JP2012091977A - Method for producing chlorine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing chlorine useful as a raw material for e.g., vinyl chloride or phosgene by satisfactorily oxidizing an organochlorine compound.SOLUTION: Chlorine is produced by oxidizing an organochlorine compound in a mixed gas containing the organochlorine compound and oxygen and not containing hydrogen chloride or hydrogen with oxygen in the presence of a ruthenium catalyst to oxidize the organochlorine compound. As the ruthenium catalyst, a supported ruthenium oxide catalyst composed of at least one member selected from the group consisting of titanium oxide and alumina and ruthenium oxide supported thereon is desirable.

Description

  The present invention relates to a method for producing chlorine in which an organic chlorine compound in a mixed gas containing an organic chlorine compound and oxygen and not containing hydrogen chloride and hydrogen is oxidized with oxygen in the presence of a ruthenium catalyst.

  Organochlorine compounds are widely used in the chemical industry as organic solvents and raw materials for producing various organic compounds. Organochlorine compounds discharged after use are conventionally known to be decomposed by incineration, etc., but they may contain hydrogen chloride produced as a by-product due to reaction or decomposition during the use of organochlorine compounds. In order to prevent corrosion and wear of the equipment at the time, it is known that the decomposition treatment is performed after removing hydrogen chloride from the organic chlorine compound discharged after use. As a method for treating an organic chlorine compound that does not contain hydrogen chloride, for example, in Patent Document 1, an alkali metal compound is allowed to coexist in a combustion flame, and an organic chlorine compound gas that does not contain hydrogen chloride is supplied. A method for decomposing organochlorine compounds has been proposed.

JP 2001-328950 A

  In recent years, effective use of organochlorine compounds discharged after use has been desired from the viewpoints of environmental problems and processing costs. However, the conventional method has a problem that the organic chlorine compound cannot be effectively recycled. Accordingly, an object of the present invention is to provide a method for producing chlorine useful as a raw material for vinyl chloride, phosgene and the like by satisfactorily oxidizing an organic chlorine compound.

  As a result of intensive studies, the present inventor has found that an organic chlorine compound is oxidized by oxidizing an organic chlorine compound in a mixed gas containing an organic chlorine compound and oxygen and not containing hydrogen chloride and hydrogen with oxygen in the presence of a ruthenium catalyst. The present inventors have found a new finding that chlorine can be produced by satisfactorily oxidizing a compound, and the present invention has been completed.

That is, the chlorine production method of the present invention has the following configuration.
(1) A method for producing chlorine in which an organic chlorine compound in a mixed gas containing an organic chlorine compound and oxygen and not containing hydrogen chloride and hydrogen is oxidized with oxygen in the presence of a ruthenium catalyst.
(2) The production method according to (1), wherein the ruthenium catalyst is a ruthenium catalyst supported on a carrier.
(3) The production method according to (1), wherein the ruthenium catalyst is a supported ruthenium oxide catalyst in which ruthenium oxide is supported on a carrier.
(4) The production method according to any one of (1) to (3), wherein the carrier is at least one selected from the group consisting of titanium oxide and alumina.
(5) The production method according to any one of (1) to (4), wherein the organic chlorine compound is at least one selected from the group consisting of carbon tetrachloride, tetrachloroethylene, and hexachloroethane.
(6) The manufacturing method in any one of said (1)-(5) whose content rate of the organochlorine compound in the said mixed gas is 1 volume% or more.

  According to the present invention, chlorine can be produced by satisfactorily oxidizing an organic chlorine compound in a mixed gas containing an organic chlorine compound and oxygen and not containing hydrogen chloride and hydrogen with oxygen.

Hereinafter, the present invention will be described in detail. The ruthenium catalyst in the present invention may be a catalyst consisting essentially of metal ruthenium or a catalyst consisting solely of a ruthenium compound, or a catalyst consisting of a mixture of metal ruthenium and a ruthenium compound, or a carrier. A supported ruthenium catalyst in which at least one selected from the group consisting of metal ruthenium and a ruthenium compound (hereinafter sometimes referred to as “ruthenium component”) may be supported, but a supported ruthenium catalyst is preferable. Examples of the ruthenium compound include ruthenium oxide; ruthenium halides such as RuCl ₃ and RuBr ₃ , among which ruthenium oxide is preferable. Among the supported ruthenium catalysts, a supported ruthenium oxide catalyst in which ruthenium oxide is supported on a carrier is preferable. Examples of the carrier include γ-alumina, α-alumina, rutile titania (titania having a rutile crystal structure), anatase titania (titania having an anatase crystal structure), silica, zirconia, niobium oxide, activated carbon, and the like. And two or more of them can be used as necessary. Among them, at least one selected from the group consisting of γ-alumina, α-alumina, rutile type titania and anatase type titania is preferable, and at least one type selected from the group consisting of α-alumina and rutile type titania is more preferable. Further, as the ruthenium catalyst, a composite oxide of ruthenium oxide and an oxide other than ruthenium oxide such as γ-alumina, α-alumina, rutile type titania, anatase type titania, silica, zirconia, niobium oxide, etc. You can also.

