A Zn / Cu modified Co-based catalyst, a preparation method and application thereof
By preparing a Zn/Cu-modified Co-based catalyst and using spinel MCo2O4 precursor and reduction treatment to form a Co-CoOx/MO structure, the problems of low-temperature conversion rate and high-temperature byproducts in carbon dioxide methanation catalysts were solved, achieving efficient and selective methane generation and carbon resource recycling.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHONGKE CARBON ENERGY TECHNOLOGY (DALIAN) CO LTD
- Filing Date
- 2025-10-20
- Publication Date
- 2026-07-14
AI Technical Summary
Existing carbon dioxide methanation catalysts suffer from problems such as high byproducts at high temperatures and low conversion rates at low temperatures. Precious metal catalysts are expensive, while transition metal catalysts have insufficient performance.
Using spinel MCo2O4 as a precursor, Co-based catalysts of Co-CoOx/MO and Co-based catalysts of Zn/Cu were obtained after reduction treatment. The interfacial charge distribution was regulated and the catalytic performance was improved by forming coordination bonds between the polar oxides of ZnO and CuO and Co-CoOx.
It achieves high carbon dioxide conversion rate and 100% methane selectivity at low temperatures, suppresses side reactions, adapts to industrial needs of different scales, and promotes the recycling of carbon resources.
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Figure CN121372408B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of catalyst technology, and in particular to a Zn / Cu modified Co-based catalyst, its preparation method, and its application. Background Technology
[0002] With the continuous development of industrialization and human activities, the concentration of carbon dioxide in the atmosphere has risen sharply, leading to global climate change and ecological degradation. As a major greenhouse gas, carbon dioxide emission reduction and resource utilization have become a global focus. Catalytic conversion of carbon dioxide into high-value-added chemicals (such as methane, methanol, and low-carbon olefins) not only helps alleviate the greenhouse effect but also enables the recycling of carbon resources and environmental remediation, meeting the strategic needs of sustainable development. In the carbon dioxide hydrogenation reaction, methane, as a clean energy carrier, has high energy density and broad application prospects. However, the chemical inertness of carbon dioxide and the complex intermediate products in the reaction process pose significant challenges to the development of efficient and highly selective catalysts. Currently, commonly used carbon dioxide methanation catalysts mainly include noble metals such as Ru and Pd, and transition metal catalysts. Among them, although noble metal catalysts exhibit excellent activity and selectivity, their high cost limits large-scale application. In contrast, transition metal catalysts have attracted much attention due to their higher abundance, lower cost, and good catalytic potential. However, transition metal catalysts still face challenges such as low carbon dioxide conversion rates at low temperatures and the easy generation of CO byproducts at high temperatures. Summary of the Invention
[0003] To address the shortcomings of existing technologies, this application provides a Zn / Cu modified Co-based catalyst, its preparation method, and its application. The catalyst is prepared by cutting spinel MCo₂O₄, which is then used as a precursor and reduced to obtain a Co-CoO₂ catalyst. x / MO Co-based catalysts, i.e., Zn / Cu modified Co-based catalysts, where M = Zn or Cu, CoO x Including CoO, Co2O3, and Co3O4. The Co-based catalyst prepared in this application exhibits extremely high carbon dioxide conversion rate and 100% methane selectivity, showing a significant performance improvement. Among them, metallic Co mainly plays the role of activating CO2 and H2, while CoO... x MO has a positive effect on the breaking of CO bonds, while it can modulate the Co-CoO bond. x The active pair; and the Zn / Cu modified Co-based catalyst prepared in this application shows a significant increase in carbon dioxide conversion rate at low temperatures.
[0004] To achieve the above objectives, this application adopts the following technical solution:
[0005] In a first aspect, this application provides a Zn / Cu modified Co-based catalyst, wherein the Zn / Cu modified Co-based catalyst is obtained by reduction treatment of spinel MCo2O4 as a precursor, and its composition is Co-CoO. x / MO, where M = Zn or Cu, CoO x Including CoO, Co2O3 and Co3O4.
[0006] In the Zn / Cu modified Co-based catalyst provided in this application, the spinel (MCo2O4) precursor has a highly ordered crystal structure and a stable framework, which can convert Zn... 2+ / Cu 2+ With Co 2+ / Co 3+ The uniform confinement within the crystal lattice lays the foundation for the formation of a uniform active component in the subsequent reduction process.
[0007] In the active structure obtained after reduction in this application, metallic Co can adsorb and activate H2, and CoO x It can adsorb and activate CO2, and the two work together to promote the hydrogenation reaction of CO2, significantly improving the conversion rate of carbon dioxide in the entire process of producing methane from carbon dioxide hydrogenation.
