JPS5857368B2 - Manufacturing method of boron trichloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improvement in a method for producing boron trichloride.

Boron trichloride is useful as a raw material for producing various boron compounds such as boron nitride and lanthanum boride, and catalysts for cationic polymerization.

Therefore, many methods for producing boron trichloride are already known.

For example, in U.S. Patent No. 2,369,212,
A homogeneous mixture of powdered diboron trioxide (B203) and carbon (C) is heat-treated at 1,200 to 1,300°C to form a porous sintered product, then crushed and sized, Flowing chlorine gas through the crushed material, 1. A method for producing boron trichloride by reaction with chlorine at temperatures between OOO and 1.200°C is described.

However, powdered boron trioxide and carbon have different properties, specific gravity, etc., so even if you try to mix them together, it is difficult to make a homogeneous mixture. However, in the conventional method, when the mixture is heat-treated at 1,200 to 1,300'C, diboron trioxide melts and liquefies, and diboron trioxide and carbon separate into two layers. Therefore, it is difficult to obtain a porous and uniform sintered product, and even if an attempt is made to react with chlorine, the reaction cannot proceed smoothly, which is a major drawback.

In addition, the conventional method not only requires crushing and sizing the sintered material, but also requires a high temperature of 1,000°C or more over two layers. If present in the reaction atmosphere during reaction,
The corrosivity of chlorine has become even stronger, and it can be used not only on metals, but also on metals.
There is also a big problem with the material of the reactor, as even glass corrodes.

Further, US Pat. No. 2,097,482 discloses that chlorine gas is passed through a mixture of carbon powder and a boron compound, for example, diboron trioxide, in an amount of 0.6 to 15 times the weight of carbon powder. A method for producing boron trichloride by reaction with chlorine at ~700'C is described.

In the method described in this US patent, the reaction temperature was 400°C.
Although the temperature is as low as ~700℃, the method of rice cracking is also similar to the above-mentioned U.S. Patent Nos. 2 and 3.
As with the method described in No. 69,212, it is very difficult to uniformly mix diboron trioxide and carbon powder, and even if it were possible to mix them uniformly, When chlorine gas is passed through, carbon powder tends to scatter, and during the reaction, diboron dioxide melts and liquefies, and due to the difference in specific gravity with the carbon powder, molten diboron trioxide accumulates at the bottom of the reaction tube, causing chlorine This method has major disadvantages in that it is difficult to carry out gas flow, diffusion, and uniform contact between diboron trioxide, carbon, and chlorine, making it impossible for the reaction to proceed smoothly and requiring a long reaction time.

In addition, prevention of scattering of carbon powder I4-. Even if an attempt is made to mold a mixture of diboron trioxide and carbon powder, the moldability is very poor if the carbon powder or activated carbon powder is used, and it is difficult to mold a mixture of the two.

Also, if carbon powder or graphite powder is used, is it possible to mold it?If such a molded product is used, the reaction time is extremely long. , nori, and diboron trioxide have extremely low reaction rates.

The inventors discovered that (1) the reaction can proceed smoothly even at low temperatures, (1) with a simple operation without the need for powder mixing, and (3) with a high yield in a short period of time. We conducted extensive research with the aim of producing boron trichloride at a low cost and (4) developing a method for producing boron trichloride that overcomes the drawbacks of the conventional methods.

As a result, using a boric acid aqueous solution and granular activated carbon, the boric acid-supported activated carbon obtained by impregnating the granular activated carbon with the boric acid aqueous solution was once heated to 30 to 80%
Granular activated carbon heat-treated at 0°C and chlorine are heated at 300~
It was discovered that the above object could be easily achieved by carrying out the reaction at 800°C, leading to the present invention.

In this invention, boric acid-supported activated carbon obtained by impregnating granular activated carbon with a boric acid aqueous solution is heated for 30 minutes in an inert gas atmosphere.
The present invention relates to a method for producing boron trichloride, which is characterized in that it is heat treated at 00 to 800°C and then reacted with chlorine at 300 to 800°C.

