CN112569963A

CN112569963A - Catalyst, method for forming the same and method for removing volatile organic compounds

Info

Publication number: CN112569963A
Application number: CN201911105510.4A
Authority: CN
Inventors: 李承轩; 颜绍仪; 赖宇伦
Original assignee: Industrial Technology Research Institute ITRI
Current assignee: Industrial Technology Research Institute ITRI
Priority date: 2019-09-27
Filing date: 2019-11-13
Publication date: 2021-03-30
Anticipated expiration: 2039-11-13
Also published as: CN112569963B; TW202112443A; TWI733200B

Abstract

A method of forming a catalyst, comprising: providing a neutral aqueous solution of salts of noble metals and salts of transition metals; dispersing a mesoporous template in a non-polar solvent to form a dispersion; mixing the neutral aqueous solution with the dispersion to form a mixed solution; heating the mixed solution to remove the non-polar solvent and water in the mixed solution and form powder; sintering the powder to form a catalyst in the holes of the mesoporous template; and removing the mesoporous template to retain the catalyst, wherein the catalyst comprises: a mesoporous transition metal oxide; and a monoatomic noble metal anchored to the mesoporous transition metal oxide.

Description

Catalyst, method for forming the same and method for removing volatile organic compounds

Technical Field

The invention relates to a monatomic noble metal catalyst, a method for forming the same, and applications thereof.

Background

In recent years, the problem of air pollution caused by Volatile Organic Compounds (VOCs) has been receiving attention. The major methods for removing volatile organic compounds are adsorption, incineration, photocatalysis, and catalytic oxidation, with catalytic oxidation being the most effective method for removing VOCs. The catalytic oxidation process uses catalyst active components of micron or nanometer size, and less monoatomic metal anchored on the carrier. Therefore, there is a need to develop a new monatomic catalyst and a method for forming the same, which can be applied to a catalytic oxidation process for removing VOCs.

Disclosure of Invention

An embodiment of the present invention provides a catalyst, including: a mesoporous transition metal oxide; and a monatomic noble metal anchored on the mesoporous transition metal oxide, wherein the transition metal comprises Co, Mn, Fe, Ni, Ce or a combination thereof, and the monatomic noble metal is Pt, Rh, Pd or Ru; wherein when the monoatomic noble metal is Pt, the transition metal does not include Fe; wherein when the monoatomic noble metal is Ru, the transition metal does not include Ni or Ce.

In some embodiments, when the monoatomic noble metal is Pt, the transition metal includes Co, Mn, Ni, Ce, or a combination thereof.

In some embodiments, when the monoatomic noble metal is Rh, the transition metal includes Co, Mn, Fe, Ni, Ce, or a combination thereof.

In some embodiments, when the monoatomic noble metal is Pd, the transition metal includes Co, Mn, Fe, Ni, Ce, or a combination thereof.

In some embodiments, when the monoatomic noble metal is Ru, the transition metal includes Co, Mn, Fe, or a combination thereof.

In some embodiments, the weight ratio of mesoporous transition metal oxide to monoatomic noble metal is between 1: 0.002 to 1: 0.06.

The method for forming the catalyst provided by one embodiment of the invention comprises the following steps: providing a neutral aqueous solution of salts of noble metals and salts of transition metals; dispersing a mesoporous template in a non-polar solvent to form a dispersion; mixing the neutral aqueous solution with the dispersion to form a mixed solution; heating the mixed solution to remove the non-polar solvent and water in the mixed solution and form powder; sintering the powder to form a catalyst in the holes of the mesoporous template; and removing the mesoporous template to retain the catalyst, wherein the catalyst comprises: a mesoporous transition metal oxide; and a monoatomic noble metal anchored to the mesoporous transition metal oxide.

In some embodiments, the monoatomic noble metal is Pt, Rh, Pd, or Ru, and the transition metal comprises Co, Mn, Fe, Ni, Ce, or a combination thereof.

In some embodiments, the temperature of heating the mixed solution to remove the non-polar solvent and water from the mixed solution and form a powder is between 55 ℃ and 75 ℃.

In some embodiments, the temperature at which the powder is sintered to form the catalyst is between 280 ℃ and 350 ℃.

In some embodiments, the step of removing the mesoporous template to retain the catalyst employs an aqueous solution of hydrofluoric acid or sodium hydroxide.

An embodiment of the present invention provides a method for removing a volatile organic compound, including: introducing a mixed gas containing volatile organic compounds into a catalyst reactor to oxidize the volatile organic compounds into water and carbon dioxide, wherein the catalyst comprises: a mesoporous transition metal oxide; and a monoatomic noble metal anchored to the mesoporous transition metal oxide.

In some embodiments, the volatile organic compound comprises propane, isopropanol, acetone, toluene, propylene glycol methyl ether acetate, or combinations thereof.

Drawings

FIG. 1 is a schematic diagram of a method of forming a catalyst according to an embodiment of the invention;

FIG. 2 shows a catalyst Pt according to an embodiment of the present invention₁Scanning transmission electron microscope photograph of mesoporous cobalt oxide;

FIG. 3 shows a catalyst Pt according to an embodiment of the present invention₁Scanning transmission electron micrographs of mesoporous manganese oxide;

FIG. 4 shows Pt foil and Pt according to an embodiment of the present invention₁Extended X-ray absorption microstructure spectra of mesoporous manganese oxide;

FIG. 5 shows a catalyst Pt according to an embodiment of the present invention₁Scanning transmission electron microscope photograph of mesoporous iron oxide;

FIG. 6 shows a catalyst Pt according to an embodiment of the present invention₁Scanning transmission electron microscope photograph of mesoporous nickel oxide;

FIG. 7 shows a catalyst Pt according to an embodiment of the present invention₁Scanning transmission electron micrograph of mesoporous cerium oxide;

FIG. 8 shows an embodiment of the present invention, catalyst Rh₁Scanning transmission electron microscope photograph of mesoporous cobalt oxide;

FIG. 9 shows an embodiment of the present invention, catalyst Pd₁Scanning transmission electron microscope photograph of mesoporous cobalt oxide;

FIG. 10 shows catalyst Ru in accordance with an embodiment of the present invention₁Scanning transmission electron micrograph of/mesoporous cobalt oxide.