[0008] Furthermore, in the Zn / Cu modified Co-based catalyst provided in this application, both ZnO and CuO are polar oxides, and unsaturated O2 exists on their surfaces. 2- Ions that can react with Co-CoO x In active pairs, metallic Co forms coordination bonds (such as Co-O-Zn or Co-O-Cu). This coordination leads to a redistribution of charge at the interface. Therefore, MO(ZnO / CuO) can modulate the Co-CoO bond through interfacial charge polarization. x The electron density of the active pair is optimized to further enhance its adsorption and activation ability for reactant molecules, thereby improving its catalytic performance.
[0009] Secondly, this application provides a method for preparing a Zn / Cu modified Co-based catalyst, comprising the following steps:
[0010] Co(NO3)2 and M(NO3)2 were dissolved in deionized water, and then an alkaline precipitant was added. The pH was controlled at 7-9, and the mixture was stirred at 60-80℃ for 1-2 hours to obtain a cobalt-containing gel.
[0011] The cobalt-containing gel was placed in an oven and dried at 100-270℃ for 15-20 hours to obtain a cobalt-containing dried sample.
[0012] The cobalt-containing dried sample was then placed in a muffle furnace, heated to 400-700℃, and calcined for 2-8 hours to obtain MCo2O4.
[0013] MCo₂O₄ was placed in a reduction furnace, and a reducing gas was introduced. The furnace was heated to 300-500℃ and reacted for 1-4 hours to obtain a product with the composition Co-CoO₄. x / MO Co-based catalysts, i.e. Zn / Cu modified Co-based catalysts.
[0014] In one feasible implementation, the molar ratio of M(NO3)2 to Co(NO3)2 is 1:(2.1-2.3), where M = Zn or Cu.
[0015] In the preparation of the Zn / Cu modified Co-based catalyst, the amount of Co(NO3)2 used in this application is slightly excessive, which ensures that Zn... 2+ / Cu 2+ Completely embedded in the spinel lattice, avoiding Zn 2+ / Cu 2+ The ions do not participate in the reaction and form free ZnO / CuO impurities, thus avoiding problems such as free ZnO / CuO impurities occupying active sites or causing the aggregation of active components.
[0016] In one feasible implementation, the alkaline precipitant includes any one of ammonium carbamate, ammonia, and urea.
[0017] The alkaline precipitant used in this application can be converted into volatile substances such as H2O, CO2, and NH3 during subsequent calcination; and it will not introduce other metal ions into the obtained Zn / Cu modified Co-based catalyst.
[0018] In one feasible implementation, the cobalt-containing dried sample is heated at a rate of 1-10 °C / min in a muffle furnace.
[0019] The slower heating rate here allows all parts of the cobalt-containing dried sample to heat up synchronously, giving the various ions in the sample sufficient time to arrange themselves in an orderly manner, forming a complete and uniform spinel lattice structure, and avoiding local overheating that could lead to particle sintering.
[0020] In one feasible implementation, the flow rate of the reducing gas is 5-50 mL / min; the reducing gas includes a reducing component and an inert component; in the reducing gas, the volume fraction of the reducing component is 10%~50%, and the remainder is an inert component.
[0021] The controlled flow rate of the reducing gas here ensures sufficient reducing gas and stable temperature, guaranteeing a complete reduction reaction. The combination of reducing and inert components allows for regulation of the reduction rate, ensuring the optimal Co-CoO2 reaction. x The active sites are formed more uniformly.
[0022] In one feasible implementation, the reducing component includes any one or both of hydrogen and carbon monoxide; the inert component includes any one or both of nitrogen and argon.
[0023] In one feasible implementation, the heating rate of the reduction furnace is 1-20ºC / min.
[0024] The heating rate here allows the overall temperature of the MCo2O4 precursor to rise uniformly, and the reduction reaction proceeds simultaneously in all regions of the MCo2O4 precursor, gradually reducing it to Co-CoO. x Furthermore, the particles grow at a consistent rate, forming uniformly dispersed active sites, while avoiding structural breakage caused by thermal stress.
[0025] Thirdly, this application provides an application of a Zn / Cu modified Co-based catalyst in the hydrogenation of carbon dioxide to methane, comprising the following steps:
[0026] A Zn / Cu-modified Co-based catalyst is added to a reactor, and a mixture of hydrogen and carbon dioxide is introduced into the reactor at a flow rate of 5000-30000 mL / h under conditions of 100-700℃ and 0.1-10 MPa to produce methane.
