JPS583965B2 - Continuous carbon fluorination method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a vibration transport device having a trough equipped with a weir as a reactor to bring carbon and fluorine gas into contact with each other to produce poly(
carbon monofluoride) or poly(dicarbon monofluoride) [hereinafter referred to as carbon fluoride]
This invention relates to a continuous carbon fluorination method for producing carbon.

Recently, carbon fluoride has been attracting attention as a new industrial material, and is used as an active material in high-energy primary batteries and as a solid lubricant in various fields such as lubricating oil, grease, paint, and eutectoid plating. The demand for them is increasing rapidly, and there is a strong desire to develop a manufacturing method suitable for mass production.

Conventionally, the method for producing fluorinated carbon is the so-called batch method, in which carbon left stationary in a reactor is reacted with fluorine gas diluted with an inert gas, and the product is taken out after all of the charged carbon has reacted. Also, a so-called continuous method has been attempted, in which carbon is moved in a rotary kiln and reacted with fluorine gas diluted with an inert gas, and the product is taken out.

However, the batch method has the disadvantage that the production efficiency is low and the production capacity per reactor floor area is small.

In other words, in order to increase production efficiency, it is necessary to charge a large amount of carbon (that is, thicken the carbon packed layer) because the thermal conductivity of carbon and the generated carbon fluoride (hereinafter referred to as powder) is low. The reaction heat removal efficiency is poor and the reaction heat is accumulated, making it extremely difficult to control the heat during the reaction, resulting in increased decomposition of the carbon fluoride during the reaction.

In addition, the method of thinning the carbon filling layer avoids the accumulation of reaction heat, but has the drawback that it takes time and effort to take powder into and out of the reactor, reducing the production efficiency of carbon fluoride.

In addition, in the reaction in the rotary kiln, although one of the drawbacks of the batch system, which is the continuous loading and unloading of powder, is solved, the thermal efficiency is low, and the effective heat transfer area is small, so the heat removal efficiency is also low.

Further, there are disadvantages in that the uniform mixing of the powder is insufficient, and moreover, the reactor per unit production is large and has a lot of wasted space, and its structure is complicated.

The inventors of the present invention have conducted extensive research in order to eliminate the drawbacks of the conventional method and provide a manufacturing method suitable for mass production of carbon fluoride. They discovered that the objective could be achieved by a method of continuously fluorinating carbon with fluorine gas, and completed the present invention.

That is, in the present invention, when carbon is fluorinated with fluorine, a vibration transport device having a trough provided with a plurality of weirs at intervals and a heater for heating the trough is used as a reactor. Powdered, small spherical, or small lump carbon is supplied onto a trough, and the carbon is vibrated and transported by the trough which vibrates in an obliquely upward direction and an obliquely downward direction with respect to the transport direction of the carbon, and the reactor. This continuous carbon fluorination method is characterized in that the fluorine gas introduced into the reactor is brought into contact with the reactor at 200 to 600°C, and the fluorinated product is taken out from the other end of the reactor.

As described above, according to the method of the present invention, a vibratory transport device having a trough provided with a plurality of weirs is used as a reactor,
By performing a fluorination reaction by passing fluorine gas in countercurrent while the powder is vibrating and moving, the vibration of the trough causes the powder to float in the air, which prevents contact between carbon and fluorine gas and dissipation of reaction heat. It is effective and removes the reaction heat very well, making it easy to control the heat of the reaction.

Furthermore, by providing a weir in the trough, the thickness of the powder layer and the amount of powder transported can be controlled arbitrarily, and the size of the reactor can be reduced.

Further, in front of the weir of the trough, the powder attempting to cross the weir is mixed in a swirling manner, and this swirling mixing contributes to uniform reaction.

In this way, this powder is transported over the weir in a sliding manner, and has various advantages such as easy heat control and the ability to produce uniform fluorinated carbon continuously without reducing the yield due to decomposition. Demonstrate.

