阅读说明：本技术 多孔炭负载纳米金属氧化物或纳米金属材料的方法 (Method for loading nano metal oxide or nano metal material on porous carbon ) 是由 不公告发明人 于 2020-08-19 设计创作，主要内容包括：本发明公开了一种多孔炭负载纳米金属氧化物或纳米金属材料的方法包括以下步骤：(1)先将生物质原料与氧化铝颗粒进行配比混合并熔融,炭化后得到分散有氧化铝的炭化固体；(2)再将炭化固体在保护性气氛下温度升至1600-1800℃处理20-24 h,冷却至室温后用稀酸溶液将其浸泡40-60 min,洗净并烘干后得到短程有序且多孔的石墨化固体；(3)将石墨化固体浸泡在酚醛树脂和金属盐的混合熔融液中,取出并炭化得到所述多孔炭负载纳米金属氧化物或纳米金属材料。本发明的制备工艺简单省时,材料经济,制备的多孔炭负载纳米金属材料的比表面积均在700 m～(2)/g以上,抗压强度在25 MPa左右,最高可达26.3 MPa,并且可以根据实际需要调节Al-2O-3粒径和浸泡时间来获得特定孔径的多孔炭负载纳米金属/金属氧化物。(The invention discloses a method for loading a nano metal oxide or a nano metal material on porous carbon, which comprises the following steps: (1) firstly, mixing and melting the biomass raw material and the alumina particles in proportion, and carbonizing to obtain a carbonized solid dispersed with alumina; (2) then the temperature of the carbonized solid is raised to 1600-1800 ℃ in protective atmosphere for treatment for 20-24 h, the carbonized solid is soaked in dilute acid solution for 40-60 min after being cooled to room temperature, and the carbonized solid is cleaned and dried to obtain short-range ordered and porous graphitized solid; (3) and soaking the graphitized solid in the mixed molten liquid of the phenolic resin and the metal salt, taking out and carbonizing to obtain the porous carbon loaded nano metal oxide or nano metal material. The preparation process is simple and time-saving, the material is economical, and the specific surface areas of the prepared porous carbon-loaded nano metal material are 700 m 2 More than g, the compressive strength is about 25 MPa and can reach 26.3 MPa at most, and Al can be adjusted according to actual requirements 2 O 3 The particle size and the soaking time are used for obtaining the porous carbon loaded nano metal/metal oxide with specific pore diameter.)

1. A method for loading nano metal oxide or nano metal material on porous carbon is characterized by comprising the following steps: the method comprises the following steps:

(1) mixing a carbon source and alumina particles according to a mass ratio of 0.5: 1, proportioning and mixing, then heating the mixture to 160 ℃, stirring for 20 min at the temperature to completely melt a carbon source, then placing the melt in a protective atmosphere for heat treatment at 200 ℃ for 24 h, and cooling to room temperature to obtain a carbonized solid dispersed with alumina particles;

(2) heating the carbonized solid to 1600 ℃ in protective atmosphere, treating for 20 h, cooling to room temperature, soaking the carbonized solid in a dilute acid solution for 40 min, cleaning and drying to obtain a short-range ordered and porous graphitized solid;

(3) mixing phenolic resin and metal salt according to a mass ratio of 5: 1, mixing and stirring at 180 ℃ for 20 min for melting, immersing the short-range ordered and porous graphitized solid into a molten liquid for 10 min, taking out, and treating at 900 ℃ for 8 h in a protective atmosphere to obtain a porous carbon-supported nano metal oxide material; placing the porous carbon-supported nano metal oxide material in a reducing atmosphere at 600 ℃ for reacting for 3 h to obtain a porous carbon-supported nano metal material;

wherein the carbon source is cellulose; the particle size of the alumina particles is 0.5 μm; the protective atmosphere is helium; the dilute acid solution is dilute sulfuric acid, and the concentration of the dilute acid solution is 0.1 wt%; the metal salt is an aluminum salt; the reducing atmosphere is hydrogen; the cleaning liquid is 30wt% ethanol water solution; the drying temperature is 90 ℃ and the drying time is 30 min; the stirring speed is 200 r/min.

Technical Field

The invention relates to the technical field of nano material preparation, in particular to a method for loading a nano metal oxide or a nano metal material on porous carbon.