[0027] In one feasible implementation, the molar ratio of hydrogen to carbon dioxide is (4-8):1.
[0028] Sufficient H2 here can promote the complete activation of CO2 and inhibit the formation of CO byproducts. At the same time, excess H2 can be combined with a gas flow rate of 5000-30000 mL / h to clean the surface of the prepared catalyst and reduce carbon deposition.
[0029] Beneficial technical effects:
[0030] This application obtains a Co-CoO composition by using spinel MCo2O4 as a precursor and performing a reduction treatment. x / MO Co-based catalysts, i.e., Zn / Cu modified Co-based catalysts, where M = Zn or Cu, CoO x These include CoO, Co2O3, and Co3O4. Among them, ZnO and CuO are both polar oxides, and their surfaces contain unsaturated O. 2- Ions that can react with Co-CoO x In active pairs, metallic Co forms coordination bonds (such as Co-O-Zn or Co-O-Cu). This coordination leads to a redistribution of charge at the interface. Therefore, MO(ZnO / CuO) can modulate the Co-CoO bond through interfacial charge polarization. xThe electron density of the active pairs is optimized to enhance their adsorption and activation capabilities for reactant molecules, thereby improving their catalytic performance. This application also achieves high purity and uniformity of the precursor by controlling various parameters during the preparation process, ensuring sufficient and well-dispersed active sites in the final catalyst, while avoiding impurity residues and structural defects. Ultimately, the Zn / Cu-modified Co-based catalyst prepared in this application can fully utilize its catalytic performance to promote efficient CO2 conversion and highly selectively generate methane, effectively suppressing side reactions. Furthermore, the reaction conditions are flexible and controllable, adapting to the needs of different scales of industrialization. This provides an efficient, stable, and industrially scalable technical solution for the resource utilization of carbon dioxide, helping to mitigate the greenhouse effect and achieve the recycling of carbon resources, showing great application potential in the field of environmental governance and remediation. Attached Figure Description
[0031] Figure 1 This is a photograph of the Zn / Cu-modified Co-based catalyst prepared in Example 1.
[0032] Figure 2 This is a schematic diagram of the preparation process of Zn / Cu modified Co-based catalysts. Detailed Implementation
[0033] To facilitate understanding of the content described in this application, the technical solutions described herein are further explained below with reference to specific embodiments; however, this application is not limited thereto. All equivalent transformations or simple substitutions made based on the substantive content of this application should fall within the protection scope of this application.
[0034] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.
[0035] The following will describe in detail, with reference to different embodiments, the preparation method of the Zn / Cu modified Co-based catalyst provided in this application, and its application in the hydrogenation of carbon dioxide to produce methane.
[0036] Example 1
[0037] like Figure 2 As shown, a method for preparing a Zn-modified Co-based catalyst includes the following steps:
[0038] 1. Dissolve Co(NO3)2 and Zn(NO3)2 in deionized water, then add alkaline precipitant ammonium carbamate, control the pH to 7, and stir at 60℃ for 1 h to obtain cobalt-containing gel;
[0039] In step 1, the molar ratio of Zn(NO3)2 to Co(NO3)2 is 1:2.1;
[0040] 2. Place the cobalt-containing gel in an oven and dry it at 100℃ for 20 hours to obtain a cobalt-containing dried sample;
[0041] 3. Subsequently, the cobalt-containing dried sample was placed in a muffle furnace and heated to 400℃ at a rate of 1℃ / min, and calcined for 8 hours to obtain ZnCo2O4;
[0042] 4. Place ZnCo2O4 in a reduction furnace and introduce reducing gas. Increase the temperature of the reduction furnace to 300℃ at a rate of 1℃ / min and react for 4 hours to obtain a product with the composition Co-CoO. x / ZnO Co-based catalysts, i.e. Zn-modified Co-based catalysts, wherein CoO x Including CoO, Co2O3, and Co3O4, their physical diagrams are as follows: Figure 1 As shown;
[0043] In step 4, the flow rate of the reducing gas is 5 mL / min; the reducing gas includes reducing component hydrogen and inert component nitrogen; the volume fraction of reducing component hydrogen is 10%, and the remainder is inert component nitrogen.
