A copper-based catalyst with a limited field effect and a preparation method and application thereof
By anchoring copper ions at the edges and corners of the hydrotalcite lattice, a copper ion-based hydrotalcite catalyst was constructed, solving the problems of uneven dispersion of Cu-ZnO-Al2O3 catalyst and insufficient thermal stability of hydrotalcite, thus achieving a highly efficient CO2 to methanol conversion reaction.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-27
- Publication Date
- 2026-06-30
AI Technical Summary
Existing Cu-ZnO-Al2O3 catalysts suffer from uneven dispersion of active components and poor stability during the CO2 to methanol conversion process. Furthermore, traditional hydrotalcite catalysts have insufficient thermal stability and their layered structures are prone to collapse.
Copper ions are anchored at the edges and corners of the hydrotalcite lattice using an ion exchange method to construct a copper ion-based hydrotalcite catalyst. A multi-component hydrotalcite precursor is formed through a co-precipitation method, and inactive components are introduced in a specific order to form a layered structure, which restricts the migration and aggregation of active centers and improves the stability of the catalyst.
This approach achieves high methanol yield and good thermal stability of the catalyst, avoids excessive growth of catalyst particles, and improves the catalyst's lifespan and activity.
Smart Images
Figure CN122298419A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a copper-based catalyst with confinement effect, its preparation method and application, belonging to the field of catalyst preparation technology. Background Technology
[0002] The reduction of CO2 to CH3OH is generally considered the foundation of the "methanol economy." Since 2012, a demonstration plant in Iceland has been using a heterogeneous Cu-ZnO catalyst to produce approximately 4,000 tons of methanol annually from CO2 and H2, thus recovering 5,500 tons of CO2 annually. In 2020, Energy-X's report, "Research Needs for Sustainable Production of Fuels and Chemicals," noted that Germany and China are developing other industrial facilities for converting CO2 to methanol. Catalysts for producing methanol from CO2 include thermocatalysis, photocatalysis, electrocatalysis, and biocatalysis.
[0003] The synthesis of methanol from CO2 and H2 is an exothermic reaction. The conversion of CO2 to methanol is kinetically limited at low temperatures and thermodynamically limited at high temperatures, resulting in a theoretical methanol yield as low as 0.06% at 300℃ and 0.1 MPa. In typical industrial methanol synthesis, the reactants are CO, H2, and a small amount of CO2, reacting on a Cu-ZnO-Al2O3 catalyst under conditions of 220–300℃ and 5–10 MPa. Cu-ZnO-Al2O3 has also been studied for the synthesis of methanol from CO2 and H2, but the methanol selectivity and yield are not ideal. Furthermore, Cu-based catalysts gradually deactivate during the reaction, and the methanol synthesis catalyzed by these catalysts is a structure-sensitive reaction; the catalyst activity is related to the specific surface area, dispersibility, structural composition, and electronic properties of Cu. Currently, the most mature methanol catalysts are copper-based catalysts, represented by the copper-zinc-aluminum system, which are industrially prepared by co-precipitation. Although the preparation method is simple and easy, a common problem with co-precipitation is the uneven dispersion of the active component, leading to decreased catalyst stability after high-temperature reaction. Therefore, the key to methanol catalysts is to improve the dispersion of the catalyst and limit the migration and aggregation of active species in a simple and easy industrial manner.
[0004] Hydrotalcite has attracted widespread attention in recent years due to its tunable structure and ease of design. Its chemical composition can be represented as [M... 2+ 1-x M 3+ x (OH)2] x+ [(A n- ) x / n ·mH2O] x- M 2+ Mg 2+ Ni 2+ Co 2+ Zn2+ Cu 2+ Divalent metal cations; M 3+ For Al 3+ Cr 3+ Fe 3+ ,Sc 3+ Isovalent trivalent metal cations; A n- It is an anion, such as CO3. 2- NO 3- Cl - OH - SO4 2- PO4 3- C6H4(COO)2 2- Inorganic and organic ions, as well as complexed ions, are present. Because hydrotalcite materials do not have a fixed chemical composition, the elemental types and proportions of their main layers, the types and quantities of interlayer anions, and the two-dimensional pore structure can be adjusted over a wide range as needed, thereby obtaining materials with special structures and properties. The tunability of the composition and structure of LDHs and the resulting multifunctionality are significant. Conventional catalysts utilize their interlayer structure to stabilize the active components, but the thermal stability of this method is insufficient for long-term catalytic reactions; furthermore, the pure hydrotalcite layered structure is prone to collapse. Summary of the Invention
[0005] To address the shortcomings or improvement needs of existing technologies, this invention provides a copper-based catalyst with confinement effect for the catalytic conversion of CO2-rich materials into methanol. This catalyst uses hydrotalcite as a precursor and employs an ion exchange method to anchor copper ions at the edges and corners of the hydrotalcite lattice, achieving a high methanol yield without significant growth in catalyst particles before and after the reaction.
