CN107866250B

CN107866250B - Preparation method of carbon-coated noble metal nano catalyst

Info

Publication number: CN107866250B
Application number: CN201610855734.7A
Authority: CN
Inventors: 代元元; 钟良枢; 孙予罕; 李正甲; 安芸蕾; 于飞; 林铁军; 杨彦章; 王慧
Original assignee: Shanghai Advanced Research Institute of CAS
Current assignee: Shanghai Advanced Research Institute of CAS
Priority date: 2016-09-27
Filing date: 2016-09-27
Publication date: 2021-03-26
Anticipated expiration: 2036-09-27
Also published as: CN107866250A

Abstract

The invention provides a preparation method of a carbon-coated noble metal nano catalyst, which at least comprises the following steps: 1) preparation of Co₂C, a catalyst; 2) mixing the Co₂Placing the C catalyst in a high-temperature reaction furnace and introducing inert gasCalcining, and taking out the calcined Co2C catalyst after a certain time; 3) providing a soluble noble metal salt solution, calcining the Co₂And C, adding the catalyst into the soluble noble metal salt solution, soaking for a plurality of hours at a certain temperature, washing, filtering and drying to obtain the carbon-coated noble metal nano catalyst. The preparation method has the advantages of mild conditions, low cost, simple process, low energy consumption and high yield, and can obtain various carbon-coated noble metal nano catalysts.

Description

Preparation method of carbon-coated noble metal nano catalyst

Technical Field

The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of a carbon-coated noble metal nano catalyst.

Background

The noble metal refers to gold, silver and platinum group (platinum, osmium, iridium, ruthenium, rhodium and palladium) elements, and has important strategic position in development at present, and particularly, the platinum group metal is regarded as the 'present industrial vitamin' in the middle of the 20 th century. Due to large specific surface area, high surface energy, high surface activity and high stability, the material is widely applied to the fields of catalysts, vessel devices, information sensing materials, high-technology materials (electrical contact materials, brazing filler metals, wrapping materials, electroplating, composite materials and sizing agents), energy materials, medical and environment-friendly materials and the like. 85% of the requirements for production, purification, oxidation, dehydrogenation, isomerization, synthesis, etc. in the chemical and petroleum industries depend on catalysts, more than half of which are noble metal-containing catalysts. Although the noble metal is widely used, it is expensive and a bottleneck in wide use, and thus it is necessary to stabilize the noble metal to improve the utilization of the noble metal.

The carbon-coated noble metal is a composite material with a nanocapsule structure, which is formed by taking noble metal nanoparticles as cores and coating concentric carbon structure layers outside the noble metal nanoparticles. The material with the structure not only shows a nanometer size effect, but also overcomes the defects of thermal instability, chemical instability and the like of the nanometer metal material due to overlarge surface energy, so that the carbon-coated noble metal material has good thermal stability and can improve the dispersity of the noble metal nanometer catalyst. Therefore, it is important to develop a method for preparing carbon-coated noble metal with mild conditions and simple operation.

Disclosure of Invention

In view of the above disadvantages of the prior art, the present invention is directed to a method for preparing a carbon-coated noble metal nanocatalyst, which is used to solve the problems of large equipment load, high energy consumption, high cost, low yield, etc. in the prior art for preparing a carbon-coated noble metal nanocatalyst.

In order to achieve the above and other related objects, the present invention provides a method for preparing a carbon-coated noble metal nanocatalyst, the method at least comprising:

1) preparation of Co₂C, a catalyst;

2) mixing the Co₂Placing the catalyst C in a high-temperature reaction furnace, introducing inert gas for calcination, and after a certain time, calcining the Co₂C, taking out the catalyst;

3) providing a soluble noble metal salt solution, calcining the Co₂And C, adding the catalyst into the soluble noble metal salt solution, soaking for a plurality of hours at a certain temperature, washing, filtering and drying to obtain the carbon-coated noble metal nano catalyst.

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 1), the Co is prepared₂The catalyst C comprises the following steps:

1-1) preparation of Co by precipitation or impregnation₃O₄；

1-2) reacting said Co₃O₄Placing the mixture in a reaction device, and introducing H into the reaction device at a certain temperature₂And inert gas for a certain time;

1-3) introducing mixed gas of carbon monoxide and inert gas or mixed gas of synthesis gas and inert gas into the reaction device at a certain temperature for a certain time to obtain the Co₂And C, a catalyst.

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 1-1), the Co prepared by adopting an impregnation method₃O₄Comprises a carrier, and adopts an impregnation method to prepare the Co₃O₄The method comprises the following steps:

1-1-1) according to Co₃O₄In an amount to provide a quantity of carrier;

1-1-2) according to Co₃O₄The loading amount and the composition ratio of the carrier are that the salt of all metal components except the alkali metal is configured into a uniform mixed salt solution with the same volume as the carrier;

1-1-3) adding the mixed salt solution into the carrier in a manner of dripping while stirring at a certain temperature;

1-1-4) after the titration is finished, keeping the temperature unchanged and dipping;

1-1-5) drying and roasting the dipped solution to obtain the Co₃O₄。

As a preferable embodiment of the method for preparing the carbon-coated noble metal nano catalyst of the present invention, in the step 1-1-1), the support includes ZrO₂、TiO₂、SiO₂、Al₂O₃Or one or more of activated carbon.

