A reverse interfacial catalyst, a preparation method and application thereof

Abstract

The application provides a reverse interface catalyst, a preparation method and application thereof. 0 The d electrons on the surface are not coordinated, so that the carboxyl of citric acid and nickel form stable coordination bonds by immersing the slightly oxidized Ni / Al2O3 in a citric acid solution, chemical modification of the surface of the Ni / Al2O3 is realized, and the Ni surface is rich in negative carboxyl groups; the surface-modified Ni / Al2O3 is dispersed in a cerium salt solution, the negative surface-modified Ni / Al2O3 can be electrostatically adsorbed with Ce 3+ Cations produce electrostatic adsorption, the pH of the dispersion system is adjusted to alkaline, the cerium salt solution is hydrolyzed and co-precipitated to generate Ce(OH)3 and is converted into CeO2 precipitate, and further generated cerium dioxide can be uniformly deposited on the surface of the metal nickel to form a close interface, thereby obtaining the reverse interface catalyst. The catalyst is used for benzene series hydrogenation reaction at low temperature and low pressure, the conversion rate of the benzene series reaches 99.5% or more, and excellent catalytic effect is exhibited, and the catalyst has good application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic liquid hydrogen storage, and particularly relates to a reverse interface catalyst, a preparation method and application thereof. BACKGROUND

[0002] As an ideal clean energy carrier, efficient and safe storage and transportation of hydrogen energy is the key bottleneck for the large-scale development of hydrogen energy economy. Liquid organic hydrogen carrier (LOHC) technology has become a promising solution due to its significant advantage of safe storage and transportation of hydrogen gas at normal pressure and temperature using conventional liquid organic compounds. Among them, the toluene / methylcyclohexane system is widely considered as one of the most promising LOHC candidate systems due to its low toxicity, excellent cycle reversibility, and high weight hydrogen capacity of up to 6.2wt%. The core of this system is to convert toluene into methylcyclohexane through catalytic hydrogenation reaction to realize chemical storage of hydrogen, and then release hydrogen from methylcyclohexane through catalytic dehydrogenation reaction. This efficient and reversible process is crucial for building a safe and economical hydrogen energy storage and transportation network.

[0003] Currently, catalysts applied to toluene hydrogenation to methylcyclohexane can be mainly divided into two categories: noble metal catalysts and non-noble metal catalysts. However, the inherent resource scarcity of noble metals leads to high cost, which seriously restricts the economy and sustainability of its large-scale industrial LOHC hydrogen storage application. Non-noble metal catalysts, especially nickel (Ni) based catalysts, have been widely used in industrial catalytic hydrogenation fields (such as oil hydrogenation) due to their good hydrogenation activity and significant cost advantage, and are considered as a potential alternative to noble metal catalysts.

[0004] Although nickel-based catalysts have cost advantages, they have significant shortcomings when applied to toluene hydrogenation to methylcyclohexane: compared with efficient noble metal catalysts, on the one hand, nickel-based catalysts usually require more stringent reaction conditions, including higher reaction temperature and higher operating pressure. On the other hand, although traditional nickel-based catalysts can achieve efficient toluene hydrogenation under high-purity hydrogen (>99.9% H2) conditions, in industrial applications, hydrogen raw materials often contain various impurities (such as O2, CO, CO2, CH4, etc.), which can easily cause catalyst poisoning, carbon deposition or sintering, and seriously reduce activity and stability. SUMMARY

[0005] To solve the problems in the background art, the application provides a reverse interface catalyst, a preparation method and application thereof. A nickel salt solution is mixed with γ-Al2O3, and then nickel ions are adsorbed on the γ-Al2O3 by standing, followed by drying and calcination to obtain NiO / Al2O3; the NiO / Al2O3 is subjected to reduction treatment in a hydrogen atmosphere to reduce NiO to metallic nickel, thereby obtaining Ni / Al2O3; the Ni / Al2O3 is subjected to oxidation treatment and then immersed in a citric acid solution, so that the carboxyl groups in the citric acid are coordinated with nickel, and the surface-modified Ni / Al2O3 is obtained after drying; the surface-modified Ni / Al2O3 is dispersed in a cerium salt solution, the pH of the dispersion system is adjusted to alkaline, the cerium salt solution is hydrolyzed, and the generated cerium dioxide is uniformly deposited on the surface of the metallic nickel to form a close interface; and the reverse interface catalyst Ni@CeO2 / Al2O3 is obtained after drying. Through the reverse interface construction strategy, the citric acid surface modification and the controllable coprecipitation technology are used to realize the uniform deposition of CeO2 on the special structure of Ni particles, greatly increase the contact area of Ni and CeO2, form more active interface sites, and facilitate the activation and conversion in the hydrogenation reaction of benzene series.

[0006] The specific application contents are as follows:

[0007] In a first aspect, the application provides a preparation method of a reverse interface catalyst, which specifically comprises the following steps:

[0008] S1, a nickel salt solution is mixed with γ-Al2O3, and then nickel ions are adsorbed on the γ-Al2O3 by standing, followed by drying and calcination to obtain NiO / Al2O3;

[0009] S2, the NiO / Al2O3 is subjected to reduction treatment in a hydrogen atmosphere to reduce NiO to metallic nickel, thereby obtaining Ni / Al2O3; the Ni / Al2O3 is subjected to oxidation treatment and then immersed in a citric acid solution, so that the carboxyl groups in the citric acid are coordinated with nickel, and the surface-modified Ni / Al2O3 is obtained after drying;

[0010] S3, the surface-modified Ni / Al2O3 is dispersed in a cerium salt solution, the pH of the dispersion system is adjusted to alkaline, the cerium salt solution is hydrolyzed, and the generated cerium dioxide is uniformly deposited on the surface of the metallic nickel; and the reverse interface catalyst Ni@CeO2 / Al2O3 is obtained after drying.

[0011] Optionally, in step S1, the nickel salt in the nickel salt solution is selected from one or more of nickel nitrate, nickel chloride, nickel acetate and basic nickel carbonate, and / or the mass of metallic nickel in the nickel salt is 10wt%-15wt% of the γ-Al2O3.

[0012] Optionally, in step S1, the calcination temperature is 300-500°C, the temperature rising rate is 5-10°C / min, and the calcination time is 2-4h.

[0013] Optionally, in step S2, the reduction temperature is 300-500°C, and the reduction time is 2-5h.

[0014] Optionally, in step S2, the concentration of the citric acid solution is 0.1-0.5M.

[0015] Optionally, in step S3, the cerium salt in the cerium salt solution is selected from one or more of cerium nitrate, cerium chloride, cerium carbonate, and cerium oxalate; and / or the molar ratio of metallic nickel in the nickel salt solution to metallic cerium in the cerium salt solution is 4:1-1:1.

[0016] Optionally, in step S3, the surface-modified Ni / Al2O3 is dispersed in the cerium salt solution, and the pH of the dispersion system is adjusted to alkaline to hydrolyze the cerium salt solution, which comprises:

[0017] The surface-modified Ni / Al2O3 is dispersed in the cerium salt solution, and ammonia is added to adjust the pH of the dispersion system to alkaline under heating and stirring, wherein the heating temperature is 60-80°C, the stirring rate is 200-500r / min, and the pH of the dispersion system is 9-10.5.

[0018] Optionally, the Ni@CeO2 / Al2O3 precursor is obtained by drying, mixed with graphite, and compression-molded to obtain the reverse interface catalyst Ni@CeO2 / Al2O3.

[0019] The addition amount of the graphite is 3-8wt% of the precursor.

[0020] In a second aspect, the application provides a reverse interface catalyst, which is obtained by the above preparation method.

[0021] In a third aspect, the application further provides an application of the reverse interface catalyst, which is used for catalyzing the hydrogenation reaction of benzene series.

[0022] Optionally, the benzene series is selected from one of benzene, xylene, toluene, benzyl toluene, and dibenzyl toluene.

