A method for preparing a composite metal catalyst
By employing a migration heat treatment method for host and guest solid materials, the problem of uneven metal dispersion in composite metal catalysts was solved, achieving uniform synthesis and thermal stability of active sites and simplifying the preparation process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TSINGHUA UNIVERSITY
- Filing Date
- 2023-11-08
- Publication Date
- 2026-06-12
AI Technical Summary
Existing methods for preparing composite metal catalysts cannot achieve uniform dispersion of the metals in the catalyst, making it difficult to synthesize uniform active sites. Furthermore, traditional methods are complex, costly, and have poor thermal stability.
By simply mixing and heat-treating the host and guest solid materials, a migrating metal is made into the host solid material under a reducing atmosphere using a reducing gas, forming a composite metal catalyst with the host metal. The catalyst is prepared using reactors such as fluidized beds and stirred beds.
The homogeneous synthesis of catalyst active sites was achieved. The steps were simple, the conditions were mild, and the preparation was easy to scale up. The catalyst active sites also exhibited good thermal stability.
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Figure CN117504945B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to heterogeneous catalysts, and more particularly to a composite metal heterogeneous catalyst containing multiple metals. Background Technology
[0002] Composite metal catalysts are widely used as heterogeneous catalysts in chemical reaction processes. Their active sites are composed of multiple metal elements, and the electronic properties and geometry of these active sites are more suitable for catalytic reactions than those of single metals. Composite metal catalysts exhibit unique catalytic performance in many reactions, such as catalytic hydrogenation, steam reforming, and dehydrogenation.
[0003] Traditional composite metal catalysts generally employ co-impregnation or co-precipitation methods, where multiple desired metal precursors are mixed and dissolved in a liquid solvent. The mixed solution is then dropwise added to the surface of a solid support or a precipitant is used to form a solid phase, followed by drying. CN1006202B discloses a method for preparing supported hydroconversion catalysts, using an impregnation method to impregnate metal precursors onto supports such as silica via an aqueous solution. CN101733106A discloses a method for preparing supported nickel catalysts, using a precipitant to precipitate metal elements in the precursor solution into a solid phase to obtain the catalyst. While co-impregnation or co-precipitation methods are relatively simple and easy to scale up, they cannot achieve uniform dispersion of the metals in the catalyst. The metal elemental composition of the supported nanoparticles varies greatly, making it difficult to synthesize catalysts with uniform active sites. Atomic layer deposition (ALD) technology utilizes pulsed gaseous metal precursors to controllably form active sites through surface reactions. CN114849790A discloses a supported metal catalyst and its preparation method, which forms a supported non-noble metal oxide through atomic layer deposition on the surface of a support. CN111790376A discloses a sub-nanometer metal catalyst and its preparation method, which also utilizes atomic layer deposition to obtain sub-nanometer metals existing in an atomically dispersed form. Although atomic layer deposition can achieve uniform and controllable synthesis of active sites, it generally requires a vacuum environment and an organometallic pre-process, and faces problems such as replication of synthesis steps, stringent synthesis conditions, high cost, and poor thermal stability of the catalyst.
[0004] In summary, developing a simple method for preparing composite metal catalysts that achieves uniform synthesis of active sites is of great significance. Summary of the Invention
[0005] The purpose of this invention is to provide a method for the controllable preparation of heterogeneous composite metal catalysts containing multiple metals. This method achieves the transfer of migrating metals from the guest solid material to the host solid material through simple mixing and migration heat treatment of the host and guest solid materials, further forming a composite metal catalyst with the host metal in the host solid material. This method has advantages such as simple steps, mild synthesis conditions, and ease of scale-up preparation, while also enabling the controllable synthesis of composite metal catalysts with uniform active sites.
[0006] To achieve the above objectives, this invention provides a method for preparing a composite metal catalyst, characterized in that a guest solid material and a host solid material are physically mixed, and then subjected to migration heat treatment in a reducing gas atmosphere; wherein the guest solid material includes a migrating metal, the host solid material includes a host metal, and the valence state of the migrating metal is one or a combination of metallic and oxidized states. During the migration heat treatment, the migrating metal migrates into the host solid material via the gas phase under the action of the reducing gas, forming a composite metal catalyst with the host metal.