As a preferable embodiment of the method for preparing the carbon-coated noble metal nano catalyst of the present invention, in the step 1-1-2), the salts of all metal components except for the alkali metal include a main metal cobalt salt, and the main metal cobalt salt includes one or more of chloride, nitrate, sulfate, carbonate, or acetate; the total molar concentration of the metal salt in the mixed salt solution is 0.01-5 mol/L.

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 1-1-4), the dipping temperature is 10-70 ℃, and the dipping time is 1-48 h.

As a preferred scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 1-1-5), the drying temperature is 20-200 ℃, and the drying time is 2-100 h; the roasting temperature is 200-600 ℃, and the roasting time is 0.5-24 h.

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 1-1), the Co is prepared by adopting a precipitation method₃O₄The method comprises the following steps:

1-1-1) according to Co₃O₄Preparing salt of all metal components except the alkali metal into a uniformly mixed salt solution, and preparing a precipitator solution;

1-1-2) providing mother liquor, and dripping the mixed salt solution and the precipitant solution into the mother liquor in a cocurrent manner at a certain temperature for precipitation;

1-1-3) after titration, keeping the temperature unchanged and aging;

1-1-4) separating, washing, drying and roasting the aged titration solution to obtain the Co₃O₄。

As a preferable embodiment of the method for preparing the carbon-coated noble metal nano catalyst of the present invention, in step 1-1-1), the salts of all metal components except for the alkali metal include a main metal cobalt salt, and the main metal cobalt salt includes one or more of chloride, nitrate, sulfate, carbonate, or acetate; the total molar concentration of the metal salt in the mixed salt solution is 0.01-5 mol/L.

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst of the present invention, in step 1-1-1), the precipitant in the precipitant solution includes one or more of potassium hydroxide, sodium carbonate, ammonium carbonate and sodium bicarbonate, and the molar concentration of the precipitant in the precipitant solution is 0.01mol/L to 5 mol/L.

As a preferable embodiment of the method for preparing the carbon-coated noble metal nano catalyst of the present invention, the Co is₃O₄The method comprises a carrier, and in the step 1-1-2), before the mixed salt solution and the precipitant solution are dripped into the mother liquor in a cocurrent mode at a certain temperature, the method also comprises a step of adding the carrier into the mother liquor.

As a preferable embodiment of the method for preparing the carbon-coated noble metal nano catalyst of the present invention, the support comprises ZrO₂、TiO₂、SiO₂、Al₂O₃Or one or more of activated carbon.

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 1-1-2), the volume ratio of the precipitant solution and the mixed salt solution dropped into the mother liquor is 1: 5-5: 1; the precipitation temperature is 10-100 ℃; the pH of the precipitate is 5-14.

As a preferred scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 1-1-4), the drying temperature is 20-200 ℃, and the drying time is 2-100 h; the roasting temperature is 200-600 ℃, and the roasting time is 0.5-24 h.

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 1-2), H is introduced into the reaction device₂The temperature of the mixed gas with inert gas is 150-500 ℃, and H₂And H in a mixed gas of an inert gas₂The volume percentage of (A) is 5-100%; introducing H into the reaction device₂The time of the mixed gas of the inert gas and the inert gas is 0 to 48 hours.

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 1-3), the temperature of the mixed gas of carbon monoxide and inert gas or the mixed gas of synthesis gas and inert gas introduced into the reaction device is 150-400 ℃ in the step of introducing the mixed gas of carbon monoxide and inert gas into the reaction device, and the volume percentage of the carbon monoxide or the synthesis gas in the mixed gas is 5-100%; and introducing the mixed gas of carbon monoxide and inert gas or the mixed gas of synthesis gas and inert gas into the reaction device for 0.5-48 h.

As a preferable embodiment of the preparation method of the carbon-coated noble metal nano catalyst of the present invention, in the step 2), the inert gas is one or more of nitrogen, argon or helium, the purity of the inert gas is greater than or equal to 99.99%, and the space velocity is 100mlg^-1h^-1～20000mlg^-1h^-1。

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 2), the calcining temperature is 200-800 ℃, and the calcining time is 3-24 h.

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 3), the soluble noble metal salt solution comprises one or more of iridium nitrate, silver nitrate, rhodium nitrate, palladium nitrate, chloroplatinic acid, platinum nitrate, silver nitrate or chloroauric acid, and the molar concentration of the soluble noble metal salt solution is 0.01mol/L to 5 mol/L.

As a preferred scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 3), the soaking temperature is 20-80 ℃, and the soaking time is 0.5-5 h.

As a preferable scheme of the preparation method of the carbon-coated noble metal nano catalyst, in the step 3), the drying temperature is 20-200 ℃, and the drying time is 2-50 h.

As described above, the preparation method of the carbon-coated noble metal nano catalyst of the present invention has the following beneficial effects: the preparation method of the carbon-coated noble metal nano catalyst at least comprises the following steps: 1) preparation of Co₂C, a catalyst; 2) mixing the Co₂Placing the catalyst C in a high-temperature reaction furnace, introducing inert gas for calcination, and taking out the calcined Co2C catalyst after a certain time; 3) providing a soluble noble metal salt solution, calcining the Co₂Adding a catalyst C into the soluble noble metal salt solution, soaking for a plurality of hours at a certain temperature, washing, filtering and drying to obtain the carbon-coated noble metal nanoA catalyst. The preparation method has the advantages of mild conditions, low cost, simple process, low energy consumption and high yield, and can obtain various carbon-coated noble metal nano catalysts.

