Method and device for catalyzing dry reforming of methane through electrothermal coupling

Abstract

The invention discloses a method and a device for catalyzing methane dry reforming through electrothermal coupling. The method comprises the following steps of: directly electrifying the catalyst, heating the catalyst by using Joule heat, and directly contacting and colliding the reaction gas with the catalyst so as to drive the methane dry reforming reaction to be efficiently carried out on the surface of the catalyst. According to the method, deep cracking of methane is inhibited, activation and conversion of carbon dioxide are promoted, dynamic balance of deposition and elimination of deposited carbon is realized, and deactivation of deposited carbon of the catalyst is inhibited, so that the service life of the catalyst is prolonged, and the activity and stability of catalytic reaction are improved. The electrothermal coupling catalytic methane dry reforming technology can fully utilize renewable energy sources (such as solar energy and wind energy), the quick response characteristic of Joule heating can also realize high-efficiency starting and closing, and is suitable for intermittent energy supply, and these characteristics provide a reference scheme for future development of industrial production suitable for methane dry reforming.

Description

Technical Field

[0001] The invention belongs to the field of catalytic technology, and in particular relates to a method and a device for electrothermal coupled catalytic methane dry reforming. Background Art

[0002] Methane dry reforming is an effective method for converting two greenhouse gases, methane and carbon dioxide, into synthesis gas. This process not only helps to reduce greenhouse gas emissions, but also provides important raw gas for industry. However, there are two main problems in the methane dry reforming reaction process: easy carbon deposition and low conversion rate. The carbon deposition problem is one of the core difficulties in the industrial application of methane dry reforming technology. During the reaction process, carbon deposition on the surface of the catalyst will lead to the coverage of active sites or clogging of catalyst pores, which will lead to a decrease in catalyst activity or even loss of activity. Long-term carbon deposition can also easily clog pipelines and affect the normal operation of the reactor.

[0003] Secondly, low conversion rate is also an important factor limiting the development of methane dry reforming technology. Methane dry reforming is a highly endothermic process and usually needs to be carried out under high temperature conditions to obtain high yields. However, high temperature exacerbates the problem of carbon deposition, thereby affecting the activity and stability of the catalyst. Therefore, it is of great significance to develop catalysts with high activity, high stability and strong resistance to carbon deposition. Summary of the invention

[0004] In view of the above problems, the present invention proposes a method and device for electrothermal coupled catalytic methane dry reforming. The method introduces current and electric field while heating the catalyst, thereby suppressing the deep cracking of methane, promoting the activation and conversion of carbon dioxide, achieving a dynamic balance between the deposition and elimination of carbon deposits, suppressing the deactivation of the catalyst due to carbon deposits, thereby extending the service life of the catalyst, and at the same time improving the activity and stability of the catalytic reaction.

[0005] One of the technical solutions of the present invention is to provide a method for electrothermal coupled catalytic methane dry reforming, which uses an electrothermal treated catalyst to catalyze a mixed gas containing methane and carbon dioxide; the electrothermal treatment is: inputting current into the catalyst, and the catalyst is heated to 400°C-1200°C under the current.

[0006] Based on the Joule heating effect of the catalyst, the mixed gas containing methane and carbon dioxide is electrothermally coupled to achieve rapid heating of the catalyst and the near-surface reactant molecules, while also applying current and electric field to the catalyst; the reaction gas directly contacts and collides with the catalyst, thereby driving the methane dry reforming reaction efficiently on the catalyst surface. By applying an appropriate electric field, the breaking of the CH bond in the methane (CH4) molecule can be selectively promoted to prevent it from completely decomposing into carbon and hydrogen. This helps to reduce the formation of carbon deposits and maintain the activity of the catalyst surface. The presence of the electric field changes the adsorption mode of CO2 molecules on the catalyst surface, reducing the energy required for its activation, thereby more effectively converting CO2 into carbon monoxide (CO) and improving the overall reaction efficiency. In addition, certain types of catalyst materials will undergo changes in electronic structure under the action of the electric field, making it easier to interact with the reactants and accelerate the CO2 conversion process.

[0007] The introduced current can also accelerate the oxidation of carbon active intermediates and convert them into CO, thereby preventing the formation of carbon deposits and improving the stability of the catalyst. This method not only reduces the risk of catalyst deactivation, but also extends its service life and improves the activity and stability of the catalytic reaction. Through the above measures, the carbon deposition on the catalyst surface can be effectively inhibited, the catalyst deactivation problem caused by carbon deposition can be reduced, and the service life of the catalyst can be extended.

