Method and system for preparing nano carbon material from carbon dioxide
By switching between a fixed bed and a CVD reactor, carbon dioxide is converted into nanocarbon materials, and the problems of discontinuity and poor controllability in the prior art are solved, and the stable preparation and high-quality output of nanocarbon materials are achieved.
Patent Information
- Application Number
- CN202411429357.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-14
- Publication Date
- 2025-01-07
AI Technical Summary
In the prior art, the carbon dioxide conversion preparation of nanocarbon materials cannot be achieved continuously, the microstructure of nanocarbon materials is poor, and the catalyst is difficult to remove.
Methane mixed gas is generated by mixing carbon dioxide, hydrogen and inert gas in proportion and then passing into a fixed bed reactor with a low-temperature high-efficiency methanation catalyst, and then passing it into a high-temperature CVD reactor for carbon growth reaction to generate nanocarbon materials and through The catalyst was removed by pretreatment and continuous preparation was achieved by switching between fixed bed reactors and CVD reactors.
The continuous preparation and quality stability of nanocarbon materials are achieved, the requirements for use of functional materials are met, the high conversion of carbon dioxide and the selectivity of methane are improved, and the difficulty of catalyst removal is reduced.
Smart Images
Figure CN119263264A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of efficient utilization of carbon dioxide, and in particular relates to a method and system for preparing nano-carbon materials from carbon dioxide. Background Art
[0002] At present, there are only a few ways to recycle carbon dioxide, such as amination, catalytic hydrogenation, esterification, etc., and some products obtained by amination and esterification have poor molecular structure stability, short product life cycle, easy degradation and re-release of carbon dioxide. Therefore, it is still urgent to explore the technical approach to high-value utilization of carbon dioxide. Nanocarbon materials such as carbon nanotubes and graphene have mild chemical stability, diverse electrical conductivity and special thermal conductivity, which have set off a revolution in the field of materials science and technology. Carbon nanotubes have unique conductive properties, as well as metallic and semiconductor properties. They can form a honeycomb conductive network inside the coating, giving the coating excellent electronic shielding properties. Graphene has a unique lamellar structure, which can improve the anti-corrosion effect of the coating by extending the corrosion path, so that the coating has better shielding properties. Recent studies have shown that adding a relatively small amount of nanocarbon materials to the polymer matrix can significantly improve the mechanical strength, thermal stability and anti-corrosion properties of the polymer matrix. Nanocarbon materials have become one of the popular coating fillers at present, so the research on the preparation and application technology of nanocarbon materials is of great significance.
[0003] At present, there are three most commonly used methods for preparing nanocarbon materials, namely arc discharge method, laser evaporation method and catalytic cracking method. Arc discharge method and laser evaporation method both use graphite as raw material, which is expensive, has poor controllability over the microstructure of nanocarbon materials, and has insufficient product output and quality; catalytic cracking method uses carbon-containing gases such as methane as raw materials, and the reaction process is easy to control, but the obtained nanocarbon materials have many defects. During the preparation process, the catalyst particles are coated in the nanocarbon material, which makes it difficult to remove. CO2 is a renewable carbon resource with abundant reserves, safety, and pollution-free. Using chemical vapor deposition to convert it into high-value-added nanocarbon materials and realize the recycling of carbon resources is one of the main directions for addressing the greenhouse effect. Summary of the invention
[0004] The present invention is proposed to solve the problems in the prior art of the inability to continuously prepare nano-carbon materials by converting carbon dioxide and the poor controllability of nano-carbon materials. Its purpose is to provide a method for preparing nano-carbon materials by carbon dioxide.
[0005] The present invention is achieved through the following technical solutions:
[0006] A method for preparing nano-carbon materials from carbon dioxide, characterized in that:
[0007] (I) Preparation of methane mixed gas
[0008] Carbon dioxide, hydrogen and inert gas are mixed in proportion and introduced into a fixed bed reactor equipped with a low-temperature and high-efficiency methanogenic catalyst for reaction to generate a methane mixed gas, which is then dried and stored in a gas storage tank;
[0009] (II) Preparation of Nanocarbon Materials
[0010] The methane mixed gas obtained in step (I) is introduced into a high-temperature CVD reactor containing a carbon growth catalyst to carry out a carbon growth reaction to generate a fluffy powdery nano-carbon material, which is then pretreated to remove the catalyst to obtain the nano-carbon material.
[0011] In the above technical solution, before preparing the methane mixed gas in step (I), the reaction system is first purged with an inert gas, and then hydrogen is introduced to reduce the low-temperature and high-efficiency methanation catalyst and carbon growth catalyst in the reaction system.
