Metallic monoatomic catalyst, its preparation method and application

Abstract

The application discloses a metal monatomic catalyst and a preparation method and application thereof, and belongs to the technical field of monatomic catalyst preparation.The metal monatomic catalyst is prepared by taking aluminum powder material as a carrier, and through methods such as spin evaporation and chemical transfer reaction, metal monatomic catalysts are formed by uniformly dispersing metal monatomic catalysts on the surface of the aluminum powder.The method is suitable for loading of various metal monatomic catalysts, effectively solves the problems of complexity in the prior art, difficulty in controlling the loading amount of monatomic catalysts and difficulty in large-scale preparation of catalysts, and improves the universality of the monatomic catalyst synthesis method.

Description

Technical Field

[0001] This invention belongs to the field of single-atom catalyst preparation technology, specifically relating to a metal single-atom catalyst, its preparation method, and its application. Background Technology

[0002] Single-atom catalysts are a special type of supported metal catalyst in which all metal components on the support exist in a dispersed single-atom form, without any metal-metal bonds of the same atom. Due to their unique structure, single-atom catalysts exhibit significantly different activities, selectivity, and stability compared to conventional nanocatalysts. Single-atom catalysis has rapidly become a research frontier in the field of catalysis, making it possible to elucidate the structure-activity relationships of catalysts at the atomic and molecular scale.

[0003] Single-atom catalysts exhibit higher catalytic activity compared to nanoparticle and nanocluster catalysts because they achieve nearly 100% atom utilization, thus reducing the amount of supported metal elements such as lead and copper required. Generally, the fabrication methods for single-atom catalysts are complex, with laboratory synthesis yields typically ranging from 0.1 to 10 g per synthesis. Metal loading is usually below 1%, and the types of supported metals are somewhat limited. Furthermore, during the fabrication of single-atom catalysts with higher metal loadings, the aggregation of supported metal atoms into nanoparticles is highly likely, leading to catalyst synthesis failure or affecting the catalytic activity of subsequent reactions.

[0004] Therefore, it is particularly important to develop a general preparation method for single-atom catalysts that is simple to synthesize, has controllable metal types and loading amounts, and can be produced on a large scale. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a metal single-atom catalyst, its preparation method and application, so as to solve the technical problems of complex preparation methods of single-atom catalysts, difficulty in controlling the loading amount, and easy agglomeration to form nanoparticles during the synthesis process.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses for the first time a metal single-atom catalyst, which is formed by uniformly loading a metal single-atom material onto the surface of aluminum powder.

[0008] Preferably, the loading of the metal single-atom material is 0.1% to 5% of the mass of the aluminum powder.

[0009] Preferably, the metal single-atom material includes one or more of Fe, Co, Mn, Cu and Pb.

[0010] Preferably, the aluminum powder is nano-aluminum powder or micron-aluminum powder.

[0011] This invention also discloses a method for preparing the above-mentioned metal single-atom catalyst, comprising the following steps:

[0012] 1) The impregnation method is adopted, with metal salt precursor as solute, which is added to the solvent and ultrasonically mixed. Then, aluminum powder is added as a carrier and stirred thoroughly at room temperature until the metal salt precursor is adsorbed onto the surface of the aluminum powder.

[0013] 2) The solvent was completely removed by rotary evaporation to obtain aluminum powder that adsorbed the metal salt precursor;

[0014] 3) The aluminum powder adsorbed with metal salt precursor is thoroughly ground, and then calcined under sealed conditions in a protective gas atmosphere. After the metal precursor is fully pyrolyzed, a metal single-atom catalyst is obtained.

[0015] Preferably, in step 1), the metal in the metal salt precursor is selected from one or more of Fe(II), Co(II), Cu(II) and Pb(II);

[0016] The mass ratio of the metal to the micron-sized aluminum powder in the metal salt precursor is (0.1~5):100;

[0017] The ultrasonic treatment time is 10~30 min; the stirring time is 8~24 h.

[0018] More preferably, the metal salt precursor in step one is selected from one or more of decacarbonyldimanganese, octacarbonyldicobalt, dodecacarbonyltriferric, acetylacetone iron, acetylacetone cobalt, acetylacetone copper, and acetylacetone lead.