[0007] Further, the reducing gas contains a reducing component, which is one or a combination of H2, NH3, and CO, and the pressure of the reducing gas is not less than one atmosphere (P ≥ 1 atm). When the reducing component contains H2, the migrating metal is one or a combination of Cu, Zn, Cd, Sb, Li, and Ga; when the reducing component contains one or a combination of CO or NH3, the migrating metal is one or a combination of Group VIII or Group IB transition metals. During the migration heat treatment, the reducing component interacts with the migrating metal, causing the migrating metal to form one or a combination of metal atoms, carbonyl metal complexes, or amino metal complexes, and then migrate into the host metal material.
[0008] Furthermore, the temperature of the migration heat treatment is 300℃~1000℃, preferably 350℃~600℃, and even more preferably 350℃~450℃. The temperature required for the migration heat treatment is achieved by direct heating or indirect heating.
[0009] Furthermore, the host solid material also includes a support, on which the host metal is loaded. The host metal is dispersed in one or a combination of single-atom, diatomic, or nanoparticle forms. Specifically, when the host metal is dispersed in a single-atom form, the composite metal catalyst comprises diatomic particles composed of a migrating metal and the host metal; and / or, when the host metal is dispersed in a diatomic form, the composite metal catalyst comprises n atoms composed of a migrating metal and the host metal, where n ≥ 3; and / or, when the host metal is dispersed in nanoparticle forms, the composite metal catalyst comprises new nanoparticles composed of a migrating metal and the host metal, wherein the new nanoparticles are one or a combination of intermetallic compounds, metal solid solutions, and disordered metal alloys.
[0010] Furthermore, it is characterized by utilizing a reactor to realize the preparation process of the composite metal catalyst, wherein the reactor is one or a combination of a fluidized bed, a stirred bed, and a fixed bed, and the preparation process includes the following steps: S1 loading the guest solid material and the host solid material into the reactor, and introducing a reducing gas into the reactor; S2 subjecting the guest and host solid materials to heat treatment; S3 separating the host solid material after heat treatment to obtain the composite metal catalyst.
[0011] Furthermore, the guest solid material is one or a combination of metal oxide, elemental metal, supported metal, or supported metal oxide; the support in the host solid material is one or a combination of metal oxide, carbon support, and molecular sieve.
[0012] Further, according to a preferred embodiment of the present invention, the guest solid material includes ZnO, the migrating metal is Zn, the reducing component of the reducing gas is H2, during the migration heat treatment, the Zn element in ZnO migrates to the host solid material in the Zn atomic state, the host metal of the host solid material includes one or a combination of transition metals, the dispersion form of the host metal is nanoparticles, and the formed composite metal catalyst includes intermetallic compound nanoparticles composed of the migrating metal Zn and the host metal, wherein the elemental ratio of the migrating metal to the host metal in the intermetallic compound nanoparticles is 0.5 to 1.5.
[0013] Furthermore, its characteristic lies in that the guest solid material and the host solid material have different particle sizes, and after migration heat treatment, the guest solid material and the host solid material are separated by particle sieving.
[0014] The beneficial effects of this invention are that it prepares composite metal catalysts by simple mixing and migration heat treatment of host and guest solid phase materials. Compared with the ALD method, this method has the advantages of simple steps, mild synthesis conditions, and easy scale-up preparation.
[0015] The beneficial effect of this invention is that it enables the transfer of migrating metals from the guest solid material to the host solid material, and further forms a composite metal catalyst with the host metal in the host solid material. Compared with the traditional impregnation method catalyst, this method can controllably synthesize composite metal catalysts with uniform active sites.
[0016] The beneficial effects of this invention also lie in the fact that by using migration heat treatment to synthesize composite metal catalysts, the sintering of catalyst active sites can be suppressed, while the catalyst active sites also have good thermal stability. Attached Figure Description
[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:
[0018] Figure 1 This is the CO-FTIR characterization diagram of the sample catalyst.
[0019] (i) Sample-0; (ii) Sample-0.5; (iii) Sample-1; (iv) Sample-2; (v) Sample-4; (vi) Sample-10;
[0020] Figure 2 This is the HAADF-STEM characterization image of the sample catalyst. Detailed Implementation
[0021] The following describes in detail, with reference to the accompanying drawings, several preferred embodiments of the present invention for the preparation of composite metal catalysts.
[0022] Before describing the embodiments in detail, some terms used herein will be explained.