[0023] Optionally, the application comprises:

[0024] The benzene series and the hydrogen source with a molar ratio of 1:3-1:6 are introduced into a reactor filled with the reverse interface catalyst, and the benzene series and the hydrogen source are subjected to a hydrogenation reaction under the conditions of 0.5-1.5 MPa and 140-180℃;

[0025] The feed air speed is 1-5 h -1 ~5h -1 , and the conversion rate of the benzene series is greater than 99.5%.

[0026] The hydrogen source includes pure hydrogen or an impurity gas containing 80-99.5% hydrogen.

[0027] The impurity component is one or more of carbon dioxide, carbon monoxide, methane, and oxygen.

[0028] Optionally, before the benzene series and the hydrogen source with a molar ratio of 1:3-1:6 are introduced into the reactor filled with the reverse interface catalyst, the method further includes:

[0029] The activation treatment of the reverse interface catalyst includes:

[0030] H2 is introduced into the reactor, and the activation is performed at 200-350℃ for 2-10 hours.

[0031] Compared with the prior art, the application has the following advantages:

[0032] The preparation method of the reverse interface catalyst provided by the application includes the following steps: a nickel salt solution is mixed with γ-Al2O3, and then the mixture is left to stand so that nickel ions are adsorbed on the γ-Al2O3 to prepare NiO / Al2O3; the NiO / Al2O3 is subjected to hydrogen reduction treatment so that the NiO is reduced to metallic nickel to obtain Ni / Al2O3; because the metallic Ni 0 surface has uncoordinated d electrons, after the Ni / Al2O3 is subjected to oxidation treatment and then immersed in a citric acid solution, the carboxyl groups (-COOH) of the citric acid can be coordinated with the nickel to form stable coordination bonds, chemical modification of the surface of the Ni / Al2O3 is realized, a modified layer is formed, the Ni surface is rich in negative carboxyl groups, and then the charge distribution and hydrophilicity of the Ni 0 surface are changed in a directional manner; and the surface-modified Ni / Al2O3 is dispersed in a cerium salt solution, because the surface-modified Ni / Al2O3 is negatively charged, the electrostatic adsorption capacity of Ce 3+ ions in the cerium salt solution can be enhanced, selective adsorption sites are provided for the Ce 3+ ions, and the Ce 3+ ions are preferentially adsorbed on the Ni surface rather than the Al2O3 carrier; the pH of the dispersion system is adjusted to be alkaline, Ce(OH)3 is generated by hydrolysis and co-precipitation of the cerium salt solution, the Ce(OH)3 is unstable under alkaline conditions and is easily oxidized to more stable Ce4+ The CeO2 precipitate is formed, and then the generated CeO2 is uniformly deposited on the surface of the metal nickel to form a close interface, thereby obtaining the reverse interface catalyst Ni@CeO2 / Al2O3. The reverse interface catalyst can be used for the hydrogenation reaction of benzene series under mild conditions of low temperature and low pressure, and the conversion rate of the benzene series reaches 99.5% or more, and the catalytic performance is excellent. The use of the reverse interface catalyst can reduce the production cost and energy consumption of the liquid organic hydrogen carrier in the field of organic liquid hydrogen storage, and has good industrial application prospects. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 A flowchart of preparation of the reverse interface catalyst provided by the embodiments of the present application is shown;

[0035] Figure 2 A hydrogen temperature-programmed reduction (H2-TPR) comparison chart provided by the embodiments and the comparative examples of the present application is shown;

[0036] Figure 3 A scanning electron microscope (SEM) chart provided by the embodiments and the comparative examples of the present application is shown, Figure 3 A and 3C show the SEM charts provided by the embodiments 1 of the present application at 5µm and 500nm, respectively, Figure 3 B and 3D show the SEM charts provided by the comparative examples 2 of the present application at 5µm and 500nm, respectively;

[0037] Figure 4 An energy dispersive spectroscopy (EDS) chart provided by the embodiments and the comparative examples of the present application is shown, Figure 4 A shows the EDS chart provided by the embodiments 1 of the present application, Figure 4 B shows the EDS chart provided by the comparative examples 2 of the present application;

[0038] Figure 5 A stability test comparison chart provided by the embodiments and the comparative examples of the present application is shown. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and in no way limits the present application and its applications or uses. Based on the embodiments in the present application, any person skilled in the art obtains any product identical or similar to the present application under the inspiration of the present application or by combining the present application with other prior art features, which falls within the protection scope of the present application. In addition, all other embodiments obtained by those skilled in the art without creative labor also fall within the protection scope of the present application.

[0040] The specific experimental steps or conditions not indicated in the embodiments can be performed according to the conventional experimental steps or conditions described in the prior art in the field. The reagents and other instruments not indicated by the manufacturer are all conventional reagent products that can be obtained by purchase. In addition, the drawings are only schematic illustrations of the embodiments of the present application, and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and thus repeated description thereof will be omitted. Some block diagrams shown in the drawings are functional entities, which do not necessarily correspond to physically or logically independent entities.

[0041] The technologies, methods and devices known to those skilled in the relevant art can not be discussed in detail, but under appropriate circumstances, the technologies, methods and devices should be regarded as part of the present application.

[0042] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as there is no conflict between them.

[0043] Currently, the catalysts for toluene hydrogenation to methylcyclohexane mainly include two categories: noble metal catalysts and non-noble metal catalysts. Noble metal catalysts, especially ruthenium (Ru)-based catalysts, exhibit excellent hydrogenation activity and selectivity, as they can achieve nearly 100% conversion of toluene and nearly 100% selectivity of methylcyclohexane under mild reaction conditions (e.g. about 120℃, 1.5 MPa), and thus are the current research focus. However, the inherent resource scarcity of noble metals leads to high cost, and in the long-term cyclic reaction process, the active components are prone to sintering, loss or carbon deposition deactivation, which seriously restricts the economic efficiency and sustainability of noble metal catalysts in large-scale industrial LOHC hydrogen storage applications. On the other hand, non-noble metal catalysts, especially nickel (Ni)-based catalysts, have been widely used in industrial catalytic hydrogenation fields (such as oil hydrogenation) due to their good hydrogenation activity and significant cost advantage, and are considered as a potential alternative to noble metal catalysts.

[0044] Although nickel-based catalysts have cost advantages, they have significant shortcomings when applied to the hydrogenation of toluene to methylcyclohexane:

[0045] Harsh reaction conditions: Compared with high-efficiency noble metal catalysts, nickel-based catalysts generally require more harsh reaction conditions, including higher reaction temperatures (usually 150-250°C or even higher) and higher operating pressures (such as 1.5-2.0 MPa or higher).

[0046] Energy consumption cost: The high-temperature and high-pressure operating mode not only leads to a significant increase in process energy consumption, reducing overall energy efficiency and economy, but also easily induces side reactions (such as cracking, deep hydrogenation, etc.) in high-temperature environments, resulting in a decrease in the selectivity and yield of the target product methylcyclohexane.

[0047] Low stability: High temperatures can significantly accelerate the migration, aggregation, and sintering of the active components of nickel-based catalysts, leading to a decrease in active sites, rapid decay of activity, and a significant reduction in service life. At the same time, local overheating and caking of the catalyst bed are prone to occur at high temperatures, not only posing a safety hazard (such as the risk of runaway hot spots), but also further exacerbating the deactivation rate of the catalyst and the complexity of equipment maintenance.

[0048] Therefore, how to break through the performance limitations of nickel-based catalysts, significantly reduce the required hydrogenation reaction conditions (achieve mild conditions close to noble metal catalysts) while maintaining their cost advantages, and effectively inhibit the sintering, aggregation, and loss of active components nickel at high temperatures, thereby significantly improving their catalytic activity, selectivity, and long-term running stability in LOHC hydrogen storage applications, has become a key scientific problem and technical bottleneck that needs to be solved in the current technical field.

