JP4285179B2 - Method for producing a catalyst for chlorine production - Google Patents

Description

  The present invention relates to a method for producing a catalyst for producing chlorine. Specifically, the present invention relates to a method for producing a catalyst in which an alkali metal compound used in producing chlorine by oxidizing hydrogen chloride with oxygen and a ruthenium compound containing ruthenium oxide are supported on a carrier.

  Several proposals have been made regarding a catalyst for producing chlorine by catalytic oxidation of hydrogen chloride with oxygen. For example, Patent Document 1 discloses a catalyst in which a ruthenium compound is supported on a carrier and a supported ruthenium oxide catalyst obtained by oxidizing them. Each of the supported ruthenium oxide catalysts obtained in this manner has been proposed. In Patent Document 3, in order to atomize ruthenium oxide, which is an active species, to make a highly active catalyst, the supported metal ruthenium is calcined in the presence of an alkali metal salt in a gas containing oxygen to carry the supported ruthenium oxide. A method for producing a catalyst has been proposed. Patent Document 4 proposes a method for controlling the calcination temperature of the carrier as a method for reducing the decrease in the activity of the catalyst during the reaction.

JP-A-10-194705 JP 2000-281314 A JP 10-338502 A JP 2002-79093 A

However, these catalysts have a large decrease in activity over time during the reaction, and from an industrial standpoint, it has been desired to develop a catalyst with a smaller decrease in activity.
An object of the present invention is to provide a method for producing a catalyst having a small decrease in catalytic activity during the reaction in a method for producing a catalyst used for producing chlorine from hydrogen chloride.

  That is, the present invention relates to a method for producing a catalyst in which an alkali metal compound and a ruthenium compound containing ruthenium oxide are supported on a carrier, which is used when producing chlorine by oxidizing hydrogen chloride with oxygen, The present invention relates to a method for producing a catalyst for producing chlorine, characterized in that an alkali metal compound is added after preparing a catalyst on which a ruthenium compound containing is supported.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing a catalyst having a feature that a decrease in catalytic activity during the reaction is small in a method for producing a catalyst used for producing chlorine from hydrogen chloride.

  Hereinafter, the present invention will be described in detail. A feature of the present invention is that after a ruthenium compound containing ruthenium oxide is supported on a support, an alkali metal compound is added to form a catalyst.

  As the carrier, known carriers such as titanium oxide, aluminum oxide, zirconium oxide, silicon dioxide are used. Two or more composites can also be used. A preferred carrier is titanium oxide.

When preparing a catalyst on which a ruthenium compound containing ruthenium oxide is supported, examples of the ruthenium compound supported on the carrier include ruthenium chlorides such as RuCl ₃ and RuCl ₃ hydrate, Ru ₂ OCl ₄ , Ru ₂ OCl ₅ , Ru. Ruthenium oxychlorides such as ₂ OCl ₆ , ruthenium ammine complexes such as [Ru (NH ₃ ) ₆ ] 2+, [Ru (NH ₃ ) ₆ ] 3 +, [Ru (NH ₃ ) 5 H ₂ O] 2+, Chlorination of ruthenium ammine complexes such as [Ru (NH ₃ ) ₅ Cl] 2+, [Ru (NH ₃ ) ₆ ] Cl 2, [Ru (NH ₃ ) ₆ ] Cl ₃ , [Ru (NH ₃ ) ₆ ] Br ₃ things, bromide, RuBr _3, RuBr ₃ ruthenium bromide such as hydrates, other ruthenium organic amine complex, ruthenium acetylacetonato complex, Ru (CO) _5, ruthenium carbonitrile such Ru ₃ (CO) ₁₂ Le _{complex, [Ru 3 O (OCOCH 3} ) 6 (H 2 O) 3] OCOCH 3 hydrate, ruthenium organic acid salt such as _{Ru 2 (RCOO) 4 Cl (} R = alkyl group of 1-3 carbon atoms) Ruthenium nitrosyl complexes such as [Ru (NH ₃ ) ₅ (NO)] Cl ₃ , [Ru (OH) (NH ₃ ) ₄ (NO)] (NO ₃ ) ₂ , Ru (NO) (NO ₃ ) ₃ , And compounds such as a ruthenium phosphine complex. Preferred ruthenium compounds include ruthenium halide compounds such as ruthenium chlorides such as RuCl ₃ and RuCl ₃ hydrates, and ruthenium bromides such as RuBr ₃ and RuBr ₃ hydrates. More preferred is ruthenium chloride hydrate.

  Examples of the method for supporting the ruthenium compound on the carrier include known methods as described in JP-A-2002-79093.

  Next, examples of a method for oxidizing the supported ruthenium compound include known methods as described in JP-A-2002-79093. At this time, all of the supported ruthenium compound may be changed to ruthenium oxide, or a partially supported ruthenium compound may remain.

  The mass ratio between ruthenium oxide and the carrier is generally in the range as described in JP-A-2002-79093.

  Examples of the alkali metal compound added to the catalyst on which the ruthenium compound containing ruthenium oxide is supported include potassium chloride, sodium hydroxide, cesium nitrate, and the like, and potassium chloride is preferable.

  The amount of the alkali metal compound to be added is 0.01 to 100% by weight, preferably 0.1 to 10% by weight, based on ruthenium oxide.

  The method of adding the alkali metal compound is not particularly limited, but when the alkali metal compound is solid, a method of impregnating the supported ruthenium oxide after dissolving in water or an organic solvent is convenient.

  The catalyst to which the alkali metal compound has been added may be dried as necessary. The drying temperature is 20 to 150 ° C., preferably 40 to 100 ° C., and the drying time is 30 minutes to 24 hours.

