and the added metal Ni accounting for 2% of the mass fraction of the CN support. The mixture was slowly added to a round-bottom flask containing the CN support, sonicated for 10 min, and statically mixed at 50 °C for 6 h. The solvent was evaporated using a rotary evaporator and dried in an oven at 120 °C to obtain an unreduced CN sample. Then, the CN sample to be reduced was placed in a tube furnace and heated to 400 °C in H2 (150 mL / min) at a rate of 3 °C / min and held for 2 h. After cooling to room temperature, nitrogen gas was introduced at a rate of 150 mL / min for protection. After 1 h, the Ru-Ni / CN catalyst was obtained.

[0098] Figure 2 is a SEM image of the CN support prepared in this embodiment. As can be seen from Figure 2, the pores and similar pore structures of the CN support are similar to the morphology of the cross-linked polymerization of the nano-silica template used. This shows that by using nano-silica as a template agent, porous carbon nitride with stronger metal loading capacity can be obtained, and the corresponding support structure can enhance the utilization rate of metal particles.

[0099] Figure 3 shows the XRD patterns of the CN support and Ru-Ni / CN catalyst prepared in this embodiment. As can be seen from Figure 3, only two broad peaks were observed near 24.0° and 44.1° on the CN support and the Ru-Ni / CN catalyst, which belong to the (002) and (001) planes of graphite, respectively, indicating that the CN support has low crystallinity. When the crystallinity of the catalyst support is low, its lattice structure tends to be loose, with many disordered regions and defects. These regions and defects provide abundant active sites for the catalyst, making it easier for reactant molecules to approach and adsorb onto the catalyst surface, thereby accelerating the catalytic reaction. In the Ru-Ni / CN sample, no peaks corresponding to metallic Ru (JCPDS No. 06-0663), metallic Ni (JCPDS No. 04-085), and bimetallic Ru-Ni (JCPDS No. 65-6490) were detected, indicating that there are no large-sized metal nanoparticles on the CN support surface, suggesting that Ru and Ni atoms are highly dispersed on the CN support surface.

[0100] Figure 4 shows the elemental EDS distribution of the Ru-Ni / CN catalyst in this embodiment. As can be seen from Figure 4, Ru and Ni nanoparticles are uniformly distributed on the surface of the CN support.

[0101] Figure 5 is a TEM image of the Ru-Ni / CN catalyst in this embodiment. As can be seen from Figure 5, Ru and Ni nanoparticles are highly dispersed on the CN support.

[0102] Figure 6 shows the particle size distribution of the Ru-Ni / CN catalyst in this embodiment. As can be seen from Figure 6, the average particle size of the Ru-Ni bimetallic nanoparticles is 3.9 ± 0.5 nm.

[0103] Figure 7 shows a photograph of the lattice stripes of the Ru-Ni / CN catalyst in this embodiment. Clear lattice stripes can be seen in Figure 7. The lattice spacing of the Ru-Ni / CN catalyst nanoparticles is only 0.224 nm, which well confirms that the interaction force between atoms or ions in the lattice of the catalyst is strengthened, and the synergistic effect between the metal and the support can be better exerted.

[0104] Example 2

[0105] This embodiment provides a Ru-Ni / CN catalyst, wherein the catalyst uses CN as a support, and metal nanoparticles Ru and Ni are co-loaded on the CN support as active components, wherein the mass ratio of Ru to Ni is 5:1.8.

[0106] The Ru-Ni / CN catalyst is prepared by the following method, specifically including the following steps:

[0107] Step 1: Synthesis of CN vector:

[0108] Carbon tetrachloride (20 g), ethylenediamine (8 g), and nano-silica (25 nm, 2 g) were added to a 100 mL round-bottom flask. The mixture was refluxed at 80 °C for 5 h, and then the solvent was evaporated to obtain the CN polymer. The polymer was placed in an oven at 120 °C overnight. Then, the CN polymer was placed in a tube furnace and heated to 795 °C at a rate of 3 °C / min and held for 3 h. Nitrogen gas was introduced at a rate of 100 mL / min for protection throughout the calcination process. After cooling to room temperature, the sample was removed and pulverized. The sample was desilicationed with 40 mL of HF solution (5% by mass) for 20 h, filtered, washed with pure water until neutral, and dried to obtain the CN support.