In addition, in the method of the present invention, the structure of the reactor is simple and it is easy to increase the size of the reactor, and powder transport can be easily controlled by changing the amplitude of vibration or the angle of inclination of the trough. Body transport is smooth, there is no dust, and abnormal reactions such as dust explosions due to vibration do not occur.

As described above, the method of the present invention is industrially extremely advantageous as a mass production process for carbon fluoride.

It is completely contrary to common sense to use vibratory transport equipment, which was originally developed for the purpose of mass transport, as a reactor for the production of fluorinated carbon, which is extremely slippery and difficult to transport as a fine powder, and in fact, it is still used today. No such proposal is known.

However, the present inventors have provided a weir in the trough of a vibratory transport device that transports powder using a trough that vibrates obliquely upward and obliquely downward with respect to the transport direction of the powder.
Due to the special nature of this reaction, we were able to surprisingly succeed in developing a continuous carbon fluorination method that produces the remarkable effects mentioned above.

To give a preferred embodiment of such a vibration transport type reactor used in the method of the present invention, for example, the reactor includes a reaction chamber, a hopper for supplying carbon, and a hopper provided at one end of the upper part of the reaction chamber. A rotary feeder, a product receiver provided at the other end of the reaction chamber, a fluorine gas supply port provided at one end of the top of the reaction chamber, a reaction exhaust gas outlet provided at the other end of the top of the reaction chamber, the reaction chamber The reaction chamber consists of a vibration device for vibrating the reaction chamber, a heater for heating the inside of the reaction chamber, and a cooler provided to prevent the vibration device from being heated, and the reaction chamber has an upper ceiling or a lid and a lower trough. A plurality of baffle plates projecting downward are provided at intervals on the ceiling or the lid, and a plurality of weirs projecting inwardly and upwardly in the direction of travel are provided in the trough. The trough is provided with a heater and a cooler for cooling the vibration device on the outside thereof, and the vibration device has an electromagnet serving as a vibration source, and the electromagnet causes vibration through a leaf spring. The held trough is vibrated, and the powder in the reaction chamber heated by the heater is transferred from the hopper side to the product receiver side while gradually reacting with the fluorine gas in a countercurrent manner, and the reaction product is generated. is configured to be delivered to a product receiver.

Next, this will be explained using drawings.

FIG. 1 is a sectional view showing an embodiment of a vibration transport type reactor used in the present invention.

In Figure 1, 1 is a trough, 2 is a lid, 3 is a hopper,
3a is a rotary feeder, 4 is a product receiver, and 13 is a vibration device.

The trough 1 is provided with a plurality of weirs 8 that protrude inwardly and upwardly, and a heater 9 and a cooler 10 are arranged on the outside of the trough 1.

The lid 2 is provided with a plurality of baffle plates 7 that protrude downward,
Moreover, a hopper 3, a rotary feeder 3a, an exhaust gas outlet 6, and a fluorine gas supply port 5 are provided above the hopper 3.

A product receiver 4 has a flexible hose 1 at the other end of the trough.
4, and the product is taken out from the rotary valve 16 as appropriate.

The vibration device 13 has an electromagnet 12 and is configured to vibrate the trough 1 held via a leaf spring 11 by the electromagnet.

Note that 15 is a thermometer placed inside the trough.

Next, embodiments of the present invention using the above reactor will be explained.

Carbon fed from a raw material hopper 3 through a rotary feeder 30 is transferred on a vibrating trough 1 in the direction of a product receiver 4.

The carbon on the trough 1 comes into countercurrent contact with the fluorine gas supplied from the fluorine gas supply port 5, and a reaction takes place.

Vibratory transport of powder occurs when the electromagnet 12 is excited by a pulsating current from the controller of the vibrating device, and the trough 1 is suddenly drawn diagonally backward and downward, and the powder is suspended in the air due to its high velocity. Float and fall forward onto the trough due to gravity.

Then, the trough 1 is pushed back diagonally forward and upward by the force of the leaf spring 11, thereby moving the powder further forward.

At this time, the powder is mixed in a spiral in the weir 8 protruding above the trough, and the powder is smoothly moved as if sliding while coming into contact with the fluorine gas and reacting uniformly, and the reaction product passes through the flexible hose 14. The product is collected in the product receiver 4 through the product.