0) In the present invention, when reacting with chlorine, heat-treated boric acid-supported activated carbon obtained by impregnating granular activated carbon with a boric acid aqueous solution is used, so mixing of powders is not required as in the conventional method. No manipulation is required and the drawbacks caused by the method using a mixture of diboron trioxide and carbon powder can be easily overcome.

In addition, if powdered activated carbon is used, even if it is immersed in a boric acid aqueous solution, the activated carbon is loaded with boric acid, and the activated carbon is heat-treated in an inert gas atmosphere to react with chlorine. Since diboron trioxide melts, liquefies and separates, it becomes difficult for the chlorine gas to circulate and diffuse, the reaction does not proceed smoothly, and the reaction time becomes longer. However, there are disadvantages such as the fact that the separated activated carbon powder is entrained in the reaction product, and the above object of the present invention cannot be achieved (flb).

The granular activated carbon used in this invention may have any shape, such as spherical, columnar, or crushed granular, and its shape is not particularly limited.

The particle size of granular activated carbon depends on the reaction method, such as fixed bed or moving bed.
Although it varies depending on the size of the reactor and other reaction conditions, it is generally 1 to 50 rnrn, preferably 3 to 1
5mm is appropriate.

If the particle size becomes too small, the same drawbacks as those when using powdered activated carbon are likely to occur, and even if the particle size is too large, there is no particular advantage of increasing the particle size. A diameter of 0 is suitable.

In addition, carbon particles other than granular activated carbon, such as shaped graphite, cannot be sufficiently impregnated with an aqueous boric acid solution, and the reaction cannot proceed smoothly.
Furthermore, when graphite powder is molded by adding boric acid, the reaction rate of boric acid is extremely low and the reaction time is extremely long, making it impossible to achieve the above-mentioned object of the present invention.

The specific surface area of the activated carbon used in this invention is not particularly limited, but if the specific surface area is too small, the amount of boric acid supported will be small, and if the specific surface area is too large, the mechanical strength of the activated carbon will decrease. Generally, the specific surface area is 400 to 6,000 m2/g, preferably 1,000 m2/g.
0 to 4,000 m''/gb is appropriate.

Further, the concentration of the aqueous boric acid solution used in the present invention is not particularly limited, but it is generally appropriate to have a concentration of 5 to 28% by weight, or 10 to 25% by weight.

In this invention, a conventionally known impregnation operation is employed to impregnate the granular activated carbon with a boric acid aqueous solution.
Generally, the method involves soaking granular activated carbon in an aqueous solution of boric acid.
It is appropriate to impregnate granular activated carbon with a method such as spraying an aqueous boric acid solution.

If granular activated carbon that has been previously subjected to vacuum deaeration treatment is used during impregnation, the impregnation time can be shortened.

In (7) of this invention, the amount of boric acid supported on the boric acid-supported activated carbon can be adjusted by changing the concentration of the boric acid aqueous solution used, the specific surface area of the activated carbon, the impregnation time, the number of impregnation operations, etc. Generally, boric acid [H3BO3] is preferably supported in an amount of 10 to 80 parts by weight, preferably 20 to 60 parts by weight, per 100 parts by weight of activated carbon.

If the amount of boric acid supported is too small, productivity will deteriorate, and if the amount supported is too large, the amount of activated carbon consumed in the reaction will be too large, resulting in a decrease in the mechanical strength of activated carbon, breakage, powdering, etc. Since troubles are likely to occur, the amount of boric acid supported is preferably within the above range.

In this invention, the boric acid-supported activated carbon obtained by impregnating granular activated carbon with an aqueous boric acid solution is heated at 300-800°C, preferably at 400-600°C under an inert gas atmosphere.
It is necessary to perform heat treatment at 00°C.

Through heat treatment, boric acid decomposes and dehydrates to form diboron trioxide.

