A catalyst, its preparation method and application

Abstract

This application provides a catalyst comprising a support and an active component loaded on the support; the support is CeO2; the active component is Ir clusters and Cu atoms. This application also provides a method for reverse water-gas shift reaction, comprising the following steps: after reduction using the catalyst described in any of the above technical solutions, a catalytic feed gas is subjected to a reverse water-gas shift reaction; the feed gas is CO2 and H2. The catalyst provided in this application exhibits high catalytic activity in the reverse water-gas shift reaction, possessing both high carbon dioxide conversion rate and high carbon monoxide selectivity. Experimental results show that the catalyst provided in this application achieves a CO2 conversion rate of 46.1% and a selectivity greater than 99.5% under conditions of 600℃ and 500 L / g / h.

Description

Technical Field

[0001] This application relates to the field of catalyst technology, and in particular to a catalyst, its preparation method and application. Background Technology

[0002] For a long time, human activities have heavily relied on fossil fuels. However, the excessive development and use of fossil fuels has led to carbon dioxide emissions and caused serious environmental and energy problems, including but not limited to the greenhouse effect and sea-level rise, which greatly hinder the achievement of carbon neutrality goals. Directly converting carbon dioxide, a greenhouse gas generated by human activities, into high-value-added chemicals via catalytic hydrogenation is a favorable strategy to alleviate the current environmental and energy crisis and contribute to achieving this goal. Among various carbon dioxide hydrogenation reactions, compared to hydrogenation to long-chain olefins such as gasoline and diesel, the reverse water-gas reaction (CO2 + H2 = CO + H2O) is a powerful and effective way to eliminate the greenhouse gas carbon dioxide due to its low operating pressure and high equilibrium conversion rate. Furthermore, the reverse water-gas reaction can produce syngas with adjustable proportions, which can be coupled with downstream Fischer-Tropsch synthesis reactions to prepare a series of high-value-added chemicals, attracting widespread attention.

[0003] Under normal pressure, the reverse water-gas reaction is often affected by its side reaction, methanation (CO2 + 4H2 = CH4 + 2H2O), which reduces the product selectivity. This not only reduces the production efficiency of the product but also increases the cost of subsequent gas separation, further diminishing the industrial application value of the reaction. Therefore, developing a reverse water-gas change catalyst with high conversion and high selectivity is particularly important. Summary of the Invention

[0004] In view of this, the technical problem solved by this application is to provide a catalyst, its preparation method and application. The catalyst provided by this application has both high carbon dioxide conversion rate and carbon monoxide selectivity in the reverse water-gas shift reaction.

[0005] This application provides a catalyst, comprising a support and an active component supported on the support; The carrier is CeO2; The active components are Ir clusters and Cu atoms.

[0006] In some specific implementations, the carrier is CeO2.

[0007] In some specific implementations, the mass fraction of the Ir cluster is 0.2% to 1.5%, and the mass fraction of the Cu atoms is 0.2% to 5%.

[0008] This application also provides a method for preparing a catalyst, comprising the following steps: The support was mixed with an Ir source and a Cu source, and the reaction yielded a Cu-Ir / supported catalyst. The carrier is CeO2.

[0009] Some specific implementation methods include: The support was mixed with the Ir source, and the reaction yielded an Ir / supported catalyst. The Ir / supported catalyst was mixed with a Cu source, and the reaction yielded a Cu-Ir / supported catalyst.

[0010] In some specific implementations, the Ir source is chloroiridium acid.

[0011] In some specific implementations, the Cu source is copper nitrate trihydrate.

[0012] This application also provides a method for reverse water-gas shift, comprising the following steps: After reducing the catalyst described in any of the above technical solutions or the catalyst prepared by the preparation method described in any of the above technical solutions, the catalytic feed gas undergoes a reverse water-gas shift reaction. The raw materials are CO2 and H2.

[0013] In some specific implementations, the reducing gas is H2; the gas space velocity of the reducing gas is 100 L / g / h to 500 L / g / h. The reduction temperature is 400℃~800℃, the heating rate is 5℃ / min~20℃ / min, and the reduction time is 0.5h~4h.