[0109] Step 2: Loading metal nanoparticles Ru and Ni onto the CN support:

[0110] Anhydrous ruthenium trichloride (RuCl3) and Ni(OAc)2 were dissolved in an appropriate amount of H2O, with the added Ru mass fraction accounting for 5% of the CN support and the added Ni mass fraction accounting for 1.8% of the CN support. The mixture was slowly added to a round-bottom flask containing the CN support, sonicated for 10 min, and statically mixed at 30 °C for 3 h. The solvent was evaporated using a rotary evaporator and dried in an oven at 100 °C to obtain an unreduced CN sample. Then, the CN sample to be reduced was placed in a tube furnace and heated to 380 °C in H2 (150 mL / min) at a rate of 5 °C / min and held for 2 h. After cooling to room temperature, nitrogen gas was introduced at a rate of 150 mL / min for protection. After 1 h, the Ru-Ni / CN catalyst was obtained.

[0111] Example 3

[0112] This embodiment provides a Ru-Ni / CN catalyst, wherein the catalyst uses CN as a support, and metal nanoparticles Ru and Ni are co-loaded on the CN support as active components, wherein the mass ratio of Ru to Ni is 5:2.2.

[0113] The Ru-Ni / CN catalyst is prepared by the following method, specifically including the following steps:

[0114] Step 1: Synthesis of CN vector:

[0115] Carbon tetrachloride (28 g), ethylenediamine (12 g), and nano-silica (30 nm, 5 g) were added to a 100 mL round-bottom flask. The mixture was refluxed at 100 °C for 8 h, and then the solvent was evaporated to obtain the CN polymer. The polymer was placed in an oven at 120 °C overnight. Then, the CN polymer was placed in a tube furnace and heated to 805 °C at a rate of 3 °C / min and held for 5 h. Nitrogen gas was introduced at a rate of 150 mL / min for protection throughout the calcination process. After cooling to room temperature, the sample was removed and pulverized. The sample was desiliconized with 40 mL of HF solution (15% by mass) for 30 h, filtered, washed with pure water until neutral, and dried to obtain the CN support.

[0116] Step 2: Loading metal nanoparticles Ru and Ni onto the CN support:

[0117] Anhydrous ruthenium trichloride (RuCl3) and Ni(OAc)2 were dissolved in an appropriate amount of H2O, such that the mass fraction of added metal Ru accounted for 5% of the CN support and the mass fraction of added metal Ni accounted for 2.2% of the CN support. The mixture was slowly added to a round-bottom flask containing the CN support, sonicated for 10 min, and statically mixed at 60 °C for 8 h. The solvent was evaporated using a rotary evaporator and dried in an oven at 140 °C to obtain an unreduced CN sample. Then, the CN sample to be reduced was placed in a tube furnace and heated to 400 °C at a rate of 5 °C / min in H2 (150 mL / min) and held for 3 h. After cooling to room temperature, nitrogen gas was introduced at a rate of 150 mL / min for protection. After 1 h, the Ru-Ni / CN catalyst was obtained.

[0118] Examples 4 to 9

[0119] Compared with Example 1, only the calcination temperature during the preparation of the CN support in step one (Examples 4 to 5), the particle size of the added nano-silica (Examples 6 to 7), and the mass ratio of Ru and Ni added during the preparation of the catalyst in step two (referring to the mass ratio of Ru and Ni in the final catalyst product) (Examples 8 to 9) were changed, as shown in Table 1. "——" indicates that the same conditions as in Example 1 were obtained, and other conditions were the same as in Example 1.

[0120]

[0121] Comparative Example 1

[0122] This comparative example provides a Ru / C catalyst, which differs from Example 1 in that the CN support is directly replaced with activated carbon, and the active component is replaced with a single Ru element. The mass ratio of Ru to C support is 7%, and other aspects are the same as in Example 1.