2H3BO3 → B2O3 → 3H20 If the heat treatment temperature is too low, boric acid will not be sufficiently decomposed and dehydrated, and water will be produced during the reaction with chlorine, resulting in a decrease in boron trichloride σ) yield. Even if the temperature is higher than necessary, especially when disassembling the
Since there is no difference in the dehydration effect between dogs, it is appropriate to carry out the heat treatment at a temperature within the above range.

The heat treatment time is not particularly limited as long as boric acid can be sufficiently decomposed and dehydrated, but is generally 1 to 20 hours.

The inert gas used during the heat treatment may be any gas that is inert to activated carbon, boric acid, diboron trioxide, etc. Typical examples include nitrogen, helium, and argon. Gases such as

Note that heat treatment in an oxygen-containing gas atmosphere, for example, in an air atmosphere, is not appropriate because the activated carbon may be burned.

In this invention, the heat treatment in an inert gas atmosphere is generally performed while an inert gas is flowing.

Also, heat treatment can be done at any time as long as it is done before reacting with chlorine).

The granular activated carbon obtained by the heat treatment in the inert gas atmosphere has a temperature of 300 to 800°C, preferably 400°C.
React with chlorine at ~600°C.

B2O3+3C+3C12→3CO+28CI3The reaction with chlorine may be carried out by any method as long as the chlorine and the heat-treated activated carbon can be brought into sufficient contact0)
However, this is generally carried out while circulating chlorine gas through the activated carbon layer.

When reacting with chlorine, if the reaction temperature is too low, the reaction time will be very long; if it is too high, there is no particular advantage to raising the reaction temperature, and it is not a good idea from a thermoeconomic perspective. Generally, the temperature is 300 to 800℃.
, preferably 400 to 600°C.

When the reaction with chlorine is carried out at the above temperature, the reaction proceeds smoothly and gaseous boron trichloride is produced.

The reaction time varies depending on the reaction temperature, the amount of supported boric acid, the amount of chlorine gas supplied, etc., but is generally 1 to 5 hours.

Boron trichloride can be easily recovered by methods known per se, such as condensation and distillation.

This invention can be carried out using any reaction method such as a fixed bed, a moving bed, or a fluidized bed, but it is appropriate to carry out the reaction using a fixed bed or a moving bed.

According to this invention, since granular activated carbon supported as boric acid or diboron trioxide obtained by the heat treatment is used for the reaction with chlorine, the circulation and diffusion of chlorine gas is easy, and the powder When a mixture of diboron oxide and carbon powder is used, the carbon powder may scatter, or the diboron dioxide may melt and liquefy during the reaction and separate from the carbon powder, leaving the melt at the bottom of the reaction tube. The reaction can proceed smoothly and be completed in a short time without slowing down, and boron trichloride can be produced in high yield.

Next, examples and comparative examples will be shown.

Example 1 1,100mj of water heated to 80℃! ! Then, boric acid (H
3BO3) 222.9 is dissolved, and granular activated carbon (branch diameter 3 mJ specific surface area 1,150 m"y"g) is dissolved in this.
] (After soaking J for 5 minutes, it was separated by lightning and dried at 160°C for 20 hours in an air atmosphere to form boric acid-supported activated carbon [H3
The amount of supported BO3 was 79.5 g], and this was filled into a quartz reaction tube with an inner diameter of 50 mm, and 3.000 ml of nitrogen gas was added.
The sample was heated while flowing at a flow rate of /mvt and heated at 500° C. for 3 hours to decompose and dehydrate the supported boric acid.

Next, replace nitrogen gas with chlorine gas at 900 m1/m1y.
It was passed through the reaction tube for 1.5 hours at a flow rate of t to react with chlorine, and the generated gas was cooled with dry ice [j. As a result of liquefaction and collection, the composition of the complement was 148 g of boron trichloride. The amount of chlorine was 13g.