[0019] Preferably, in step 2), during the solvent removal process using rotary evaporation, the water bath temperature of the rotary evaporator is set to 50~70 ℃, the rotation speed is set to 120~140 rpm, and the duration is 30~120 min.

[0020] Preferably, in step 3), the temperature regime for the calcination treatment is as follows: starting from room temperature, the temperature is increased to 100-450 ℃ at a heating rate of 1-5 ℃ / min, and held for 1-3 h.

[0021] The present invention also discloses the effect of the above-mentioned metal single-atom catalyst on improving the thermal properties of materials.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The metal single-atom catalyst disclosed in this invention uses aluminum powder as a carrier and forms a single-atom catalyst by uniformly dispersing metal single atoms on the surface of aluminum powder through methods such as rotary evaporation and chemical transfer reaction.

[0024] Furthermore, the loading amount of the metal single atom can be flexibly adjusted by the amount of metal precursor added, generally ranging from 0.1 wt.% to 5 wt.%. Corresponding to the corresponding metal precursor, the metal single atom may include Fe, Co, Mn, Cu, Pb, etc.

[0025] The method for preparing metal single-atom catalysts disclosed in this invention is simple, relatively low in cost, and allows for flexible adjustment of catalyst yield and single-atom loading. Depending on the capacity of the quartz tube, different masses (0.1~100g) of aluminum powder support and metal salt precursor mixture can be loaded, ultimately achieving large-scale synthesis of aluminum-based single-atom catalysts. Furthermore, the method of this invention is applicable to the loading of various metal single atoms, effectively solving the shortcomings of existing technologies such as complex synthesis, difficulty in controlling single-atom loading, and difficulty in large-scale catalyst preparation, thus improving the universality of single-atom catalyst synthesis methods. Attached Figure Description

[0026] Figure 1 These are X-ray diffraction (XRD) patterns of the original micron-sized aluminum powder and the metal single-atom catalysts prepared in Examples 1-4 of this invention;

[0027] Figure 2 This is an aberration-corrected scanning transmission electron microscope (AC) image of the Fe single-atom catalyst prepared in Example 1. STEM images;

[0028] Figure 3 The aberration-corrected scanning transmission electron microscope (AC) of the Co single-atom catalyst prepared in Example 2 is used to analyze the catalyst. STEM images;

[0029] Figure 4 This is an aberration-corrected scanning transmission electron microscope (AC) image of the Cu single-atom catalyst prepared in Example 3. STEM images;

[0030] Figure 5 This is an aberration-corrected scanning transmission electron microscope (AC) image of the Pb single-atom catalyst prepared in Example 4. STEM images;

[0031] Figure 6 This is a synchrotron radiation diagram of the Co single-atom catalyst prepared in Example 2;

[0032] Figure 7 This is a synchrotron radiation diagram of the Cu single-atom catalyst prepared in Example 3;

[0033] Figure 8 This is a synchrotron radiation diagram of the Pb single-atom catalyst prepared in Example 4;

[0034] Figure 9 These are simultaneous thermal analysis (TG-DSC) diagrams of the original micron-sized aluminum powder and the metal single-atom catalysts prepared in Examples 1-4 of this invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] The present invention will now be described in further detail with reference to the accompanying drawings:

[0038] Example 1

[0039] This embodiment provides a single-atom catalyst with micron-sized aluminum powder as a carrier and a theoretical Fe loading of 0.2%, which is prepared by the following steps:

[0040] 0.00596 g of dodecacarbonyltriferrite was weighed and placed in a 150 mL eggplant-shaped flask, and 50 mL of anhydrous ethanol was added. After ultrasonic dispersion for 30 min, a homogeneous solution was obtained. 1 g of micron-sized aluminum powder was weighed and placed in the solution, ultrasonically dispersed for 30 min, and then stirred at 25 ℃ for 24 h. The solvent was removed by rotary evaporation to obtain a gray solid, which was dried at 60 ℃ for 10 h and then thoroughly ground. The powder was transferred to a quartz tube and sealed. The sealed quartz tube was placed in a tube furnace, and the temperature was increased to 150 ℃ at a rate of 5 ℃ / min under a protective gas atmosphere and maintained at 150 ℃ for 1 h. After cooling, the product was washed and filtered to obtain the gray target product, i.e., the iron single-atom catalyst.

