JPH01104834A - Production of carbon fiber - Google Patents

Abstract

PURPOSE:To obtain the titled fiber in high efficiency and yield, by mixing a carbon compound gas with catalyst particles and a specific radical generating substance as a reaction initiator and reacting in a hot preheating zone and then in a reaction zone. CONSTITUTION:A raw material gas such as methane, ethane and butadiene is mixed with (A) a reaction initiator consisting of a radical generating substance which is an aromatic compound (derivative) capable of forming benzene radical in the reaction atmosphere (e.g. chlorobenzene) and (B) catalyst particles such as ferrocene. The mixture is introduced into a preheating zone heated at 300-700 deg.C to generate benzene radical from the radical generating substance. The obtained mixture is introduced into a reaction zone heated at 800-1150 deg.C to accelerate the reaction and obtain the objective carbon fiber.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing carbon fiber, and in particular, a method for significantly improving the production rate and production speed when producing carbon fiber by a vapor phase growth method. Regarding the method.

[Prior Art] Conventionally, PAN-based and pitch-based carbon fibers have been commercially produced. However, the PAN system is expensive, and the pitch system has fatal drawbacks such as complicated processes and difficulty in controlling purchasing.

On the other hand, a vapor phase growth method has been proposed in recent years. Conventionally, vapor-grown carbon fibers are produced by placing a substrate made of porcelain such as alumina or graphite in an electric furnace, forming carbon growth nuclei, ultrafine particle catalysts such as iron or nickel on this, and then forming carbonization particles such as benzene on this. A method is known in which carbon fibers are grown on a substrate by introducing a mixed gas of hydrogen gas and hydrogen carrier gas and decomposing hydrocarbons at a temperature of 950 to 1300°C.

However, with this method, there are two issues: (1) the length is likely to be non-uniform due to subtle temperature irregularities on the substrate surface and the density of the surrounding fibers, and (2) the gas that serves as a carbon source is consumed by the reaction. As a result, the fiber diameter differs considerably between the inlet and the outlet of the reaction tube; (1) Since production occurs only on the substrate surface, the central part of the reaction tube does not participate in the reaction and the yield is poor; (2) Since there are processes that must be carried out independently, such as dispersing ultrafine particles onto a substrate, reducing them, growing them, and then taking out the fibers, continuous production is impossible, and therefore there are problems such as poor productivity.

Therefore, a method for manufacturing carbon fiber was proposed in which a mixed gas of a carbon compound gas, an inorganic or organic transition metal compound gas, and a carrier gas was reacted at high temperature (Japanese Patent Laid-Open No. 60-5
4998.60-54999.60-224816, etc.).

[Problems to be solved by the invention] However, the above-mentioned Japanese Patent Application Laid-Open No. 60-54998.60-5
Methods such as No. 4999.60-224816 had problems such as a low conversion rate of raw materials into carbon fiber as a product, that is, a low yield and a low production rate. for example,
The production rate of carbon fiber using the conventional method is 2 to 3 g/J! (Reactor volume)·Hr, and therefore there is a problem that the reactor becomes considerably large. Incidentally, in the past,
The reactor capacity of an apparatus that produces 1000 tons per year (in the case of continuous operation per year) requires a considerably large capacity of 42 to 63 tons.

[Means for Solving the Problems] The present invention solves the above problems and provides a method for producing carbon fibers that can significantly improve the production rate and production speed in a method for producing carbon fibers by vapor phase growth. The present invention provides a method.

The method for producing carbon fiber of the present invention includes a carbon compound gas,
In a method in which carbon is deposited in the form of fibers by bringing catalyst particles in a suspended state into contact with each other under heating, an aromatic compound or a derivative thereof, which generates benzene radicals in the reaction atmosphere, is added as a reaction initiator. It is characterized by:

The present invention will be explained in more detail below.

In the method of the present invention, an aromatic compound or a derivative thereof is used as a reaction initiator (or reaction promoter) to react a carbon compound as a raw material, and a benzene radical is reacted in a reaction atmosphere, preferably a hydrogen atmosphere. A substance to be generated (hereinafter sometimes referred to as a "radical generating substance") is added. Such substances include those having polar substituents such as halogen, hydroxyl group, nitro group, or amino group on the benzene ring such as phenol, cresol, aniline, nitrobenzene, chlorophenol, and chlorobenzene, and fused polycyclic compounds such as naphthol. Examples include those having the above polar substituents.

Among these, benzene derivatives having a halogen or hydroxyl group are particularly preferred.

It is preferable to add such a radical generating substance in an amount of about 0.1 to 10% by weight based on the carbon compound used as a raw material.

To carry out the method of the present invention, the raw material carbon compound, radical generating substance, and catalyst particles are sent to a preheating zone heated to a temperature of about 300 to 700°C, and benzene radicals are generated from the radical generating substance in the preheating zone. Let, also,
Activate the catalyst. After that, these mixtures were heated to 800
The mixture is sent to a reaction zone heated to a temperature of about 1,150° C., and the reaction proceeds in the reaction zone by the action of the benzene radicals generated in the preheating zone and the activated catalyst.

