CN1270969C - Centimeter dimension tree shaped carbon and its preparation method - Google Patents

Abstract

A centimeter-scale dendritic carbon has a tree height of 1 to 10 cm and a crown diameter of 0.2 to 1 cm. The branches of dendritic carbon are formed by directional self-assembly of carbon particles with a diameter of 3 to 10 microns. The diameter of the branches is 2 to 10 microns, and the length is between 10 microns and 1000 microns. Heat the reactor to 900-1200°C under argon flow; heat the catalyst to 100-200°C to vaporize it; use argon to bring hydrocarbon solvent and catalyst into the reactor, React within the temperature range for 0.5 to 3 hours; reduce the temperature of the reactor to room temperature, and the dendritic carbon can be obtained. The invention has the advantages of simple equipment, less investment, simple operation and good repeatability, and the prepared dendritic carbon has large size and rich structure.

Description

A centimeter-scale dendritic carbon and its preparation method

technical field

The invention relates to a carbon material and a preparation method thereof, in particular to a centimeter-scale dendritic carbon and a preparation method thereof.

Carbon is one of the most important elements that constitute life systems in nature. There are six electrons outside the carbon nucleus, four of which are bondable electrons, which endow carbon with colorful shapes and many magical physical and chemical properties. For example, carbon atoms can form the diamond tetrahedral structure with the highest hardness through sp ³ hybridization; they can form graphite layered structures with heat resistance, electrical conductivity and self-lubrication through sp ² hybridization; or form carbene carbon through sp ¹ hybridization. More importantly, various hybridizations exist simultaneously to form fullerenes, onion carbons, and nanotubes with unique structures and properties, and these structural units can also form carbon materials of various shapes such as nanotubes through self-organization. Nanodendritic carbons (or carbon trees) are formed by self-organization. Therefore, the synthesis and application of new carbon materials has been a hot research topic for many years. Dendritic carbon is a new type of carbon material discovered in recent years with a branch structure or a straight rod structure, which looks like a "tree". The unique morphology and structure of dendritic carbon are generally formed by self-organization through some basic structural units. The preparation and research of dendritic carbon is of great significance in the aspects of material self-organization, tailoring and fractal theory. At the same time, dendritic carbon has a unique morphology and structure, and has great potential in the fields of composite material reinforcement, adsorption, separation and sensors. potential application prospects.

Studies on dendritic carbon have been reported in the literature. Ajayan et al. from Rensselaer Institute of Technology in the United States reported a method for preparing carbon micro-trees (Nature, Vol.404, 243). The method is to form carbon micron trees in rapid discharge on the graphite electrode surface (temperature is 1100-2200 DEG C, reaction gas is a mixture of methane and helium, and pressure is 500 torr). The technology is characterized by very high heating and cooling rates (hundreds of degrees per second), and the obtained carbon tree is a straight rod structure without branching structure, and the tree height is about several hundred microns. Yoshiki Shimizu et al. from the Institute of Advanced Industrial Science and Technology in Japan reported a dendritic carbon by first depositing a Ni-Mo catalyst on a silicon substrate, and then introducing a methane content of 5% into a DC plasma assisted heating system. Cedar-like carbon with a height of several microns was prepared after chemical vapor deposition using a mixed gas of methane and nitrogen. This new type of dendritic carbon is composed of carbon nanotubes. In addition, Chinese patent (02122640.) also discloses a preparation method of dendritic carbon nanotubes. The main feature of this invention is to put the quartz boat containing the cobalt/magnesia supported catalyst into the center of the quartz reactor, raise the temperature to 850-1100°C under the hydrogen atmosphere, and then feed the mixed gas of methane and hydrogen to react for 1-20 Minutes, and dropped to room temperature under the protection of hydrogen, dendritic was obtained after acid washing, however, with rich branched structure. However, macroscopic carbon dendrites with a length of several centimeters and their preparation methods have not been reported.

Contents of the invention

The object of the present invention is to provide a dendritic carbon with a rich branch structure and a centimeter-scale length and a preparation method thereof.