Background

The nano material has surface effect, volume effect, size effect, tunnel effect and the like, so the nano material has wide application prospect in various fields. However, the nanoparticles have too high surface energy due to their too small size, and are very easy to agglomerate, so that it is usually necessary to support the nanomaterial on the porous structure to avoid agglomeration. The most typical porous carbon material has high porosity and is a good carrier for loading nano materials. For example, CN201410048253.6 discloses a method for loading nano metal oxide or nano metal material on porous carbon, which can be obtained by directly carbonizing a mixed melt of saccharides and metal salts at high temperature, and has a simple process, but the porous carbon material has poor mechanical properties due to its loose structure with amorphous distribution, and is easily damaged in an environment requiring a certain mechanical force to lose its original properties, and meanwhile, the generation of pores in the porous carbon material obtained by direct carbonization has randomness, so the pore size distribution is wide and is difficult to control. Therefore, the preparation of a porous carbon-supported nanoparticle material with controllable pore diameter and excellent mechanical properties is an urgent need.

Disclosure of Invention

The present invention aims at providing a method for loading nano metal oxide or nano metal material on porous carbon to solve the problems in the background art.

In order to solve the technical problems, the invention provides the following technical scheme: a method for loading nano metal oxide or nano metal material on porous carbon comprises the following steps:

(1) mixing a carbon source and alumina particles according to the mass ratio (0.5-9): 1, proportioning and mixing, then raising the temperature of the mixture to 160-200 ℃, stirring for 20-30 min at the temperature to completely melt the carbon source, then placing the melt in a protective atmosphere for heat treatment at 200-230 ℃ for 24-36 h, and cooling to room temperature to obtain a carbonized solid dispersed with alumina particles;

because the alumina particles have higher melting point and hardness, the alumina particles can be uniformly dispersed in a molten carbon source after being stirred and occupy a certain space, and a foundation is provided for the subsequent acid solution to etch the alumina particles to form a porous structure.

(2) Heating the carbonized solid to 1600-1800 ℃ in protective atmosphere, treating for 20-24 h, cooling to room temperature, soaking the carbonized solid in a dilute acid solution for 40-60 min, cleaning and drying to obtain a short-range ordered porous graphitized solid;

the carbon source can form amorphous carbon in disordered distribution after carbonization, and the amorphous carbon is easy to be reconnected into a planar structure consisting of a large number of six-membered rings under the condition of more than 1500 ℃, namely graphitization. The carbonized solid is subjected to high-temperature treatment under the supporting action of hard granular alumina, so that the collapse of a carbon skeleton can be effectively avoided, and a porous structure is formed; meanwhile, a short-range ordered graphitized network can be formed by processing at 1600-1800 ℃ for 20-24 h, so that the toughness of the carbon atom framework can be greatly improved, and the mechanical property of the carbon atom framework can be enhanced; however, too high a temperature will on the one hand melt the alumina particles and on the other hand form a graphitized structure with long-range order, which leads to a large reduction of the porosity, and therefore the graphitization temperature should be controlled within the preferred range.

As carbon atoms in the graphitized solid have a stable two-dimensional plane structure and are not easy to generate oxidation-reduction reaction, the alumina particles in the invention can be used for removing impurities and can react with residual non-graphitized amorphous carbon to generate aluminum carbide, and the aluminum oxide and the aluminum carbide can be removed by subsequent etching of dilute acid solution, thereby effectively improving the specific surface area of the graphitized solid.

(3) Mixing phenolic resin and metal salt according to the mass ratio of (5-40): 1 mixing and stirring at 180-200 ℃ for 20-40 min for melting, immersing the short-range ordered and porous graphitized solid into the molten liquid for 10-20 min, taking out and treating at 900-1000 ℃ for 8-24 h in a protective atmosphere to obtain a porous carbon-supported nano metal oxide material; and placing the porous carbon-supported nano metal oxide material in a reducing atmosphere at 600-850 ℃ for reaction for 3-8 h to obtain the porous carbon-supported nano metal material.

After carbonization, the phenolic resin can load the generated nano metal/metal oxide on one hand and is connected with carbon atoms in the graphitized solid on the other hand, so that a stable composite structure is formed, namely the porous carbon loaded nano metal/metal oxide material.

Further, the carbon source can be one or more of cellulose, starch, maltose, glucose, acrylic resin, triglyceride and ethyl acetate.

Further, the alumina particles have a particle size of 0.5 to 5 μm.

Since the pores of the graphitized solid are formed by etching alumina particles, the particle size of the alumina particles is indirectly related to the pore size of the final porous carbon-supported nano metal/metal oxide material, and the pore size of the final product can be adjusted by adjusting the particle size of the alumina particles.

Further, the protective atmosphere is one or more of rare gases.

Further, the dilute acid solution is one of dilute sulfuric acid, dilute hydrochloric acid and dilute nitric acid, and the concentration is 0.1-3 wt%.

Further, the metal salt contains one of aluminum, iron, copper, zinc, nickel, silver, gold, vanadium, chromium and manganese.

Further, the reducing atmosphere is hydrogen, carbon monoxide or a mixture of the two.

Further, the cleaning liquid is 30-80wt% ethanol water solution.