In the above drawings, the reference numerals have the following meanings:

11 center hole template

13 hole in the hole

15 mesoporous transition metal oxide

17 monoatomic noble metal

Detailed Description

An embodiment of the present invention provides a catalyst, including: a mesoporous transition metal oxide; and a monoatomic noble Metal anchored to the mesoporous transition Metal oxide, i.e., Strong Metal-to-support interaction between the monoatomic Metal Su and the supportpport Interaction). Mesopores are defined as pores with a width of more than 2nm and less than 50nm, see IUPAC, Complex of Chemical technology, 2^nded. (the "Gold Book"), Oxford (1997). In some embodiments, the transition metal of the mesoporous transition metal oxide comprises Co, Mn, Fe, Ni, Ce, or a combination thereof, and the monoatomic noble metal is Pt, Rh, Pd, or Ru. In some embodiments, when the monoatomic noble metal is Pt, the transition metal does not include Fe. In some embodiments, when the monoatomic noble metal is Ru, the transition metal does not include Ni or Ce. For example, when the monoatomic noble metal is Pt, the transition metal includes Co, Mn, Ni, Ce, or a combination thereof. When the monoatomic noble metal is Rh, the transition metal is Co, Mn, Fe, Ni, Ce or a combination of the above. When the monoatomic noble metal is Pd, the transition metal is Co, Mn, Fe, Ni, Ce, or a combination thereof. When the monatomic noble metal is Ru, the transition metal is Co, Mn, Fe, or a combination of the foregoing. In some embodiments, the weight ratio of mesoporous transition metal oxide to monoatomic noble metal is between 1: 0.002 to 1: 0.06. If the amount of the monoatomic noble metal is too low, it is impossible to form a highly reactive active site by monoatomic anchoring on the mesoporous transition metal oxide. If the amount of the monoatomic noble metal is too high, large-sized particles such as metal clusters (clusters) or nanoparticles (nanoparticles) are generated, resulting in a decrease in the number of active sites and activity. In some embodiments, the specific surface area of the catalyst is between 60m²G to 200m²The catalyst has an average pore size of 8nm to 20nm, and meets the definition of mesoporous materials in the technical field. Since the amount of mesoporous transition metal oxide is much higher than the amount of monoatomic noble metal, the mesoporous transition metal oxide will constitute the framework of the catalyst. In other words, the mesoporous transition metal oxide belongs to the mesoporous material.

The method for forming the catalyst provided by one embodiment of the invention comprises the following steps: neutral aqueous solutions of salts of noble metals and salts of transition metals are provided. For example, salts of transition metals such as cobalt salts (e.g., Co (NO)₃)₂·6H₂O、CoCl₂·6H₂O、CoSO₄·7H₂O or other suitable cobalt salt), manganese salt (such as Mn (NO)₃)₂·4H₂O、MnCl₂·4H₂O、MnSO₄·xH₂O or other suitable manganese salt), iron salts (e.g. Fe (NO)₃)₃·9H₂O、FeCl₃、FeSO₄·xH₂O or other suitable iron salt), nickel salt (such as Ni (NO)₃)₂·6H₂O、NiCl₂·6H₂O、NiSO₄·7H₂O or other suitable nickel salt), or cerium salt (such as Ce (NO)₃)₃·6H₂O、CeCl₃·7H₂O、Ce₂(SO₄)₃·8H₂O or other suitable cerium salt) in water to form an aqueous salt solution of the transition metal. In one embodiment, the concentration of the transition metal salt aqueous solution is between 0.1M and 5.0M. If the concentration of the aqueous salt solution of the transition metal is too low, the subsequent mesoporous structure is not complete. If the concentration of the transition metal salt aqueous solution is too high, a non-mesostructured metal oxide is formed.

Alternatively, salts of noble metals such as platinum (e.g. H)₂PtCl₆、Pt(NH₃)₂Cl₂、Na₂PtCl₆·6H₂O or other suitable platinum salt), palladium salt (such as H₂PdCl₄、Na₂PdCl₄Or other suitable palladium salts), rhodium salts (such as Na)₃RhCl₆、Rh(NO₃)₃Or other suitable rhodium salts), or ruthenium salts (such as RuCl₃·xH₂O、[Ru(NH₃)₆Cl₂Or other suitable ruthenium salt) in water to form an aqueous salt solution of the noble metal. In one embodiment, the concentration of the aqueous salt solution of the noble metal is between 0.001M and 0.05M. If the concentration of the aqueous salt solution of the noble metal is too low, a monoatomic atom cannot be formed on the carrier. If the concentration of the aqueous salt solution of the noble metal is too high, large-sized particles such as metal clusters (clusters) or nanoparticles (nanoparticles) are generated. Mixing the aqueous solution of transition metal salt with the aqueous solution of noble metal salt, and adding appropriate alkali such as sodium bicarbonate, sodium carbonate, and hydrogenAn aqueous solution of sodium oxide or potassium hydroxide, and an aqueous solution of the above salt is adjusted to neutral (pH 7). In one embodiment, the neutral aqueous solution may be stirred at room temperature for 1 to 5 hours to ensure uniform mixing of the ions in the aqueous solution. It is understood that the concentrations and amounts of the aqueous solution of the transition metal salt and the aqueous solution of the noble metal salt determine the weight ratio of the mesoporous transition metal oxide to the monatomic noble metal in the subsequently formed catalyst.

