Catalyst for catalyzing reverse water gas shift of carbon dioxide, and preparation method and application thereof

Abstract

The present application provides a kind of catalyst for catalyzing carbon dioxide reverse water gas shift and its preparation method and application, the catalyst for catalyzing carbon dioxide reverse water gas shift includes carbon nanotube containing nickel element and copper element supported on the carbon nanotube.The catalyst for catalyzing carbon dioxide reverse water gas shift provided by the present application uses carbon nanotube containing nickel element as carrier, copper and nickel as active metal, and the synergistic effect can improve the catalytic activity of catalyst, so that the catalyst can improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide when catalyzing carbon dioxide to generate carbon monoxide in reverse water gas reaction.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of materials, and particularly relates to a catalyst for catalyzing carbon dioxide reverse water gas shift reaction, and a preparation method and application thereof. BACKGROUND

[0002] The reverse water gas shift reaction (RWGS) provides an effective way to convert carbon dioxide (CO2) into active carbon platform compound carbon monoxide (CO) as a reverse process of the water gas shift reaction. Through further chemical reactions, the generated CO can be synthesized into high-value-added products such as liquid fuels, alcohols, aldehydes, acids and olefins. In recent years, with the rapid development of renewable energy such as wind and solar energy, the coupling of hydrogen produced by electrolysis of water and the reverse water gas shift reaction of CO2 has become a new route to realize carbon emission reduction and co-production of high-value-added chemicals.

[0003] However, the chemical inertness and stability of CO2 make its conversion challenging, especially the activation of the C=O bond. The reaction enthalpy ΔH of the RWGS reaction is 42.1 KJ / mol, which is a typical endothermic reaction. High temperature is conducive to the forward reaction, but it also means that the RWGS reaction is a high-energy process. Under high temperature conditions (>700℃), the catalyst is prone to sintering or carbon deposition, resulting in deactivation, which leads to low carbon dioxide conversion and low carbon monoxide selectivity in the reverse water gas reaction. SUMMARY

[0004] The main purpose of the present application is to provide a catalyst for catalyzing carbon dioxide reverse water gas shift reaction, which can improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide when used in reverse water gas reaction.

[0005] The present application also provides a preparation method of a catalyst for catalyzing carbon dioxide reverse water gas shift reaction, which can prepare the above-mentioned catalyst for catalyzing carbon dioxide reverse water gas shift reaction, and the process is simple and the cost is low.

[0006] The present application also provides a preparation method of carbon monoxide, which uses the above-mentioned catalyst to catalyze carbon dioxide reverse water gas reaction, which can improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0007] In the first aspect, the present application provides a catalyst for catalyzing carbon dioxide reverse water gas shift reaction, which comprises carbon nanotubes containing nickel elements and copper elements loaded on the carbon nanotubes.

[0008] The catalyst for catalyzing carbon dioxide reverse water gas shift reaction as described above comprises 2%-6% copper elements, 2%-4% nickel elements, and the balance is carbon nanotubes in terms of mass percentage.

[0009] The catalyst for catalyzing carbon dioxide reverse water gas shift as described above comprises, in percentage by mass, 4%-6% of copper element, 2%-3% of nickel element, and the balance of carbon nanotubes.

[0010] The catalyst for catalyzing carbon dioxide reverse water gas shift as described above is prepared by a method comprising the following process:

[0011] The raw material system comprising a nickel source and a carbon source is subjected to heat treatment, the carbon nanotubes containing nickel element obtained is subjected to activation treatment, and the activated intermediate obtained by the activation treatment is subjected to impregnation treatment by using a solution comprising a copper source, thereby obtaining the catalyst for catalyzing carbon dioxide reverse water gas shift.

[0012] In the second aspect, the application provides a preparation method of the catalyst for catalyzing carbon dioxide reverse water gas shift as described above, comprising the following steps:

[0013] 1) The raw material system comprising a nickel source and a carbon source is subjected to heat treatment under a reducing atmosphere, thereby obtaining carbon nanotubes containing nickel element;

[0014] 2) The carbon nanotubes containing nickel element obtained is subjected to activation treatment, thereby obtaining an activated intermediate;

[0015] 3) The activated intermediate is subjected to impregnation treatment by using a solution comprising a copper source, thereby obtaining the catalyst for catalyzing carbon dioxide reverse water gas shift.