[0123] Comparative Example 2

[0124] This comparative example provides a Ru / CN catalyst, which differs from Example 1 only in that the active component is replaced with a single Ru element, and the mass ratio of Ru to CN support is 7%, while the rest is the same as Example 1.

[0125] Comparative Example 3

[0126] This comparative example provides a Ni / CN catalyst, which differs from Example 1 only in that the active component is replaced with a single Ni element, and the mass ratio of Ni to CN support is 7%, while the rest is the same as Example 1.

[0127] Comparative Example 4

[0128] This comparative example provides a Ru-Ni / C catalyst, which differs from Example 1 only in that the CN support is directly replaced with activated carbon, while the rest is the same as Example 1.

[0129] Comparative Example 5

[0130] This comparative example provides a Ru-Ni / CN catalyst, which differs from Example 1 only in that the preparation method of the CN support is adjusted to the following steps, while the rest is the same as Example 1.

[0131] 6.0 g of urea was calcined at 500 °C in a nitrogen atmosphere in a calcining furnace at a heating rate of 5 °C / min for 2 h; the obtained material was ground into powder and washed with water several times in sequence, and then the product was dried at 60 °C for 12 h to obtain CN carrier.

[0132] Comparative Example 6

[0133] This comparative example provides a Ru-Ni / CN catalyst, which differs from Example 1 only in that the nano-silica added in the CN support preparation is replaced with mesoporous molecular sieve SBA-15 as a template agent; otherwise, it is the same as Example 1.

[0134] Comparative Example 7

[0135] This comparative example provides a Ru-Ni / CN catalyst, which differs from Example 1 only in that the calcination temperature during CN support preparation is adjusted to 700°C, while the rest is the same as Example 1.

[0136] Comparative Example 8

[0137] This comparative example provides a Ru-Ni / CN catalyst, which differs from Example 1 only in that the calcination temperature during CN support preparation is adjusted to 900°C, while the rest is the same as Example 1.

[0138] Comparative Example 9

[0139] This comparative example provides a Ru-Ni / CN catalyst, which differs from Example 1 only in that the particle size of the nano-silica added in the CN support preparation is adjusted to 15 nm, otherwise it is the same as Example 1.

[0140] Comparative Example 10

[0141] This comparative example provides a Ru-Ni / CN catalyst, which differs from Example 1 only in that the particle size of the nano-silica added in the CN support preparation is adjusted to 50 nm, otherwise it is the same as Example 1.

[0142] Comparative Example 11

[0143] This comparative example provides a Ru-Ni / CN catalyst, which differs from Example 1 only in that the mass ratio of the active components Ru and Ni is adjusted to 5:3.3, the mass fraction of metallic Ru in the catalyst accounts for 5% of the CN support, and the mass fraction of added metallic Ni accounts for 3.3% of the CN support. Everything else is the same as in Example 1.

[0144] Comparative Example 12

[0145] This comparative example provides a Ru-Ni / CN catalyst, which differs from Example 1 only in that the mass ratio of the active components Ru and Ni is adjusted to 5:3, the mass fraction of metallic Ru in the catalyst accounts for 5% of the CN support, and the mass fraction of added metallic Ni accounts for 3% of the CN support. Everything else is the same as in Example 1.

[0146] Comparative Example 13

[0147] This comparative example provides a Ru-Ni / CN catalyst, which differs from Example 1 only in that the mass ratio of the active components Ru and Ni is adjusted to 5:1, the mass fraction of metallic Ru in the catalyst accounts for 5% of the CN support, and the mass fraction of added metallic Ni accounts for 1% of the CN support. Everything else is the same as in Example 1.

[0148] The catalysts prepared in Examples 1 to 9 and Comparative Examples 1 to 13 were used for the selective hydrogenation of quinoline.