In another aspect, the mesoporous template may be dispersed in a non-polar solvent to form a dispersion. The mesoporous template can be KIT-6, SBA-15, SBA-16, MCM-41 or a combination thereof, which is silica with a network of pores. In one embodiment, the non-polar solvent is a solvent with a polarity between 0.05 and 4, such as toluene, n-hexane, or a combination thereof. If the polarity of the nonpolar solvent is too high, the metal ions are not easily diffused into the mesoporous template. In one embodiment, the weight ratio of the mesoporous template to the non-polar solvent is between 1: 5 and 1: 20. If the dosage of the nonpolar solvent is too low, the mesoporous template cannot be completely dispersed. If the amount of the nonpolar solvent is too high, diffusion of metal ions is not facilitated.

The neutral aqueous solution is then mixed with the dispersion to form a mixed solution. The above steps are important keys to the monatomic noble metal. For example, if (1) the transition metal salts are soluble in other polar solvents such as alcohols rather than water; and/or (2) the mesoporous template is directly added into a neutral saline solution without dispersing the mesoporous template in a nonpolar solvent, and the finally formed main catalyst is not a single-atom noble metal and may be mainly nanoparticles or metal clusters.

The mixture is then heated to remove the non-polar solvent and water from the mixture and form a powder. For example, the temperature of the heating step is between 55 ℃ and 75 ℃. If the heating temperature is too low, the solvent cannot be removed effectively. If the heating temperature is too high, the solvent is removed too quickly, which is not favorable for uniform diffusion of metal ions. The powder is then sintered to form a catalyst in the pores of the mesoporous template. In some embodiments, the temperature at which the powder is sintered to form the catalyst is between 280 ℃ and 350 ℃, and the time for this sintering step is between 2 and 12 hours. If the sintering temperature is too low and/or the sintering time is too short, the mesoporous metal oxide structure is incomplete. If the sintering temperature is too high and/or the sintering time is too long, the structure is disintegrated.

The mesoporous template is then removed to retain the catalyst. In some embodiments, the step of removing the mesoporous template to retain the catalyst employs an aqueous solution of hydrofluoric acid or sodium hydroxide. The aqueous solution of hydrofluoric acid or sodium hydroxide can remove the material of the mesoporous template such as silicon dioxide without damaging the catalyst. It should be noted that the catalyst of the present invention is not limited to the above-mentioned forming method, and those skilled in the art can select other suitable methods to form the above-mentioned catalyst according to the equipment.

One embodiment of the present invention provides a method for removing Volatile Organic Compounds (VOCs), comprising: the mixed gas containing the volatile organic compound is introduced into a reactor filled with the catalyst to oxidize the volatile organic compound into water and carbon dioxide. In some embodiments, the volatile organic compound comprises propane, isopropanol, acetone, toluene, propylene glycol methyl ether acetate, or combinations thereof. It can be seen from the following examples that the catalysts of the present invention, having a single noble metal anchored to the mesoporous transition metal oxide, can effectively reduce the temperature at which VOCs are oxidized to carbon dioxide and water. In summary, the present invention provides novel catalyst forms and compositions and methods for forming the same, which are useful for removing VOCs.

The method of forming the catalyst can be as shown in FIG. 1. In fig. 1, a mesoporous template 11 is dispersed in a non-polar solvent, and the mesoporous template 11 has mesopores 13. After the neutral aqueous solution of the salts of the noble metal and the transition metal is mixed with the dispersion liquid of the mesoporous template, the aqueous solution of the salts of the transition metal and the salts of the noble metal is filled into the mesoporous 13. The mixed solution is heated to remove water and nonpolar solvent, so that transition metal salts and noble metal salts in the mesopores 13 form mesopore transition metal oxide 15 and monoatomic noble metal 17, and the monoatomic noble metal 17 is anchored on the mesopore transition metal oxide 15. The mesoporous template 11 is then removed, leaving the mesoporous transition metal oxide 15 and the monatomic noble metal 17, with the monatomic noble metal 17 anchored to the mesoporous transition metal oxide 15.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail as follows:

examples

Example 1-1 (Pt)₁Cobalt oxide with middle hole

6.02g of Co (NO) was taken₃)₂·6H₂O was dissolved in 10.24mL of water to form an aqueous solution of the cobalt salt. Then H is put in₂PtCl₆After adding an aqueous solution of the above cobalt salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with an aqueous 1M NaOH solution, and stirred at room temperature for two hours.

5.12g of the mesoporous template KIT-6 (prepared by chem. Mater.2017, 29, 40-52.) was dispersed in 64mL of toluene, and the dispersion was stirred well to form a dispersion of KIT-6. Then, the KIT-6 dispersion was added to the aqueous solution, heated to 65 ℃ and stirred to slowly evaporate the water and toluene until a powder was formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then, the mesoporous template KIT-6 containing the catalyst in the pores is dispersed in 64mL of toluene, and the mixture is sufficiently stirred and dispersed to form a dispersion liquid of the mesoporous template KIT-6 containing the catalyst in the pores.