[0006] The specific technical solution of this invention is as follows:
[0007] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0008] S1 involves immersing the raw materials in a solvent and stirring to react;
[0009] S2. Filter, dry, and calcine the slurry obtained in step S1 to obtain the catalyst.
[0010] The raw materials include hydrotalcite precursors and copper salts;
[0011] The hydrotalcite precursor includes at least one divalent metal;
[0012] Preferably, the hydrotalcite precursor includes metal salt 1 and metal salt 2;
[0013] The metal salt 1 includes one of zinc salt, magnesium salt, lanthanum salt, cerium salt, zirconium salt, and manganese salt;
[0014] The metal salt 2 includes aluminum salts;
[0015] The solvent includes one of the following: sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium dodecyl sulfate, and disodium ethylenediaminetetraacetate.
[0016] This invention employs an ion exchange method to replace divalent metal ions in the hydrotalcite precursor with copper ions, constructing a copper-ion-based hydrotalcite catalyst. This allows for precise design of copper active sites, and due to the high accessibility of the corner sites in the hydrotalcite configuration, copper ions can be anchored at these sites. Figure 1 It can be seen that the crystal structure characteristics of the catalyst, such as grain size and cell parameters, have changed, and the grain growth direction has also been adjusted. The metal ions are closely arranged, forming a strong metal-to-metal interaction, which restricts the migration and aggregation of active centers, prevents copper particles from growing excessively before and after the reaction, and ensures the stability of the catalyst.
[0017] Preferably, the metal salt 1 and metal salt 2 are added in a metal ion molar ratio of 1:2 to 2:1.
[0018] The copper salt and metal salt 1 are added in a metal ion molar ratio of 5:1 to 1:5.
[0019] Preferably, the method for preparing the hydrotalcite precursor includes the following steps:
[0020] The precipitant solution, metal salt 1 solution, and metal salt 2 solution are stirred and reacted; aged; after centrifugation, the lower precipitate is washed and dried to obtain the final product.
[0021] This invention uses a co-precipitation method to construct a hydrotalcite precursor, forming a layered structure by combining the cations and anions of inactive components (cations refer to metal cations, and anions refer to anions in the precipitant) in a specific order.
[0022] Furthermore,
[0023] The precipitant includes at least one of sodium hydroxide, sodium bicarbonate, potassium hydroxide, and ammonia.
[0024] Furthermore, the stirring reaction conditions are: 60–70°C, pH = 9–10;
[0025] And / or, the aging conditions are: aging at 60-70°C for 6-10 hours.
[0026] Preferably, the reaction conditions for step S1 are continuous stirring at 60–80°C for 12–24 hours.
[0027] Preferably, the calcination conditions in step S2 are calcination at 300–450°C for at least 4 hours.
[0028] Another objective of this invention is to protect the application of the copper-based methanol catalyst with confinement effect prepared by the above preparation method in the catalytic conversion of CO2 to methanol.
[0029] Preferably, a reduction process is performed before application;
[0030] And / or, the conditions for the catalytic conversion of CO2 to methanol are: synthesis gas, at a temperature of 200–300℃, a pressure of 4.0–8.0 MPa, and a space velocity of 5000–20000 h⁻¹. -1 Reactions under certain conditions.
[0031] Preferably, the reduction treatment conditions are: temperature 200-300℃; pressure: atmospheric pressure; atmosphere: H2 / N2 mixture, H2 volume fraction 3-8%; reduction overnight.
[0032] The beneficial effects of this invention are at least as follows:
[0033] This invention employs a co-precipitation method to construct a multi-component hydrotalcite precursor, in which the cations and anions of the inactive components are arranged in a specific order to form a layered structure. Based on this, an ion exchange method is used to replace the divalent metal ions in the multi-component hydrotalcite precursor with copper ions to construct a copper ion-based hydrotalcite catalyst, thereby improving the collapse of the layered structure and enhancing the stability of the catalyst. Attached Figure Description
[0034] Figure 1 The XRD patterns of the catalysts in Example 3 and Comparative Examples 1-5 are shown below.