Examples of the raw material ruthenium compound used as a raw material for the ruthenium catalyst in the present invention include halides such as RuCl ₃ and RuBr ₃ , halogenoacid salts such as K ₃ RuCl ₆ and K ₂ RuCl ₆ , and oxoacids such as K ₂ RuO _4. Salts, oxyhalides such as Ru ₂ OCl ₄ , Ru ₂ OCl ₅ , Ru ₂ OCl ₆ , K ₂ [RuCl ₅ (H ₂ O) ₄ ], [RuCl ₂ (H ₂ O) ₄ ] Cl, K ₂ [ Halogeno complexes such as Ru ₂ OCl ₁₀ ], Cs ₂ [Ru ₂ OCl ₄ ], [Ru (NH ₃ ) ₅ H ₂ O] Cl ₂ , [Ru (NH 3) ₅ Cl] Cl ₂ , [Ru (NH ₃ ) _{6] Cl 2, [Ru (} NH 3) 6] Cl 3, [Ru (NH 3) 6] such ammine complex of _{Br 3, Ru (CO) 5} , Ru 3 (CO) 12 of the Can carbonyl _{complex, [Ru 3 O (OCOCH 3} ) 6 (H 2 O) 3] OCOCH 3, [Ru 2 (OCOR) 4] Cl (R = alkyl group having 1 to 3 carbon atoms) such as carboxylato complexes, K ₂ [RuCl ₅ (NO)], [Ru (NH ₃ ) ₅ (NO)] Cl ₃ , [Ru (OH) (NH ₃ ) ₄ (NO)] (NO ₃ ) ₂ , [Ru (NO)] Nitrosyl complexes such as (NO ₃ ) ₃ , phosphine complexes, amine complexes, acetylacetonato complexes and the like. Of these, halides are preferably used, and chlorides are particularly preferably used. In addition, as a ruthenium compound, the hydrate may be used as needed, and those 2 or more types may be used.

  The supported ruthenium catalyst in the present invention can be obtained, for example, by supporting a raw material ruthenium compound on a carrier and then calcining in an oxidizing gas, reducing gas or inert gas atmosphere.

  In the preparation of the supported ruthenium catalyst, as a method of supporting the raw material ruthenium compound on the support, a method of impregnating the support with a solution obtained by dissolving the compound in an appropriate solvent, or immersing the support in the solution, Examples include a method of adsorbing the compound.

  When impregnating or dipping as described above, the temperature is usually 0 to 100 ° C., preferably 0 to 50 ° C., and the pressure is usually 0.1 to 1 MPa, preferably atmospheric pressure. Further, such impregnation or immersion can be performed in an air atmosphere or an inert gas atmosphere such as nitrogen, helium, argon, oxygen dioxide, and may contain water vapor. From the viewpoint of handling, it is preferable to carry out in the inert gas atmosphere.

  The oxidizing gas is a gas containing an oxidizing substance, and examples thereof include an oxygen-containing gas. The oxygen concentration is usually about 1 to 30% by volume. As the oxygen source, air or pure oxygen is usually used, and diluted with an inert gas or water vapor as necessary. Of these, air is preferable as the oxidizing gas. Moreover, a calcination temperature is 100-1000 degreeC normally, Preferably it is 250-450 degreeC.

  The reducing gas is a gas containing a reducing substance, and examples thereof include a hydrogen-containing gas, a carbon monoxide-containing gas, and a hydrocarbon-containing gas. The concentration is usually about 1 to 30% by volume, and the concentration is adjusted with, for example, an inert gas or water vapor. Among them, the reducing gas is preferably a hydrogen-containing gas or a carbon monoxide-containing gas. Moreover, a calcination temperature is 100-1000 degreeC normally, Preferably it is 200-500 degreeC.

  Examples of the inert gas include nitrogen, carbon dioxide, helium, argon, and the like, and diluted with water vapor as necessary. Among these, nitrogen and carbon dioxide are preferable as the inert gas. The firing temperature when firing in an inert gas atmosphere is usually 100 to 1000 ° C, preferably 200 to 600 ° C.