[0049] In view of the problems of harsh reaction conditions, high production cost, and low stability in the related art, the present application provides a preparation method of a reverse interface catalyst, Figure 1 The preparation process of the reverse interface catalyst provided by the embodiments of the present application is shown in the flowchart Figure 1 As shown in the flowchart, the preparation method specifically includes the following steps:

[0050] S1, mix a nickel salt solution with γ-Al2O3, and then place it to allow nickel ions to be adsorbed on the γ-Al2O3, and then perform drying and calcination treatment to obtain NiO / Al2O3;

[0051] S2, reduce the NiO / Al2O3 under a hydrogen atmosphere to reduce the NiO to metallic nickel, and obtain Ni / Al2O3, and then immerse the Ni / Al2O3 in a citric acid solution after oxidation treatment, so that the carboxyl groups in the citric acid are coordinated with nickel, and then dry to obtain a surface-modified Ni / Al2O3;

[0052] S3, dispersing the surface-modified Ni / Al2O3 in a cerium salt solution, adjusting the pH of the dispersion system to alkaline, making the cerium salt solution hydrolyze, and the generated cerium dioxide uniformly deposit on the surface of the metal nickel; and obtaining the reverse interface catalyst Ni@CeO2 / Al2O3 after drying.

[0053] In some embodiments, in step S1, the nickel salt in the nickel salt solution is selected from one or more of nickel nitrate, nickel chloride, nickel acetate, and basic nickel carbonate, and the application preferably uses nickel nitrate and basic nickel carbonate.

[0054] It should be noted that in step S1, the specific surface area of the γ-Al2O3 is greater than 200 m 2 / g. The γ-Al2O3 with a high specific surface area has more micropores, mesopores, and exposed active sites on the surface. The Ni 2+ in the nickel salt solution can be combined with these sites through ion exchange, adsorption, or coordination, thereby uniformly dispersing on the surface of the γ-Al2O3 and avoiding the aggregation of nickel to form large particles, thereby preparing a reverse interface catalyst with high activity and good stability.

[0055] It should be noted that in step S2, the NiO / Al2O3 is placed in a hydrogen atmosphere for reduction treatment, and after the reduction treatment is completed, the NiO is reduced to metal nickel under an inert atmosphere, and the inert atmosphere is nitrogen and / or argon. Cooling treatment under an inert atmosphere can avoid sintering or severe oxidation of Ni 0 due to high-temperature contact with air.

[0056] It should be noted that after the Ni / Al2O3 is subjected to oxidation treatment and is immersed in a citric acid solution, the oxidation treatment refers to a slight oxidation treatment of the Ni / Al2O3 in air at 25°C to 40°C. For example, the temperature of the slight oxidation treatment can be one of 25°C, 30°C, 35°C, 40°C, or a range value of any two thereof. That is, after the slight oxidation treatment, nickel exists in the form of metal nickel and nickel oxide. The purpose of the slight oxidation is that pure Ni 0 is not easy to dissolve in the citric acid solution, and after slight oxidation, the nickel can be uniformly dissolved in the citric acid solution to facilitate the coordination reaction.

[0057] It should be noted that in step S3, the surface-modified Ni / Al2O3 is dispersed in a cerium salt solution, and the solid-liquid ratio of the Ni / Al2O3 solid to the cerium salt solution is 1:1.5 to 1:4. For example, the solid-liquid ratio can be one of 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, or a range value of any two thereof. The solid-liquid ratio of 1:1.5 to 1:4 can balance the loading amount and dispersion uniformity of cerium and improve the comprehensive performance of the reverse interface catalyst.

[0058] In specific implementation, the nickel salt is dissolved in deionized water to form a nickel salt solution, the nickel salt solution is added dropwise into γ-Al2O3 at a dropwise adding speed of 100 mL / min to 300 mL / min, stirring is performed while adding at a stirring speed of 200 r / min to 400 r / min, uniform dispersion of the solution is ensured, the impregnation is followed by standing for 12 h to 18 h, so that the nickel ions are adsorbed on the γ-Al2O3, and then drying is performed in a blast drying oven at 60 ℃ to 90 ℃ for 12 h, so that free water is removed. The dried sample is ground and placed in a muffle furnace for calcination treatment at a programmed temperature, so that NiO / Al2O3 is obtained. The NiO / Al2O3 is placed in a hydrogen atmosphere for reduction treatment, and then cooled in an inert atmosphere after the reduction treatment is completed, so that the NiO is reduced to metallic nickel, and Ni / Al2O3 is obtained. The Ni / Al2O3 is subjected to slight oxidation treatment in air at 25 ℃ to 40 ℃, and then immersed in a citric acid solution, stirring is performed until complete dissolution, impregnation is performed so that the carboxyl groups in the citric acid are coordinated with nickel, and excess free citric acid is removed by washing, and then vacuum drying is performed at 60 ℃ to 80 ℃, so that the surface-modified Ni / Al2O3 is obtained. The surface-modified Ni / Al2O3 is dispersed in a cerium salt solution, the pH of the dispersion system is adjusted to be alkaline, so that the cerium salt solution is hydrolyzed, and the generated cerium dioxide is uniformly deposited on the surface of the metallic nickel to form a close interface. Centrifugal washing is performed until neutral, and then drying is performed at 80 ℃ to 120 ℃, so that the reverse interface catalyst Ni@CeO2 / Al2O3 is obtained. The reaction formula of nickel and citric acid is as follows:

[0059]

[0060]

[0061] In the embodiment, the nickel salt solution is mixed with γ-Al2O3, standing is performed so that the nickel ions are adsorbed on the γ-Al2O3, and then NiO / Al2O3 is prepared. The NiO / Al2O3 is subjected to hydrogen reduction treatment, so that the NiO is reduced to metallic nickel, and Ni / Al2O3 is obtained. Since the metallic Ni 0 The surface exists uncoordinated d electrons, and therefore, after the slight oxidation of the Ni / Al2O3, the carboxyl groups (-COOH) of the citric acid can be coordinated with the nickel to form stable coordination bonds, chemical modification of the surface of the Ni / Al2O3 is realized, a modified layer is formed, the Ni surface is rich in negative carboxyl groups, and then the charge distribution and hydrophilicity of the nickel surface are changed in a directional manner. The surface-modified Ni / Al2O3 is dispersed in a cerium salt solution, and since the surface-modified Ni / Al2O3 is negatively charged, the electrostatic adsorption capacity of the Ce 3+ Cations in the cerium salt solution can be enhanced, so that the Ce 3+ Cations are guided to the surface of the Ni / Al2O3, and the Ce 3+Preferentially adsorbing on the surface of Ni rather than on the Al2O3 carrier, the pH of the dispersion system is adjusted to be alkaline, so that the cerium salt solution hydrolyzes and co-precipitates to generate Ce(OH)3, which is unstable under alkaline conditions and is easily oxidized to the more stable Ce 4+ , forming CeO2 precipitates, and the generated cerium dioxide can be uniformly deposited on the surface of the metal nickel to obtain a reverse interface catalyst Ni@CeO2 / Al2O3.

[0062] In some embodiments, the mass of the metal nickel in the nickel salt is 10wt%-15wt% of γ-Al2O3.

[0063] It should be noted that the mass of the metal nickel in the nickel salt is 10wt%-15wt% of γ-Al2O3. For example, the amount of metal nickel added can be one of 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt% of γ-Al2O3 or a range value of any two. In this embodiment, by controlling the mass of the metal nickel in the nickel salt to be 10-15wt% of γ-Al2O3, the number of active sites and the dispersion degree are effectively improved, the sintering of Ni particles is inhibited by metal-support interaction, the high specific surface area and porous structure of γ-Al2O3 provide a dispersion platform for Ni, while ensuring the diffusion channel of the reactant, the mass transfer efficiency is high, and then the catalyst activity, selectivity and stability of the reverse interface catalyst are good, while the economy and practicability are taken into account.