[0014] In some specific implementations, the volume ratio of CO2:H2 in the raw gas is 1 to 8:1.

[0015] In some specific implementations, the reaction temperature is 500℃~700℃; The space velocity of the reaction is 30 L / g / h to 600 L / g / h.

[0016] This application provides a catalyst comprising a support and an active component loaded on the support; the support is CeO2; the active component is Ir clusters and Cu atoms. The catalyst provided by this application exhibits good dispersibility, with Ir clusters and Cu atoms uniformly distributed on the CeO2 support. Simultaneously, the highly dispersed Cu atoms effectively prevent the aggregation of Ir clusters, maintaining their small size distribution. When used in a reverse water-gas shift reaction, the catalyst provided by this application demonstrates high catalytic activity, exhibiting both high CO2 conversion and high carbon monoxide selectivity. Experimental results show that the catalyst provided by this application achieves a CO2 conversion of 46.1% and a selectivity greater than 99.5% at 600℃ and 500 L / g / h. Attached Figure Description

[0017] Figure 1 These are high-angle annular dark-field images-scanning transmission electron microscopy images and X-ray energy dispersive spectroscopy elemental analyses of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application. Figure 1 a is a high-angle annular dark-field image-scanning transmission electron microscope image of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application. Figure 1 b is the X-ray energy dispersive spectroscopy elemental analysis diagram of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application; Figure 2 The high-angle annular dark-field image-scanning transmission electron microscope image and X-ray energy dispersive spectroscopy elemental analysis diagram of the Ir / CeO2-1 catalyst provided in Comparative Example 1 of this application are shown below. Figure 2 a is a high-angle annular dark-field image-scanning transmission electron microscope image of the Ir / CeO2-1 catalyst provided in Comparative Example 1 of this application. Figure 2 b is the X-ray energy dispersive spectroscopy elemental analysis diagram of the Ir / CeO2-1 catalyst provided in Comparative Example 1 of this application; Figure 3 Fourier transform infrared spectra of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application and the Ir / CeO2-1 catalyst provided in Comparative Example 1 under a carbon monoxide atmosphere; Figure 4 The carbon dioxide temperature-programmed desorption results are shown for the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application and the Ir / CeO2-1 catalyst provided in Comparative Example 1. Figure 5 The CO2 conversion rate test results of the reverse water-gas shift reaction catalytic reaction of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application, the Ir / CeO2-1 catalyst provided in Comparative Example 1, and the Cu / CeO2-1 catalyst provided in Comparative Example 2; Figure 6 The CO selectivity test results of the reverse water-gas shift reaction catalytic reaction of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application, the Ir / CeO2-1 catalyst provided in Comparative Example 1, and the Cu / CeO2-1 catalyst provided in Comparative Example 2; Figure 7 The CO2 conversion rate test results of the reverse water-gas shift reaction catalytic reaction of the Cu-Ir / CeO2-1 catalyst provided in Example 1, the Cu-Ir / CeO2-2 catalyst provided in Example 2, and the Cu-Ir / CeO2-3 catalyst provided in Example 3 of this application; Figure 8The CO selectivity test results of the reverse water-gas shift reaction catalytic reaction of the Cu-Ir / CeO2-1 catalyst provided in Example 1, the Cu-Ir / CeO2-2 catalyst provided in Example 2, and the Cu-Ir / CeO2-3 catalyst provided in Example 3 of this application; Figure 9 In-situ transient gas-cutting surface reaction experiments were conducted on the Cu-Ir / CeO2-1 catalyst provided in Example 1 and the Ir / CeO2-1 catalyst provided in Comparative Example 1 under carbon dioxide-hydrogen switching conditions. Figure 9 a represents the in-situ transient gas-cutting surface reaction experiment of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application under carbon dioxide-hydrogen switching. Figure 9 b is an in-situ transient gas-cutting surface reaction experiment of the Ir / CeO2-1 catalyst provided in Comparative Example 1 of this application under carbon dioxide-hydrogen switching. Detailed Implementation

[0018] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0019] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0020] It should be understood that the order of steps or the sequence of actions is not important as long as this application remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0021] The use of any and all instances or exemplary language such as “e.g.” or “including” herein is merely intended to better illustrate the application and does not constitute a limitation on the scope of the application unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of this application.