[0044] The prepared Zn-modified Co-based catalyst is used for the hydrogenation of carbon dioxide to produce methane, comprising the following steps:
[0045] A Zn-modified Co-based catalyst was added to a reactor. Under conditions of 700°C and 0.1 MPa, a mixture of hydrogen and carbon dioxide (molar ratio of hydrogen to carbon dioxide 4:1) was introduced into the reactor at a flow rate of 5000 mL / h, resulting in a reaction to produce methane. The carbon dioxide conversion rate of the Zn-modified Co-based catalyst prepared in this example was measured to be 71.2%, and the methane selectivity was 82.8%.
[0046] Example 2
[0047] like Figure 2 As shown, a method for preparing a Cu-modified Co-based catalyst includes the following steps:
[0048] 1. Dissolve Co(NO3)2 and Cu(NO3)2 in deionized water, then add alkaline precipitant ammonia water, control the pH to 8, and stir at 70℃ for 1.5h to obtain cobalt-containing gel;
[0049] In step 1, the molar ratio of Cu(NO3)2 to Co(NO3)2 is 1:2.2;
[0050] 2. Place the cobalt-containing gel in an oven and dry it at 180℃ for 17 hours to obtain a cobalt-containing dried sample;
[0051] 3. Subsequently, the cobalt-containing dried sample was placed in a muffle furnace and heated to 550°C at a rate of 5°C / min, and calcined for 5 hours to obtain CuCo2O4;
[0052] 4. Place CuCo2O4 in a reduction furnace and introduce reducing gas. Increase the temperature of the reduction furnace to 400℃ at a rate of 10℃ / min and react for 2.5 hours to obtain a product with the composition Co-CoO. x / CuO Co-based catalysts, i.e. Cu-modified Co-based catalysts, wherein CoO x Including CoO, Co2O3, and Co3O4;
[0053] In step 4, the flow rate of the reducing gas is 30 mL / min; the reducing gas includes the reducing component carbon monoxide and the inert component argon; the volume fraction of the reducing component carbon monoxide is 30%, and the remainder is the inert component argon.
[0054] The obtained Cu-modified Co-based catalyst is used for the hydrogenation of carbon dioxide to produce methane, comprising the following steps:
[0055] A Cu-modified Co-based catalyst was added to a reactor. Under conditions of 400°C and 5 MPa, a mixture of hydrogen and carbon dioxide (molar ratio of hydrogen to carbon dioxide 6:1) was introduced into the reactor at a flow rate of 10000 mL / h, resulting in a reaction to produce methane. The carbon dioxide conversion rate of the Cu-modified Co-based catalyst prepared in this example was measured to be 72.3%, and the methane selectivity was 85.4%.
[0056] Example 3
[0057] like Figure 2 As shown, a method for preparing a Zn-modified Co-based catalyst includes the following steps:
[0058] 1. Dissolve Co(NO3)2 and Zn(NO3)2 in deionized water, then add alkaline precipitant urea, control the pH to 9, and stir at 80℃ for 2 hours to obtain cobalt-containing gel;
[0059] In step 1, the molar ratio of Zn(NO3)2 to Co(NO3)2 is 1:2.3;
[0060] 2. Place the cobalt-containing gel in an oven and dry it at 270℃ for 15 hours to obtain a cobalt-containing dried sample;
[0061] 3. Subsequently, the cobalt-containing dried sample was placed in a muffle furnace and heated to 700°C at a rate of 10°C / min, and calcined for 2 hours to obtain ZnCo2O4;
[0062] 4. Place ZnCo2O4 in a reduction furnace and introduce reducing gas. Increase the temperature of the reduction furnace to 500℃ at a rate of 20℃ / min and react for 1 hour to obtain a product with the composition Co-CoO. x / ZnO Co-based catalysts, i.e. Zn-modified Co-based catalysts, wherein CoO x Including CoO, Co2O3, and Co3O4;
[0063] In step 4, the flow rate of the reducing gas is 50 mL / min; the reducing gas includes hydrogen and carbon monoxide in a reducing component volume ratio of 1:1 and nitrogen and argon in an inert component volume ratio of 1:1; the total volume fraction of hydrogen and carbon monoxide in a reducing component volume ratio of 1:1 is 50%, and the remainder is nitrogen and argon in an inert component volume ratio of 1:1.
[0064] The prepared Zn-modified Co-based catalyst is used for the hydrogenation of carbon dioxide to produce methane, comprising the following steps:
[0065] A Zn-modified Co-based catalyst was added to a reactor, and a mixture of hydrogen and carbon dioxide (molar ratio of hydrogen to carbon dioxide of 8:1) was introduced into the reactor at a flow rate of 30,000 mL / h under conditions of 100 °C and 10 MPa, resulting in a reaction to produce methane. The carbon dioxide conversion rate of the Zn-modified Co-based catalyst prepared in this example was measured to be 74.1%, and the methane selectivity was 89.2%.
