Confined range catalyst as well as preparation method and application thereof
The confined catalyst prepared by the sol-gel method solves the problems of poor catalytic activity and complicated preparation in the existing technology, and realizes the catalytic hydrogenation reaction of carbon dioxide with high conversion rate and selectivity, which is suitable for industrial application.
Patent Information
- Application Number
- CN202511834165.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-08
- Publication Date
- 2026-03-06
AI Technical Summary
Existing catalysts exhibit poor catalytic activity in the catalytic hydrogenation of carbon dioxide, making it difficult to achieve high conversion rates and high selectivity. Furthermore, their preparation methods are complex and costly, hindering their industrial application.
Confined catalysts were prepared using the sol-gel method. By introducing confining structure building agents, catalysts with both molecular and mesoporous pore structures were formed. The catalysts included a matrix, active components, and promoters, and the metal loading and spatial confinement effect were optimized.
It significantly improves the catalytic performance and stability of the catalyst, achieves high conversion and selectivity under high metal loading, simplifies the preparation process, and is suitable for large-scale and industrial applications.
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Figure CN121607151A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of catalysis, and more specifically to a confined catalyst with a unique mesoporous-microporous structure and a method for preparing the same, and also to a catalytic reaction method for producing methanol by hydrogenation of carbon dioxide using the catalyst. Background Technology
[0002] Catalytic hydrogenation of carbon dioxide is an environmentally friendly and economical strategy for carbon recycling and the sustainable production of high-value-added chemicals such as methanol, which is crucial for alleviating the energy crisis and achieving carbon neutrality. However, in this process, CO2, as a reactant, has considerable chemical inertness, and controlling side reactions is also quite difficult. Therefore, achieving a high conversion rate of CO2 and converting it to the target product (e.g., methanol) with high selectivity is a very challenging task. Extensive research has been conducted on this topic, but satisfactory results have yet to be achieved.
[0003] For example, some studies have used metal oxide-organic ligand composites with nanoporous structures (such as PCN-type materials) as supports, on which active metals are loaded / doped. However, the carbon dioxide conversion and methanol selectivity achieved by such catalysts are low (carbon dioxide conversion below 8%, methanol selectivity less than 55%), far from reaching industrial-scale levels. Other studies have explored using molecular sieve materials such as MCM-41 and SBA-15 as supports, impregnating and loading various transition metals onto the molecular sieve supports to prepare supported catalysts. The results showed that while this type of catalyst could slightly improve methanol selectivity, the carbon dioxide conversion rate was significantly reduced (only 3.2%). There are also reports of using silica-based molecular sieves (such as MFI-type molecular sieves) as supports, on which various transition metals and noble metal components are loaded, but the improvement in carbon dioxide conversion and methanol selectivity is also quite limited.
[0004] The catalysts described above all suffer from limited support pore capacity, severely restricting the loading of the active metal component. The loading of the active metal in the catalyst is typically less than 3% by mass, resulting in poor catalytic activity and making it difficult to simultaneously achieve high conversion and high selectivity. Furthermore, existing confined catalyst preparation methods usually involve multiple complex steps, such as first synthesizing a porous support and then impregnating and loading the active metal component onto the support. These methods are cumbersome, costly, and difficult to scale up for industrial application. Therefore, there is an urgent need in the field to develop a novel catalyst design strategy that can balance high metal loading and good spatial confinement effects, while simultaneously achieving high activity, high selectivity, and excellent stability. Summary of the Invention
[0005] To address the above problems, the first aspect of this application provides a method for preparing a confined catalyst, the method comprising:
[0006] Step 1: Prepare a mixture of matrix precursor, active ingredient precursor, adjuvant precursor and water;
[0007] Step 2: Add the confined structure building agent to the mixture to form a mixed raw material;
[0008] Step 3: Add a complexing agent and a pH adjuster to the mixed raw materials, and then heat at a first temperature to form a gel;
[0009] Step 4: Heat-treat the gel to form the confined catalyst.
[0010] According to one embodiment of the first aspect of this application, in step one, the matrix precursor is selected from one or more of the following: a water-soluble salt of aluminum, a water-soluble salt or ester of titanium, a water-soluble salt of cerium, a water-soluble salt of niobium, and a water-soluble salt of indium; the active component precursor is a water-soluble salt of copper; and the auxiliary agent precursor is a water-soluble salt of one or more of the following elements: zinc, molybdenum, gold, cobalt, lanthanum, and gallium.
[0011] According to another embodiment of the first aspect of this application, in step one, the molar ratio of the active component precursor to the matrix precursor is 10:1 to 1:5.
[0012] According to another embodiment of the first aspect of this application, in step one, the molar ratio of the adjuvant precursor to the matrix precursor is 6:1 to 1:3.
[0013] According to another embodiment of the first aspect of this application, in step two, the confined structure building agent is selected from one or more of the following: benzene, biphenyl, aromatic hydrocarbons containing two or more fused benzene rings, and may optionally be substituted by one or more substituents selected from the following: C1-C12 alkyl, hydroxyl, carboxyl, amino, chlorine, bromine, iodine.