[0149] Application Example 1-A

[0150] This application example provides a method for the catalytic half-hydrogenation of quinoline, which includes the following steps:

[0151] Quinoline was mixed with the Ru-Ni / CN catalyst prepared in Example 1, wherein the amount of Ru-Ni / CN catalyst was 2% of the molar ratio of Ru to quinoline in the catalyst. The mixture was reacted at 40°C and 3 MPa for 4 h to obtain the semi-hydrogenated product 1,2,3,4-tetrahydroquinoline with a conversion rate of 99% and a selectivity of 99%.

[0152] The reaction process is as follows:

[0153]

[0154] The characterization of the semi-hydrogenated product 1,2,3,4-tetrahydroquinoline prepared in this application example is shown in Figure 13.

[0155] Comparative Application Example 1-A

[0156] This comparative application example provides a method for the catalytic half-hydrogenation of quinoline, which includes the following steps:

[0157] Quinoline was mixed with the Ru / C catalyst prepared in Comparative Example 1, wherein the amount of Ru / C catalyst was 2% of the molar ratio of Ru to quinoline in the catalyst. The mixture was reacted at 40 °C and 3 MPa for 4 h to obtain the semi-hydrogenated product 1,2,3,4-tetrahydroquinoline with a conversion rate of 9.3%.

[0158] Based on Application Example 1-A, the reaction temperature was adjusted from 40℃ to 30℃ and 50℃, resulting in the hydrogenation curves of the Ru-Ni / CN catalyst of Example 1 at different temperatures (30℃, 40℃, and 50℃) for the generation of Py-THQ, as shown in Figure 8. Figure 8 shows that when the reaction temperature is 40℃, the conversion rate can reach 11% in 0.5 h. This demonstrates that by using the appropriate Ru-Ni / CN catalyst, this application can not only significantly improve the conversion rate but also greatly shorten the reaction time and increase the reaction efficiency. This also fully illustrates that the Ru-Ni / CN catalyst provided in this application has higher catalytic activity in the semi-hydrogenation of quinoline.

[0159] Application Examples 2-A to 9-A and Comparative Examples 2-A to 13-A

[0160] Compared to Application Example 1-A, only the catalyst in Example 1 was replaced with the catalysts prepared in Examples 2 to 9 and Comparative Examples 2 to 13. Since Comparative Example 3 contains only Ni as the active component, it was adapted to be mixed according to a molar ratio of 2% for Ni to quinoline in the catalyst when using it for semi-hydrogenation. Everything else was the same as in Application Example 1-A.

[0161] The semi-hydrogenation catalytic effects of Application Examples 1-A to 9-A and Comparative Application Examples 1-A to 13-A are shown in Table 2.

[0162]

[0163] As can be seen from Table 2:

[0164] (1) Application Examples 1-A to 9-A all achieved a conversion rate of more than 95%, and the selectivity of Py-THQ was above 98%. Among them, Application Examples 1-A to 3-A even achieved a conversion rate of more than 99%, and the selectivity of Py-THQ reached more than 99%.

[0165] (2) Comparing application examples 1-A, 4-A and 5-A with comparative application examples 7-A and 8-A, it can be seen that when the calcination temperature during the preparation of CN support is too low (700℃), the conversion rate will decrease to about 80%. When the calcination temperature is too high (900℃), the conversion rate will also decrease, and the selectivity of Py-THQ will also decrease. When the calcination temperature is controlled at 780-820℃, the conversion rate can be greater than 95%, and the selectivity of Py-THQ is above 98%.

[0166] (3) Comparing application examples 1-A, 6-A and 7-A with comparative application examples 9-A and 10-A, it can be seen that when the particle size of nano silica is too small (15nm) when preparing CN support, the conversion rate will drop to about 85%. When the particle size of nano silica is too large (50nm), the conversion rate is 94%. When the particle size of nano silica is controlled at 25-40nm, the conversion rate can be greater than 95%, and the selectivity of Py-THQ is above 98%.