Note that the raw material carbon compound refers to all carbon compounds that can be gasified, including CCl4, CHCJ13, CH
Particularly useful compounds characterized by inorganic compounds such as 2C112, CH3CJ2, and C01C32 and organic compounds in general are aliphatic hydrocarbons and aromatic hydrocarbons. Also,
In addition to these, derivatives containing elements such as nitrogen, oxygen, sulfur, fluorine, iodine, phosphorus, and arsenic can also be used. Some specific examples of individual compounds include methane (natural gas may also be used), alkane compounds such as ethane, alkene compounds such as ethylene and butadiene, alkylene compounds such as acetylene, benzene, toluene, styrene, etc. aryl hydrocarbon compounds, aromatic hydrocarbons with condensed rings such as indene, naphthalene, and phenanthrene, cyclopropane,
Cycloparaffin compounds such as cyclohexane, cycloolefin compounds such as cyclopentene and cyclohexene,
Alicyclic hydrocarbon compounds having fused rings such as steroids,
Sulfur-containing aliphatic compounds such as methylthiol, methylethyl sulfide, dimethylthioketone, phenylthiol,
Sulfur-containing aromatic compounds such as diphenyl sulfide, sulfur-containing heterocyclic compounds such as benzothiophene and thiophene, as well as Class 4 hazardous materials under the Fire Service Act such as gasoline, although not for car bodies, Class 1 petroleum, kerosene, and turpentine. , secondary petroleums such as camphor oil and pine oil, tertiary petroleums such as heavy oil, and quaternary petroleums such as gear oil and cylinder oil can also be effectively used. It goes without saying that mixtures of these can also be used.

In the present invention, the catalyst includes an inorganic transition metal compound,
Examples include inorganic Si compounds, organic transition metal compounds, and organic Si compounds. What is this inorganic transition metal compound?
An inorganic compound of a transition metal that can be vaporized alone or is soluble in water or at least one kind of water or organic solvent (a carbon raw material compound may be used as the organic solvent) or can be suspended as fine particles. Targets are inorganic compounds of transition metals. Transition metals include iron, nickel,
Cobalt, molybdenum, vanadium, palladium, etc. are preferred, and iron is particularly preferred.

Examples of the former inorganic transition metal compound that can be vaporized alone include Fe (No) 4. FeCjZa, Fe (No)
2 Cf1% Fe (No) 2, Fe
(No)2I, FeFa, etc. are mentioned.

In addition to the compounds listed as the former, the latter include F
e (NO3)2, FeBr3, Fe (HCOO)s
,CzyH42FeNoO12,Fe(SO4)3
．． Fe (SCN)2, Fe (No) 3NHz, C
o (No)2 Cl3, N1 (No) Cj! , Pd
(No)2cj12. Representative examples include N1CIL2.

In the present invention, organic transition metal compounds include alkyl metals in which an alkyl group and a metal are bonded, allyl complexes in which an allyl group and a metal are bonded, π-complexes and chelates in which a carbon-carbon double bond or triple bond is bonded to a metal. It is an organic transition metal compound typified by type compounds. In addition, transition metals here include scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, tantalum, tungsten, rhenium, iridium, and platinum. However, among these, those belonging to Group I of the periodic table are particularly preferred, and among these, iron, nickel, and cobalt are particularly preferred, with iron being the most preferred.

Furthermore, in the presence of a sulfur-containing carbon compound or an inorganic sulfur compound, an inorganic compound of silicon can also be used. For example, the above-mentioned inorganic metal compounds in which the metal is replaced with St or silicon carbide may be used. Furthermore, various organosilicon compounds may also be used.

The organic silicon compound includes, for convenience, silane and halogen silane in addition to organic compounds having a silicon-carbon bond. Examples of organic compounds having a carbon-silicon bond include organosilanes such as tetramethylsilane and methyltriphenylsilane; organohalogensilanes such as chlorodifluoromethylsilane and bromotripropylsilane; Alkoxysilanes; organoacetoxysilanes such as diacetoxydimethylsilane and acetoxytripropylsilane; organopolysilanes such as hexaethyldisilane, hexaphenyldisilane, and octaphenylcyclotetrasilane; organohydrogenosilanes such as dimethylsilane and triphenylsilane; Cyclosilane represented by (SiH2)n; organosilazane such as triphenylsilazane, hexaethyldisilazane, hexaphenylcyclotrisilazane, etc.; cyclosilazane diethylsilanediol, triphenylsilanol, etc. represented by (S i N2 HN)n; organosilanols such as trimethylsilylacetic acid and trimethylsilylpropionic acid; organosilane carboxylic acids such as trimethylsilylacetic acid and trimethylsilylpropionic acid; silicone isocyanates such as trimethylsilicon isocyanate and diphenylsilicon diisocyanate; trimethylsilicon isothiocyanate , organosilicon isothiocyanates such as diphenylsilicon diisothiocyanate; organosilicon esters such as triethylsilyl cyanide; silthians such as hexamethyldisilthian and tetramethylcyclodisilthian; cyclosilicon represented by (SiH2S)n Examples include silthian; organosylmethylene such as hexamethyldisylmethylene and octamethyltrisylmethylene; organosiloxane such as hexamethyldisiloxane and hexapropyldisiloxane, but other compounds containing a carbon-silicon bond There may be. It is also possible to use mixtures of these.

