Nickel-based catalyst as well as preparation method and application thereof
By constructing a core-shell structured nickel-based catalyst and introducing rare earth and transition metal promoters into the core, the problem of easy carbon deposition and sintering of traditional nickel-based catalysts under low concentration CO/CO2 conditions was solved, achieving efficient and deep removal of CO and CO2 from the tail gas of cyclohexanol dehydrogenation, and improving the stability and activity of the catalyst.
Patent Information
- Application Number
- CN202511979925.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-02-17
AI Technical Summary
Traditional nickel-based catalysts have limited removal efficiency under low CO/CO2 concentration conditions, are prone to carbon deposition or sintering, resulting in short catalyst life and making it difficult to achieve efficient and economical tail gas purification in cyclohexanol dehydrogenation processes.
A core-shell structured nickel-based catalyst is used, with a supported nickel-based catalyst core and a mesoporous membrane material on the outer layer. Rare earth and transition metal promoters are introduced into the core. By constructing a molecular shape-selective nanoreactor, selective catalysis is achieved, avoiding contact between macromolecules and nickel active centers, combined with suitable process operating conditions.
It significantly improves the stability and activity of the catalyst, with a single-cycle operating life that is more than three times that of traditional catalysts, reducing the frequency of shutdowns and replacements, ensuring that CO and CO2 in the exhaust gas are deeply removed to below 1 ppm, and improving the online rate and safety of the unit.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of catalyst preparation, and particularly relates to a nickel-based catalyst and a preparation method and application thereof. BACKGROUND
[0002] Deep removal of trace amounts of carbon monoxide (CO) and carbon dioxide (CO2) in industrial tail gas is a key challenge in chemical production, especially in the cyclohexanol dehydrogenation process, the tail gas is rich in hydrogen (H2) and low in carbon oxide concentration, and traditional purification techniques are difficult to balance efficiency and economy. The current mainstream methods include pressure swing adsorption (PSA), amine absorption and membrane separation, but these technologies have significant limitations: PSA has poor selectivity for low-concentration CO / CO2 and high energy consumption; amine method is prone to solvent degradation and secondary pollution and requires additional energy input; membrane separation is limited by the balance between material cost and permeation flux.
[0003] In recent years, catalytic methanation technology has become a research hotspot due to its high efficiency and environmental protection. This technology converts CO and CO2 into methane (CH4) through hydrogenation, which not only reduces harmful gas emissions, but also generates usable energy gas. Nickel-based catalysts are widely used in methanation reactions due to their high activity and cost advantage. For example, supported nickel catalysts (such as Ni / Al2O3) exhibit excellent performance in syngas (CO / H2) methanation. However, traditional nickel-based catalysts have limited removal efficiency for low-concentration CO / CO2 (<1%), and are prone to deactivation due to carbon deposition or sintering during long-term operation, especially under low-concentration CO / CO2 conditions. SUMMARY
[0004] The technical problem to be solved by the present application is to provide a nickel-based catalyst and a preparation method and application thereof. The nickel-based catalyst of the present application can deeply remove CO and CO2 from mixed gas with low CO / CO2 concentration, and the catalyst is not prone to carbon deposition or sintering, and has a long service life.
[0005] To solve the above technical problems, the present application provides a nickel-based catalyst, the particles of the nickel-based catalyst comprising: a core comprising: a carrier, nickel, a first metal additive and a second metal additive, the nickel, the first metal additive and the second metal additive being loaded on the carrier, the first metal additive being a rare earth metal, and the second metal additive being a transition metal; and a shell coated on the surface of the core, the shell being a mesoporous membrane material.
[0006] Further, the loading amount of nickel is 10%-25%, the loading amount of the first metal additive is 1%-5%, and the loading amount of the second metal additive is 0.5%-3%.
[0007] Further, the first metal additive is selected from at least one of lanthanum, cerium, yttrium, samarium and gadolinium.