Further, the drying temperature is 90-120 ℃, and the drying time is 30-60 min.

Furthermore, the stirring speed is 200-1200 r/min.

Compared with the prior art, the invention has the following beneficial effects:

(1) according to the invention, a carbon source and alumina particles are mixed to form a porous graphitized network structure under the supporting action of alumina, so that the mechanical property of the porous carbon carrier is greatly improved, and the problem of poor obdurability of the porous carbon carrier in the prior art is solved; meanwhile, the alumina particles can remove impurities from the residual amorphous carbon in the graphitized solid, so that the specific surface area of the porous carbon-loaded nano metal/metal oxide material is improved.

(2) The difference between the pore diameter of the porous carbon-loaded nano metal/metal oxide material and the particle diameter of the alumina particles before etching is not large, the difference is approximately in linear relation with the soaking time of the graphitized solid in the mixed molten liquid of the phenolic resin and the metal salt, and the pore diameter of the porous carbon-loaded nano metal/metal oxide material can be adjusted in a large range by adjusting the particle diameter of the alumina particles and the soaking time according to actual needs, so that the pore diameter controllability of the porous carbon carrier is realized.

(3) The materials such as the alumina, the metal salt, the phenolic resin and the like used by the invention have wide sources, are economical and practical, have simple and time-saving preparation process and have wide application prospect.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

The invention provides a method for loading a nano metal oxide or a nano metal material on porous carbon, which comprises the following steps:

(1) mixing a carbon source and alumina particles according to a mass ratio of 0.5: 1, proportioning and mixing, then heating the mixture to 160 ℃, stirring for 20 min at the temperature to completely melt a carbon source, then placing the melt in a protective atmosphere for heat treatment at 200 ℃ for 24 h, and cooling to room temperature to obtain a carbonized solid dispersed with alumina particles;

(2) heating the carbonized solid to 1600 ℃ in protective atmosphere, treating for 20 h, cooling to room temperature, soaking the carbonized solid in a dilute acid solution for 40 min, cleaning and drying to obtain a short-range ordered and porous graphitized solid;

(3) mixing phenolic resin and metal salt according to a mass ratio of 5: 1, mixing and stirring at 180 ℃ for 20 min for melting, immersing the short-range ordered and porous graphitized solid into a molten liquid for 10 min, taking out, and treating at 900 ℃ for 8 h in a protective atmosphere to obtain a porous carbon-supported nano metal oxide material; and placing the porous carbon-supported nano metal oxide material in a reducing atmosphere at 600 ℃ for reacting for 3 h to obtain the porous carbon-supported nano metal material.

Wherein the carbon source is cellulose; the particle size of the alumina particles is 0.5 μm; the protective atmosphere is helium; the dilute acid solution is dilute sulfuric acid, and the concentration of the dilute acid solution is 0.1 wt%; the metal salt is an aluminum salt; the reducing atmosphere is hydrogen; the cleaning liquid is 30wt% ethanol water solution; the drying temperature is 90 ℃ and the drying time is 30 min; the stirring speed is 200 r/min.

Example two

The invention provides a method for loading a nano metal oxide or a nano metal material on porous carbon, which comprises the following steps:

(1) mixing a carbon source and alumina particles according to a mass ratio of 9: 1, proportioning and mixing, then heating the mixture to 200 ℃, stirring for 30 min at the temperature to completely melt a carbon source, then placing the melt in a protective atmosphere for heat treatment at 230 ℃ for 36 h, and cooling to room temperature to obtain a carbonized solid dispersed with alumina particles;

(2) heating the carbonized solid to 1800 ℃ in a protective atmosphere, treating for 24 h, cooling to room temperature, soaking the carbonized solid in a dilute acid solution for 60 min, cleaning and drying to obtain a short-range ordered porous graphitized solid;

(3) mixing phenolic resin and metal salt according to a mass ratio of 40: 1, mixing and stirring at 200 ℃ for 40 min for melting, immersing the short-range ordered and porous graphitized solid into a molten liquid for 20 min, taking out, and treating at 1000 ℃ for 24 h in a protective atmosphere to obtain a porous carbon-supported nano metal oxide material; and placing the porous carbon-supported nano metal oxide material in a reducing atmosphere to react for 8 hours at 850 ℃ to obtain the porous carbon-supported nano metal material.

Wherein the carbon source is cellulose; the particle size of the alumina particles is 5 mu m; the protective atmosphere is helium; the dilute acid solution is dilute sulfuric acid, and the concentration of the dilute acid solution is 3 wt%; the metal salt is an aluminum salt; the reducing atmosphere is hydrogen; the cleaning liquid is 80wt% ethanol water solution; the drying temperature is 120 ℃, and the drying time is 60 min; the stirring speed is 1200 r/min.

