Catalyst and method for making same, method for making alkanes using carbon dioxide
By using a bimetallic catalyst supported on natural clay in a plasma treatment method, the problem of low carbon dioxide conversion efficiency was solved, achieving efficient conversion of carbon dioxide to alkanes and reducing catalyst production costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TSINGHUA UNIVERSITY
- Filing Date
- 2026-04-13
- Publication Date
- 2026-06-05
AI Technical Summary
Existing catalytic systems suffer from low conversion efficiency, poor product selectivity, and harsh reaction conditions when converting carbon dioxide into alkanes, making it difficult to achieve high-value conversion of carbon dioxide efficiently.
A plasma treatment method was adopted, using natural clay as a carrier to load a first metal component for catalytic hydrogen cracking and a second metal component for catalytic carbon dioxide activation, with the mass ratio of the two controlled at 1:(0.01-0.5), forming a heterogeneous catalytic interface with dual-site synergy. The carrier structure was optimized by acid and alkali treatment to reduce production costs.
It improves the conversion rate and product selectivity of carbon dioxide, while significantly reducing the production cost of the catalyst, thus achieving the efficient conversion of carbon dioxide into alkanes.
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Figure CN122145259A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of carbon dioxide conversion, specifically to catalysts and their preparation methods, and methods for preparing alkanes using carbon dioxide. Background Technology
[0002] Targeted conversion of atmospheric carbon dioxide into hydrocarbons can effectively reduce the concentration of greenhouse gases in the atmosphere while obtaining high-value-added fuels and basic chemical raw materials. It is one of the sustainable development paths that combines carbon emission reduction and resource value-added.
[0003] However, carbon dioxide molecules are characterized by high thermodynamic inertness and strong molecular symmetry, which means that the selective breaking of carbon-oxygen double bonds within the molecule requires overcoming a high energy barrier. Currently available catalytic systems generally suffer from problems such as low conversion efficiency, poor product selectivity, and harsh reaction conditions, making it difficult to efficiently convert carbon dioxide into alkanes (such as methane). Related technologies need further improvement.
[0004] It should be noted that the above statements are only used to provide background information related to this application and do not necessarily constitute prior art. Summary of the Invention
[0005] In a first aspect of this application, a method for preparing alkanes using carbon dioxide is provided, the method comprising plasma treatment; the plasma treatment comprising adding a catalyst; the catalyst comprising natural clay and an active metal located on the surface of the natural clay; the active metal comprising a first metal component for catalytic hydrogen cracking and a second metal component for catalytic carbon dioxide activation; wherein the mass ratio of the first metal component to the second metal component in the catalyst is 1:(0.01-0.5).
[0006] In addition to silicon and aluminum oxides, natural clay itself contains active metal components such as iron, manganese, and cobalt, which can provide a partial source of active metals. Based on this, by further controlling the mass ratio of the first metal component to the second metal component in the catalyst within the aforementioned range, active metals that can strongly interact with H2 and CO2 are used as metal sites for catalytic H2 cracking and CO2 activation, respectively, serving as a heterogeneous catalytic interface with dual-site synergy. This allows both to form corresponding active intermediates during plasma treatment. Subsequently, the two active intermediates combine to form alkanes. Therefore, this application can transform natural clay into a catalyst for plasma treatment, which can not only improve the conversion rate and product selectivity of carbon dioxide but also significantly reduce the catalyst production cost, providing a sustainable solution for high-value CO2 conversion.
[0007] In some embodiments, the first metal component satisfies one or two of the following conditions: the first metal component includes one or more of Fe, Co, and Ni; the mass percentage of the first metal component is 1%-15% based on the total mass of the catalyst; thereby, controlling the type of the first metal component within the aforementioned range can efficiently catalyze hydrogen cracking; controlling the mass percentage of the first metal component in the catalyst within the aforementioned range allows for the formation of appropriately dispersed catalytic active sites on the surface of the natural clay.
[0008] In some embodiments, the second metal component satisfies one or two of the following conditions: the second metal component includes one or more of Fe, Co, Cu, and Rh; and the mass percentage of the second metal component is 0.01%-0.5% based on the total mass of the catalyst. Therefore, controlling the type of the second metal component within the aforementioned range allows for efficient catalytic activation of carbon dioxide; controlling the mass percentage of the second metal component in the catalyst within the aforementioned range reduces the production cost of the catalyst while ensuring efficient catalytic activation of carbon dioxide.
