JP4507615B2 - Chlorine production method - Google Patents

Description

  The present invention relates to a method for producing chlorine. More specifically, the present invention relates to a method for producing chlorine by oxidizing hydrogen chloride with oxygen by a catalytic reaction in a fixed bed, and relates to a method for producing chlorine having an excellent feature that the conversion rate of hydrogen chloride is high. .

  A method for producing chlorine in which hydrogen chloride is oxidized with oxygen by catalytic reaction in a fixed bed is known. For example, Patent Document 1 discloses a method for producing chlorine by oxidizing hydrogen chloride with oxygen in the presence of a supported metal ruthenium catalyst, ruthenium oxide catalyst or ruthenium composite oxide catalyst. However, in the conventional method, there is no description about the order of supplying the raw material hydrogen chloride and oxygen.

Japanese Patent No. 3284879

  In such a situation, the problem to be solved by the present invention is a method for producing chlorine in which hydrogen chloride is oxidized with oxygen by a catalytic reaction in a fixed bed, and has a superior characteristic that the conversion rate of hydrogen chloride is high. The manufacturing method is provided.

That is, the present invention relates to a chlorine production method in which hydrogen chloride is oxidized with oxygen by catalytic reaction in a fixed bed, and the reaction is started by sequentially performing the following steps. It is.
1st process: The process of supplying water vapor | steam to the catalyst layer of this fixed bed 2nd process: The process of supplying hydrogen chloride in addition to supply of water vapor | steam after the 1st process 3rd process: Water vapor | steam after 2nd process In addition to supplying hydrogen chloride, supplying oxygen and starting the reaction

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing chlorine in which hydrogen chloride is oxidized with oxygen by a catalytic reaction in a fixed bed, and has an excellent characteristic that the conversion rate of hydrogen chloride is high.

In the present invention, in the method for producing chlorine in which hydrogen chloride is oxidized with oxygen by catalytic reaction in a fixed bed, it is necessary to start the reaction by sequentially performing the following steps. Thereby, a high conversion rate of hydrogen chloride can be obtained.
1st process: The process of supplying water vapor | steam to the catalyst layer of this fixed bed 2nd process: The process of supplying hydrogen chloride in addition to supply of water vapor | steam after the 1st process 3rd process: Water vapor | steam after 2nd process In addition to supplying hydrogen chloride, supplying oxygen and starting the reaction

  The first step of the present invention is a step of supplying water vapor to the fixed bed catalyst layer. By supplying water vapor to the catalyst layer, when the reaction is started by supplying oxygen in the third step, the temperature of the catalyst layer can be made uniform.

  The molar ratio of water vapor to hydrogen chloride is preferably 0.001 to 1.0, more preferably 0.005 to 0.5, and most preferably 0.01 to 0.2. If the molar ratio of water vapor to hydrogen chloride is too low, the temperature of the catalyst layer may not be uniform, and if the molar ratio is too high, the conversion rate of hydrogen chloride may be low. The temperature of the water vapor is preferably 50 to 400 ° C, more preferably 150 to 300 ° C. If the temperature of the water vapor is too low, corrosion of the reaction tubes and piping may occur when hydrogen chloride is supplied in the second step. If the temperature of the water vapor is too high, excessive energy is required. It may not be economical.

  The second step of the present invention is a step of supplying hydrogen chloride to the fixed bed catalyst layer. The hydrogen chloride is generated in the reaction of hydrogen and chlorine, pyrolysis reaction or combustion reaction of chlorine compounds, phosgenation reaction or chlorination reaction of organic compounds, chlorofluoroalkane production, hydrochloric acid heating, incinerator combustion, etc. Any containing hydrogen chloride can be used.

  Examples of thermal decomposition of a chlorine compound include production of vinyl chloride from 1,2-dichloroethane, production of tetrafluoroethylene from chlorodifluoromethane, and the like.

  Examples of the phosgenation reaction of an organic compound include production of isocyanate by reaction of an amine compound and phosgene, and production of carbonate ester by reaction of a hydroxy compound and phosgene.

  The chlorination reaction of organic compounds includes the production of allyl chloride by the reaction of propylene and chlorine, the production of ethyl chloride by the reaction of ethane and chlorine, the production of trichlorethylene and tetrachloroethylene by the reaction of 1,2-dichloroethane and chlorine, Examples include production of chlorobenzene by reaction of benzene and chlorine.

  The production of chlorofluoroalkanes includes the production of dichlorodifluoromethane and trichloromonofluoromethane by the reaction of carbon tetrachloride and hydrogen fluoride, and the production of dichlorodifluoromethane and trichloromonofluoromethane by the reaction of methane, chlorine and hydrogen fluoride. Manufacturing etc. are mentioned.

  The third step of the present invention is a step of starting the reaction by supplying oxygen in addition to supplying the water vapor and hydrogen chloride. As the oxygen, oxygen or air can be used. Further, a gas containing unreacted oxygen separated from chlorine generated by oxidizing hydrogen chloride with oxygen can be used as a part of the oxygen.

  The molar ratio of oxygen to hydrogen chloride is preferably 0.25 to 2, more preferably 0.25 to 1.5, and most preferably 0.25 to 1. If the molar ratio of oxygen to hydrogen chloride is too small, the conversion rate of hydrogen chloride may be low. On the other hand, if the molar ratio is excessive, separation of generated chlorine and unreacted oxygen may be difficult. .

