JP4438771B2 - Method for producing oxidation catalyst, method for producing chlorine, and method for oxidizing carbon monoxide and / or unsaturated hydrocarbon - Google Patents

Description

  The present invention relates to a method for producing an oxidation catalyst. The present invention also relates to a method for producing chlorine by oxidizing hydrogen chloride with oxygen using the catalyst produced by this method. Furthermore, the present invention also relates to a method for oxidizing carbon monoxide and / or unsaturated hydrocarbons with oxygen using the catalyst produced by the above method.

  As a catalyst for producing chlorine by oxidizing hydrogen chloride with oxygen, it is effective to use ruthenium from the viewpoint of activity. For example, JP-A-9-67103 (Patent Document 1) and JP-A-10-10 Japanese Laid-Open Patent Publication No. 194705 (Patent Document 2) discloses that a metal ruthenium or a ruthenium compound, a supported metal ruthenium or a supported ruthenium compound in which these are supported on a carrier are used for the catalyst. These ruthenium catalysts are also useful as catalysts for oxidizing carbon monoxide and unsaturated hydrocarbons with oxygen. For example, during the production of chlorine, the ruthenium catalysts are oxidized as impurities in the raw material hydrogen chloride-containing gas. When carbon or unsaturated hydrocarbon is contained, it can also function as a catalyst for oxidizing these impurities to carbon dioxide with oxygen to make them harmless.

  For example, Japanese Patent Laid-Open No. 2001-246231 (Patent Document 3) uses a catalyst containing metal ruthenium and / or a ruthenium compound to oxidize carbon monoxide in a hydrogen chloride-containing gas, It is disclosed to oxidize hydrogen chloride with oxygen. Japanese Patent Laid-Open No. 2002-226205 (Patent Document 4) discloses that a catalyst containing a ruthenium complex oxide is used to oxidize carbon monoxide in a hydrogen chloride-containing gas and hydrogen chloride in the gas. Is oxidized with oxygen.

JP-A-9-67103 JP-A-10-194705 JP 2001-246231 A JP 2002-226205 A

  The ruthenium catalysts disclosed in Patent Documents 1 to 4 have a problem that the oxidation activity tends to decrease. Therefore, as a result of earnest research to develop a ruthenium catalyst having excellent sustainability of oxidation activity, the present inventor has found that a catalyst suitable for the purpose can be produced by contact treatment of ruthenium oxide with a specific gas, The present invention has been completed.

  That is, the present invention provides a method for producing an oxidation catalyst by bringing ruthenium oxide into contact with a gas containing hydrogen chloride and / or chlorine and substantially no oxygen.

  The present invention also provides a method for producing chlorine by oxidizing hydrogen chloride with oxygen in the presence of the catalyst produced by the above method. Furthermore, the present invention also provides a method for oxidizing carbon monoxide and / or unsaturated hydrocarbons with oxygen in the presence of the catalyst produced by the above method.

  According to the present invention, it is possible to produce a catalyst having excellent oxidation activity sustainability, and by using the catalyst thus obtained, oxygen oxidation of hydrogen chloride, carbon monoxide, and unsaturated hydrocarbon can be stabilized over a long period of time. Can be done.

  In the method for producing an oxidation catalyst of the present invention, the ruthenium oxide used as a raw material may be substantially composed of only ruthenium oxide, or is supported ruthenium oxide in which ruthenium oxide is supported on a carrier. Alternatively, it may be a complex oxide or mixed oxide composed of ruthenium oxide and another oxide. Among these, supported ruthenium oxide is preferably used.

  When using the supported ruthenium oxide, examples of the carrier for supporting the ruthenium oxide include oxides such as alumina, silica, titanium oxide, zirconium oxide, niobium oxide, activated carbon, and the like. A composite oxide or mixed oxide composed of two or more, for example, two or more of the above oxides may be used. Among these, a carrier made of titanium oxide having a rutile crystal structure is preferably used.