Drawings

Fig. 1 shows a flow chart of a preparation method of the carbon-coated noble metal nano-catalyst of the invention.

Fig. 2 shows a raman spectrum of a carbon-coated platinum metal nanoparticle prepared by the method for preparing a carbon-coated noble metal nanocatalyst provided in example 1 of the present invention.

Fig. 3 shows a transmission electron microscope image of carbon-coated platinum metal nanoparticles prepared by the method for preparing a carbon-coated noble metal nanocatalyst provided in example 1 of the present invention.

Fig. 4 shows an X-ray diffraction pattern of carbon-coated platinum metal nanoparticles prepared for the method of preparing a carbon-coated noble metal nanocatalyst provided in example 1 of the present invention.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Please refer to fig. 1 to 4. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and although the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation, the type, quantity and proportion of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.

Referring to fig. 1, the present invention provides a method for preparing a carbon-coated noble metal nano-catalyst, which at least includes:

1) preparation of Co₂C, a catalyst;

In step 1), please refer to step S1 in FIG. 1, preparing Co₂And C, a catalyst.

As an example, the Co was prepared₂The catalyst C comprises the following steps:

1-1) preparation of Co by precipitation or impregnation₃O₄；

As an example, in step 1-1), the Co may be prepared by a precipitation method or an impregnation method₃O₄。

In one example, the Co is prepared by an impregnation method₃O₄Comprises a carrier, and adopts an impregnation method to prepare the Co₃O₄The method comprises the following steps:

1-1-1) according to Co₃O₄In an amount to provide a quantity of carrier;

1-1-5) drying and roasting the dipped solution to obtain the Co₃O₄。

As an example, the support comprises ZrO₂、TiO₂、SiO₂、Al₂O₃Or one or more of activated carbon.

As an example, in step 1-1-2) of the impregnation method, the salts of all the metal components except the alkali metal include a main metal cobalt salt including one or more of chloride, nitrate, sulfate, carbonate, or acetate; the total molar concentration of the metal salts in the mixed salt solution is 0.01-5 mol/L, and preferably the total molar concentration of the metal salts in the mixed salt solution is 1-3 mol/L.

As an example, in step 1-1-4) of the impregnation method, the impregnation temperature is 10 ℃ to 70 ℃, preferably, the impregnation temperature is 20 ℃ to 40 ℃; the dipping time is 1 h-48 h, preferably, the dipping time is 5 h-12 h.

As an example, in the step 1-1-5) of the impregnation method, the drying temperature is 20 ℃ to 200 ℃ and the drying time is 2h to 100 h; preferably, the drying temperature is 40-120 ℃, and the drying time is 4-60 h; the roasting temperature is 200-600 ℃, and the roasting time is 0.5-24 h; preferably, the roasting temperature is 250-500 ℃, and the roasting time is 2-10 h.

As an example, the drying process in steps 1-1-5) of the impregnation method may be performed under vacuum conditions, an air atmosphere, and an inert atmosphere, and preferably, the drying process is performed under an air atmosphere.

In another example, the Co is prepared by precipitation₃O₄The method comprises the following steps:

1-1-3) after titration, keeping the temperature unchanged and aging;

As an example, in step 1-1-1) of the precipitation method, the salts of all metal components except the alkali metal include a main metal cobalt salt including one or more of chloride, nitrate, sulfate, carbonate, or acetate; the total molar concentration of the metal salts in the mixed salt solution is 0.01-5 mol/L, and preferably the total molar concentration of the metal salts in the mixed salt solution is 1-3 mol/L.

As an example, in step 1-1-1) of the precipitation method, the precipitant in the precipitant solution includes one or more of potassium hydroxide, sodium carbonate, ammonium carbonate, and sodium bicarbonate, and the molar concentration of the precipitant in the precipitant solution is 0.01mol/L to 5mol/L, and preferably, the molar concentration of the precipitant in the precipitant solution is 1mol/L to 3 mol/L.

As an example, the Co₃O₄The method comprises a carrier, and in the step 1-1-2) of the precipitation method, before dropping the mixed salt solution and the precipitant solution into the mother liquor in a cocurrent manner at a certain temperature, the method also comprises a step of adding the carrier into the mother liquor. The carrier comprises ZrO₂、TiO₂、SiO₂、Al₂O₃Or one or more of activated carbon.

As an example, in step 1-1-2) of the precipitation method, the volume ratio of the precipitant solution to the mixed salt solution dropped into the mother liquor is 1:5 to 5: 1; the precipitation temperature is 10-100 ℃, preferably, the precipitation temperature is 20-80 ℃; the precipitation pH is 5-14, preferably, the precipitation pH is 7-11.

As an example, in the step 1-1-4) of the precipitation method, the drying temperature is 20 ℃ to 200 ℃, and the drying time is 2h to 100 h; preferably, the drying temperature is 40-120 ℃, and the drying time is 4-60 h; the roasting temperature is 200-600 ℃, and the roasting time is 0.5-24 h; preferably, the roasting temperature is 250-500 ℃, and the roasting time is 2-10 h.