[0008] In summary, by applying an electric field on the catalyst surface, the reaction conditions of methane dry reforming can be optimized, the reaction efficiency and selectivity can be improved, and the formation of carbon deposits can be effectively inhibited to ensure the long-term stability of the catalyst performance.

[0009] Furthermore, the flow rate of the mixed gas is 40 mL / min.

[0010] Furthermore, the mixed gas is a mixed gas of methane, carbon dioxide and argon in a volume ratio of 1:1:2.

[0011] Furthermore, the catalyst is a conductive methane dry reforming catalyst, or a conductive material modified by a methane dry reforming catalyst.

[0012] Further, the conductive methane dry reforming catalyst is one or more of a noble metal methane dry reforming catalyst, a non-noble metal methane dry reforming catalyst, a metal carbide methane dry reforming catalyst and a carbon-based methane dry reforming catalyst.

[0013] The second technical solution of the present invention is to provide an electrothermal coupled catalytic methane dry reforming device, comprising: A reaction chamber for placing a catalyst; Positive and negative electrodes to supply electricity to the catalyst; An air inlet for inputting gas into the reaction chamber and an air outlet for outputting gas; A temperature measuring device for detecting the reaction temperature of the catalyst; And, a controller is used to adjust the input current of the positive and negative electrodes according to the temperature output by the temperature measuring device, so that the catalyst is heated to 400°C-1200°C under the current.

[0014] Furthermore, the reaction chamber is a tubular reaction chamber, which has good high temperature resistance and chemical stability.

[0015] Furthermore, the reaction chamber is transparent, and the temperature measuring device is an infrared temperature sensor located outside the chamber.

[0016] Furthermore, the air inlet and the air outlet are inserted into a metal air pipe, and the end of the metal air pipe is in contact with the catalyst in the reaction chamber to form the positive and negative electrodes.

[0017] The beneficial effects of the present invention are: when the temperature is 400°C, the conversion rate of CH4 and CO2 is increased by about 5 times compared with thermal catalysis; when the temperature is ≥500°C, the conversion rate of CH4 and CO2 is increased by at least 1.5 times compared with thermal catalysis; when the temperature is 1200°C, CH4 and CO2 can be completely converted. In the obtained synthesis gas, the H2 / CO ratio is close to 1, which is more conducive to the further application of the synthesis gas. Moreover, compared with thermal catalysis, it can effectively inhibit the carbon deposition of the catalyst and extend the service life of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of the device of the present invention, wherein 1 is a power supply, 2 is a controller, 3 is an electrode, 4 is a reaction chamber, 5 is a conductive catalyst, 6 is an electrode air inlet, 7 is an electrode air outlet, and 8 is a temperature measuring device; Figure 2 It is a temperature-methane conversion diagram of Example 1 and Comparative Example 1; Figure 3 Graph showing the carbon dioxide conversion rate of Example 1 and Comparative Example 1; Figure 4 Graph showing the ratio of hydrogen to carbon monoxide in Example 1 and Comparative Example 1; Figure 5 2 is a time-methane conversion diagram of Example 2 and Comparative Example 2. DETAILED DESCRIPTION

[0019] The reverse water gas reaction is a side reaction that requires special attention in the methane dry reforming process. Its chemical equation is: CO2+H2↔CO+H2O Under traditional thermal catalytic conditions, this process not only consumes hydrogen in the synthesis gas, reducing the efficiency of methane dry reforming and the selectivity of H2; but also the generated water will reduce the yield and purity of the synthesis gas. In order to improve the overall efficiency and product selectivity of methane dry reforming, it is very important to inhibit the reverse water gas reaction. By reducing unnecessary hydrogen consumption and avoiding the influence of water, the quality of the synthesis gas can be improved to make it more in line with the needs of downstream applications.

[0020] Therefore, in order to improve the efficiency of methane dry reforming, it is particularly important to control the occurrence of reverse water gas side reaction. Compared with the traditional thermal catalytic process, the electrothermal coupling technology proposed in the present invention can more effectively inhibit the reverse water gas reaction, thereby obtaining an ideal mixed gas with a hydrogen and carbon monoxide ratio closer to 1:1. Obtaining a synthesis gas with a H2 / CO ratio of 1 is more conducive to the further application of the synthesis gas. In certain chemical synthesis processes, such as Fischer-Tropsch synthesis or methanol synthesis, a specific H2 / CO ratio can improve the selectivity and yield of the target product. When the H2 / CO ratio is close to 1, it helps to optimize these reaction pathways, reduce the generation of by-products, and thus improve the overall efficiency.