  For example, as described in JP-A-2002-79093, the supported ruthenium oxide is supported on a carrier with a ruthenium compound such as ruthenium chloride, and then reduced with hydrazine if necessary, and then calcined in an atmosphere containing an oxygen-containing gas. By doing so, it can be suitably prepared. At that time, examples of the method of supporting the ruthenium compound on the carrier include a method of impregnating the carrier with the ruthenium compound solution, a method of immersing the carrier in the ruthenium compound solution, and adsorbing the ruthenium compound to the carrier. Is mentioned.

The loading of ruthenium oxide in the supported ruthenium oxide is expressed as a weight ratio of ruthenium oxide to the total weight of the carrier and ruthenium oxide, and is usually 0.1 to 20% by weight, preferably 0.5 to 15% by weight, more preferably 1 to 15% by weight. Normally, the ruthenium oxide in ruthenium oxide has an oxidation number of +4, and the ruthenium oxide is ruthenium dioxide (RuO ₂ ). However, ruthenium oxide having other oxidation numbers or other forms of ruthenium oxide may be included. .

  In the present invention, an oxidation catalyst is produced by contact-treating ruthenium oxide as described above with a predetermined gas, that is, a gas containing hydrogen chloride and / or chlorine and substantially not containing oxygen. By such a method, it is possible to produce an oxidation catalyst in which the oxidation activity is difficult to decrease, that is, the oxidation activity has excellent durability.

  When the said gas contains hydrogen chloride, the density | concentration is 1-100 volume% normally, Preferably it is 50-100 volume%. Moreover, when the said gas contains chlorine, the density | concentration is 0.01-100 volume% normally, Preferably it is 0.02-5 volume%. As the gas, a gas containing hydrogen chloride is particularly preferably used. In addition, the gas is a gas that does not substantially contain oxygen. For example, the gas does not contain oxygen at all, or even if oxygen is contained, the content is 1% by volume or less of the total amount of hydrogen chloride and chlorine. Gas. Examples of components other than hydrogen chloride and chlorine that can be included in the gas include inert gases such as nitrogen and helium.

  The higher the temperature of the contact treatment is, the more effective it is. If it is too low, it takes a long time. Therefore, it is usually 200 ° C. or higher, preferably 400 ° C. or higher, more preferably 500 ° C. or higher. Is usually 1000 ° C. or less, preferably 700 ° C. or less, and more preferably 650 ° C. or less. The contact treatment time should be shorter at high temperatures and longer at low temperatures, usually 1 minute to 100 hours, preferably 5 minutes to 24 hours, more preferably 15 minutes to 4 hours. is there.

The contact treatment may be performed, for example, by a stationary batch method, a fixed bed vapor phase circulation method, or a fluidized bed vapor phase circulation method. In the case of the fixed bed gas phase circulation method, the gas supply rate is usually 0.01 to 50000 h, expressed in terms of the volume supply rate of the ruthenium oxide packed bed (0 ° C., 1 atm), that is, GHSV. ⁻¹ , preferably ¹ to 10000 h ⁻¹ , more preferably 10 to 1000 h ⁻¹ .

  Examples of the shape of the oxidation catalyst include a spherical shape, a cylindrical shape, a ring shape, and an amorphous particle shape. Moreover, as the molding method, for example, extrusion molding, tableting molding, spray molding and the like can be mentioned, and after molding, pulverization and classification to an appropriate size may be performed. At that time, the catalyst diameter should be 10 mm or less, where the catalyst diameter is the diameter of a sphere in the case of a sphere, the diameter of a circle of a cross section in the case of a cylinder, and any cross section in the case of other shapes. Means the longest diameter. Note that the molding may be performed after the above contact treatment or may be performed before the contact treatment. When using supported ruthenium oxide as ruthenium oxide, it is possible to adopt a form in which a carrier is molded and a ruthenium compound is supported thereon. Further, the oxidation catalyst may be diluted with an inert substance as necessary.