[0064] In some embodiments, in step S1, the calcination treatment temperature is 300-500°C, the heating rate is 5-10°C / min, and the calcination time is 2-4h.

[0065] It should be noted that the calcination treatment temperature is 300-500°C. For example, the calcination treatment temperature can be one of 300°C, 350°C, 380°C, 400°C, 420°C, 450°C, 500°C or a range value of any two.

[0066] It should be noted that the heating rate is 5-10°C / min. For example, the heating rate can be one of 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min or a range value of any two.

[0067] It should be noted that the calcination time is 2-4h. For example, the calcination time can be one of 2h, 2.5h, 3h, 3.5h, 4h or a range value of any two.

[0068] In the embodiment, the nickel ions are adsorbed on the γ-Al2O3, and after drying, the Ni is not in a stable form. By controlling the calcination temperature at 300-500°C, the heating rate at 5-10°C / min, and the calcination time at 2-4h, the NiO is fixed to the alumina carrier, the combination of the NiO and the alumina is more stable, the migration and sintering of the nickel in the reaction process are effectively inhibited, and the thermal stability and service life of the reverse interface catalyst are improved.

[0069] In some embodiments, in step S2, the temperature of the reduction treatment is 300-500°C, and the reduction time is 2-5h.

[0070] It should be noted that the temperature of the reduction treatment is 300-500°C. For example, the temperature of the reduction treatment can be one of 300°C, 330°C, 350°C, 400°C, 420°C, 450°C, 480°C, 500°C or a range value of any two thereof.

[0071] It should be noted that the reduction time is 2-5h. For example, the reduction time can be one of 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h or a range value of any two thereof.

[0072] It should be further noted that the NiO surface lacks free electrons. If the NiO synthesized in step S1 is directly impregnated with citric acid, the carboxyl group (-COOH) of the citric acid can only undergo weak acid-base interaction (proton exchange), and cannot form a stable coordination bond, so the citric acid cannot effectively modify the surface of the NiO, resulting in the subsequent Ce 3+ In the co-precipitation, the metal Ni 0 The surface has uncoordinated d electrons, which can form a stable coordination bond with the carboxyl group of the citric acid to achieve surface chemical modification. Therefore, the NiO in step S1 needs to be reduced to metal Ni 0 , and then reacted with the citric acid.

[0073] In the embodiment, by controlling the temperature of the reduction treatment at 300-500°C and the reduction time at 2-5h, the dissociative adsorption of H2 and the migration of oxygen atoms can be accelerated, the complete conversion of the NiO to metal Ni can be promoted, the sintering or agglomeration of the metal Ni particles due to too high surface energy can be avoided, the dispersion of the Ni and the active surface area can be improved, and the catalytic activity of the reverse interface catalyst can be improved.

[0074] In some embodiments, in step S2, the concentration of the citric acid solution is 0.1-0.5M.

[0075] It should be noted that the concentration of the citric acid solution is 0.1M-0.5M. For example, the concentration of the citric acid solution can be one of 0.1M, 0.2M, 0.3M, 0.4M, 0.5M or a range value of any two thereof.

[0076] In this embodiment, by controlling the concentration of the citric acid solution to be 0.1M-0.5M, on the one hand, citric acid can provide -COOH to form a coordination bond with Ni to form a modified layer, so that the Ni surface is rich in negative carboxyl groups, and the negative carboxyl groups provide electrostatic adsorption sites for the subsequent Ce 3+ and provides adsorption sites; on the other hand, citric acid can protect Ni 0 from converting to nickel hydroxide in the later alkaline precipitation environment; in addition, citric acid can also control dispersion and prevent particle agglomeration, etc.

[0077] In some embodiments, in step S3, the cerium salt in the cerium salt solution is selected from one or more of cerium nitrate, cerium chloride, cerium carbonate, and cerium oxalate. In this application, cerium nitrate is preferred.

[0078] In some embodiments, in step S3, the molar ratio of metallic nickel in the nickel salt solution to metallic cerium in the cerium salt solution is 4:1-1:1.

[0079] It should be noted that the molar ratio of metallic nickel in the nickel salt solution to metallic cerium in the cerium salt solution is 4:1-1:1. For example, the molar ratio can be one of 4:1, 3.5:1, 3:1, 2.5:1, 2:1, 1.5:1, 1:1 or a range value of any two thereof.

[0080] In this embodiment, by controlling the molar ratio of metallic nickel in the nickel salt solution to metallic cerium in the cerium salt solution to be 4:1-1:1, the Ni core in the reverse structure is partially wrapped by the CeO2 shell, the Ni-Ce ratio is changed to improve the coverage of CeO2. On the one hand, the interface electron transfer process is regulated, and the active exposure site is optimized; on the other hand, the stability of the surface modified Ni / Al2O3 complex can be regulated, and Ni 2+ hydrolysis or precipitation is avoided, and the co-dispersibility of the complex is improved, providing electrostatic adsorption sites for the subsequent process, laying the foundation for forming an efficient active interface, and further improving the stability and selectivity of the reverse interface catalyst.

[0081] In some embodiments, in step S3, the surface modified Ni / Al2O3 is dispersed in the cerium salt solution, and the pH of the dispersion system is adjusted to be alkaline to hydrolyze the cerium salt solution, including:

[0082] The surface-modified Ni / Al2O3 is dispersed in the cerium salt solution, ammonia water is added under heating and stirring to adjust the pH of the dispersion system to alkaline, the heating temperature is 60-80°C, the stirring rate is 200-500 r / min, and the pH of the dispersion system is 9-10.5.

[0083] It should be noted that the heating temperature is 60-80°C, and for example, the heating temperature can be one of 60°C, 65°C, 70°C, 75°C, 80°C or a range value of any two thereof.

[0084] It should be noted that the stirring rate is 200-500 r / min, and for example, the stirring rate is one of 200 r / min, 250 r / min, 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min or a range value of any two thereof.

[0085] It should be noted that the pH of the dispersion system is 9-10.5, and for example, the pH of the dispersion system is one of 9, 9.5, 10, 10.5 or a range value of any two thereof.

[0086] In specific implementation, the cerium salt is dissolved in deionized water to form a cerium salt solution, and then the surface-modified Ni / Al2O3 is dispersed in the cerium salt solution. Ammonia water is slowly added (dropping rate: 50-150 mL / min) under stirring (stirring rate: 200-500 r / min) at a constant temperature range of 60-80°C to a pH of 9-10.5, so that Ce 3+ is hydrolyzed to form Ce(OH)3 and uniformly deposited on the surface of Ni. The suspension after co-precipitation is aged for 12 hours to promote complete conversion of Ce(OH)3 to CeO2 and improve crystallinity (stabilize the crystal grains). Subsequently, centrifugal separation is performed, and repeated washing with deionized water is performed until the filtrate has a pH of about 8-9, to ensure removal of residual NH 4+ and NO 3- Finally, the obtained dry and uniform reverse interface catalyst Ni@CeO2 / Al2O3 is treated in a 100°C blast drying oven for 6-8 hours.

[0087] In this embodiment, ammonia water is added to adjust the pH of the dispersion system to 9-10.5 under heating at 60-80°C and stirring at 200-500 r / min. The heating temperature is adjusted to ensure uniform generation of cerium dioxide by controlling the diffusion and hydrolysis rate, the stirring rate is adjusted to maintain uniformity of the system to avoid local agglomeration, and ammonia water is added to provide an alkaline pH to drive the hydrolysis of Ce 3+Hydrolysis co-precipitation, enhanced interface effect to achieve efficient loading. The synergistic effect of the three can make CeO2 uniformly dispersed on the surface of Ni / Al2O3 modified by citric acid, and finally improve the activity and stability uniformity of the reverse interface catalyst material in the hydrogenation reaction.