[0041] Figure 1 The diagram schematically illustrates the X-ray diffraction (XRD) patterns of Example 1 of the present invention and micron-sized aluminum powder. For example... Figure 1 As shown, in Figure 1 In the XRD results of Example 1, there are only diffraction peaks belonging to the micron-sized aluminum powder carrier, and no related diffraction peaks of Fe nanoparticles and their oxides. This indirectly indicates that the loaded Fe has a high degree of dispersion. Figure 2 This is an image from an aberration-corrected scanning transmission electron microscope (AC-STEM) of Embodiment 1 of the present invention. Figure 2 As shown, AC-STEM confirmed that Fe exists in a single-atom form on the surface of the micron-sized aluminum powder support. The Fe content in the Fe single-atom catalyst prepared in Example 1 was determined by ICP-AES. The AES results show that the actual Fe loading is 0.19%.

[0042] The thermal properties of the Fe single-atom catalyst prepared in Example 1 and the unsupported micron-sized aluminum powder support were tested. The TG-DSC results are as follows: Figure 9 As shown. Figure 9 As shown in (a), the weight of unmodified micron-sized aluminum powder increased to 156.3%, the exothermic peak temperature of the reaction was 1072.61 °C, and the released heat was 136.81 mJ / mg. Figure 9 As shown in Figure (b), the weight of the Fe single-atom catalyst prepared in Example 1 increased to 168.8%, and the exothermic peak temperature of the reaction was advanced to 998.29 °C, with an exothermic heat release of 170.12 mJ / mg. The exothermic heat release of the Fe single-atom catalyst prepared in Example 1 was 24.35% higher than that of the unmodified micron-sized aluminum powder.

[0043] Example 2

[0044] This embodiment provides a single-atom catalyst with micron-sized aluminum powder as a support and a theoretical Co loading of 0.2%, which is prepared by the following steps:

[0045] 0.0058 g of cobalt octacarbonyl was weighed and placed in a 150 mL round-bottom flask, and 50 mL of anhydrous ethanol was added. After ultrasonic dispersion for 30 min, a homogeneous solution was obtained. 1 g of micron-sized aluminum powder was weighed and placed in the solution, ultrasonically dispersed for 30 min, and then stirred at 25 °C for 24 h. The solvent was removed by rotary evaporation to obtain a gray solid, which was dried at 60 °C for 10 h and then thoroughly ground. The powder was transferred to a quartz tube and sealed. The sealed quartz tube was placed in a tube furnace, and the temperature was increased to 180 °C at a rate of 5 °C / min under a protective gas atmosphere and maintained at 180 °C for 1 h. After cooling, the product was washed and filtered to obtain the gray target product, i.e., the cobalt single-atom catalyst.

[0046] Figure 1 The diagram schematically illustrates the X-ray diffraction (XRD) patterns of Example 2 of the present invention and micron-sized aluminum powder. For example... Figure 1 As shown, in Figure 1 In the XRD results of Example 2, there are only diffraction peaks belonging to the micron-sized aluminum powder carrier, and no related diffraction peaks of Co nanoparticles and their oxides. This indirectly indicates that the loaded Co has a high degree of dispersion. Figure 3 This is an image from an aberration-corrected scanning transmission electron microscope (AC-STEM) of Embodiment 2 of the present invention. Figure 3 As shown, AC-STEM confirmed that Co exists in a single-atom form on the surface of a micron-sized aluminum powder carrier. Figure 6 As shown, based on synchrotron radiation data, no Co-Co bonds were found in the Co / Al catalyst, proving that Co mainly exists in single-atom form. The Co content in the Co single-atom metal catalyst prepared in Example 2 was determined by ICP-AES. The AES results show that the actual load on Co is 0.19%.