  The catalyst thus obtained, in which an alkali metal compound and a ruthenium compound containing ruthenium oxide are supported on a carrier, can be used as a catalyst for catalytic oxidation reaction with hydrogen chloride oxygen.

  As the reaction method, a known reaction method as described in JP-A-2002-79093 is used.

When the reaction temperature is high, the equilibrium conversion rate of the reaction is lowered, so that it is desired to react at a low temperature, preferably 100 to 500 ° C, more preferably 200 to 450 ° C. The reaction pressure is usually about atmospheric pressure to 50 atmospheres. As the oxygen source, air may be used as it is, or oxygen-enriched air or pure oxygen may be used. The theoretical molar amount of oxygen with respect to hydrogen chloride is 1/4 mole, but it is usually supplied 0.1 to 10 times the theoretical amount. In addition, the amount of the catalyst used in the fixed bed gas-phase circulation method is appropriately set at about 10 to 20000 h ^{−1 in} terms of a ratio GHSV to the supply rate of the raw material hydrogen chloride under atmospheric pressure.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the present invention, the reaction rate (%) is defined as follows.
Hydrogen chloride conversion (%) = [chlorine production (mol / min) × 2 / hydrogen chloride supply (mol / min)] × 100

Example 1
A catalyst was prepared by an impregnation method similar to the method described in Example 24 of JP-A-10-194705. That is, 100.0 g of titanium oxide powder (Ishihara Sangyo Co., Ltd., PT-101) and 2.0 g of methylcellulose (Shin-Etsu Chemical Co., Ltd., Metrolose 65SH-4000) are mixed, and then 29.2 g of pure water, titanium oxide sol (Sakai Chemical Co., Ltd. CSB, TiO ₂ content 38 mass%) 13.2 g was added and kneaded. This mixture was extruded into a noodle shape having a diameter of 3.0 mmφ and a length of about 3 to 6 mm to obtain a molded body. The obtained molded body was heated in air from room temperature to 800 ° C. in 2.2 hours, and calcined at the same temperature for 3 hours to obtain a white extruded titanium oxide carrier.
In 90.0 g of the obtained titanium oxide support, 6.836 g of ruthenium chloride (manufactured by NE Chemcat Co., Ltd., RuCl ₃ · nH ₂ O, Ru content 40.0 mass%) was dissolved in 18.5 g of pure water. The prepared aqueous solution was impregnated and left at 25 ° C. for 18 hours. Next, 51.9 g of the obtained solid was heated from room temperature to 250 ° C. under air flow in 1.3 hours, calcined at the same temperature for 2 hours, and 46.8 g of a blue-gray extruded catalyst ( A) was obtained.

Next, 36.0 g of the catalyst (A) was filtered and washed with 3.6 kg of pure water, and then dried at 60 ° C. for 12 hours. 10.0 g of the obtained dried product was impregnated with an aqueous solution prepared by dissolving 9.6 mg of potassium chloride (Wako Pure Chemical Industries, Ltd.) in 2.1 g of pure water. Subsequently, it dried at 60 degreeC for 2 hours, and the potassium chloride containing catalyst was obtained (B). In addition, the calculated value of the potassium chloride content with respect to ruthenium oxide was KCl / RuO ₂ × 100 = 2.5 wt%.
The following short-term life test (1211 hours) was carried out in order to confirm the change in catalyst activity over time. That is, 1.5 g of the catalyst (B) prepared by the above-described method was packed in a nickel reaction tube (inner diameter: 14 mm). Hydrogen chloride 94 ml / min, oxygen 47 ml / min, nitrogen containing 5% by volume of carbon monoxide 3.76 ml / min and water 2.4 ml / min (both converted to standard conditions) are converted into hydrogen chloride in advance. Was adjusted to a gas composition of 50% or more, and then supplied to the packed bed, and the hot spot was set to 300 ° C. After 395 hours of operation at 300 ° C., the catalyst amount was reduced to 1.2 g and the hot spot was raised to 380 ° C. After operating at 380 ° C. for 816 hours, the catalyst was extracted from the reaction tube.
With respect to the catalyst (B), the activity of each of the catalyst not used in the reaction and the catalyst used in the short-term life test was evaluated as follows.
1.0 g of catalyst was diluted with 12 g of α-alumina spheres (Nikkato Co., Ltd., SSA995) having a diameter of 2 mm and filled into a nickel reaction tube (inner diameter 14 mm), and 12 g of α-alumina spheres were preheated on the upper part of the catalyst layer. Filled as a layer. Hydrogen chloride 80 ml / min and oxygen 40 ml / min (both 0 ° C. and 1 atm) were supplied under normal pressure, and the catalyst layer was heated to 281 to 282 ° C. At 1.5 hours after the start of the reaction, sampling was performed by circulating the gas at the outlet of the reaction tube through a 30% by mass aqueous potassium iodide solution. The amount of hydrogen chloride was measured. The conversion rate of hydrogen chloride is shown in Table 1.

Comparative Example 1
The reaction was conducted in the same manner as in Example 1 except that the catalyst (A) obtained before adding potassium chloride obtained in Example 1 was used. The conversion rate of hydrogen chloride is shown in Table 1.

Claims (1)

A method for producing a catalyst in which an alkali metal compound and a ruthenium compound containing ruthenium oxide are supported on a carrier, which is used in producing chlorine by oxidizing hydrogen chloride with oxygen, wherein the ruthenium compound containing ruthenium oxide in advance is used. A method for producing a catalyst for chlorine production, comprising adding an alkali metal compound after preparing a supported catalyst.