[0016] The preparation method of the catalyst for catalyzing carbon dioxide reverse water gas shift as described above, wherein the temperature of the heat treatment is 700-800°C, and the time is 2-12h.

[0017] The preparation method of the catalyst for catalyzing carbon dioxide reverse water gas shift as described above, wherein the carbon nanotubes containing nickel element is subjected to activation treatment by using carbon dioxide;

[0018] The temperature of the activation treatment is 600-700°C, and the time is 1-2h;

[0019] And / or, the time of the impregnation treatment is 12-24h.

[0020] In the third aspect, the application provides a preparation method of carbon monoxide, comprising the following steps: catalyzing carbon dioxide to perform reverse water gas reaction by using the catalyst for catalyzing carbon dioxide reverse water gas shift as described above or the catalyst for catalyzing carbon dioxide reverse water gas shift prepared by the preparation method of the catalyst for catalyzing carbon dioxide reverse water gas shift as described above, thereby obtaining carbon monoxide.

[0021] The method for preparing carbon monoxide as described above comprises the following steps:

[0022] 1) activating the catalyst for catalytic reverse water gas shift of carbon dioxide by using hydrogen to obtain an activated catalyst;

[0023] 2) passing hydrogen and carbon dioxide into a fixed bed containing the activated catalyst to perform gas-solid contact at a temperature of 300-500 DEG C and a pressure of 0.15-0.2 MPa to perform the reverse water gas reaction to obtain the carbon monoxide.

[0024] The volume ratio of hydrogen to carbon dioxide in the method for preparing carbon monoxide as described above is (3-3.5):1.

[0025] The catalyst for catalytic reverse water gas shift of carbon dioxide provided by the application uses carbon nanotubes containing nickel elements as a carrier and copper and nickel as active metals, and the synergistic effect of the two can improve the catalytic activity of the catalyst, so that the catalyst can improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide when catalyzing carbon dioxide to perform the reverse water gas reaction to generate carbon monoxide. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0027] With the continuous increase in global dependence on fossil fuels, carbon dioxide (CO2) emissions have increased significantly, leading to intensified greenhouse effect and increasingly serious climate change. In order to cope with this challenge and achieve the goal of carbon neutrality, carbon dioxide capture and conversion technology has become a hot research topic. Among them, the reverse water gas shift reaction (RWGS) has attracted much attention due to its ability to convert carbon dioxide into carbon monoxide (CO). This reaction generates carbon monoxide and water (H2O) by reacting carbon dioxide with hydrogen (H2), and the generated carbon monoxide is an important component of synthesis gas, which can be further used to synthesize a variety of high-value chemicals and fuels, such as Fischer-Tropsch synthetic oil, low-carbon alcohols, olefins and aromatic hydrocarbons, etc.

[0028] However, despite the significant theoretical application potential of the reverse water gas shift reaction, it still faces many challenges in practical application. First, the conversion rate of carbon dioxide is low, which limits the overall efficiency of the reaction. Second, the selectivity of carbon monoxide is not high, leading to the generation of by-products, affecting the purity of the product and the economy of subsequent processing. In addition, the reverse water gas shift reaction usually needs to be carried out at high temperature, which not only increases the energy consumption, but also puts higher requirements on the stability and service life of the catalyst. Therefore, developing an efficient and stable catalyst system, improving the conversion rate of carbon dioxide and the selectivity of carbon monoxide, and reducing the reaction temperature are the key directions of the current reverse water gas shift reaction technology development. The inventors have found that by using carbon nanotubes as a catalyst carrier, the conversion rate of carbon dioxide and the selectivity of carbon monoxide in the reverse water gas shift reaction can be significantly improved.

[0029] Based on this, in a first aspect, the present application provides a catalyst for catalyzing the reverse water gas shift of carbon dioxide, comprising carbon nanotubes containing nickel elements and copper elements supported on the carbon nanotubes. Wherein the nickel elements are grown in situ on the carbon nanotubes.