[0012] In the above technical solution, the duration of the reduction by introducing hydrogen is 2h to 3h, and the reduction temperature is 500°C to 700°C.
[0013] In the above technical solution, the volume ratio of carbon dioxide, hydrogen and inert gas in step (I) is 1:4:2.
[0014] In the above technical scheme, the reaction conditions of the fixed bed reactor in step (I) are: reaction temperature 300°C to 450°C, reaction pressure is atmospheric pressure, volume space velocity is 8000ml·g -1 ·h -1 ~12000ml·g -1 ·h -1 .
[0015] In the above technical solution, the low-temperature and high-efficiency methanation catalyst is a nickel-based catalyst composed of multiple metals prepared by an in-situ growth method, and the multiple metals include lanthanum and cobalt.
[0016] In the above technical solution, the carbon growth catalyst is a nickel-cobalt-lanthanum based catalyst prepared by a polymer precursor method.
[0017] In the above technical scheme, the reaction conditions of the CVD reactor in step (II) are: reaction temperature 600°C to 800°C, reaction pressure is normal pressure, volume space velocity is 1800ml·g -1 ·h -1 ~2400ml·g -1 ·h -1 .
[0018] A system for preparing nano-carbon materials from carbon dioxide comprises a gas feeding mechanism, a methane reaction mechanism, a gas storage tank and a high-temperature reaction mechanism which are connected in sequence; the gas feeding mechanism comprises a carbon dioxide inlet pipeline, a hydrogen inlet pipeline and an inert gas inlet pipeline, and the gas outlet ends of the three are all connected to the gas inlet of the methane reaction mechanism; the gas outlet of the methane reaction mechanism is connected to the gas inlet of the gas storage tank; and the gas outlet of the gas storage tank is connected to the gas inlet of the high-temperature reaction mechanism.
[0019] In the above technical solution, the methane reaction mechanism includes a plurality of fixed bed reactors arranged in parallel; the high temperature reaction mechanism includes a plurality of CVD reactors arranged in parallel.
[0020] In the above technical solution, pressure gauges, flow meters and valves are provided on the carbon dioxide inlet pipeline, the hydrogen inlet pipeline and the inert gas inlet pipeline.
[0021] In the above technical solution, a valve is provided at the air inlet end of the air storage tank.
[0022] In the above technical solution, a valve and a flow meter are provided at the gas inlet end of the CVD reactor.
[0023] The beneficial effects of the present invention are:
[0024] The present invention provides a method and system for preparing nano-carbon materials from carbon dioxide, which can realize continuous preparation, and the prepared nano-carbon materials have stable quality, and can meet the use requirements of functional materials after pretreatment; the present invention utilizes the low-temperature high activity of a low-temperature and high-efficiency methanation catalyst to achieve a high conversion rate of carbon dioxide and a high selectivity of methane, utilizes the catalytic effect of a carbon growth catalyst to achieve a high yield of methane-converted nano-carbon materials, and adopts switching between a fixed bed reactor and a CVD reactor to realize continuous preparation of nano-carbon materials, and the prepared nano-carbon materials have stable quality, and can meet the use requirements of functional materials after pretreatment. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is a schematic structural diagram of a system for preparing nano-carbon materials from carbon dioxide according to the present invention;
[0026] Figure 2 is a SEM image of the nano-carbon material prepared in Example 1 of the present invention;
[0027] Figure 3 is a SEM image of the nano-carbon material prepared in Example 2 of the present invention;
[0028] Figure 4 This is a SEM image of the nano-carbon material prepared in Example 3 of the present invention.
[0029] in:
[0030] 1. Gas feeding mechanism; 2. Methane reaction mechanism; 3. Gas storage tank; 4. High temperature reaction mechanism.
[0031] For ordinary technicians in this field, other relevant drawings can be obtained based on the above drawings without any creative work. DETAILED DESCRIPTION
[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.
[0033] A system for preparing nano-carbon materials from carbon dioxide, such as Figure 1 As shown, it includes a gas feeding mechanism, a methane reaction mechanism, a gas storage tank and a high-temperature reaction mechanism that are connected in sequence; the gas feeding mechanism includes a carbon dioxide inlet pipeline, a hydrogen inlet pipeline and an inert gas inlet pipeline, and the gas outlet ends of the three are all connected to the gas inlet of the methane reaction mechanism; the gas outlet of the methane reaction mechanism is connected to the gas inlet of the gas storage tank; the gas outlet of the gas storage tank is connected to the gas inlet of the high-temperature reaction mechanism.
