WO2020252774A1 - Supported catalyst having active metal atomically dispersed in support, and preparation method therefor and use thereof - Google Patents

Abstract

Disclosed is a supported catalyst having an active metal atomically dispersed in a support, comprising an active metal species and a metal oxide support, wherein the active metal comprises one or more of Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, W, Ir, Pt, and Au, and the metal in the support comprises one or more of Ti, Zr, Nb, Ce, Al, Ga, In, Si, Ge, and Sn. Also disclosed are a preparation method for said catalyst and a use thereof. The supported catalyst having an active metal atomically dispersed in a support is prepared in the present invention by means of in-situ generation in the support, wherein no aggregated particles of the active metal species have a particle size of greater than 1 nm. The preparation method uses inexpensive raw materials, involves simple reaction operations, has a high-level of safety, requires no post-treatment steps, and is scalable for industrial production. In addition, the present invention has wide applications and can be used to further scientific research and expand production with regard to different catalysis systems.

Description

Supported catalyst in which active metal is dispersed at atomic level in carrier and preparation method and application thereof Technical field

The invention belongs to the field of new material preparation, and in particular relates to a supported catalyst in which active metals are dispersed at the atomic level in a carrier, and a preparation method and application thereof.

Background technique

It is generally believed that sub-nano clusters have better catalytic activity or selectivity than nanoparticles and bulk materials, because when the particle dispersion reaches a single atom size, it causes many new characteristics, such as a sharp increase in surface free energy, Quantum size effect, unsaturated coordination environment and metal-carrier interaction, etc. In theory, the ideal state of supported metal catalyst dispersion is that the metal is uniformly distributed on the carrier in the form of single atoms. Compared with nano-scale supported catalysts, each metal atom of the atomic-level catalyst is used as an active site, which greatly improves the catalytic efficiency. Especially for the more expensive metals, atomizing the active catalytic components can greatly reduce the amount of catalyst used, reduce the cost of the catalyst, and increase the potential of the catalyst for large-scale application in industrial production.

At present, atomic-level supported catalysts have been used in CO oxidation and selective oxidation, hydrogenation and selective hydrogenation, NO reduction and oxidation, water gas shift, organic synthesis, methanol steam reforming, fuel cells, photoelectric catalysis, formaldehyde oxidation, etc. The field shows greater advantages. However, single-atom or cluster-level catalysts also have obvious shortcomings. When the metal particles are reduced to the atomic level, the specific surface area increases sharply, resulting in a sharp increase in the free energy of the metal surface. Agglomeration and coupling are prone to occur during preparation and reaction to form larger particles, which leads to a significant decrease in catalyst activity. Therefore, preparation physicochemical Atom-scale supported catalysts with stable properties face greater challenges.

At present, the preparation methods of atomically dispersed supported catalysts are mainly divided into the following types: co-precipitation method, immersion method, atomic layer deposition method, reverse Ostward maturation method, solid phase melting method, etc. In general, the above methods can effectively prepare atomic-level dispersed supported catalysts, but most methods involve severe synthesis conditions, expensive drugs and raw materials, and complex post-treatment processes, which greatly limit the atomic-level dispersed supported catalysts. Application in production practice.

The invention creatively starts from cost control, uses economical metal source materials and formamide, and realizes the universality of low-cost, large-scale and large-scale preparation of atomic-level dispersed metal-supported catalysts by designing simple reaction synthesis paths preparation.

Summary of the invention

The first aspect of the present invention provides a supported catalyst in which active metals are dispersed at the atomic level in a carrier, which comprises:

Active metal species;

Carrier metal oxide;

Wherein the active metal includes one or more of Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, W, Ir, Pt, Au, and the carrier metal includes One or more of Ti, Zr, Nb, Ce, Al, Ga, In, Si, Ge, Sn.

Preferably, the active metal is bonded with oxygen atoms on the surface of the support metal oxide.

Preferably, the active metal species and/or the support metal oxide are at least partially sulfided, nitrided, phosphatized or boronized. Accordingly, at least part of the active metal and the sulfur on the surface of the support metal oxide , Nitrogen, phosphorus or boron atoms are bonded.

Preferably, there are no aggregated particles of the active metal species with a particle size greater than 1 nm.

