JP2007007521A - Method for activating chlorine production catalyst and method for producing chlorine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for activating a chlorine production catalyst to be used in such a reaction that hydrogen chloride is oxidized by oxygen, by which the activity of the activity-deteriorated chlorine production catalyst can be recovered effectively. <P>SOLUTION: The activity-deteriorated chlorine production catalyst is brought into contact with a gas consisting substantially of only oxygen and/or an inert component. The inert component can be selected from steam, nitrogen, argon and helium. A ruthenium catalyst, particularly, a ruthenium oxide-containing catalyst is preferably used as the chlorine production catalyst. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for activating a catalyst for producing chlorine used in a reaction for oxidizing hydrogen chloride with oxygen. The present invention also relates to a method for producing chlorine by oxidizing hydrogen chloride with oxygen using a catalyst activated by this method.

  As a method for producing chlorine by oxidizing hydrogen chloride with oxygen, a method using a copper catalyst called a Deacon catalyst has been known for a long time. In addition, a method using a chromium catalyst (for example, see Patent Documents 1 to 4), a method using a ruthenium catalyst (for example, see Patent Documents 5 to 10), and the like have been proposed. This oxidation reaction is usually performed at a reaction temperature of about 100 to 500 ° C. while supplying hydrogen chloride and oxygen into a reactor in which a catalyst is present.

JP-A-61-136902 JP 61-275104 A JP 62-113701 A JP-A-62-270405 JP-A-9-67103 JP 10-338502 A JP 2000-229239 A JP 2000-281314 A JP 2002-79093 A JP 2002-292279 A

  In the oxidation reaction, usually, the activity of the catalyst gradually decreases as the operation time elapses, that is, as the catalyst usage time elapses. In addition, an unscheduled decrease in catalyst activity may occur due to operational mistakes during operation or equipment malfunctions. If the catalyst whose activity has been reduced in this way can be activated and reused, the useful life of the catalyst is extended, which is advantageous in terms of cost. Accordingly, an object of the present invention is to provide a method capable of effectively recovering the activity of a catalyst for producing chlorine whose activity has been lowered.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by treating a catalyst for chlorine production with reduced activity with a predetermined gas, and have completed the present invention. That is, the present invention relates to a method for activating a catalyst for producing chlorine used in a reaction in which hydrogen chloride is oxidized with oxygen, wherein the catalyst with reduced activity is converted to a gas consisting essentially of oxygen and / or an inert component. It is intended to provide a method for activating a catalyst for producing chlorine, characterized in that it is brought into contact with the catalyst.

  Moreover, according to this invention, the method of manufacturing chlorine by oxidizing hydrogen chloride with oxygen in presence of the catalyst activated by the said method is also provided.

  According to the activation method of the present invention, it is possible to effectively recover the activity of a catalyst for chlorine production whose activity has decreased. By activating and reusing the catalyst by this method, chlorine can be advantageously produced in terms of cost. Can be manufactured.

  The catalyst to be activated by the present invention is a catalyst for producing chlorine that is used when producing chlorine by oxidizing hydrogen chloride with oxygen. Examples of the chlorine production catalyst include a copper catalyst, a chromium catalyst, and a ruthenium catalyst.

  Preferable examples of the copper catalyst include a catalyst obtained by adding various compounds as a third component to copper chloride and potassium chloride, generally called Deacon catalyst. Preferable examples of the chromium catalyst include catalysts containing chromium oxide as disclosed in Patent Documents 1 to 4. Moreover, as a suitable example of a ruthenium catalyst, the catalyst containing ruthenium oxide as shown in patent documents 5-10 can be mentioned.

  Especially, the method of this invention is used suitably with respect to the catalyst containing a ruthenium catalyst, especially a ruthenium oxide. The catalyst containing ruthenium oxide, for example, may be substantially composed of only ruthenium oxide, or ruthenium oxide is supported on a support such as alumina, titania, silica, zirconia, niobium oxide, activated carbon or the like. It may be a supported ruthenium oxide or a complex oxide composed of ruthenium oxide and other oxides such as alumina, titania, silica, zirconia, niobium oxide and the like.