As an example, the drying process in steps 1-1-4) in the precipitation method may be performed under vacuum conditions, an air atmosphere, and an inert atmosphere, preferably, the drying process is performed under an air atmosphere; the calcination process in steps 1-1-4) in the precipitation method may be performed in a vacuum condition, an air atmosphere, a nitrogen atmosphere, or a helium atmosphere, and preferably, the calcination process is performed in a nitrogen atmosphere and an air atmosphere.

As an example, in the step 1-2), H is introduced into the reaction apparatus₂The temperature of the mixed gas with inert gas is 150-500 ℃, and H₂And H in a mixed gas of an inert gas₂The volume percentage of (A) is 5-100%; introducing H into the reaction device₂The time of the mixed gas with the inert gas is 0 to 48 hours; preferably, H is introduced into the reaction device₂The temperature of the mixed gas with inert gas is 250-350 ℃, H₂And H in a mixed gas of an inert gas₂The volume percentage of (A) is 10-100%; introducing H into the reaction device₂The time of the mixed gas of the inert gas and the inert gas is 0 to 10 hours.

As an example, in the step 1-3), when the mixed gas of carbon monoxide and inert gas or the mixed gas of synthesis gas and inert gas is introduced into the reaction device, the temperature is 150 ℃ to 400 ℃, and the volume percentage of the carbon monoxide or the synthesis gas in the mixed gas is 5% to 100%; the time for introducing the mixed gas of carbon monoxide and inert gas or the mixed gas of synthesis gas and inert gas into the reaction device is 0.5 to 48 hours; preferably, the temperature of the mixed gas of carbon monoxide and inert gas or the mixed gas of synthesis gas and inert gas introduced into the reaction device is 180-250 ℃ when the mixed gas of carbon monoxide and inert gas or the mixed gas of synthesis gas and inert gas is introduced into the reaction device, and the volume percentage of the carbon monoxide or the synthesis gas in the mixed gas is 10-100%; and introducing the mixed gas of carbon monoxide and inert gas or the mixed gas of synthesis gas and inert gas into the reaction device for 5-10 hours.

In step 2), please refer to step S2 in fig. 1, the Co is mixed₂Placing the catalyst C in a high-temperature reaction furnace, introducing inert gas for calcination, and after a certain time, calcining the Co₂And C, taking out the catalyst.

Illustratively, the inert gas is one or more of nitrogen, argon or helium, the purity of the inert gas is greater than or equal to 99.99%, and the space velocity is 100mlg^-1h^-1～20000mlg^-1h^-1Preferably, the space velocity is 1000mlg^-1h^-1～10000mlg^-1h^-1。

As an example, the calcination temperature is 200 ℃ to 800 ℃, preferably, the calcination temperature is 300 ℃ to 450 ℃; the calcination time is 3-24 h, preferably 5-10 h.

In step 3), please refer to step S3 in FIG. 1, a soluble noble metal salt solution is provided, and the Co after calcination is added₂And C, adding the catalyst into the soluble noble metal salt solution, soaking for a plurality of hours at a certain temperature, washing, filtering and drying to obtain the carbon-coated noble metal nano catalyst.

By way of example, the soluble precious metal salt solution comprises one or more of iridium nitrate, silver nitrate, rhodium nitrate, palladium nitrate, chloroplatinic acid, platinum nitrate, silver nitrate or chloroauric acid, and the molar concentration of the soluble precious metal salt solution is 0.01mol/L to 5mol/L, preferably 0.5mol/L to 3 mol/L.

As an example, the soaking temperature is 20 ℃ to 80 ℃, preferably, the soaking temperature is 20 ℃ to 30 ℃; the soaking time is 0.5 h-5 h, preferably 0.5 h-2 h.

By way of example, the drying temperature is 20 ℃ to 200 ℃, preferably 60 ℃ to 120 ℃; the drying time is 2-50 h, preferably 4-10 h.

The following specific examples are illustrative of Co-based compositions of the present invention₂And C, a method for preparing the graphitized hollow nano structure is introduced in detail.

Example 1

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 65 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing for 5H at 400 ℃, then cooling to 220 ℃, switching gas to H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of Fischer-Tropsch reaction, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 400 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the carbon-coated platinum metal nanoparticles. As can be seen from fig. 2 to 4, the carbon-coated platinum metal nanoparticles prepared in this example only contain platinum simple substance and have no residual cobalt, a raman spectrum of the carbon-coated platinum metal nanoparticles is shown in fig. 2, a transmission electron microscope image is shown in fig. 3, and an X-ray diffraction pattern is shown in fig. 4.

Example 2

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 25 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 25 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing for 5H at 400 ℃, then cooling to 220 ℃, switching gas to H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 400 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the carbon-coated platinum metal nanoparticles.

Example 3

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 45 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at the temperature of 45 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is transferred to a muffle furnace to be heated to 330 ℃ by a program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing for 5H at 400 ℃, then cooling to 220 ℃, switching gas to H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 400 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the carbon-coated platinum metal nanoparticles.

Example 4

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 65 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L aluminum platinic acid, stirring at room temperature for 1h, washing, and filteringFiltering, and drying in a drying oven at 100 ℃ for 5h to obtain the carbon-coated platinum metal nanoparticles.

Example 5

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 65 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L silver nitrate solution, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the carbon-coated platinum metal nanoparticles.