[0008] Further, the second metal promoter is at least one selected from iron, cobalt, ruthenium and manganese.
[0009] Further, the carrier is at least one selected from alumina, magnesia, zirconia and ceria.
[0010] Further, the thickness of the shell is 20-40 nm.
[0011] Further, the diameter of the pore of the pore film material is 2-5 nm.
[0012] Further, the mesoporous film material is mesoporous silica.
[0013] The application also provides a method for preparing the above-mentioned nickel-based catalyst, comprising the following steps: step S1, loading nickel, a first metal promoter and a second metal promoter on a carrier according to a set mass to obtain a core; and step S2, coating the surface of the core with a mesoporous film.
[0014] Further, in step S1, the core is prepared by using an equal-volume impregnation method.
[0015] Further, in step S2, the mesoporous film is mesoporous silica, and the method for coating the surface of the core with a layer of mesoporous silica comprises the following steps: dispersing the core in an ethanol-water solution containing a template agent and tetraethyl orthosilicate, hydrolyzing and condensing under alkaline conditions by using a Stober method to controllably deposit a layer of mesoporous silica on the surface of the core, and after filtration, washing and drying, calcining to remove the template agent to prepare a nickel-based catalyst with a shell-core structure.
[0016] The application also provides an application of the above-mentioned nickel-based catalyst in removing carbon monoxide and carbon dioxide in a cyclohexanol dehydrogenation tail gas.
[0017] Further, in the reaction of removing carbon monoxide and carbon dioxide in a cyclohexanol dehydrogenation tail gas, the reaction temperature is 200-300℃, the reaction pressure is 0.1-3 MPa, the volume space velocity is 3000-10000 h-1, and the reaction time is 0.1-10 h. -1 -10000h -1 .
[0018] The application has the following beneficial effects: The nickel-based catalyst of this application creates a "nanoreactor" with molecular shape selectivity by constructing a core-shell structure with a mesoporous membrane as the shell and a supported nickel-based catalyst as the core. Selective catalysis is achieved through the molecular sieving and diffusion confinement effects of the shell channels. Small molecules (such as H2, CO, CO2, and H2O) can freely pass through the shell channels into the core to contact the Ni active sites and undergo methanation, while larger compounds such as cyclohexanol and cyclohexanone are effectively blocked outside the shell and cannot contact the nickel active sites in the core. This physical "geometric confinement" creates a unique catalytic effect. This effect eliminates the contact between macromolecules and nickel active centers at the source, fundamentally solving the problems of catalyst cracking and coking, and improving catalyst stability. The single-cycle operating life of the nickel-based catalyst in this application can reach more than three times that of traditional catalysts, greatly reducing the frequency of shutdown and replacement, and improving the online rate of the unit. Moreover, since the competitive adsorption of hydrocarbons and side reactions are avoided (the temperature rise of the catalyst bed mainly comes from the methanation reaction), the thermodynamic behavior becomes controllable and mild, completely eliminating the risk of "runaway temperature" caused by the superposition of multiple strong exothermic reactions, and ensuring the safety and controllability of the entire removal process.
[0019] By introducing rare earth metal additives such as lanthanum (La) and cerium (Ce) and transition metal additives such as iron (Fe) and cobalt (Co) into the core, the rare earth metal additives such as La / Ce mainly act as structural additives, which can significantly improve the surface defect degree and thermal stability of the alumina support. The transition metal additives such as Fe / Co act as electronic additives, forming alloys with nickel, fine-tuning the electron density of nickel, optimizing its adsorption strength and hydrogenation pathway for CO / CO2 molecules, thereby reducing the reaction energy barrier and further improving the intrinsic activity and selectivity of the methanation reaction. The bimetallic additives have synergistic and complementary functions, which greatly improves the low-temperature activity of the nickel-based catalyst.