[0088] In some embodiments, the Ni@CeO2 / Al2O3 precursor is obtained by drying, the precursor is mixed with graphite, and is pressed to form a reverse interface catalyst Ni@CeO2 / Al2O3;

[0089] The addition amount of graphite is 3wt%-8wt% of the precursor.

[0090] It should be noted that the pressure of the above pressing forming is 10MPa-15MPa, for example, it can be one of 10MPa, 11MPa, 12MPa, 13MPa, 14MPa, 15MPa or a range value of any two.

[0091] It should be noted that the addition amount of graphite is 3wt%-8wt% of the precursor, for example, it can be one of 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt% or a range value of any two. Too much graphite may occupy the active sites.

[0092] In this embodiment, by mixing the precursor with graphite and pressing forming, the addition amount of graphite is 3wt%-8wt% of the precursor, a stable physical form can be obtained, the mechanical strength is improved to adapt to industrial applications, the pore structure and specific surface area are regulated, and the active component aggregation is inhibited, which together ensures the stability, mass transfer efficiency and catalytic activity of the reverse interface catalyst in actual reaction.

[0093] In a second aspect, the application provides a reverse interface catalyst, which is obtained according to the above preparation method.

[0094] In a third aspect, the application provides an application of a reverse interface catalyst, which is used for catalyzing the hydrogenation reaction of benzene series.

[0095] In this embodiment, the reverse interface catalyst Ni@CeO2 / Al2O3 catalyzes the hydrogenation reaction of benzene series, which can efficiently convert hydrogen into high-density, safe and easy-to-store liquid naphthenes with high activity, high selectivity and stability in the field of organic hydrogen storage, while supporting the reversible cycle of hydrogen storage and release, and providing a feasible storage solution for the large-scale application of hydrogen energy.

[0096] In some embodiments, the benzene series is selected from one of benzene, xylene, toluene, benzyl toluene, and dibenzyl toluene.

[0097] It should be noted that the above hydrogenation reaction can be completed in a batch kettle, or in a fixed bed reactor.

[0098] In some embodiments, the application comprises:

[0099] Passing benzene series and hydrogen source with a molar ratio of 1:3-1:6 into a reactor filled with reverse interface catalyst, so that the benzene series and hydrogen source undergo hydrogenation reaction under the condition of 0.5 MPa-1.5 MPa, 140°C-180°C;

[0100] The feed airspeed is 1h -1 -5h -1 , and the conversion rate of benzene series is more than 99.5%;

[0101] The hydrogen source includes pure hydrogen or impurity gas containing 80%-99.5% hydrogen;

[0102] The impurity component is one or more of carbon dioxide, carbon monoxide, methane, and oxygen.

[0103] It should be noted that the liquid airspeed refers to the volume of liquid feed passing through a unit volume of catalyst per unit time (unit: h −1 ). The airspeed directly determines the residence time of benzene series and hydrogen in the catalyst bed. The feed airspeed is 1h -1 -5h -1 , for example, it can be one of 1h -1 , 1.5h -1 , 2h -1 , 3h -1 , 3.5h -1 , 4h -1 , 4.5h -1 , 5h -1 or a range value of any two.

[0104] It should be noted that the molar ratio of benzene series and hydrogen is 1:3-1:6, for example, the molar ratio can be one of 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6 or a range value of any two, which can balance the "sufficient hydrogenation" and "excess hydrogen cost" to achieve optimal hydrogen storage performance.

[0105] It should be noted that the benzene series and hydrogen source undergo hydrogenation reaction under the condition of 0.5 MPa-1.5 MPa, for example, the reaction pressure can be one of 0.5 MPa, 0.8 MPa, 1.0 MPa, 1.2 MPa, 1.5 MPa or a range value of any two.

[0106] It should be noted that the benzene series and the hydrogen source are subjected to hydrogenation reaction at 140-180°C. For example, the reaction temperature can be one of 140°C, 150°C, 160°C, 170°C, 180°C or a range value of any two thereof.

[0107] It should also be noted that the hydrogen source can be pure hydrogen or an impurity gas containing 80-99.5% hydrogen. The impurity gas is used to simulate actual industrial applications, for example: the impurity gas can be chlor-alkali industrial by-product hydrogen, refinery by-product hydrogen, natural gas steam reforming hydrogen, methanol cracking hydrogen, etc. Here, the hydrogen source is not actual industrial hydrogen production, but simulates an impurity gas containing these proportions. For example: chlor-alkali industrial by-product hydrogen is simulated to configure 0.5% O2+99.5% H2, refinery by-product hydrogen is simulated to configure 5% CH4+95% H2, etc.

[0108] The impurity gas containing 80-99.5% hydrogen, for example, the hydrogen content can be one of 80%, 83%, 85%, 88%, 90%, 92%, 95%, 98%, 99.5% or a range value of any two thereof. When the hydrogen source is an impurity gas containing 80-99.5% hydrogen, the space velocity is 1-5 h -1 -3 h -1 .

[0109] In this embodiment, the reverse interface catalyst is used for the hydrogenation reaction of the benzene series and the hydrogen source, which can be completed in a short time (30 min) in a batch kettle; in a fixed bed reactor at low temperature 140-180°C, low pressure 0.5-1.5 MPa, space velocity 1-5 h -1 -3 h -1 , the benzene series conversion rate can reach 99.5%, the reverse interface catalyst shows ultra-high reaction activity, and overcomes the problem of harsh reaction conditions and stability of non-noble metal catalysts.

[0110] In some embodiments, before the benzene series and the hydrogen source with a molar ratio of 1:3-1:6 are introduced into the reactor filled with the reverse interface catalyst, the following steps are further included:

[0111] The reverse interface catalyst is activated, including:

[0112] H2 is introduced into the reactor and activated at 200-350°C for 2-10 h.

[0113] It should be noted that pure H2 can be introduced into the reactor, or a mixed gas of H2 and N2 can be introduced into the reactor, and the volume ratio of hydrogen in the mixed gas is 1% to 20%. For example, the volume ratio of hydrogen can be one of 1%, 3%, 5%, 8%, 10%, 15%, 20% or a range value of any two thereof. It should be noted that the activation temperature is 200 to 350°C. For example, the activation temperature can be one of 200°C, 220°C, 250°C, 280°C, 300°C, 330°C, 350°C or a range value of any two thereof.

[0114] It should be noted that the activation time is 2h to 10h. For example, the activation time can be one of 2h, 3h, 4h, 5h, 8h, 10h or a range value of any two thereof.

[0115] In this embodiment, the reverse interface catalyst is activated before the hydrogenation reaction. H2 is introduced into the reactor, and activated at 200 to 350°C for 2 to 10h. Under mild conditions, NiO can be completely reduced to Ni 0 , and CeO2 migration covering active sites caused by high temperature (>350°C) can also be avoided.

[0116] In order to enable those skilled in the art to more clearly understand the present application, the reverse interface catalyst, preparation method and application thereof described in the present application are described in detail through the following examples.

[0117] Example 1

[0118] The preparation steps of the reverse interface catalyst are as follows:

[0119] S1, according to the mass of nickel salt metal nickel is 15wt% of γ-Al2O3, nickel nitrate (Ni(NO3)2·6H2O) is used as nickel salt and dissolved in deionized water to form a nickel salt solution, the nickel salt solution is added dropwise into γ-Al2O3 (S BET >200m 2 / g) at a rate of 20mL / min, stirring while adding to ensure uniform dispersion of the solution, soaking for 12h to allow nickel ions to be adsorbed on γ-Al2O3, then drying in a blast oven at 80°C for 12h to remove free moisture, and then grinding the sample and calcining in a muffle furnace at a temperature increasing rate of 8°C / min to 400°C for 4h to obtain NiO / Al2O3;

[0120] S2, the above NiO / Al2O3 is placed in a hydrogen atmosphere at 400°C for 2h reduction treatment, so that NiO is reduced to metallic nickel, and Ni / Al2O3 is obtained. After the reduction is completed, the cooled Ni / Al2O3 is cooled to room temperature under an inert gas N2 atmosphere, and the cooled Ni / Al2O3 is slightly oxidized in air at 30°C. Then citric acid is dissolved in deionized water, stirred at room temperature until completely dissolved to form a 0.1M citric acid solution, and the above slightly oxidized Ni / Al2O3 is immersed in the citric acid solution with a solid-liquid ratio of 1:4, stirred at room temperature for 4h, so that the carboxyl groups in the citric acid are coordinated with nickel, and the excess free citric acid is removed by washing. The sample is placed in a vacuum dryer at 60°C, and the surface modified Ni / Al2O3 is obtained after drying.