[0022] Furthermore, the numerical ranges and parameters used to define this application are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any numerical value inevitably contains standard deviations due to individual test methods. Therefore, unless otherwise explicitly stated, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0023] This application provides a catalyst, comprising a support and an active component supported on the support; The carrier is CeO2; The active components are Ir clusters and Cu atoms.

[0024] The catalyst provided in this application includes a support, wherein the support is CeO2, and this application does not impose any special restrictions on the source of the support.

[0025] The CeO2 support described in this application can be prepared according to the following method: The Ce source was dissolved and co-precipitated, and then calcined to obtain the CeO2 support.

[0026] Specifically, after dissolving the Ce source in water, a precipitant is added for co-precipitation. The resulting precipitate is then filtered, dried, and calcined to obtain the CeO2 support.

[0027] In some specific implementations, the Ce source can be a soluble salt such as nitrate or chloride, preferably nitrate. In some specific implementations, the dissolution is preferably carried out under stirring conditions. In some specific implementations, the precipitant is preferably concentrated ammonia solution with a concentration of 25% to 28%. In some specific implementations, the ratio of Ce source, water, and precipitant is 1g to 5g: 25mL to 200mL: 0.3mL to 2mL, preferably 1g to 3g: 50mL to 150mL: 0.5mL to 1.5mL. To achieve more concentrated nucleation and more uniform particle size, and to ensure a more complete reaction and more stable particle structure, in some specific implementations, the precipitant is preferably added rapidly to the Ce source aqueous solution and aging is carried out with vigorous stirring for 24h to 36h, preferably 24h. In some specific implementations, the filtration is preferably vacuum filtration. In some specific implementations, the drying temperature is 40℃~80℃, preferably 50℃~70℃, and the time is 8h~17h, preferably 10h~15h. In some specific implementations, the calcination temperature is 300℃~700℃, preferably 400℃~600℃, the heating rate is 1℃ / min~10℃ / min, preferably 4℃ / min~6℃ / min, and the time is 2h~8h, preferably 3h~7h.

[0028] The catalyst provided in this application comprises an active component supported on the support, wherein the active component is Ir clusters and Cu atoms. In some specific implementations, the mass fraction of the Ir clusters is 0.2% to 1.5%, preferably 0.2% to 1%, more preferably 0.5%; and the mass fraction of the Cu atoms is 0.2% to 5%, preferably 0.5% to 3%, more preferably 2%.

[0029] The Cu-Ir / supported catalyst provided in this application, wherein Ir is uniformly distributed on the support surface in the form of clusters and Cu in the form of highly dispersed atoms, exhibits both high carbon dioxide conversion and carbon monoxide selectivity in the reverse water-gas shift reaction. Experimental results show that the catalyst provided in this application achieves a CO2 conversion of 46.1% and a selectivity greater than 99.5% at 600℃ and 500 L / g / h.

[0030] This application also provides a method for preparing a catalyst, comprising the following steps: The support was mixed with an Ir source and a Cu source, and the reaction yielded a Cu-Ir / supported catalyst. The carrier is CeO2.

[0031] Specifically, the support is dissolved in deionized water and then mixed with an Ir source and a Cu source to obtain a Cu-Ir / support catalyst after the reaction.