[0035] Figure 2 The images show the H2-TPR spectra of the catalysts in Example 3 and Comparative Example 1. Detailed Implementation
[0036] The following specific examples are only used to further illustrate the technical solution of the present invention, and the effects of the method of the present invention are not limited thereto.
[0037] Unless otherwise specified in the examples, the solution is an aqueous solution.
[0038] Example 1
[0039] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0040] (1) Preparation of MgAl binary hydrotalcite precursor by coprecipitation method: Prepare a 0.5 mol / L NaOH and NaHCO3 aqueous solution (molar ratio 1:1) denoted as A; weigh 7.42 g magnesium nitrate and 10.65 g aluminum nitrate and dissolve them in 100 mL of aqueous solution denoted as B; in a stirred tank at 60 °C, add the above solution A and solution B dropwise in parallel, and continuously stir the reaction to control the pH to be maintained at around 9; age the resulting slurry at 70 °C for 6 hours, centrifuge and wash the lower precipitate with deionized water until the pH of the supernatant is 7-8; dry the precipitate at 120 °C overnight to obtain the binary hydrotalcite precursor.
[0041] (2) Ion exchange between Cu and MgAl binary hydrotalcite precursor: Prepare a 0.5 mol / L sodium dodecylbenzenesulfonate aqueous solution, weigh 1.88 g of copper nitrate and the binary hydrotalcite precursor obtained in (1) and immerse them in the sodium dodecylbenzenesulfonate solution, and stir continuously at 60 °C for 24 hours; filter, dry at 120 °C overnight, and calcine at 350 °C for 4 hours to obtain the catalyst.
[0042] Example 2
[0043] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0044] (1) Preparation of MgAl binary hydrotalcite precursor by coprecipitation method: Prepare a 0.5 mol / L NaOH and NaHCO3 aqueous solution (molar ratio 1:1) denoted as A; weigh 7.42 g magnesium nitrate and 10.65 g aluminum nitrate and dissolve them in 100 mL of aqueous solution denoted as B; in a stirred tank at 70 °C, add the above solution A and solution B dropwise in parallel, and continuously stir the reaction to control the pH to be maintained at around 10; age the resulting slurry at 60 °C for 10 hours, centrifuge and wash the lower precipitate with deionized water until the pH of the supernatant is 7-8; dry the precipitate at 120 °C overnight to obtain the binary hydrotalcite precursor.
[0045] (2) Ion exchange between Cu and MgAl binary hydrotalcite precursor: Prepare a 0.5 mol / L sodium dodecylbenzenesulfonate solution, weigh 3.75 g of copper nitrate and the binary hydrotalcite precursor obtained in (1) and immerse them in the sodium dodecylbenzenesulfonate solution, and stir continuously at 80 °C for 12 hours; filter, dry at 120 °C overnight, and calcine at 350 °C for 4 hours to obtain the catalyst.
[0046] Example 3
[0047] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0048] (1) Preparation of MgAl binary hydrotalcite precursor by coprecipitation method: Prepare a 0.5 mol / L NaOH and NaHCO3 aqueous solution (molar ratio 1:1) denoted as A; weigh 7.42 g magnesium nitrate and 10.65 g aluminum nitrate and dissolve them in 100 mL of aqueous solution denoted as B; in a stirred tank at 65 °C, add the above solution A and solution B dropwise in parallel, and continuously stir the reaction to control the pH to be maintained at about 9.5; age the resulting slurry at 65 °C for 8 hours, centrifuge and wash the lower precipitate with deionized water until the pH of the supernatant is 7-8; dry the precipitate at 120 °C overnight to obtain the binary hydrotalcite precursor and the catalyst.
[0049] (2) Ion exchange between Cu and MgAl binary hydrotalcite precursor: Prepare a 0.5 mol / L sodium dodecylbenzenesulfonate solution, weigh 5.63 g of copper nitrate and the binary hydrotalcite precursor obtained in (1) and immerse them in the sodium dodecylbenzenesulfonate solution, and stir continuously at 70 °C for 18 hours; filter, dry at 120 °C overnight, and calcine at 350 °C for 4 hours to obtain the catalyst.
[0050] Example 4
[0051] A method for preparing a copper-based catalyst with confinement effect includes the following steps: The preparation method of the catalyst is the same as in Example 3, except that the amount of copper nitrate added is 7.50g.
[0052] Example 5
[0053] A method for preparing a copper-based catalyst with confinement effect includes the following steps: The preparation method of the catalyst is the same as in Example 3, except that the amount of copper nitrate added is 9.38g.
