JP2000038355A - Recovery of chlorinated saturated hydrocarbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To safely and efficiently recover a chlorinated saturated hydrocarbon by bringing a gas containing chlorinated saturated hydrocarbon into contact with a specific absorbing liquid to the chlorinated saturated hydrocarbon be absorbed in the absorbing liquid. SOLUTION: This method for recovering a chlorinated saturated hydrocarbon is performed by bringing (A) mixed gas containing (i) a vapor or a gas of preferably a 1-4C chlorinated saturated hydrocarbon (e.g. chloromethane) and (ii) at least one kind of gas selected from a vapor, a steam, a nitrogen gas and an oxygen gas into contact with (B) an absorption liquid at least one kind of (iii) a compound selected from an aromatic compound (e.g. dodecylbenzene) and a naphthene-based hydrocarbon and having >=180 deg.C, preferably >=200 deg.C, more preferably >=400 deg.C boiling point to absorb the component (i) into the component B. Preferably, a content of the component (i) in the component A is preferably >=20 vol.%. Preferably, a content of the component (iii) in the component B is preferably >=20 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for safely and efficiently recovering chlorinated saturated hydrocarbons from a gas containing chlorinated saturated hydrocarbons.

[0002]

2. Description of the Related Art As a method for recovering a chlorinated saturated hydrocarbon from a gas containing a chlorinated saturated hydrocarbon, an adsorption method, an absorption method, a condensation method and the like are known. In the adsorption method, usually, a gas containing a low concentration of chlorinated saturated hydrocarbon is brought into contact with activated carbon, and after adsorbing this, the chlorinated saturated hydrocarbon is desorbed by pressure change, temperature change, etc., and this is concentrated. Then, the chlorinated saturated hydrocarbon is recovered by cooling. The condensation method is cryogenic separation or the like in which a gas containing a chlorinated saturated hydrocarbon is cooled to a boiling point or lower to condense the chlorinated saturated hydrocarbon contained in the gas. The absorption method is a method in which, for example, water is allowed to flow down from the top of a tower as an absorbing liquid to a packed tower, and a gas containing chlorinated saturated hydrocarbon is supplied from the bottom of the tower.

[0003] The adsorption method requires large equipment,
There is a disadvantage that the operation is complicated and a large amount of energy is required, and thus economical efficiency is lacking. In addition, the condensation method has a disadvantage that it requires a large amount of energy and thus lacks economy, and when the content of the chlorinated saturated compound is low, the efficiency becomes poor. On the other hand, in the absorption method,
Water has been used as an absorbing solution, but chlorinated saturated hydrocarbons have very low solubility in water, so absorption efficiency is low,
In some cases, the equipment must be large in order to be sufficiently absorbed. Also, JP-A-52-65206 discloses that
A method is disclosed in which a specific ester compound, ketone compound, ether compound, aromatic compound, or the like is used as an absorbing solution, and a vinyl halide-containing gas is brought into contact with the absorbing solution to recover vinyl halide. However, these absorbents have problems such as low boiling point, easy evaporation, and strong odor, which may be harmful to the environment. In order to prevent vapor scattering of these absorbing liquids, additional absorbing equipment is required, which may complicate and increase the cost.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for safely and efficiently recovering a chlorinated saturated compound.

[0005]

That is, the gist of the present invention is as follows.
A gas containing a chlorinated saturated hydrocarbon, and a boiling point selected from the group consisting of an aromatic compound and a naphthenic hydrocarbon having a boiling point of 180.
The present invention relates to a method for recovering a chlorinated saturated hydrocarbon, wherein the chlorinated saturated hydrocarbon is absorbed into the absorbing solution by bringing the absorbing solution into contact with an absorbing solution containing at least one compound having a temperature of not less than ° C.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for recovering a chlorinated saturated hydrocarbon according to the present invention, the term “gas containing a chlorinated saturated hydrocarbon” refers to the vapor or gas of the chlorinated saturated hydrocarbon and the other organic compounds. A mixture containing at least one selected from the group consisting of steam, water vapor, nitrogen gas, and oxygen gas.

The content of the chlorinated saturated hydrocarbon in the gas containing the chlorinated saturated hydrocarbon is preferably 20% by volume or more, and more preferably 50% by volume, from the viewpoint of absorption efficiency.
More preferably, the content is 90% by volume or less from the viewpoint of stable operation.

The chlorinated saturated hydrocarbon is not particularly limited, but is preferably a chlorinated saturated hydrocarbon having 1 to 4 carbon atoms. For example, chloromethane, dichloromethane,
Chloroform, tetrachloromethane, chloroethane,
1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,2,3-trichloropropane, chlorobutane and the like can be mentioned.

In the method for recovering a chlorinated saturated hydrocarbon according to the present invention, a compound having a boiling point of 180 ° C. or higher selected from the group consisting of an aromatic compound and a naphthenic hydrocarbon is used as the chlorinated saturated hydrocarbon absorbing solution. There is one major feature in using solutions containing one or more. By using the absorbing liquid, it is possible to efficiently recover chlorinated saturated hydrocarbons, and to exhibit an excellent effect that costs required for equipment costs and the like can be reduced.