[0014] According to another embodiment of the first aspect of this application, in step two, the molar ratio of the confined structure building agent to the matrix precursor is 1:10 to 5:1.
[0015] According to another embodiment of the first aspect of this application, in step two, the confined structure building agent is dissolved in an organic solvent to form an organic solution, and then the organic solution is added to the mixture obtained in step one. The organic solvent is selected from one or more of the following: methanol, ethanol, acetonitrile, acetone, dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, N-ethylpyrrolidone, 1-butylpyrrolidone, dimethylacetamide, and tetrahydrofuran.
[0016] According to another embodiment of the first aspect of this application, in step three, the complexing agent is selected from one or more of the following: citric acid, oxalic acid, tartaric acid, ethylenediaminetetraacetic acid, aminotriacetic acid, amino acids, gluconic acid, stearic acid, and ethylenediamine.
[0017] According to another embodiment of the first aspect of this application, in step three, the molar ratio of the matrix precursor to the complexing agent is 2:1 to 1:50.
[0018] According to another embodiment of the first aspect of this application, in step three, the pH adjuster is selected from one or more of the following: ammonia, urea, ammonium carbonate, ammonium bicarbonate, urea, formamide, ethylenediamine; the pH value of the mixed raw materials is adjusted to 5-9 using the pH adjuster.
[0019] According to another embodiment of the first aspect of this application, in step three, heating is performed at a first temperature of 30-150°C for 1-12 hours to form a gel.
[0020] According to another embodiment of the first aspect of this application, in step four, drying is carried out at a second temperature of 50-150°C for 1-24 hours.
[0021] According to another embodiment of the first aspect of this application, in step four, calcination is carried out at a third temperature of 200-700°C for 1-12 hours, and the calcination adopts a heating rate of 0.1-5°C / min.
[0022] A second aspect of this application provides a confined catalyst comprising a matrix, an active component, and an additive, wherein the matrix has a mesoporous structure and comprises oxides of one or more elements selected from the group consisting of aluminum, zirconium, titanium, cerium, niobium, and indium.
[0023] The active component includes copper oxide;
[0024] The additive comprises oxides of one or more elements selected from the following: zinc, molybdenum, gold, cobalt, lanthanum, gallium;
[0025] The confined catalyst also contains a microporous structure.
[0026] According to one embodiment of the second aspect of this application, the confined catalyst comprises, based on the total mass of the catalyst, 35-60% by mass of matrix, 20-60% by mass of active component, and 1-40% by mass of auxiliaries.
[0027] According to another embodiment of the second aspect of this application, the confined catalyst is prepared by the method described in any embodiment of the first aspect of this application.
[0028] A third aspect of this application provides a catalytic reaction method comprising reacting carbon dioxide with hydrogen in the presence of the confined catalyst described above to produce methanol.
[0029] According to one embodiment of the third aspect of this application, the reaction temperature of the catalytic reaction is 180-250°C and the reaction pressure is 1-6 MPa.
[0030] In the detailed embodiments section below, the method and composite adsorbent of this application will be further described with reference to the accompanying drawings. Attached Figure Description
[0031] Figure 1 A schematic diagram of a catalyst preparation method according to one embodiment of this application is shown;
[0032] Figure 2 Figure A shows the nitrogen adsorption / desorption of catalyst A prepared according to an embodiment of this application;
[0033] Figure 2 B shows a micropore size distribution diagram of catalyst A prepared according to an embodiment of this application;
[0034] Figure 2 C shows a mesopore size distribution diagram of catalyst A prepared according to an embodiment of this application;
[0035] Figure 3 Figure A shows the nitrogen adsorption / desorption of catalyst a prepared according to a comparative example of this application;
[0036] Figure 3 B shows a mesopore size distribution of catalyst a prepared according to a comparative example of this application. Detailed Implementation
[0037] The “range” disclosed in this document takes the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges that can be defined in this way are inclusive and composable; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if the minimum range values are listed as 1 and 2, and if the maximum range values are listed as 3, 4, and 5, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.
[0038] In this application, unless otherwise stated, the numerical range "ab" is a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in this document, and "0-5" is simply a shortened representation of these numerical combinations.
[0039] Unless otherwise specified in this application, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.
[0040] Unless otherwise specified, all technical features and preferred features mentioned herein can be combined to form new technical solutions.
[0041] In this application, unless otherwise specified, the term "comprising" as used herein can be either open-ended or closed-ended. For example, "comprising" may mean that it may also include other components not listed, or it may only include the listed components.
[0042] One inventive aspect of this invention is that the method of this invention enables the synthesis of the confined catalyst of this invention in a simple, mild, and low-cost manner, and this method is particularly suitable for large-scale and industrial applications.
[0043] The catalyst synthesis method of this invention employs the sol-gel method, introducing a confined structure building agent during the catalyst synthesis process, thereby forming a confined catalyst possessing both molecular-level and mesoporous pore structures. In this invention, the structure formed based on the confined structure building agent is a molecular-level pore structure, also referred to as a "microporous structure," which represents a microporous structure with a pore size less than 2 nanometers, preferably 0.3-0.9 nanometers. The "mesoporous pore structure" or "mesoporous structure" described in this invention is generated by the sol-gel method, and its pore size ranges from 2-50 nanometers, preferably 2-20 nanometers, and more preferably, most (e.g., greater than 50%, or greater than 80%, or greater than 90%) of the mesoporous structure has a pore size of 2-15 nanometers.