[0023] Migration heat treatment: refers to the process by which metals in the guest solid phase material migrate to the host solid phase material and react with the host metal in the host solid phase material to form a composite metal oxide.
[0024] Migration temperature: refers to the temperature at which the host solid material and the guest solid material need to be heated during the migration heat treatment process.
[0025] Migrating metal: In the migration heat treatment described herein, the metal element contained therein migrates into the host solid material and forms a composite metal catalyst with the host metal. The migrating metal can exist in one or a combination of the metal state or the metal oxidation state.
[0026] Host metal: In the migration heat treatment described in this paper, it accepts the migrating metal to form a composite metal catalyst. The host metal can exist in one or a combination of the metallic state or the metal oxidation state.
[0027] Seven embodiments will be described below, specifically:
[0028] Example 1 synthesizes RhZn intermetallic compound catalyst using the method provided by this invention. Comparative Example 1 is a bimetallic catalyst prepared by the conventional impregnation method. The results of Example 1 and Comparative Example 1 show that the preparation method provided by this invention has successfully synthesized a bimetallic intermetallic compound catalyst with uniform metal dispersion and uniform metal element composition of nanoparticles, achieving the synthesis of catalyst with uniform active sites.
[0029] Example 2 uses the method provided by the present invention to synthesize a bimetallic compound catalyst in which the host metal is one of the transition metals of group VIII or group IB, the migrating metal is Zn, and the active sites are uniform.
[0030] Examples 3-4 use the method provided by this invention to synthesize one or a combination of intermetallic compounds, metal solid solutions, and disordered metal alloys.
[0031] Example 5 uses the method provided by the present invention to synthesize a structurally uniform diatomic or multiatomic catalyst.
[0032] Example 6 uses the method provided by the present invention to synthesize a composite metal catalyst with uniform structure containing metal-metal oxide interface sites.
[0033] Example 7 is an example of a process flow for the large-scale preparation of composite metal catalysts provided by the present invention, which utilizes one or a combination of fluidized bed and solid stirred bed to achieve the large-scale preparation of catalysts.
[0034] Example 1
[0035] Sample catalyst was prepared using the following steps.
[0036] (1) The guest solid material and the host solid material are mechanically and physically mixed and then loaded into a fixed bed reduction tube. The guest solid material contains ZnO, the host solid material contains the host metal Rh, and the host solid material also includes a carrier. The carrier in the host solid material is one or a combination of metal oxide, carbon carrier, and molecular sieve. The host metal is loaded on the carrier and the dispersion form of the host metal is nanoparticles.
[0037] (2) A reducing gas is introduced into the reduction tube. The reducing gas contains a reducing component, which is H2. The absolute pressure of the reducing gas is not less than that of a large gas (P≥1 atm). The reduction tube is raised to the migration temperature T and maintained for the required migration heat treatment time t. The migration temperature T is 300℃-600℃, preferably 350-450℃, and the migration heat treatment time t is 0.5-10h. During the migration heat treatment, the Zn element in ZnO migrates to the host solid material in the Zn atomic state. The resulting composite metal catalyst contains RhZn intermetallic compound nanoparticles composed of the migrating metal Zn and the host metal Rh.
[0038] (3) The composite metal catalyst was obtained, and the catalysts with different migration heat treatment times t were numbered "sample-t", and the catalysts were characterized by CO-FTIR. Figure 1 As shown, with the increase of migration heat treatment time t, the linear adsorption of CO on the Rh metal surface gradually decreases from 20-60 cm⁻¹. -1 Offset to 2030cm -1 The larger the t value, the more structurally complete RhZn intermetallic compounds are formed in the catalyst. Zn electrons in the RhZn intermetallic compounds transfer to the Rh metal surface, resulting in stronger adsorption of CO by Rh. Therefore, the linear adsorption peak of CO shifts to lower wavenumbers. With increasing t, the peak intensities of Rh(CO)2 and Rh2(CO)3 species continuously decrease, and the CO bridging adsorption intensity on the Rh surface also decreases. At t values of 4 h and 10 h, the CO bridging adsorption peak is essentially undetectable.