The second aspect of the present invention provides a preparation method of the supported catalyst in which the active metal described in the first aspect is dispersed at the atomic level in a carrier, which comprises the following steps:

1) Dissolving at least one metal salt of the first type and at least one metal salt of the second type in formamide, the first metal salt and the formamide undergo a complex reaction to obtain a formamide solution of mixed metal salt; wherein, The metal element in the first type of metal salt is one of Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, W, Ir, Pt, Au; The metal element in the second type of metal salt is one of Ti, Zr, Nb, Ce, Al, Ga, In, Si, Ge, and Sn;

2) React the formamide solution of the mixed metal salt obtained in step 1) at 100-300°C for 1 to 99 hours to cause the formamide to polymerize, and the by-product water of the formamide polymerization reaction and the second type of metal salt are hydrolyzed reaction;

3) Carry out the solid-liquid separation of the reaction mixture in step 2), and calcinate the obtained solid substance in an air atmosphere at a temperature of 300-900° C. for 1 to 99 hours to obtain the supported catalyst.

Preferably, in step 1), the total concentration of the first type metal salt in formamide is 0.001-0.1 mol/L, and the total concentration of the second type metal salt in formamide is 0.009-1.0 mol/L.

Preferably, it further includes step 4): at least partially nitriding, sulfidizing, phosphating or boronizing the supported catalyst obtained in step 3).

Wherein, "at least partially nitriding, sulfidizing, phosphating or boronizing" refers to controlling the degree of progress of the nitriding, sulfidizing, phosphating or boronizing reaction, in the supported catalyst obtained in step 3) The carrier metal oxide is at least partially replaced with one of carrier metal nitride, carrier metal sulfide, carrier metal phosphide, and carrier metal boride. Accordingly, at least part of the active metal and carrier metal oxide Sulfur, nitrogen, phosphorus or boron atoms on the surface are bonded.

Preferably, the nitridation is to use a nitrogen source to react with the supported catalyst obtained in step 3), wherein the nitrogen source includes ammonia gas, ammonia water, sodium amide, and sodium azide;

Said vulcanization is to use a sulfur source to react with the supported catalyst obtained in step 3), wherein the sulfur source includes sulfur powder, sodium sulfide, hydrogen sulfide, thioacetamide, and thiourea;

The phosphating is to use a phosphorus source to react with the supported catalyst obtained in step 3), wherein the phosphorus source includes phosphorus powder, phosphoric acid, alkali metal phosphate, and triphenylphosphine;

The boronization is to use a boron source to react with the supported catalyst obtained in step 3), wherein the boron source includes boron powder, boric acid, and alkali metal borate.

Preferably, the liquid phase means includes flask heating and hydrothermal reaction kettle heating, and the gas phase means includes tube furnace heating.

Preferably, the mixing method includes manual shaking, mechanical shaking, ultrasound, and stirring.

Preferably, the reaction vessel in step 1) and step 2) is a safe vessel with good heat resistance, including a flask and a polytetrafluoroethylene reactor.

Preferably, the method of solid-liquid separation includes centrifugation, filtration, and static sedimentation.

In the above step 2), the formamide self-polymerizes and carbonizes to form a nitrogen-carbon material, in which the nitrogen element will oriented chelate the first type of metal cations, so that the first type of metal ions are distributed on the nitrogen-carbon in an atomically dispersed state On the material, an active metal nitrogen-carbon material is formed. The by-product water generated during the polymerization and carbonization of formamide reacts with the second type of metal ions to form corresponding carrier oxides or hydroxides.

The above two reactions occur simultaneously, forming a rich interface between the active metal nitrogen-carbon material and the carrier metal oxide or hydroxide. Therefore, the atomically dispersed active metal nitrogen-carbon material forms a uniform and compact load on the in-situ generated carrier metal oxide or hydroxide base material, which is the supported catalyst precursor.

In the above step 3), the supported catalyst precursor is calcined in an air atmosphere to generate metal oxides from the metal hydroxide, and at the same time remove the nitrogen and carbon materials, and transfer the force of stabilizing the atomic-level active metal components to the support oxide At the interface, during the calcination process, the nitrogen-carbon material has a strong anchoring effect on the surrounding active metal atoms, which greatly delays the agglomeration of the active metal components. When the active metal is bonded with the oxygen atoms on the surface of the carrier metal oxide , That is, a supported catalyst in which the active metal is dispersed in the carrier at the atomic level is obtained.

The third aspect of the present invention provides the use of the supported catalyst in which the active metal of the first aspect is dispersed at the atomic level in the carrier, including: applicable to all non-electric reactions, such as hydrogenation, dehydrogenation, and isomerization Reaction, desulfurization reaction, catalytic polymerization reaction, etc.