4g of Co (NO) was taken₃)₂·6H₂O was dissolved in 10mL of water to form an aqueous solution of cobalt salt. Then H is put in₂PtCl₆After addition of an aqueous solution of the above cobalt salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then putting catalyst in the middle hole templateKIT-6 is added into 2M NaOH solution, heated to 65 ℃ and stirred to remove the mesoporous template KIT-6. Thus, the resulting catalyst comprises mesoporous cobalt oxide, and monoatomic Pt anchored to the mesoporous cobalt oxide. FIG. 2 shows a scanning transmission electron micrograph of the catalyst. As can be seen from FIG. 2, the size of Pt (bright spot) is less than 1nm, and is equal to the theoretical diameter of Pt: (

) Similarly, it should be demonstrated that Pt anchored to mesoporous cobalt oxide is a single atom.

In accordance with Adsorption isotherms: the teaching of Gas Adsorption Equilibria, Springer, Boston, MA (2005) shows that the catalyst belongs to a mesoporous structure and has a specific surface area of 136.6m²Per g, pore volume of 0.52cm³G, and the width of the hole is 15.2 nm.

Examples 1-2 (Pt)₁Manganese oxide with mesoporous pores

5.19g of Mn (NO) was taken₃)₂·4H₂O was dissolved in 10.24mL of water to form an aqueous solution of manganese salt. Then H is put in₂PtCl₆After the addition of the above aqueous solution of manganese salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours.

5.12g of the mesoporous template KIT-6 was dispersed in 64mL of toluene and thoroughly stirred to form a dispersion of KIT-6. Then, the KIT-6 dispersion was added to the aqueous solution, heated to 65 ℃ and stirred to slowly evaporate the water and toluene until a powder was formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then, the mesoporous template KIT-6 containing the catalyst in the pores is dispersed in 64mL of toluene, and the mixture is sufficiently stirred and dispersed to form a dispersion liquid of the mesoporous template KIT-6 containing the catalyst in the pores.

Another 3.46g of Mn (NO) was taken₃)₂·4H₂O was dissolved in 10mL of water to form an aqueous solution of manganese salt. Then H is put in₂PtCl₆(50mM, 1.73mL) of the manganese salt aqueous solution was added, followed by 1M NaOH waterThe solution was adjusted to neutral (pH 7) and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous manganese oxide, and monoatomic Pt anchored to the mesoporous manganese oxide. FIG. 3 shows a scanning transmission electron micrograph of the catalyst. As can be seen from FIG. 3, the size of Pt (bright spot) is less than 1nm, and is equal to the theoretical diameter of Pt: (

) Similarly, it should be demonstrated that Pt anchored to mesoporous manganese oxide is a single atom. On the other hand, analysis of the catalyst by extended X-ray absorption microstructure (EXAFS) as shown in FIG. 4, which does not have the Pt-Pt signal, should prove that Pt anchored to mesoporous manganese oxide is separated by a certain distance, is monoatomic and does not aggregate.

In accordance with Adsorption isotherms: the teaching of Gas Adsorption Equilibria, Springer, Boston, MA (2005) shows that the catalyst belongs to a mesoporous structure, and the specific surface area of the catalyst is 61.5m²Per g, pore volume of 0.13cm³G, and the width of the hole is 8.7 nm.

Examples 1 to 3 (Pt)₁Mesoporous iron oxide

8.36g of Fe (NO) are taken₃)₃·9H₂O was dissolved in 10.24mL of water to form an aqueous solution of iron salt. Then H is put in₂PtCl₆After addition of an aqueous solution of the above iron salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours.

Another 5.57g of Fe (NO) was taken₃)₃·9H₂O was dissolved in 10mL of water to form an aqueous solution of iron salt. Then H is put in₂PtCl₆After addition of an aqueous solution of the above iron salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous iron oxide, and monoatomic Pt anchored to the mesoporous iron oxide. FIG. 5 shows a scanning transmission electron micrograph of the catalyst. As can be seen from FIG. 5, the size of Pt (bright spot) is less than 1nm, and is equal to the theoretical diameter of Pt: (

) Similarly, it should be demonstrated that Pt anchored to mesoporous iron oxide is a single atom.

In accordance with Adsorption isotherms: the teaching of Gas Adsorption Equilibria, Springer, Boston, MA (2005) shows that the catalyst belongs to a mesoporous structure and has a specific surface area of 194m²Per g, pore volume of 0.47cm³In terms of a/g, and the width of the hole was 9.6 nm.

Examples 1 to 4 (Pt)₁Mesoporous nickel oxide)

6.02g of Ni (NO) was taken₃)₂·6H₂O was dissolved in 10.24mL of water to form an aqueous solution of the nickel salt. Then H is put in₂PtCl₆After adding the above aqueous solution of nickel salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH solution, and stirred at room temperature for two hours.

Taking 4.01g of Ni (NO)₃)₂·6H₂O was dissolved in 10mL of water to form an aqueous solution of the nickel salt. Then H is put in₂PtCl₆After addition of the above aqueous solution of nickel salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous nickel oxide, and monoatomic Pt anchored to the mesoporous nickel oxide. FIG. 6 shows a scanning transmission electron micrograph of the catalyst. As can be seen from FIG. 6, the size of Pt (bright spot) is less than lnm, and is equal to the theoretical diameter of Pt: (

) Similarly, it should be possible to demonstrate anchoringPt on mesoporous nickel oxide is a single atom.

In accordance with Adsorption isotherms: the teaching of Gas Adsorption Equilibria, Springer, Boston, MA (2005) shows that the catalyst belongs to a mesoporous structure and has a specific surface area of 116m²Per g, pore volume of 0.55cm³In terms of a/g and a pore width of 18.6 nm.