[0039] Comparative Example 1
[0040] A comparative catalyst was prepared using a traditional co-impregnation method. The required Zn and Rh metal salt precursors were mixed and dissolved in an aqueous phase, with a Zn / Rh molar ratio of 1:1. The mixed metal solution was then dropped onto the surface of a solid support, which was one or a combination of metal oxides, carbon supports, and molecular sieves. Finally, the catalyst was dried, calcined, and reduced to obtain the comparative catalyst, designated "Comparative-IMP".
[0041] Different catalysts were characterized using EDS, and the elemental proportions of nanoparticles in the catalysts were analyzed and summarized in Table 1. In the table, NP represents six different nanoparticles randomly selected from the catalysts. With increasing time t, the fluctuations in the metal ratios among different particles in the sample catalyst decreased, indicating that increasing the migration heat treatment time t is beneficial for forming intermetallic compound catalysts with a uniform Zn / Rh ratio. In contrast, catalysts prepared by the traditional co-impregnation method exhibited significant differences in Zn / Rh ratios among different particles, resulting in highly heterogeneous microscopic active sites.
[0042] Table 1. Molar ratio of Zn / Rh in nanoparticles of the catalyst
[0043]
[0044] Further evaluation of the selective hydrogenation reaction of acetylene using different catalysts was conducted at reaction temperatures of 150℃-200℃, space velocities of 10000-60000 mL / g / h, acetylene concentration in the feed gas of 1%-10%, and H2 / C2H2 ratio of 4-20. The reaction results are shown in Table 2.
[0045] Table 2 Evaluation of Acetylene Hydrogenation Reaction
[0046]
[0047] As can be seen from the table, the reaction performance of the catalyst can be improved by increasing the migration heat treatment time to more than 4 hours using the preparation method provided by this invention. Compared with the catalyst prepared by the traditional impregnation method, the sample catalyst synthesized by the preparation method provided by this invention can significantly improve the conversion rate and the selectivity of the target product ethylene by increasing the migration heat treatment time.
[0048] The results of Example 1 and Comparative Example 1 demonstrate that the preparation method provided by this invention patent has significant advantages over the traditional co-impregnation method. By increasing the migration heat treatment time, a bimetallic intermetallic compound catalyst with uniformly dispersed metals and a uniform metal elemental composition in the nanoparticles was synthesized, achieving the synthesis of catalysts with uniform active sites. Further evaluation of the acetylene hydrogenation reaction shows that increasing the migration heat treatment time can significantly improve the activity and selectivity of the catalyst.
[0049] Example 2
[0050] Sample catalyst was prepared using the following steps.
[0051] (1) The guest solid material and the host solid material are mechanically and physically mixed and then loaded into a fixed bed reduction tube. The guest solid material contains ZnO, and the host solid material contains a host metal. The host metal is one or a combination of transition metals from group VIII or group IB. The host solid material also includes a support. The support in the host solid material is one or a combination of metal oxide, carbon support, and molecular sieve. The host metal is loaded on the support and the dispersion form of the host metal is nanoparticles.
[0052] (2) A reducing gas is introduced into the reduction tube, the reducing gas containing a reducing component, the reducing component being H2; the reduction tube is raised to the migration temperature T and maintained for the required migration heat treatment time t, the migration temperature T being 300-700℃, preferably 350-470℃, the migration heat treatment time t being 0.5-10h; during the migration heat treatment, the Zn element in ZnO migrates to the host solid material in the Zn atomic state, and the resulting composite metal catalyst contains intermetallic compound nanoparticles composed of the migrating metal Zn and the host metal.
[0053] (3) The composite metal catalyst was obtained, and the catalysts containing different host metals were numbered "sample-M".
[0054] Typical catalysts were characterized using HAADF-STEM, such as... Figure 2 As shown, the crystal structure of the nanoparticles in the sample-Rh, sample-Pd, and sample-Pt catalysts is typical of intermetallic compound catalysts.
[0055] Figure 2 HAADF-STEM characterization showed that Example 2 successfully synthesized a bimetallic compound catalyst with a host metal of Group VIII or IB, a migrating metal of Zn, and uniform active sites using the method of the present invention.
[0056] Example 3
[0057] Composite metal catalysts were prepared using the following steps.
[0058] (1) The guest solid material and the host solid material are mechanically and physically mixed and then loaded into a fixed bed reduction tube. The guest solid material contains a migrating metal, which is one or a combination of Cu, Cd, Sb, Li, and Ga. The host solid material contains a host metal, which is one or a combination of transition metals from Group VIII or Group IB. The host solid material also includes a support, which is one or a combination of metal oxide, carbon support, and molecular sieve. The host metal is loaded on the support and the dispersion form of the host metal is nanoparticles.
