JPS6019034A - Chemical reaction apparatus using composite plasma - Google Patents

Abstract

PURPOSE:To obtain a high purity homogenous reaction product, by rapidly performing reactive substances at the lower end of a plasma flame while rapidly cooling the temp. of the plasma flame in injecting the second reactive substance to suppress the formation of the reaction product. CONSTITUTION:A DC arc plasma torch 17 is provided to one end of an elongated pipe 7 comprising a heat resistant and corrosion resistant electric insulating material and an introducing means 6 opened around the arc plasma jet generated from said torch 17 and continuously supplying a first reactive substance such as SiCl4 is arranged. In addition, to the other end of an air-tight reaction chamber which is present in a region for performing joint action along with the above mentioned arc plasma jet and comprises a high frequency induction coil 18 having a center axis common to the torch 17, an injection means, which similarily has said center axis common to said torch 17 and is present in the plane vertical to said center axis and uniformly inject a second reactive substance such as NH3 from the outer periphery of the above mentioned plasma jet in the vicinity of the trailing part of said jet toward the center of the plasma flame to allow the same to react with the first reactive substance as well as to rapidly cool the plasma, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chemical reaction apparatus using composite plasma. The composite plasma referred to in this specification means one in which a high-frequency gas plasma is superimposed on a DC arc jet, and does not mean one in which IrIJ circumferential eL power is electromagnetically coupled to a DC arc jet. A chemical reaction device that combines arc plasma with high-frequency power was developed in Japanese Unexamined Patent Publication No. 5
Its features and effects are disclosed in Kokodo No. 5-32317. However, in the apparatus described in this publication, the raw material used for the desired reaction is introduced into the plasma in the form of a mixture from the two ends of the coupled plasma toward the direction F, so that the temperature distribution within the plasma changes. This has the disadvantage that it is difficult to obtain a product made of uniform particles because the thermal history and reaction history of each particle of the reaction product are different.

Furthermore, the energy required to maintain the plasma in order to simultaneously introduce the first raw material material and the second raw material material is
It is larger than when only the first raw material is introduced,
Therefore, there is a drawback that the plasma flame tends to become unstable.

The present invention focused on these shortcomings, and as a result of intensive research, the present invention was completed.

In the present invention, quartz is used for the elongated tube made of a highly corrosion-resistant electrical insulator into which the first raw material is introduced and on which the DC arc plasma torch is mounted.

Gases used for direct current and high frequency plasma generation include Ar, N2... depending on the type of reaction. A reactive gas such as N2.02 may also be used.

Chemical reactions for which the apparatus of the present invention can be used include reduction reactions in il'f fields and thermal decomposition reactions of higher hydrocarbons.

These include multi-component synthesis reactions, production of fine powders, production of amorphous bodies, etc. Therefore, when using the apparatus of the present invention, a plurality of raw materials are used for introducing the raw materials, and the raw materials are divided into two parts, the first and the second, and injected into the reaction chamber. for example. In the case of decomposition of higher hydrocarbons, the first reactant is the hydrocarbon itself, and the second reactant is an inert gas such as Ar or N2 for cooling. used for.

Regarding the order of introduction of the first and second raw materials, the most advantageous method for the reaction is used in consideration of the respective reaction mechanisms, and will be specifically explained in the following examples.

The high-frequency induction coil used to generate composite plasma is usually made using copper pipes, and this coil is manufactured using the usual method 1.
A high frequency current of several kilohertz to several megahertz radio frequency obtained by oscillation, buffer, and middle circuit is passed.
In this case, this coil can be the output coil of an induction circuit coupled to a tank coil in a power multiplier circuit. Therefore, the number of turns of this coil is appropriately designed according to each frequency used.

Gas plasma is generated along the center line of this high-frequency induction coil, and at this time, the plasma flame at least one plane perpendicular to the center line of the plasma and located symmetrically with respect to the center of the plasma.
An annular second reactant injection member having pores or slits is provided. This member must be inert to the reaction system in the reaction tube and heat resistant, but it is usually used after being cooled with water.

A chemical reaction apparatus using the above-described composite plasma will be explained with reference to the attached FIG. 1.

1 in FIG. 1 is an arc plasma gas inlet, and 2 and 3 indicate one side and the + side of a DC arc generating power source, respectively. Although not shown, the direct current torch is accompanied by a conventional type of high frequency igniter to facilitate ignition.