[0044] The catalyst synthesized by this invention simultaneously comprises the aforementioned "microporous structure" and "mesoporous structure." These two different-sized microstructures establish a unique confined structure in the catalyst of this invention, that is, constructing a confined environment for the catalytic reaction at the nanoscale to regulate and improve catalytic reaction performance. The inventors unexpectedly discovered that the catalyst synthesis method of this invention can produce catalysts with a unique microporous confinement + mesoporous structure, significantly improving the loading content of various active metal elements, thereby improving the catalytic performance of the catalyst, and effectively maintaining its stability during long-term reactions.
[0045] The catalyst preparation method of the present invention includes the following steps:
[0046] Step 1: Prepare a mixture of matrix precursor, active ingredient precursor, adjuvant precursor and water;
[0047] Step 2: Add the confined structure building agent to the mixture to form a mixed raw material;
[0048] Step 3: Add a complexing agent and a pH adjuster to the mixed raw materials, and then heat at a first temperature to form a gel;
[0049] Step 4: Heat-treat the gel to form the confined catalyst.
[0050] like Figure 1 As shown, in step one, the matrix precursor includes one or more of the following: a water-soluble salt of aluminum, a water-soluble salt of zirconium, a water-soluble salt or ester of titanium, a water-soluble salt of cerium, a water-soluble salt of niobium, or a water-soluble salt of indium; preferably, the matrix precursor includes a water-soluble salt of aluminum or a water-soluble salt of zirconium, or both. The active component precursor includes a water-soluble salt of copper. The auxiliary agent precursor includes a water-soluble salt of one or more of the following metal elements: zinc, molybdenum, gold, cobalt, lanthanum, or gallium; preferably, the auxiliary agent precursor includes a water-soluble salt of zinc, or simultaneously contains a water-soluble salt of zinc and a water-soluble salt of lanthanum, or simultaneously contains a water-soluble salt of zinc and a water-soluble salt of gallium. In the case where the auxiliary agent precursor simultaneously contains a water-soluble salt of zinc and a water-soluble salt of lanthanum, the molar ratio of zinc to lanthanum is 3:1 to 1:2, preferably 2:1 to 1:1, and more preferably 5:4. When the additive precursor contains both a water-soluble salt of zinc and a water-soluble salt of gallium, the molar ratio of zinc to gallium is 10:1 to 1:1, preferably 8:1 to 3:1, and more preferably 6:1 to 4:1.
[0051] According to another embodiment of this application, the water-soluble salts of the various precursors include nitrates, chlorides, sulfates, phosphates, formates, acetates, oxalates, citrates, methanesulfonates, p-toluenesulfonates, etc.; the water-soluble esters of the various precursors may include C1-C6 alkyl esters of metal acids, such as tetramethyl titanate, tetraethyl titanate, tetraisopropyl titanate, tetran-n-butyl titanate, etc. Alternatively, an aqueous solution of the above-mentioned water-soluble salts can be prepared by dissolving insoluble compounds such as oxides, hydroxides, and bicarbonates of the corresponding metals using appropriate acids (e.g., nitric acid, hydrochloric acid, sulfuric acid, etc.).
[0052] According to one embodiment of this application, the mixture prepared in step one is in the form of an aqueous solution or a hydrosol, wherein the concentrations of the matrix precursor, active component precursor and auxiliary agent precursor mentioned above are 0.1-8 mol / L, preferably 0.2-6 mol / L, more preferably 0.3-5 mol / L, and most preferably 0.5-1.5 mol / L.
[0053] According to another embodiment of this application, in step one, the molar ratio of the active component precursor to the matrix precursor is 10:1 to 1:5, preferably 8:1 to 1:2, more preferably 7:1 to 1:1, for example 5:1, 6:1, 5:3.
[0054] According to another embodiment of this application, in step one, the molar ratio of the adjuvant precursor to the matrix precursor is 6:1 to 1:3, preferably 5:1 to 1:2, more preferably 3:1 to 2:3, for example 2:1, 2:3, 2.7:1, 1.77:1.
[0055] According to another embodiment of this application, the water used in this invention may include distilled water, desalinated water, ultrapure water, ion-exchange water, or deionized water; preferably, it is deionized water.
[0056] According to a specific embodiment of this application, step one is carried out in the following manner: the matrix precursor, the auxiliary agent precursor, the active component precursor and water are mixed together and stirred at 0-60°C, preferably 15-40°C, more preferably room temperature for 0.1-4 hours, more preferably 0.2-2 hours, and most preferably 0.5-1 hours.
[0057] Next, in step two, the confined structure (microporous structure) building agent is dissolved in an organic solvent to form an organic solution. Then, the organic solution is added to the solution or sol prepared in step one, and the resulting mixture is stirred to ensure thorough mixing.