[0066] Example 4
[0067] like Figure 2 As shown, a method for preparing a Cu-modified Co-based catalyst includes the following steps:
[0068] 1. Dissolve Co(NO3)2 and Cu(NO3)2 in deionized water, then add alkaline precipitant ammonium carbamate, control the pH to 7.5, and stir at 65℃ for 2 hours to obtain cobalt-containing gel;
[0069] In step 1, the molar ratio of Cu(NO3)2 to Co(NO3)2 is 1:2.1;
[0070] 2. Place the cobalt-containing gel in an oven and dry it at 160℃ for 16 hours to obtain a cobalt-containing dried sample;
[0071] 3. Subsequently, the cobalt-containing dried sample was placed in a muffle furnace and heated to 450°C at a rate of 3°C / min, and calcined for 6 hours to obtain CuCo2O4;
[0072] 4. Place CuCo2O4 in a reduction furnace and introduce reducing gas. Increase the temperature of the reduction furnace to 350℃ at a rate of 5℃ / min and react for 3 hours to obtain a product with the composition Co-CoO.x / CuO Co-based catalysts, i.e. Cu-modified Co-based catalysts, wherein CoO x Including CoO, Co2O3, and Co3O4;
[0073] In step 4, the flow rate of the reducing gas is 15 mL / min; the reducing gas includes reducing component hydrogen and inert component argon; the volume fraction of reducing component hydrogen is 20%, and the remainder is inert component argon.
[0074] The obtained Cu-modified Co-based catalyst is used for the hydrogenation of carbon dioxide to produce methane, comprising the following steps:
[0075] A Cu-modified Co-based catalyst was added to a reactor. Under conditions of 250°C and 8 MPa, a mixture of hydrogen and carbon dioxide (molar ratio of hydrogen to carbon dioxide 5:1) was introduced into the reactor at a flow rate of 12000 mL / h, resulting in a reaction to produce methane. The carbon dioxide conversion rate of the Cu-modified Co-based catalyst prepared in this example was measured to be 68.8%, and the methane selectivity was 80.3%.
[0076] Example 5
[0077] like Figure 2 As shown, a method for preparing a Zn-modified Co-based catalyst includes the following steps:
[0078] 1. Dissolve Co(NO3)2 and Zn(NO3)2 in deionized water, then add alkaline precipitant ammonia water, control the pH to 8.5, and stir at 75℃ for 1.5h to obtain cobalt-containing gel;
[0079] In step 1, the molar ratio of Zn(NO3)2 to Co(NO3)2 is 1:2.2;
[0080] 2. Place the cobalt-containing gel in an oven and dry it at 220℃ for 17 hours to obtain a cobalt-containing dried sample;
[0081] 3. Subsequently, the cobalt-containing dried sample was placed in a muffle furnace and heated to 600°C at a rate of 8°C / min, and calcined for 3 hours to obtain ZnCo2O4;
[0082] 4. Place ZnCo2O4 in a reduction furnace and introduce reducing gas. Increase the temperature of the reduction furnace to 450℃ at a rate of 15℃ / min and react for 2 hours to obtain a product with the composition Co-CoO. x / ZnO Co-based catalysts, i.e. Zn-modified Co-based catalysts, wherein CoO x Including CoO, Co2O3, and Co3O4;
[0083] In step 4, the flow rate of the reducing gas is 40 mL / min; the reducing gas includes the reducing component carbon monoxide and the inert component nitrogen; the volume fraction of the reducing component carbon monoxide is 40%, and the remainder is the inert component nitrogen.
[0084] The prepared Zn-modified Co-based catalyst is used for the hydrogenation of carbon dioxide to produce methane, comprising the following steps:
[0085] A Zn-modified Co-based catalyst was added to a reactor, and a mixture of hydrogen and carbon dioxide (molar ratio of hydrogen to carbon dioxide of 7:1) was introduced into the reactor at a flow rate of 20,000 mL / h under conditions of 550 °C and 2.5 MPa, resulting in a reaction to produce methane. The carbon dioxide conversion rate of the Zn-modified Co-based catalyst prepared in this example was measured to be 72.9%, and the methane selectivity was 86.1%.