  The oxidation catalyst thus obtained is usually characterized by a high temperature at the end of weight loss in hydrogen thermogravimetry. That is, as shown in the examples to be described later, when the temperature of this oxidation catalyst is gradually raised in a hydrogen gas stream, the temperature at the time when the weight loss ends, that is, at the time when the reduction by hydrogen ends. Specifically, the temperature is as high as 180 ° C. or higher. And it exists in the tendency for the sustainability of oxidation activity to become high, so that this temperature is high.

  The oxidation catalyst according to the present invention described above is useful as a catalyst for oxidizing various substrates with oxygen. Among them, the oxidation catalyst according to the present invention can be suitably used as a catalyst for oxidizing hydrogen chloride as a substrate and oxidizing it with oxygen, whereby chlorine can be produced stably over a long period of time.

  Further, the oxidation catalyst according to the present invention is effective as a catalyst for oxidizing carbon monoxide or unsaturated hydrocarbon as a substrate and oxidizing it with oxygen. Here, as examples of unsaturated hydrocarbons, Mention may be made of aliphatic hydrocarbons such as ethylene, acetylene, propylene, butene and butadiene, alicyclic hydrocarbons such as cyclopentene, cyclopentadiene, cyclohexene and cyclohexadiene, and aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene. it can.

  In addition, when chlorine is produced by oxidizing hydrogen chloride with oxygen, carbon monoxide and unsaturated hydrocarbons are contained as impurities in the raw material hydrogen chloride-containing gas due to its preparation method and source. These impurities can poison the catalyst and reduce its hydrogen chloride oxidation activity. Therefore, in the prior art, such impurities are removed and then subjected to an oxidation reaction of hydrogen chloride, or hydrogen chloride is oxidized to chlorine while oxidizing these impurities to carbon dioxide to make them harmless. However, even in the latter case, the sustainability of the catalyst activity was not sufficient. As described above, the oxidation catalyst according to the present invention uses carbon monoxide and / or a gas containing unsaturated hydrocarbon and hydrogen chloride as a raw material gas, and converts carbon monoxide and / or unsaturated hydrocarbon with oxygen. In addition to oxidation, it can also be suitably used as a catalyst for oxidizing hydrogen chloride with oxygen, whereby it can stably oxidize carbon monoxide and / or unsaturated hydrocarbons over a long period of time while oxidizing chlorine. Can be manufactured.

  Therefore, when producing chlorine by oxidizing hydrogen chloride with oxygen using the oxidation catalyst according to the present invention, the raw material hydrogen chloride-containing gas includes, for example, a gas produced by the reaction of hydrogen and chlorine, or heating of hydrochloric acid. In addition to gas generated by chlorination, dehydrochlorination reaction, pyrolysis reaction or combustion reaction of chlorine compounds, carbonylation reaction of organic compounds with phosgene, various by-product gases generated by chlorination reaction of organic compounds with chlorine, and incineration Gases that can contain carbon monoxide or unsaturated hydrocarbons as impurities, such as combustion exhaust gas generated from a furnace, can also be used. The content ratio of carbon monoxide and / or unsaturated hydrocarbon to hydrogen chloride is preferably about 5 mol% or less.

  Usually, air or pure oxygen is used as the oxygen source. Pure oxygen can be prepared by an air pressure swing method, a cryogenic separation method, or the like. The amount of oxygen used is usually 0.1 mol times or more, preferably 0.2 mol times or more, relative to the substrate.

  The reaction temperature is usually 100 to 500 ° C, preferably 200 to 500 ° C, more preferably 250 to 400 ° C. If the reaction temperature is too low, it is difficult to maintain the stable activity of the catalyst. On the other hand, if the reaction temperature is too high, the catalyst component tends to volatilize. The reaction pressure is usually about 0.1 to 5 MPa.

  The reaction method may be a fixed bed method or a fluidized bed method, and usually a gas phase reaction such as a fixed bed gas phase circulation method or a fluid bed gas phase circulation method is preferably employed. The fixed bed gas phase circulation method has an advantage that it is easy to achieve a high conversion rate because the reaction product gas and the catalyst can be easily separated and the raw material gas and the catalyst can be sufficiently brought into contact with each other. On the other hand, the fluidized bed gas phase circulation method has an advantage that the temperature distribution width in the reactor can be reduced because heat removal in the reactor is easy to be performed.