Further, the fluorine gas collides with the baffle plate 7 projecting below the lid 2, is changed direction, and is brought into sufficient contact with the powder on the trough.

Unreacted fluorine gas is exhausted from the exhaust gas outlet 6.

In the reactor used in the present invention, a vibrating trough is used as described above, and a plurality of weirs and baffle plates are provided at intervals above the trough and under the lid to prevent contact between carbon and fluorine gas. Since the reaction is conducted continuously and efficiently, carbon and fluorine gas can be used effectively, and the production capacity per floor area can be greatly improved.

Furthermore, since the mixing is good, an even reaction occurs.

In addition, when countercurrent contact is performed, carbon at the beginning of the trough (hopper side) is contacted with fluorine gas at a low concentration, so a rapid reaction does not occur, and the reaction progresses at the end of the trough (product receiver side). Because the highly concentrated fluorine gas comes into contact with carbon and reacts with it, the reaction efficiency can be increased.

The following conditions are preferably employed as the vibration transport conditions for powder in the present invention.

That is, the frequency of the trough is usually 1,800 to 1,800 per minute.
The powder on the trough can be smoothly transported by vibration in about 3,600 times, but the vibration width is 0.1~
lit1 is preferably in the range of 0.1 to 0.4 mm, so that the powder appears as if it were a stationary surface and can be moved smoothly.

When the shaking width is wider than 1 mm, a lot of powder is scattered.

The height of the weir provided on the trough is 1 to 6 mm, preferably 2 to 4 mm.

When the height of the weir is less than 1 mm, the powder layer becomes too thin and the area of the reactor needs to be widened;
When it is larger than m, it becomes difficult to move the powder and mix it uniformly, and the heat of reaction tends to accumulate.

The slope of the trough surface is defined as the slope on which the powder descends.
Taking the slope of the rising slope as one, a range of -4° to +4°, preferably +2° to 0° (0° is when the trough surface is horizontal) is adopted.

When the inclination of the trough surface is greater than -4°, the powder does not rise, and when it is greater than +4°, the powder slides like an avalanche, making transport control difficult.

Therefore, in the method of the present invention, the amount of powder to be transported, the transport speed, and the thickness of the powder layer are appropriately adjusted by the height of the weir, the width of the trough, the slope of the trough surface, etc.

In operating the vibration transport reactor used in the present invention,
Either a continuous vibration method (the trough is constantly vibrated during the reaction) or an intermittent vibration method (the trough is repeatedly vibrated and stopped during the reaction) can be used, and if necessary, multiple reactors can be connected. Of course, it is also possible to drive.

Further, as the material of the reactor, monel metal, nickel, etc. are usually used in consideration of the high reactivity of fluorine gas.

The carbon used in the present invention may be any carbon material, whether amorphous or crystalline.

Further, as for the form of the carbon material used in the present invention, it is generally preferable to use a powder form with an average particle size of 50 μm or less, but other forms such as small spheres and small lumps may also be used.

Furthermore, the method of the present invention can be applied not only to the method of fluorinating the entire carbon material, but also to the method of fluorinating a portion thereof, particularly near the surface.

The fluorine gas produced by electrolyzing KF/2HF molten salt is used as it is, or after removing HF as an impurity.

Commercially available fluorine gas in cylinders can also be used as is.

Fluorine gas is used alone, but because of its high reactivity, it is usually diluted with an inert gas such as nitrogen, argon, neon, perfluorinated hydrocarbon, air, or carbon dioxide to control the reaction. used.

The mixing ratio of fluorine gas and these inert gases can be changed as appropriate depending on the reaction conditions, such as flow rate and reaction temperature, but generally the fluorine gas partial pressure in the mixed gas is 0.5 to 0.0.
1, particularly preferably in the range of 0.4 to 0.1.

When the fluorine partial pressure exceeds 0.5, the reaction rate is too high and it becomes difficult to remove the reaction heat, increasing the amount of by-products such as perfluorinated hydrocarbons, while the fluorine gas partial pressure is 0.0.
When it is less than 1, the reaction rate becomes too low and production efficiency decreases.