[0058] According to one embodiment of this application, the confined structure building agent is a compound containing a benzene ring, which may include one or more of the following: benzene, biphenyl, aromatic hydrocarbons containing two or more fused benzene rings (e.g., naphthalene, anthracene, etc.), and may optionally be substituted by one or more (e.g., one, two, three, four, five or six) substituents selected from the following: C1-C12 alkyl, hydroxyl, carboxyl, amino, chlorine, bromine, iodine. According to an exemplary embodiment of this application, the confined structure building agent includes one or more of the following: benzene, toluene, ethylbenzene, phenol, bromobenzene, aniline, o-xylene, m-xylene, p-xylene, hydroquinone, terephthalic acid, naphthalene, anthracene; preferably, the confined structure building agent is benzene, naphthalene, phenol, or terephthalic acid.
[0059] According to another embodiment of this application, the organic solvent used in step two is preferably a water-soluble organic solvent, such as one or more selected from the following: methanol, ethanol, acetonitrile, acetone, dimethyl sulfoxide, dimethylformamide, N-methylpyrrolidone, N-ethylpyrrolidone, 1-butylpyrrolidone, dimethylacetamide, and tetrahydrofuran. Preferably, the organic solvent is dimethyl sulfoxide, tetrahydrofuran, N-methylpyrrolidone, or dimethylformamide.
[0060] According to another embodiment of this application, the concentration of the confined structure building agent in the organic solution is 0.1-5 mol / L, for example 0.2-3 mol / L, preferably 0.5-2 mol / L, more preferably 0.6-1.5 mol / L, and most preferably 0.9-1.2 mol / L.
[0061] According to another embodiment of this application, in step two, after adding the organic solution to the solution or sol prepared in step one, the mixture is stirred at a temperature of 0-60°C (preferably 10-40°C, more preferably room temperature) for 0.2-8 hours, more preferably 0.3-4 hours, and most preferably 0.5-1 hours.
[0062] According to another embodiment of this application, the molar ratio of the confined structure building agent added in step two to the matrix precursor added in step one is 1:5 to 10:1, or 1:2 to 8:1, or 1:1 to 6:1, or 2:1 to 4:1, or 3:1 to 4:1, for example 5:1, 1.1:1, 3.3:1, 3.4:1.
[0063] In step three, a complexing agent and a pH adjuster are added to the mixed raw materials, and then the mixture is heated at a first temperature to form a gel. The complexing agent can be added directly to the mixture obtained in step two in bulk (solid) form.
[0064] The complexing agent is selected from one or more of the following: citric acid, oxalic acid, tartaric acid, ethylenediaminetetraacetic acid, aminotriacetic acid, amino acids, gluconic acid, stearic acid, ethylenediamine; preferably, the complexing agent is oxalic acid, citric acid, or tartaric acid.
[0065] According to one embodiment of this application, the molar ratio of the matrix precursor added in step one to the complexing agent added in step three is 2:1 to 1:50, or 1:1 to 1:40, or 1:10 to 1:30, for example 1:10, 1:15, 1:20, 1:25, 1:30.
[0066] In step three, the pH adjuster is selected from one or more of the following: ammonia, urea, ammonium carbonate, ammonium bicarbonate, urea, formamide, and ethylenediamine. The pH of the mixed raw materials is adjusted to 5-9, preferably 6-8.5, and more preferably 7-8, using the pH adjuster.
[0067] In step three, the heating temperature for the sol-gelation treatment is 30-150℃, preferably 40-120℃, more preferably 60-100℃, and most preferably 80-90℃. In step three, the sol-gelation process continues for 1-12 hours, preferably 2-10 hours, more preferably 3-8 hours, and most preferably 5-6 hours.
[0068] In step three, the mixture first forms a uniform sol, and then the water gradually evaporates as the temperature rises, gradually transforming into a gel.
[0069] According to one embodiment of this application, step three is carried out under continuous stirring, with a stirring speed of 100-500 rpm, more preferably 150-400 rpm, and most preferably 250-350 rpm.
[0070] Step four includes drying and calcining the gel obtained in step three. Drying includes heating at a temperature of 50-150°C for 1-24 hours, for example, the drying temperature can be 60-120°C, preferably 75-110°C; the drying duration is preferably 5-20 hours, more preferably 9-15 hours. The calcination temperature is 200-700°C, more preferably 300-600°C, and most preferably 300-450°C; the calcination time is 1-12 hours, more preferably 3-8 hours, and most preferably 4-6 hours. According to one embodiment of this application, the heating rate of calcination in step four is 0.1-5°C / min, more preferably 0.5-5°C / min, and most preferably 1-2°C / min.
[0071] In the above sol-gel process, metal elements (especially metal elements in the matrix) are assembled into mesoporous channel structures in the form of oxides, while confined structure building agents are bound in the oxides constituting the mesoporous structures. Subsequently, in step four, the confined structure building agents (containing benzene ring organic compounds) are removed, and the space originally occupied by them will form a unique microporous structure, thereby giving the catalyst of the present invention a unique mesoporous-microporous confined structure.