[0121] S3, cerium nitrate is dissolved in deionized water to form a cerium salt solution, and the above surface modified Ni / Al2O3 is dispersed in the cerium salt solution, wherein the molar ratio of metallic nickel to metallic cerium is 4:1. Ammonia water is slowly added at 80°C under constant temperature and 200r / min stirring until the pH is 9-10, and the dropwise addition rate is 100mL / min. The cerium salt solution is hydrolyzed to generate Ce(OH)3 and uniformly deposit on the surface of Ni. The co-precipitated suspension is left to stand for 12 hours to promote the complete conversion of Ce(OH)3 to CeO2, and the generated CeO2 is uniformly deposited on the surface of the metallic nickel to form a tight interface. Subsequently, centrifugal separation is adopted, and deionized water is repeatedly washed until the filtrate has a pH of about 8-9 to ensure that the residual NH 4+ and NO 3- impurities are removed, and finally dried in a 100°C blast drying oven for 8 hours to obtain a dry and uniform Ni@CeO2 / Al2O3 precursor powder. The dried precursor powder is uniformly mixed with 5wt% graphite powder, and pressed into a sheet under a pressure of 15MPa to obtain the reverse interface catalyst Ni@CeO2 / Al2O3 after drying.

[0122] Example 2

[0123] The difference between Example 2 and Example 1 is that:

[0124] In step S1, the mass of metallic nickel is adjusted to 10wt% of γ-Al2O3.

[0125] The other steps and amounts are the same as in Example 1 to obtain the reverse interface catalyst Ni@CeO2 / Al2O3.

[0126] Example 3

[0127] The difference between Example 3 and Example 1 is that:

[0128] In step S3, the molar ratio of metallic nickel to metallic cerium is adjusted to 2:1.

[0129] Other steps and amounts are the same as in Example 1, and a reverse interface catalyst Ni@CeO2 / Al2O3 is obtained.

[0130] Example 4

[0131] Example 4 differs from Example 1 in that:

[0132] The concentration of the citric acid solution in step S3 is adjusted to 0.5 M.

[0133] Other steps and amounts are the same as in Example 1, and a reverse interface catalyst Ni@CeO2 / Al2O3 is obtained.

[0134] Examples 5-6

[0135] Examples 5-6 differ from Example 1 in that:

[0136] The nickel salt in step S1 is adjusted to basic nickel carbonate and nickel chloride, respectively.

[0137] Other steps and amounts are the same as in Example 1, and a reverse interface catalyst Ni@CeO2 / Al2O3 is obtained.

[0138] Example 7

[0139] Example 7 differs from Example 1 in that:

[0140] In step S1, the calcination treatment temperature, the temperature increase rate, and the calcination time are adjusted to 350°C, 10°C / min, and 2.5 h, respectively.

[0141] Other steps and amounts are the same as in Example 1, and a reverse interface catalyst Ni@CeO2 / Al2O3 is obtained.

[0142] Example 8

[0143] Example 8 differs from Example 1 in that:

[0144] In step S1, the reduction treatment temperature and the reduction time are adjusted to 500°C and 4 h, respectively.

[0145] Other steps and amounts are the same as in Example 1, and a reverse interface catalyst Ni@CeO2 / Al2O3 is obtained.

[0146] Comparative Example 1

[0147] The preparation steps of the conventional catalyst are as follows:

[0148] S1, nickel nitrate (Ni(NO3)2·6H2O) is used as a nickel salt and dissolved in deionized water to form a nickel salt solution, cerium nitrate is used as a cerium salt and dissolved in deionized water to form a cerium salt solution, the mass of metal nickel in the nickel salt and the mass of metal cerium in the cerium salt are 20wt% of γ-Al2O3, the molar ratio of metal nickel to metal cerium is 4:1, and the solid-liquid ratio is 1:2; the nickel salt solution is first added dropwise into γ-Al2O3 (S BET >200m 2 / g) at a rate of 100mL / min, stirring while adding to ensure uniform dispersion of the solution; ammonia water is slowly added at a dropwise rate of 50mL / min to adjust the dissolution pH to 9~10, so that Ni 2+ co-precipitates on the surface of Al2O3. After precipitation for 12h, wash at pH≈8~9, dry and calcine to obtain a NiO / Al2O3 catalyst;

[0149] S2, the NiO / Al2O3 catalyst is ground and then added to deionized water, and the cerium salt solution is then added dropwise into the solution containing NiO / Al2O3 at a rate of 100mL / min, stirring while adding to ensure uniform dispersion of the solution, and ammonia water is slowly added at a dropwise rate of 50mL / min to adjust the dissolution pH to 9~10, so that Ce 3+ co-precipitates on the surface of NiO / Al2O3. After precipitation is complete, the system is allowed to stand at room temperature for 12h, and then washed by centrifugation or filtration to pH≈8~9 to remove impurity ions; finally, dry the mixture in a blast drying oven at 100℃ for 8h to obtain a dry and uniform Ni-CeO2 / Al2O3 precursor powder, mix the dry precursor powder with 5wt% graphite powder, and press into a sheet under a pressure of 15MPa, and obtain the catalyst Ni-CeO2 / Al2O3 after drying.

[0150] The activation treatment of the catalyst is as follows:

[0151] Before use, the catalyst of Comparative Example 1 is reduced at 250℃ in a 20%H2 / N2 atmosphere for 3h.

[0152] Comparative Example 2

[0153] The difference between Comparative Example 2 and Comparative Example 1 is that:

[0154] The activation treatment of the catalyst is adjusted as follows: before use, the catalyst of Comparative Example 2 is reduced at 450℃ in a 20%H2 / N2 atmosphere for 3h.

[0155] The remaining steps and amounts are the same as in Comparative Example 1, and the catalyst Ni-CeO2 / Al2O3 is obtained.

[0156] Comparative Example 3

[0157] The difference between Comparative Example 3 and Example 1 is that:

[0158] The catalyst Ni-CeO2 / Al2O3 was obtained in step S3 without citric acid solution, and other steps and amounts were the same as in Example 1.

[0159] Before use, the catalyst of Comparative Example 3 was reduced at 250°C for 3 hours in a 20% H2 / N2 atmosphere.

[0160] Figure 2 A comparison chart of the hydrogen temperature programmed reduction (H2-TPR) of Example 1 and Comparative Example 2 of the present application is shown; as shown in Figure 2 , the high peak at 300°C indicates that the reduction temperature of NiO to Ni 0 is significantly reduced, which is attributed to the modification of citric acid and the uniform deposition of CeO2, which optimizes the dispersity of NiO, enhances the H2 activation ability, and makes NiO more easily reduced at low temperature; the weak peak at 700°C is due to the removal of surface oxygen of CeO2, which confirms the successful loading of CeO2. The preparation strategy of Example 1 significantly improves the reducibility and dispersity of the active metal nickel through structural design and citric acid modification, while the simple co-precipitation of Comparative Example 2 has poor reduction performance. This phenomenon explains the higher catalytic activity that Example 1 may exhibit in low-temperature catalytic reactions.