Examples 1 to 5 (Pt)₁Mesoporous cerium oxide

8.98g of Ce (NO) was taken₃)₃·6H₂O was dissolved in 10.24mL of water to form an aqueous solution of cerium salt. Then H is put in₂PtCl₆After addition of an aqueous solution of the above cerium salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with an aqueous 1M NaOH solution, and stirred at room temperature for two hours.

An additional 5.99g of Ce (NO) was taken₃)₃·6H₂O was dissolved in 10mL of water to form an aqueous solution of cerium salt. Then H is put in₂PtCl₆After addition of an aqueous solution of the above cerium salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with an aqueous 1M NaOH solution and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding a mesoporous template KIT-6 containing a catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, stirring,to remove the mesoporous template KIT-6. Thus, the resulting catalyst comprises mesoporous ceria, and monoatomic Pt anchored to the mesoporous ceria. FIG. 7 shows a scanning transmission electron micrograph of the catalyst. As can be seen from FIG. 7, the size of Pt (bright spot) is less than 1nm, and is equal to the theoretical diameter of Pt: (

) Similarly, it should be demonstrated that Pt anchored to mesoporous ceria is a single atom.

In accordance with Adsorption isotherms: the teaching of Gas Adsorption Equilibria, Springer, Boston, MA (2005) shows that the catalyst belongs to a mesoporous structure, and the specific surface area of the catalyst is 135m²Per g, pore volume of 0.43cm³In terms of a/g, and the width of the hole was 12.8 nm.

Example 2-1 (Rh)₁Cobalt oxide with middle hole

6.02g of Co (NO) was taken₃)₂·6H₂O was dissolved in 10.24mL of water to form an aqueous solution of the cobalt salt. Then Na is added₃RhCl₆After adding an aqueous solution of the above cobalt salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with an aqueous 1M NaOH solution, and stirred at room temperature for two hours.

4g of Co (NO) was taken₃)₂·6H₂O was dissolved in 10mL of water to form an aqueous solution of cobalt salt. Then Na is added₃RhCl₆After addition of an aqueous solution of the above cobalt salt (50mM, 1.73mL), the solution was adjusted to neutrality (pH 7) with an aqueous 1M NaOH solution, and the mixture was stirred at room temperatureFor a period of time to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous cobalt oxide, and a monoatomic Rh anchor to the mesoporous cobalt oxide. FIG. 8 shows a scanning transmission electron micrograph of the catalyst. As can be seen from FIG. 8, Rh (bright spot) is smaller than 1nm in size and has a theoretical diameter of Rh (R) ((R))

) Similarly, it should be demonstrated that Rh anchored to mesoporous cobalt oxide is a single atom.

Example 2-2 (Rh)₁Manganese oxide with mesoporous pores

5.19g of Mn (NO) was taken₃)₂·4H₂O was dissolved in 10.24mL of water to form an aqueous solution of manganese salt. Then Na is added₃RhCl₆After the addition of the above aqueous solution of manganese salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours.

Another 3.46g of Mn (NO) was taken₃)₂·4H₂O was dissolved in 10mL of water to form an aqueous solution of manganese salt. Then Na is added₃RhCl₆After addition of an aqueous solution of the above manganese salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous manganese oxide, and a monoatomic Rh anchor to the mesoporous manganese oxide.

Examples 2 to 3 (Rh)₁Mesoporous iron oxide

8.36g of Fe (NO) are taken₃)₃·9H₂O was dissolved in 10.24mL of water to form an aqueous solution of iron salt. Then Na is added₃RhCl₆After addition of an aqueous solution of the above iron salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours.

Another 5.57g of Fe (NO) was taken₃)₃·9H₂O was dissolved in 10mL of water to form an aqueous solution of iron salt. Then Na is added₃RhCl₆After addition of an aqueous solution of the above iron salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous iron oxide, and a monoatomic Rh atom anchored to the mesoporous iron oxide.

Examples 2 to 4 (Rh)₁Mesoporous nickel oxide)

6.02g of Ni (NO) was taken₃)₂·6H₂O was dissolved in 10.24mL of water to form an aqueous solution of the nickel salt. Then Na is added₃RhCl₆After adding the above aqueous solution of nickel salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH solution, and stirred at room temperature for two hours.

Taking 4.01g of Ni (NO)₃)₂·6H₂O was dissolved in 10mL of water to form an aqueous solution of the nickel salt. Then Na is added₃RhCl₆After addition of the above aqueous solution of nickel salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous nickel oxide, and a monoatomic Rh atom anchored to the mesoporous nickel oxide.

Examples 2 to 5 (Rh)₁Mesoporous cerium oxide

8.98g of Ce (NO) was taken₃)₃·6H₂O was dissolved in 10.24mL of water to form an aqueous solution of cerium salt. Then Na is added₃RhCl₆After addition of an aqueous solution of the above cerium salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with an aqueous 1M NaOH solution, and stirred at room temperature for two hours.

An additional 5.99g of Ce (NO) was taken₃)₃·6H₂O was dissolved in 10mL of water to form an aqueous solution of cerium salt. Then Na is added₃RhCl₆After addition of an aqueous solution of the above cerium salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with an aqueous 1M NaOH solution and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous ceria, and a monoatomic Rh anchored to the mesoporous ceria.