[0032] The specific types and preparation methods of the carriers are as described above, and will not be repeated here. In some specific implementations, the dissolution is preferably carried out under stirring conditions, and the stirring time is 10 min to 50 min, preferably 20 min to 40 min. In some specific implementations, the Ir source is chloroiridium acid. In some specific implementations, the Cu source is copper nitrate trihydrate. This application does not impose any special restrictions on the ratio of the carrier, Ir source, and Cu source, as long as the loading range of the active components (Ir clusters and Cu atoms) on the carrier is met. The specific loading amounts are as described above, and this application does not impose any special restrictions. In some specific implementations, the solution concentration of the Ir source is 10 mg Ir / mL, and the ratio of the solution volume of the Ir source to the mass of the carrier is 100 μL to 400 μL: 500 mg, preferably 200 μL to 300 μL: 500 mg, more preferably 250 μL: 500 mg. In some specific implementations, the concentration of the Cu source solution is 10 mg Cu / mL, and the ratio of the Cu source solution volume to the carrier mass is 200 μL~2000 μL:500 mg, preferably 250 μL~1500 μL:500 mg, and more preferably 1000 μL:500 mg. In some specific implementations, it is preferable to slowly add the Ir source and Cu source to the carrier dispersion. In some specific implementations, it is preferable to carry out the reaction under stirring conditions, and the reaction time is 0.5 h~3 h, preferably 0.1 h~1.5 h.

[0033] In some specific implementations, it is preferable to mix the support with the Ir source to obtain an Ir / support catalyst after the reaction; then, the Ir / support catalyst is mixed with a Cu source to obtain a Cu-Ir / support catalyst after the reaction. This process allows the Cu precursor salt to be more uniformly dispersed on the support, avoiding alloying.

[0034] Specifically, the support is first dissolved in deionized water, then mixed with an Ir source, and the reaction yields an Ir / supported catalyst. The preparation process and conditions of the Ir / supported catalyst in this application are the same as those of the Cu-Ir / supported catalyst described above, except that a Cu source is not added, which will not be repeated here.

[0035] After obtaining the Ir / supported catalyst, the Ir / support is dissolved in deionized water and then mixed with a Cu source. The reaction yields a Cu-Ir / supported catalyst. In some specific implementations, the dissolution is preferably carried out under stirring conditions for 10-50 minutes, preferably 20-40 minutes. In some specific implementations, the Cu source is copper nitrate trihydrate. In some specific implementations, the concentration of the Cu source solution is 10 mg Cu / mL, and the ratio of the Cu source solution volume to the mass of the Ir / supported catalyst is 200-2000 μL:500 mg, preferably 250-1500 μL:500 mg, more preferably 1000 μL:500 mg. In some specific implementations, the Cu source is preferably slowly added to the Ir / support dispersion. In some specific implementations, the reaction is preferably carried out under stirring conditions for 0.5-3 hours, preferably 0.1-1.5 hours.

[0036] After the reaction is complete, the Cu-Ir / support reaction solution is preferably subjected to vacuum rotary evaporation until it is completely evaporated, and then calcined to obtain the catalyst. In some specific implementations, during the vacuum rotary evaporation process, the temperature is 40℃~80℃, preferably 50℃~70℃; the rotation speed is 80rpm~220rpm, preferably 100rpm~200rpm; and the vacuum degree is 5hPa~50hPa, preferably 10hPa~30hPa. In some specific implementations, the calcination temperature is 400℃~800℃, preferably 500℃~700℃, the heating rate is 5℃ / min~15℃ / min, preferably 8℃ / min~12℃ / min, and the time is 1h~5h, preferably 1h~3h.

[0037] This application also provides a method for reverse water-gas shift, comprising the following steps: After reducing the catalyst described in any of the above technical solutions or the catalyst prepared by the preparation method described in any of the above technical solutions, the catalytic feed gas undergoes a reverse water-gas shift reaction. The raw materials are CO2 and H2.

[0038] This application preferably uses a fixed-bed reactor to carry out the above-mentioned reaction, wherein the catalyst described in any of the above technical solutions is loaded onto the fixed-bed reactor along with quartz sand for reaction. When the catalyst described in the above-mentioned technical solutions of this application is applied to the reverse water-gas shift reaction, the catalyst needs to be pre-reduced.

[0039] In some specific implementations, the mass ratio of the catalyst to the quartz sand is 0.01~0.05:1, preferably 0.01~0.03:1. In some specific implementations, the mesh size of the quartz sand is 30 mesh~70 mesh, preferably 40 mesh~60 mesh. In some specific implementations, the reducing gas is H2. In some specific implementations, the gas space velocity of the reducing gas is 100 L / g / h~500 L / g / h, preferably 200 L / g / h~500 L / g / h. In some specific implementations, the reduction temperature is 400℃~800℃, preferably 500℃~700℃, the heating rate is 5℃ / min~20℃ / min, preferably 5℃ / min~15℃ / min, and the reduction time is 0.5h~4h, preferably 1h~3h.