[0020] Furthermore, the highly efficient active sites modified with bimetallic additives, combined with the carbon-free reaction environment created by the shell structure, ensure that the catalyst's active sites remain highly efficient and stable during long-term operation. This allows the total concentration of CO and CO2 in the cyclohexanol dehydrogenation tail gas to be continuously and stably removed to below 1 ppm, providing a high-purity hydrogen source for downstream processes or protecting sensitive catalysts.
[0021] The nickel-based catalyst in this application is not a simple improvement on general methanation catalysts, but a targeted design for the special chemical environment of "cyclohexanol dehydrogenation tail gas". From the microstructure of the catalyst (core-shell structure and two metal promoters introduced in the core) to the macroscopic process operating conditions (medium temperature and pressure), a complete technical system that is compatible and synergistic has been formed, which systematically solves the industry pain points in this scenario. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below in conjunction with the embodiments of this disclosure. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.
[0023] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components.
[0024] Definitions of other specific words and phrases are provided throughout this disclosure. Those skilled in the art will understand that, in many, if not most, cases, such definitions apply to the prior and future use of the words and phrases thus defined.
[0025] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
[0026] In this application, the term "loading of a certain metal" refers to the mass of active metal element loaded on a unit mass of catalyst.
[0027] This disclosure provides a nickel-based catalyst. The nickel-based catalyst particles include a core and a shell. The core includes a support, nickel, a first metal additive, and a second metal additive. The nickel, the first metal additive, and the second metal additive are all loaded on the support. The first metal additive is a rare earth metal, and the second metal additive is a transition metal. The shell covers the surface of the core and is a mesoporous membrane material.
[0028] The nickel-based catalysts provided in the above embodiments of this disclosure create a "nanoreactor" with molecular shape selectivity by constructing a core-shell structure with a mesoporous membrane as the shell and a supported nickel-based catalyst as the core. Selective catalysis is achieved through the molecular sieving and diffusion confinement effects of the shell channels. Small molecules (such as H2, CO, CO2, and H2O) can freely pass through the shell channels into the core to contact the Ni active sites and undergo methanation, while larger compounds such as cyclohexanol and cyclohexanone are effectively blocked outside the shell and cannot contact the nickel active sites in the core. This physical "geometric" effect... The "confined" effect eliminates contact between macromolecules and nickel active centers at the source, fundamentally solving the problems of catalyst cracking and coking, and improving catalyst stability. The nickel-based catalyst of this application has a single-cycle operating life of more than three times that of traditional catalysts, greatly reducing the frequency of shutdowns and replacements and improving the online rate of the unit. Moreover, since competitive adsorption of hydrocarbons and side reactions are avoided (the temperature rise of the catalyst bed mainly comes from the methanation reaction), the thermodynamic behavior becomes controllable and mild, completely eliminating the risk of "runaway temperature" caused by the superposition of multiple strong exothermic reactions, and ensuring the safety and controllability of the entire removal process.
[0029] By introducing rare earth metal additives such as lanthanum (La) and cerium (Ce) and transition metal additives such as iron (Fe) and cobalt (Co) into the core, the rare earth metal additives such as La / Ce mainly act as structural additives, which can significantly improve the surface defect degree and thermal stability of the alumina support. The transition metal additives such as Fe / Co act as electronic additives, forming alloys with nickel, fine-tuning the electron density of nickel, optimizing its adsorption strength and hydrogenation pathway for CO / CO2 molecules, thereby reducing the reaction energy barrier and further improving the intrinsic activity and selectivity of the methanation reaction. The bimetallic additives have synergistic and complementary functions, which greatly improves the low-temperature activity of the nickel-based catalyst.
[0030] Furthermore, the highly efficient active sites modified with bimetallic additives, combined with the carbon-free reaction environment created by the shell structure, ensure that the catalyst's active sites remain highly efficient and stable during long-term operation. This allows the total concentration of CO and CO2 in the cyclohexanol dehydrogenation tail gas to be continuously and stably removed to below 1 ppm, providing a high-purity hydrogen source for downstream processes or protecting sensitive catalysts.