[0072] Unwilling to be confined by specific theories, the inventors believe that the catalyst prepared in this invention constructs a unique hierarchical pore structure of "microporous confinement units embedded in a mesoporous matrix," where mesopores are responsible for macroscopic mass transfer, and micropores provide a molecular confinement environment, thus resolving the contradiction between diffusion limitation and confinement effect. By dispersing multiple microporous confinement units in the overall catalyst, high dispersion is achieved under high overall metal loading, breaking through the loading limitations of traditional confined catalysts. Directly constructing microporous units in a metal oxide matrix avoids complex multi-step preparation processes, improving preparation efficiency and structural stability.
[0073] The composition of various components in the catalyst prepared by this invention is determined by the proportion of raw materials added by the above method. According to one embodiment of this application, based on the total mass of the catalyst, the catalyst contains 35-60% by mass of matrix, for example 40-58% by mass, or 45-55% by mass, or 50-54% by mass; the catalyst contains 20-60% by mass of active component, for example 22-50% by mass, or 23-40% by mass, or 25-30% by mass; the catalyst contains 1-40% by mass of promoter, for example 3-35% by mass, or 5-30% by mass, or 10-25% by mass, or 15-24% by mass.
[0074] The catalyst comprises a structure consisting of metal oxides derived from the aforementioned precursors (mesoporous channels and microporous structures as described above). The active metal oxide and auxiliary metal oxide are dispersed in the unique structure of the catalyst. Organic compounds such as confined structure builders and complexing agents added during the preparation process are removed during calcination.
[0075] The catalyst of this invention can be used in the catalytic hydrogenation of carbon dioxide to produce methanol. The reaction temperature is 180-250°C, for example 200-240°C, or 210-230°C, most preferably 220-225°C; the reaction pressure is 1-6 MPa (provided by carbon dioxide and hydrogen), for example 2-5 MPa, or 3-4 MPa. The volume ratio of hydrogen to carbon dioxide in the reaction system is 5:1 to 1:1, for example 4:1 to 2:1, preferably 3:1.
[0076] According to another embodiment of this application, the total space velocity of the carbon dioxide and hydrogen can be 1000-8000 mL / g / hour, for example 2000-5000 mL / g / hour, preferably 3000-4000 mL / g / hour.
[0077] The following embodiments illustrate the methods of this application in detail, with the aim of providing a better understanding of the content of this application. It should be understood that these embodiments are merely illustrative and not restrictive. Unless otherwise stated, the reagents used in the embodiments are commercially available analytical grade reagents. Unless otherwise specified, the methods and conditions used in the embodiments are conventional methods and conditions.
[0078] Example
[0079] The water used in the following examples is deionized water, and all other reagents are analytical grade, purchased from the market, and used directly without further treatment.
[0080] Example 1
[0081] In this embodiment, the catalyst was first prepared according to the following steps:
[0082] First, weigh 14.5 g of Cu(NO3)2·3H2O, 5.9 g of Zn(NO3)2·6H2O, and 7.5 g of Al(NO3)3·9H2O, dissolve them in 200 mL of deionized water, and stir at room temperature for 30 min to obtain a homogeneous and transparent aqueous solution. Separately, weigh 5.5 g of terephthalic acid, dissolve it in 20 mL of dimethyl sulfoxide, and add the resulting organic solution to the above aqueous solution. Continue stirring at room temperature for 30 min. Add 31.5 g of citric acid monohydrate to the above materials, then adjust the pH of the materials to 7 using ammonia water, raise the temperature to 90°C, and continue stirring for 6 hours to obtain a gel. Transfer the gel to an oven and dry it at 110°C for 12 hours to obtain a dry gel. Place the obtained dry gel in a muffle furnace and heat it to 450°C at a heating rate of 1°C / min, calcining it at this temperature for 6 hours. The resulting catalyst is designated as catalyst A.
[0083] The catalyst prepared in this example was characterized by nitrogen adsorption-desorption, and the measured nitrogen adsorption-desorption curves are shown below. Figure 2 As shown in Figure A, this confirms that the catalyst possesses both mesoporous and microporous structures, as shown in Figure A. Figure 2 As shown in B and 2C, the catalyst prepared in this embodiment therefore has a unique mesoporous-microporous (confined) structure.
[0084] Using the catalyst prepared in this embodiment, a catalytic reaction for the catalytic hydrogenation of carbon dioxide to methanol was carried out in a fixed-bed reactor at a reaction pressure of 3.0 MPa, a temperature of 220 °C, a space velocity of 3000 mL / g / h, and an H2 / CO2 volume ratio of 3. The results are summarized in Table 1 below. After 100 hours of continuous catalytic reaction, the carbon dioxide conversion rate and methanol selectivity decreased by no more than 5%.