[0009] In some embodiments, the natural clay includes one or more of kaolinite, montmorillonite, illite, palygorskite, sepiolite, serpentine, and chlorite. Thus, by controlling the type of natural clay within the aforementioned range, these natural clays not only contain active metal components such as iron, manganese, and cobalt, providing a partial source of active metals, but also have a price advantage, significantly reducing the production cost of natural clay-based catalysts.
[0010] In some embodiments, the plasma treatment method satisfies one or more of the following conditions: the output power of the plasma treatment method is 10W-40W; the discharge frequency of the plasma treatment method is 5kHz-25kHz; the reaction ambient temperature of the plasma treatment method is 60℃-100℃; the reactor pressure of the plasma treatment method is 0.05MPa-0.15MPa; the plasma treatment method includes introducing a mixed gas at a flow rate of 2mL / min-200mL / min; the residence time of the mixed gas in the discharge zone is 2s-6s; optionally, the mixed gas includes carbon dioxide and hydrogen, and the molar ratio of carbon dioxide to hydrogen is (0.2-0.5):1. Thus, by controlling the plasma treatment conditions within the aforementioned range, H2 cracking and CO2 activation can be simultaneously achieved, causing them to form corresponding active intermediates; subsequently, the two active intermediates combine to form alkanes.
[0011] In a second aspect, this application provides a catalyst comprising natural clay and an active metal located on the surface of the natural clay; the active metal comprises a first metal component for catalyzing hydrogen cracking and a second metal component for catalyzing carbon dioxide activation; wherein the mass ratio of the first metal component to the second metal component in the catalyst is 1:(0.01-0.5).
[0012] A third aspect of this application provides a method for preparing the catalyst of the second aspect of this application, comprising: adding the natural clay to an acid solution for acid treatment to obtain an acid-modified intermediate; adding the acid-modified intermediate to an alkaline solution for alkaline treatment to obtain a clay-based catalyst support; adding the clay-based catalyst support to an active metal salt solution to obtain a catalyst precursor; the active metal salt solution comprising a first metal salt and a second metal salt; calcining the catalyst precursor in a protective atmosphere to obtain the catalyst; wherein the mass ratio of the first metal component to the second metal component in the catalyst is 1:(0.01-0.5). Thus, acid treatment can appropriately remove inert components such as silica and alumina from the surface of the natural clay to expose the active metal sites in the natural clay, reducing their impact on the catalyst activation performance; alkaline treatment can regulate the pores of the layered clay, forming a porous support structure and increasing the specific surface area of the catalyst to 100 m². 2 The metal components are dispersed more efficiently and uniformly on the surface of natural clay to improve the efficiency of catalytic hydrogen cracking and carbon dioxide activation. Then, the metal salt is loaded onto the surface of the clay-based catalyst support. Finally, after calcination, the catalyst precursor can be converted into the catalyst required for plasma treatment. The mass ratio of the first metal component and the second metal component in the catalyst meets the aforementioned range.
[0013] In some embodiments, the acid treatment satisfies one or more of the following conditions: the acid solution includes one or more of hydrochloric acid, sulfuric acid, and nitric acid; the molar concentration of the acid solution is 0.5 mol / L to 5 mol / L; the temperature of the acid treatment is 50℃ to 100℃; and the time of the acid treatment is 1h to 24h.
[0014] In some embodiments, the alkali treatment satisfies one or more of the following conditions: the alkali solution includes one or both of sodium hydroxide and potassium hydroxide; the molar concentration of the alkali solution is 0.2 mol / L-5 mol / L; the temperature of the alkali treatment is 80℃-120℃; and the time of the alkali treatment is 2h-24h.
[0015] In some embodiments, the calcination treatment satisfies one or two of the following conditions: the calcination temperature is 200℃-700℃; the calcination time is 1h-12h; and the protective atmosphere includes one or more of nitrogen, argon, and hydrogen. Attached Figure Description
[0016] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the plasma reactor. Attached image description: 1. Shell; 2. Central electrode; 3. Catalytic converter; 4. Raw gas inlet. Detailed Implementation
[0018] Hereinafter, the specific embodiments disclosed will be described in detail with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of actually identical structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.