[0031] The nickel-based catalyst in this application is not a simple improvement on general methanation catalysts, but a targeted design for the special chemical environment of "cyclohexanol dehydrogenation tail gas". From the microstructure of the catalyst (core-shell structure and two metal promoters introduced in the core) to the macroscopic process operating conditions (medium temperature and pressure), a complete technical system that is compatible and synergistic has been formed, which systematically solves the industry pain points in this scenario.
[0032] In some embodiments, the nickel loading is 10%-25%, the first metal additive loading is 1%-5%, and the second metal additive loading is 0.5%-3%. For example, the nickel loading can be 10%, 13%, 15%, 17%, 20%, 22%, 25%, etc. The first metal additive loading can be 1%, 2%, 3%, 4%, 5%, etc. The second metal additive loading can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, etc.
[0033] In some embodiments, the first metal additive is selected from at least one of lanthanum (La), cerium (Ce), yttrium (Y), samarium (Sm), and gadolinium (Gd). Preferably, the first metal additive is selected from at least one of lanthanum (La) and cerium (Ce).
[0034] In some embodiments, the second metal additive is selected from at least one of iron (Fe), cobalt (Co), ruthenium (Ru), and manganese (Mn). Preferably, the second metal additive is selected from at least one of iron (Fe) and cobalt (Co).
[0035] In some embodiments, the support is selected from at least one of alumina, magnesium oxide, and zirconium oxide. As an example, the support can be a single support such as γ-Al2O3 or magnesium oxide, or a composite support such as Al2O3-ZrO2 or ZrO2-MgO.
[0036] In some embodiments, the shell thickness is 20nm-40nm. As an example, the shell thickness can be 20nm, 25nm, 30nm, 35nm, 40nm, etc.
[0037] In some embodiments, the diameter of the pores in the mesoporous membrane material is 2nm-5nm.
[0038] In some embodiments, the mesoporous membrane material is mesoporous silica. It should be explained that the mesoporous membrane material can also be other silicon-based mesoporous materials besides silica, metal oxide mesoporous membranes (e.g., titanium dioxide, zirconium oxide, alumina), carbon-based mesoporous membranes (e.g., mesoporous carbon), etc., as long as they can prevent macromolecules from entering the core and can withstand a certain temperature, and can provide a reaction environment for the active metal without carbon buildup interference.
[0039] This disclosure also provides a method for preparing the above-mentioned nickel-based catalyst. The method for preparing the nickel-based catalyst includes the following steps: Step S1, loading nickel, a first metal promoter, and a second metal promoter onto a support according to a set mass to obtain a core; Step S2, coating the surface of the core with a mesoporous membrane.
[0040] In some embodiments, in step S1, the kernel is prepared using an equal-volume impregnation method.
[0041] Specifically, the equal-volume impregnation method includes the equal-volume co-volume impregnation method and the equal-volume sequential impregnation method.
[0042] As an example, the steps for preparing the core using the equal-volume co-impregnation method include: preparing a mixed aqueous solution using nickel nitrate, a first metal additive nitrate, and a second metal additive nitrate as precursors, according to the target loading. This solution is added dropwise to the γ-Al₂O₃ support, ensuring the liquid volume equals the total pore volume of the support. The impregnated sample is allowed to stand at room temperature for 12 hours, then dried at 120°C for 6 hours, and finally calcined at 400°C in air for 4 hours to obtain the catalyst precursor.
[0043] It should be explained that in step S1, in addition to the equal volume impregnation method, the kernel preparation method can also use common loading methods such as the excess solution impregnation method and the deposition-precipitation method.