[0086] Example 6
[0087] like Figure 2 As shown, a method for preparing a Cu-modified Co-based catalyst includes the following steps:
[0088] 1. Dissolve Co(NO3)2 and Cu(NO3)2 in deionized water, then add alkaline precipitant urea, control the pH to 8, and stir at 70℃ for 1.5h to obtain cobalt-containing gel;
[0089] In step 1, the molar ratio of Cu(NO3)2 to Co(NO3)2 is 1:2.3;
[0090] 2. Place the cobalt-containing gel in an oven and dry it at 200℃ for 18 hours to obtain a cobalt-containing dried sample;
[0091] 3. Subsequently, the cobalt-containing dried sample was placed in a muffle furnace and heated to 600°C at a rate of 6°C / min, and calcined for 4 hours to obtain CuCo2O4;
[0092] 4. Place CuCo2O4 in a reduction furnace and introduce reducing gas. Increase the temperature of the reduction furnace to 400℃ at a rate of 12℃ / min and react for 2.5 hours to obtain a product with the composition Co-CoO. x / CuO Co-based catalysts, i.e. Cu-modified Co-based catalysts, wherein CoO x Including CoO, Co2O3, and Co3O4;
[0093] In step 4, the flow rate of the reducing gas is 15 mL / min; the reducing gas includes hydrogen and carbon monoxide in a reducing component volume ratio of 1:1 and argon in an inert component volume ratio of 1:1; the volume fraction of hydrogen and carbon monoxide in the reducing component volume ratio of 1:1 is 30%, and the remainder is argon in an inert component volume ratio.
[0094] The obtained Cu-modified Co-based catalyst is used for the hydrogenation of carbon dioxide to produce methane, comprising the following steps:
[0095] A Cu-modified Co-based catalyst was added to a reactor. Under conditions of 300°C and 7 MPa, a mixture of hydrogen and carbon dioxide (molar ratio of hydrogen to carbon dioxide 6.5:1) was introduced into the reactor at a flow rate of 15000 mL / h, resulting in the production of methane. The carbon dioxide conversion rate of the Cu-modified Co-based catalyst prepared in this example was measured to be 73.4%, and the methane selectivity was 87.5%.
[0096] Comparative Example 1
[0097] A method for preparing a Co-based catalyst includes the following steps:
[0098] 1. Dissolve Co(NO3)2 in deionized water, then add alkaline precipitant ammonium carbamate, control the pH to 7, and stir at 60℃ for 1 h to obtain cobalt-containing gel;
[0099] 2. Place the cobalt-containing gel in an oven and dry it at 100℃ for 20 hours to obtain a cobalt-containing dried sample;
[0100] 3. Subsequently, the cobalt-containing dried sample was placed in a muffle furnace and heated to 400°C at a rate of 1°C / min, and calcined for 8 hours to obtain the calcined product;
[0101] 4. Place the calcined product in a reduction furnace and introduce reducing gas. Heat the reduction furnace to 300℃ at a rate of 1℃ / min and react for 4 hours to obtain a Co-based catalyst.
[0102] In step 4, the flow rate of the reducing gas is 5 mL / min; the reducing gas includes reducing component hydrogen and inert component nitrogen; the volume fraction of reducing component hydrogen is 10%, and the remainder is inert component nitrogen.
[0103] The prepared Co-based catalyst is used for the hydrogenation of carbon dioxide to produce methane, comprising the following steps:
[0104] The prepared Co-based catalyst was added to a reactor, and a mixture of hydrogen and carbon dioxide (molar ratio of hydrogen to carbon dioxide of 4:1) was introduced into the reactor at a flow rate of 5000 mL / h under conditions of 700 °C and 0.1 MPa, resulting in a reaction to produce methane. The carbon dioxide conversion rate of the Co-based catalyst prepared in this comparative example was measured to be 29.7%, and the methane selectivity was 32.3%.
[0105] Comparative Example 2
[0106] A method for preparing a Zn-modified Co-based catalyst includes the following steps:
[0107] 1. Dissolve Co(NO3)2 and Zn(NO3)2 in deionized water, then add alkaline precipitant urea, control the pH to 9, and stir at 80℃ for 2 hours to obtain cobalt-containing gel;
[0108] In step 1, the molar ratio of Zn(NO3)2 to Co(NO3)2 is 1:2.3;
[0109] 2. Place the cobalt-containing gel in an oven and dry it at 270℃ for 15 hours to obtain a cobalt-containing dried sample;
[0110] 3. Place the cobalt-containing dry sample in a reduction furnace and introduce reducing gas. Increase the temperature of the reduction furnace to 500℃ at a rate of 20℃ / min and react for 1 hour to obtain a Zn-modified Co-based catalyst, wherein CoO... x Including CoO, Co2O3, and Co3O4;
[0111] In step 3, the flow rate of the reducing gas is 50 mL / min; the reducing gas includes hydrogen and carbon monoxide in a reducing component volume ratio of 1:1 and nitrogen and argon in an inert component volume ratio of 1:1; the total volume fraction of hydrogen and carbon monoxide in a reducing component volume ratio of 1:1 is 50%, and the remainder is nitrogen and argon in an inert component volume ratio of 1:1.
