JP2812419B2 - Decomposition method of chloroformate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method comprising contacting a gas containing various concentrations of chloroformate with activated carbon or a metal oxide-based carrier material to decompose the chloroformate to form an alkyl chloride. The present invention relates to a method for decomposing and removing chloroformate. The present invention, for example,
Carbon monoxide and nitrite are reacted in the presence of a solid catalyst and under the supply of hydrogen chloride to effectively decompose and remove the chloroformate produced as a by-product in a carbonylation reaction or the like that produces a carbonate or the like, It can be applied to solve problems such as corrosion due to by-produced chloroformate.

[0002]

2. Description of the Related Art As a method of decomposing chloroformate, a method of heating chloroformate to alkyl chloride in the presence of a Lewis acid such as boron trifluoride is disclosed in J. Am.
As shown in Chem. Soc., 77, 5033 (1955), this method took a long time to decompose the chloroformate of lower alcohol and the decomposition rate was low. Also, N-
A method for producing an alkyl chloride by heating a chloroformate to 120 to 130 ° C. in an aprotic solvent such as methylpyrrolidone is disclosed in German Patent Publication No. 2545659.
However, this method is not an industrially economical method for decomposing chloroformate, for example, it is a liquid phase method using a special solvent and requires a solvent tank for that purpose.

[0003]

As described above, none of the conventionally known methods for decomposing chloroformate is economical to carry out industrially. In particular, a method for removing trace amounts of chloroformate by-produced together with generation of a target compound in a reaction gas in a chemical reaction in a chemical industry or the like by a simple means has not been practically known.

[0004]

Means for Solving the Problems In order to solve the above-mentioned problems in the conventionally known method for decomposing chloroformate, the present inventors have developed a mixed gas containing chloroformate in various ratios. As a result of intensive studies on an economical method that can efficiently decompose chloroformate in water, the chloroformate is extremely easily decomposed and converted to alkyl chloride by contacting the chloroformate with activated carbon or a metal oxide carrier material. We have found that we can do this and have completed the present invention.

That is, the present invention provides a chloroformate ester characterized in that a gas containing a chloroformate ester is brought into contact with activated carbon or a metal oxide-based carrier material to decompose the chloroformate ester to form an alkyl chloride. And a method for disassembling.

Hereinafter, the decomposition method of the present invention will be described in detail. The chloroformate used in the present invention is:
Any lower alkyl ester of chloroformate formed from chloroformic acid and an aliphatic alcohol having 1 to 4 carbon atoms may be used, such as methyl chloroformate, ethyl chloroformate, n- (or i-) propyl chloroformate, Preferred examples include lower alkyl chloroformates such as n- (or i-, sec-) butyl chloroformate. That is, the lower alkyl group in the lower alkyl chloroformate is methyl, ethyl, n-propyl, i-
Propyl, n-butyl, i-butyl, sec-butyl,
Examples thereof include an alkyl group having 1 to 4 carbon atoms such as t-butyl.

The gas containing chloroformate in the present invention may be a gas containing chloroformate at any ratio, for example, 10 pp.
A gas containing a chloroformate at a content of m to 100% by volume, more preferably 20 ppm to 50% by volume may be used. The decomposition method of the present invention is characterized in that the gas containing chloroformate is 20 to 10000 pp
m, in particular, a gas containing a chloroformate in a low content ratio of about 50 to 5000 ppm.

Further, in the present invention, in the above-mentioned gas containing chloroformate, the gas which can coexist with the chloroformate is not particularly limited. For example, the gas which can coexist is as follows:
An inert gas such as a nitrogen gas or a carbon dioxide gas can be used, and a gas such as carbon monoxide, a nitrite, an alcohol, or oxygen may be present.

The alkyl chloride produced by the method for decomposing chloroformate of the present invention includes methyl chloride, ethyl chloride, and n- (or i-chloride) corresponding to the chloroformate in the gas used first. ) Lower alkylmonochloride having 1 to 4 carbon atoms such as) propyl and n- (or i-, sec-) butyl chloride.