[0161] The preparation method of the present application increases the active active sites in the reverse interface catalyst, moves the reduction peak of Ni to a low temperature by 80-120°C (as shown in Figure 1 ), and makes the active center efficiently activate hydrogen molecules at a low temperature zone (120-150°C), and the CeO2 deposition layer effectively inhibits the agglomeration of Ni particles at high temperature, limits the migration of Ni crystal grains, so as to maintain high dispersity of Ni in the reaction, thereby enhancing the stability of the reverse catalyst in the process conditions.

[0162] Figure 3 A comparison chart of the scanning electron microscope (SEM) images of Example 1 and Comparative Example 2 of the present application is shown; Figure 3 A, 3C are SEM images of Example 1 at 5µm and 500nm, respectively; Figure 3B, 3D are SEM images of Comparative Example 2 at 5 µm, 500 nm, respectively; the particles of Example 1 are more uniform, and the support Al2O3 surface is covered with fine particles (Ni@CeO2 composite structure) more uniformly, without obvious aggregation of large particles, and due to the uniform deposition of CeO2 on the surface of Ni particles, the surface may present local unevenness (CeO2 coverage leads to irregular morphology). The traditional catalyst in Comparative Example 2 generally uses a step-by-step coprecipitation method to load Ni and Ce, which leads to the active components mainly dispersed on the surface of the alumina support, and the contact between Ni and CeO2 is limited, which is prone to aggregation and unevenness; while the present application uses the innovative reverse interface construction strategy, using citric acid surface modification and controllable coprecipitation technology, to realize the uniform deposition of CeO2 on the special structure of Ni particles, so that the contact area between Ni and CeO2 is greatly increased. By precisely controlling the coprecipitation conditions, a Ni@CeO2 structure is prepared, which constructs a uniform CeO2 nanolayer on the surface of Ni, forming more active interface sites, which is in sharp contrast to the random dispersion structure of traditional catalysts. This special interface is beneficial to the activation and conversion of reactants.

[0163] Figure 4 EDS images provided by Example 1 and Comparative Example 2 of the present application are shown; Figure 4 A is the EDS image of Example 1, Figure 4 B is the EDS image of Comparative Example 2, the overlapping area of the Ni and Ce signals in Example 1, Ce and Ni are independently dispersed, and cerium is covered on nickel. While in Comparative Example 2, Ni and CeO2 are mostly randomly distributed, independently phase-separated, with relatively uniform morphology but wide particle size distribution, including relatively large particles, which may be caused by CeO2 aggregation.

[0164] Reverse interface catalyst for hydrogenation reaction

[0165] (1) Activation treatment of the catalyst:

[0166] The reverse interface catalyst Ni@CeO2 / Al2O3 obtained in each example was activated by reduction at 250°C under a 20% H2 / N2 atmosphere for 3h before use; the activation treatment of the catalyst Ni-CeO2 / Al2O3 obtained in each comparative example before use is described in the preparation process in the comparative examples.

[0167] (2) Hydrogenation reaction test of the reverse interface catalyst

[0168] The activated catalyst was loaded in a batch kettle or a fixed bed reactor, and the catalyst was mixed with porcelain balls at a ratio of 1:1 and loaded in a fixed bed reactor at 20 mL. After checking the airtightness, the molar ratio of toluene and pure hydrogen was 1:3 at 0.5-1.5 MPa, 140-180°C, and the feed space velocity was 1-5 h -1The hydrogenation reaction was tested under the conditions of the examples 1-8 and the hydrogen source of the hydrogenation reaction in the comparative examples 1-3 was pure hydrogen. The specific test conditions and results are shown in Table 1. The test results show that the toluene conversion rate of each example can reach 99.5%, the methylcyclohexane selectivity is >99.5%, and the amount of by-products (such as cracking products C1-C6 alkanes) is <0.3%, which meets the production requirements of high-purity chemicals.

[0169] In industrial practical applications, the hydrogen raw material often contains various impurities (such as O2, CO, CO2, CH4, etc.). At this time, the hydrogen containing impurities in the hydrogenation reaction is crude hydrogen, that is, an impurity gas containing 80%-99.5% hydrogen, such as hydrogen by-product in chlor-alkali industry, hydrogen by-product in refinery, hydrogen produced by natural gas steam reforming / methanol cracking, etc. Based on this, the reverse interface catalyst Ni@CeO2 / Al2O3 obtained in Example 1 is used to make the molar ratio of toluene and impurity gas containing 80%-99.5% hydrogen be 1:3 to occur hydrogenation reaction under the conditions of 0.5 MPa-1.5 MPa and 140°C-180°C; the feed space velocity is 1h -1 ~3h -1 . The specific test conditions and test results are shown in Table 2.

[0170] Table 1 Catalyst performance test results of examples 1-8 and comparative examples under pure hydrogen source

[0171]

[0172] As can be seen from Table 1, the reverse interface catalyst prepared in the present application can complete the toluene hydrogenation reaction in a short time (30 min) in a batch kettle, which is about 50% shorter than the reaction time of the traditional catalyst, effectively reducing the production cost and energy consumption.

[0173] The reverse interface catalyst prepared in Examples 1-8 and the catalysts of Comparative Examples 1-3 are tested for toluene conversion rate and methylcyclohexane selectivity at different temperatures (140°C, 160°C, 180°C) under the reaction conditions of 1.5 MPa and 1h -1 . It can be seen that the catalysts in the comparative examples perform well in batch data, such as faster hydrogenation, and the selectivity of the catalysts at 180°C is relatively low (methylcyclohexane is easy to break at 180°C). However, the reverse interface catalyst in the present examples can better overcome this problem, and the toluene conversion rate and selectivity at 180°C are both above 99%. At lower temperatures (160°C, 140°C), methylcyclohexane is not easy to crack, and the selectivity is basically above 99%, so the selectivity data of methylcyclohexane is not repeated in Table 1.

[0174] It is worth noting that, compared with Comparative Examples 1 and 2, the toluene conversion rate in Comparative Example 1 was only 65%, which is much lower than the toluene conversion rate (99.6%) in the reverse interface catalyst of Example 1. The toluene conversion rate in Comparative Example 2 reached 99%. The only difference between Comparative Examples 1 and 2 is that the activation temperature of Comparative Example 2 before use was 450°C, thus achieving a catalytic effect comparable to that of Example 1. It can be seen that the reverse interface catalyst activated at a lower temperature has excellent catalytic effect in low temperature and low pressure reactions, while the comparative examples activated at a lower temperature and low temperature and low pressure cannot show excellent performance.

[0175] Compared with Example 1, the amount of nickel added in Example 2 is reduced. Since the main active metal in the reverse interface catalyst is Ni, the reduced Ni loading will result in a corresponding decrease in the toluene conversion rate, which matches the results in Table 1.

[0176] In Examples 5 and 6, the Ni source was adjusted to basic nickel carbonate and nickel chloride, respectively. Basic nickel carbonate maintained a conversion rate similar to that of nickel nitrate (i.e., the conversion rate in Example 5 was above 99.5% at different temperatures). However, when nickel chloride was used, it could only maintain an excellent conversion rate at a high temperature of 180°C (in Example 6, the toluene conversion rate was above 98% at 180°C, but below 90% at 160°C and 140°C). The reason may be that residual Cl⁻ reacts with the CeO2 surface to form the CeOCl phase, reducing the number of oxygen vacancies and weakening the H2 activation ability. Moreover, Cl⁻ may also promote the peeling of Ni particles from the CeO2 surface, destroying the reverse interface structure.

[0177] In Examples 7 and 8, the calcination and reduction temperatures during the preparation of Ni@CeO2 / Al2O3 catalysts were controlled. The results showed that the catalyst performance was severely degraded at 500°C, mainly due to the sintering of Ni particles and the reduction of interfacial active sites.