When operating the device, the conduit 4 leading to the vacuum pump
After the air inside the device is removed to create a vacuum, gas is introduced from the arc plasma gas inlet 1, and a DC torch is ignited by a high frequency ignition device to obtain safe arc plasma. On the other hand, a high-frequency plasma gas is flowed through the inlet 13, and a high-frequency current of a constant frequency and constant output is passed through the high-frequency induction coil from a high-frequency generator (not shown) to generate high-frequency gas plasma. When a composite plasma consisting of the following is stably obtained at normal pressure, first, a second reactant is injected into the plasma from the second reactant inlet 5.

Since this second reactant is introduced in large quantities at room temperature, the plasma temperature is rapidly cooled, and the plasma below the introduction port 5 disappears. During this time, the temperature within the composite plasma is maintained at a temperature of approximately 8700'.

Next, the first reactant is introduced from the first reactant inlet 6 and separated by being exposed to high temperature within the composite plasma, and the decomposition products rapidly react with the second reactant and leave the reaction system. This first reactant may be not only a single substance but also a mixture of k number components. The first reactant and the second reactant are preferably fluids, preferably gases, that can be uniformly introduced into the plasma flame.

As mentioned above, the reaction mechanism in plasma is different from the normal chemical reaction mechanism because it takes place at an extremely high temperature compared to normal chemical reactions that use heating by combustion or heating by electrical Joule heat. many.

The reaction products that have left the reaction chamber go through the necessary steps such as air cooling, water cooling, washing, and collection as in the case of ordinary chemical reactions, and become products. Plasma scum, unreacted gas, etc. are recycled as desired. Reused.

It should be noted here that the reaction between the reactants of the first and second reactants takes place rapidly at the lower end of the plasma flame, and the injection of the second reactant rapidly cools down the temperature of the plasma flame. It is characterized by the ability to suppress the formation of η-formation of side reactants and to obtain a highly pure and homogeneous reaction product.

Although the first reactant introduction device 1 has a pair of left and right openings in the attached FIG. 1, it does not necessarily have to have two openings or slits, and may have one or more openings or slits.

Hereinafter, the reaction apparatus of the present invention will be explained in detail with reference to the following examples with reference to the accompanying drawings.

Example 1 In the attached FIG. 1, the reaction tube 7 has a thickness of 21111. Inner diameter 4
5. It consists of a quartz tube with a length of 160 mm, and its upper and lower ends are hermetically sealed via a ring-shaped water cooling tube to cool both ends and the vessel wall, and water is supplied from the lower ring 8. L
It flows into the ring 9 and cools the lower end of the quartz tube and the torch wall. - The inner part of the water cooling ring has an outer diameter of 4QII.
m DC arc torch 17, consisting of a tungsten cathode and a copper anode. This DC torch 1 has an opening 1 for introducing Ar for arc plasma formation, and near the outlet nozzle of the DC torch there is an inlet 6 for introducing the first reactant 5iC64 to which Ar is added as a carrier.
0 and 51 diameter) are arranged to face each other, and an inlet 13 for a high-frequency plasma gas made by adding hydrogen to Ar is provided at the L portion of the reaction tube 7. On the other hand, on the lower side of the water-cooled ring in the Y part, there is an annular second raw material introduction member 5 having slits arranged in a circumferential manner in Q and Q7 vP toward the inside of the reaction chamber, and both of these are connected to the reaction tube 7. is hermetically sealed.

The F of the reaction tube 7 on which the above plasma torch is mounted is 40
There is a box-shaped JacuSoto 10 made of #lq, measuring 40 cm by 60 cm, and its center coincides with the center of the reaction tube.

In the center of the jacket, directly below the reaction tube, an inner diameter IQ cm,
Duplex 1 made of hard glass or quartz with a height of 5Qcm
1 is fitted and passed inside the jacket at its lower end and connected to an air outlet 1]4 to a vacuum pump which eliminates the pressure inside the apparatus and to an outlet 12 for the gas remaining after the reaction -4.

A double cylindrical water cooling section is provided concentrically between the hard glass tube and the side surface of the jacket on the bottom of the jacket to cool the lower part of the jacket. 14 and 15 indicate the inlet and outlet of the cooling water of the reservoir. Reference numeral 16 is a thermocouple type thermometer for measuring the temperature on the surface of the hard glass tube.