[0010] Most preferably, activated carbon is used to decompose chloroformate in the decomposition method of the present invention. The activated carbon is generally used as long as it can be used as a carrier, adsorbent or decolorizing agent for a reaction catalyst. The shape, size (particle size), physical properties (specific surface area, density, etc.), chemical properties (acid strength, etc.), etc. are not particularly limited, but the specific surface area of the activated carbon is 100 m ² / g. Above, especially 200 to 3000 m ² / g, and more preferably 300 to ²⁰
Granular, pellet, honeycomb and other shapes having a size of about 00 m ² / g are preferred.

As the metal oxide-based carrier substance used in the decomposition method of the present invention, generally, as long as it can be used as a carrier for a reaction catalyst, its shape, size (particle size), physical properties (specificity) Surface area, density, etc., chemical properties (acid strength, etc.) are not particularly limited, but the specific surface area is 100 m ² or more, particularly 200 to 1000 m ^2.
2 / g, and more preferably about 300 to 800 m ² / g, such as granules, pellets, and honeycombs.

Examples of the metal oxide-based support material include aluminas such as γ-alumina, α-alumina and η-alumina, silica zeolites, synthetic zeolites such as X-type, Y-type and A-type, soda-fluorite, Natural zeolites such as mordenite, molecular sieves, silica alumina,
Metal oxide-based carrier materials such as silica, titania, and zirconia are exemplified. In the present invention, as the metal oxide-based carrier material, in particular, γ-alumina, α-alumina, η
-Alumina, such as alumina, and aluminum oxide-based granular supports, such as zeolite, and activated carbon are preferred.

In the present invention, the reaction for decomposing the chloroformate into an alkyl chloride can be carried out either in a batch system or a continuous system, but a continuous gas phase reaction is industrially advantageous. At this time, the activated carbon or the metal oxide-based carrier substance may be used in any state of a fixed bed or a fluidized bed.

[0014] In the present invention, the reaction for decomposing the chloroformates to alkyl chlorides is preferably a space velocity of the gas being fed (GHSV) is 1000～30000Hr ^-1, in particular 2000～20000Hr ^-1,
Further, the temperature of the decomposition reaction is 0 to 220 ° C, particularly 10 to 200 ° C.
It is preferable to maintain the temperature in the range of about 20C to about 150C in order to further increase the conversion. Further, since this decomposition reaction does not largely depend on pressure, the decomposition reaction is performed under normal pressure or under pressure (for example, 1 to 20 kg / cm ² , preferably ² to 5 k
g / cm ² ).

In the present invention, the decomposition reactor filled with the activated carbon or the metal oxide-based carrier material is a single-tube type even if it is a multi-tube type, if the decomposition reaction does not involve relatively large heat generation. Or other shapes may be used.

The gas that has undergone the decomposition reaction as in the present invention is:
Since the chloroformate is substantially decomposed and converted to an alkyl chloride, and substantially no chloroformate remains, corrosion of the subsequent piping and the like is considerably reduced.

[0017]

EXAMPLES Next, the method of the present invention will be specifically described with reference to examples and comparative examples, but these do not limit the method of the present invention at all.

Example 1 A glass gas-phase reaction tube (with an outer jacket) having an inner diameter of 13 mm and a length of 250 mm was charged with 5 ml of granular activated carbon (Shirasagi: manufactured by Takeda Pharmaceutical Co., Ltd.) having a specific surface area of 1040 m ² / g.
The heat medium is circulated through the jacket of the reaction tube so that the temperature in the reaction layer becomes 1
The heating was controlled to 20 ° C. From the top of this reaction tube, a gas diluted with nitrogen containing 500 ppm by volume of methyl chloroformate was charged at a space velocity of 4000 hr ^-1 (GHS
V), and the reaction was carried out under normal pressure at a reaction temperature of 120 ° C. for 1 hour. Analysis of methyl chloroformate and methyl chloride in the output gas from the reactor by gas chromatography revealed no methyl chloroformate and a methyl chloride concentration of 50%.
It was 0 ppm by volume. From this, 100% of methyl chloroformate was decomposed.