[0054] Example 6
[0055] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0056] The catalyst was prepared according to Example 3, except that the 0.5 mol / L sodium dodecylbenzenesulfonate solution in step (2) of Example 3 was replaced with a 0.5 mol / L sodium lauryl sulfate solution.
[0057] Example 7
[0058] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0059] The catalyst was prepared according to Example 3, except that the 0.5 mol / L sodium dodecylbenzenesulfonate solution in step (2) of Example 3 was replaced with a 0.5 mol / L sodium dodecyl sulfate solution.
[0060] Example 8
[0061] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0062] The catalyst was prepared according to Example 3, except that the 0.5 mol / L sodium dodecylbenzenesulfonate solution in step (2) of Example 3 was replaced with a 0.5 mol / L disodium ethylenediaminetetraacetate solution.
[0063] Example 9
[0064] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0065] The catalyst was prepared according to Example 3, except that the 7.42g magnesium nitrate in step (1) of Example 3 was replaced with 10.65g zinc nitrate.
[0066] Example 10
[0067] A method for preparing a copper-based catalyst with confinement effect includes the following steps: The catalyst preparation method is the same as in Example 3, except that the amount of copper nitrate added is 15g.
[0068] Comparative Example 1
[0069] A method for preparing Cu3Mg5Al5 catalyst by coprecipitation includes the following steps:
[0070] Prepare a 0.5 mol / L aqueous solution of NaOH and NaHCO3 (molar ratio 1:1), denoted as A; weigh out 5.63 g of copper nitrate, 7.42 g of magnesium nitrate, and 10.65 g of aluminum nitrate and dissolve them in 100 mL of aqueous solution, denoted as B; in a stirred tank at 65 °C, simultaneously add the above solutions A and B dropwise, continuously stirring the reaction to maintain the pH at around 9.5; age the resulting slurry at 65 °C for 8 hours, centrifuge, and wash the lower precipitate with deionized water until the pH of the supernatant is 7-8; dry the precipitate at 120 °C overnight and calcine at 350 °C for 4 hours.
[0071] Comparative Example 2
[0072] A method for preparing a copper-based catalyst with confinement effect includes the following steps: The preparation method of the catalyst is the same as in Example 3, except that the 0.5 mol / L sodium dodecylbenzenesulfonate solution in step (2) of Example 3 is replaced with a 5 mol / L sodium dodecylbenzenesulfonate solution.
[0073] Comparative Example 3
[0074] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0075] The catalyst was prepared according to Example 3, except that the 0.5 mol / L sodium dodecylbenzenesulfonate solution in step (2) of Example 3 was replaced with water.
[0076] Comparative Example 4
[0077] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0078] The catalyst was prepared according to Example 3, except that the 0.5 mol / L sodium dodecylbenzenesulfonate solution in step (2) of Example 3 was replaced with an ethanol solution.
[0079] Comparative Example 5
[0080] A method for preparing a copper-based catalyst with a confinement effect includes the following steps:
[0081] The catalyst was prepared according to Example 3, except that the 0.5 mol / L sodium dodecylbenzenesulfonate solution in step (2) of Example 3 was replaced with a 0.5 mol / L citric acid solution.
[0082] Implementation Results Example
[0083] Activity testing conditions: The catalyst loading in the fixed-bed reactor was 4 mL. The catalyst was pre-reduced overnight at 250℃, atmospheric pressure, and 5 vol% H2-N2. After converting the gas to N2, the reactor was purged, and the reaction pressure was increased to 5.0 MPa while maintaining the temperature at 250℃. After purging for 1 hour, the gas was converted to syngas with the following composition: 15% CO2, 5% CO, 10% N2, and 70% H2. The reaction was then carried out at 250℃, 5.0 MPa, and a space velocity of 10000 h⁻¹. -1 The activity of CO2-rich catalytic conversion to methanol was evaluated under the specified conditions.
[0084] Stability test: The catalysts prepared in Examples 1-8 and Comparative Example 1 were heat-treated at 400°C for 5 hours and then cooled to 250°C for evaluation.
[0085] The activity evaluation results are shown in Table 1:
[0086] Table 1: Activity Evaluation Results
[0087]
[0088] Analysis of Examples 1-5 and 10 shows that the amount of copper is suitable within a reasonable range; the copper content in Example 10 is high, but the exchangeable Mg content is low. 2+ The amount is less than Cu 2+This is equivalent to the precipitation formation of a bulk catalyst. Within a certain range, the higher the copper content, the better the catalyst activity, but its stability is poor. Therefore, the addition amount of copper salt and metal salt 1 is limited to a metal ion molar ratio of 5:1 to 1:5. In Example 9, with Cu... 2+ What was exchanged was Zn 2+ It can also achieve good spatiotemporal yield and good thermal stability.