[0030] The catalyst provided by the present application comprises carbon nanotubes containing nickel elements and copper elements supported on the carbon nanotubes, which can improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide in the reverse water gas shift reaction when catalyzing the reverse water gas shift of carbon dioxide to obtain carbon monoxide. This is because, on the one hand, carbon nanotubes can provide a higher specific surface area, which is conducive to increasing the dispersion of active metals and exposing more active sites to the reaction environment, thereby improving the catalytic activity. On the other hand, the electrical conductivity of carbon nanotubes is conducive to improving the electron transfer efficiency, promoting the activation of reactants and the reaction rate. In addition, the high thermal stability of carbon nanotubes enables them to maintain structural integrity under high-temperature reaction conditions, prolonging the service life of the catalyst. Nickel in the active metal can promote the activation of carbon dioxide and the dissociation of hydrogen; copper has high selectivity and can inhibit the occurrence of side reactions, thereby improving the selectivity of carbon monoxide. The strong interaction between carbon nanotubes and active metals can prevent the aggregation and sintering of metal particles, maintain the activity and stability of the catalyst, and the combination of nickel and copper can reduce the formation of carbon deposition, maintaining the long-term stable operation of the catalyst.

[0031] Therefore, the catalyst for catalyzing the reverse water gas shift of carbon dioxide provided by the present application uses carbon nanotubes containing nickel elements as a carrier and copper and nickel as active metals, and their synergistic effect can improve the catalytic activity of the catalyst, so that the catalyst can improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide when catalyzing the reverse water gas shift of carbon dioxide to generate carbon monoxide.

[0032] In some embodiments of the present application, the catalyst for catalyzing the reverse water gas shift reaction of carbon dioxide comprises, by mass percentage, 2%-6% of copper element, 2%-4% of nickel element, and the balance of carbon nanotubes.

[0033] For example, the mass percentage of copper element can be 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, or a range formed by any two of them; the mass percentage of nickel element can be 2%, 2.5%, 3%, 3.5%, 4%, or a range formed by any two of them.

[0034] In the above catalyst, the content of copper element is conducive to improving the selectivity of carbon monoxide and inhibiting the occurrence of side reactions, and can exhibit good catalytic activity at a lower temperature. The content of nickel element can promote the activation of carbon dioxide and the dissociation of hydrogen, improve the reaction rate and the conversion rate of carbon dioxide. In addition, the addition of nickel element is also conducive to improving the stability and carbon deposition resistance of the catalyst, prolonging the service life of the catalyst. The carbon nanotubes can provide a large number of active sites, support the high dispersibility of metal particles, enhance the overall catalytic activity, improve the electron transfer efficiency, and improve the stability of the catalyst under high temperature conditions.

[0035] In some embodiments of the present application, the catalyst for catalyzing the reverse water gas shift reaction of carbon dioxide comprises, by mass percentage, 4%-6% of copper element, 2%-3% of nickel element, and the balance of carbon nanotubes.

[0036] For example, the mass percentage of copper element can be 4%, 4.5%, 5%, 5.5%, 6%, or a range formed by any two of them; the mass percentage of nickel element can be 2%, 2.2%, 2.5%, 2.8%, 3%, or a range formed by any two of them.

[0037] As a preferred solution, the catalyst can further improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide when catalyzing the reverse water gas reaction of carbon dioxide to generate carbon monoxide.

[0038] In some embodiments of the present application, the catalyst for catalyzing the reverse water gas shift reaction of carbon dioxide is prepared by a method comprising the following processes:

[0039] The raw material system comprising a nickel source and a carbon source is subjected to heat treatment, the carbon nanotubes containing nickel element obtained are subjected to activation treatment, and the activated intermediate obtained by the activation treatment is subjected to impregnation treatment using a solution comprising a copper source, thereby obtaining the catalyst for catalyzing the reverse water gas shift reaction of carbon dioxide.