In the above apparatus, 8R was passed through a DC arc torch placed on the upper part of the reaction tube 7 at a rate of 2.7XIO-9kg/sec, and ignited using a known type of high-frequency ignition device, resulting in a manual effort of 10K.
A stable DC arc plasma is obtained with W, and at the same time, a mixed gas of Ar and 112 is introduced from the gas inlet 13 with Ar being 5-8
10' kg/sec, I+ 2 is 6,8x] ]0-
Flowing at a speed of about 7 kg/sec, a frequency of 5 M f (z plate output 14
A stable composite plasma was obtained by passing a high frequency current of KW.

At this time, by mixing H2, the high frequency plasma becomes a reducing atmosphere, and the radius of the plasma flame is also reduced to prevent energy loss and thermal damage to the surrounding vessel wall material due to rlH conduction.

Next, 23×10 N113 was added from the second raw material introduction port 5.
When the plasma flame tp is injected from all four directions at a speed of ~"kg/sec, the injected part is rapidly cooled and the plasma below the injected part disappears.

After that, a mixture of SiCβ4P and Ar was fed through the first reactant inlet 6 at a rate of 10 kg/sec.
When injected at a rate of xlO-ηkg/sec, the reaction product is
It was deposited inside a hard glass tube 11 at a temperature of 550°. At this time, the amount of by-products NH and C1 was suppressed to 2-3% by weight or less (this N tla CQ
could be easily removed in vacuum or by heating to 573K in a N2 stream.The generated 3i3
N.1 was a soft and fluffy powder, S.Washi was a pure white powder, and its specific gravity was approximately 0.15 g/ca. The particle size of the powder was in the range of 10 to 30 nm, the average particle diameter was 20 nm, the shape was spherical, no stone particles of MMll were observed, and the reaction rate was 100%.

The obtained 5i3N,+ satisfies the requirements for ultrafine silicon nitride particles in terms of purity and particle size. The fact that it could be synthesized directly from 4 and NH3 was extremely surprising.

Si3N4 is an extremely useful ITI material as a refractory material.

It is also clear from the attached FIG. 1 that the device of the present invention can be used upside down or on its side.

Example 2 Homogeneous carbon 6↑= element consisting of ultrafine particles was prepared by the same method as in Example 1 except that CH4 was used instead of the second raw material N)13 used in Example I. 100
The reaction rate was close to %.

Examples 3 to 16 The first raw material and the second raw material in Example 1 were changed to the materials shown in Table 1 below.

Table 1 ] ”

[Brief explanation of drawings]