Example 3-1(Pd₁Cobalt oxide with middle hole

6.02g of Co (NO) was taken₃)₂·6H₂O was dissolved in 10.24mL of water to form an aqueous solution of the cobalt salt. Then H is put in₂PdCl₄After adding an aqueous solution of the above cobalt salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with an aqueous 1M NaOH solution, and stirred at room temperature for two hours.

4g of Co (NO) was taken₃)₂·6H₂O was dissolved in 10mL of water to form an aqueous solution of cobalt salt. Then H is put in₂PdCl₄After addition of an aqueous solution of the above cobalt salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous Co₃O₄And Co anchored in the mesopores₃O₄The monoatomic Pd of (a). FIG. 9 shows a scanning transmission electron micrograph of the catalyst. As can be seen from FIG. 9, the size of Pd (bright spot) is less than 1nm,and the theoretical diameter of Pd: (

) Similarly, it should be possible to demonstrate anchoring to Co₃O₄The Pd on the group is a single atom.

Example 3-2(Pd₁Manganese oxide with mesoporous pores

5.19g of Mn (NO) was taken₃)₂·4H₂O was dissolved in 10.24mL of water to form an aqueous solution of manganese salt. Then H is put in₂PdCl₄After the addition of the above aqueous solution of manganese salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours.

Another 3.46g of Mn (NO) was taken₃)₂·4H₂O was dissolved in 10mL of water to form an aqueous solution of manganese salt. Then H is put in₂PdCl₄After addition of an aqueous solution of the above manganese salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous manganese oxide, and a monoatomic Pd anchored to the mesoporous manganese oxide.

Examples 3 to 3 (Pd)₁Mesoporous iron oxide

8.36g of Fe (NO) are taken₃)₃·9H₂O was dissolved in 10.24mL of water to form an aqueous solution of iron salt. Then H is put in₂PdCl₄After addition of an aqueous solution of the above iron salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours.

Another 5.57g of Fe (NO) was taken₃)₃·9H₂O was dissolved in 10mL of water to form an aqueous solution of iron salt. Then H is put in₂PdCl₄After addition of an aqueous solution of the above iron salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous iron oxide, and monatomic Pd anchored to the mesoporous iron oxide.

Examples 3 to 4 (Pd)₁Mesoporous nickel oxide)

6.02g of Ni (NO) was taken₃)₂·6H₂O dissolved in 10.24mL of waterIn (1), an aqueous solution of a nickel salt is formed. Then H is put in₂PdCl₄After adding the above aqueous solution of nickel salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH solution, and stirred at room temperature for two hours.

Taking 4.01g of Ni (NO)₃)₂·6H₂O was dissolved in 10mL of water to form an aqueous solution of the nickel salt. Then H is put in₂PdCl₄After addition of the above aqueous solution of nickel salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous nickel oxide, and a monoatomic Pd anchored to the mesoporous nickel oxide.

Examples 3 to 5 (Pd)₁Mesoporous cerium oxide

8.98g of Ce (NO) was taken₃)₃·6H₂O was dissolved in 10.24mL of water to form an aqueous solution of cerium salt. Then H is put in₂PdCl₄After addition of an aqueous solution of the above cerium salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with an aqueous 1M NaOH solution, and stirred at room temperature for two hours.

An additional 5.99g of Ce (NO) was taken₃)₃·6H₂O was dissolved in 10mL of water to form an aqueous solution of cerium salt. Then H is put in₂PdCl₄After addition of an aqueous solution of the above cerium salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with an aqueous 1M NaOH solution and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous ceria, and a monoatomic Pd anchored to the mesoporous ceria.

Example 4-1 (Ru)₁Cobalt oxide with middle hole

6.02g of Co (NO) was taken₃)₂·6H₂O was dissolved in 10.24mL of water to form an aqueous solution of the cobalt salt. Followed by the addition of RuCl₃After adding an aqueous solution of the above cobalt salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with an aqueous 1M NaOH solution, and stirred at room temperature for two hours.

4g of Co (NO) was taken₃)₂·6H₂O was dissolved in 10mL of water to form an aqueous solution of cobalt salt. Followed by the addition of RuCl₃After addition of an aqueous solution of the above cobalt salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous Co₃O₄And Co anchored in the mesopores₃O₄The monoatomic atom Ru of (a). FIG. 10 shows a scanning transmission electron micrograph of the catalyst. As can be seen from FIG. 10, the size of Ru (bright spot) is less than 1nm, and is consistent with the theoretical diameter of Ru (R) ((R))

) Similarly, it should be possible to demonstrate anchoring to Co₃O₄Ru in (b) is a single atom.

Example 4-2 (Ru)₁Manganese oxide with mesoporous pores

5.19g of Mn (NO) was taken₃)₂·4H₂O was dissolved in 10.24mL of water to form an aqueous solution of manganese salt. Followed by the addition of RuCl₃After the addition of the above aqueous solution of manganese salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours.

Another 3.46g of Mn (NO) was taken₃)₂·4H₂O was dissolved in 10mL of water to form an aqueous solution of manganese salt. Followed by the addition of RuCl₃After addition of an aqueous solution of the above manganese salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous manganese oxide and a monoatomic Ru anchored to the mesoporous manganese oxide.

Examples 4 to 3 (Ru)₁Mesoporous iron oxide

8.36g of Fe (NO) are taken₃)₃·9H₂O was dissolved in 10.24mL of water to form an aqueous solution of iron salt. Followed by the addition of RuCl₃After addition of an aqueous solution of the above iron salt (50mM, 2.6mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours.