[0040] In one embodiment, the nickel source can be placed in a tube furnace, after the nitrogen gas is introduced to replace the air sufficiently, the reducing gas is introduced, heated to a certain temperature, then the carbon source is introduced, after a certain time of reaction, nitrogen gas is introduced again, and the temperature is lowered to room temperature under the nitrogen atmosphere, to obtain carbon nanotubes containing nickel elements (Ni-CNT). Then the carbon nanotubes containing nickel elements are placed in a tube furnace, after the nitrogen gas is introduced to replace the air sufficiently, heated to a certain temperature, then the carbon dioxide is introduced for activation treatment, after a certain time of reaction, nitrogen gas is introduced again, and the temperature is lowered to room temperature under the nitrogen atmosphere, to obtain activated Ni-CNT. The copper source is dissolved in deionized water to form a copper source solution, a certain amount of activated Ni-CNT is added to the copper source solution, after immersion for a certain time, filtration, washing and drying, the catalyst for catalyzing the reverse water gas shift of carbon dioxide is obtained.

[0041] The preparation method of the catalyst of the present application can prepare the above-mentioned catalyst, without using noble metal, simple process, low cost, and good industrial application prospect.

[0042] In the second aspect, the present application provides a preparation method of the catalyst for catalyzing the reverse water gas shift of carbon dioxide, comprising the following steps:

[0043] 1) heat treatment of the raw material system comprising a nickel source and a carbon source under a reducing atmosphere to obtain carbon nanotubes containing nickel elements;

[0044] 2) activation treatment of the carbon nanotubes containing nickel elements to obtain an activated intermediate;

[0045] 3) immersion treatment of the activated intermediate with a solution comprising a copper source to obtain the catalyst for catalyzing the reverse water gas shift of carbon dioxide.

[0046] In step 1) of the present application, the reducing atmosphere can be hydrogen, the nickel source can be nickel salt, for example, nickel oxide, and the carbon source can be ethane. The nickel source can be placed in a tube furnace, after the nitrogen gas is introduced to replace the air sufficiently, the reducing gas is introduced, heated to a certain temperature, then the carbon source is introduced, after a certain time of reaction, nitrogen gas is introduced again, and the temperature is lowered to room temperature under the nitrogen atmosphere, to obtain carbon nanotubes containing nickel elements (Ni-CNT). The reducing atmosphere can promote the reduction of nickel and the formation of carbon nanotubes, so that the nickel elements grow uniformly on the carbon nanotubes.

[0047] In step 2), the activation treatment can use carbon dioxide. Specifically, the carbon nanotubes containing nickel elements can be placed in a tube furnace, after the nitrogen gas is introduced to replace the air sufficiently, heated to a certain temperature, then the carbon dioxide is introduced for activation treatment, after a certain time of reaction, nitrogen gas is introduced again, and the temperature is lowered to room temperature under the nitrogen atmosphere, to obtain activated Ni-CNT. The activation treatment can increase the specific surface area and surface activity of the material, and provide more binding sites for the subsequent loading of copper.

[0048] In step 3), the copper source can be a copper salt, such as copper nitrate trihydrate and / or copper acetate. The copper source can be dissolved in deionized water to form a copper salt solution, and a certain amount of activated Ni-CNTs can be added to the copper salt solution. After immersion for a certain time, a catalyst for catalyzing the reverse water gas shift reaction of carbon dioxide is obtained. The immersion treatment can be an equal-volume immersion treatment. After the immersion treatment, the immersion product can be subjected to filtration, washing, and drying treatment to remove impurities and moisture from the catalyst. The immersion treatment can uniformly deposit copper ions on the surface of the carbon nanotubes, optimize the synergistic effect between copper and nickel elements, and improve the overall activity and selectivity of the catalyst.

[0049] The catalyst synthesis method of the present application is simple, the process conditions are easy to control, and the catalyst production cost is low. The catalyst does not use noble metals, has high carbon dioxide conversion rate and good carbon monoxide selectivity when catalyzing the reverse water gas reaction of carbon dioxide to generate carbon monoxide, and has good application prospects.

[0050] In some embodiments of the present application, the temperature of the heat treatment is 700-800℃, for example, it can be 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, or a range consisting of any two of them; the time is 2-12h, for example, it can be 2h, 4h, 5h, 7h, 10h, 12h, or a range consisting of any two of them.

[0051] In the present application, the temperature of the heat treatment is in the above range, which can effectively reduce the nickel ions in the nickel source to form metal nickel particles, which is conducive to promoting the uniform growth of carbon nanotubes on the nickel particles. It can also effectively pyrolyze the carbon source to form carbon nanotubes, enhance their electrical conductivity and thermal stability, and optimize the surface activity and pore structure of the carbon nanotubes, providing a basis for subsequent activation and copper loading.