The dendritic carbon of the present invention is characterized by tree nanotubes. The reaction process uses a mixed gas of methane and hydrogen, and its volume ratio ranges from 1:2 to 8. The height of the tree is 1-10 cm, and the diameter of the crown is 0.2-1 cm. The branches of dendritic carbon are formed by directional self-assembly of carbon particles with a diameter of 3-10 microns. The diameter of the branches is 2-10 microns, and the length is 10 microns. to 1000 microns.

Branches can also grow on the branches of the dendritic carbon of the present invention to form a rich branch structure, and the diameters of the branches of the same tree are similar.

The preparation method of the invention adopts the catalytic pyrolysis method of hydrocarbons to prepare a centimeter-scale dendritic carbon material.

The present invention is realized by following method:

(1) Heating the reactor to 900-1200°C under argon flow;

(2) Heating the catalyst to 100-200°C to gasify it;

(3) The hydrocarbon solvent and the catalyst are brought into the reactor with argon, wherein the flow rate of the catalyst is 0.02-0.6 mg/min.cm2, the flow rate of the hydrocarbon solvent is 1-20 mg/min.cm2, and the argon The gas flow rate is 30-240 ml/min·square centimeter, and the reaction is carried out at a temperature range of 900-1200°C for 0.5-3 hours;

(4) Under the protection of argon flow, the temperature of the reactor is lowered to room temperature, and the dendritic carbon can be obtained.

The catalysts used in the present invention are volatile transition metal organic compounds, which include ferrocene, cobaltocene or nickelocene.

The hydrocarbon solvents used in the present invention include aromatic hydrocarbons such as benzene or toluene and aliphatic hydrocarbons such as hexane, pentane or cyclohexane and the like.

Advantages of the invention

1. Simple equipment, low investment and simple operation.

2. Mature technology and good repeatability.

3. The prepared dendritic carbon has large size and rich structure.

Illustration

Figure 1 is a scanning electron microscope image of a dendritic carbon treetop prepared by the present invention. The treetop in the photo is about 2 mm long and has a rich branch structure.

Figure 2 is a partially enlarged scanning electron microscope image of the dendritic carbon. The photos show that the branches are mainly formed by directional self-assembly of carbon spheres with a diameter of about 5 microns. The diameter of the branches is equivalent to the diameter of carbon particles, and the length ranges from tens of microns to hundreds of microns. All branches are similar in diameter.

Detailed ways

Example 1:

Weigh 0.1 g of ferrocene, put it into a porcelain boat with a width of 3 cm and a length of 6 cm, and heat to 110°C. The temperature of the reactor was raised to 900° C. under an argon atmosphere, and then, the vaporized ferrocene and toluene were brought into the constant temperature zone of the reactor with argon. Wherein, the flow rate of ferrocene is 0.04 mg/min·cm2; the flow rate of toluene is 1 mg/min·cm2; the flow rate of argon is 30 ml/min·cm2. React at 900°C for 3 hours, turn off the reaction gas, and cool to room temperature in an argon flow to obtain a dendritic carbon with a length of 5 cm.

Example 2:

Weigh 0.2 g of ferrocene, put it into a porcelain boat with a width of 3 cm and a length of 6 cm, and heat to 130°C. The reactor was heated up to 1000°C under an argon atmosphere, and then, the ferrocene and toluene were brought into the constant temperature zone of the reactor with argon. Wherein, the flow rate of ferrocene is 0.26 mg/min·square centimeter; the flow rate of toluene is 3.6 mg/min·square centimeter; the flow rate of argon is 80 ml/min·square centimeter. After reacting at 1000° C. for 1 hour, turn off the reaction gas, and cool to room temperature in an argon flow to obtain a dendritic carbon with a length of 7 cm.