[0044] In some embodiments, in step S2, the mesoporous membrane is mesoporous silica, and the method of coating the core surface with a layer of mesoporous silica includes the following steps: dispersing the core in an ethanol-water solution containing a template agent and tetraethyl orthosilicate, hydrolyzing and condensing it under alkaline conditions by the Stuber process, controllingly depositing a layer of mesoporous silica on the core surface, filtering, washing, drying, and calcining to remove the template agent, thereby obtaining a nickel-based catalyst with a core-shell structure.
[0045] Specifically, the template agent is a template agent that can generate 2nm-5nm mesopores, such as cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and alkyl polyoxyethylene ethers (such as the Brij series).
[0046] This disclosure also provides an application of a nickel-based catalyst in the removal of carbon monoxide and carbon dioxide from the tail gas of cyclohexanol dehydrogenation.
[0047] As an example, the steps for removing carbon monoxide and carbon dioxide from the tail gas of cyclohexanol dehydrogenation are as follows: a nickel-based catalyst is packed into a fixed-bed reactor, and the tail gas from the cyclohexanol dehydrogenation section (after condensation and recovery of most organic matter) is passed through the catalyst bed. The principle for treating CO and CO2 in the tail gas is as follows: the tail gas from the cyclohexanol dehydrogenation section contains a large amount of hydrogen. Under the action of the catalyst, the CO and CO2 in the cyclohexanol dehydrogenation tail gas are deeply hydrogenated to generate CH4 and H2O.
[0048] In some embodiments, in the reaction to remove carbon monoxide and carbon dioxide from the tail gas of cyclohexanol dehydrogenation, the reaction temperature is 200℃-300℃, the reaction pressure is 0.1MPa-3MPa (absolute pressure), and the volume hourly space velocity is 3000 h⁻¹. -1 -10000h -1 As an example, the reaction temperature can be 200℃, 220℃, 230℃, 240℃, 250℃, 260℃, 280℃, 290℃, 300℃, etc. Preferably, the reaction temperature is 220℃-260℃. This achieves good exhaust gas purification efficiency while also considering energy consumption and equipment requirements.
[0049] Specifically, the reaction temperature of 200℃ is the rapid activation point of the catalyst. The core-shell structure of the catalyst makes the active center more efficient, and the bimetallic promoter optimizes the reaction pathway, enabling the catalyst to have high activity at a lower temperature. The reaction temperature of 220℃ is the starting point for efficient purification by the catalyst. Traditional catalysts only begin to activate near this temperature, while the catalyst of this application can achieve efficient purification.
[0050] The optimal activity range for the catalyst is 240℃-280℃, where both reaction kinetics and thermodynamics are favorable. The mesoporous SiO2 shell effectively isolates macromolecules such as cyclohexanol, preventing carbon deposition and active site coverage, which is crucial for maintaining deep purification. The synergistic effect of bimetallic promoters (such as La and Co) and the core-shell structure enables the catalyst to maintain ultra-high and stable activity within this range. The catalyst of this application remains stable over a wide high-temperature range, demonstrating its excellent resistance to sintering and carbon deposition.
[0051] The reaction temperature above 300℃ is the high-temperature stability region of the catalyst. Due to the protective effect of the shell, the catalyst of this application can maintain extremely high purification efficiency at 300℃, avoiding the performance degradation that may occur with traditional catalysts.
[0052] The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Where techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.
[0053] Example 1 Preparation of nickel-based catalysts: Step S1: Using the equal-volume co-impregnation method, nickel nitrate, lanthanum nitrate, and iron nitrate are used as precursors. A mixed aqueous solution is prepared according to the target loading (Ni is 15 wt%, La is 3 wt%, and Fe is 2 wt%). The mixed aqueous solution is added dropwise to the spherical γ-Al2O3 support so that the liquid volume is equal to the total pore volume of the support. After impregnation, the solution is allowed to stand for 12 hours, dried at 120°C for 6 hours, and then calcined at 400°C in air for 4 hours to obtain the Ni-La-Fe / Al2O3 precursor.