  A catalyst containing ruthenium oxide, preferably a catalyst containing ruthenium oxide and titanium oxide, is used as a catalyst for the reaction of oxidizing hydrogen chloride with oxygen to produce chlorine. Catalysts containing ruthenium oxide are described in, for example, Japanese Patent No. 3284879, Japanese Patent Application Laid-Open No. 10-338502, and Japanese Patent Application Laid-Open No. 2002-292279. Catalysts containing ruthenium oxide and titanium oxide are described in, for example, JP 2000-229239 A, JP 2000-281314 A, and JP 2002-79093 A.

  Examples of the reaction method for producing chlorine by oxidizing hydrogen chloride with oxygen include, for example, JP 2000-34105 A, JP 2000-272906 A, JP 2000-272907 A, and JP 2001-199710 A. It is described in the publication.

  In the present invention, it is preferable to supply a gas containing nitrogen and / or oxygen to the catalyst layer before the start of the first step because the temperature of the catalyst layer can be made uniform. The supply of the gas containing nitrogen and / or oxygen is performed before the start of the first step, or before the start of the second step, before the start of the third step, or after the supply of oxygen in the third step. You may stop.

  In this invention, it is preferable that the catalyst bed temperature of the fixed bed of a 1st process is 0-400 degreeC, More preferably, it is 200-400 degreeC. If the catalyst layer temperature is too low, corrosion of reaction tubes and piping may occur when hydrogen chloride is supplied in the second step. If the catalyst layer temperature is too high, excessive energy is required. It may not be economical. The catalyst layer temperature before the start of the second step and the third step is preferably maintained at 200 to 400 ° C. If the catalyst layer temperature is too low, the conversion rate of hydrogen chloride may decrease when the reaction is started by supplying oxygen in the third step. On the other hand, if the reaction temperature is too high, the catalyst component volatilizes. There is.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.
Example 1
Based on the method described in JP-A-2002-79093, a 2.0% by mass ruthenium oxide granular catalyst carrying titanium oxide-α alumina having a diameter of 3 mm was prepared. The weight ratio of titanium oxide and α-alumina was 37:63. 1.0 g of the obtained titanium oxide-α-alumina-supported ruthenium oxide catalyst was filled in a nickel reaction tube (inner diameter 13 mm, outer diameter 3.2 mm sheath tube for temperature measurement) to obtain a fixed bed catalyst layer. Furthermore, 12 g of α-alumina sphere (Nikkato Co., Ltd., SSA995) was filled as the preheating layer on the catalyst layer. Further, a Teflon (registered trademark) container filled with water was installed on the inlet side of the reaction tube, and connected by a Teflon (registered trademark) pipe (inner diameter: 4 mm).

First step: The internal temperature of the container was raised to 51 ° C., and nitrogen 16 ml / min (0 ° C., converted to 1 atm) was bubbled through the water in the container and circulated. In a salt bath using molten salt (potassium nitrate / sodium nitrite = 1/1 mass ratio) as a heat medium while supplying nitrogen and water vapor from the container outlet to the catalyst layer via a pipe heated to 150 ° C. The reaction tube was immersed, and the temperature of the catalyst layer was heated to 253 to 254 ° C. and held. Subsequently, the pressure at the inlet of the reaction tube was increased to 0.5 MPaG. Furthermore, the internal temperature of the container was raised to 92 ° C., and the supply of nitrogen and water vapor was continued.
Second step: In addition to supplying nitrogen and water vapor, 80 ml / min of hydrogen chloride (0 ° C., converted to 1 atm) was supplied. The molar ratio of supplied steam to hydrogen chloride was 0.025. Five hours after the start of the supply of hydrogen chloride, the catalyst layer was heated to 281 to 282 ° C., and further kept for 20 minutes.
Third step: In addition to the supply of nitrogen, water vapor and hydrogen chloride, oxygen 40 ml / min (0 ° C., converted to 1 atm) was supplied to initiate the reaction. At 1.5 hours after the start of the reaction by the supply of hydrogen chloride, sampling was performed by circulating the gas at the outlet of the reaction tube through a 30 wt% aqueous potassium iodide solution, and chlorine was obtained by iodine titration method and neutralization titration method, respectively. And the amount of unreacted hydrogen chloride were measured. At this time, the temperature of the catalyst layer was 281 to 282 ° C. as a result of the reaction heat being removed by the molten salt.
The conversion rate of hydrogen chloride calculated by the following formula from the amount of chlorine produced was 8.1%.
Hydrogen chloride conversion rate (%) = (chlorine production (mol / min) × 2 / hydrogen chloride supply (mol / min)) × 100

Claims (1)

In the manufacturing method of chlorine which oxidizes hydrogen chloride with oxygen by the catalytic reaction of a fixed bed, the reaction is started by performing the following steps in order, and the manufacturing method of chlorine characterized by the above-mentioned.
1st process: The process of supplying water vapor | steam to the catalyst layer of this fixed bed 2nd process: The process of supplying hydrogen chloride in addition to supply of water vapor | steam after the 1st process 3rd process: Water vapor | steam after 2nd process In addition to supplying hydrogen chloride, supplying oxygen and starting the reaction