[0052] The time of the heat treatment is in the above range, which provides sufficient time to ensure complete reduction of nickel and proper particle growth, avoiding excessive particle aggregation or sintering caused by too long time. It is also conducive to the full formation of carbon nanotubes.

[0053] In some embodiments of the present application, the carbon nanotubes containing nickel elements are activated by carbon dioxide. The temperature of the activation treatment is 600-700℃, for example, it can be 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, 660℃, 670℃, 680℃, 690℃, 700℃, or a range consisting of any two of them; the time is 1-2h, for example, it can be 1h, 1.2h, 1.5h, 1.7h, 2h, or a range consisting of any two of them.

[0054] Carbon dioxide can react with carbon source at high temperature to remove impurities and weakly bound carbon atoms on the surface, generating more active sites, which is conducive to improving the surface activity of the catalyst. And carbon dioxide can introduce microporous and mesoporous structures on the surface of carbon nanotubes, increasing the specific surface area and porosity, providing more binding sites for subsequent metal loading. The temperature of the activation treatment can promote the activation reaction, and will not cause damage to the structure of the carbon nanotubes. The activation time ensures the effectiveness of the activation process, while avoiding over-treatment.

[0055] In some embodiments, the impregnation treatment time is 12h-24h, for example, it can be 12h, 12h, 15h, 17h, 20h, 22h, 24h or a range consisting of any two of them.

[0056] The impregnation treatment time allows the copper source to fully penetrate into the pores of the carbon nanotubes, ensuring uniform distribution of copper ions on the surface of the carbon nanotubes. It also helps to form a stronger interaction between copper ions and the surface of carbon nanotubes, reducing the aggregation of metal particles during subsequent heat treatment. It can also improve the loading and dispersion of copper elements, thereby improving the overall activity and stability of the catalyst.

[0057] In a third aspect, the present application provides a method for preparing carbon monoxide, comprising the following steps: using the catalyst for catalyzing carbon dioxide reverse water gas shift reaction or the catalyst prepared by the method for preparing catalyst for catalyzing carbon dioxide reverse water gas shift reaction as described above to catalyze carbon dioxide to carry out reverse water gas reaction to obtain carbon monoxide.

[0058] The present application uses the catalyst provided in the first aspect or the catalyst prepared by the method provided in the second aspect to catalyze carbon dioxide to carry out reverse water gas reaction to obtain carbon monoxide, which can improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0059] In some embodiments, the temperature of the reverse water gas reaction can be 300℃-500℃, and the pressure of the reverse water gas reaction can be 0.15MPa-0.2MPa. Illustratively, the temperature of the reverse water gas reaction can be 300℃, 320℃, 350℃, 370℃, 400℃, 420℃, 450℃, 470℃, 500℃ or a range consisting of any two of them. The pressure of the reverse water gas reaction can be 0.15MPa, 0.16MPa, 0.17MPa, 0.18MPa, 0.19MPa, 0.2MPa or a range consisting of any two of them. The reaction temperature and time can improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide when the catalyst catalyzes carbon dioxide to carry out reverse water gas reaction to obtain carbon monoxide.

[0060] In some embodiments of the present application, the method for preparing carbon monoxide comprises the following steps:

[0061] 1) activating the catalyst for reverse water gas shift of carbon dioxide with hydrogen to obtain an activated catalyst;

[0062] 2) passing hydrogen and carbon dioxide into a fixed bed containing the activated catalyst for gas-solid contact at a temperature of 300-500 DEG C and a pressure of 0.15-0.2 MPa to perform reverse water gas shift to obtain carbon monoxide.

[0063] In the present application, the catalyst is first activated with hydrogen to obtain an activated catalyst, and then the activated catalyst is used to perform reverse water gas shift of carbon dioxide to obtain carbon monoxide.

[0064] In some embodiments, the temperature for the activation treatment can be 300-400 DEG C, and the time for the activation treatment can be 1.5-2.5 h. Illustratively, the temperature for the activation treatment can be 300 DEG C, 320 DEG C, 350 DEG C, 370 DEG C, 400 DEG C, or a range defined by any two of them. The time for the activation treatment can be 1.5 h, 1.8 h, 2 h, 2.2 h, 2.5 h, or a range defined by any two of them.