Another 5.57g of Fe (NO) was taken₃)₃·9H₂O was dissolved in 10mL of water to form an aqueous solution of iron salt. Followed by the addition of RuCl₃After addition of an aqueous solution of the above iron salt (50mM, 1.73mL), the solution was adjusted to neutral (pH 7) with 1M aqueous NaOH and stirred at room temperature for two hours to form another aqueous solution.

Then adding the dispersion of the medium-pore template KIT-6 containing the catalyst in the pores into another aqueous solution, heating to 65 ℃ and stirring to slowly volatilize the water and the toluene until powder is formed. The powder was then calcined at 300 ℃ for 3 hours to form the catalyst in the pores of the mesoporous template KIT-6. Then adding the medium-pore template KIT-6 containing the catalyst in the pores into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the medium-pore template KIT-6. Thus, the resulting catalyst comprises mesoporous iron oxide, and monoatomic Ru anchored to the mesoporous iron oxide.

Comparative example 1 (mesoporous cobalt oxide)

6.02g of Co (NO) was taken₃)₂·6H₂O was dissolved in 10.24mL of water to form an aqueous solution of the cobalt salt. 5.12g of the mesoporous template KIT-6 (prepared by chem. Mater.2017, 29, 40-52.) was dispersed in 64mL of toluene, and the dispersion was stirred well to form a dispersion of KIT-6. Then, the KIT-6 dispersion was added to the aqueous solution, heated to 65 ℃ and stirred to slowly evaporate the water and toluene until a powder was formed. Followed by calcining the powder at 300 ℃ for 3 hours to form Co₃O₄In the holes of the mesoporous template KIT-6.

Then will contain Co₃O₄And adding the mesoporous template KIT-6 in the holes into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the mesoporous template KIT-6. Thus, the mesoporous cobalt oxide is obtained.

The mesoporous cobalt oxide of comparative example 1 and Pt of example 1-1 were used₁Mesoporous oxygenCobalt compound, Rh of example 2-1₁The XRD pattern of mesoporous cobalt oxide was measured after heating to 700 deg.C and calcining for 10 hours. By comparing the patterns before and after calcination, it was found that the mesoporous cobalt oxide of comparative example 1 and Pt of example 1-1₁Mesoporous cobalt oxide, Rh from example 2-1₁Both the mesoporous cobalt oxide and the mesoporous cobalt oxide can resist high temperature.

Example 5 (propane removal)

Rh from example 2-1 was taken₁Mesoporous cobalt oxide with Pt from example 1-1₁And/or grinding the cobalt oxide with the mesoporous, sieving and filling the cobalt oxide into a reaction tube, and performing a propane oxidation reaction test at different temperatures. The concentration of propane at the inlet of the reaction tube was 388ppm (corresponding to Rh monatomic) and 374ppm (corresponding to Pt monatomic), respectively, and the GHSV of propane was 6250h^-1. And (3) introducing propane into reaction tubes with different temperatures, measuring the concentration of the propane at the outlet of the reaction tubes, and determining the propane removal efficiency of the catalyst at different temperatures. Pt monoatomic T of example 1-1₅₀(i.e., a reaction temperature at which propane removal efficiency reaches 50%) was 147 ℃ and T of Rh monoatomic of example 2-1₅₀At 144 c, the oxidation catalytic activity of Rh monatomic is slightly higher than that of Pt monatomic. The propane removal efficiency of Rh monatomic at 175 ℃ was greater than 99%, while the propane removal efficiency of Pt monatomic at 180 ℃ was greater than 99%. It is noted that conventional catalysts (e.g., Pt/Al)₂O₃) T for propane₅₀Greater than or equal to 190 ℃. The catalyst of the above embodiment can greatly reduce T to propane as compared with the conventional catalyst₅₀To below 150 deg.c.

Comparative example 2 (mesoporous manganese oxide)

5.19g of Mn (NO) was taken₃)₂·4H₂O was dissolved in 10.24mL of water to form an aqueous solution of manganese salt. 5.12g of the mesoporous template KIT-6 (prepared by chem. Mater.2017, 29, 40-52.) was dispersed in 64mL of toluene, and the dispersion was stirred well to form a dispersion of KIT-6. Then, the KIT-6 dispersion was added to the aqueous solution, heated to 65 ℃ and stirred to slowly evaporate the water and toluene until a powder was formed. Followed by calcining the powder at 300 ℃ for 3 hours to form MnO₂In the holes of the middle hole template KIT-6In (1).

Then will contain MnO₂And adding the mesoporous template KIT-6 in the holes into a 2M NaOH solution, heating to 65 ℃, and stirring to remove the mesoporous template KIT-6. Thus, mesoporous manganese oxide is obtained.

Example 6-1 (removal of isopropanol)

The mesoporous manganese oxide of comparative example 2 was taken with Pt of examples 1-2₁And/or rolling, sieving, filling into a reaction tube, and performing isopropanol oxidation reaction tests at different temperatures. The isopropanol concentration at the inlet of the reaction tube was 224ppm and the GHSV was 17300h^-1. Introducing isopropanol into reaction tubes with different temperatures, measuring the concentrations of the isopropanol and the byproduct acetone at the outlets of the reaction tubes, and determining the efficiency of the catalyst for completely removing the isopropanol at different temperatures. Pt monoatomic T of examples 1 to 2₉₀(i.e., a reaction temperature at which isopropanol removal efficiency reaches 90%) was about 120 ℃ and T of the mesoporous manganese oxide of comparative example 2₉₀Is about 155 deg.c. It is noted that catalysts (e.g., Pt/Al) are known₂O₃) T for isopropyl alcohol₉₀Greater than or equal to 150 deg.C, or even greater than 200 deg.C. The catalyst of the above embodiment can reduce the T to isopropyl alcohol as compared with the conventional catalyst₉₀To below 120 ℃.