[0059] (2) A reducing gas containing a reducing component is introduced into a reduction tube. The reducing component is one or a combination of H2, NH3, and CO. The reduction tube is then raised to a migration temperature T and maintained for a required migration heat treatment time t. The migration temperature T is 300-900℃, preferably 400-600℃, and the migration heat treatment time t is 0.5-10h. During the migration heat treatment, the guest solid material containing the migrating metal migrates into the host solid material. The resulting composite metal catalyst contains new nanoparticles composed of the migrating metal and the host metal. The new nanoparticles are one or a combination of intermetallic compounds, metal solid solutions, and disordered metal alloys.
[0060] Characterization techniques such as XRD and HAADF-STEM confirmed that Example 3 successfully synthesized one or a combination of intermetallic compounds, metal solid solutions, and disordered metal alloys.
[0061] Example 4
[0062] Composite metal catalysts were prepared using the following steps.
[0063] (1) The guest solid material and the host solid material are mechanically and physically mixed and then loaded into a fixed bed reduction tube. The guest solid material contains a migrating metal, which is one or a combination of transition metals of group VIII or group IB. The host solid material contains a host metal, which is one or a combination of transition metals of group VIII or group IB. The host solid material also includes a support, which is one or a combination of metal oxide, carbon support, and molecular sieve. The host metal is loaded on the support and the dispersion form of the host metal is nanoparticles.
[0064] (2) A reducing gas is introduced into the reduction tube, the reducing gas containing a reducing component, which is one or a combination of H2, NH3 and CO; the reduction tube is raised to the migration temperature T and maintained for the required migration heat treatment time t, the migration temperature T being 300-900℃, preferably 400-600℃, and the migration heat treatment time t being 0.5-10h; during the migration heat treatment, the guest solid material containing the migrating metal migrates into the host solid material, and the formed composite metal catalyst contains new nanoparticles composed of the migrating metal and the host metal, the new nanoparticles being one or a combination of intermetallic compounds, metal solid solutions, and disordered metal alloys.
[0065] Characterization techniques such as XRD and HAADF-STEM confirmed that Example 4 successfully synthesized one or a combination of intermetallic compounds, metal solid solutions, and disordered metal alloys.
[0066] Example 5
[0067] Composite metal catalysts were prepared using the following steps.
[0068] (1) The guest solid material and the host solid material are mechanically and physically mixed and then loaded into a fixed bed reduction tube. The guest solid material contains a migrating metal, which is one or a combination of transition metals in the periodic table. The host solid material contains a host metal, which is one or a combination of transition metals in the periodic table. The host solid material also includes a support, which is one or a combination of metal oxide, carbon support, and molecular sieve. The host metal is loaded on the support and the dispersion form of the host metal is monatomic or diatomic.
[0069] (2) A reducing gas is introduced into the reduction tube, the reducing gas containing a reducing component, which is one or a combination of H2, NH3 and CO; the reduction tube is raised to the migration temperature T and maintained for the required migration heat treatment time t, the migration temperature T being 300-900℃, preferably 400-600℃, and the migration heat treatment time t being 0.5-10h; during the migration heat treatment, the guest solid material containing the migrating metal migrates into the host solid material, forming diatomic or polyatomic forms with the monatomic host metal in the host solid material.
[0070] Characterization techniques such as XRD and HAADF-STEM confirmed that Example 5 successfully synthesized a structurally uniform diatomic or multiatomic catalyst.
[0071] Example 6
[0072] Composite metal catalysts were prepared using the following steps.
[0073] (1) The guest solid material and the host solid material are mechanically and physically mixed and then loaded into a fixed-bed reduction tube. The guest solid material contains a migrating metal, which is one or a combination of transition metals in the periodic table; the host solid material contains a host metal, which is one or a combination of transition metals in the periodic table, and the host metal is a metal oxide. The host solid material also includes a support, which is one or a combination of metal oxide, carbon support, and molecular sieve.