[0085] Example 2
[0086] In this embodiment, the catalyst was first prepared according to the following steps:
[0087] First, weigh 12.1 g of Cu(NO3)2·3H2O, 5.9 g of Zn(NO3)2·6H2O, and 12.9 g of Zr(NO3)4·5H2O, and dissolve them in 200 mL of deionized water. Stir at room temperature for 30 min to obtain a homogeneous and transparent aqueous solution. Separately, weigh 3.1 g of phenol and dissolve it in 20 mL of dimethyl sulfoxide. Add the resulting organic solution to the above aqueous solution and continue stirring at room temperature for 30 min. Add 27.0 g of oxalic acid to the above materials, then adjust the pH of the materials to 7 using ammonia water. Raise the temperature to 90 °C and continue stirring for 6 hours to obtain a gel. Transfer the gel to an oven and dry it at 110 °C for 12 hours to obtain a dry gel. Place the obtained dry gel in a muffle furnace and heat it to 450 °C at a heating rate of 1 °C / min, and calcine it at this temperature for 6 hours. The resulting catalyst is designated as catalyst B.
[0088] The catalyst prepared in this example was characterized by nitrogen adsorption-desorption, which confirmed that the catalyst possesses both mesoporous and microporous structures. Therefore, the catalyst prepared in this example has a unique mesoporous-microporous (confined) structure.
[0089] Using the catalyst prepared in this embodiment, a catalytic reaction for the catalytic hydrogenation of carbon dioxide to methanol was carried out in a fixed-bed reactor at a reaction pressure of 3.0 MPa, a temperature of 220 °C, a space velocity of 3000 mL / g / h, and an H2 / CO2 volume ratio of 3. The results are summarized in Table 1 below. After 100 hours of continuous catalytic reaction, the carbon dioxide conversion rate and methanol selectivity decreased by no more than 5%.
[0090] Example 3
[0091] In this embodiment, the catalyst was first prepared according to the following steps:
[0092] First, weigh 14.5 g of Cu(NO3)2·3H2O, 5.9 g of Zn(NO3)2·6H2O, and 7.5 g of Al(NO3)3·9H2O, dissolve them in 200 mL of deionized water, and stir at room temperature for 30 min to obtain a homogeneous and transparent aqueous solution. Separately, weigh 2.6 g of benzene, dissolve it in 30 mL of tetrahydrofuran, and add the resulting organic solution to the above aqueous solution. Continue stirring at room temperature for 45 min. Add 27.0 g of oxalic acid to the above mixture, then adjust the pH to 8 using ammonium carbonate, raise the temperature to 90 °C, and continue stirring for 5 hours to obtain a gel. Transfer the gel to an oven and dry it at 110 °C for 10 hours to obtain a dry gel. Place the obtained dry gel in a muffle furnace and heat it to 350 °C at a rate of 1 °C / min, calcining it at this temperature for 6 hours. The resulting catalyst is designated as catalyst C.
[0093] The catalyst prepared in this example was characterized by nitrogen adsorption-desorption, which confirmed that the catalyst possesses both mesoporous and microporous structures. Therefore, the catalyst prepared in this example has a unique mesoporous-microporous (confined) structure.
[0094] Using the catalyst prepared in this embodiment, a catalytic reaction for the catalytic hydrogenation of carbon dioxide to methanol was carried out in a fixed-bed reactor at a reaction pressure of 3.0 MPa, a temperature of 220 °C, a space velocity of 3000 mL / g / h, and an H2 / CO2 volume ratio of 3. The results are summarized in Table 1 below. After 100 hours of continuous catalytic reaction, the carbon dioxide conversion rate and methanol selectivity decreased by no more than 5%.
[0095] Example 4
[0096] In this embodiment, the catalyst was first prepared according to the following steps:
[0097] First, weigh 14.5 g of Cu(NO3)2·3H2O, 4.5 g of Zn(NO3)2·6H2O, 5.1 g of La(NO3)3·6H2O, and 7.5 g of Al(NO3)3·9H2O, and dissolve them in 200 mL of deionized water. Stir at room temperature for 45 min to obtain a homogeneous and transparent aqueous solution. Separately, weigh 6.4 g of naphthalene and dissolve it in 30 mL of N-methylpyrrolidone. Add the resulting organic solution to the above aqueous solution and continue stirring at room temperature for 1 hour. Add 37.5 g of tartaric acid to the above materials, then adjust the pH of the materials to 7 using urea. Raise the temperature to 80 °C and continue stirring for 6 hours to obtain a gel. Transfer the gel to an oven and dry it at 90 °C for 12 hours to obtain a dry gel. Place the obtained dry gel in a muffle furnace and heat it to 400 °C at a heating rate of 1 °C / min. Calcinate at this temperature for 5 hours. The resulting catalyst is denoted as catalyst D.
[0098] The catalyst prepared in this example was characterized by nitrogen adsorption-desorption, which confirmed that the catalyst possesses both mesoporous and microporous structures. Therefore, the catalyst prepared in this example has a unique mesoporous-microporous (confined) structure.
[0099] Using the catalyst prepared in this embodiment, a catalytic reaction for the catalytic hydrogenation of carbon dioxide to methanol was carried out in a fixed-bed reactor at a reaction pressure of 3.0 MPa, a temperature of 220 °C, a space velocity of 3000 mL / g / h, and an H2 / CO2 volume ratio of 3. The results are summarized in Table 1 below. After 100 hours of continuous catalytic reaction, the carbon dioxide conversion rate and methanol selectivity decreased by no more than 5%.