[0019] 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 also 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.
[0020] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.
[0021] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.
[0022] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).
[0023] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. "First feature" and "second feature" may include one or more of the indicated feature.
[0024] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.
[0025] Plasma treatment technology, as an energy and chemical process intensification technology, operates on the principle of inducing high-energy active species through discharge effects, thereby efficiently activating carbon dioxide molecules under mild atmospheric pressure and low reaction temperatures. Compared to other catalytic conversion pathways, such as photocatalysis, thermocatalysis, and electrocatalysis, plasma treatment technology can bypass the high-energy-consuming activation barriers of other catalytic pathways, promoting the directional conversion of carbon dioxide into the target product under mild reaction conditions.
[0026] In plasma treatment, catalysts can be combined with plasma-active species, effectively extending the lifetime of plasma-active species and increasing the probability of further activation and conversion of reaction intermediates. This facilitates the efficient generation of high-value-added products such as alkanes and methanol. Among related technologies, the preparation process of artificially synthesized catalysts is relatively complex and requires a large amount of reagents and energy. This not only increases the cost of carbon dioxide conversion but also causes additional carbon emissions, thus increasing the environmental burden.
[0027] Based on this, in its first aspect, this application provides a method for preparing alkanes using carbon dioxide. The methods include plasma treatment; plasma treatment includes the addition of a catalyst; The catalyst includes natural clay and an active metal located on the surface of the natural clay; the active metal includes a first metal component that catalyzes hydrogen cracking and a second metal component that catalyzes carbon dioxide activation; In the catalyst, the mass ratio of the first metal component to the second metal component is 1:(0.01-0.5).
[0028] In addition to silicon and aluminum oxides, natural clay itself contains active metal components such as iron, manganese, and cobalt, which can provide a partial source of active metals. Based on this, by further controlling the mass ratio of the first metal component to the second metal component in the catalyst within the aforementioned range, active metals that can strongly interact with H2 and CO2 are used as metal sites for catalytic H2 cracking and CO2 activation, respectively, serving as a heterogeneous catalytic interface with dual-site synergy. This allows both to form corresponding active intermediates during plasma treatment. Subsequently, the two active intermediates combine to form alkanes. Therefore, this application can transform natural clay into a catalyst for plasma treatment, which can not only improve the conversion rate and product selectivity of carbon dioxide but also significantly reduce the catalyst production cost, providing a sustainable solution for high-value CO2 conversion.
[0029] The mass ratio of the first metal component to the second metal component in the catalyst can be tested using methods such as atomic absorption spectroscopy, inductively coupled plasma atomic emission spectroscopy, and plasma mass spectrometry.
[0030] As an example, in the catalyst, the mass ratio of the first metal component to the second metal component can be 1:0.01, 1:0.05, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, or a range of any two of the above values.
[0031] In some embodiments, the natural clay includes one or more of kaolinite, montmorillonite, illite, palygorskite, sepiolite, serpentine, and chlorite.
[0032] Therefore, by controlling the types of natural clay within the aforementioned range, these natural clays not only contain active metal components such as iron, manganese, and cobalt, which can provide some sources of active metals, but also have a price advantage. As a result, the production cost of catalysts based on natural clay can be significantly reduced.
[0033] In some implementations, the alkane includes methane.
[0034] As an example, the technical solution of this application can efficiently convert carbon dioxide into methane, with the advantages of high conversion rate and high product selectivity.
[0035] In some embodiments, the first metal component includes one or more of Fe, Co, and Ni.
[0036] Therefore, by controlling the type of the first metal component within the aforementioned range, hydrogen cracking can be catalyzed efficiently.
[0037] In some implementations, the mass percentage of the first metal component is 1%-15% based on the total mass of the catalyst.
[0038] Therefore, by controlling the mass percentage of the first metal component in the catalyst within the aforementioned range, catalytic active sites with suitable dispersion are formed on the surface of the natural clay.
[0039] As an example, based on the total mass of the catalyst, the mass percentage of the first metal component can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc., or a range of any two of the above values.
[0040] In some embodiments, the second metal component includes one or more of Fe, Co, Cu, and Rh.
