JPS6075319A - Purification of gas containing bromine and/or iodine - Google Patents

Abstract

PURPOSE:To purify gas contg. bromine and/or iodine by allowing the gas to contact with beta-cyclodextrine and to include bromine and/or iodine in the gas. CONSTITUTION:Gas contg. bromine and/or iodine, for example, the gaseous chlorine contg. bromine and iodine produced in soda industry is passed through an absorption apparatus contg. soln. of beta-cyclodextrine. Bromine and iodine in the gaseous chlorine are included in the beta-cyclodextrine, thus, chlorine is purified. The amt. to be included in the beta-cyclodextrine is 1mol bromine or iodine per 1mol beta-cyclodextrine. The beta-cyclodextrine which has included bromine and/ or iodine is regenerated by the irradiation with supersonic wave or by heating, and is usable repeatedly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for purifying gas containing trace amounts of bromine and/or iodine.

Conventionally, chlorine is generally obtained by electrolysis of common salt, for example in the chlorine industry, but this chlorine gas contains some impurities.

In particular, for impurities such as bromine and/or iodine, there are two methods: a single method and a method using an absorption medium, but the former method requires a pressure freezing method, which requires large equipment and consumes a lot of energy due to compression freezing. In the latter method, chlorine gas is absorbed into a solvent such as carbon tetrachloride as a medium, separated from impurity gases, and then purified by distillation, etc. However, there is a risk that the solvent may mix into the chlorine. There is also a risk of explosion. Furthermore, since bromine and/or iodine are halogen elements like chlorine, they have the disadvantage that they are difficult to separate using conventional methods.

In view of these conventional drawbacks, the present inventors completed the present invention as a result of economizing.

That is, the present invention converts gas containing bromine and/or iodine into β-
This is a method for purifying a gas containing bromine and/or iodine, which is characterized by bringing it into contact with cyclodextrin and including bromine and/or iodine from the gas. Gas is purified by inclusion.

The β-cyclodextrin used in the present invention is.

It is a cyclic oligomer of glucobylanose produced when starch is degraded by the action of alkaline amylase. Generally, cyclodextrins are various organic compounds,
It is known that clathrate compounds are formed with noble gases, halogens, and some inorganic compounds; however, when chlorine gas is blown into a solution of α-cyclodextrin, clathrate compounds are formed, whereas β-cyclodextrin forms clathrate compounds. ) Since IJ does not form an clathrate compound with chlorine, but does form an clathrate compound with bromine and iodine, in the present invention, this property is utilized to purify a gas containing trace amounts of bromine and/or iodine. It is.

The bromine and/or iodine-containing gas targeted in the present invention is preferably a gas that is difficult to dissolve in water or a gas whose molecular diameter is slightly smaller than the inner diameter of IJ (β-cyclodegis), and a particularly preferred example is chlorine. I can give you gas. The concentration of bromine and/or iodine contained is from several tens of ppm to several hundred ppm, more specifically from 50 to 200 ppm.
Approximately ppm is appropriate.

Next, the purification means of the present invention will be described.

Dissolve β-cyclodextrin in water to prepare a saturated aqueous solution, or prepare a slurry of β-cyclodextrin and water, and add a gas containing trace amounts of bromine and/or iodine, such as chlorine gas obtained by electrolysis of common salt. The chlorine gas and β-cyclodextrin are brought into contact with each other at a predetermined temperature and flow rate, and the bromine and/or iodine in the chlorine gas is included in the β-cyclodextrin.

Water is preferred as a solvent for β-cyclodextrin, and organic solvents such as methanol and acetone are unsuitable because they do not include bromine and/or iodine.

Supply rate S of gas containing a trace amount of bromine and/or iodine to the volume V(1)K of β-cyclodextrin aqueous solution
(/ / Hr) In other words, the cavity velocity before is preferably 60 (Hr') or less. More preferably, it is around 30 (Hr'). If it exceeds 60 (Hr''), the gas velocity becomes too high, making it difficult for bromine and/or iodine to be included in β-cyclodextrin.

The residence time is preferably about 2 to 6 seconds.

Theoretically, the inclusion amount of β-cyclodextrin is 1 mole of bromine and/or iodine per 1 mole of β-cyclodextrin.

The inclusion temperature is preferably 0 to 40°C, more preferably 5 to 60°C. If the temperature exceeds 40°C, evaporation of water and the resulting scattering of β-cyclodextrin, as well as evaporation of chlorine and bromine, tend to occur. The envelope pressure is usually around normal pressure.