[0065] Specifically, in step 1), the catalyst is activated in a hydrogen atmosphere at 300-400 DEG C for 1.5-2.5 h to obtain an activated catalyst. It can be understood that after being prepared, the catalyst often needs to be activated to convert the inactive catalyst into an activated catalyst. The purpose of activation is to remove the oxidation layer or other impurities on the surface of the catalyst to expose more active sites.

[0066] In step 2), a certain amount of activated catalyst, for example, 0.5 g, is loaded into the reaction tube of a fixed bed reaction device, wherein the inner diameter of the reaction tube of the fixed bed reaction device is 10 mm and the length is 40 cm, and then the temperature of the fixed bed is adjusted to 300-500 DEG C, and the reaction raw materials hydrogen and carbon dioxide are started to be passed for gas-solid contact to perform reverse water gas shift, and the pressure is controlled in the range of 0.15-0.2 MPa. Under the action of the catalyst, carbon dioxide reacts with hydrogen to generate carbon monoxide and water.

[0067] The above catalyst is used in the present application to catalyze reverse water gas shift of carbon dioxide under mild conditions to obtain carbon monoxide. The catalyst has high activity, and thus can improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0068] In some embodiments of the present application, the volume ratio of hydrogen to carbon dioxide is (3-3.5):1.

[0069] The volume ratio of hydrogen and carbon dioxide in the present application is in the above range, which can make carbon dioxide and hydrogen fully react, finally generate carbon monoxide, and further improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide.

[0070] The technical solutions of the present application are further illustrated below in combination with specific examples.

[0071] Example 1

[0072] The preparation method of carbon monoxide in the present example comprises the following steps:

[0073] 1) Put 0.1 g of nickel oxide into a tube furnace, replace air with nitrogen, then pass in hydrogen, start heating, heat to 750℃, then pass in ethane, control the flow rate of ethane at 50 ml / min, react for 5 h, then pass in nitrogen again, cool to room temperature under nitrogen atmosphere, and obtain 2.8 g of carbon nanotubes containing nickel elements (Ni-CNT).

[0074] 2) Put the above-synthesized carbon nanotubes containing nickel elements (Ni-CNT) into a tube furnace, replace air with nitrogen, heat to 650℃, then pass in carbon dioxide, activate for 2 h, then pass in nitrogen again, cool to room temperature under nitrogen atmosphere, and obtain 2.61 g of activated Ni-CNT (nickel content 3%).

[0075] 3) Take 0.5 g of the activated Ni-CNT, take 0.1 g of Cu(NO3)2·3H2O, dissolve in deionized water with the same volume as the Ni-CNT to form a copper salt solution, add the activated Ni-CNT into the copper salt solution, immerse for 24 h, then filter, wash, and dry to obtain a Cu / Ni-CNT catalyst, marked as 5%Cu / 3%Ni-CNT.

[0076] 4) Activate the above catalyst in H2 atmosphere at 300℃ for 2 h to obtain an activated catalyst. The inner diameter of the reaction tube of the fixed bed reaction device is 10 mm, and the length is 40 cm. Put 0.5 g of the above activated catalyst into the reaction tube, adjust the temperature to 400℃, start passing in carbon dioxide and hydrogen as the reaction raw materials to perform gas-solid contact for reverse water gas shift reaction, wherein the volume ratio of hydrogen and carbon dioxide is 3:1, the reaction pressure is controlled at 0.2 MPa, the reaction product is connected to an online gas chromatograph for analysis, and the results are shown in Table 1.

[0077] Example 2

[0078] The preparation method of carbon monoxide in Example 2 is basically the same as that in Example 1, except that in step 1), the temperature of heat treatment is 720℃, and the time is 8h; after activation, 3.93g of 2%Ni-CNT is obtained; in step 3), 0.74g of Cu(CH3COO)2·H2O is weighed and dissolved in the same volume of deionized water as the Ni-CNT to form a copper salt solution, and the impregnation treatment time is 12h; in step 4), the temperature of reverse water gas shift reaction is 350℃, and the pressure is 0.15MPa.