The difference between the preparation method of the present invention and the dipping method is as follows:

The present invention uses a two-step method to achieve atomic-level high-dispersion loading of a wide range of metal elements on a variety of substrates. In the first step, first, the atomic-level dispersed active metal nitrogen-carbon material generates in-situ carrier metal oxide or hydroxide substrate Form a uniform and tight load on the material;

In the second step, in the process of roasting to remove the nitrogen and carbon, the nitrogen-carbon material has an anchoring effect on the active metal atoms. Before the active metal component is stabilized by the carrier oxide, the agglomeration of the active metal component is largely delayed and continues The atomic level dispersion state of the active metal is maintained, and finally the active metal is dispersed on the carrier metal oxide at the atomic level.

However, the traditional impregnation method usually achieves atomic-level adsorption at low temperature. After heating and roasting, the active metal migrates seriously. Because there is no force to delay the aggregation of active metal components during the roasting process, the active metal cannot be on the support metal oxide. In an atomic-level dispersion state, the final active metal is in the form of aggregated nano-, micro-, or even millimeter-level particles.

The beneficial effects of the present invention are as follows:

(1) The present invention prepares a supported catalyst in which the active metal is dispersed at the atomic level in the carrier by the method of in-situ generation of the carrier, wherein there are no aggregated particles of the active metal species with a particle size greater than 1 nm. The raw material cost is low, the reaction operation is simple, and the safety is high, and no post-processing step is required, which is conducive to industrial scale-up production. At the same time, it has a wide range of applications, which facilitates scientific research and expansion of production for different catalytic systems.

(2) The catalyst of the present invention has high mechanical strength, high dispersion of active components, high catalytic activity, and high selectivity. Compared with similar non-atomic dispersed catalysts, it is easier to be reduced.

Description of the drawings

Fig. 1 is a transmission electron micrograph of Ni/Al ₂ O ₃ prepared in Example 1 of the present invention.

Fig. 2 is a transmission electron microscope photograph of Ni/CeO ₂ prepared in Example 2 of the present invention.

Fig. 3 is a transmission electron microscope photograph of Ni/Al ₂ O ₃ prepared in Example 3 of the present invention.

Fig. 4 is a transmission electron microscope photograph of Ni/Al ₂ O ₃ prepared in Example 4 of the present invention.

Fig. 5 is a transmission electron micrograph of Ni/Al ₂ O ₃ prepared in Example 5 of the present invention.

Fig. 6 is a transmission electron microscope photo of Co/Al ₂ O ₃ prepared in Example 6 of the present invention.

Figure 7 is a transmission electron micrograph of Cu/Al ₂ O ₃ prepared in Example 7 of the present invention

Fig. 8 is a transmission electron microscope photograph of Au/Al ₂ O ₃ prepared in Example 8 of the present invention.

Fig. 9 is a transmission electron microscope photograph of Pd/Al ₂ O ₃ prepared in Example 9 of the present invention.

Fig. 10 is a transmission electron microscope photograph of CuZrO ₂ prepared in Example 10 of the present invention.

Fig. 11 is a transmission electron microscope photograph of Ni-W/Al ₂ O ₃ prepared in Example 11 of the present invention.

Fig. 12 is a scanning photograph of the element surface of Ni-W/Al ₂ O ₃ prepared in Example 11 of the present invention.

Figure 13 is an X-ray diffraction pattern of the Al ₂ O ₃ supported single-atom catalyst prepared in Examples 1, 3-9, and 11 of the present invention.

14 is a nitrogen adsorption and desorption curve of Ni/Al ₂ O ₃ prepared in Example 1 of the present invention, where De. represents the desorption curve, and Ab. represents the adsorption curve.

15 is the XPS Ni2p peak split curve of Ni/Al ₂ O ₃ prepared in Example 1 of the present invention.

Figure 16 is an X-ray diffraction pattern of Co/MoO ₃ prepared in Example 12 of the present invention.

Fig. 17 is an X-ray diffraction pattern of Co/MoS ₂ prepared in Example 12 of the present invention.

Fig. 18 shows the performance evaluation of Ni/Al ₂ O ₃ prepared in Example 1 of the present invention in the reaction of CO ₂ hydrogenation to methane.

Preparation Example 2 19 Ni embodiment of the present invention / CeO _{2 2} Performance Evaluation in CO hydrogenation reaction of methane.