Note that, in the present invention, catalyst particles (for example, dried fine powder) that have been generated in advance as fine particles may be introduced into the reaction vessel.

The carrier gas in the present invention refers to all gases that are not directly involved in the reaction. For example, N2 gas,
The gas is mainly N2 gas, NH3 gas, Ar gas, He gas, Kr gas, or a mixture thereof. Among these, N2 gas is usually used.

On the one end side, a radical generating substance supply pipe 15,
A pipe 16 for supplying a compound containing a substance that becomes catalyst particles;
A carrier gas supply pipe 18 and a carbon compound gas supply pipe 20 are connected, and these pipes 15
．． 15 flow control devices in the middle of 16, 18, and 20 respectively.
a,! 8a, 18a120a are provided.

Further, a carbon fiber collector 22 is connected to the other end of the reaction tube 10, and an exhaust gas extraction pipe 22 is connected to the carbon fiber collector 22.
4 is connected.

The carbon fibers produced in the reaction vessel are introduced into the carbon fiber collector 22 together with a carrier gas. As this collection method, various conventionally known methods such as gravity sedimentation method and electrostatic precipitation method can be employed. Note that the carbon fiber collector 22 also plays a role of cooling the generated carbon fibers. The carrier gas extracted from the carbon fiber collector 22 may be directly introduced into the exhaust treatment means and discharged, but it may also be purified and then circulated for use.

According to the present invention, carbon fibers having a length of usually about 0.1 to 500 mm and a diameter of about 0.1 to 300 μm are used in a reaction temperature range about 100°C lower than in the conventional method that does not use a radical generating substance. It can be easily produced with high production rate and production rate.

[Function] The gas phase generated carbon fiber has a skeleton structure of a condensation product of benzene rings. Therefore, the presence of benzene radicals, which are highly reactive benzene skeletons, in the reaction zone in an undestructed state is effective for improving the production rate and production rate.

In the present invention, a substance that generates benzene radicals is added as a reaction initiator, so this substance generates benzene radicals and increases the reactivity of the raw material and the growth rate of carbon fibers.
Furthermore, the reaction temperature can be lowered by activating the reaction.

Incidentally, in the case of a linear carbon compound, the chains are broken in the reaction zone, and the growth of carbon fibers cannot be promoted.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Example 1 A radical generating substance and a catalyst are mixed into a raw material gas, and first 6
After being sent to a preheating zone at 00°C, it was sent to a reaction zone at 900°C to produce carbon fibers.

The substances and reaction conditions used were as shown below.

Raw material: Benzene catalyst: Ferrocene carrier gas: N2 Raw material concentration: Svoβ% to N2 Radical generating substance: Phenol Radical generating substance addition rate: 4% (weight ratio to raw material) Pressure: Normal pressure Residence time: 1 minute in preheating zone (N°C conversion) Reaction zone 3 minutes (N°C conversion) Reactor: Preheating zone (made of quartz) 30 mm diameter x 200 mm length Reaction zone 30 mm diameter x 400 mm length The results are shown in Table 1.

Example 2 A reaction was carried out in the same manner as in Example 1, except that the radical generating substances and their addition rates were as shown in Table 1.

The results are shown in Table 1.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that no radical generating substance was used.

The results are shown in Table 1.

From Table 1, it is clear that according to the method of the present invention, carbon fibers can be produced in a short time and with high yield.

[Effects of the Invention] As detailed above, according to the method for producing carbon fibers of the present invention, carbon fibers can be produced at a high production rate and at a high yield. Moreover, it is also possible to lower the reaction temperature.

Therefore, according to the present invention, the reactor volume can be reduced in size, and raw material costs can be reduced due to improved yields, allowing efficient production.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of an apparatus suitable for carrying out the present invention. DESCRIPTION OF SYMBOLS 10... Reaction container, 15... Radical generating material supply pipe, 16... Catalyst supply pipe, 18... Carrier gas supply pipe, 20... Carbon compound supply pipe, 22... Carbon fiber trap collector.

Claims (1)

[Claims] (1) In a method in which carbon is precipitated in the form of fibers by bringing a carbon compound gas into contact with suspended catalyst particles under heating, an aromatic compound or its derivative is used as a reaction initiator, and under a reaction atmosphere A method for producing carbon fiber, which comprises adding a substance that generates benzene radicals.