[0041] Therefore, by controlling the type of the second metal component within the aforementioned range, carbon dioxide activation can be catalyzed efficiently.
[0042] By loading two or more active metals onto the surface of natural clay, the competitive effect of different reactions such as hydrogen cracking and carbon dioxide activation at the same site is reduced, thereby enhancing catalytic efficiency.
[0043] In some implementations, the mass percentage of the second metal component is 0.01%-0.5% based on the total mass of the catalyst.
[0044] Therefore, by controlling the mass ratio of the second metal component in the catalyst within the aforementioned range, the production cost of the catalyst can be reduced while achieving efficient catalysis of carbon dioxide activation.
[0045] As an example, based on the total mass of the catalyst, the mass percentage of the second metal component can be 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc., or a range of any two of the above values.
[0046] In some implementations, the plasma treatment process occurs in a plasma reactor.
[0047] As an example, such as Figure 1As shown, a cylindrical single-medium barrier reactor can be used for the plasma-catalyzed hydrogenation of carbon dioxide to produce alkanes. Specifically, the reactor includes a cylinder 1, which can be a quartz cylindrical cylinder. The upper end of the cylinder 1 is an upper end cap with a central hole. Figure 1 (Not shown in the image) A 2mm diameter central electrode 2 is inserted into the central hole of the upper end cap along the central axis of the cylinder 1. The central electrode 2 is a stainless steel rod; the top of the central electrode 2 is connected to a plasma power source. A catalytic device 3 is installed in the cylinder 1 at the position of the central electrode 2. The catalytic device 3 includes the catalyst prepared in this application. A raw material gas inlet 4 is provided at the upper end of the side wall of the cylinder 1 (the raw material gas introduced is a mixture of carbon dioxide and hydrogen). Figure 1 In the diagram, the arrow indicates the direction of the raw gas intake; the lower end of cylinder 1 is equipped with a collection device and a tail gas outlet. Figure 1 (Not shown in the image).
[0048] During the operation of the plasma reactor, raw material gas is first introduced through the raw material inlet 4 for a period of time to purge the air inside the reactor; then the plasma power supply is turned on, and the raw material gas is efficiently cracked and activated at the catalytic device 3 to form alkanes.
[0049] In some implementations, the plasma treatment method satisfies one or more of the following conditions: The output power of plasma treatment is 10W-40W; The discharge frequency of the plasma treatment method is 5kHz-25kHz; The reaction environment temperature for plasma treatment is 60℃-100℃; The reactor pressure for plasma treatment is 0.05 MPa-0.15 MPa; The plasma treatment method includes introducing a mixed gas with a flow rate of 2 mL / min to 200 mL / min and a residence time of 2 s to 6 s in the discharge zone.
[0050] Furthermore, the mixture includes carbon dioxide and hydrogen, with a molar ratio of carbon dioxide to hydrogen of (0.2-0.5):1.
[0051] Therefore, by controlling the plasma treatment conditions within the aforementioned range, H2 cracking and CO2 activation can be achieved simultaneously, causing each to form a corresponding active intermediate; subsequently, the two active intermediates combine to form alkanes.
[0052] As an example, the output power of the plasma treatment method can be 10W, 15W, 20W, 25W, 30W, 35W, 40W, etc., or a range of any two of the above values.
[0053] As an example, the discharge frequency of the plasma treatment method can be 5kHz, 6kHz, 7kHz, 8kHz, 9kHz, 10kHz, 11kHz, 12kHz, 13kHz, 14kHz, 15kHz, 16kHz, 17kHz, 18kHz, 19kHz, 20kHz, 21kHz, 22kHz, 23kHz, 24kHz, 25kHz, etc., or a range of any two of the above values.
[0054] As an example, the reaction environment temperature of the plasma treatment method can be 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, etc., or a range consisting of any two of the above values.
[0055] As an example, the reactor pressure for plasma treatment can be 0.05 MPa, 0.06 MPa, 0.07 MPa, 0.08 MPa, 0.09 MPa, 0.1 MPa, 0.11 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa, 0.15 MPa, or a range of any two of the above values.
[0056] As an example, the gas flow rate of the mixed gas can be 2 mL / min, 20 mL / min, 40 mL / min, 60 mL / min, 80 mL / min, 100 mL / min, 120 mL / min, 140 mL / min, 160 mL / min, 180 mL / min, 200 mL / min, etc., or a range consisting of any two of the above values.