[0079] Example 3

[0080] The preparation method of carbon monoxide in Example 3 is basically the same as that in Example 1, except that in step 1), the temperature of heat treatment is 780℃, and the time is 4h; in step 2), the temperature of activation treatment is 700℃, and the time is 1h; after activation, 3.14g of 2.5%Ni-CNT is obtained; in step 3), 0.60g of Cu(NO3)2·3H2O is weighed and dissolved in the same volume of deionized water as the Ni-CNT to form a copper salt solution, and the impregnation treatment time is 12h; in step 4), the temperature of reverse water gas shift reaction is 500℃, and the pressure is 0.15MPa.

[0081] Example 4

[0082] The preparation method of carbon monoxide in Example 4 is basically the same as that in Example 1, except that in step 1), the temperature of heat treatment is 700℃, and the time is 12h; in step 2), the temperature of activation treatment is 600℃, and the time is 1h; after activation, 3.7g of 2%Ni-CNT is obtained; in step 3), 0.35g of Cu(CH3COO)2·H2O is weighed and dissolved in the same volume of deionized water as the Ni-CNT to form a copper salt solution; in step 4), the temperature of reverse water gas shift reaction is 450℃, and the pressure is 0.15MPa.

[0083] Example 5

[0084] The preparation method of carbon monoxide in Example 5 is basically the same as that in Example 1, except that in step 1), the temperature of heat treatment is 800℃, and the time is 4h; in step 2), the temperature of activation treatment is 630℃, and after activation, 4.21g of 2%Ni-CNT is obtained; in step 3), 0.4g of Cu(CH3COO)2·H2O is weighed and dissolved in the same volume of deionized water as the Ni-CNT to form a copper salt solution, and the impregnation treatment time is 12h; in step 4), the temperature of reverse water gas shift reaction is 420℃.

[0085] Comparative Example 1

[0086] The preparation method of carbon monoxide in Comparative Example 1 is basically the same as that in Example 1, except that steps 2) and 3) are omitted, that is, using carbon nanotubes containing nickel element (Ni-CNT) as catalyst to catalyze the reverse water gas shift reaction.

[0087] Comparative Example 2

[0088] The preparation method of carbon monoxide in Comparative Example 2 is basically the same as that in Example 1, except that step 3) is omitted, that is, using activated carbon nanotubes containing nickel element (Ni-CNT) as catalyst to catalyze the reverse water gas shift reaction.

[0089] Comparative Example 3

[0090] The preparation method of carbon monoxide in the present comparative example comprises the following steps:

[0091] 1) Using commercially available CNT as a carrier, 0.1 g of Cu(NO3)2·3H2O was weighed and dissolved in the same volume of deionized water as the CNT to form a copper salt solution, and 0.5 g of commercially available CNT was added to the copper salt solution. After 24 hours of immersion, filtration, washing and drying, a Cu / CNT catalyst was obtained, marked as 5% Cu / CNT.

[0092] 2) The above catalyst was activated at 300°C for 2 hours in a H2 atmosphere to obtain an activated catalyst. The inner diameter of the reaction tube of the fixed bed reaction device was 10 mm and the length was 40 cm. 0.5 g of the above activated catalyst was loaded into the reaction tube, the temperature was adjusted to 400°C, and the reaction raw materials carbon dioxide and hydrogen were started to be introduced for gas-solid contact to perform the reverse water gas shift reaction. The volume ratio of hydrogen to carbon dioxide was 3:1, and the reaction pressure was controlled at 0.2 MPa.

[0093] Table 1 Catalyst composition, carbon monoxide selectivity and carbon dioxide conversion rate of Examples 1-5 and Comparative Examples 1-3

[0094]

[0095] As can be seen from Table 1, compared with the comparative examples, the catalyst for catalyzing the reverse water gas shift of carbon dioxide provided by the present application uses carbon nanotubes containing nickel element as carrier, and copper and nickel as active metals, and the synergistic effect can improve the catalytic activity of the catalyst, so that the catalyst can improve the conversion rate of carbon dioxide and the selectivity of carbon monoxide when catalyzing the reverse water gas reaction of carbon dioxide to generate carbon monoxide.