The attached FIG. 1 is a schematic diagram showing the apparatus of the present invention. Explanation of symbols 1, gas introduction for arc plasma 10 2, power terminal for arc torch cathode 3, power terminal for arc torch anode 4, gas to blue sky pump (nod outlet 5, second reactant inlet 6, First reactant introduced 1 7. Reaction tube (composite plasma reactor wall) 8. Cooling water inlet 9. Cooling water outlet 10. Jacket 11. Hard glass tube or quartz tube 12. After reaction exhaust gas outlet [3 , High-frequency plasma gas introduction I [4, cooling water inlet 15, cooling water outlet [6, thermocouple temperature old 17, arctorage procedure sleeve i1F, uran 11 (''Wa 5 (]) April 2016/' 7I 3 - Director-General's Notice 158 Year Patent Application No. 126795 Name Relationship between persons who operate chemical reaction equipment using synthetic plasma , Contents of the Detailed Description of the Invention and Brief Explanation of the Drawings column - r11' (1 Description 1 Name of the invention Chemical reaction device using composite plasma 2 Claims (1) Heat resistant and corrosion resistant a DC arc plasma torch at one end of an elongated tube made of a conductive electrical insulator, at least one introducing means that opens around the arc plasma jet generated by the torch and continuously supplies a reactant; , and the other end of the airtight reaction chamber consisting of a high-frequency induction coil that is in the area that cooperates with the arc plasma sient and that shares the center line with the two-certified torch and that also shares the center line and is connected to the center line. in a vertical plane,
A liquid and/or gaseous second reactant is uniformly injected toward the center of the plasma flame from the outer periphery of a portion near the tail of the plasma jet to react with the first source material and rapidly cool the plasma. A chemical reaction apparatus using a composite plasma, characterized in that a second reactant injection means is provided having at least one opening or slit symmetrically provided with respect to the center of the plasma chef. (2) The first reactant is S+Cj'q, S]H4. 'Y+CRq, B2 H6, BC, L, S+l]C
e<. CHi 5iCjl! 3.5iFn, A, &2 Br
6. Δ&(13 or higher aliphatic hydrocarbon, first reactant plan:/)'NHa ,C+h ,N2 ,t-(,.C2+-16,C3i-io,(,H,,,C2N2
. CCIt h , CI = N +' (2 or CHn
2. The device according to claim 1, wherein the device has a temperature of 1.cN. (3) Adding hydrogen or other polymolecular gas to high-frequency plasma gasG! The device according to claim 1, wherein the device has Rj characteristics. 3. Detailed Description of the Invention The present invention relates to a chemical reaction device using composite plasma. The composite plasma referred to herein refers to a plasma in which a high-frequency gas plasma is added to a DC arc jet, and does not mean a plasma in which a high-frequency power is electromagnetically coupled to a DC arc jet. Special 13F111!3 is a chemical reaction device that combines arc plasma with high-frequency power.
Its characteristics and effects are disclosed in Japanese Patent No. 55-32317. However, in the apparatus described in this publication, the raw materials used for the target reaction are introduced into the plasma in the form of a mixture downward from the "binary value" of the coupled plasma. , since the thermal history and reaction history between each particle of the reaction product are different, is there a product made of uniform particles? There are seven disadvantages. Furthermore, since the first reactant and the second reactant are simultaneously introduced, the energy required to maintain the plasma is greater than when only the first reactant is introduced, and therefore the plasma flame is It has the disadvantage of being easily unstable. The inventor of the present invention has noticed these shortcomings and has completed the present invention as a result of intensive research. a direct current arc plasma torch, at least one introduction means opening around the arc plasma jet generated by the torch and continuously supplying the first reactant, and located on the outer periphery of the elongated tube and cooperating with the arc plasma jet; The other end of the gas-tight reaction chamber consists of a high-frequency induction coil that shares a center line with the torch and that is within the region of action and that also shares the vaginal center line and is in a plane perpendicular to said center line. A liquid and/or gaseous second reactant is uniformly injected from the outer periphery of the portion near the tail of the plasma chef) toward the center of the plasma flame to react with the first source material and generate plasma. The present invention relates to a chemical reaction apparatus using a composite plasma, characterized in that a first reactant injection means is provided having at least one opening or slit symmetrically provided with respect to the center of the plasma jet so as to rapidly cool the plasma jet. In the present invention, the elongated tube made of a heat-resistant, corrosion-resistant, and non-corrosion-resistant electrical insulator into which the first reactant is introduced and where the direct current arc plasma stage is placed is made of 4' or poron nitride. Gases used for direct current and high frequency plasma gas include reaction (Φ) gases such as A5H2, N2, 02
Equireactive gases may also be used. Chemical reactions that can be carried out using the apparatus of the present invention include reduction reactions at high temperatures, such as hydrogen reduction of halide residues, and thermal decomposition reactions of higher hydrocarbons, such as the production of acetylene and methane from heavy oil.
JJ production, production of carbon black from natural gas, Cn H+n, etc., synthesis of multi-component systems such as synthesis of Xialon, M production of fine powders such as pure metal alloys, ceramics,
Production of ultrafine particles of oxides, carbides, etc., amorphous bodies, for example, ceramic alloy fine particles, etc. Therefore, when using the apparatus of the present invention, a plurality of reactants are used for introducing the reactants, and these reactants are injected into the first and second reaction chambers separately. For example, in the case of decomposition of higher hydrocarbons, the first reactant is hydrocarbon itself, and the second reactant is an inert gas such as △r ((1 gas) or N2, etc.). The order in which the first and second reactants are introduced is determined by considering the respective reaction mechanisms and using the most advantageous method for the reaction, as will be specifically explained in the Examples below. The high-frequency induction coil used to generate composite plasma is usually made using copper pipes, and this coil is manufactured using the usual method 1.
A radio frequency current of several hundred kilohertz to several megahertz is passed through the oscillation, buffer, and intensifier + lJ circuits, but in this case, this coil is the output side coil of the induction circuit coupled to the tank coil in the power intensifier RI circuit. can be used. Therefore, the number of turns of this coil is appropriately designed according to each frequency used. Gas plasma is generated along the center line of this high-frequency induction coil, and at this time, the center line of the plasma flame A second reactant injection means, for example annular, is provided having at least one pore or slit in a plane perpendicular to and symmetrically located with respect to the plasma center. This means must be inert to the reaction system in the reaction tube, old and heat resistant;