  In the supported ruthenium catalyst, the content ratio (ruthenium component / support) selected from the group consisting of metal ruthenium and a ruthenium compound with respect to the support is usually 0.1 / 99.9 to 20/80, preferably as a weight ratio. Is 0.5 / 99.5 to 15/85, and the use ratio of the raw material ruthenium compound and the carrier is appropriately adjusted so as to be in this range. If the ruthenium component is too small, the catalytic activity may not be sufficient, and if it is too much, the cost is disadvantageous.

The supported ruthenium catalyst has a BET specific surface area of usually 1 to 300 m ² / g, preferably 5 to 50 m ² / g. If the BET specific surface area is too large, the carrier and ruthenium component in the resulting catalyst are likely to sinter and thermal stability may be lowered. On the other hand, if the BET specific surface area is too small, the ruthenium component in the resulting catalyst is difficult to disperse and the catalyst activity may be lowered. The BET specific surface area is a value obtained by measurement using a specific surface area measuring device based on a nitrogen adsorption method.

  The pore volume of the supported ruthenium catalyst is usually 0.05 to 1.5 ml / g, preferably 0.1 to 1.0 ml / g. If the pore volume is too small, the pore diameter is too small, and the activity may be low. On the other hand, if the pore volume is too large, the strength of the catalyst may be reduced, which may hinder stable production of chlorine. The pore volume is a value obtained by measurement by the Hg intrusion method.

  Examples of the shape of the ruthenium catalyst used in the present invention include a spherical granular shape, a cylindrical shape, a triangular prism shape, a quadrangular prism shape, a polygonal column shape, a ring shape, and a granule having an appropriate size that is pulverized and classified after molding. . Normally, molded products such as cylindrical, triangular, quadrangular, polygonal, and ring shapes are often extruded or tableted, but in the case of extrusion, the extrudate is crushed to an appropriate length. And / or cut and used. For the purpose of reducing the amount of pulverization, the crushed and / or cut compact can be rounded using a rotating device or the like for the crushing surface or the acute angle portion of the cutting surface. At this time, the catalyst diameter is preferably 5 mm or less. When the catalyst diameter exceeds 5 mm, the activity may be lowered. The lower limit of the catalyst diameter is not particularly limited, but if it becomes too small, the pressure loss in the packed bed increases, so that the catalyst diameter is preferably 0.5 mm or more. The catalyst diameter is the average diameter of a sphere in the case of spherical particles, the average diameter of a cross section in the case of a cylindrical shape, the average maximum diameter of a cross section in the case of a molded product such as a triangular prism shape, a quadrangular prism shape, a polygonal prism shape, or a ring shape. In the case of a granulated particle having an appropriate size, it means the average value of the upper and lower aperture diameters used for classification.

  In addition, when using a ruthenium catalyst, it can also be used by diluting with titania, alumina, zirconia, silica or the like.

  In the presence of the ruthenium catalyst thus obtained, chlorine is efficiently produced by oxidizing an organic chlorine compound in a mixed gas containing an organic chlorine compound and oxygen and not containing hydrogen chloride and hydrogen with oxygen. Can do.

  Examples of the organic chlorine compound include chlorinated methane such as chloromethane, methylene chloride, chloroform, and carbon tetrachloride, chloroethane such as chloroethane, dichloroethane, trichloroethane, tetrachloroethane, pentachloroethane, and hexachloroethane, chloroethylene, dichloroethylene, Examples thereof include chlorinated ethylene such as trichlorethylene and tetrachloroethylene, and two or more thereof may be used. Of these, carbon tetrachloride, tetrachloroethylene, and hexachloroethane are preferable, and carbon tetrachloride is more preferable because water is not contained in the oxidized product and chlorine can be efficiently produced. The organochlorine compound may contain different types of organochlorine compounds that are by-produced during the production thereof. For example, in the case of an organochlorine compound such as chloromethane, methylene chloride, chloroform, and tetrachloroethylene, the organochlorine compound is produced as a by-product. The thing containing the carbon tetrachloride to produce | generate may be used. However, hydrogen chloride by-produced together with carbon tetrachloride is removed by, for example, absorbing it in water and collecting it as hydrochloric acid.

  The content ratio of the organic chlorine compound in the mixed gas is preferably 1% by volume or more, more preferably 1 to 50% by volume, and still more preferably 10 to 40% by volume. If the content ratio of the organic chlorine compound in the mixed gas is too low, the recovery efficiency of the generated chlorine may be reduced, and if it is too high, the reaction efficiency may be reduced. The mixed gas may contain an inert gas such as nitrogen gas or argon gas, and the content ratio of the organic chlorine compound in the mixed gas can be adjusted by the inert gas.