[0074] (2) A reducing gas is introduced into the reduction tube, the reducing gas containing a reducing component, which is one or a combination of H2, NH3 and CO; the reduction tube is raised to the migration temperature T and maintained for the required migration heat treatment time t, the migration temperature T being 300-900℃, preferably 400-600℃, and the migration heat treatment time t being 0.5-10h; during the migration heat treatment, the migrating metal contained in the guest solid material migrates into the host solid material and forms metal-metal oxide interface sites with the host metal oxide in the host solid material.
[0075] Characterization techniques such as XRD and HAADF-STEM confirmed that Example 6 successfully synthesized a composite metal catalyst with a uniform structure containing metal-metal oxide interface sites.
[0076] Example 7
[0077] The following steps were used to achieve the scale-up preparation of composite metal catalysts.
[0078] (1) The guest solid material and the host solid material are mechanically and physically mixed and then loaded into a reactor. The guest solid material contains a migrating metal, and the host solid material contains a host metal; the host solid material also includes a carrier, and the carrier in the host solid material is one or a combination of metal oxide, carbon carrier, and molecular sieve, and the host metal is loaded on the carrier; the reactor is one or a combination of fluidized bed and solid stirred bed.
[0079] (2) A reducing gas is introduced into the reactor to raise the reduction tube to the migration temperature T and maintain it for the required migration heat treatment time t. The migration temperature T is 300-900℃ and the migration heat treatment time t is 0.5-10h. The guest solid material and the host solid material are uniformly physically mixed in the reactor by gas fluidization or mechanical stirring. The pressure in the reactor is not less than one atmosphere (P≥1atm).
[0080] (3) The guest solid material and the host solid material have different particle sizes. After migration heat treatment, the guest solid material and the host solid material are separated by particle sieving to obtain a composite metal catalyst.
[0081] Example 7 successfully achieved the scale-up preparation of composite metal catalysts using one or a combination of fluidized bed and solid stirred bed.
[0082] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0083] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A method for preparing a composite metal catalyst, characterized in that, After physically mixing the guest solid material and the host solid material, a migration heat treatment is performed in a reducing gas atmosphere. The guest solid material includes a migrating metal, and the host solid material includes a host metal; During the migration heat treatment process, the migrating metal migrates from the gas phase to the host solid material under the action of reducing gas, forming a composite metal catalyst with the host metal. The guest solid material is one or a combination of metal oxide, elemental metal, supported metal, or supported metal oxide. The temperature of the migration heat treatment is 350 ℃ ~ 1000 ℃; The migrating metal is one or a combination of Zn, Cd, Sb, Li, and Ga; the host metal is one or a combination of transition metals from Group VIII or Group IB.
2. The preparation method according to claim 1, characterized in that, The reducing gas contains a reducing component, which is one or a combination of H2, NH3 and CO.
3. The preparation method according to claim 1, characterized in that, The host solid material further includes a support, on which the host metal is loaded. The host metal is dispersed in one or a combination of single-atom, diatomic, or nanoparticle forms. When the host metal is dispersed in the form of a single atom, the composite metal catalyst contains a diatomic structure consisting of a migrating metal and a host metal. And / or, When the dispersion form of the host metal is diatomic, the composite metal catalyst contains n atoms composed of the migrating metal and the host metal, where n≥3; And / or, When the host metal is dispersed in the form of nanoparticles, the composite metal catalyst contains new nanoparticles composed of migrating metal and host metal, wherein the new nanoparticles are one or a combination of intermetallic compounds, metal solid solutions, and disordered metal alloys.
4. The preparation method according to claim 1, characterized in that, A process for preparing composite metal catalysts is described using a reactor, which is one or a combination of a fluidized bed, a stirred bed, and a fixed bed. The preparation process includes the following steps. S1. The guest solid material and the host solid material are loaded into the reactor, and a reducing gas is introduced into the reactor; S2. The guest solid material and the host solid material are subjected to heat treatment; S3. After heat treatment, the main solid phase material is separated to obtain the composite metal catalyst.
5. The preparation method according to claim 1 or 3, characterized in that, The carrier in the main solid phase material is one or a combination of metal oxides, carbon carriers, and molecular sieves.
6. The preparation method according to claim 3, characterized in that, The molar ratio of the migrating metal to the host metal in the intermetallic compound nanoparticles is 0.5 to 1.
5.
7. The preparation method according to claim 1, characterized in that, The guest solid material and the host solid material have different particle sizes. After migration heat treatment, the guest solid material and the host solid material are separated by particle sieving.