When the reaction is carried out in a fixed bed gas-phase flow system, the supply rate of the gas containing the substrate and oxygen supplied to the reactor is the volume supply rate of the gas relative to the volume of the catalyst packed bed (0 ° C., converted to 1 atm) That is, it is usually 10 to 50000 h ⁻¹ in terms of GHSV, and the gas volume supply rate (0 ° C., 1 atm conversion) with respect to the cross-sectional area of the catalyst packed bed (cross-sectional area perpendicular to the gas supply direction), that is, It is usually 0.1 to 20 m / s in terms of the so-called superficial gas linear velocity.

  Examples of the present invention will be shown below, but the present invention is not limited thereto. In the examples, the gas supply rate (ml / min) is a converted value of 0 ° C. and 1 atm unless otherwise specified.

Reference Example 1 (Preparation of supported ruthenium oxide)
50 parts by weight of titanium oxide (STR-60R, 100% rutile type manufactured by Sakai Chemical Co., Ltd.), 100 parts by weight of α-alumina (AES-12, manufactured by Sumitomo Chemical Co., Ltd.), and 19.2 parts by weight of titania sol [堺CSB manufactured by Kagaku Co., Ltd., titania content 38% by weight] and 3 parts by weight of methylcellulose [Metroze 65SH-4000 manufactured by Shin-Etsu Chemical Co., Ltd.] were mixed, and then pure water was added and kneaded. This mixture was extruded into a cylindrical shape having a diameter of 3.0 mmφ, dried, and then crushed to a length of about 4 to 6 mm. The obtained molded body was fired in air at 800 ° C. for 3 hours to obtain a carrier made of a mixture of titanium oxide and α-alumina. This support is impregnated with an aqueous solution of ruthenium chloride, dried, and then calcined in air at 250 ° C. for 2 hours, whereby ruthenium oxide is supported on the support at a loading ratio of 2% by weight. Ruthenium oxide was obtained.

Example 1
60.0 g of the supported ruthenium oxide obtained in Reference Example 1 was filled in a quartz reaction tube having an inner diameter of 21 mm, and nitrogen gas was supplied at a rate of 300 ml / min to 0.5 to 605 ° C. from room temperature. After raising the temperature over time, the mixture was treated at 605 ° C. for 0.5 hour while supplying hydrogen chloride gas at a rate of 300 ml / min to obtain 59.6 g of a catalyst.

  The obtained catalyst was subjected to hydrogen thermogravimetry. That is, by charging 0.02025 g of catalyst in a platinum dish and supplying hydrogen gas at a rate of 200 ml / min under normal pressure, the temperature is increased from room temperature to 300 ° C. at a rate of 5.0 ° C./min. Weighing was performed. Table 1 shows the temperature (reduction end temperature) at the end of weight reduction of the catalyst. In addition, the weight of the catalyst after hydrogen thermogravimetry was 0.02002 g.

  Next, an oxidation reaction (accelerated life test under high SV conditions) was performed using the obtained catalyst. That is, 0.5 g of catalyst is packed in a quartz reaction tube having an inner diameter of 13 mm, and carbon monoxide gas is 4.5 ml / min, hydrogen chloride gas is 150 ml / min (0.40 mol / h), oxygen gas Was supplied at a rate of 75 ml / min and nitrogen gas at a rate of 40.5 ml / min under normal pressure, and the reaction tube was heated to 290 ° C. to carry out an oxidation reaction for 50 hours. When 1.5 hours passed from the start of the reaction and 44 hours passed, the conversion rate of hydrogen chloride and the conversion rate of carbon monoxide were determined by the following method and are shown in Table 1 together with the catalyst layer temperature.