[0167] (4) Comparing Application Examples 1-A, 8-A and 9-A with Comparative Application Examples 11-A to 13-A, it can be seen that when the mass ratio of Ru to Ni changes, although the elemental proportion of Ru in the reaction system remains unchanged, the conversion rate and the conversion rate of Py-THQ will be affected when the content of Ni decreases or increases, based on the catalyst provided in Example 1. For example, when a smaller amount of Ni is added in Comparative Example 13 compared to Example 1, the conversion rate will decrease to 89.2%. When the proportion of Ni is increased to more than 2.5, the conversion rate will decrease even more in the catalysts provided in Comparative Examples 11 to 12. Only when the mass ratio of Ru to Ni is controlled in a suitable range (5:(1.5-2.5)) can the conversion rate reach a level of more than 95%.

[0168] (5) Comparing Application Example 1-A with Comparative Application Examples 1-A to 6-A, when Ru element alone or Ni element alone, and when the CN support is replaced, it is impossible to achieve a conversion rate of more than 95%. This also proves that the specific combination of Ru and Ni elements in this application and their loading on the CN support obtained by the specific preparation method produce a synergistic effect and work together to achieve a conversion rate of more than 95% and make the selectivity of Py-THQ reach more than 98%.

[0169] Application Example 1-B

[0170] This application example provides a method for the catalytic complete hydrogenation of quinoline, which includes the following steps:

[0171] Quinoline was mixed with the Ru-Ni / CN catalyst prepared in Example 1, wherein the amount of Ru-Ni / CN catalyst was 2% of the molar ratio of Ru to quinoline in the catalyst. The mixture was reacted at 100°C and 3 MPa for 4 h to obtain the fully hydrogenated product decahydroquinoline with a selectivity of 99%.

[0172] The reaction process is as follows:

[0173]

[0174] The characterization of the fully hydrogenated product decahydroquinoline prepared in this application example is shown in Figure 14.

[0175] Comparative application example 1-B

[0176] This comparative application example provides a method for the catalytic complete hydrogenation of quinoline, which includes the following steps:

[0177] Quinoline was mixed with the Ru / C catalyst prepared in Comparative Example 1, wherein the amount of Ru / C catalyst was 2% of the molar ratio of Ru to quinoline in the catalyst. The mixture was reacted at 100 °C and 3 MPa for 4 h to obtain the fully hydrogenated product decahydroquinoline with a selectivity of 35.1%.

[0178] Based on Application Example 1-B, the reaction temperatures were adjusted to 80℃ and 120℃, respectively, resulting in the hydrogenation curves of the Ru-Ni / CN catalyst from Example 1 at different temperatures (80℃, 100℃, and 120℃) for the hydrogen storage to DHQ reaction, as shown in Figure 9. Figure 9 shows that when the reaction temperature is 100℃, the conversion rate exceeds 40% after 1.5 h. This demonstrates that by employing the appropriate Ru-Ni / CN catalyst, this application not only significantly improves selectivity but also shortens the reaction time and increases reaction efficiency. This also fully illustrates that the Ru-Ni / CN catalyst provided in this application exhibits higher catalytic activity and selectivity in the full hydrogenation of quinoline.

[0179] Application Examples 2-B to 9-B and Comparative Examples 2-B to 13-B

[0180] Compared to Application Example 1-B, only the catalyst in Example 1 was replaced with the catalysts prepared in Examples 2 to 9 and Comparative Examples 2 to 13. Since Comparative Example 3 contained only Ni as the active component, it was adapted to be mixed according to a molar ratio of 2% for Ni to quinoline in the catalyst when using it for full hydrogenation. Everything else was the same as in Application Example 1-B.

[0181] The full hydrogenation catalytic effects of Application Examples 1-B to 9-B and Comparative Application Examples 1-B to 13-B are shown in Table 3.

[0182]

[0183] As can be seen from Table 5:

[0184] (1) Application examples 1-B to 9-B can all achieve a conversion rate of over 99%, and the selectivity of DHQ is over 95%.