[0021] Those skilled in the art can adjust the current according to actual needs to achieve heating to 400° C.-1200° C.

[0022] The following examples are used to further illustrate the present invention, and their purpose is to illustrate the present invention and should not be construed as limiting the scope of the present invention. Unless otherwise specified, all parts by weight and weight percentages are used below.

[0023] The raw materials used in the present invention, unless otherwise specified, are conventional commercially available products; the methods used in the present invention, unless otherwise specified, are conventional methods in the art.

[0024] The embodiments of the present invention are further described below with reference to a plurality of embodiments.

[0025] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0026] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0027] Figure 1 An example of a device for realizing the electrothermal coupled catalytic methane dry reforming of the present invention includes: A reaction chamber 4 containing a catalyst; Positive and negative electrodes 3 for supplying electricity to the catalyst; An air inlet 6 for inputting gas into the reaction chamber and an air outlet 7 for outputting gas; A temperature measuring device 8 for detecting the reaction temperature of the catalyst; And, a controller 2 is used to adjust the input current of the positive and negative electrodes according to the temperature output by the temperature measuring device, so that the catalyst is heated to 400°C-1200°C under the current.

[0028] In the figure, it is inserted into the air inlet 6 and the air outlet 7, the copper tube and the catalyst edge are in contact and conductive, and the gas comes into contact with the catalyst after coming out of the copper tube.

[0029] In the figure, the reaction chamber is a tubular reaction chamber, the reaction chamber is transparent, and the temperature measuring device is an infrared temperature sensor located outside the chamber.

[0030] Example 1 (1) Nickel foam is used as a catalyst, the catalyst is placed in a reaction chamber, and both ends of the catalyst are in direct contact with the conductive electrode.

[0031] (2) First, high-purity argon gas is introduced from the gas inlet of the container for a period of time to prevent the impurity gas in the reactor from affecting the methane dry reforming reaction.

[0032] (3) The corresponding mixed gas ratio is methane: carbon dioxide: argon = 1:1:2, and the flow rate of the mixed gas is 40 mL / min. The mixed gas enters the reaction chamber from the gas inlet and flows through the catalyst; at the same time, an electric current is applied to the electrodes of the reactor, and the current flows through the catalyst to generate an electric field and Joule heat, thereby performing electrothermal coupled catalytic methane dry reforming, and the reactions are carried out at 500°C, 600°C, 700°C and 800°C, respectively.

[0033] (4) The synthesis gas prepared by the reaction at 500°C, 600°C, 700°C and 800°C was collected through the gas outlet, and the reaction conversion rate and the ratio of hydrogen to carbon monoxide were analyzed by gas chromatography.

[0034] Comparative Example 1 A foamed nickel catalyst of the same size as that in the embodiment was placed in a conventional thermal catalytic device for methane dry reforming.

[0035] Steps (2) to (5) are the same as those in Example 1.

[0036] Depend on Figure 2 and Figure 3The evaluation results of the methane dry reforming catalysts of Example 1 and Comparative Example 1 show that the electrothermal coupled catalytic methane dry reforming of the present invention has better catalytic performance than thermal catalytic methane dry reforming. The conversion rates of CH4 and CO2 when using this scheme are greater than those when using thermal catalysis, and the conversion rates are at least increased by 2 times. Figure 4 From the H2 / CO ratio shown, it can be seen that the H2 / CO obtained by the electrothermal coupling scheme is closer to 1, indicating that the electrothermal coupling has a better effect in suppressing the reverse water gas side reaction.

[0037] Example 2 (1) A Ni / nickel foam is formed by impregnating nickel nitrate on nickel foam and then sintering it as a catalyst. The catalyst is placed in a reaction chamber, and both ends of the catalyst are in direct contact with a conductive electrode.

[0038] (2) First, high-purity argon gas is introduced from the gas inlet of the container for a period of time to prevent the impurity gas in the reactor from affecting the methane dry reforming reaction.