[0112] The prepared Zn-modified Co-based catalyst is used for the hydrogenation of carbon dioxide to produce methane, comprising the following steps:
[0113] The prepared Zn-modified Co-based catalyst was added to a reactor. A mixture of hydrogen and carbon dioxide (molar ratio of hydrogen to carbon dioxide 8:1) was introduced into the reactor at a flow rate of 30,000 mL / h under conditions of 100 °C and 10 MPa, resulting in a reaction to produce methane. The carbon dioxide conversion rate of the Zn-modified Co-based catalyst prepared in this comparative example was measured to be 41.6%, and the methane selectivity was 43.1%.
[0114] Comparative Example 3
[0115] A method for preparing a Cu-modified Co-based catalyst includes the following steps:
[0116] 1. Dissolve Co(NO3)2 and Cu(NO3)2 in deionized water, then add alkaline precipitant urea, control the pH to 8, and stir at 70℃ for 1.5h to obtain cobalt-containing gel;
[0117] In step 1, the molar ratio of Cu(NO3)2 to Co(NO3)2 is 1:2.3;
[0118] 2. Place the cobalt-containing gel in an oven and dry it at 200℃ for 18 hours to obtain a cobalt-containing dried sample;
[0119] 3. Subsequently, the cobalt-containing dried sample was placed in a muffle furnace and heated to 600°C at a rate of 6°C / min, and calcined for 4 hours to obtain CuCo2O4;
[0120] 4. Place CuCo2O4 in a reduction furnace and introduce argon gas. Heat the reduction furnace to 400℃ at a rate of 12℃ / min and maintain the temperature for 2.5h to obtain a Co-based catalyst with composite Cu.
[0121] In step 4, the argon gas flow rate is 15 mL / min.
[0122] The prepared Cu-based catalyst is used for the hydrogenation of carbon dioxide to produce methane, comprising the following steps:
[0123] The prepared Co-based catalyst of composite Cu was added to a reactor. Under conditions of 300℃ and 7 MPa, a mixture of hydrogen and carbon dioxide (molar ratio of hydrogen to carbon dioxide 6.5:1) was introduced into the reactor at a flow rate of 15000 mL / h, resulting in the production of methane. The carbon dioxide conversion rate of the Co-based catalyst of composite Cu prepared in this comparative example was measured to be 14.3%, and the methane selectivity was 12.7%.
[0124] The test results of the Co-based catalysts prepared in each embodiment and comparative example are shown in Table 1.
[0125] Table 1. Test results of the Co-based catalysts prepared in Examples 1-6 and Comparative Examples 1-3
[0126] Carbon dioxide conversion rate (%) Methane selectivity (%) Example 1 71.2 82.8 Example 2 72.3 85.4 Example 3 74.1 89.2 Example 4 68.8 80.3 Example 5 72.9 86.1 Example 6 73.4 87.5 Comparative Example 1 29.7 32.3 Comparative Example 2 41.6 43.1 Comparative Example 3 14.3 12.7
[0127] As shown in Table 1, the carbon dioxide conversion rate and methane selectivity of Examples 1-6 are generally higher than those of Comparative Examples 1-3.
[0128] The main reason is that in Examples 1-6, spinel MCo2O4 was used as a precursor, and after reduction treatment, a Co-CoO composition was obtained. x / MO Co-based catalysts, i.e., Zn / Cu modified Co-based catalysts, where M = Zn or Cu, CoO x These include CoO, Co2O3, and Co3O4. Among them, ZnO and CuO are both polar oxides, and their surfaces contain unsaturated O. 2- Ions that can react with Co-CoO xIn active pairs, metallic Co forms coordination bonds (such as Co-O-Zn or Co-O-Cu). This coordination leads to a redistribution of charge at the interface. Therefore, MO(ZnO / CuO) can modulate the Co-CoO bond through interfacial charge polarization. x The electron density of the active pairs is optimized to enhance their adsorption and activation capabilities for reactant molecules, thereby improving their catalytic performance. This application also achieves high purity and uniformity of the precursor by controlling various parameters during the preparation process, ensuring sufficient and well-dispersed active sites in the final catalyst, while avoiding impurity residues and structural defects. Ultimately, the Zn / Cu-modified Co-based catalyst prepared in this application can fully utilize its catalytic performance to promote efficient CO2 conversion and highly selectively generate methane, effectively suppressing side reactions. Furthermore, the reaction conditions are flexible and controllable, adapting to the needs of different scale industrial applications, and it has enormous application potential in the field of environmental remediation.