[0057] As an example, the residence time of the gas mixture in the discharge zone can be 2s, 2.5s, 3s, 3.5s, 4s, 4.5s, 5s, 5.5s, 6s, or a range of any two of the above values.
[0058] As an example, the molar ratio of carbon dioxide to hydrogen can be 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, or a range of any two of the above values.
[0059] In a second aspect, this application provides a catalyst comprising natural clay and an active metal located on the surface of the natural clay; the active metal comprises a first metal component for catalyzing hydrogen cracking and a second metal component for catalyzing carbon dioxide activation; wherein the mass ratio of the first metal component to the second metal component in the catalyst is 1:(0.01-0.5).
[0060] In a third aspect, this application provides a method for preparing the catalyst of the first aspect, specifically, the steps for preparing the catalyst include: S100. Natural clay is added to an acid solution for acid treatment to obtain an acid-modified intermediate. Therefore, acid treatment can appropriately remove inert components such as silica and alumina from the surface of natural clay, thereby exposing the active metal sites in the natural clay and reducing the impact on the activation performance of the catalyst.
[0061] In some embodiments, the acid solution includes one or more of hydrochloric acid, sulfuric acid, and nitric acid.
[0062] Therefore, by controlling the type of acid solution within the aforementioned range, inert components such as silica and alumina on the surface of natural clay can be appropriately removed to expose the active metal sites in the natural clay.
[0063] In some embodiments, the molar concentration of the acid solution is 0.5 mol / L to 5 mol / L.
[0064] Therefore, by controlling the concentration of the acid solution within the aforementioned range, and under the premise of appropriately removing inert components such as silica and alumina from the surface of natural clay, excessive damage to the structure of natural clay can be reduced.
[0065] As an example, the molar concentration of the acid solution can be 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, or a range of any two of the above values.
[0066] In some implementations, the acid-modified intermediate needs to be washed with water to neutralize its pH.
[0067] In some embodiments, the acid treatment temperature is 50°C-100°C, and the acid treatment time is 1h-24h.
[0068] Therefore, controlling the temperature and time of acid treatment within the aforementioned range can not only improve the efficiency of removing inert components from the surface of natural clay, but also reduce excessive damage to the structure of natural clay.
[0069] As an example, the acid treatment temperature can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, or a range of any two of the above values.
[0070] As an example, the acid treatment time can be 1h, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, or a range of any two of the above values.
[0071] S200. The acid-modified intermediate is added to an alkaline solution for alkaline treatment to obtain a clay-based catalyst support.
[0072] Therefore, alkali treatment can regulate the pores of layered clay, forming a porous support structure and increasing the specific surface area of the catalyst to 100 m². 2 / g or more, thereby enabling the metal components to be more efficiently and uniformly dispersed on the surface of natural clay, so as to improve the efficiency of catalytic hydrogen cracking and carbon dioxide activation.
[0073] In some embodiments, the alkaline solution includes one or both of sodium hydroxide and potassium hydroxide. Therefore, by controlling the type of alkaline solution within the aforementioned range, the pore size of the layered clay can be controlled, forming a porous support structure and increasing the specific surface area of the catalyst to 100 m². 2 / g or more, thereby enabling the metal components to be more efficiently and uniformly dispersed on the surface of natural clay, so as to improve the efficiency of catalytic hydrogen cracking and carbon dioxide activation.
[0074] In some embodiments, the molar concentration of the alkaline solution is 0.2 mol / L to 5 mol / L. Therefore, by controlling the molar concentration of the alkaline solution within the aforementioned range, excessive damage to the natural clay structure is reduced while appropriately improving the catalyst's pore structure.
[0075] As an example, the molar concentration of the alkaline solution can be 0.2 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L, 5 mol / L, or a range of any two of the above values.
[0076] In some embodiments, the alkali treatment temperature is 80℃-120℃, and the alkali treatment time is 2h-24h.
[0077] Therefore, controlling the temperature and time of alkali treatment within the aforementioned range can not only increase the pore-forming rate but also reduce excessive damage to the natural clay structure.