20 is a hydrogen temperature program reduction curve of Ni/CeO ₂ prepared in Example 2 of the present invention.

Detailed ways

The content of the present invention will be further described below through specific embodiments.

Example 1

Put 60.0 mL of a formamide solution containing 0.009 mol/L anhydrous NiCl ₂ and 0.091 mol/L anhydrous AlCl ₃ in a polytetrafluoroethylene reactor with a volume of 100.0 mL, and react at 180° C. for 12 hours. After the reaction time expires, cool down naturally, take out the solid-liquid mixture, separate the solid-liquid by centrifugation, dry the solid in an oven at 80°C, collect the dry powder, and use a muffle furnace to roast at 450°C for 3 hours to obtain the target product Ni/Al ₂ O ₃ , the transmission electron microscope photo is shown in Figure 1, the nitrogen adsorption and desorption curve is shown in Figure 14, and the XPS Ni2p peak splitting curve is shown in Figure 15.

Example 2

Except that the type B salt anhydrous AlCl _{3 is} replaced with Ce(NO ₃ ) ₂ ·6H ₂ O, the others are the same as in Example 1, and the target product Ni/CeO ₂ is obtained. The transmission electron microscope photo is shown in Figure 2.

Example 3

Except that the concentration of anhydrous NiCl ₂ is increased to 0.018 mol/L, and the concentration of AlCl ₃ is increased to 0.182 mol/L, the others are the same as in Example 1. The target product Ni/Al ₂ O _{3 is obtained} . The transmission electron microscope photo is shown in Figure 3.

Example 4

Except that the concentration of anhydrous NiCl ₂ was increased to 0.027 mol/L, and the concentration of AlCl _{3 was} increased to 0.273 mol/L, the others were the same as in Example 1, and the target product Ni/Al ₂ O _{3 was obtained} . The transmission electron microscope photo is shown in Figure 4.

Example 5

Except that the muffle furnace calcination temperature and time were adjusted to 550°C and 3 hours respectively, the others were the same as in Example 1, and the target product Ni/Al ₂ O _{3 was obtained} . The transmission electron microscope photo is shown in Figure 5.

Example 6

Except that the type A metal salt anhydrous NiCl _{2 is} replaced with anhydrous CoCl ₂ , the other is the same as in Example 1, and the target product Co/Al ₂ O _{3 is obtained} . The same transmission electron microscope photo is shown in Figure 6.

Example 7

Except that the type A metal salt anhydrous NiCl _{2 is} replaced with anhydrous Cu(NO ₃ ) ₂ , the others are the same as in Example 1, and the target product Cu/Al ₂ O _{3 is obtained} . The transmission electron microscope photo is shown in Figure 7.

Example 8

Except that the type A metal salt anhydrous NiCl _{2 is} replaced with anhydrous AuCl ₃ , the others are the same as in Example 1, and the target product Au/Al ₂ O _{3 is obtained} . The transmission electron microscope photo is shown in Figure 8.

Example 9

Except that the type A metal salt anhydrous NiCl _{2 is} replaced with anhydrous PdCl ₃ , the others are the same as in Example 1, and the target product Pd/Al ₂ O _{3 is obtained} . The transmission electron microscope photo is shown in Figure 9.

Example 10

Except that the type A metal salt anhydrous NiCl _{2 is} replaced with anhydrous Cu(NO ₃ ) ₂ , and the type B salt anhydrous AlCl _{3 is} replaced with Zr(SO ₄ ) ₂ , the others are the same as in Example 1. The target product Cu/ ZrO ₂ , the transmission electron microscope photo is shown in Figure 10.

Example 11

The type A metal salt is extended to a dual active metal system, except that half of the concentration of NiCl ₂ as the type A metal salt is replaced with an equimolar concentration of anhydrous WCl ₃ , the others are the same as in Example 1, and the target product Ni-W is obtained. /Al ₂ O ₃ , the TEM photo is shown in Figure 11, and the element surface scan photo is shown in Figure 12.

Characterize and analyze the products obtained in Examples 1-12:

Where M _A represents the first type of metal, and M _B represents the second type of metal.

Transmission electron microscopy photos (Figures 1, 3-10, 11) show that the morphology of the M _A /Al ₂ O ₃ supported catalyst synthesized by using formamide, AlCl ₃ and different transition metal salts is granular, with an average Al ₂ O ₃ The particle size is within 5-10nm. Under ordinary high-resolution transmission, no aggregated particles of active metal species with a particle size greater than 1nm are seen.