[0096] After 100 hours of reverse water gas reaction, the selectivity of carbon monoxide of the catalyst in Example 1 was 96.7%, and the conversion rate of carbon dioxide was 43.0%, indicating that the catalyst had good service life.

[0097] Compared with Examples 4-5, in the catalysts of Examples 1-3, the mass percentage of copper element is between 4%-6%, which can further improve the selectivity of carbon monoxide.

[0098] It should be understood, however, that the scope of the application is not limited to the specific embodiments illustrated herein, but includes any and all embodiments which come within the scope of the following claims and their equivalents. It is therefore desired that the present application be interpreted as broadly as possible in order to provide a complete disclosure of the general inventive features and so as to encompass all such changes and modifications.

Claims

1. A catalyst for catalyzing the reverse water-gas shift of carbon dioxide, characterized in that, It includes carbon nanotubes containing nickel and copper elements loaded on the carbon nanotubes; wherein the carbon nanotubes containing nickel are obtained by heat treatment of a raw material system including a nickel source and a carbon source under a reducing atmosphere.

2. The catalyst for catalytic carbon dioxide reverse water gas shift according to claim 1, characterized in that, The catalyst for catalytic carbon dioxide reverse water gas conversion comprises, by mass percentage: 2%-6% copper, 2%-4% nickel, and the balance being carbon nanotubes.

3. The catalyst for catalytic carbon dioxide reverse water gas shift according to claim 2, characterized in that, The catalyst for catalytic carbon dioxide reverse water gas conversion comprises, by mass percentage: 4%-6% copper, 2%-3% nickel, and the balance being carbon nanotubes.

4. The catalyst for catalytic carbon dioxide reverse water gas shift according to any one of claims 1-3, characterized in that, The catalyst for catalyzing the reverse water-gas shift of carbon dioxide is prepared by a method comprising the following steps: The raw material system, including a nickel source and a carbon source, is subjected to heat treatment. The resulting nickel-containing carbon nanotubes are then activated. The activated intermediate obtained from the activation treatment is impregnated with a solution including a copper source to obtain the catalyst for catalytic carbon dioxide reverse water gas conversion.

5. A method for preparing a catalyst for catalytic carbon dioxide reverse water-gas shift as described in any one of claims 1-4, characterized in that, Includes the following steps: 1) Under a reducing atmosphere, a raw material system including a nickel source and a carbon source is heat-treated to obtain carbon nanotubes containing nickel. 2) The nickel-containing carbon nanotubes are activated to obtain an activated intermediate; 3) The activated intermediate is impregnated with a solution containing a copper source to obtain the catalyst for catalytic carbon dioxide reverse water gas conversion.

6. The method for preparing the catalyst for catalytic carbon dioxide reverse water-gas shift according to claim 5, characterized in that, The heat treatment temperature is 700℃-800℃, and the time is 2h-12h.

7. The method for preparing the catalyst for catalytic carbon dioxide reverse water-gas shift according to claim 5, characterized in that, The nickel-containing carbon nanotubes were activated using carbon dioxide. The activation treatment is performed at a temperature of 600℃-700℃ for 1-2 hours. And / or, the impregnation treatment time is 12h-24h.

8. A method for preparing carbon monoxide, characterized in that, The process includes the following steps: using the catalyst for catalytic carbon dioxide reverse water gas conversion according to any one of claims 1-4 or the catalyst for catalytic carbon dioxide reverse water gas conversion prepared by the method of preparing the catalyst for catalytic carbon dioxide reverse water gas conversion according to any one of claims 5-7 to catalyze carbon dioxide to undergo a reverse water gas reaction to obtain carbon monoxide.

9. The method for preparing carbon monoxide according to claim 8, characterized in that, The method for preparing carbon monoxide includes the following steps: 1) The catalyst for catalytic carbon dioxide reverse water-gas conversion is activated using hydrogen to obtain an activated catalyst; 2) At a temperature of 300℃-500℃ and a pressure of 0.15MPa-0.2MPa, hydrogen and carbon dioxide are introduced into a fixed bed containing the activated catalyst to carry out the reverse water gas reaction and obtain carbon monoxide.

10. The method for preparing carbon monoxide according to claim 9, characterized in that, The volume ratio of hydrogen to carbon dioxide is (3-3.5):1.

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