[0039] (3) The corresponding mixed gas ratio is methane: carbon dioxide: argon = 1:1:2, and the flow rate of the mixed gas is 40 mL / min. The mixed gas enters the reaction chamber from the gas inlet and flows through the catalyst; at the same time, an electric current is applied to the electrodes of the reactor. The current flows through the catalyst to generate an electric field and Joule heat, making the temperature in the reactor 800°C, thereby performing electrothermal coupled catalytic methane dry reforming.

[0040] (4) The prepared synthesis gas is collected through the gas outlet and the reaction conversion rate and the ratio of hydrogen to carbon monoxide are analyzed by gas chromatography.

[0041] Comparative Example 2 Ni / nickel foam is used as a catalyst and the catalyst is placed in a conventional thermal catalytic reaction device for methane dry reforming.

[0042] Steps (2) to (5) are the same as those in Example 2.

[0043] Depend on Figure 5 The evaluation results of the methane dry reforming catalysts of Example 2 and Comparative Example 2 show that, compared with the thermal catalytic methane dry reforming, the catalyst of the electrothermal coupled catalytic scheme of the present invention can be stably operated for at least 100 hours, while the same catalyst is deactivated in 3.5 hours under the thermal catalytic mode. It can be seen that the electrothermal coupling has a very significant anti-carbon deposition effect and greatly improves the stability of the catalyst.

[0044] Example 3 (1) Impregnation of nickel foam with holmium nitrate followed by sintering to form HoO x / Foamed nickel catalyst, the catalyst is placed in the reaction chamber, and both ends of the catalyst are in direct contact with the conductive electrodes.

[0045] (2) First, high-purity argon gas is introduced from the gas inlet of the container for a period of time to prevent the impurity gas in the reactor from affecting the methane dry reforming reaction.

[0046] (3) The corresponding mixed gas ratio is methane: carbon dioxide: argon = 1:1:2, and the flow rate of the mixed gas is 40 mL / min. The mixed gas enters the reaction chamber from the gas inlet and flows through the catalyst; at the same time, an electric current is applied to the electrodes of the reactor. The current flows through the catalyst to generate an electric field and Joule heat, making the temperature in the reactor 1200°C, thereby performing electrothermal coupled catalytic methane dry reforming.

[0047] (4) The prepared synthesis gas is collected through the gas outlet and the reaction conversion rate and the ratio of hydrogen to carbon monoxide are analyzed by gas chromatography.

[0048] Comparative Example 3 The same HoO as in the embodiment is used. x / Foamed nickel catalyst is placed in a conventional thermal catalytic device for methane dry reforming.

[0049] Steps (2) to (5) are the same as those in Example 3.

[0050] According to the results, the electrothermal coupling CH4 conversion rate is 100%, the CO2 conversion rate is 100%, and H2 / CO=1; the thermal catalytic CH4 conversion rate is 62%, and the CO2 conversion rate is 71%. H2 / CO=0.72. It can be seen that under this catalytic condition, the electrothermal coupling conversion rate is about 1.6 times that of thermal catalysis, and the reverse water gas side reaction can be suppressed to obtain an ideal synthesis gas with H2 / CO of 1.

[0051] Example 4 (1) Impregnation of cerium nitrate and nickel nitrate on titanium foam and sintering to form Ni@CeO x / Foam titanium catalyst, the catalyst is placed in the reaction chamber, and both ends of the catalyst are in direct contact with the conductive electrodes.

[0052] (2) First, high-purity argon gas is introduced from the gas inlet of the container for a period of time to prevent the impurity gas in the reactor from affecting the methane dry reforming reaction.

[0053] (3) The corresponding mixed gas ratio is methane: carbon dioxide: argon = 1:1:2, and the flow rate of the mixed gas is 40 mL / min. The mixed gas enters the reaction chamber from the gas inlet and flows through the catalyst; at the same time, an electric current is applied to the electrodes of the reactor. The current flows through the catalyst to generate an electric field and Joule heat, making the temperature in the reactor 400°C, thereby performing electrothermal coupled catalytic methane dry reforming.

[0054] (4) The prepared synthesis gas is collected through the gas outlet and the reaction conversion rate and the ratio of hydrogen to carbon monoxide are analyzed by gas chromatography.

[0055] Comparative Example 4 The same Ni@CeO x / The titanium foam catalyst is placed in a conventional thermal catalytic device for methane dry reforming.

[0056] Steps (2) to (5) are the same as those in Example 4.