[0089] Analysis of Examples 3, 6-8, and Comparative Example 2 shows that the solvent has a significant effect on ion exchange, with sodium dodecylbenzenesulfonate showing the best effect. Furthermore, a higher solvent concentration is not necessarily better. Comparative Examples 3-5 show the results with water, ethanol, and citric acid aqueous solution as solvents, indicating that the effects were not good. Comparative Example 1 used a co-precipitation method; different preparation methods result in different catalyst structures, and the catalyst in Comparative Example 1 exhibited poor performance and stability.
[0090] The XRD patterns of the catalysts in Example 3 and Comparative Examples 1-5 are as follows: Figure 1 As shown in the comparison, it was found that the XRD in Example 3 did not show any CuO characteristic peaks, indicating that Cu... 2+ Ions enter the hydrotalcite structure without additional CuO crystals. The hydrotalcite diffraction peaks in Example 3 are sharper and have higher intensity, indicating that the preparation method in Example 3 is superior to the coprecipitation method in the comparative example, resulting in better crystallinity.
[0091] The H2-TPR diagrams of the catalysts in Example 3 and Comparative Example 1 are shown in the figure. The reduction temperature of Example 3 is lower, indicating that the material is easier to reduce, which in turn indicates that the interaction between the components is stronger.
[0092] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.
Claims
1. A method for preparing a copper-based catalyst with confinement effect, characterized in that, Includes the following steps: S1 involves immersing the raw materials, including hydrotalcite precursor and copper salt, in a solvent and stirring to react; S2. Filter, dry, and calcine the slurry obtained in step S1 to obtain the catalyst. The hydrotalcite precursor includes at least one divalent metal; Preferably, the hydrotalcite precursor includes metal salt 1 and metal salt 2; The metal salt 1 includes at least one of zinc salt, magnesium salt, lanthanum salt, cerium salt, zirconium salt, and manganese salt; The metal salt 2 includes aluminum salts; The solvent includes at least one of the following: sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium dodecyl sulfate, and disodium ethylenediaminetetraacetate.
2. The method for preparing the copper-based catalyst with confinement effect as described in claim 1, characterized in that, The amounts of metal salt 1 and metal salt 2 added are in a metal ion molar ratio of 1:2 to 2:
1. And / or, the amount of copper salt and metal salt 1 added is in the form of a metal ion molar ratio of 5:1 to 1:
5.
3. The method for preparing the copper-based catalyst with confinement effect as described in claim 1 or 2, characterized in that, The method for preparing the hydrotalcite precursor includes the following steps: obtaining a mixture of precipitant, metal salt 1, and metal salt 2, stirring and reacting; aging; washing and drying the lower precipitate after centrifugation to obtain the precursor.
4. The method for preparing the copper-based catalyst with confinement effect as described in claim 3, characterized in that, The precipitant includes at least one of sodium hydroxide, sodium bicarbonate, potassium hydroxide, and ammonia.
5. The method for preparing the copper-based catalyst with confinement effect as described in claim 3 or 4, characterized in that, The stirring reaction conditions are: 60-70℃, pH = 9-10; And / or, the aging conditions are: aging at 60-70°C for 6-10 hours.
6. The method for preparing the copper-based catalyst with confinement effect as described in any one of claims 1-5, characterized in that, The reaction conditions for step S1 are continuous stirring at 60–80°C for 12–24 hours.
7. The method for preparing the copper-based catalyst with confinement effect as described in any one of claims 1-6, characterized in that, The calcination conditions for step S2 are 300-450℃ for 4-6 hours.
8. The application of the copper-based catalyst with confinement effect prepared by any of the preparation methods described in claims 1-7 in the catalytic conversion of CO2 to methanol.
9. The application as described in claim 8, characterized in that, Before application, the catalyst is subjected to a reduction treatment; And / or, the conditions for the catalytic conversion of CO2 to methanol are: synthesis gas at a temperature of 200–300℃, a pressure of 4.0–8.0 MPa, and a space velocity of 5000–20000 h⁻¹. -1 Reactions under certain conditions.
10. The application as described in claim 9, characterized in that, The conditions for the reduction treatment include: temperature 200–300°C; pressure at atmospheric pressure; atmosphere of H2 / N2 mixture, with H2 volume fraction of 3–8%.