[0078] As an example, the temperature for alkali treatment can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, etc., or a range consisting of any two of the above values.
[0079] As an example, the alkali treatment time can be 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, or a range of any two of the above values.
[0080] S300. Add the clay-based catalyst support to the active metal salt solution to obtain the catalyst precursor; the active metal salt solution includes a first metal salt and a second metal salt.
[0081] Therefore, metal salts can be loaded onto the surface of clay-based catalyst supports.
[0082] In some embodiments, the active metal salt solution includes one or more of the following: chloride, nitrate, sulfate, and phosphate of the active metal.
[0083] As an example, the active metal salt solution may include one or more of Ni(NO3)2, Cu(NO3)2, Co(NO3)2, Fe(NO3)3, and RhCl3.
[0084] Therefore, the active metal salts within the aforementioned range can be dissolved in solvents, thereby enabling the metal salts to be loaded onto the surface of clay-based catalyst supports.
[0085] As an example, the solvent may include water.
[0086] Understandably, in the process of preparing catalysts, it is necessary to first detect the type and content of active metal components in natural clay, and then subtract the content of active metal components in natural clay itself from the required active metal loading to determine the concentration of additional active metal salts to be added.
[0087] S400, the catalyst precursor is calcined in a protective atmosphere to obtain the catalyst; in the catalyst, the mass ratio of the first metal component to the second metal component is 1:(0.01-0.5).
[0088] Therefore, through calcination, the catalyst precursor can be converted into the catalyst required for plasma treatment, and the mass ratio of the first metal component and the second metal component in the catalyst meets the aforementioned range.
[0089] In some embodiments, the calcination temperature is 200℃-700℃; the calcination time is 1h-12h.
[0090] Therefore, by controlling the temperature and time of calcination within the aforementioned range, production costs can be saved while improving calcination efficiency.
[0091] As an example, the calcination temperature can be 200℃, 250℃, 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, etc., or a range consisting of any two of the above values.
[0092] As an example, the calcination time can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, or a range of any two of the above values.
[0093] In some embodiments, the protective atmosphere includes one or more of nitrogen, argon, and hydrogen.
[0094] Therefore, by controlling the type of protective atmosphere within the aforementioned range, oxygen or water vapor in the air can be prevented from entering the reaction system, thereby improving the efficiency of calcination treatment.
[0095] Example The following specific embodiments illustrate the solution of this application. It should be noted that these embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.
[0096] Example 1 (1) Preparation of the catalyst, including the following steps: S100. Take 5g of natural kaolinite, disperse the natural kaolinite in 100mL of H2SO4 solution with a molar concentration of 1mol / L, reflux at 90℃ for 2h, filter and wash with water until the pH is close to neutral, and dry in an oven at 100℃ to obtain the acid-modified intermediate. S200, take 2g of acid-modified intermediate and disperse it in 50mL of NaOH solution with a molar concentration of 2mol / L. After hydrothermal reaction at 100℃ for 8h, filter and wash with water until the pH is close to neutral, and dry in an oven at 100℃ to obtain kaolinite-based catalyst support. S300: Dissolve 0.52g of Ni(NO3)2·6H2O and 0.2g of RhCl3·nH2O (wherein RhCl3·nH2O contains 38.5% Rh by mass) in deionized water to obtain an active metal salt solution; add 1g of the kaolinite-based catalyst support prepared in step S100 to the active metal salt solution, stir at room temperature for 2h, let stand for 24h, and then dry in an oven at 70℃ overnight to obtain the catalyst precursor; S400. The catalyst precursor is placed in a tube furnace and calcined at 500°C for 2 hours in a mixed atmosphere of Ar and H2 to obtain the catalyst.
[0097] Based on the total mass of the catalyst, the mass percentage of Ni component is 10%, and the mass percentage of Rh component is 0.1%; the mass ratio of Ni component to Rh component in the catalyst is 1:0.01.
[0098] (2) A method for preparing methane using carbon dioxide, comprising the following steps: The 0.1g catalyst prepared above was placed in the catalytic device of the plasma reactor. Before plasma treatment, a mixture of carbon dioxide and hydrogen was introduced into the reactor. The molar ratio of carbon dioxide to hydrogen in the mixture was 0.25:1, and the gas flow rate of the mixture was 50mL / min.