Usually used after cooling with water. A chemical reaction apparatus using the above-described composite plasma will be explained with reference to the attached FIG. 1. 1 in Figure 1 is arc plasma gas introduction ['', and 2
3 and 3 are on the = side of the power source for reconnaissance generation.''
- indicates side. Although not shown, this DC torch is equipped with a conventional type of ignition device that utilizes high frequency waves to facilitate ignition. To operate the device, the conduit C is connected to the conduit 4 leading to the vacuum pump.
After the air inside the device is removed to create a vacuum, the conduit 4 is closed and normally an inert gas is introduced to bring the pressure to atmospheric pressure. Next, conduit 1
2 is opened, gas is introduced from the arc plasma gas inlet 1, and a DC torch is ignited by a high frequency ignition device to obtain safe arc plasma. On the other hand, a high-frequency plasma gas is flowed from the inlet 13, and a high-frequency current of a constant frequency and constant output is passed through the high-frequency induction coil from a high-frequency generator (not shown) to generate high-frequency gas plasma. When a composite plasma consisting of the following can be stably obtained at normal pressure, first the second reactant is introduced, and from =15, the first reactant is injected into the plasma. Since this second reactant is introduced in large quantities at room temperature, the plasma temperature is rapidly cooled, and the plasma below the cough introduction port 5 disappears. During this time, the temperature within the composite plasma is maintained at a temperature of 3700" or above.Then, the first reactant is introduced from the first reactant inlet 6, is exposed to high temperature in the composite plasma, decomposes, and becomes vapor. Alternatively, the decomposition product rapidly reacts with the second reactant and leaves the reaction system.This first reactant may be a mixture of not only a tunic substance but also a plurality of components.This first reactant and the second reactant
The reactant is preferably a fluid, preferably a gas, that can be uniformly introduced into the plasma flame. Also, in some cases, the first
It may be necessary to inject the reactant and the second reactant at the same time. As mentioned above, the reaction mechanism in plasma is different from the normal chemical reaction mechanism because it takes place at an extremely high temperature compared to normal chemical reactions that use heating by combustion or heating by electrical Joule heat. many. The reaction products that have left the reaction chamber undergo the necessary steps such as air cooling, water cooling, washing, and collection as in the case of a normal chemical reaction, and become products. Plasma gas, unreacted gas, etc. are circulated as desired. Reused. It should be noted here that the reaction between the reactants of the first and second reactants takes place rapidly at the lower end of the plasma flame, and the injection of the second reactant causes the temperature of the plasma flame to cool rapidly. It suppresses the formation of side reactions and has extremely high purity.
It has the characteristic of being able to iW a homogeneous reaction product. The first reactant inlet has a pair of left and right openings in Figure 1, but it does not necessarily have to be two and may have one or more openings or slits. The reaction apparatus of the invention will be explained in more detail with reference to the following Examples and the accompanying drawings. Consists of +nm quartz tube,
Its upper and lower ends are hermetically sealed via ring-shaped water-cooled pipes to cool both ends and the torch wall, and water flows from the lower link 8 to the upper link 9 to cool the upper and lower ends of the quartz tube and the torch wall. Cooling. Inside the upper g15 water-cooled ring is a DC arc torch 17 with an outer diameter of 40 mm, consisting of a tungsten cathode and a copper anode. This DC torch has an opening 1 for introducing Ar for arc plasma formation.
Near the outlet of the DC torch, there is an inlet 6 ([], 55 mm diameter) for the first reactant S+Cj2+ to which Ar is added as a carrier, and the upper part of the reaction tube 7 is arranged so that they face each other. is provided with an inlet 13 for high-frequency plasma gas made by adding hydrogen to Ar.On the other hand, below the lower water cooling ring, a 0.07 mm
There is an annular second reactant introducing means having a diameter of 11 mm in diameter disposed circumferentially, and both of these are hermetically sealed in the reaction tube 7. There are 40
Box steel jacket 10 x 40 x 60 cm
, and its center coincides with the center of the reaction tube. In the center of the cough jacket, there is an inner diameter IQc directly below the reaction tube.
A tube 11 made of hard glass or quartz with a height of 60 cm is installed, the lower end of which leads into the interior of the jacket and which leads to an air outlet 4 to the vacuum pump which eliminates the pressure inside the apparatus and during the reaction. It is connected to the gas outlet 12. At the bottom of the jacket, a double cylindrical water cooling section is provided concentrically between the hard glass tube described in 1. and the side surface of the jacket to cool the lower part of the jacket. 14 and 15
does not indicate the cooling water population and outlet for that purpose. Phase number 16 is a single-couple type thermometer that measures the temperature on the surface of a hard glass tube. In the apparatus described in -1-, 2.7 X l O-'kg/
2 seconds, and ignited it with a known type of high-frequency ignition device to obtain a stable DC arc plasma with 5 KW of human power. At the same time, a mixed gas of Ar and N2 was injected into the Ar
is 5-8 X I O-'kg/sec, N2 is 6.3X1
A high-frequency current with a frequency of 5 M l (z plate output of 14 KW) was passed through a copper pipe high-frequency induction coil wound three times at a flow rate of about 0'' kg/sec to obtain a -C stable composite plasma. By mixing, the high-frequency plasma becomes a reducing atmosphere, which reduces the radius of the plasma flame and prevents energy loss and thermal damage caused by heat conduction to the surrounding vessel wall feed. Reactant introduction "" NH3 from 5 to 23XIO
When injecting into the plasma flame from all four directions at a flow rate of -'kg/sec, the injected portion is rapidly cooled and the plasma below the -C1 injection time 19 minutes disappears. After that, a mixture of S+CC and Ar is supplied from the first reactant inlet 6 at 10-5 kg/sec and 27X 10-5, respectively.
When injected at a flow rate of kg/sec, the reaction product was deposited inside the hard glass tube 11 at a temperature of 550'. At this time, the amount of by-product NH,(l) was able to be suppressed to 2-3% by weight or less, but this NH4(l) can be easily removed by heating to 300°C or higher in vacuum or in a N2 stream. The 5iaNn produced was a soft and fluffy pure white powder, and the apparent specific gravity of C1 was approximately 0.15.
g/Cnt. The particle size of the powder is 10-301'1I
Tl range I] 1.1 11, hard glass tube or quartz tube 12, gas outlet 13, gas inlet for high-frequency plasma 14, cooling water population 15, cooling water outlet 16, thermocouple type thermometer 17, arc torch