[0040] After reduction, the reduced catalyst is used to catalyze the feed gas containing CO2 and H2 through a reverse water-gas shift reaction to obtain carbon monoxide product.

[0041] In some specific implementations, the volume ratio of CO2:H2 in the feed gas is 1~8:1, preferably 2~5:1, and more preferably 2~4:1. In some specific implementations, the reverse water-gas shift reaction further includes N2 as an internal standard gas, and the volume ratio of CO2:H2:N2 is 1~5:1:0.1~0.5, preferably 2~4:1:0.1~0.3. In some specific implementations, the flow rate of the feed gas is 10mL / min~200mL / min, corresponding to a space velocity of 30L / g / h~600L / g / h, preferably 50mL / min~200mL / min, corresponding to a space velocity of 150L / g / h~600L / g / h, and more preferably 100mL / min~200mL / min, corresponding to a space velocity of 300L / g / h~600L / g / h. In some specific implementations, the reaction temperature is 400℃~800℃, preferably 500℃~700℃.

[0042] In some specific implementations, more preferably, the temperature for the reverse water-gas reaction catalytic test is 600°C and the space velocity is 500 L / g / h. At the current temperature, the equilibrium conversion rate of the reaction is 60.3%, while at a high space velocity of 500 L / g / h, the catalyst conversion rate can deviate from the equilibrium conversion rate, preventing the generated carbon monoxide from being hydrogenated to methane in one step.

[0043] This application provides a catalyst comprising a support and an active component loaded on the support; the support is CeO2; the active component is Ir clusters and Cu atoms. The catalyst provided by this application exhibits good dispersibility, with Ir clusters and Cu atoms uniformly distributed on the CeO2 support. Simultaneously, the highly dispersed Cu atoms effectively prevent the aggregation of Ir clusters, maintaining their small size distribution. When used in a reverse water-gas shift reaction, the catalyst provided by this application demonstrates high catalytic activity, exhibiting both high CO2 conversion and high carbon monoxide selectivity. Experimental results show that the catalyst provided by this application achieves a CO2 conversion of 46.1% and a selectivity greater than 99.5% at 600℃ and 500 L / g / h.

[0044] The present invention is further illustrated below with reference to the embodiments. The scope of protection of the present invention is not limited to the following embodiments.

[0045] Example 1

[0046] In this embodiment, the Cu-Ir / CeO2-1 catalyst was prepared using the following synthesis method: Step 1: Synthesis of cerium oxide support: Add 2g of cerium nitrate hexahydrate crystals to 100mL of deionized water and stir to dissolve. Quickly add 1mL of concentrated ammonia and stir vigorously for 24h. Then, filter under vacuum, dry at 60℃ for 12h, and calcine at 5℃ / min to 500℃ and maintain for 4h to obtain cerium oxide support.

[0047] Step 2: Ir loading: Disperse 500 mg of the cerium oxide support prepared in Step 1 into 50 mL of deionized water and stir for 30 min. Slowly add 250 μL of 10 mg Ir / mL solution (Ir source selected from chloroiridic acid) to the above cerium oxide suspension and stir for 1 h. Transfer to a 100 mL round-bottom flask, fix it on a rotary evaporator, set the water bath temperature to 60°C, the stirring speed to 150 rpm, the vacuum pressure to 20 hPa, and rotary evaporate for 30 min. Scrape the obtained solid with a spatula, and finally raise the temperature to 600°C at 10°C / min and hold for 2 h to obtain the Ir / CeO2-1 catalyst.