Example 2 The granular activated carbon in Example 1 was changed to 1 ml of activated alumina (24-mesh pulverized product: manufactured by Kanto Kagaku), methyl chloroformate was changed to 840 ppm by volume, and gas space velocity (GHSV)
Was changed to 20000 hr ^-1 , and the reaction was carried out in the same manner as in Example 1 to analyze the product. As a result, methyl chloroformate in the reactor outlet gas could not be confirmed, and the concentration of methyl chloride was 840 ppm by volume. From this, 100% of methyl chloroformate was decomposed.

Example 3 The granular activated carbon in Example 1 was changed to 1 ml of activated alumina (24-mesh pulverized product: manufactured by Kanto Chemical), methyl chloroformate to 800 ppm by volume, gas space velocity (GHSV)
Was changed to 20,000 hr ^-1 and the reaction temperature was changed to 80 ° C., and the reaction was carried out in the same manner as in Example 1 to analyze the product.
As a result, the concentration of methyl chloroformate in the outlet gas of the reactor was 260 ppm by volume, and the concentration of methyl chloride was 540 vol.
pm. As a result, methyl chloroformate had been decomposed by 65%.

Example 4 The granular activated carbon in Example 1 was replaced with zeolite (HSZ-3).
The reaction was carried out in the same manner as in Example 1 except that the amount of methyl chloroformate was changed to 600 ppm by volume and the gas hourly space velocity (GHSV) was changed to 20,000 hr ^-1 , and the product was analyzed. As a result, the concentration of methyl chloroformate in the reactor outlet gas was 430 ppm by volume, and the concentration of methyl chloride was 1970 ppm by volume. As a result, methyl chloroformate was decomposed by 82%.

Example 5 The granular activated carbon in Example 1 was replaced with zeolite (HSZ-3).
20NAD: manufactured by Tosoh) 10 ml, methyl chloroformate to 2000 vol ppm, gas space velocity (GHS
The reaction was carried out in the same manner as in Example 1 except that V) was changed to 3000 hr ^-1 , and the product was analyzed. As a result, methyl chloroformate in the reactor outlet gas could not be confirmed, and the concentration of methyl chloride was 2000 ppm by volume. From this, 100% of methyl chloroformate was decomposed.

Example 6 The granular activated carbon in Example 1 was replaced with titania (DC314).
4, 24 mesh pulverized product: manufactured by Diamond Catalyst) Changed to 5 ml and 2,000 volumes of methyl chloroformate
pm, gas hourly space velocity (GHSV) 6000hrs
^The reaction was carried out in the same manner as in Example 1 except that the reaction temperature was changed to 150 ° C., and the product was analyzed. As a result, the concentration of methyl chloroformate in the reactor outlet gas was 800 vol.
In m, the concentration of methyl chloride was 1200 ppm by volume. As a result, methyl chloroformate was decomposed by 60%.

Example 7 The granular activated carbon in Example 1 was replaced with γ-alumina (KHA-
24: manufactured by Sumitomo Chemical Co., Ltd.) 1 ml, methyl chloroformate to 1250 ppm by volume, and gas hourly space velocity (GHSV) to 2
The reaction was carried out in the same manner as in Example 1 except that the reaction product was changed to 0000 hr ^-1 , and the product was analyzed. As a result, the concentration of methyl chloroformate in the outlet gas from the reactor was 440 ppm by volume, and the concentration of methyl chloride was 810 ppm by volume. Than this,
Methyl chloroformate was 65% degraded.

Example 8 The granular activated carbon in Example 1 was converted to a specific surface area of 1300 m ² /
g of granular activated carbon (Kureha beads: manufactured by Kureha Chemical Co., Ltd.), 5 ml, methyl chloroformate at 1000 ppm by volume, gas hourly space velocity (GHSV) at 6000 hr ^-1 and reaction temperature at 40 ° C. The reaction was carried out in the same manner as described above, and the product was analyzed. As a result, methyl chloroformate in the reactor outlet gas could not be confirmed, and the concentration of methyl chloride was 1000
The volume was ppm. Thus, methyl chloroformate is 1
It had been decomposed by 00%.