The transmission electron micrograph (figure 2) shows that the morphology of the Ni/M _B O _x supported catalyst synthesized by using formamide, NiCl ₂ and the precursor metal salts of different supports is granular, and the average particle size of M _B O _x is 5 Within -10nm, under ordinary high-resolution transmission, there are no Ni aggregated particles with a particle size greater than 1nm.

TEM element surface scanning photo (Figure 12) shows: Ni-W/Al ₂ O ₃ supported catalyst particles synthesized by using formamide, NiCl ₂ , WCl ₃ and AlCl ₃ , Ni and W active metal components are uniformly distributed and No particle formation.

The X-ray powder diffraction pattern (Figure 13) shows that: in the examples 1-12 included in the present invention, only the diffraction peak of the carrier material was detected, and the diffraction peak of the active metal component was not seen, which proves that the active metal species is sub-nanometer Or the existence of clusters means that it is in a state of atomic dispersion.

The specific surface area test (figure 14 nitrogen absorption and desorption curve) shows that the specific surface area of the Ni/Al ₂ O ₃ supported catalyst synthesized using formamide, NiCl ₂ and AlCl ₃ is 407 m ² /g, and the pore morphology is dominated by wedge-shaped pores.

The XPS Ni2p peak curve (Figure 15) shows that the Ni component of the Ni/Al ₂ O ₃ supported catalyst synthesized using formamide, NiCl ₂ and AlCl _{3 is} bonded to the oxygen atom on the surface of the support metal oxide, and there is no zero The valence metal aggregation state exists.

Example 12

Place 60.0 mL of a formamide solution containing 0.009 mol/L anhydrous CoCl ₂ (M _A type metal salt) and 0.091 mol/L anhydrous MoCl ₃ (M _B type salt) in a volume of 100.0 mL of polytetrafluoroethylene In the reactor, react at 180°C for 12 hours. After the reaction time expires, the temperature is naturally cooled, the solid-liquid mixture is taken out, the solid-liquid mixture is separated by centrifugation, the solid is dried in an oven at 80°C, the dry powder is collected, and calcined in a muffle furnace at 450°C for 3 hours to obtain active metal The support metals are all supported catalysts Co/MoO _{3 in the} form of oxides. After stirring this product in 30 mL of thiourea aqueous solution for 0.5 h, it was placed in a reaction kettle with a volume of 50.0 mL and reacted at 220° C. for 18 h. After the reaction time expires, the temperature is naturally lowered, the solid-liquid mixture is taken out, the solid-liquid mixture is separated by centrifugation, the solid is placed in a 60°C oven and vacuum dried, and the dried powder is collected to obtain the target product Co/MoS ₂ supported catalyst. The support metal oxide is completely replaced with a support metal sulfide, and the active metal is bonded to the sulfur atom on the surface of the support metal sulfide. Figure 16 is an X-ray diffraction pattern of Co/MoO ₃ prepared in this embodiment. Figure 17 is an X-ray diffraction pattern of Co/MoS ₂ prepared in this embodiment.

Example 13

The Ni/Al ₂ O ₃ and Ni/CeO ₂ supported catalysts synthesized in Examples 1 and 2 were used to catalyze the CO ₂ hydrogenation reaction. The test conditions were as follows: the obtained catalyst was ground and pressed into particles of 20-60 mesh. The filling amount of the adsorbent is 0.5 g, the pre-reduction temperature is 450° C., the pressure is 0.1 MPa, the hydrogen flow rate is 30 mL/min, and the reduction time is half an hour. CO ₂ hydrogenation evaluation conditions: temperature 200-350℃, normal pressure, after the temperature stabilizes, react for 1 hour, take the product every 10 minutes and analyze the product by gas chromatography. The reaction gas is a mixed gas of CO ₂ and H ₂ and the mixing ratio is CO ₂ :H ₂ =1:4.

conclusion as below:

At reaction temperatures of 200°C, 230°C, 260°C, 290°C, 320°C, and 350°C, the catalytic selectivities of Ni/Al ₂ O ₃ are 85.86%, 84.48%, 85%, 90.56%, 100%, respectively. 100%, see Figure 18. At the test temperatures of 200°C, 230°C, and 260°C, the catalytic selectivity of Ni/CeO ₂ is 96.85%, 99.99%, and 100%, respectively, see Figure 19. Therefore, both catalysts show good catalytic selectivity.