The reaction temperature is usually 200~600℃, especially 200~
A range of 500°C is preferred.

Generally, the optimum temperature differs within the above reaction temperature depending on the type of carbon material, but the temperature of amorphous carbon is 200 to 450.
℃, and the ratio of crystalline carbon is preferably 400 to 500℃.

The method of the present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 8 A vibratory transport reactor as shown in FIG. 1 was used, which was equipped with a 10 cm wide x 80 cm long trough.

Weirs 8 with a height of 0.4 cm are provided on the trough at intervals of 10 cR.

The frequency of the vibration device 13 was 60 Hz.

Further, baffle plates 7 with a height of 2 cm are provided on the lid 2 at intervals of 20 cm.

A panel heater 9 is fixed to the outside bottom of the trough, and a cooling jacket 10 is installed between the electromagnet and the outside bottom of the trough to cut off heat.

First, the raw material carbon powder (petroleum coke type, 1 to 38μ) is put into the hopper 3 through the rotary feeder 3a, the reaction system is sealed, and after the carbon powder is sufficiently preheated,
Fluorine gas was supplied from the fluorine gas supply port 5, and a reaction for producing carbon fluoride [poly(carbon monofluoride)] was carried out under the reaction conditions shown in Table 1.

The fluorine gas used was diluted with nitrogen gas.

The reaction product was collected in the product receiver 4, and its production amount and fluorine content were quantified.

The results are shown in Table 1.

Examples 7 and 8 were conducted in the same manner as described above, except that continuous vibration was performed using a vibration transport type reactor incorporating a trough of 10 cm width x 200 cm length.

Example 9 The vibration conditions for the trough were as follows: the vibration width was Q, 3 mm, the vibration stop time was 5.5 minutes, the vibration time was 0.5 minutes, and the reaction temperature was 3 mm.
Carbon powder (
250 g of petroleum coke (1-38μ) was subjected to repeated fluorination reactions.

The results are shown in Table 2.

Example 10 The trough vibration conditions were as follows: oscillation width of 0.3 mm, vibration stop time of 5.5 minutes, vibration time of 0.5 minutes, and reaction temperature of 4 mm.
50°C, fluorine gas concentration 10 vol%, fluorine gas flow rate 3.

In the same manner as in Example 1 except that the flow rate was 8 l/min, 250 g of carbon powder (petroleum coke type, 38 μm or less) was subjected to repeated fluorination reactions.

The results are shown in Table 3.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a vibration transport type reactor used in the present invention. Main symbols in the drawing 1: Trough, 2: Ceiling or lid, 3: Hopper, 3a: Rotary feeder, 7: Baffle plate, 8
: Weir, 13: Vibrator, 5: Fluorine gas supply port, 6: Exhaust gas outlet, 9: Heater.

Claims (1)

[Scope of Claims] 1. When carbon is fluorinated with fluorine, a vibration transport device having a trough provided with a plurality of weirs at intervals and a heater for heating the trough is used as a reactor; Powdered, small spherical, or small lump carbon is supplied onto the trough from one end, and the carbon is vibrated and transported by the trough, which vibrates obliquely upward and downward with respect to the transport direction of the carbon. A method for continuous fluorination of carbon, characterized in that the fluorine gas introduced into a reactor is brought into contact with the fluorine gas at 200 to 600°C, and the fluorinated product is taken out from the other end of the reactor. 2. The method according to claim 1, wherein one weir is provided every 5 to 30 cm on the trough surface. 3. The method according to claim 1 or 2, wherein the height of the weir is 1 to 6 mm. 4. The method according to claim 1, 2 or 3, wherein the amplitude is 0.1 to 1 mm. 5. The method according to claim 1, 2, 3 or 4, wherein the fluorine gas is diluted with an inert gas. 6. The method according to claim 1, 2, 3, 4, or 5, wherein a baffle plate is provided on the ceiling surface or lid surface of the reactor.