[0100] Example 5
[0101] In this embodiment, the catalyst was first prepared according to the following steps:
[0102] First, weigh 12.1 g of Cu(NO3)2·3H2O, 4.5 g of Zn(NO3)2·6H2O, 0.7 g of Ga(NO3)3, and 7.5 g of Al(NO3)3·9H2O, and dissolve them in 200 mL of deionized water. Stir at room temperature for 30 min to obtain a homogeneous and transparent aqueous solution. Separately, weigh 4.4 g of naphthalene and dissolve it in 30 mL of dimethylformamide. Add the resulting organic solution to the above aqueous solution and continue stirring at room temperature for 30 min. Add 42.0 g of citric acid monohydrate to the above materials, then adjust the pH of the materials to 8 using ammonia water, raise the temperature to 90°C, and continue stirring for 6 hours to obtain a gel. Transfer the gel to an oven and dry it at 110°C for 12 hours to obtain a dry gel. Place the obtained dry gel in a muffle furnace and heat it to 450°C at a heating rate of 1°C / min, and calcine it at this temperature for 6 hours. The resulting catalyst is denoted as catalyst E.
[0103] The catalyst prepared in this example was characterized by nitrogen adsorption-desorption, which confirmed that the catalyst possesses both mesoporous and microporous structures. Therefore, the catalyst prepared in this example has a unique mesoporous-microporous (confined) structure.
[0104] Using the catalyst prepared in this embodiment, a catalytic reaction for the catalytic hydrogenation of carbon dioxide to methanol was carried out in a fixed-bed reactor at a reaction pressure of 3.0 MPa, a temperature of 220 °C, a space velocity of 3000 mL / g / h, and an H2 / CO2 volume ratio of 3. The results are summarized in Table 1 below. After 100 hours of continuous catalytic reaction, the carbon dioxide conversion rate and methanol selectivity decreased by no more than 5%.
[0105] Comparative Example 1
[0106] In this comparative example, the catalyst was first prepared according to the following steps:
[0107] First, weigh 14.5 g of Cu(NO3)2·3H2O, 5.9 g of Zn(NO3)2·6H2O, and 7.5 g of Al(NO3)3·9H2O, dissolve them in 200 mL of deionized water, and stir at room temperature for 30 min to obtain a homogeneous and transparent aqueous solution. Add 31.5 g of citric acid monohydrate to the above aqueous solution, then adjust the pH of the material to 7 using ammonia water, raise the temperature to 90℃, and continue stirring for 6 hours to obtain a gel. Transfer the gel to an oven and dry it at 110℃ for 12 hours to obtain a dry gel. Place the obtained dry gel in a muffle furnace and heat it to 450℃ at a heating rate of 1℃ / min, and calcine it at this temperature for 6 hours. The resulting catalyst is denoted as catalyst a.
[0108] The catalyst prepared in this example was characterized by nitrogen adsorption-desorption, and the measured nitrogen adsorption-desorption curves are shown below. Figure 3 As shown in Figure A, this confirms that catalyst a possesses only a mesoporous structure and lacks a microporous structure, as shown in Figure A. Figure 3 As shown in B.
[0109] Catalytic hydrogenation of carbon dioxide to methanol was carried out in a fixed-bed reactor using catalyst a at a pressure of 3.0 MPa, a temperature of 220 °C, a space velocity of 3000 mL / g / h, and an H2 / CO2 volume ratio of 3. The results are summarized in Table 1 below. After 100 hours of continuous catalytic reaction, both the carbon dioxide conversion and methanol selectivity decreased significantly (carbon dioxide conversion decreased by 10%, and methanol selectivity decreased by 15%).
[0110] Comparative Example 2
[0111] In this embodiment, the catalyst was first prepared according to the following steps:
[0112] First, weigh 14.5 g of Cu(NO3)2·3H2O, 5.9 g of Zn(NO3)2·6H2O, and 7.5 g of Al(NO3)3·9H2O, dissolve them in 200 mL of deionized water, and stir at room temperature for 30 min to obtain a homogeneous and transparent aqueous solution. Separately, weigh 3.9 g of 1,4-succinic acid, dissolve it in 20 mL of dimethyl sulfoxide, and add the resulting organic solution to the above aqueous solution. Continue stirring at room temperature for 30 min. Add 31.5 g of citric acid monohydrate to the above materials, then adjust the pH of the materials to 7 using ammonia water, raise the temperature to 90°C, and continue stirring for 6 hours to obtain a gel. Transfer the gel to an oven and dry it at 110°C for 12 hours to obtain a dry gel. Place the obtained dry gel in a muffle furnace and heat it to 450°C at a rate of 1°C / min, calcining it at this temperature for 6 hours. The resulting catalyst is designated as catalyst b.
[0113] Nitrogen adsorption-desorption characterization of catalyst b confirmed that catalyst b has only a mesoporous structure and no microporous structure.