[0185] (2) Comparing application examples 1-B, 4-B and 5-B with comparative application examples 7-B and 8-B, and comparing application examples 1-B, 6-B and 7-B with comparative application examples 9-B and 10-B, it can be seen that when preparing CN support, when the calcination temperature is 780-820℃ and the particle size of nano silica is controlled at 25-40nm, the selectivity of DHQ can be maintained above 95%. However, when the calcination temperature is too high or too low, or the particle size of nano silica is too large or too small, the selectivity of DHQ will decrease.

[0186] (3) Comparing Application Example 1-B with Comparative Application Examples 2-B to 3-B, when the same CN support is used and the active component is adjusted to be either Ru or Ni alone, neither can achieve the 99% DHQ selectivity that Application Example 1-B can achieve by combining Ru and Ni. In fact, when Ni is used as the active component alone, it cannot catalyze the full hydrogenation reaction of quinoline compounds. This fully demonstrates that the combination of Ru and Ni has a synergistic effect, which jointly promotes the full hydrogenation catalytic reaction of quinoline compounds.

[0187] (4) Comparing Application Example 1-B with Comparative Application Examples 4-B to 6-B, when the same active component is used and the corresponding CN support is changed to an activated carbon support or a CN support obtained by other preparation methods, it is still impossible to achieve the DHQ selectivity of 99% achieved in Application Example 1-B. In particular, when the CN support is replaced with a carbon support, its DHQ selectivity drops significantly. This also shows that by using the CN support obtained by the corresponding preparation method in this application, the full hydrogenation catalytic reaction of quinoline compounds can be better realized, resulting in higher DHQ selectivity.

[0188] (5) Comparing Application Example 1-B with Comparative Application Examples 11-B to 13-B, although they all used a combination of Ru and Ni elements, when the Ru element content is kept constant, changing the Ni element content, increasing or decreasing the Ni element content compared to Example 1, will lead to a decrease in DHQ selectivity. On the contrary, when the mass ratio of Ru to Ni elements is in the range of 5:(1.5-2.5), it can achieve a DHQ selectivity of over 95% while ensuring a conversion rate of 99%.

[0189] In summary, as can be seen from Application Examples 1-A to 9-A and Application Examples 1-B to 9-B, the present application utilizes a combination of Ni and Ru elements, along with a CN support prepared by a specific method, resulting in a synergistic effect. When the catalyst is used in the half-hydrogenation and full-hydrogenation catalytic reactions of quinoline compounds, a conversion rate of over 95% can be achieved. Furthermore, the selectivity of the half-hydrogenation product 1,2,3,4-tetrahydroquinoline and the full-hydrogenation product decahydroquinoline both reach over 95%.

[0190] Catalyst repeatability test (taking full hydrogenation as an example)

[0191] Test Example 1

[0192] Based on Example 1, the Ni element in the catalyst was replaced with Co, Fe and Pt respectively to form Ru-Co / CN catalyst, Ru-Fe / CN catalyst and Ru-Pt / CN catalyst. Other conditions were exactly the same as in Example 1. These three catalysts were used to replace the catalyst in Application Example 1-B to form Comparative Application Example 1-B', Comparative Application Example 2-B' and Comparative Application Example 3-B'.

[0193] The catalysts used in Application Example 1-B, Comparative Application Examples 1-B to 2-B, and Comparative Application Examples 1-B' to 3-B' were reused once; during the reuse, the reaction temperature, pressure, and time remained unchanged, and the results of the total hydrogenation are shown in Table 4.

[0194]

[0195] As can be seen from Table 4:

[0196] After one cycle, the catalysts prepared in Examples 1, 1, and 2 showed significant differences in selectivity for the full hydrogenation products. Specifically, the selectivity of the Ru / C catalyst prepared in Comparative Example 1 decreased to 11.3% after one cycle, while the selectivity of the Ru / CN catalyst prepared in Comparative Example 2 decreased to 71.9%. Replacing Ni with Co, Fe, and Pt also resulted in a decrease in selectivity. However, the Ru-Ni / CN catalyst prepared in Example 1 of this application maintained a selectivity of 99% even after one cycle, demonstrating the excellent cycle life of the Ru-Ni / CN catalyst provided in this application.