The boiling point of the aromatic compound and the naphthenic hydrocarbon is 180 ° C. or higher, preferably 200 ° C. or higher, from the viewpoint of suppressing the evaporation of the absorbing solution, and preferably 400 ° C., from the viewpoint of the fluidity of the absorbing solution. It is below ° C.

As the aromatic compound, derivatives such as esters or ethers obtained from alkylbenzene (having 13 to 20 carbon atoms), phthalic acid, o-, m- and p-terephthalic acid, trimellitic acid, and the like; Compounds having a boiling point of 180 ° C. or higher, such as alkylnaphthalene, alkylbiphenyl, diphenyl, diphenylether, hydrogenated triphenyl, benzyltoluene, and dibenzyltoluene, may be mentioned. The aromatic compounds may be used alone or in combination of two or more. Among the aromatic compounds, alkylbenzene having 13 to 20 carbon atoms, alkylnaphthalene, alkylbiphenyl, diphenyl, diphenylether, triphenyl hydride, benzyltoluene, and dibenzyltoluene are preferable, and particularly, carbon atoms having 16 to 20 carbon atoms.
-20 alkylbenzenes are more preferred, and dodecylbenzene is particularly preferred.

As the naphthenic hydrocarbon, for example, a cycloalkane having 4 or more carbon atoms has one or more linear or branched alkyl groups having 4 or more carbon atoms and a boiling point of 180.
Compounds at a temperature of at least ℃ are mentioned. The number of carbon atoms of the cycloalkane is preferably 4 or more from the viewpoint of the boiling point,
It is more preferably 6 or more, and preferably 10 or less from the viewpoint of fluidity. In addition, the number of carbon atoms of the linear or branched alkyl group is preferably 4 or more from the viewpoint of boiling point, and preferably 20 or less from the viewpoint of fluidity.

The aromatic compound and the naphthenic hydrocarbon may be used alone or in combination of two or more.

[0014] In the absorbing solution, the boiling point selected from the group consisting of the aromatic compound and the naphthenic hydrocarbon is 1
The content of one or more compounds at 80 ° C. or higher is preferably 20% by weight or more, more preferably 40% by weight or more, from the viewpoint of absorption efficiency.

The absorbing solution may be a uniformly dissolved solution or a heterogeneous mixed solution. Further, in the absorbing liquid,
In addition to at least one selected from the group consisting of the aromatic compounds and naphthenic hydrocarbons, water, paraffinic hydrocarbons, higher alcohols, fatty acids, inorganic substances, and the like may be optionally included.

The absorption equipment used in the method for recovering chlorinated saturated hydrocarbons of the present invention includes, for example, an absorption tower, a tank type and the like.

From the viewpoint of the solubility of the gas containing the chlorinated saturated hydrocarbon in the absorbing solution, the temperature condition in the absorption facility is preferably a low temperature condition, more preferably 0 ° C to 30 ° C. In addition, the pressure conditions in the absorption facility when performing absorption,
From the viewpoint of solubility of gas containing chlorinated saturated hydrocarbon,
0.1 MPa-0.5 MPa is more preferable.

When the chlorinated saturated hydrocarbon is recovered after absorbing the gas containing the chlorinated saturated hydrocarbon into the absorbing solution, the chlorinated saturated hydrocarbon is removed from the absorbing solution by heating or adjusting the pressure of the absorbing solution. The absorbed gas can be separated and recovered.

[0019]

EXAMPLE 1 absorption tower [inner diameter 25φ packed column, Sulzer packing (Sumitomo Heavy Industries Co., Ltd.) 25 mm × 0.5 m ^h filled] than the top, as absorption liquid, of 25 ° C. dodecylbenzene (linear Chains, a boiling point of 271 ° C. and an average molecular weight of 246) are continuously injected at a rate of 1 kg / hour, and a mixed gas of chloromethane and nitrogen [chloromethane: nitrogen] is supplied from the lower part of the absorption tower as a gas containing chlorinated saturated hydrocarbons. Gas = 1: 1 (volume ratio), measured by gas chromatography (hereinafter referred to as GC)] at a rate of 8 L / hour. The pressure inside the absorption tower was operated at normal pressure. After 30 minutes, the exhaust gas at the outlet of the absorption tower was sampled, and the concentration of chlorinated saturated hydrocarbons contained in the exhaust gas (ppm) and the concentration of dodecylbenzene as the gas concentration derived from the absorbing solution contained in the exhaust gas (GC) were measured using GC. ppm).

Example 2 The absorption liquid of Example 1 was prepared by using Essotherm 500 (manufactured by Esso Oil Co., Ltd., boiling point: 400 ° C., composition: 4% by weight of aromatic hydrocarbon, 24% by weight of naphthenic hydrocarbon, and paraffinic carbon Hydrogen 72% by weight], and the other conditions were the same as in Example 1. Using GC, the concentration (ppm) of chlorinated saturated hydrocarbons contained in the exhaust gas and the concentration of the gas derived from the absorbing solution contained in the exhaust gas The concentration (ppm) of hydrocarbons derived from the absorbing solution was measured.