In the present invention, β-cyclodextrin containing bromine and/or iodine can be regenerated, and bromine and/or iodine can also be recovered. The reproduction method will be described below.

β-Cyclodextrin containing bromine and/or iodine can be regenerated by ultrasonic irradiation or heating and can be used repeatedly.

■ Regeneration method using ultrasound It is possible to regenerate β-cyclodextrin by irradiating it with ultrasound while flowing an inert gas into a solution of β-cyclodextrin that has lost its inclusion ability.

As an ultrasonic generating device, for example, an ultrasonic cleaner made by Branson Corporation with an output of 200 W, a frequency of 451 (Hz, and automatic oscillation) can be used. Nitrogen can be used as an inert gas, but any gas with a small molecular diameter can be used. Other inert gases can also be used.The temperature during regeneration is preferably 20 to 90°C;
Moreover, the higher the value, the more favorable the reproduction conditions.

(2) Regeneration method by heating β-cyclodextrin can be regenerated by heating a β-cyclodextrin solution that has lost its inclusion ability while flowing an inert gas.

For example, nitrogen can be used as the inert gas, but other inert gases can also be used as long as they have a small molecular diameter. There is no regeneration ability when the heating temperature is below 50℃, so 60~1
The temperature is preferably about 00°C.

According to the present invention, bromine and/or iodine in a gas containing trace amounts of bromine and/or iodine can be efficiently removed with simple operation and with minimum energy. It is possible to purify gas to a high degree of purity under reduced pressure.

In addition, a β-cyclodextrin solution that has lost its inclusion ability can be easily regenerated by ultrasound or heating.
It is possible to use β-cyclodextrin repeatedly.

EXAMPLES The present invention will be explained in more detail with reference to Examples and Reference Examples below.

In this example, an experimental apparatus as shown in FIG. 1 was used, which was equipped with a gas flow meter, a glass absorption bottle with an inner diameter of 55 m and a height of 180 mm containing a β-cyclodextrin solution, and a bottle containing water.

200'r of water and 8f of β-cyclodextrin were placed in the above absorption bottle. Crude chlorine gas containing 100 PPm of bromine was passed through the reactor at a rate of 61/Hr. 1~
B) The time-dependent change in the bromine concentration in the purified chlorine gas after lr is shown in Figure 2.
It was 58 ppm.

Example 2 Chlorine gas was purified in the same manner as in Example 1, except that the amount of β-cyclodextrin was changed to 4 tons.

The bromine concentration in purified chlorine gas changes over time as shown in Figure 2, and the bromine concentration after 1 to A Hr is 3.
It was 8 to 58 ppm.

Reference Example 1 (β-cyclodextrin that has lost its inclusion ability) Regeneration of IJ was carried out by irradiating it with ultrasonic waves.

A glass absorption bottle with an inner diameter of 55 cm and a height of 180 cm containing a β-cyclodextrin solution that had lost its inclusion ability was irradiated with ultrasonic waves while flowing nitrogen at 3//Hr. The results are shown in FIG.

The β-cyclodextrin regenerated by ultrasonic waves had the same clathration ability as the initial one, and the clathration ability of impurities, bromine and/or iodine did not change even after repeated regenerations.

Reference Example 2 β-cyclodextrin (β-cyclodextrin that has lost its inclusion ability) IJ was regenerated by heating.

Put β-cyclodextrin, which has lost its inclusion ability, into the same glass absorption bottle as in Reference Example 1, and add nitrogen! lt
The mixture was heated by changing the temperature while flowing at a flow rate of /Hr.

The main results are shown in Figure 4.

There is no regeneration ability at temperatures below 50℃, and temperatures between 60 and 92℃.
Now, the inclusion ability is 30% compared to the initial ability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an experimental apparatus used in Examples. Figure 2 shows Examples 1 and 2, Figure 3 shows Examples 6 and 4.
The figure is a graph showing the change over time in the amount of bromine reduced in Example 4. 1゛・β-Sea 0゛N String m-3L Patent Applicant Toagosei Chemical Industry Co., Ltd. Tsuta/Fusa

Claims (1)

[Claims] 1. A method for purifying a gas containing bromine and/or iodine, which comprises bringing the gas containing bromine and/or iodine into contact with β-cyclodextrin, and clathrating the bromine and/or iodine from the gas.