[0047] The thermal performance of the Co single-atom catalyst prepared in Example 2 was tested, and the TG-DSC results are as follows: Figure 9 As shown in (c), the weight of the Co single-atom catalyst prepared in Example 2 increased by 158%, and the exothermic peak temperature of the reaction was advanced to 1031.18 °C, with an exothermic heat release of 158.03 mJ / mg. The exothermic heat release of the Co single-atom catalyst prepared in Example 2 was 15.51% higher than that of the unmodified micron-sized aluminum powder.

[0048] Example 3

[0049] This embodiment provides a single-atom catalyst with micron-sized aluminum powder as a support and a theoretical Cu loading of 0.2%, which is prepared by the following steps:

[0050] 0.0082 g of copper acetylacetonate was weighed and placed in a 150 mL round-bottom flask, and 50 mL of anhydrous ethanol was added. After ultrasonic dispersion for 30 min, a homogeneous solution was obtained. 1 g of micron-sized aluminum powder was weighed and placed in the solution, ultrasonically dispersed for 30 min, and then stirred at 25 °C for 24 h. The solvent was removed by rotary evaporation to obtain a gray solid, which was dried at 60 °C for 10 h and then thoroughly ground. The powder was transferred to a quartz tube and sealed. The sealed quartz tube was then placed in a tube furnace, and the temperature was increased to 150 °C at a rate of 5 °C / min under a protective gas atmosphere and maintained at 150 °C for 1 h. After cooling, the product was washed and filtered to obtain the gray target product, i.e., the copper single-atom catalyst.

[0051] Figure 1 The diagram schematically illustrates the X-ray diffraction (XRD) patterns of Example 3 of the present invention and micron-sized aluminum powder. For example... Figure 1 As shown, in Figure 1 In the XRD detection results of Example 3, only the diffraction peaks of the micron-sized aluminum powder carrier were found, and no related diffraction peaks of Cu nanoparticles and their oxides were found. This indirectly indicates that the loaded Cu has a high degree of dispersion. Figure 4 This is an image obtained using an aberration-corrected scanning transmission electron microscope (AC-STEM) according to Embodiment 3 of the present invention. Figure 4 As shown, AC-STEM confirmed that Cu exists in a single-atom form on the surface of a micron-sized aluminum powder carrier. Figure 7 As shown, based on synchrotron radiation data, no Cu-Cu bonds were found in the Cu / Al catalyst, proving that Cu mainly exists in single-atom form. The Cu content in the Cu single-atom catalyst prepared in Example 3 was determined by ICP-AES. The AES results show that the actual Cu loading is 0.18%.

[0052] The thermal performance of the Cu single-atom catalyst prepared in Example 3 was tested, and the TG-DSC results are as follows: Figure 9 As shown in Figure (d), the weight of the Cu single-atom catalyst prepared in Example 3 increased to 163.5%, and the exothermic peak temperature of the reaction was advanced to 1049.46 °C, with an exothermic heat release of 144.38 mJ / mg. The exothermic heat release of the Cu single-atom catalyst prepared in Example 3 was 5.53% higher than that of the unmodified micron-sized aluminum powder.

[0053] Example 4

[0054] This embodiment provides a single-atom catalyst with micron-sized aluminum powder as a support and a theoretical Pb loading of 0.2%, which is prepared by the following steps:

[0055] 0.0039 g of lead acetylacetone was weighed and placed in a 150 mL round-bottom flask, and 50 mL of anhydrous ethanol was added. After ultrasonic dispersion for 30 min, a homogeneous solution was obtained. 1 g of micron-sized aluminum powder was weighed and placed in the solution, ultrasonically dispersed for 30 min, and then stirred at 25 °C for 12 h. The solvent was removed by rotary evaporation to obtain a gray solid, which was dried at 60 °C for 10 h and then thoroughly ground. The powder was transferred to a quartz tube and sealed. The sealed quartz tube was then placed in a tube furnace, and the temperature was increased to 450 °C at a rate of 5 °C / min under a protective gas atmosphere and maintained at 450 °C for 1 h. After cooling, the product was washed and filtered to obtain the gray target product, i.e., the lead single-atom catalyst.