[0197] The data in Table 4 also show that when only Ru is used as the active component, carbon nitride (catalyst in Comparative Example 2) exhibits better selectivity and stronger cycle stability compared to using carbon as the support (catalyst in Comparative Example 1). However, its selectivity still decreases after one cycle. In contrast, this application uses a specific combination of Ru and Ni elements, also using carbon nitride as the support. Compared to using only Ru as the active component, it demonstrates a greater advantage in cycle stability, maintaining 99% selectivity after one cycle. This fully demonstrates the synergistic relationship between Ru, Ni, and the carbon nitride support, which collectively improves the selectivity and cycle repeatability of the catalyst.

[0198] Figure 10 shows the changes in conversion and selectivity of fully hydrogenated DHQ after six cycles of the Ru-Ni / CN catalyst prepared in Example 1 of this application; Figure 11 shows the changes in conversion and selectivity of semi-hydrogenated Py-THQ after six cycles of the Ru-Ni / CN catalyst prepared in Example 1 of this application.

[0199] As can be seen from Figures 10 and 11, the high activity and high selectivity of the Ru-Ni / CN catalyst provided in this application do not change with the increase of the number of cycles. The conversion rate of quinoline hydrogenation and the selectivity of the corresponding products are maintained above 95% in 6 cycles.

[0200] Figure 12 shows the fine XPS spectra of Ru3P of the Ru-Ni / CN catalyst prepared in Example 1 of this application before and after the reaction. As can be seen from Figure 12, the area ratio of Ru0 to Run+ in the Ru-Ni / CN catalyst provided by this application is basically maintained at 3:2 before and after the reaction, which further confirms that the Ru-Ni / CN catalyst provided by this application can maintain high activity even when recycled.

[0201] Therefore, the Ru-Ni / CN catalyst provided in this application not only exhibits superior selectivity compared to the catalysts of Comparative Example 1 and Comparative Example 2 after one cycle, but also maintains a conversion rate of over 95% even after six cycles, with the selectivity of the corresponding product remaining above 95%, demonstrating the excellent cycle stability of the catalyst in this application.

[0202] In summary, the Ru-Ni / CN catalyst provided in this application can achieve a conversion rate of over 95% at lower temperatures and in a shorter time in a solvent-free system, with selectivity of over 95% for both the semi-hydrogenation and full-hydrogenation products. It also exhibits excellent cycle stability, maintaining a conversion rate and selectivity of over 95% for the hydrogenation of quinoline compounds even after more than six cycles. This effectively solves the problems of low catalytic activity, slow hydrogen storage rate, high reaction temperature, high cost, and short service life due to catalyst instability in existing catalysts, thus well meeting the commercial application requirements of N-heterocyclic organic liquid hydrogen storage carriers (LOHC).

Claims

1. A Ru-Ni bimetallic catalyst for the selective hydrogenation of quinoline-based organic hydrogen storage carriers, wherein, The Ru-Ni bimetallic catalyst uses carbon nitride as a support, with metal nanoparticles Ru and Ni as active components loaded on the carbon nitride support in a mass ratio of 5:(1.5-2.5). The carbon nitride is prepared by a method comprising the following steps: (1) Carbon tetrachloride, ethylenediamine and nano-silica with a particle size of 25-40 nm are mixed and reacted to obtain a polymer of carbon nitride; (2) The polymer of carbon nitride obtained in step (1) is calcined at 750-850℃, desiliconized, filtered and dried to obtain carbon nitride carrier.

2. The Ru-Ni bimetallic catalyst of claim 1, wherein, The particle sizes of the metal nanoparticles Ru and Ni are each independently 3-4.5 nm.

3. The Ru-Ni bimetallic catalyst according to claim 1 or 2, wherein, In the preparation of the carbon nitride, the calcination temperature in step (2) is 780-820℃.