[0048] Step 3: Cu loading: Disperse 500 mg of the Ir / CeO2-1 catalyst prepared in Step 2 into 50 mL of deionized water and stir for 30 min. Slowly add 1000 μL of 10 mg Cu / mL solution (Cu source selected from copper nitrate trihydrate) to the above Ir-CeO2-1 suspension and stir for 1 h. Transfer to a 100 mL round-bottom flask, fix it on a rotary evaporator, set the water bath temperature to 60°C, the stirring speed to 150 rpm, the vacuum pressure to 20 hPa, and rotary evaporate for 30 min. Scrape the obtained solid with a spatula, and finally raise the temperature to 600°C at 10°C / min and hold for 2 h to obtain the Cu-Ir / CeO2-1 catalyst.

[0049] Example 2

[0050] In this embodiment, the Cu-Ir / CeO2-2 catalyst was prepared, and the synthesis method is as follows: Step 1: Same as Example 1.

[0051] Step 2: Same as Example 1.

[0052] Step 3: Cu loading: Disperse 500 mg of the Ir / CeO2-1 catalyst prepared in Step 2 into 50 mL of deionized water and stir for 30 min. Slowly add 250 μL of 10 mg Cu / mL solution (Cu source selected from copper nitrate trihydrate) to the above Ir-CeO2-1 suspension and stir for 1 h. Transfer to a 100 mL round-bottom flask, fix it on a rotary evaporator, set the water bath temperature to 60°C, the stirring speed to 150 rpm, the vacuum pressure to 20 hPa, and rotary evaporate for 30 min. Scrape the obtained solid with a spatula, and finally raise the temperature to 600°C at 10°C / min and hold for 2 h to obtain the Cu-Ir / CeO2-2 catalyst.

[0053] Example 3

[0054] In this embodiment, the Cu-Ir / CeO2-3 catalyst was prepared using the following synthesis method: Step 1: Same as Example 1.

[0055] Step 2: Same as Example 1.

[0056] Step 3: Cu loading: Disperse 500 mg of the Ir / CeO2-1 catalyst prepared in Step 2 into 50 mL of deionized water and stir for 30 min. Slowly add 1500 μL of 10 mg Cu / mL solution (Cu source selected from copper nitrate trihydrate) to the above Ir-CeO2-1 suspension and stir for 1 h. Transfer to a 100 mL round-bottom flask, fix it on a rotary evaporator, set the water bath temperature to 60°C, the stirring speed to 150 rpm, and the vacuum pressure to 20 hPa. Rotary evaporate for 30 min, scrape off the solid obtained with a spatula, and finally raise the temperature to 600°C at 10°C / min and hold for 2 h to obtain the Cu-Ir / CeO2-3 catalyst.

[0057] Comparative Example 1

[0058] The comparative example of preparing the Ir / CeO2-1 catalyst is as follows: Step 1: Same as Step 1 in Example 1, to obtain the cerium oxide support; Step 2: Loading Ir: Same as Step 2 in Example 1, to obtain the Ir / CeO2-1 catalyst.

[0059] Comparative Example 2

[0060] The comparative example prepared a Cu / CeO2-1 catalyst, and the synthesis method is as follows: Step 1: Same as Step 1 in Example 1, to obtain the cerium oxide support; Step 2: Cu loading: Disperse 500 mg of the cerium oxide support prepared in Step 1 into 50 mL of deionized water and stir for 30 min. Slowly add 1000 μL of 10 mg Cu / mL solution (Cu source selected from copper nitrate trihydrate) to the above cerium oxide suspension and stir for 1 h. Transfer to a 100 mL round-bottom flask, fix it on a rotary evaporator, set the water bath temperature to 60°C, the stirring speed to 150 rpm, the vacuum pressure to 20 hPa, and rotary evaporate for 30 min. Scrape the obtained solid with a spatula, and finally raise the temperature to 600°C at 10°C / min and hold for 2 h to obtain the Cu / CeO2-1 catalyst.