[0114] Using the catalyst prepared in this embodiment, a catalytic reaction for the catalytic hydrogenation of carbon dioxide to methanol was carried out in a fixed-bed reactor at a reaction pressure of 3.0 MPa, a temperature of 220 °C, a space velocity of 3000 mL / g / h, and an H2 / CO2 volume ratio of 3. The results are summarized in Table 1 below. After the catalytic reaction continued for 100 hours, the carbon dioxide conversion rate and methanol selectivity decreased significantly (carbon dioxide conversion rate decreased by 7%, and methanol selectivity decreased by 10%).
[0115] Table 1: Catalytic reaction results of Examples 1-5 and Comparative Examples 1-2
[0116]
[0117] The experimental results above show that the catalysts prepared in the embodiments of the present invention can achieve excellent carbon dioxide conversion and methanol selectivity. However, the methanol selectivity of the catalysts prepared in Comparative Examples 1 and 2 (in Comparative Example 2, the confining structure building agent of Example 1 was replaced with an equimolar amount of succinic acid) without the use of a confining structure building agent in the catalyst preparation process both showed a significant decrease.
Claims
1. A method for preparing a confined catalyst, the method comprising: Step 1: preparing a mixture of a matrix precursor, an active component precursor, an auxiliary component precursor and water; Step 2: adding a confining structure builder to the mixture to form a mixed raw material; Step 3: adding a complexing agent and a pH adjusting agent to the mixed raw material, and then heating at a first temperature to form a gel; Step 4: heat treating the gel to form the confined catalyst.
2. The method of claim 1, wherein, In the Step 1, the matrix precursor is selected from one or more of: a water-soluble salt of aluminum, a water-soluble salt of zirconium, a water-soluble salt or ester of titanium, a water-soluble salt of cerium, a water-soluble salt of niobium, a water-soluble salt of indium; the active component precursor is a water-soluble salt of copper; the auxiliary component precursor is a water-soluble salt of one or more elements selected from: zinc, molybdenum, gold, cobalt, lanthanum, gallium; The molar ratio of the active component precursor to the matrix precursor is 10:1 to 1:5; The molar ratio of the auxiliary component precursor to the matrix precursor is 6:1 to 1:
3.
3. The method of claim 1, wherein, In the Step 2, the confining structure builder is selected from one or more of: benzene, biphenyl, an aromatic hydrocarbon containing two or more fused benzene rings, and can be optionally substituted by one or more substituents selected from: C1-C12 alkyl, hydroxyl, carboxyl, amino, chlorine, bromine, iodine; The molar ratio of the confining structure builder to the matrix precursor is 1:5 to 10:1; In Step 2, the confining structure builder is dissolved in an organic solvent to form an organic solution, and then the organic solution is added to the mixture prepared in Step 1, the organic solvent is selected from one or more of: methanol, ethanol, acetonitrile, acetone, dimethyl sulfoxide, dimethyl formamide, N-methyl pyrrolidone, N-ethyl pyrrolidone, 1-butyl pyrrolidone, dimethyl acetamide, tetrahydrofuran.
4. The method according to claim 1, wherein, In the Step 3, the complexing agent is selected from one or more of: citric acid, oxalic acid, tartaric acid, ethylenediaminetetraacetic acid, aminotriacetic acid, an amino acid, gluconic acid, stearic acid, ethylenediamine; the molar ratio of the matrix precursor to the complexing agent is 2:1 to 1:50; In the Step 3, the pH adjusting agent is selected from one or more of: ammonia, urea, ammonium carbonate, ammonium bicarbonate, urea, formamide, ethylenediamine; the pH of the mixed raw material is adjusted to 5-9 using the pH adjusting agent; In the Step 3, the heating at the first temperature is performed for 1-12 hours at 30-150°C to form a gel.
5. The method of claim 1, wherein, In the Step 4, the drying is performed for 1-24 hours at a second temperature of 50-150°C; The calcination is performed for 1-12 hours at a third temperature of 200-700°C, and the calcination employs a temperature rise rate of 0.1-5°C / min.
6. A confined catalyst, the confined catalyst comprising a matrix, an active component and an auxiliary component, the matrix having a mesoporous structure and comprising oxides of one or more elements selected from: aluminum, zirconium, titanium, cerium, niobium, indium; The active component comprises copper oxide; the promoter comprises an oxide of one or more elements selected from the group consisting of zinc, molybdenum, gold, cobalt, lanthanum, gallium; the confined catalyst further comprises a microporous structure.
7. The constrained catalyst of claim 6, wherein, the confined catalyst comprises 35 to 60 mass% of the matrix, 20 to 60 mass% of the active component, and 1 to 40 mass% of the promoter, based on the total mass of the confined catalyst.
8. The confined catalyst according to claim 6 or 7, which is prepared by the method according to any one of claims 1 to 5.
9. A method for catalyzing a reaction, the method comprising reacting carbon dioxide with hydrogen in the presence of the confined catalyst according to any one of claims 6 to 8 to produce methanol.
10. The catalytic reaction method of claim 9, wherein, The reaction temperature of the catalytic reaction is 180 to 250°C, and the reaction pressure is 1 to 6 MPa.