[Conversion rate of hydrogen chloride]
Sampling was performed for 20 minutes by circulating the gas at the outlet of the reaction tube through a 30 wt% potassium iodide aqueous solution, and the amount of chlorine produced was measured by the iodometric titration method to determine the chlorine production rate (mol / h). From this chlorine production rate and the above-mentioned hydrogen chloride supply rate, the conversion rate of hydrogen chloride was calculated by the following equation.

  Hydrogen chloride conversion (%) = [chlorine production rate (mol / h) × 2 ÷ hydrogen chloride feed rate (mol / h)] × 100.

[Conversion rate of carbon monoxide]
Residual gas that was not absorbed in the potassium iodide aqueous solution for 12 to 19 minutes from the start of the sampling was collected in a gas bag, analyzed by gas chromatography, and the residual amount (mol) of carbon monoxide and carbon dioxide were analyzed. The amount of carbon produced (mol) was determined, and the conversion rate of carbon monoxide was calculated by the following equation.

  Carbon monoxide conversion (%) = [carbon dioxide production amount (mol) / {carbon monoxide remaining amount (mol) + carbon dioxide production amount (mol)}] × 100

Comparative Example 1
About 0.02062 g of the supported ruthenium oxide obtained in Reference Example 1, hydrogen thermogravimetry was performed in the same manner as in Example 1. Table 1 shows the temperature (reduction end temperature) at the end of weight reduction of the catalyst. The weight of the catalyst after the thermogravimetric measurement was 0.02044 g.

  Next, using the supported ruthenium oxide obtained in Reference Example 1 as a catalyst, an oxidation reaction was carried out in the same manner as in Example 1. When 1.5 hours passed and 44 hours passed after the start of the reaction, the conversion rate of hydrogen chloride and the conversion rate of carbon monoxide were determined in the same manner as in Example 1, and the results are shown in Table 1 together with the catalyst layer temperature.

In Comparative Example 1, the conversion rate of carbon monoxide decreased by 11.8 points as a difference and decreased by 54% as a ratio from the time when 1.5 hours passed from the start of the reaction to the time when 44 hours passed. The conversion rate of hydrogen chloride decreased by 1.1 points as a difference and decreased by 37% as a ratio. On the other hand, in Example 1, although the initial activity was slightly low, the conversion rate of carbon monoxide was suppressed to 8.1 points as a difference, and the decrease as a ratio was suppressed to 40%. As for the conversion rate of hydrogen chloride, the decrease as a difference is suppressed to 0.4 points, and the decrease as a ratio is suppressed to 18%. Further, in Example 1, a catalyst excellent in sustainability of oxidation activity can be produced even when the supported ruthenium oxide is contact-treated with chlorine gas instead of hydrogen chloride gas in the production of the catalyst. Reduction is suppressed.

Claims (7)

Hydrogen chloride and carbon monoxide, characterized by contacting ruthenium oxide with a gas containing hydrogen chloride and / or chlorine and having an oxygen content of 1% by volume or less based on the total amount of hydrogen chloride and chlorine And a method for producing an oxidation catalyst for oxidizing at least one selected from the group consisting of unsaturated hydrocarbons .   The method according to claim 1, wherein the gas is a gas containing hydrogen chloride.   The method according to claim 1 or 2, wherein the contact between ruthenium oxide and the gas is performed at 500 ° C or higher.   The method according to any one of claims 1 to 3, wherein a supported ruthenium oxide in which ruthenium oxide is supported on a carrier is used as the ruthenium oxide.   A method for producing chlorine, comprising oxidizing hydrogen chloride with oxygen in the presence of the catalyst produced by the method according to any one of claims 1 to 4.   Carbon monoxide and / or unsaturated, characterized by oxidizing carbon monoxide and / or unsaturated hydrocarbons with oxygen in the presence of the catalyst produced by the process according to any one of claims 1 to 4. Hydrocarbon oxidation method.   In the presence of the catalyst produced by the method according to any one of claims 1 to 4, carbon monoxide and / or unsaturated hydrocarbons are oxidized with oxygen, and hydrogen chloride is oxidized with oxygen. To produce chlorine.