[0061] Experimental Example 1

[0062] High-angle annular dark-field scanning transmission electron microscopy (STEM) images and X-ray energy dispersive spectroscopy (EDS) elemental analyses were performed on the catalysts of Example 1 and Comparative Example 1. The results are shown in [reference needed]. Figure 1 and Figure 2 , Figure 1 These are high-angle annular dark-field images-scanning transmission electron microscope images and X-ray energy dispersive spectroscopy elemental analysis diagrams of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application. Figure 1 a is a high-angle annular dark-field image-scanning transmission electron microscope image of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application. Figure 1 b is the X-ray energy dispersive spectroscopy elemental analysis diagram of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application; Figure 2 The high-angle annular dark-field image-scanning transmission electron microscope image and X-ray energy dispersive spectroscopy elemental analysis diagram of the Ir / CeO2-1 catalyst provided in Comparative Example 1 of this application are shown below. Figure 2 a is a high-angle annular dark-field image-scanning transmission electron microscope image of the Ir / CeO2-1 catalyst provided in Comparative Example 1 of this application. Figure 2 b is the X-ray energy dispersive spectroscopy elemental analysis diagram of the Ir / CeO2-1 catalyst provided in Comparative Example 1 of this application. Figure 1 It can be seen that Ir mainly exists in cluster form, while Cu exists on the catalyst surface in the form of highly dispersed atoms. From... Figure 2 It can be seen that Ir mainly exists in the catalyst in the form of clusters.

[0063] Fourier transform infrared spectroscopy analysis was performed on the catalysts of Example 1 and Comparative Example 1 above. The results are shown in [reference needed]. Figure 3 , Figure 3The Fourier transform infrared spectra of the Cu-Ir / CeO2-1 catalyst provided in Example 1 and the Ir / CeO2-1 catalyst provided in Comparative Example 1 under a carbon monoxide atmosphere are shown. Figure 3 It can be seen that Cu-Ir / CeO2-1 mainly exhibits adsorption on Cu, while Ir / CeO2-1 mainly exhibits linear adsorption on Ir, which is consistent with the electron microscopy results.

[0064] The results of carbon dioxide temperature-programmed desorption of the catalysts of Example 1 and Comparative Example 1 are shown in the figure. Figure 4 , Figure 4 The results of carbon dioxide temperature-programmed desorption are shown for the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application and the Ir / CeO2-1 catalyst provided in Comparative Example 1. Figure 4 It can be seen that the Cu-Ir / CeO2-1 catalyst has a higher CO2 adsorption capacity than the Ir / CeO2-1 catalyst, which can effectively promote the activation of reaction molecules.

[0065] Experimental Example 2

[0066] The performance of the catalysts in the above embodiments and comparative examples was evaluated using the following test methods: The reverse water-gas shift reaction catalytic experiment was conducted in a fixed-bed reactor (Quzhou Wode Instrument Co., Ltd.) at 600°C. The pretreatment gas flow rate was 100 mL / min, H2; the feed gas flow rate was 167 mL / min, with a composition of 96 vol% CO2 / H2 (CO2:H2=3:1) and 4 vol% N2 (as internal standard). 20 mg of catalyst was mixed with 1 g of 40–60 mesh quartz sand and placed in a 9 mm inner diameter quartz tube, which was then inserted into the fixed-bed reactor. All products from the reactor were introduced into a gas chromatograph (Shimadzu GC2014) in gaseous state. H2, CO, CO2, and N2 were separated by a TDX carbon molecular sieve column and analyzed by a thermal conductivity detector (TCD); other products were passed through a PONA capillary column and analyzed by a flame ionization detector (FID). Only carbon monoxide and methane were detected in the products. At the start of the test, pretreatment gas was introduced first, and the temperature was increased to 600°C at a rate of 10°C / min. After maintaining the temperature for 2 hours, the pretreatment gas was stopped and the raw material gas was introduced.