[0056] Figure 1 The diagram schematically illustrates the X-ray diffraction (XRD) patterns of Example 4 of the present invention and micron-sized aluminum powder. For example... Figure 1 As shown, in Figure 1 In the XRD results of Example 4, only the diffraction peaks of the micron-sized aluminum powder carrier were found, and no diffraction peaks related to Pb nanoparticles and their oxides were found. This indirectly indicates that the loaded Pb has a high degree of dispersion. Figure 5 This is an image from an aberration-corrected scanning transmission electron microscope (AC-STEM) of Embodiment 4 of the present invention. Figure 5 As shown, AC-STEM confirmed that Pb exists in a single-atom form on the surface of a micron-sized aluminum powder carrier. Figure 8 As shown, based on synchrotron radiation data, no obvious Pb-Pb bonds appeared in the Pb / Al catalyst, proving that Pb mainly exists in single-atom form. The Pb content in the Pb single-atom catalyst prepared in Example 4 was determined by ICP-AES. The AES results show that the actual load on Pb is 0.21%.

[0057] The thermal performance of the Pb single-atom catalyst prepared in Example 4 was tested, and the TG-DSC results are as follows: Figure 9 As shown in (e), the weight of the Pb single-atom catalyst prepared in Example 4 increased to 160.7%, and the exothermic peak temperature of the reaction was advanced to 1006.82 °C, with an exothermic heat release of 148.54 mJ / mg. The exothermic heat release of the Pb single-atom catalyst prepared in Example 4 was 8.57% higher than that of the unmodified micron-sized aluminum powder.

[0058] The micron-sized aluminum powder carriers with different types of metal atoms that were synthesized in Examples 1-4 further demonstrate the universality of the preparation method of the present invention. Any obvious variations or modifications derived therefrom are still within the protection scope of the preparation method of the present invention.

[0059] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. The application of a metal single-atom catalyst in improving the thermal properties of materials, characterized in that, This metal single-atom catalyst is formed by uniformly loading metal single-atom material onto the surface of micron-sized aluminum powder; The single-atom metallic material includes one or more of Fe, Co, Cu, and Pb; This metal single-atom catalyst was prepared by the following method: 1) The impregnation method is adopted, with metal salt precursor as solute, which is added to the solvent and ultrasonically mixed. Then, micron-sized aluminum powder is added as a carrier and stirred thoroughly at room temperature until the metal salt precursor is adsorbed onto the surface of micron-sized aluminum powder. 2) The solvent was completely removed by rotary evaporation to obtain micron-sized aluminum powder that adsorbed the metal salt precursor; 3) The micron-sized aluminum powder adsorbed with metal salt precursor is thoroughly ground, and then calcined under sealed conditions in a protective gas atmosphere. After the metal precursor is fully pyrolyzed, a metal single-atom catalyst is obtained.

2. The application according to claim 1, characterized in that, The loading of the metal single-atom material is 0.1%-0.2% of the mass of the micron-sized aluminum powder.

3. The application according to claim 1, characterized in that, In step 1), the metal in the metal salt precursor is selected from one or more of Fe(II), Co(II), Cu(II) and Pb(II); The mass ratio of the metal to the micron-sized aluminum powder in the metal salt precursor is (0.1-5):100; The ultrasonic treatment time is 10-30 min; the stirring time is 8-24 h.

4. The application according to claim 1, characterized in that, Step 1) The metal salt precursor is selected from one or more of the following: cobalt octacarbonyl, iron dodecyltricarbonyl, iron acetylacetonate, cobalt acetylacetonate, copper acetylacetonate, and lead acetylacetonate.

5. The application according to claim 1, characterized in that, In step 2), during the solvent removal process using rotary evaporation, the water bath temperature of the rotary evaporator is set to 50-70 ℃, the rotation speed is set to 120-140 rpm, and the duration is 30-120 min.

6. The application according to claim 1, characterized in that, In step 3), the calcination conditions are set as follows: starting from room temperature, the temperature is increased to 100-450 ℃ at a heating rate of 1-5 ℃ / min, and held for 1-3 h.

Images