  As an oxygen source of oxygen in the mixed gas, air may be used or pure oxygen may be used. For example, when the organic chlorine compound is chlorinated methane, chlorinated ethane, or chlorinated ethylene, the content ratio of oxygen with respect to 1 mol of the organic chlorine compound in the mixed gas is, in order to completely oxidize these to chlorine, Theoretically, 1 to 2 moles of oxygen for 1 mole of chlorinated methane, 2 to 3.5 moles of oxygen for 1 mole of chlorinated ethane, and 2 to 3 moles of oxygen for 1 mole of chlorinated ethylene. Although necessary, it is preferable that 0.1 to 10 times as much oxygen as the theoretical amount of oxygen in the oxidation reaction of the organic chlorine compound to chlorine is included.

  The mixed gas does not contain hydrogen chloride and hydrogen. By not containing hydrogen chloride, it is possible to prevent corrosion and wear of the equipment during the oxidation reaction. By not containing hydrogen, the oxidation reaction can be continued stably. In addition, in the said mixed gas, what does not contain hydrogen chloride and hydrogen means that the content rate of hydrogen chloride and hydrogen in mixed gas is 0.1 volume% or less, respectively.

  200-500 degreeC is preferable and the reaction temperature in oxidation has more preferable 250-400 degreeC. If the reaction temperature is too low, a sufficient reaction rate may not be obtained. If the reaction temperature is too high, it is disadvantageous in terms of corrosion of the reactor.

  The reaction pressure in oxidation is an absolute pressure, preferably 0.1 to 5 MPa, and more preferably 0.1 to 0.5 MPa.

As a reaction method in oxidation, various methods such as a fixed bed method, a fluidized bed method, and a moving bed method can be adopted, and a fixed bed method is preferable. When the reaction is carried out in a fixed bed system, the supply rate of the organic chlorine compound is usually represented by the volume supply rate (0 ° C., 0.1 MPa conversion) of the organic chlorine compound gas per volume of the catalyst layer, that is, GHSV. It is about 10-20000h- ¹ .

  As mentioned above, although preferred embodiment concerning this invention was shown, it cannot be overemphasized that this invention is applicable to what was changed and improved in the range which is not limited to embodiment mentioned above and does not deviate from the summary of this invention. .

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited only to a following example. In the following examples, the part representing the content or amount used is based on weight unless otherwise specified. In the following examples, the gas supply rate (ml / min) is a converted value of 0 ° C. and 0.1 MPa unless otherwise specified.

  Examples of the present invention will be shown below, but the present invention is not limited thereto.

Example 1
(Catalyst preparation)
50 parts by mass of titania powder [STR-60R manufactured by Sakai Chemical Industry Co., Ltd., rutile-type titania ratio 100%] and 50 parts by mass of α-alumina powder [AES-12 manufactured by Sumitomo Chemical Co., Ltd.] Next, 12.8 parts by mass of titania sol [CSB manufactured by Sakai Chemical Co., Ltd., titania content 39%] and pure water were added and kneaded. This mixture was extruded into a cylindrical shape having a diameter of 1.5 mmφ, dried at 60 ° C. for 4 hours, and then crushed to a length of about 2 to 4 mm. The obtained molded body was heated from room temperature to 650 ° C. in air over 1.8 hours, and then calcined by holding at 650 to 680 ° C. for 3 hours, comprising a mixture of titanium oxide and α-alumina. A white carrier (rutile-type titania ratio of 50% or more, specific surface area: 20 m ² / g) was obtained.
An aqueous solution prepared by dissolving 7.91 parts by mass of ruthenium chloride hydrate (RuCl ₃ · nH ₂ O manufactured by NE Chemcat Co., Ltd., Ru content 40.0% by weight) in pure water was obtained above. 100 parts by mass of the carrier was impregnated and dried at 25 ° C. for 7 hours or more in an air atmosphere to obtain a brown solid. The obtained solid was heated from room temperature to 250 ° C. over 1.3 hours under air flow, then calcined by holding at the same temperature for 2 hours, and the supported ruthenium oxide content was 4 mass%. Ruthenium was obtained.