[0057] According to the results, the electrothermal coupling CH4 conversion rate is 24%, CO2 conversion rate is 39%, H2 / CO=0.68; the thermal catalytic CH4 conversion rate is 5%, CO2 conversion rate is 14%, H2 / CO=0.3. It can be seen that under this catalytic condition, the electrothermal coupling conversion rate is about 5 times that of thermal catalysis, and the reverse water gas side reaction can be suppressed to obtain a synthesis gas with a H2 / CO close to 1.

[0058] Example 5 (1) Cobalt nitrate is impregnated on nickel foam and then sintered to form Co@CeO x / Foamed nickel catalyst, the catalyst is placed in the reaction chamber, and both ends of the catalyst are in direct contact with the conductive electrodes.

[0059] (2) First, high-purity argon gas is introduced from the gas inlet of the container for a period of time to prevent the impurity gas in the reactor from affecting the methane dry reforming reaction.

[0060] (3) The corresponding mixed gas ratio is methane: carbon dioxide: argon = 1:1:2, and the flow rate of the mixed gas is 40 mL / min. The mixed gas enters the reaction chamber from the gas inlet and flows through the catalyst; at the same time, an electric current is applied to the electrodes of the reactor. The current flows through the catalyst to generate an electric field and Joule heat, making the temperature in the reactor 700°C, thereby performing electrothermal coupled catalytic methane dry reforming.

[0061] (4) The prepared synthesis gas is collected through the gas outlet and the reaction conversion rate and the ratio of hydrogen to carbon monoxide are analyzed by gas chromatography.

[0062] Comparative Example 5 The same Co@CeO x / Foamed nickel catalyst is placed in a conventional thermal catalytic device for methane dry reforming.

[0063] Steps (2) to (5) are the same as those in Example 4.

[0064] According to the results, the electrothermal coupling CH4 conversion rate is 81%, CO2 conversion rate is 83%, H2 / CO=0.98; the thermal catalytic CH4 conversion rate is 52%, CO2 conversion rate is 64%, H2 / CO=0.61. It can be seen that under this catalytic condition, the electrothermal coupling conversion rate is about 1.5 times that of thermal catalysis, and it can suppress the reverse water gas side reaction to obtain a synthesis gas with H2 / CO close to 1.

[0065] The above embodiments describe in detail the structure, features and effects of the present invention. The above are only preferred embodiments of the present invention. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which do not exceed the scope covered by the specification, should be within the protection scope of the present invention.

Claims

1. A method for electrothermal coupled catalytic methane dry reforming, characterized in that: The mixed gas containing methane and carbon dioxide is catalyzed by using an electrothermal treated catalyst; the electrothermal treatment comprises: inputting electric current into the catalyst, and heating the catalyst to 400°C-1200°C under the electric current.

2. The method according to claim 1, characterized in that The flow rate of the mixed gas is 40 mL / min.

3. The method according to claim 1, characterized in that The mixed gas is a mixed gas of methane, carbon dioxide and argon in a volume ratio of 1:1:

2.

4. The method according to claim 1, characterized in that: The catalyst is a conductive methane dry reforming catalyst, or a conductive material modified by a methane dry reforming catalyst.

5. The method according to claim 4, characterized in that The conductive methane dry reforming catalyst is one or more of a noble metal methane dry reforming catalyst, a non-noble metal methane dry reforming catalyst, a metal carbide methane dry reforming catalyst and a carbon-based methane dry reforming catalyst.

6. An electrothermal coupled catalytic methane dry reforming device, characterized in that: include: A reaction chamber containing a catalyst; Positive and negative electrodes to supply electricity to the catalyst; An air inlet for inputting gas into the reaction chamber and an air outlet for outputting gas; A temperature measuring device for detecting the reaction temperature of the catalyst; And, a controller is used to adjust the input current of the positive and negative electrodes according to the temperature output by the temperature measuring device, so that the catalyst is heated to 400°C-1200°C under the current.

7. The device according to claim 6, characterized in that The reaction chamber is a tubular reaction chamber.

8. The device according to claim 6, characterized in that The reaction chamber is transparent, and the temperature measuring device is an infrared temperature sensor located outside the chamber.

9. The device according to claim 6, characterized in that The air inlet and the air outlet are inserted into a metal air pipe, and the end of the metal air pipe contacts the catalyst in the reaction chamber to form the positive and negative electrodes.

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