EXAMPLE III

The invention provides a method for loading a nano metal oxide or a nano metal material on porous carbon, which comprises the following steps:

(1) mixing a carbon source and alumina particles according to a mass ratio of 3: 1, proportioning and mixing, then heating the mixture to 180 ℃, stirring for 25 min at the temperature to completely melt a carbon source, then placing the melt in a protective atmosphere for heat treatment at 210 ℃ for 30 h, and cooling to room temperature to obtain a carbonized solid dispersed with alumina particles;

(2) heating the carbonized solid to 1700 ℃ in protective atmosphere for treatment for 22 h, cooling to room temperature, soaking the carbonized solid in a dilute acid solution for 50 min, cleaning and drying to obtain a short-range ordered and porous graphitized solid;

(3) mixing phenolic resin and metal salt according to a mass ratio of 10: 1, mixing and stirring at 190 ℃ for 30 min for melting, immersing the short-range ordered and porous graphitized solid into a molten liquid for 16 min, taking out, and treating at 950 ℃ for 20 h in a protective atmosphere to obtain a porous carbon-supported nano metal oxide material; and placing the porous carbon-supported nano metal oxide material in a reducing atmosphere at 800 ℃ for reacting for 6 h to obtain the porous carbon-supported nano metal material.

Wherein the carbon source is cellulose; the particle size of the alumina particles is 2 μm; the protective atmosphere is helium; the dilute acid solution is dilute sulfuric acid with the concentration of 0.5 wt%; the metal salt is an aluminum salt; the reducing atmosphere is hydrogen; the cleaning liquid is 40wt% ethanol water solution; the drying temperature is 110 ℃, and the drying time is 40 min; the stirring speed is 600 r/min.

Example four

The invention provides a method for loading a nano metal oxide or a nano metal material on porous carbon, which is different from the third embodiment in that the particle size of alumina particles is 1 mu m, and other conditions are the same.

EXAMPLE five

The invention provides a method for loading a nano metal oxide or a nano metal material on porous carbon, which is different from the third embodiment in that the particle size of alumina particles is 4.5 mu m, and other conditions are the same.

In order to detect the advantages and disadvantages of the porous carbon supported nano metal/metal oxide prepared by the embodiments, the invention respectively tests the aperture, specific surface area and compressive strength of each porous carbon supported nano metal. The aperture is obtained by counting the apertures of 25 holes and calculating the average value by taking a scanning electron microscope image of a sample. The specific surface area is calculated by using an absorption and desorption curve of a sample detected by a BET nitrogen adsorption method. The compressive strength is the stress-strain curve of a sample which is subjected to extrusion test by using a universal testing machine, and the compressive stress of the sample when the sample resists the maximum deformation is recorded.

Through comparison experiments on the five groups of examples, the porous carbon-supported nano metal material with excellent purity and performance can be prepared by each group of examples, and specific data are shown in table 1. The ratio of the porous carbon loaded with the nano metal prepared by the invention can be seenThe surface area is 700 m²The compression strength is about 25 MPa, wherein the maximum compression strength of the third example can reach 26.3 MPa, and the pore diameters of the porous carbon-loaded nano metal and Al can be seen in the third, fourth and fifth comparative examples₂O₃The grain diameter is not greatly different, and the difference between the grain diameter and the grain diameter is approximately in linear relation with the soaking time of the graphitized solid in the molten liquid, so that the Al can be adjusted according to actual needs₂O₃The particle size and the soaking time are used for obtaining the porous carbon loaded nano metal/metal oxide with specific pore diameter.

TABLE 1

Comparative example 1: the difference from the third embodiment is that two steps (1) and (2) in the preparation method are eliminated, and the phenolic resin and the metal salt are mixed and melted and then directly carbonized at high temperature. It can be seen that the porous graphitized solid is not used as a carrier, the pore size range of the prepared porous carbon-loaded metal composite material is wider and is uncontrollable, and the specific surface area and the compressive strength are also greatly reduced.

Comparative example 2: the difference from the third example is that the graphitization temperature in the step (2) is 2100 ℃. Due to the fact that the high temperature enables a large number of short-range ordered graphitized networks to be continuously connected, a long-range ordered structure is formed, porosity is greatly reduced, specific surface area is reduced, and toughness is improved.

Comparative example 3: the difference from the third embodiment is that the alumina particles are replaced by the aluminum carbide particles, and the particle size and the doping amount are not changed. The doped aluminum carbide particles can also play a supporting role in the graphitization process of the carbonized solid, the compressive strength of the finally prepared porous carbon-supported metal composite material is not greatly influenced, but the amorphous carbon remained in the pores is not effectively removed, so that the pore size distribution is widened, and the specific surface area is reduced.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.