JPH072526A - Exhaust gas recovery method - Google Patents

Abstract

(57) [Summary] [Structure] During the production of antimony pentachloride, the exhaust gas containing chlorine gas, antimony trichloride and antimony pentachloride discharged from the reaction can, dechlorination gas can and its ancillary equipment is supplied to a metal antimony packed column. A method for collecting exhaust gas by capturing the exhaust gas. The temperature in the packed tower of the metal antimony is 75 to 138 ° C., and the temperature in the dechlorination gas can is 40 to 138 ° C.
A method for recovering exhaust gas, characterized in that the temperature is 80 ° C. [Effect] In the method for producing antimony pentachloride according to the present invention, it becomes possible to efficiently collect chlorine gas and antimony chloride in the exhaust gas from the dechlorination gas can, and reduce the production cost of antimony pentachloride and at the same time, reduce the environment. It has become possible to prevent pollution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recovering exhaust gas in a method for producing antimony pentachloride.

This antimony pentachloride is widely used in the chemical industry, for example, as a chlorination catalyst in organic synthesis.

[0003]

2. Description of the Related Art As a method for producing antimony pentachloride, a method of passing chlorine through metallic antimony (see "11892").
Chemical Products ", p. 172, Publisher: Kagaku Nipposha, Date of issue: January 22, 1992, or by passing chlorine gas through molten antimony trichloride (The Merck Ind).
ex.Tenth Edition, p. 715, 1
983) is known.

In these methods, chlorine gas, antimony trichloride and antimony pentachloride (hereinafter abbreviated as antimony chloride) are discharged from a reaction can and a dechlorination gas can during or after the reaction of metal antimony with chlorine gas. Exhaust gas containing the gas comes out. If this exhaust gas is released into the air as it is, not only chlorine gas and antimony chloride are lost, but also environmental pollution is caused. Therefore, an efficient exhaust gas recovery method is desired.

[0005]

The object of the present invention is to solve the problems in the conventional method for producing antimony pentachloride, that is, to efficiently recover chlorine gas and antimony chloride in exhaust gas from a reaction can and a dechlorination gas can. A method is provided to reduce the production cost of antimony pentachloride and at the same time prevent environmental pollution.

[0006]

The present invention is a method for producing antimony pentachloride, wherein excess chlorine in exhaust gas discharged from a reaction can (1 in FIG. 1) and a dechlorination gas can (2 in FIG. 1) is used. This is a method in which gas and antimony chloride are guided to the metal antimony packing column 3 in FIG. 1 to recover the above components as antimony chloride. The antimony chloride is taken out as a liquid from the lower part of the filling tower and collected. The recovered antimony chloride is returned to the reaction can (1 in FIG. 1).

Further, the antimony chloride contained in a small amount in the gas discharged from the filling tower is shown in FIG.
It is recovered through the bag filter of 5 and the absorption tower of 6 of FIG.

The temperature of the metal antimony filling tower is set to 75 to 13
It is essential to keep at 8 ° C. Because 75 ℃
In the following, since the melting point of antimony trichloride (73.4 ° C.) is approached, the solution may be solidified. This is because the boiling point (140 ° C.) of antimony pentachloride approaches, and at the same time, a part of the antimony pentachloride is decomposed.

Further, in order to reduce the re-volatilization of the recovered antimony chloride, the temperature of the metal antimony packed column is set to 75-1.
It is preferable to maintain the temperature at 00 ° C.

It is essential to maintain the temperature of the dechlorination gas can at 40 to 80 ° C.

This is because the efficiency of dechlorination gas is low at 40 ° C. or lower, and conversely, the antimony chloride content in the exhaust gas is significantly high at 80 ° C. or higher.

The supply rate of the exhaust gas from the dechlorination gas can to the metal antimony filling tower is preferably 100 m / hour or less.

This is because when the feed rate exceeds 100 m / hour, the chlorine gas or antimony trichloride in the exhaust gas does not sufficiently react with metallic antimony.

As the metal antimony used in the metal antimony packing tower, it is preferable to use crushed metal antimony having a diameter of 2 to 10 mm.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0016]

Example: Dechlorination gas can maintained at 60 ° C (diameter: 9
5 mm, height: 120 mm, amount of antimony pentachloride loaded: 1.1 kg) was blown with dry air at a flow rate of 0.14 Nm ³ / hour, and the exhaust gas that came out was crushed with antimony (diameter 3-5 mm). Filling tower (diameter: 60 mm,
Height: 300 mm) at a flow rate of 50 m / hour.

The total amount of chlorine gas contained in this exhaust gas is 0.007 kg, and the total amount of antimony chloride is 0.07 kg.
It was 7 kg.

The temperature of the exhaust gas passing through the filling tower is lowered by a cooler, and then blown into a 10% potassium iodide aqueous solution to check the presence of chlorine gas, and blown into a 10% sodium carbonate aqueous solution to check the presence or absence of antimony chloride. confirmed.

The results are shown in Tables 1 and 2 below.

[0020]

[Table 1]

[0021]

[Table 2]

As is apparent from this table, according to the present invention,
It was revealed that almost all chlorine gas and antimony chloride in the exhaust gas were recovered.

[0023]

[Effect] In the method for producing antimony pentachloride according to the present invention, it becomes possible to efficiently collect chlorine gas and antimony chloride in the exhaust gas from the dechlorination gas can, which reduces the production cost of antimony pentachloride and at the same time It has become possible to prevent pollution.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an apparatus for recovering chlorine gas and antimony chloride in exhaust gas.

[Explanation of symbols]

 1 Reactor Can 2 Dechlorination Gas Can 3 Metal Antimony Filling Tower 4 Cooler 5 Bag Filter 6 Absorption Tower 7 Heating Oil

Claims (3)

[Claims] 1. A chlorine gas discharged from a reaction can, a dechlorination gas can and its auxiliary equipment during the production of antimony pentachloride,
An exhaust gas recovery method in which exhaust gas containing antimony trichloride and antimony pentachloride is introduced into a metal antimony packed column to capture and recover the exhaust gas. 2. The method for recovering exhaust gas according to claim 1, wherein the temperature inside the packed column of metallic antimony is 75 to 138 ° C.
A method for recovering exhaust gas, characterized in that 3. The method for recovering exhaust gas according to claim 1, wherein the temperature in the dechlorination gas can is 40 to 80 ° C.