[0129] In contrast, in Comparative Example 1, no Zn / Cu was introduced to modify the Co-based catalyst during its preparation, thus failing to produce a Co-CoO composition. x / MO Co-based catalysts, and there is no ZnO and CuO regulating Co-CoO x The electron density of the active pairs is reduced, which prevents them from optimizing their adsorption and activation capabilities for reactant molecules, ultimately resulting in a significant decrease in both carbon dioxide conversion and methane selectivity.
[0130] In Comparative Example 2, the cobalt-containing dried sample was not further calcined, thus failing to obtain a spinel-structured precursor. Although subsequent reduction of the cobalt-containing dried sample in a reduction furnace also had some calcination effect, the parameters differed from those used to prepare the spinel-structured precursor. Ultimately, it was impossible to obtain a Zn / Cu-modified Co-based catalyst with sufficient and well-dispersed active sites while avoiding impurity residues and structural defects. Consequently, its carbon dioxide conversion and methane selectivity decreased.
[0131] In Comparative Example 3, after the obtained CuCo2O4 was added to the reduction furnace, argon gas was introduced instead of a reducing gas. Therefore, CuCo2O4 could not be reduced smoothly, and the Co-CoO composition could not be obtained. x The Co-based catalyst of / CuO has the worst carbon dioxide conversion and methane selectivity.
[0132] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.
[0133] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.
Claims
1. A Zn / Cu modified Co-based catalyst, characterized in that, The Zn / Cu modified Co-based catalyst was obtained by reduction treatment of spinel MCo2O4, and its composition was Co-CoO. x / MO, where M = Zn or Cu, CoO x Including CoO, Co2O3, and Co3O4; The preparation method of the Zn / Cu modified Co-based catalyst includes the following steps: Co(NO3)2 and M(NO3)2 were dissolved in deionized water, and then an alkaline precipitant was added. The pH was controlled at 7-9, and the mixture was stirred at 60-80℃ for 1-2 hours to obtain a cobalt-containing gel. The cobalt-containing gel was placed in an oven and dried at 100-270℃ for 15-20 hours to obtain a cobalt-containing dried sample. The cobalt-containing dried sample was then placed in a muffle furnace, heated to 400-700℃, and calcined for 2-8 hours to obtain MCo2O4. MCo₂O₄ was placed in a reduction furnace, and a reducing gas was introduced. The furnace was heated to 300-500℃ and reacted for 1-4 hours to obtain a product with the composition Co-CoO₄. x / MO Co-based catalysts, i.e. Zn / Cu modified Co-based catalysts; The molar ratio of M(NO3)2 to Co(NO3)2 is 1:(2.1-2.3). The alkaline precipitant includes any one of ammonium carbamate, ammonia, and urea.
2. The Zn / Cu-modified Co-based catalyst according to claim 1, characterized in that, The heating rate of the cobalt-containing dried sample in the muffle furnace was 1-10 °C / min.
3. The Zn / Cu-modified Co-based catalyst according to claim 1, characterized in that, The flow rate of the reducing gas is 5-50 mL / min; the reducing gas includes a reducing component and an inert component; the volume fraction of the reducing component in the reducing gas is 10%~50%, and the remainder is an inert component.
4. The Zn / Cu-modified Co-based catalyst according to claim 3, characterized in that, The reducing component includes any one or both of hydrogen and carbon monoxide; the inert component includes any one or both of nitrogen and argon.
5. The Zn / Cu-modified Co-based catalyst according to claim 1, characterized in that, The heating rate of the reduction furnace is 1-20ºC / min.
6. The application of a Zn / Cu modified Co-based catalyst in the hydrogenation of carbon dioxide to methane, characterized in that, Includes the following steps: The Zn / Cu modified Co-based catalyst of claim 1 is added to a reactor, and a mixture of hydrogen and carbon dioxide is introduced into the reactor at a flow rate of 5000-30000 mL / h under the conditions of a temperature of 100-700℃ and a pressure of 0.1-10 MPa to produce methane.
7. The application of the Zn / Cu-modified Co-based catalyst according to claim 6 in the hydrogenation of carbon dioxide to methane, characterized in that, The molar ratio of hydrogen to carbon dioxide is (4-8):1.