Example 3:

Weigh 0.3 g of nickelocene, put it into a porcelain boat with a width of 3 cm and a length of 6 cm, and heat it to 180°C. The temperature of the reactor was raised to 1100° C. under an argon atmosphere, and then, the vaporized nickelocene and xylene were brought into the constant temperature zone of the reactor with argon. Wherein, the flow rate of nickelocene is 0.14 mg/min·cm2; the flow rate of xylene is 10 mg/min·cm2; the flow rate of argon is 130 ml/min·cm2. After reacting at 1100° C. for 3 hours, turn off the reaction gas, and cool to room temperature in an argon flow to obtain a dendritic carbon with a length of 10 cm.

Example 4:

Weigh 0.5 g of cobalt dicene, put it into a porcelain boat with a width of 3 cm and a length of 6 cm, and heat it to 200°C. The temperature of the reactor was raised to 1200°C under an argon atmosphere, and then, the vaporized cobaltocene and hexane were brought into the constant temperature zone of the reactor with argon. Wherein, the flow rate of the cobalt dicene catalyst is 0.34 mg/min·cm2; the flow rate of hexane is 18 mg/min·cm2; the flow rate of argon is 200 ml/min·cm2. After reacting under an argon atmosphere at 1200°C for 2 hours, turn off the reaction gas, and cool to room temperature in an argon flow to obtain a dendritic carbon with a length of 8 cm.

Example 5:

Weigh 0.2 g of ferrocene, put it into a porcelain boat with a width of 3 cm and a length of 6 cm, and heat to 130°C. The temperature of the reactor was raised to 1150° C. under an argon atmosphere, and then, the vaporized ferrocene and toluene were brought into the constant temperature zone of the reactor with argon. Wherein, the flow rate of the ferrocene catalyst is 0.54 mg/min·cm2; the flow rate of toluene is 10 mg/min·cm2; the flow rate of argon is 230 ml/min·cm2. After reacting at 1150° C. for 0.5 hour, turn off the reaction gas, and cool to room temperature in an argon flow to obtain a dendritic carbon with a length of 3 cm.

Claims (2)

1, a kind of tree-shaped carbon of centimeter scale, the height of tree degree that it is characterized in that tree-shaped carbon is 1～10 centimetre, crown diameter is 0.2～1 centimetre, the branch of tree-shaped carbon is, and to be that 3～10 microns carbon granule is directed by diameter form from group, the branch diameter is 2～10 microns, and length is between 10 microns to 1000 microns; Make by following method:

(1) reactor is heated to 900～1200 ℃ under argon gas stream;

(2) catalyzer is heated to 100～200 ℃, makes it gasification;

(3) with argon gas varsol and catalyzer are brought in the reactor, wherein the flow of catalyzer is 0.02～0.6 milligram of/minute square centimeter, the flow of varsol is 1～20 milligram of/minute square centimeter, the flow of argon gas was 30～240 ml/min square centimeters, 900～1200 ℃ temperature range internal reactions 0.5～3 hour;

(4) under the argon gas stream protection, the temperature of reactor is reduced to room temperature, can obtain tree-shaped carbon; Described catalyzer is a ferrocene, and dicyclopentadienylcobalt or nickelocene, varsol are benzene, toluene, hexane, pentane or hexanaphthene.

2, the preparation method of the tree-shaped carbon of a kind of centimeter scale as claimed in claim 1 is characterized in that comprising the steps:

(1) reactor is heated to 900～1200 ℃ under argon gas stream;

(2) catalyzer is heated to 100～200 ℃, makes it gasification;

(3) with argon gas varsol and catalyzer are brought in the reactor, wherein the flow of catalyzer is 0.02～0.6 milligram/minute. square centimeter, the flow of varsol is 1～20 milligram of/minute square centimeter, the flow of argon gas was 30～240 ml/min square centimeters, 900～1200 ℃ temperature range internal reactions 0.5～3 hour;

(4) under the argon gas stream protection, the temperature of reactor is reduced to room temperature, can obtain tree-shaped carbon;

Described catalyzer is a ferrocene, and dicyclopentadienylcobalt or nickelocene, varsol are benzene, toluene, hexane, pentane or hexanaphthene.

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