(Activity evaluation)
1 g of the supported ruthenium oxide obtained above was filled in a quartz reaction tube (inner diameter: 14 mm) in which a thermocouple protective tube having an inner diameter of 14 mmφ and an outer diameter of 4 mmφ was placed. In this, carbon tetrachloride gas was supplied from the reaction tube inlet at a rate of 50 Nml / min, nitrogen gas at 333 Nml / min, and oxygen gas at a rate of 80 Nml / min under normal pressure, and the hot spot temperature of the catalyst layer was 227 ° C. The reaction was started under the following conditions. At 55 minutes after the start of the reaction, sampling was performed for 10 minutes by flowing the gas at the outlet of the reaction tube through a 30% by mass aqueous potassium iodide solution, the amount of chlorine produced was measured by iodine titration, and the chlorine production rate ( mol / h). The conversion rate of carbon tetrachloride was calculated from the following formula from the chlorine generation rate and the above-mentioned carbon tetrachloride supply rate.

  Carbon tetrachloride conversion (%) = [chlorine production rate (mol / h) ÷ 2 ÷ carbon tetrachloride supply rate (mol / h)] × 100

Example 2
(Catalyst preparation)
A supported ruthenium oxide was prepared in the same manner as in Example 1.
(Activity evaluation)
1 g of the supported ruthenium oxide obtained above was filled in a quartz reaction tube (inner diameter: 14 mm) in which a thermocouple protective tube having an inner diameter of 14 mmφ and an outer diameter of 4 mmφ was placed. In this, carbon tetrachloride gas was supplied from the reaction tube inlet at a rate of 50 Nml / min, nitrogen gas at 333 Nml / min, and oxygen gas at a rate of 80 Nml / min under normal pressure, and the hot spot temperature of the catalyst layer was 245 ° C. The reaction was started under the following conditions. At 35 minutes after the start of the reaction, sampling was performed for 10 minutes by passing the gas at the outlet of the reaction tube through a 30% by mass aqueous potassium iodide solution, and the conversion rate of carbon tetrachloride was calculated in the same manner as in Example 1. The results are shown in Table 1.

Example 3
(Catalyst preparation)
A supported ruthenium oxide was prepared in the same manner as in Example 1.
(Activity evaluation)
1 g of the supported ruthenium oxide obtained above was filled in a quartz reaction tube (inner diameter: 14 mm) in which a thermocouple protective tube having an inner diameter of 14 mmφ and an outer diameter of 4 mmφ was placed. In this, carbon tetrachloride gas was supplied from the reaction tube inlet at a rate of 58 Nml / min, nitrogen gas at 333 Nml / min, and oxygen gas at a rate of 80 Nml / min under normal pressure, and the hot spot temperature of the catalyst layer was 267 ° C. The reaction was started under the following conditions. At 70 minutes after the start of the reaction, sampling was performed for 10 minutes by circulating the gas at the outlet of the reaction tube through a 30% by mass aqueous potassium iodide solution, and the conversion rate of carbon tetrachloride was calculated in the same manner as in Example 1. The results are shown in Table 1.

Example 4
(Catalyst preparation)
A supported ruthenium oxide was prepared in the same manner as in Example 1.
(Activity evaluation)
2 g of the supported ruthenium oxide obtained above was filled in a quartz reaction tube (inner diameter 14 mm) in which a thermocouple protective tube having an inner diameter of 14 mmφ and an outer diameter of 4 mmφ was placed. In this, carbon tetrachloride gas was supplied from the inlet of the reaction tube at a rate of 14.2 Nml / min, nitrogen gas was 83.5 Nml / min, and oxygen gas was supplied at a pressure of 20 Nml / min under normal pressure, and the hot spot temperature of the catalyst layer Started the reaction at 365 ° C. At 120 minutes after the start of the reaction, sampling was performed for 10 minutes by flowing the gas at the outlet of the reaction tube through a 30% by mass aqueous potassium iodide solution, and the conversion rate of carbon tetrachloride was calculated in the same manner as in Example 1. The results are shown in Table 1.

Claims (6)

  A method for producing chlorine, comprising oxidizing an organic chlorine compound in a mixed gas containing an organic chlorine compound and oxygen and not containing hydrogen chloride and hydrogen in the presence of a ruthenium catalyst with oxygen.   The production method according to claim 1, wherein the ruthenium catalyst is a supported ruthenium catalyst in which at least one selected from the group consisting of metal ruthenium and a ruthenium compound is supported on a support.   The production method according to claim 1, wherein the ruthenium catalyst is a supported ruthenium oxide catalyst in which ruthenium oxide is supported on a carrier.   The manufacturing method according to claim 1, wherein the carrier is at least one selected from the group consisting of titania and alumina.   The manufacturing method according to any one of claims 1 to 4, wherein the organic chlorine compound is at least one selected from the group consisting of carbon tetrachloride, tetrachloroethylene, and hexachloroethane.   The production method according to claim 1, wherein a content ratio of the organic chlorine compound in the mixed gas is 1% by volume or more.