Example 14

The hydrogen temperature program reduction test was used to characterize the Ni/CeO ₂ supported catalyst synthesized in Example 2. There were three sets of reduction peaks in the characterization results (Figure 20): they were at 270°C, 326°C and 434°C, of which 326°C is The reduction peak of nickel oxide on the surface of the support. Comparing the literature, there are five groups of reduction peaks in the hydrogen temperature program reduction data results of the Ni/CeO ₂ supported catalyst prepared with Ni particles supported on CeO ₂ and they are respectively at 210℃, 265℃, 360℃, 500℃ and 582 ℃(Morphology dependence of catalytic properties of Ni/CeO ₂ for CO ₂ methanation:A kinetic and mechanism study[J].Catalysis Today,2018,DOI:10.1016/j.cattod.2018.04.067.). 360°C is the reduction peak of nickel oxide on the surface of the support. The comparison with this catalyst shows that the atomically dispersed Ni/CeO ₂ supported catalyst synthesized in Example 2 is easier to be activated and reduced.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention. It should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (9)

1. A supported catalyst in which active metals are dispersed at the atomic level in a carrier is characterized in that it comprises:

   Active metal species;

   Carrier metal oxide;

   Wherein the active metal includes one or more of Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, W, Ir, Pt, Au, and the carrier metal includes One or more of Ti, Zr, Nb, Ce, Al, Ga, In, Si, Ge, Sn.
2. The supported catalyst according to claim 1, wherein the active metal is bonded to oxygen atoms on the surface of the support metal oxide.
3. The supported catalyst according to claim 1, wherein the active metal species and/or the support metal oxide are at least partially sulfided, nitrided, phosphatized or boronized, and correspondingly, at least partially The active metal is bonded with sulfur, nitrogen, phosphorus or boron atoms on the surface of the support metal oxide.
4. The supported catalyst according to claim 1 or 2, wherein there are no aggregated particles of the active metal species with a particle size greater than 1 nm.
5. The method for preparing a supported catalyst in which active metals are dispersed at an atomic level in a carrier according to claim 1, characterized in that it comprises the following steps:

   1) Dissolving at least one metal salt of the first type and at least one metal salt of the second type in formamide, the first metal salt and the formamide undergo a complex reaction to obtain a formamide solution of mixed metal salt; wherein, The metal element in the first type of metal salt is one of Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, W, Ir, Pt, Au; The metal element in the second type of metal salt is one of Ti, Zr, Nb, Ce, Al, Ga, In, Si, Ge, and Sn;

   2) React the formamide solution of the mixed metal salt obtained in step 1) at 100-300°C for 1 to 99 hours to cause the formamide to polymerize, and the by-product water of the formamide polymerization reaction and the second type of metal salt are hydrolyzed reaction;

   3) Carry out the solid-liquid separation of the reaction mixture in step 2), and calcinate the obtained solid substance in an air atmosphere at a temperature of 300-900° C. for 1 to 99 hours to obtain the supported catalyst.
6. The method for preparing a supported catalyst according to claim 5, wherein in step 1), the total concentration of the first type of metal salt in formamide is 0.001-0.1 mol/L, and the second type of metal salt is in formamide. The total concentration in amide is: 0.009-1.0mol/L.
7. The method for preparing a supported catalyst according to claim 5, further comprising step 4): subjecting the supported catalyst obtained in step 3) to at least partially nitriding, sulfidizing, phosphating or boronizing.
8. The preparation method according to claim 7, characterized in that the nitridation is to use a nitrogen source to react with the supported catalyst obtained in step 3), wherein the nitrogen source includes ammonia, ammonia, sodium amide, sodium azide ；

   Said vulcanization is to use a sulfur source to react with the supported catalyst obtained in step 3), wherein the sulfur source includes sulfur powder, sodium sulfide, hydrogen sulfide, thioacetamide, and thiourea;

   The phosphating is to use a phosphorus source to react with the supported catalyst obtained in step 3), wherein the phosphorus source includes phosphorus powder, phosphoric acid, alkali metal phosphate, and triphenylphosphine;

   The boronization is to use a boron source to react with the supported catalyst obtained in step 3), wherein the boron source includes boron powder, boric acid, and alkali metal borate.
9. The use of the supported catalyst according to claim 1 in catalyzing CO ₂ hydrogenation reactions.

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