[0034] The methane reaction mechanism comprises a plurality of fixed bed reactors arranged in parallel; the high temperature reaction mechanism comprises a plurality of CVD reactors arranged in parallel.
[0035] The carbon dioxide inlet pipeline, the hydrogen inlet pipeline and the inert gas inlet pipeline are all provided with pressure gauges, flow meters and valves.
[0036] A valve is arranged at the air inlet end of the air storage tank.
[0037] A valve and a flow meter are provided at the gas inlet end of the CVD reactor.
[0038] A method for preparing nano-carbon materials by converting carbon dioxide comprises the following steps:
[0039] S1. The system is purged with an inert gas, and hydrogen is introduced to reduce the methanation catalyst and carbon growth catalyst loaded in the system reactor at 500°C to 700°C for 2h to 3h;
[0040] S2. Carbon dioxide, hydrogen and inert gas are mixed in a volume ratio of 1:4:2 and introduced into a fixed bed reactor (three sets of devices are used interchangeably) equipped with a low-temperature and high-efficiency methanogenic catalyst to generate a methane mixed gas, which is then dried and stored in a gas storage tank; the process conditions of the fixed bed reactor are: reaction temperature 300°C to 450°C, reaction pressure is atmospheric pressure, and volume space velocity is 8000ml·g -1 ·h -1 ~12000ml·g -1 ·h -1 ;
[0041] The low-temperature and high-efficiency methanation catalyst is a nickel-based catalyst composed of multiple metals prepared by an in-situ growth method, wherein the multiple metals include lanthanum and cobalt; the low-temperature and high-efficiency methanation catalyst is prepared by the method of patent "2024107866259-A Carbon Dioxide Methanation Catalyst and Preparation Method Thereof";
[0042] S3. The methane mixed gas in the gas storage tank is introduced into a CVD reactor (three sets of devices are replaced and used) equipped with a carbon growth catalyst for carbon growth reaction to generate fluffy powdered nano-carbon materials, and then the catalyst is removed by pretreatment to obtain nano-carbon materials; the process conditions of the CVD reactor are: reaction temperature 600°C to 800°C, reaction pressure is normal pressure, and volume space velocity is 1800ml·g -1 ·h -1～ 2400ml·g -1 ·h -1 .
[0043] Example 1
[0044] The device was purged with an inert gas, and hydrogen was introduced to reduce the methanation catalyst (La-Ni-Mg-Co perovskite catalyst) and the carbon growth catalyst (La-Ni-Mg-Co-Ca perovskite catalyst) at 650°C for 2.5 hours.
[0045] Carbon dioxide, hydrogen and inert gas are mixed in a volume ratio of 1:4:2 and then enter a fixed bed reactor to react and generate a methane mixed gas, which is then stored in a gas storage tank after drying. The process conditions of the fixed bed reactor are: reaction temperature 450°C, reaction pressure normal pressure, volume space velocity 11000ml·g -1 ·h -1 .
[0046] The methane mixed gas in the gas tank is introduced into the CVD reactor for carbon growth reaction to generate fluffy powdered nanocarbon material, and then the catalyst is removed by pretreatment to obtain nanocarbon material 1; the process conditions of the CVD reactor are: reaction temperature 750°C, reaction pressure is normal pressure, and volume space velocity is 2400ml·g -1 ·h -1 .
[0047] Example 2
[0048] The device was purged with inert gas, and hydrogen was introduced to reduce the methanogenic catalyst (La-Ni-Mg-Co perovskite catalyst) and the carbon growth catalyst (La-Ni-Mg-Co-Ca perovskite catalyst) at 650°C for 2.5 hours. Carbon dioxide, hydrogen and inert gas were mixed in a ratio of 1:4:2 and then fed into a fixed bed reactor to react and generate a methane mixed gas, which was then dried and stored in a gas storage tank; the process conditions of the fixed bed reactor were: reaction temperature 300°C, reaction pressure normal pressure, and volumetric space velocity 8000ml·g -1 ·h -1 The methane mixed gas in the gas tank enters the CVD reactor for carbon growth reaction to generate fluffy powdered nanocarbon materials, and then the catalyst is removed by pretreatment to obtain nanocarbon material 2; the process conditions of the CVD reactor are: reaction temperature 600 ° C, reaction pressure is normal pressure, volume space velocity is 1800 ml g -1 ·h -1 .
[0049] Example 3
[0050] The device was purged with an inert gas, and hydrogen was introduced to reduce the methanation catalyst (La-Ni-Mg-Co perovskite catalyst) and the carbon growth catalyst (La-Ni-Mg-Co-Ca perovskite catalyst) at 650°C for 2.5 hours.