Example 6

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 65 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L silver nitrate solution, stirring and stirring at 40 ℃ for 0.5h, washing, filtering, and drying in a 100 ℃ drying oven for 5h to obtain the carbon-coated silver metal nanoparticles.

Example 7

C is to beo(NO₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 65 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 15mL of 2mol/L silver nitrate solution, stirring and stirring at 30 ℃ for 0.5h, washing, filtering, and drying in a 100 ℃ drying oven for 5h to obtain the carbon-coated silver metal nanoparticles.

Example 8

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 25 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 25 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing for 5H at 400 ℃, then cooling to 220 ℃, switching gas to H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 400 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L silver nitrate solution, stirring and soaking at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the carbon-coated silver metal nanoparticles.

Example 9

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 25 ℃ and a pH of 8. Dripping deviceAfter the determination is finished, the mixture is aged for 2h at 25 ℃, is dried for 12h in a 100 ℃ oven after being centrifuged and washed for 6 times, and is transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 h. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing for 5H at 400 ℃, then cooling to 220 ℃, switching gas to H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 400 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L silver nitrate solution, stirring and soaking at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the carbon-coated silver metal nanoparticles.

Example 10

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 45 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at the temperature of 45 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is transferred to a muffle furnace to be heated to 330 ℃ by a program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing for 5H at 400 ℃, then cooling to 220 ℃, switching gas to H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 400 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L silver nitrate solution, stirring and stirring at 30 ℃ for 0.5h, washing, filtering, and drying in a 100 ℃ drying oven for 5h to obtain the carbon-coated silver metal nanoparticles.

Example 11

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 65 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. Taking 1.5g to roastThe catalyst (2) was placed in a reaction tube and 10% H was introduced₂Reducing for 5H at 400 ℃, then cooling to 220 ℃, switching gas to H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 400 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L palladium nitrate solution, stirring and stirring at 30 ℃ for 0.5h, washing, filtering, and drying in a 100 ℃ drying oven for 5h to obtain the carbon-coated palladium metal nanoparticles.

Example 12

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 65 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing at 300 deg.C for 5H, cooling to 220 deg.C, and switching gas to H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L palladium nitrate solution, stirring and stirring at 30 ℃ for 0.5h, washing, filtering, and drying in a 100 ℃ drying oven for 5h to obtain the carbon-coated palladium metal nanoparticles.

Example 13

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 65 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L rhodium nitrate solution, stirring and stirring at 30 ℃ for 0.5h, washing, filtering, and drying in a 100 ℃ drying oven for 5h to obtain the carbon-coated rhodium metal nanoparticles.

Example 14

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃All are prepared into a solution with the concentration of 2 mol/L. Adding mother liquor into a beaker, and adding a certain amount of SiO into the mother liquor₂The two solutions were co-precipitated in a stirred mother liquor in a cocurrent manner by adjusting the cobalt loading to 10%, the titration temperature to 65 ℃ and controlling the titration pH to-8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of calcined 10% Co/SiO₂The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the SiO supported catalyst₂The carbon-coated platinum metal nanoparticles above.

Example 15

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃All are prepared into a solution with the concentration of 2 mol/L. Adding mother liquor into a beaker, and adding a certain amount of SiO into the mother liquor₂The two solutions were co-precipitated in a stirred mother liquor in a cocurrent manner by adjusting the cobalt loading to 20%, the titration temperature to 65 ℃ and controlling the titration pH to-8. Aging at 65 deg.C for 2 hr after titration, centrifuging, washing for 6 times, oven drying at 100 deg.C for 12 hr, and dryingThen transferring the mixture to a muffle furnace to be heated to 330 ℃ in a programmed way and roasted for 3 h. 1.5g of calcined 10% Co/SiO₂The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the SiO supported catalyst₂The carbon-coated platinum metal nanoparticles above.

Example 16

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃All are prepared into a solution with the concentration of 2 mol/L. Adding mother liquor into a beaker, and adding a certain amount of TiO into the mother liquor₂The two solutions were co-precipitated in a stirred mother liquor in a cocurrent manner by adjusting the cobalt loading to 10%, the titration temperature to 65 ℃ and controlling the titration pH to-8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of calcined 10% Co/TiO was taken₂The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the supported TiO₂The carbon-coated platinum metal nanoparticles above.

Example 17

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃All are prepared into a solution with the concentration of 2 mol/L. Adding mother liquor into a beaker, adding the mother liquorAdding a certain amount of TiO₂The two solutions were co-precipitated in a stirred mother liquor in a cocurrent manner by adjusting the cobalt loading to 10%, the titration temperature to 65 ℃ and controlling the titration pH to-8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of calcined 10% Co/TiO was taken₂The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L silver nitrate solution, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the supported TiO₂The carbon-coated silver metal nanoparticles above.

Example 18

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃All are prepared into a solution with the concentration of 2 mol/L. Adding mother liquor into a beaker, and adding a certain amount of Al into the mother liquor₂O₃The two solutions were co-precipitated in a stirred mother liquor in a cocurrent manner by adjusting the cobalt loading to 10%, the titration temperature to 65 ℃ and controlling the titration pH to-8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of calcined 10% Co/Al are taken₂O₃The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid solution, stirring at room temperature for 1h, washing, filtering, and then putting into a 100 ℃ oven to be driedDrying for 5h to obtain the loaded Al₂O₃The carbon-coated platinum metal nanoparticles above.