[0054] In step S2, the Ni-La-Fe / Al2O3 precursor prepared in step S1 is dispersed in an ethanol-water solution containing hexadecyltrimethylammonium bromide (CTAB) and tetraethyl orthosilicate (TEOS), and hydrolyzed and condensed under alkaline conditions by the Stuber process to controllably deposit a layer of SiO2 on the particle surface.
[0055] Step S3: The solution prepared in step S2 is filtered, washed, and dried, then calcined at 550°C to remove the template agent, thus obtaining a nickel-based catalyst with a mesoporous SiO2 shell. The thickness of the mesoporous SiO2 shell is approximately 30 nm, and the average pore size is approximately 3 nm.
[0056] Example 2 Preparation of nickel-based catalysts: Step S1: Using the equal-volume co-impregnation method, nickel nitrate, lanthanum nitrate, and cobalt nitrate are used as precursors. A mixed aqueous solution is prepared according to the target loading (Ni is 10 wt%, La is 1 wt%, and Co is 3 wt%). The mixed aqueous solution is added dropwise to the spherical γ-Al2O3 support so that the liquid volume is equal to the total pore volume of the support. After impregnation, the solution is allowed to stand for 12 hours, dried at 120°C for 6 hours, and then calcined at 400°C in air for 4 hours to obtain the Ni-La-Co / Al2O3 precursor.
[0057] In step S2, the Ni-La-Fe / Al2O3 precursor prepared in step S1 is dispersed in an ethanol-water solution containing sodium dodecyl sulfate (SDS) and tetraethyl orthosilicate (TEOS), and hydrolyzed and condensed under alkaline conditions by the Stuber process to controllably deposit a layer of SiO2 on the particle surface.
[0058] Step S3: The solution prepared in step S2 is filtered, washed, and dried, then calcined at 550°C to remove the template agent, thereby obtaining a nickel-based catalyst with a mesoporous SiO2 shell. The thickness of the mesoporous SiO2 shell is approximately 40 nm, and the average pore size is approximately 2 nm.
[0059] Example 3 Preparation of nickel-based catalysts: Step S1: Using the equal-volume co-impregnation method, nickel nitrate, cerium nitrate, and iron nitrate are used as precursors. A mixed aqueous solution is prepared according to the target loading (Ni is 25 wt%, Ce is 5 wt%, and Fe is 0.5 wt%). The mixed aqueous solution is added dropwise to the spherical γ-Al2O3 support so that the liquid volume is equal to the total pore volume of the support. After impregnation, the solution is allowed to stand for 12 hours, dried at 120°C for 6 hours, and then calcined at 400°C in air for 4 hours to obtain the Ni-Ce-Fe / Al2O3 precursor.
[0060] In step S2, the Ni-Ce-Fe / Al2O3 precursor prepared in step S1 is dispersed in an ethanol-water solution containing hexadecyltrimethylammonium bromide (CTAB) and tetraethyl orthosilicate (TEOS), and hydrolyzed and condensed under alkaline conditions by the Stuber process to controllably deposit a layer of SiO2 on the particle surface.
[0061] Step S3: The solution prepared in step S2 is filtered, washed, and dried, then calcined at 550°C to remove the template agent, thereby obtaining a nickel-based catalyst with a mesoporous SiO2 shell. The thickness of the mesoporous SiO2 shell is approximately 20 nm, and the average pore size is approximately 5 nm.
[0062] Comparative Example Using an equal-volume impregnation method, nickel nitrate was used as a precursor. An aqueous solution was prepared according to the target loading (Ni = 15 wt%) and added dropwise to a spherical γ-Al2O3 support. After impregnation, the support was allowed to stand for 12 hours, dried at 120°C for 6 hours, and then calcined at 400°C in air for 4 hours to obtain a Ni / Al2O3 catalyst with a Ni loading of 15 wt%.