[0067] See the catalyst performance evaluation results. Figures 5-8 , Figure 5 The CO2 conversion results of the reverse water-gas shift reaction catalyzed by the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application, the Ir / CeO2-1 catalyst provided in Comparative Example 1, and the Cu / CeO2-1 catalyst provided in Comparative Example 2 are shown. Figure 6The results show the CO selectivity of the reverse water-gas shift reaction catalyzed by the Cu-Ir / CeO2-1 catalyst provided in Example 1, the Ir / CeO2-1 catalyst provided in Comparative Example 1, and the Cu / CeO2-1 catalyst provided in Comparative Example 2. Figure 7 The CO2 conversion rate test results of the reverse water-gas shift reaction catalyzed by the Cu-Ir / CeO2-2 catalyst provided in Example 2 and the Cu-Ir / CeO2-3 catalyst provided in Example 3 of this application are shown. Figure 8 The CO selectivity test results of the reverse water-gas shift reaction catalyzed by the Cu-Ir / CeO2-2 catalyst provided in Example 2 and the Cu-Ir / CeO2-3 catalyst provided in Example 3 of this application.

[0068] Depend on Figures 5-8 It can be seen that, compared with Ir / CeO2-1 and Cu / CeO2-1 catalysts supported on a single active component, Cu-Ir / CeO2 catalyst exhibits high CO2 conversion and CO selectivity, indicating that the introduction of Cu can increase its conversion of reactant CO2 and selectivity of product CO.

[0069] Experimental Example 3

[0070] In-situ transient gas-cutting surface reaction experiments were conducted on the catalysts of Example 1 and Comparative Example 1. The results are shown in [reference needed]. Figure 9 , Figure 9 In-situ transient gas-cutting surface reaction experiments were conducted on the Cu-Ir / CeO2-1 catalyst provided in Example 1 and the Ir / CeO2-1 catalyst provided in Comparative Example 1 under carbon dioxide-hydrogen switching conditions. Figure 9 a represents the in-situ transient gas-cutting surface reaction experiment of the Cu-Ir / CeO2-1 catalyst provided in Example 1 of this application under carbon dioxide-hydrogen switching. Figure 9 b represents the in-situ transient gas-cutting surface reaction experiment of the Ir / CeO2-1 catalyst provided in Comparative Example 1 of this application under carbon dioxide-hydrogen switching. Figure 9 It can be seen that the Cu-Ir / CeO2-1 catalyst produces less CH4 than the Ir / CeO2-1 catalyst, which is consistent with the results of the fixed bed test, further demonstrating that the addition of Cu to the main catalyst can further reduce the generation of CH4.

[0071] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and inventive concept of this application, should be included within the scope of protection of this application.

Claims

1. A catalyst, characterized in that, Includes a carrier and an active component loaded on the carrier; The carrier is CeO2; The active components are Ir clusters and Cu atoms.

2. The catalyst according to claim 1, characterized in that, The mass fraction of the Ir cluster is 0.2% to 1.5%, and the mass fraction of the Cu atoms is 0.2% to 5%.

3. A method for preparing a catalyst, characterized in that, Includes the following steps: The support was mixed with an Ir source and a Cu source, and the reaction yielded a Cu-Ir / supported catalyst. The carrier is CeO2.

4. The preparation method according to claim 3, characterized in that, Specifically, it includes: The support was mixed with the Ir source, and the reaction yielded an Ir / supported catalyst. The Ir / supported catalyst was mixed with a Cu source, and the reaction yielded a Cu-Ir / supported catalyst.

5. The preparation method according to claim 3 or 4, characterized in that, The Ir source is chloroiridium acid.

6. The preparation method according to claim 3 or 4, characterized in that, The Cu source is copper nitrate trihydrate.

7. A method for reverse water-gas shift, characterized in that, Includes the following steps: After reducing the catalyst according to claim 1 or 2 or the catalyst prepared by any one of claims 3 to 6, the catalytic feed gas undergoes a reverse water-gas shift reaction. The raw materials are CO2 and H2.

8. The method according to claim 7, characterized in that, The reducing gas is H2; the gas space velocity of the reducing gas is 100 L / g / h to 500 L / g / h. The reduction temperature is 400℃~800℃, the heating rate is 5℃ / min~20℃ / min, and the reduction time is 0.5h~4h.

9. The method according to claim 7 or 8, characterized in that, The volume ratio of CO2:H2 in the raw gas is 1~8:

1.

10. The method according to claim 7 or 8, characterized in that, The reaction temperature is 500℃~700℃; The space velocity of the reaction is 30 L / g / h to 600 L / g / h.

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