4. A method for preparing a Ru-Ni bimetallic catalyst for selective hydrogenation of quinoline-based organic hydrogen storage supports according to any one of claims 1-3, comprising the following steps: (1) Carbon tetrachloride, ethylenediamine and nano-silica with a particle size of 25-40 nm are mixed and reacted to obtain a polymer of carbon nitride; (2) The carbon nitride polymer obtained in step (1) is calcined at 750-850℃, desiliconized, filtered and dried to obtain carbon nitride carrier; (3) The carbon nitride carrier obtained in step (2) is dissolved in water, an aqueous solution containing a salt of Ru 3+ and Ni 2+ is added to the mixed system, and after ultrasonic immersion and vacuum drying, an unreduced Ru-Ni bimetallic catalyst is obtained; (4) Reduce the unreduced Ru-Ni bimetallic catalyst obtained in step (3) and raise the temperature, then lower it to room temperature and introduce a protective gas to obtain the Ru-Ni bimetallic catalyst.

5. The production method according to claim 4, wherein The calcination temperature in step (2) is 780-820℃.

6. The production method according to claim 4 or 5, wherein The mass ratio of carbon tetrachloride, ethylenediamine and nano-silica in step (1) is (5-10):(2-4):

1.

7. The method of making according to any one of claims 4-6, wherein, The calcination described in step (2) is carried out in a tubular furnace.

8. The production method according to claim 7, wherein The heating program in the tubular furnace is as follows: heat to 750-850℃ at a rate of 2-4℃ / min and hold for 3-5 hours, while introducing 100-200mL / min of protective gas into the entire calcination environment.

9. The method of making according to any one of claims 4-8, wherein, Ru added in step (3) 3+ Salt is RuCl3, Ni added 2+ Salt is Ni(OAc)2; Optionally, the Ru 3+ salt and Ni 2+ The amount of the salt is added so that the mass ratio of the metal nanoparticles Ru and Ni in the Ru-Ni bimetallic catalyst is 5:(1.5-2.5).

10. The method of making according to any one of claims 4-9, wherein, The ultrasound time in step (3) is 5-15 min; the immersion time is 4-8 h, and the immersion temperature is 40-60℃.

11. The method of making according to any one of claims 4-10, wherein, The reduction heating procedure in step (4) is as follows: heat to 350-450℃ at 1-5℃ / min and hold for 1-5 hours, and introduce 100-200mL / min of protective gas into the entire reduction environment.

12. The application of a Ru-Ni bimetallic catalyst according to any one of claims 1-3 for selective hydrogenation of quinoline organic hydrogen storage carriers in the selective hydrogenation and storage of quinoline compounds.

13. Use according to claim 12, wherein, The Ru-Ni bimetallic catalyst is used to catalyze the partial and / or full hydrogenation of quinoline compounds; Optionally, the Ru-Ni bimetallic catalyst catalyzes the selective hydrogenation of quinoline compounds under solvent-free conditions; Optionally, in the half-hydrogenation or full-hydrogenation reaction, the molar ratio of Ru to quinoline compounds in the Ru-Ni bimetallic catalyst is 2-3%.

14. Use according to claim 13, wherein, The Ru-Ni bimetallic catalyst is used for the catalytic semi-hydrogenation of quinoline compounds, including: Quinoline compounds were mixed with a Ru-Ni bimetallic catalyst and reacted at 30-40°C to give the semi-hydrogenated product 1,2,3,4-tetrahydroquinoline. Optionally, the Ru-Ni bimetallic catalyst is used for the catalytic full hydrogenation of quinoline compounds, including: Quinoline compounds were mixed with a Ru-Ni bimetallic catalyst and reacted at 80-100℃ to obtain the fully hydrogenated product, decahydroquinoline.

15. The use according to any one of claims 12 to 14, wherein, When the Ru-Ni bimetallic catalyst is used for selective hydrogenation and storage of quinoline compounds, the catalyst can be recycled ≥6 times. Optionally, when the Ru-Ni bimetallic catalyst is recycled 6 times, the conversion rate of hydrogenation of quinoline compounds is above 95%, and the selectivity of the corresponding semi-hydrogenation or full-hydrogenation products is above 95%.

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