[0178] The reverse interface catalyst prepared in this application can achieve hydrogenation reaction under relatively mild conditions of low temperature and low pressure, and the conversion rate reaches more than 99.5%, which is comparable to the catalytic effect of noble metal catalysts under mild conditions.

[0179] Table 2. Catalyst performance tests under different types of hydrogen sources obtained in Example 1.

[0180]

[0181] As shown in Table 2, the Ni@CeO2 / Al2O3 catalyst can maintain high toluene conversion rate (>95%) under the conditions of containing 0.5% O2, 2% CO, 5% CH4 or even multi-component mixed crude hydrogen (2% CO+5% CO2+5% CH4) and under relatively large space velocity, which may be attributed to the fact that the CeO2 oxygen vacancies can effectively capture O2, CO and other toxic species to prevent the irreversible oxidation or carbonylation of the Ni active sites, the CeO2 precipitate layer in the reverse interface effect inhibits the sintering of the Ni particles and promotes the H2 overflow, thereby ensuring the continuous hydrogenation capacity in the presence of impurities; the universality of the catalyst in the simulated industrial crude hydrogen is verified.

[0182] Figure 5 A comparison chart of stability tests provided by the embodiment 1 and the comparative example 2 of the present application is shown; the stability is as shown in Figure 5 The embodiment 1 still maintains the catalytic activity of more than 99% in the long-time stability test of 1128h, while the activity of the comparative example 2 is 98% at 783h, but decays to 91% at 1128h; the test results show that the embodiment 1 has more excellent long-term stability, and the surface modification and mild reduction process in the embodiment 1 significantly improve the anti-sintering and anti-carbon deposition capacity of the reverse interface catalyst, so that the reverse interface catalyst maintains high activity in long-term operation, which is superior to the comparative example 2 prepared by the traditional coprecipitation method.

[0183] In addition, under low temperature conditions, the reverse interface catalyst prepared in the present application can be reduced by more than 40℃ than the usual relatively high reaction temperature (for example, 180℃-200℃), and 25% energy consumption can be saved.

[0184] The structural advantages of the reverse interface catalyst prepared in the present application make it superior to the traditional catalyst in reaction activity, selectivity and stability, and provide a new idea for efficient catalyst design. At the same time, the preparation method has good universality and can be popularized to other metal-oxide catalytic systems, and has good industrial application prospect.

[0185] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms is not necessarily for the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the present specification.

[0186] For method embodiments, the steps recited in any aspect of a method can be executed in any order that is logically possible, though the order of steps depends on the context. Examples of contexts in which order of steps can matter include: the order of steps in a method of making a product, the order of steps in a method of using a product, the order of steps in a method of operating a machine, the order of steps in a method of operating a computer, the order of steps in a method of operating a computer program, the order of steps in a method of operating a computer program on a computer, the order of steps in a method of operating a computer program on a computer program, the order of steps in a method of operating a computer program on a computer program on a computer, the order of steps in a method of operating a computer program on a computer program on a computer program on a computer, and the order of steps in a method of operating a computer program on a computer program on a computer program on a computer program on a computer.

[0187] The reverse interface catalyst, the preparation method and the application thereof are described in detail above, and the principles and implementation manners of the present application are described by using specific examples. The above examples are only used to help understand the method and the core idea of the present application. Meanwhile, for those skilled in the art, the specific implementation manners and application ranges can be changed according to the idea of the present application. In conclusion, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A method for preparing a reverse interfacial catalyst, characterized by, The preparation method comprises the following steps: S1, mixing a nickel salt solution with γ-Al2O3, and then allowing nickel ions to be adsorbed on the γ-Al2O3 by standing, and then obtaining NiO / Al2O3 through drying and calcination treatment; S2, reducing NiO to metallic nickel by placing the NiO / Al2O3 in a hydrogen atmosphere for reduction treatment, and then obtaining Ni / Al2O3, and then immersing the Ni / Al2O3 in a citric acid solution after slight oxidation treatment, so that the carboxyl groups in the citric acid are coordinated with nickel, and then obtaining surface-modified Ni / Al2O3 after drying, and after the slight oxidation treatment, metallic nickel and oxidized nickel exist simultaneously; S3, dispersing the surface-modified Ni / Al2O3 in a cerium salt solution, adjusting the pH of the dispersion system to alkaline, and allowing the cerium salt solution to hydrolyze, so that the generated cerium dioxide is uniformly deposited on the surface of the metallic nickel; and then obtaining a reverse interface catalyst Ni@CeO2 / Al2O3 after drying.

2. The production method according to claim 1, characterized by, In step S1, the nickel salt in the nickel salt solution is selected from one or more of nickel nitrate, nickel chloride, nickel acetate, and basic nickel carbonate, and / or the mass of metallic nickel in the nickel salt is 10wt%-15wt% of the γ-Al2O3.

3. The preparation method according to claim 1, characterized in that, In step S1, the temperature of the calcination treatment is 300°C-500°C, the temperature rising rate is 5°C / min-10°C / min, and the calcination time is 2h-4h.

4. The method of claim 1, wherein, In step S2, the temperature of the reduction treatment is 300°C-500°C, and the reduction time is 2h-5h.

5. The preparation method according to claim 1, characterized in that, In step S2, the concentration of the citric acid solution is 0.1M-0.5M.

6. The method of claim 1, wherein, In step S3, the cerium salt in the cerium salt solution is selected from one or more of cerium nitrate, cerium chloride, cerium carbonate, and cerium oxalate; and / or the molar ratio of metallic nickel in the nickel salt solution to metallic cerium in the cerium salt solution is 4:1-1:

1.

7. The preparation method according to claim 1, characterized in that, In step S3, the dispersing of the surface-modified Ni / Al2O3 in the cerium salt solution and the adjusting of the pH of the dispersion system to alkaline so that the cerium salt solution hydrolyzes, comprises: dispersing the surface-modified Ni / Al2O3 in the cerium salt solution, and adding ammonia water to adjust the pH of the dispersion system to alkaline under heating and stirring conditions, the temperature of the heating is 60°C-80°C, the stirring rate is 200r / min-500r / min, and the pH of the dispersion system is 9-10.

5.

8. The method of any one of claims 1-7, wherein, further comprising: drying to obtain a Ni@CeO2 / Al2O3 precursor, mixing the precursor with graphite, and compression molding to obtain the reverse interface catalyst Ni@CeO2 / Al2O3; the addition amount of the graphite is 3wt%-8wt% of the precursor in terms of mass fraction.

9. A reverse interfacial catalyst characterized in that, The reverse interface catalyst is obtained according to the preparation method in any one of claims 1-8.

10. Use of the reverse interfacial catalyst of claim 9, wherein, The reverse interface catalyst is used for catalyzing the hydrogenation reaction of benzene series.

11. Use according to claim 10, characterized in that, The benzene series is selected from one of benzene, xylene, toluene, benzyl toluene, and dibenzyl toluene.

12. Use according to claim 11, characterized in that, The application comprises: The benzene series and hydrogen source with a molar ratio of 1:3-1:6 are introduced into a reactor filled with a reverse interface catalyst, and the benzene series and hydrogen source are subjected to a hydrogenation reaction under the conditions of 0.5-1.5 MPa and 140-180 DEG C; Feed space velocity 1 h -1 ~5 h -1 The conversion of benzene series reaches 99.5% or more; The hydrogen source comprises pure hydrogen or an impurity gas containing 80-99.5% hydrogen. The impurity component is one or more of carbon dioxide, carbon monoxide, methane and oxygen.

13. Use according to claim 12, characterized in that, Before the benzene series and hydrogen source with a molar ratio of 1:3-1:6 are introduced into the reactor filled with the reverse interface catalyst, the method further comprises: The reverse interface catalyst is subjected to an activation treatment, which comprises: H2 is introduced into the reactor, and the reactor is activated at 200-350 DEG C for 2-10 h.

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