[0063] Performance testing The catalysts prepared in Examples 1-3 and the comparative example were respectively loaded into fixed-bed reactors of the same type, with the same loading volume. The treatment of the tail gas after cyclohexanol dehydrogenation (composition: H2 80%, CO 0.5%, CO2 1.0%, cyclohexanone 500 ppm, cyclohexanol 500 ppm, balance N2) was simulated. The tail gas treatment was conducted at a temperature of 250°C, a pressure of 0.5 MPa, and a space velocity of 5000 h⁻¹. -1The system was operated under the following conditions: the concentration of CO+CO2 in the gas exiting the fixed-bed reactor was measured initially (when the gas just exited the fixed-bed reactor), after 500 hours of continuous operation, and after 1500 hours of continuous operation. The measurement results are shown in Table 1.
[0064] Table 1.
[0065] As shown in Table 1, the catalysts prepared in Examples 1 to 3 could initially remove the CO+CO2 concentration in the tail gas to below 1 ppm, while the comparative example could only remove it to below 5 ppm. After 1500 hours of continuous operation using the catalysts prepared in Examples 1 to 3, the CO+CO2 concentration in the outlet gas of the fixed-bed reactor remained stable below 1 ppm, and no significant carbon buildup was observed when the catalyst was removed after stopping the reaction. However, after 500 hours of continuous operation using the catalyst prepared in the comparative example, the CO+CO2 concentration in the outlet gas of the fixed-bed reactor reached 50 ppm, and the bed pressure drop increased. Significant carbon buildup was observed on the catalyst after removal.
[0066] Example 4 The catalyst prepared in Example 1 was packed into a fixed-bed reactor. Tail gas from the cyclohexanol dehydrogenation stage (composition: H2 80%, CO 0.5%, CO2 1.0%, cyclohexanone 500 ppm, cyclohexanol 500 ppm, balance N2) was passed through the catalyst bed in the fixed-bed reactor. The reaction temperature was 200°C, the pressure was 0.5 MPa (absolute pressure), and the space velocity was 5000 h⁻¹. -1 The concentration of CO+CO2 in the gas at the outlet of the fixed-bed reactor was measured at the initial moment (when the gas just came out of the fixed-bed reactor outlet), and its purification efficiency was calculated to reach 95.12%.
[0067] Example 5 The parts of Example 5 that are the same as those in Example 4 are omitted. The differences between Example 5 and Example 4 are as follows: During exhaust gas treatment, the temperature is 220℃. The initial concentration of CO+CO2 in the gas exiting the fixed-bed reactor is measured, and the purification efficiency is calculated to reach 98.01%.
[0068] Example 6 The parts of Example 6 that are the same as those in Example 4 are omitted. The differences between Example 6 and Example 4 are: During exhaust gas treatment, the temperature is 240℃. The initial concentration of CO+CO2 in the gas exiting the fixed-bed reactor is measured, and the purification efficiency is calculated to reach 99.93%.
[0069] Example 7 The parts of Example 7 that are the same as those in Example 4 are omitted. The differences between Example 7 and Example 4 are as follows: During exhaust gas treatment, the temperature is 260℃. The initial concentration of CO+CO2 in the gas exiting the fixed-bed reactor is measured, and the purification efficiency is calculated to reach 99.95%.
[0070] Example 8 The parts of Example 8 that are the same as those in Example 4 are omitted. The differences between Example 8 and Example 4 are as follows: During exhaust gas treatment, the temperature is 280℃. The initial concentration of CO+CO2 in the gas exiting the fixed-bed reactor is measured, and the purification efficiency is calculated to reach 99.93%.
[0071] Example 9 The parts of Example 9 that are the same as those in Example 4 are omitted. The differences between Example 9 and Example 4 are as follows: During exhaust gas treatment, the temperature is 300℃. The initial concentration of CO+CO2 in the gas exiting the fixed-bed reactor is measured, and the purification efficiency is calculated to reach 99.87%.