Example 3 A gas containing the chlorinated saturated hydrocarbon of Example 1 was mixed with a mixed gas of dichloromethane and nitrogen [dichloromethane: nitrogen = 3: 7].
(Volume ratio)], and the other steps were the same as in Example 1.

Example 4 The procedure of Example 1 was repeated, except that the pressure in Example 1 was changed from normal pressure to 0.2 MPa.

Example 5 500 g of the same dodecylbenzene used in Example 1 was injected into a 1 L glass reactor (flask), and 1 k
After deaeration under reduced pressure to Pa, 5 L of a mixed gas of chloromethane and nitrogen [chloromethane: nitrogen = 4: 1 (volume ratio)] was injected at a temperature of 25 ° C., and the gas in the gas phase was analyzed.

Example 6 The procedure of Example 1 was repeated except that the temperature of Example 1 was changed to 5 ° C.

Example 7 A naphthenic hydrocarbon [manufactured by Showa Shell Co., Ltd., trade name: Shell Clavus Oil 32 (boiling point: 3)
20 ° C.), the content of the naphthene component being 44.5% by weight, and the balance being a paraffinic hydrocarbon]. Using GC, the concentration of chlorinated saturated hydrocarbons (ppm) contained in the exhaust gas and the concentration of hydrocarbons derived from the absorbing solution (p
pm).

Comparative Example 1 The procedure of Example 1 was repeated, except that the absorbent was replaced with n-paraffin (boiling point: 300 ° C.) using the experimental apparatus of Example 1. Using GC, the concentration of chlorinated saturated hydrocarbons (ppm) contained in the exhaust gas and the concentration of hydrocarbons derived from the absorbing solution (pp
m) was measured.

Comparative Example 2 1 kg of 25 ° C. toluene (boiling point: 110 ° C.) was introduced from the upper part of the absorption tower used in Example 1 under a pressure of 0.2 MPa.
/ Hr continuously, and a mixed gas of chlorinated saturated hydrocarbon and nitrogen [chloromethane: nitrogen = 1:
1 (volume ratio)] was continuously supplied at a rate of 8 L / hour. In the same manner as in Example 1, the chlorinated saturated hydrocarbon concentration (ppm) contained in the exhaust gas and the toluene concentration (ppm) contained in the exhaust gas were measured.

Table 1 shows the concentrations of chlorinated saturated hydrocarbons in the exhaust gas produced in Examples 1 to 7 and Comparative Examples 1 and 2.

[0029]

[Table 1]

GC measurement conditions Column used: Glass ID 3φ × 2 m DOP, 30% Uniport 60/80 Column temperature conditions: Hold at 60 ° C. for 5 minutes, heat up to 250 ° C. at a rate of 10 ° C./min, 250 ° C. For 5 minutes.

Injection temperature: 150 ° C. Detector: FID

As shown in Table 1, according to the recovery methods of Examples 1 to 7, compared with the recovery methods of Comparative Examples 1 and 2, the chlorinated saturated carbon contained in the exhaust gas generated after the recovery of the chlorinated saturated hydrocarbon was used. It shows that the amount of hydrogen can be reduced to low concentrations. Further, according to the recovery method of Comparative Example 2, although the evaporated gas derived from the absorbing solution is included in the exhaust gas,
According to the recovery method of No. 7, it is impossible to detect the vaporized gas derived from the absorption liquid in the exhaust gas. From the above results, the methods for recovering chlorinated saturated hydrocarbons of Examples 1 to 7 are excellent in recovering chlorinated saturated hydrocarbons, and can prevent a reduction in recovery efficiency due to evaporation of the absorbing solution and an increase in equipment costs and operating costs. The method is shown.

[0033]

According to the method of the present invention, there is an excellent effect that the chlorinated saturated hydrocarbon can be safely and efficiently recovered, and the equipment cost and the operating cost can be reduced.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshio Koga 1334 Minato, Wakayama-shi Kao Corporation Research Laboratory F-term (reference) 4H006 AA02 AD18 BB11 BB49

Claims (4)

[Claims] 1. A gas containing a chlorinated saturated hydrocarbon is brought into contact with an absorbing solution containing at least one compound having a boiling point of 180 ° C. or higher selected from the group consisting of aromatic compounds and naphthenic hydrocarbons. A method for recovering a chlorinated saturated hydrocarbon, wherein the chlorinated saturated hydrocarbon is absorbed in an absorbing solution. 2. The absorption liquid according to claim 1, wherein the absorbing liquid contains at least 20% by weight of one or more compounds having a boiling point of 180 ° C. or higher selected from the group consisting of aromatic compounds and naphthenic hydrocarbons. Collection method. 3. An absorbent comprising an alkylbenzene having 13 to 20 carbon atoms, an alkylnaphthalene, an alkylbiphenyl,
3. The recovery method according to claim 1, wherein the method comprises one or more compounds selected from the group consisting of biphenyl, diphenyl ether, hydrogenated triphenyl, benzyltoluene and dibenzyltoluene. 4. The recovery method according to claim 1, wherein the chlorinated saturated hydrocarbon is a chlorinated saturated hydrocarbon having 1 to 4 carbon atoms.