Example 19

Mixing Co (NO)₃)₂·6H₂O and Na₂CO₃All are prepared into a solution with the concentration of 2 mol/L. Adding mother liquor into a beaker, and adding a certain amount of Al into the mother liquor₂O₃The two solutions were co-precipitated in a stirred mother liquor in a cocurrent manner by adjusting the cobalt loading to 10%, the titration temperature to 65 ℃ and controlling the titration pH to-8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of calcined 10% Co/Al are taken₂O₃The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing the mixture for 5 hours at 350 ℃, then cooling the mixture to 220 ℃, and switching the gas into H₂2/CO-synthesis gas at a space velocity of 2000mlg^-1h^-1. He is introduced after 10h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L rhodium nitrate solution, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the Al-loaded catalyst₂O₃The carbon-coated rhodium metal nanoparticles above.

Example 20

Weighing 10g of SiO₂Placing into a beaker according to SiO₂So that the cobalt loading was 10%, the amount of Co (NO) was determined₃)₂·6H₂O is prepared into 10gSiO with the concentration of 2mol/L and the volume of₂Water-absorbing capacity of the solution. The above solution was added dropwise to the carrier at 25 ℃ with stirring. After titration, the mixture is soaked for 12 hours at 25 ℃, then is placed in a 100 ℃ oven for drying for 12 hours, and then is transferred to a muffle furnace for roasting for 3 hours by temperature programming to 330 ℃. 1.5g of calcined 10% Co/SiO₂The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing for 5h at 400 ℃, then cooling to 220 ℃, switching the gas to pure CO, and controlling the space velocity to 2000mlg^-1h^-1. After being treated for 20h, the mixture is led toHe, space velocity 8000mlg^-1h^-1Raising the temperature to 400 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the SiO supported catalyst₂The carbon-coated platinum metal nanoparticles above.

Example 21

Weighing 10g of SiO₂Placing into a beaker according to SiO₂So that the cobalt loading was 20%, the amount of Co (NO) was determined₃)₂·6H₂O is prepared into 10gSiO with the concentration of 2mol/L and the volume of₂Water-absorbing capacity of the solution. The above solution was added dropwise to the carrier at 25 ℃ with stirring. After titration, the mixture is soaked for 12 hours at 25 ℃, then is placed in a 100 ℃ oven for drying for 12 hours, and then is transferred to a muffle furnace for roasting for 3 hours by temperature programming to 330 ℃. 1.5g of calcined 20% Co/SiO₂The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing for 5h at 350 ℃, then cooling to 220 ℃, switching the gas to pure CO, and controlling the space velocity to 2000mlg^-1h^-1. He is introduced after 20h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the SiO supported catalyst₂The carbon-coated platinum metal nanoparticles above.

Example 22

Weighing 10g of SiO₂Placing into a beaker according to SiO₂So that the cobalt loading was 20%, the amount of Co (NO) was determined₃)₂·6H₂O is prepared into 10gSiO with the concentration of 2mol/L and the volume of₂Water-absorbing capacity of the solution. The above solution was added dropwise to the carrier at 25 ℃ with stirring. After titration, the mixture is soaked for 12 hours at 25 ℃, then is placed in a 100 ℃ oven for drying for 12 hours, and then is transferred to a muffle furnace for roasting for 3 hours by temperature programming to 330 ℃. 1.5g of calcined 20% Co/SiO₂The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing for 5h at 350 ℃, then cooling to 220 ℃, switching the gas to pure CO, and controlling the space velocity to 2000mlg^-1h^-1. He is introduced after 20h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L silver nitrate solution, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the SiO supported catalyst₂The carbon-coated silver metal nanoparticles above.

Example 23

Weighing 10g of SiO₂Placing into a beaker according to SiO₂So that the cobalt loading was 20%, the amount of Co (NO) was determined₃)₂·6H₂O is prepared into 10gSiO with the concentration of 2mol/L and the volume of₂Water-absorbing capacity of the solution. The above solution was added dropwise to the carrier at 25 ℃ with stirring. After titration, the mixture is soaked for 12 hours at 25 ℃, then is placed in a 100 ℃ oven for drying for 12 hours, and then is transferred to a muffle furnace for roasting for 3 hours by temperature programming to 330 ℃. 1.5g of calcined 20% Co/SiO₂The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing for 5h at 350 ℃, then cooling to 220 ℃, switching the gas to pure CO, and controlling the space velocity to 2000mlg^-1h^-1. He is introduced after 20h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L palladium nitrate solution, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the SiO supported catalyst₂The carbon-coated palladium metal nanoparticles.

Example 24

Weighing 10g of TiO₂Placing into a beaker according to TiO₂So that the cobalt loading was 20%, the amount of Co (NO) was determined₃)₂·6H₂O is prepared into 10g TiO with the concentration of 2mol/L₂Water-absorbing capacity of the solution. The above solution was added dropwise to the carrier at 25 ℃ with stirring. Soaking at 25 deg.C for 12h after titration, oven drying at 100 deg.C for 12h, and dryingTransferring the mixture into a muffle furnace, and carrying out roasting for 3 hours by temperature programming to 330 ℃. 1.5g of calcined 20% Co/TiO was taken₂The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing for 5h at 350 ℃, then cooling to 220 ℃, switching the gas to pure CO, and controlling the space velocity to 2000mlg^-1h^-1. He is introduced after 20h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L palladium nitrate solution, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the supported TiO₂The carbon-coated palladium metal nanoparticles.