[0051] Carbon dioxide, hydrogen and inert gas are mixed in a ratio of 1:4:2 and then enter a fixed bed reactor to react and generate a methane mixed gas, which is then stored in a gas storage tank after drying. The process conditions of the fixed bed reactor are: reaction temperature 350°C, reaction pressure normal pressure, volume space velocity 10000ml·g -1 ·h -1 .
[0052] The methane mixed gas in the gas tank is introduced into the CVD reactor for carbon growth reaction to generate fluffy powdered nanocarbon material, and then the catalyst is removed by pretreatment to obtain nanocarbon material 3; the process conditions of the CVD reactor are: reaction temperature 650°C, reaction pressure is atmospheric pressure, and volume space velocity is 2000ml·g -1 ·h -1 .
[0053] The nano-carbon materials obtained in the above three embodiments were subjected to acid washing pretreatment, and the treated samples were subjected to SEM analysis. Figures 2 to 4 As shown, it is found that the nano-carbon materials prepared in Examples 1 to 3 all present a complete carbon nanotube structure.
[0054] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.
Claims
1. A method for preparing nano-carbon materials from carbon dioxide, characterized in that: The following steps are involved: (I) Preparation of methane mixed gas Carbon dioxide, hydrogen and inert gas are mixed in proportion and introduced into a fixed bed reactor equipped with a low-temperature and high-efficiency methanation catalyst to react and generate a methane mixed gas; (II) Preparation of Nanocarbon Materials The methane mixed gas produced in step (I) is introduced into a CVD reactor containing a carbon growth catalyst to carry out a carbon growth reaction to obtain a nano-carbon material.
2. The method for preparing nano-carbon materials from carbon dioxide according to claim 1, characterized in that: Before preparing the methane mixed gas in step (I), the reaction system is first purged with an inert gas, and then hydrogen is introduced to reduce the low-temperature and high-efficiency methanation catalyst and the carbon growth catalyst in the reaction system.
3. The method for preparing nano-carbon materials from carbon dioxide according to claim 2, characterized in that: The duration of the hydrogen reduction is 2h to 3h, and the reduction temperature is 500°C to 700°C.
4. The method for preparing nano-carbon materials from carbon dioxide according to claim 1, characterized in that: The volume ratio of carbon dioxide, hydrogen and inert gas in step (I) is 1:4:
2.
5. The method for preparing nano-carbon materials from carbon dioxide according to claim 1, characterized in that: The reaction conditions of the fixed bed reactor in step (I) are: reaction temperature 300°C to 450°C, reaction pressure is normal pressure, volume space velocity is 8000ml·g -1 ·h -1 ~12000ml·g -1 ·h -1 .
6. The method for preparing nano-carbon materials from carbon dioxide according to claim 1, characterized in that: The low-temperature and high-efficiency methanation catalyst is a nickel-based catalyst composed of multiple metals prepared by an in-situ growth method.
7. The method for preparing nano-carbon materials from carbon dioxide according to claim 1, characterized in that: The carbon growth catalyst is a nickel-cobalt-lanthanum based catalyst prepared by a polymer precursor method.
8. The method for preparing nano-carbon materials from carbon dioxide according to claim 1, characterized in that: The reaction conditions of the CVD reactor in step (II) are: reaction temperature 600°C to 800°C, reaction pressure is normal pressure, volume space velocity is 1800 ml·g -1 ·h -1 ~2400ml·g -1 ·h -1 .
9. A system for preparing nano-carbon materials from carbon dioxide according to the method of any one of claims 1 to 8, characterized in that: The invention comprises a gas feeding mechanism (1), a methane reaction mechanism (2), a gas storage tank (3) and a high-temperature reaction mechanism (4) which are connected in sequence; the gas feeding mechanism (1) comprises a carbon dioxide inlet pipeline, a hydrogen inlet pipeline and an inert gas inlet pipeline, and the gas outlet ends of the three are all connected to the gas inlet of the methane reaction mechanism (2); the gas outlet of the methane reaction mechanism (2) is connected to the gas inlet of the gas storage tank (3); and the gas outlet of the gas storage tank (3) is connected to the gas inlet of the high-temperature reaction mechanism (4).
10. The system for preparing nano-carbon materials from carbon dioxide according to claim 9, characterized in that: The methane reaction mechanism (2) comprises a plurality of fixed bed reactors arranged in parallel; the high temperature reaction mechanism (4) comprises a plurality of CVD reactors arranged in parallel.