[0072] Data from Examples 4 to 9 show that as the temperature increases, the concentration of CO+CO2 in the outlet gas of the fixed-bed reactor gradually decreases, and the purification efficiency gradually increases. After reaching 300°C, the concentration of CO+CO2 in the outlet gas of the fixed-bed reactor decreases slightly. This indicates that the catalyst of this application has excellent adaptability over a wide range.
[0073] The text in this disclosure is provided by way of example only to aid in understanding this disclosure. It should not be construed as limiting the scope of this disclosure in any way. Although certain embodiments and examples have been provided, it will be clear to those skilled in the art, based on the content disclosed herein, that changes can be made to the illustrated embodiments and examples without departing from the scope of this disclosure.
[0074] Although this disclosure has been described with reference to exemplary embodiments, various changes and modifications may be suggested to those skilled in the art. This disclosure is intended to cover such changes and modifications that fall within the scope of the appended claims.
[0075] Nothing described in this disclosure should be construed as implying that any particular element, step, or function is an essential element that must be included within the scope of the claims. The scope of the patent subject matter is defined only by the claims.
Claims
1. A nickel-based catalyst, characterized in that, The nickel-based catalyst particles comprise: The core comprises: a carrier, nickel, a first metal additive, and a second metal additive, wherein the nickel, the first metal additive, and the second metal additive are all loaded on the carrier, the first metal additive is a rare earth metal, and the second metal additive is a transition metal; A shell, which covers the surface of the core, is a mesoporous membrane material.
2. The nickel-based catalyst according to claim 1, characterized in that, The nickel loading is 10%-25%, the first metal additive loading is 1%-5%, and the second metal additive loading is 0.5%-3%.
3. The nickel-based catalyst according to claim 1, characterized in that, The first metal additive is selected from at least one of lanthanum, cerium, yttrium, samarium, and gadolinium.
4. The nickel-based catalyst according to claim 1, characterized in that, The second metal additive is selected from at least one of iron, cobalt, ruthenium, and manganese.
5. The nickel-based catalyst according to claim 1, characterized in that, The carrier is selected from at least one of alumina, magnesium oxide, zirconium oxide, and cerium dioxide.
6. The nickel-based catalyst according to claim 1, characterized in that, The thickness of the shell is 20nm-40nm.
7. The nickel-based catalyst according to claim 1, characterized in that, The diameter of the pores in the mesoporous membrane material is 2nm-5nm.
8. The nickel-based catalyst according to claim 1, characterized in that, The mesoporous membrane material is mesoporous silicon dioxide.
9. A method for preparing the nickel-based catalyst according to any one of claims 1-8, characterized in that, Includes the following steps: Step S1: Nickel, the first metal additive, and the second metal additive are loaded onto the carrier according to a set mass to obtain the core; Step S2: Coat the surface of the kernel with a mesoporous membrane.
10. The method according to claim 9, characterized in that, In step S1, the kernel is prepared using the equal-volume impregnation method.
11. The method according to claim 9, characterized in that, In step S2, the mesoporous membrane is mesoporous silica, and the method of coating the core surface with a layer of mesoporous silica includes the following steps: The core is dispersed in an ethanol-water solution containing a template agent and tetraethyl orthosilicate, and hydrolyzed and condensed under alkaline conditions by the Stuber process. A layer of mesoporous silica is controllably deposited on the surface of the core. After filtration, washing, drying, and calcination to remove the template agent, a nickel-based catalyst with a core-shell structure is obtained.
12. The use of the nickel-based catalyst according to any one of claims 1-8 in the removal of carbon monoxide and carbon dioxide from the tail gas of cyclohexanol dehydrogenation.
13. The application according to claim 12, characterized in that, In the reaction to remove carbon monoxide and carbon dioxide from the tail gas of cyclohexanol dehydrogenation, the reaction temperature was 200℃-300℃, the reaction pressure was 0.1MPa-3MPa, and the volume hourly space velocity was 3000h⁻¹. -1 -10000h -1 .