[0099] During the catalytic plasma reaction, the output power is 36W, the discharge frequency is 5kHz, the reaction environment temperature is 60℃-70℃, and the reactor pressure is 0.1MPa; the residence time of the mixed gas in the discharge zone is 3.75s. Thus, the feed gas is efficiently cracked and activated at catalytic unit 3 to form methane.
[0100] Comparative Examples 1-5 The difference between Comparative Example 1 and Example 1 is that no catalyst is added during the plasma treatment process.
[0101] The difference between Comparative Example 2 and Example 1 is that the catalyst is only a Ni-supported kaolinite-based catalyst support.
[0102] The difference between Comparative Example 3 and Example 1 is that the catalyst is only a Rh-supported kaolinite-based catalyst support.
[0103] The difference between Comparative Example 4 and Example 1 is that the mass ratio of Ni component to Rh component in the catalyst is 1:0.005.
[0104] The difference between Comparative Example 5 and Example 1 is that the mass ratio of Ni component to Rh component in the catalyst is 1:0.8.
[0105] Examples 2-4 The difference between Example 2 and Example 1 is that the mass ratio of Ni component to Rh component in the catalyst is 1:0.01.
[0106] The difference between Example 3 and Example 1 is that the mass ratio of Ni component to Rh component in the catalyst is 1:0.05.
[0107] The difference between Example 4 and Example 1 is that the mass ratio of Ni component to Rh component in the catalyst is 1:0.5.
[0108] Performance testing: The products obtained during the plasma processing of the examples and comparative examples were analyzed by gas chromatography, which combines a thermal conductivity cell and a flame ionization detector, to detect the gases emitted from the catalytic reaction in the examples and comparative examples, and the conversion rate and selectivity of the catalyst were calculated.
[0109] The test results of Examples 1-4 and Comparative Examples 1-5 are shown in Table 1.
[0110] Table 1
[0111] As shown in Table 1, the catalyst used in this application can convert natural clay into a catalyst for plasma treatment. The catalyst is loaded with an active metal that can strongly interact with H2 and CO2. As a heterogeneous catalytic interface with dual-site synergy, it can not only improve the conversion rate of carbon dioxide and the selectivity of products, but also significantly reduce the production cost of the catalyst.
[0112] Meanwhile, by controlling the mass ratio of Ni to Rh elements in the catalyst within the aforementioned range, active metals that can strongly interact with H2 and CO2 are used as metal sites for catalytic H2 cracking and CO2 activation, respectively, serving as a heterogeneous catalytic interface with dual-site synergy, so that the two can form corresponding active intermediates. Subsequently, the two active intermediates combine to form methane, exhibiting high carbon dioxide conversion rate and methane selectivity.
[0113] In Comparative Examples 4 and 5, if the mass ratio of Ni to Rh is too large or too small, it is difficult to form an efficient heterogeneous catalytic interface, resulting in poor carbon dioxide conversion or methane selectivity.
[0114] Comparative Examples 6-8 The difference between Comparative Example 6 and Example 1 is that the natural kaolinite was not treated with acid or alkali.
[0115] The difference between Comparative Example 7 and Example 1 is that the kaolinite was only acid-treated and not subjected to alkaline heat treatment.
[0116] The difference between Comparative Example 8 and Example 1 is that the kaolinite was only treated with alkali and not with acid.
[0117] The test results of Comparative Examples 6-8 are shown in Table 2.
[0118] Table 2
[0119] As shown in Table 2, without acid or alkali treatment, it is difficult for natural kaolinite to efficiently and uniformly load Ni and Ru components on its surface, resulting in difficulty in forming a heterogeneous catalytic interface with dual-site synergy, and poor carbon dioxide conversion and methane selectivity.
[0120] Examples 5-6 The difference between Example 5 and Example 1 is that the natural kaolinite is loaded with Ni and Cu elements. Based on the total mass of the catalyst, the mass ratio of Ni element is 10% and the mass ratio of Cu element is 0.5%.
[0121] The difference between Example 6 and Example 1 is that the natural kaolinite is loaded with Co and Rh elements. Based on the total mass of the catalyst, the mass ratio of Co is 10% and the mass ratio of Rh is 0.01%.
[0122] The test results of Examples 5-6 are shown in Table 3.