Example 9 The granular activated carbon obtained in Example 1 was converted to a specific surface area of 490 m ² / g.
Was changed to 5 ml of granular activated carbon (Morshibon: manufactured by Takeda Pharmaceutical Co., Ltd.), methyl chloroformate to 1000 ppm by volume, gas space velocity (GHSV) to 6000 hr ^-1 and reaction temperature to 2 ppm.
The reaction was carried out in the same manner as in Example 1 except that the temperature was changed to 0 ° C., and the product was analyzed. As a result, methyl chloroformate in the reactor outlet gas was not confirmed, and the concentration of methyl chloride was 1000 ppm by volume. Thus, methyl chloroformate is 10
It had been decomposed by 0%.

Example 10 The granular activated carbon obtained in Example 1 was converted to a specific surface area of 490 m ² / g.
Example 1 was changed to 1 ml of granular activated carbon (Morushibon: Takeda Pharmaceutical Co., Ltd.), the methyl chloroformate was changed to 2000 vol ppm, the gas hourly space velocity (GHSV) was changed to 30,000 hr ⁻¹ , and the reaction temperature was changed to 40 ° C. The reaction was performed in the same manner and the product was analyzed. As a result, methyl chloroformate in the reactor outgas was not confirmed, and the concentration of methyl chloride was 2,000.
The volume was ppm. Thus, methyl chloroformate is 1
It had been decomposed by 00%.

Example 11 The granular activated carbon in Example 1 was converted to a specific surface area of 490 m ² / g.
Example 1 was changed to 1 ml of granular activated carbon (Morushibon: manufactured by Takeda Pharmaceutical Co., Ltd.), the methyl chloroformate was changed to 2000 vol ppm, the gas hourly space velocity (GHSV) was changed to 30,000 hr ⁻¹ , and the reaction temperature was changed to 20 ° C. The reaction was performed in the same manner and the product was analyzed. As a result, the concentration of methyl chloroformate in the gas discharged from the reactor was 400 ppm by volume, and the concentration of methyl chloride was 1600 ppm by volume. As a result, methyl chloroformate was decomposed by 80%.

Comparative Example 1 The granular activated carbon in Example 1 was changed to glass beads (Pyrex) 10 ml, methyl chloroformate to 1000 ppm by volume, and gas hourly space velocity (GHSV) to 3000 hr.
^The reaction was carried out in the same manner as in Example 1 except that the product was changed to ^-1 , and the product was analyzed. As a result, the concentration of methyl chloroformate in the gas discharged from the reactor was 1000 ppm by volume, and no methyl chloride could be confirmed. From this, methyl chloroformate was not decomposed at all. Table 1 summarizes the results of Examples 1 to 12 and Comparative Example 1.

[0030]

[Table 1]

[0031]

According to the process of the present invention, it is possible to very easily, economically and efficiently decompose chloroformate and convert it to alkyl chloride. In particular, in the present invention, even for trace amounts of chloroformate in a gas having a low chloroformate content, the chloroformate is efficiently decomposed and converted to alkyl chloride at an extremely high rate to remove the chloroformate. can do.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B01J 21/18 B01J 21/18 X C07C 17/00 C07C 17/00 19/03 19/03 68/00 68/00 A 68/08 68 / 08 // C07B 61/00 300 C07B 61/00 300 (72) Inventor: Toshio Kurato, 1978 Kogushi, Oji, Ube City, Yamaguchi Prefecture 5 Ube Industries, Ltd. Ube Research Laboratory (72) Inventor: Masato Murakami Ube City, Yamaguchi Prefecture 1978 Ogushi Kogushi 5 Ube Industries, Ltd. Ube Research Laboratory Examiner Hiroko Fujiwara (56) References JP-A-6-329596 (JP, A) US Patent 4,814,524 (US, A) West German Patent Application Publication 2545659 (DE) , A1) (58) Fields investigated (Int. Cl. ⁶ , DB name) C07C 69/96 C07C 17/00 C07C 19/03 C07C 68/00 C07C 68/08 CA (STN)

Claims (1)

(57) [Claims] 1. A method for decomposing chloroformate, comprising contacting a gas containing chloroformate with activated carbon or a metal oxide-based carrier material to decompose the chloroformate to form an alkyl chloride.