Example 6-2 (removal of isopropanol)

The Pt/mesoporous cobalt oxide of example 1-1, the Pt/mesoporous manganese oxide of example 1-2, the Pt/mesoporous iron oxide of example 1-3, and the Pt/mesoporous nickel oxide of example 1-4 were rolled, sieved, and filled in a reaction tube, and subjected to isopropanol oxidation reaction tests at different temperatures. The concentration of isopropanol at the inlet of the reaction tube was 234ppm (Pt/mesoporous cobalt oxide of example 1-1), 224ppm (Pt/mesoporous manganese oxide of example 1-2), 274ppm (Pt/mesoporous iron oxide of example 1-3) and 248ppm (Pt/mesoporous nickel oxide of example 1-4), respectively, and GHSV was 17300h^-1. Introducing isopropanol into reaction tubes with different temperatures, measuring the concentrations of the isopropanol and the byproduct acetone at the outlets of the reaction tubes, and determining the efficiency of the catalyst for completely removing the isopropanol at different temperatures. Pt monoatomic T of example 1-1₉₀(i.e. the efficiency of removing the isopropanol reaches 90 percentReaction temperature of) about 130 deg.C, Pt monoatomic T of example 1-2₉₀About 120 ℃ C, Pt monoatomic T of examples 1 to 3₉₀About 182 ℃ and the Pt monoatomic T of examples 1-4₉₀Is about 163 ℃. From the above, the effect of the monoatomic Pt anchored to the mesoporous cobalt oxide, mesoporous manganese oxide, and mesoporous nickel oxide is superior to that of the monoatomic Pt anchored to the mesoporous iron oxide.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A catalyst, comprising:

a mesoporous transition metal oxide; and

a monatomic noble metal anchored to the mesoporous transition metal oxide;

wherein the transition metal comprises Co, Mn, Fe, Ni, Ce or combinations thereof, and the monatomic noble metal is Pt, Rh, Pd or Ru; when the monoatomic noble metal is Pt, the transition metal does not include Fe;

when the monoatomic noble metal is Ru, the transition metal does not include Ni or Ce.

2. The catalyst of claim 1, wherein when the monatomic noble metal is Pt, the transition metal comprises Co, Mn, Ni, Ce, or combinations thereof.

3. The catalyst of claim 1, wherein when the monoatomic noble metal is Rh, the transition metal comprises Co, Mn, Fe, Ni, Ce, or a combination thereof.

4. The catalyst of claim 1, wherein when the monatomic noble metal is Pd, the transition metal comprises Co, Mn, Fe, Ni, Ce, or combinations thereof.

5. The catalyst of claim 1 wherein when the monatomic noble metal is Ru, the transition metal comprises Co, Mn, Fe, or combinations thereof.

6. The catalyst of claim 1 wherein the weight ratio of mesoporous transition metal oxide to monoatomic noble metal is between 1: 0.002 and 1: 0.06.

7. The catalyst according to claim 1, wherein the specific surface area of the catalyst is 60m²G to 200m²Between/g.

8. The catalyst of claim 1 wherein the catalyst has an average pore size of between 8nm and 20 nm.

9. A method of forming a catalyst, comprising:

providing a neutral aqueous solution of salts of noble metals and salts of transition metals;

dispersing a mesoporous template in a non-polar solvent to form a dispersion liquid;

mixing the neutral aqueous solution and the dispersion liquid to form a mixed solution;

heating the mixed solution to remove the non-polar solvent and water in the mixed solution and form powder;

sintering the powder to form a catalyst in the holes of the middle hole template; and

removing the mesoporous template to retain the catalyst,

wherein the catalyst comprises:

a mesoporous transition metal oxide; and

a monoatomic noble metal anchored to the mesoporous transition metal oxide.

10. The method of claim 9, wherein when the monatomic noble metal is Pt, Rh, Pd, or Ru, the transition metal comprises Co, Mn, Fe, Ni, Ce, or combinations thereof.

11. The method of claim 9, wherein the weight ratio of mesoporous transition metal oxide to the monoatomic noble metal is in the range of 1: 0.002 to 1: 0.06.

12. The method of claim 9, wherein the temperature for heating the mixture to remove the non-polar solvent and water from the mixture and form the powder is between 55 ℃ and 75 ℃.

13. The method of claim 9, wherein the temperature of sintering the powder to form the catalyst in the pores of the mesoporous template is between 280 ℃ and 350 ℃.

14. The method of claim 9, wherein the step of removing the mesoporous template to retain the catalyst uses an aqueous solution of hydrofluoric acid or sodium hydroxide.

15. A method of removing volatile organic compounds, comprising:

introducing a volatile organic compound into a catalyst to oxidize the volatile organic compound into water and carbon dioxide, wherein the catalyst comprises:

a mesoporous transition metal oxide; and

a monoatomic noble metal anchored to the mesoporous transition metal oxide.

16. The method of claim 15, wherein the monatomic noble metal is Pt, Rh, Pd, or Ru and the transition metal comprises Co, Mn, Fe, Ni, Ce, or combinations thereof.

17. The method of claim 15, wherein the weight ratio of mesoporous transition metal oxide to monoatomic noble metal is between 1: 0.002 and 1: 0.06.

18. The method of claim 15, wherein the volatile organic compound comprises propane, isopropanol, acetone, toluene, propylene glycol methyl ether acetate, or combinations thereof.