[0123] Table 3
[0124] As shown in Table 3, within the scope defined in this application, the types of metals loaded on the surface of natural kaolin in the catalyst are controlled. Active metals that can interact strongly with H2 and CO2 are used as metal sites for catalytic H2 cracking and CO2 activation, respectively. As a heterogeneous catalytic interface with dual site synergy, the two metals form corresponding active intermediates. Then, the two active intermediates combine to form methane, which has a high carbon dioxide conversion rate and methane selectivity.
[0125] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.
Claims
1. A method for preparing alkanes using carbon dioxide, characterized in that, The method includes plasma treatment; the plasma treatment includes adding a catalyst. The catalyst comprises natural clay and an active metal located on the surface of the natural clay; the active metal comprises a first metal component that catalyzes hydrogen cracking and a second metal component that catalyzes carbon dioxide activation; In the catalyst, the mass ratio of the first metal component to the second metal component is 1:(0.01-0.5).
2. The method according to claim 1, characterized in that, The first metal component satisfies one or two of the following conditions: The first metal component includes one or more of Fe, Co, and Ni; Based on the total mass of the catalyst, the mass percentage of the first metal component is 1%-15%.
3. The method according to claim 1 or 2, characterized in that, The second metal component satisfies one or two of the following conditions: The second metal component includes one or more of Fe, Co, Cu, and Rh; Based on the total mass of the catalyst, the mass percentage of the second metal component is 0.01%-0.5%.
4. The method according to any one of claims 1-3, characterized in that, The natural clay includes one or more of the following: kaolinite, montmorillonite, illite, palygorskite, sepiolite, serpentine, and chlorite.
5. The method according to any one of claims 1-4, characterized in that, The plasma treatment method satisfies one or more of the following conditions: The output power of the plasma treatment method is 10W-40W; The discharge frequency of the plasma treatment method is 5kHz-25kHz; The reaction environment temperature for the plasma treatment method is 60℃-100℃; The reactor pressure for the plasma treatment method is 0.05 MPa-0.15 MPa; The plasma treatment method includes introducing a mixed gas at a flow rate of 2 mL / min to 200 mL / min; the residence time of the mixed gas in the discharge zone is 2 s to 6 s; optionally, the mixed gas includes carbon dioxide and hydrogen, and the molar ratio of carbon dioxide to hydrogen is (0.2-0.5):
1.
6. A catalyst, characterized in that, It includes natural clay and an active metal located on the surface of the natural clay; the active metal includes a first metal component that catalyzes hydrogen cracking and a second metal component that catalyzes carbon dioxide activation; In the catalyst, the mass ratio of the first metal component to the second metal component is 1:(0.01-0.5).
7. A method for preparing the catalyst according to claim 6, characterized in that, include: The natural clay was added to an acid solution for acid treatment to obtain an acid-modified intermediate. The acid-modified intermediate was added to an alkaline solution for alkaline treatment to obtain a clay-based catalyst support. The clay-based catalyst support is added to an active metal salt solution to obtain a catalyst precursor; The active metal salt solution includes a first metal salt and a second metal salt; The catalyst precursor is calcined in a protective atmosphere to obtain the catalyst; In the catalyst, the mass ratio of the first metal component to the second metal component is 1:(0.01-0.5).
8. The method according to claim 7, characterized in that, The acid treatment satisfies one or more of the following conditions: The acid solution includes one or more of hydrochloric acid, sulfuric acid, and nitric acid; The molar concentration of the acid solution is 0.5 mol / L to 5 mol / L; The acid treatment temperature is 50℃-100℃, and the acid treatment time is 1h-24h.
9. The method according to claim 7 or 8, characterized in that, The alkaline treatment satisfies one or more of the following conditions: The alkaline solution includes one or both of sodium hydroxide and potassium hydroxide; The molar concentration of the alkaline solution is 0.2 mol / L to 5 mol / L; The alkali treatment temperature is 80℃-120℃, and the alkali treatment time is 2h-24h.
10. The method according to any one of claims 7-9, characterized in that, The calcination treatment satisfies one or two of the following conditions: The calcination temperature is 200℃-700℃; the calcination time is 1h-12h. The protective atmosphere includes one or more of nitrogen, argon, and hydrogen.