Claims (3)

[Claims] (1) A DC arc plasma torch is attached to one end of an elongated tube made of a p% corrosion-resistant electrical insulator, and at least one first raw material substance used for a chemical reaction is continuously inserted into an opening around the arc plasma jet generated by the torch. an introduction means for supplying the plasma to the arc plasma Geno I;
・The other end of the airtight reaction chamber consisting of a high-frequency induction coil that shares the T1 core line with the T1 core line is located in a plane perpendicular to the center line and is close to the tail of the plasma jet. A liquid and/or gaseous second raw material is uniformly injected from the outer periphery of the part toward the center of the plasma flame to react with the first raw material and rapidly cool the plasma. A chemical reaction apparatus using a composite plasma, characterized in that it is provided with an annular FF12 source material injection means having at least one opening or slit arranged symmetrically with respect to the center of the plasma jet. (2) The first raw material used in the reaction is 5iCf
f4゜SiH4, TiCβa, B 2H6, B C
n3. 5iHC63, CH35iC123, SiF4゜A 1
2 B r 6 , A 7 ICI! 3 or higher aliphatic hydrocarbon, and the second reactant is NH3, CI4°N2. H2, C2H6, C3r (B, C, + 1110
゜C2H2, CCI! 4. The device according to claim 1, characterized in that it is CH3N H2 or CI (3CN). (3) The apparatus according to claim 1, characterized in that hydrogen or other polymolecular gas is added to the high-frequency plasma gas.