Example 25

Weighing 10g of TiO₂Placing into a beaker according to TiO₂So that the cobalt loading was 20%, the amount of Co (NO) was determined₃)₂·6H₂O is prepared into 10g TiO with the concentration of 2mol/L₂Water-absorbing capacity of the solution. The above solution was added dropwise to the carrier at 25 ℃ with stirring. After titration, the mixture is soaked for 12 hours at 25 ℃, then is placed in a 100 ℃ oven for drying for 12 hours, and then is transferred to a muffle furnace for roasting for 3 hours by temperature programming to 330 ℃. 1.5g of calcined 20% Co/TiO was taken₂The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing for 5h at 350 ℃, then cooling to 220 ℃, switching the gas to pure CO, and controlling the space velocity to 2000mlg^-1h^-1. He is introduced after 20h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid solution, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the supported TiO₂The carbon-coated platinum metal nanoparticles above.

Example 26

Weighing 10g of Al₂O₃Placing into a beaker according to TiO₂So that the cobalt loading was 20%, the amount of Co (NO) was determined₃)₂·6H₂O is prepared into 10g of Al with the concentration of 2mol/L and the volume₂O₃Of water absorption capacityAnd (3) solution. The above solution was added dropwise to the carrier at 25 ℃ with stirring. After titration, the mixture is soaked for 12 hours at 25 ℃, then is placed in a 100 ℃ oven for drying for 12 hours, and then is transferred to a muffle furnace for roasting for 3 hours by temperature programming to 330 ℃. 1.5g of calcined 20% Co/Al are taken₂O₃The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing for 5h at 350 ℃, then cooling to 220 ℃, switching the gas to pure CO, and controlling the space velocity to 2000mlg^-1h^-1. He is introduced after 20h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid solution, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the Al-loaded catalyst₂O₃The carbon-coated platinum metal nanoparticles above.

Example 27

Weighing 10g of Al₂O₃Placing into a beaker according to TiO₂So that the cobalt loading was 20%, the amount of Co (NO) was determined₃)₂·6H₂O is prepared into 10g of Al with the concentration of 2mol/L and the volume₂O₃Water-absorbing capacity of the solution. The above solution was added dropwise to the carrier at 25 ℃ with stirring. After titration, the mixture is soaked for 12 hours at 25 ℃, then is placed in a 100 ℃ oven for drying for 12 hours, and then is transferred to a muffle furnace for roasting for 3 hours by temperature programming to 330 ℃. 1.5g of calcined 20% Co/Al are taken₂O₃The catalyst was loaded into a reaction tube and 10% H was introduced₂Reducing for 5h at 350 ℃, then cooling to 220 ℃, switching the gas to pure CO, and controlling the space velocity to 2000mlg^-1h^-1. He is introduced after 20h of treatment, and the space velocity is 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 10 hours, and then cooling and taking out. Putting the taken catalyst into a beaker, adding 20mL of 1mol/L chloroplatinic acid solution, stirring and stirring at 40 ℃ for 0.5h, washing, filtering, and drying in a 100 ℃ drying oven for 5h to obtain the Al-loaded catalyst₂O₃The carbon-coated platinum metal nanoparticles above.

Example 28

Mixing Co (N)O₃)₂·6H₂O and Na₂CO₃A solution having a concentration of 2mol/L was prepared, and titration was carried out at a temperature of 65 ℃ and a pH of 8. After titration, the mixture is aged for 2 hours at 65 ℃, is dried for 12 hours in a 100 ℃ oven after being centrifuged and washed for 6 times, and is then transferred to a muffle furnace to be heated to 330 ℃ by program and roasted for 3 hours. 1.5g of the calcined catalyst was placed in a reaction tube and H was introduced₂Treating the synthesis gas with/CO 2 at 250 deg.C for 20h, introducing He, and setting the space velocity at 8000mlg^-1h^-1Raising the temperature to 350 ℃, maintaining the temperature for 15h, and then cooling and taking out. And putting the taken catalyst into a beaker, adding 20mL of 1mol/L silver nitrate solution, stirring at room temperature for 1h, washing, filtering, and drying in an oven at 100 ℃ for 5h to obtain the carbon-coated platinum metal nanoparticles.

In summary, the present invention provides a method for preparing a carbon-coated noble metal nano-catalyst, which at least comprises: 1) preparation of Co₂C, a catalyst; 2) mixing the Co₂Placing the catalyst C in a high-temperature reaction furnace, introducing inert gas for calcination, and taking out the calcined Co2C catalyst after a certain time; 3) providing a soluble noble metal salt solution, calcining the Co₂And C, adding the catalyst into the soluble noble metal salt solution, soaking for a plurality of hours at a certain temperature, washing, filtering and drying to obtain the carbon-coated noble metal nano catalyst. The preparation method has the advantages of mild conditions, low cost, simple process, low energy consumption and high yield, and can obtain various carbon-coated noble metal nano catalysts.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A preparation method of a carbon-coated noble metal nano catalyst is characterized by at least comprising the following steps:

1) preparation of Co₂C catalyst, preparation of said Co₂The catalyst C comprises the following steps: 1-1) preparation of Co by precipitation or impregnation₃O₄(ii) a 1-2) reacting said Co₃O₄Placing the mixture in a reaction device, and introducing H into the reaction device at a certain temperature₂And inert gas for a certain time; 1-3) introducing mixed gas of carbon monoxide and inert gas or mixed gas of synthesis gas and inert gas into the reaction device at a certain temperature for a certain time to obtain the Co₂C, a catalyst, wherein the temperature in the step 1-3) is 150-400 ℃, and the volume percentage of carbon monoxide or synthesis gas in the mixed gas is 5-100%; the time for introducing the mixed gas of carbon monoxide and inert gas or the mixed gas of synthesis gas and inert gas into the reaction device is 0.5 to 48 hours;

2) mixing the Co₂Placing the catalyst C in a high-temperature reaction furnace, introducing inert gas for calcination, and after a certain time, calcining the Co₂C, taking out the catalyst, wherein the inert gas is one or more of nitrogen, argon or helium, the purity of the inert gas is greater than or equal to 99.99%, and the space velocity is 100mlg^-1h^-1～20000mlg^-1h^-1The calcination temperature is 200-800 ℃, and the calcination time is 3-24 h;

2. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 1, wherein: in step 1-1), the Co prepared by an immersion method₃O₄Comprises a carrier, and adopts an impregnation method to prepare the Co₃O₄The method comprises the following steps:

1-1-1) according to Co₃O₄In an amount to provide a quantity of carrier;

1-1-2) according to Co₃O₄The loading amount and the composition ratio of the carrier are that all metal salts of non-alkali metals are configured into a uniform mixed salt solution with the same volume as the carrier;

1-1-5) drying and roasting the dipped solution to obtain the Co₃O₄。

3. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 2, wherein: in step 1-1-1), the support comprises ZrO₂、TiO₂、SiO₂、Al₂O₃Or one or more of activated carbon.

4. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 2, wherein: in the step 1-1-2), all metal salts of non-alkali metals comprise main metal cobalt salts, and the main metal cobalt salts comprise one or more of chloride, nitrate, sulfate, carbonate or acetate; the total molar concentration of the metal salt in the mixed salt solution is 0.01-5 mol/L.

5. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 2, wherein: in the step 1-1-4), the dipping temperature is 10-70 ℃, and the dipping time is 1-48 h.

6. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 2, wherein: in the step 1-1-5), the drying temperature is 20-200 ℃, and the drying time is 2-100 h; the roasting temperature is 200-600 ℃, and the roasting time is 0.5-24 h.

7.The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 1, wherein: in step 1-1), the Co is prepared by a precipitation method₃O₄The method comprises the following steps:

1-1-1) according to Co₃O₄Preparing a main metal cobalt salt into a uniformly mixed salt solution and preparing a precipitator solution;

1-1-3) after titration, keeping the temperature unchanged and aging;

8. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 7, wherein: in the step 1-1-1), the main metal cobalt salt comprises one or more of chloride, nitrate, sulfate, carbonate or acetate; the total molar concentration of the metal salt in the mixed salt solution is 0.01-5 mol/L.

9. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 7, wherein: in the step 1-1-1), the precipitant in the precipitant solution comprises one or more of potassium hydroxide, sodium carbonate, ammonium carbonate and sodium bicarbonate, and the molar concentration of the precipitant in the precipitant solution is 0.01 mol/L-5 mol/L.

10. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 7, wherein: the Co₃O₄The method comprises a carrier, and in the step 1-1-2), before the mixed salt solution and the precipitant solution are dripped into the mother liquor in a cocurrent mode at a certain temperature, the method also comprises a step of adding the carrier into the mother liquor.

11. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 10, wherein: the carrier comprises ZrO₂、TiO₂、SiO₂、Al₂O₃Or one or more of activated carbon.

12. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in any one of claims 7, 10 or 11, wherein: in the step 1-1-2), the volume ratio of the precipitant solution to the mixed salt solution dropped into the mother liquor is 1: 5-5: 1; the precipitation temperature is 10-100 ℃; the pH value of the precipitate is 5-14.

13. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 7, wherein: in the step 1-1-4), the drying temperature is 20-200 ℃, and the drying time is 2-100 h; the roasting temperature is 200-600 ℃, and the roasting time is 0.5-24 h.

14. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 1, wherein: in the step 1-2), H is introduced into the reaction device₂The temperature of the mixed gas with inert gas is 150-500 ℃, and H₂And H in a mixed gas of an inert gas₂The volume percentage of (A) is 5-100%; introducing H into the reaction device₂The time of the mixed gas of the inert gas and the inert gas is 0 to 48 hours.

15. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 1, wherein: in the step 3), the soluble precious metal salt comprises one or more of iridium nitrate, silver nitrate, rhodium nitrate, palladium nitrate, chloroplatinic acid, platinum nitrate, silver nitrate or chloroauric acid, and the molar concentration of the soluble precious metal salt solution is 0.01-5 mol/L.

16. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 1, wherein: in the step 3), the soaking temperature is 20-80 ℃, and the soaking time is 0.5-5 h.

17. The method for preparing a carbon-coated noble metal nanocatalyst as claimed in claim 1, wherein: in the step 3), the drying temperature is 20-200 ℃, and the drying time is 2-50 h.