The reaction rate of supported boric acid (hereinafter referred to as reaction rate) is:
100%, the yield of boron trichloride was 98% ○ Examples 2 to 6 90 ml of granular activated carbon similar to Example 1 was added to 100 ml of water heated to 80°C with 20 ml of boric acid [H3BO3] (
323 mmol) was dissolved in a boric acid aqueous solution for 5 minutes, and dried in an air atmosphere at 160°C for 20 hours to form boric acid-supported activated carbon [H3BO3 supported amount: 80
g) was obtained.

Next, a quartz reaction tube with an inner diameter of 24 mm was filled with 90 ml of boric acid-sustaining activated carbon, and 270 ml of argon gas was added! /
After heating while flowing at a flow rate of mvi and heat treatment at the temperature listed in Table 1 for 1 hour, chlorine gas was flowed in place of Alcon gas at a flow rate of 90 ml/ml yr, and chlorine and chlorine were heated at the same temperature as the heat treatment temperature. React, absorb the produced gas in water, add 50g of D-sorbit, and add IN-sodium hydroxide I.
The produced boron trichloride was determined by titration with a J aqueous solution.

The reaction time required until the reaction rate reached 100% is shown in Table 1.

In addition, the amount of boron trichloride produced is 130 m in both cases.
mol (approximately 15 g).

Example 7 After changing the impregnation time from 5 minutes to 30 minutes, the tamaka was heat-treated in the same manner as in Example 5, and then chlorine gas was flowed at a flow rate of 200 ml/mvt instead of argon gas to react with chlorine at 500°C. Ta.

The reaction time required for the reaction rate to reach 100% was 45 minutes, and the amount of boron trichloride produced was 22.5 minutes. j? (190
mmol).

Note that the amount of boric acid supported was 11.7 g.

Example 8 70g of boric acid [H3BO3] was added to 200r111 of water, heated to 97°C to dissolve the boric acid, and Example 1 was added to this.
Granular activated carbon similar to 90m, l! After soaking for 10 minutes, heat treatment and reaction with chlorine were performed in the same manner as in Example 5.

The reaction time required for the reaction rate to reach 100% was 75 minutes, and the amount of boron trichloride produced was 3'5g (300mm
ol).

Comparative Example 1 After mixing 85 g of diboron trioxide powder and 28.9 g of graphite powder that passed through 100 mesh nodes,
The pellets were press-molded into cylindrical pellets of m11t and 6 mm in height, filled into a quartz reaction tube with an inner diameter of 24 mm, and reacted with chlorine at 800° C. by flowing chlorine gas at a flow rate of 100111/mvt.

The reaction time required to reach a reaction rate of diboron trioxide of 50% was 320 minutes.

Comparative Example 2 Comparative Example 1 except that the reaction temperature with chlorine was changed to 600°C.
In the same manner as above, a molded product of boron trichloride powder and graphite powder was reacted with chlorine, but even after 240 minutes, the reaction rate of diboron trioxide was only 2%.

Comparative Example 3 A reaction with chlorine was carried out in the same manner as in Example 1, except that the heat treatment temperature and reaction temperature were changed to 200°C.
Even after 240 minutes had passed, the reaction rate was still 10%.

Comparative Example 4 8.5 g of diboron dioxide powder and 6.0 g of activated carbon powder that passed through 60 mesh nodes were mixed, and this was mixed into a tube with an inner diameter of 40 m.
Place it in a quartz flat bottom reactor with 200 m of argon gas.
ml! After heating at 400°C for 3 hours while flowing at a flow rate of /mvt, chlorine gas was added at 10
0 ml: The reaction with chlorine was carried out at 800° C. by flowing at a flow rate of 77 ml, but the reaction rate of diboron trioxide was 45% even after 35 hours.

Claims (1)

[Claims] 1. Boric acid-supported activated carbon obtained by impregnating granular activated carbon with a boric acid aqueous solution is heated to 300 to 8
A method for producing boron trichloride, which comprises heating at 00°C and then reacting with chlorine at 300 to 800°C.