  The production of chlorine using the catalyst as described above is usually carried out continuously under gas phase conditions while supplying hydrogen chloride and oxygen into a fixed bed reactor packed with the catalyst or a fluidized bed reactor in which the catalyst is fluidized. Done in the formula. In this case, for example, as disclosed in JP-A-2001-19405, it is advantageous to supply water vapor in addition to hydrogen chloride and oxygen because the temperature distribution of the catalyst layer can be smoothed.

The reaction temperature is usually 100 to 500 ° C., preferably 200 to 400 ° C., and the reaction pressure is usually about 0.1 to 5 MPa. Air may be used as the oxygen source. Pure oxygen may be used. In order to completely oxidize hydrogen chloride to chlorine, theoretically, 1/4 mole of oxygen is required for 1 mole of hydrogen chloride, but usually 0.1 to 10 times the theoretical amount of oxygen is used. The The supply rate of hydrogen chloride is usually about 10 to 20000 h ^{−1 in} terms of the volume supply rate of gas per volume of the catalyst layer (converted to 0 ° C. and 1 atm), that is, GHSV.

  Examples of the hydrogen chloride-containing gas that can be used as a hydrogen chloride source include a gas generated by the reaction of hydrogen and chlorine, a gas generated by heating hydrochloric acid, a pyrolysis reaction or combustion reaction of a chlorine compound, and an organic compound by phosgene. Carbonylation reaction of organic compounds, chlorination reaction of organic compounds with chlorine, various by-product gases generated by the production of chlorofluoroalkane, and combustion exhaust gas generated from an incinerator.

  Here, examples of the pyrolysis reaction of a chlorine compound include a reaction in which vinyl chloride is produced from 1,2-dichloroethane, a reaction in which tetrafluoroethylene is produced from chlorodifluoromethane, and the carbonylation of an organic compound with phosgene. Examples of the reaction include a reaction in which an isocyanate is generated from an amine, a reaction in which a carbonate ester is generated from a hydroxy compound, and the chlorination reaction of an organic compound with chlorine includes, for example, a reaction in which allyl chloride is generated from propylene, Examples include a reaction in which ethyl chloride is produced from ethane, a reaction in which chlorobenzene is produced from benzene, and the like. Examples of the production of chlorofluoroalkane include dichlorodifluoromethane and trichloromonofluoromethane by the reaction of carbon tetrachloride and hydrogen fluoride, and dichlorodifluoromethane and trichloromonofluoro by the reaction of methane, chlorine and hydrogen fluoride. Examples include methane production.

  In the oxidation reaction, usually, the activity of the catalyst gradually decreases as the operation time elapses, that is, as the catalyst usage time elapses. In addition, an unscheduled decrease in catalyst activity may occur due to operational mistakes during operation or equipment malfunctions. For example, if the reaction temperature becomes difficult to control and the catalyst is exposed to high temperature for a long time, or the supply of oxygen is stopped and the catalyst is in contact with hydrogen chloride for a long time in the absence of oxygen, Activity may decrease. Furthermore, even if the catalyst is in contact with hydrogen chloride for a long time in the absence of oxygen because the start of oxygen supply is delayed during start-up, or when the reaction is temporarily stopped, the supply stop of hydrogen chloride is delayed. Activity may be reduced. Therefore, in the present invention, the activation treatment is performed by bringing the catalyst into contact with a gas consisting essentially of oxygen and / or an inert component in order to recover the activity of the catalyst whose activity has been reduced in this way.

  The gas may consist essentially of oxygen, may consist essentially of inert components, or may consist essentially of oxygen and inert components. May be. Moreover, you may perform activation process in multiple steps, using multiple types of these gas. When a gas containing oxygen is used, pure oxygen or air can be used as the oxygen source, and the oxygen concentration in the gas is usually 5% by volume or more. Further, the inert component is a neutral component that does not substantially oxidize or reduce the catalyst, and does not substantially exhibit acidity or basicity. For example, water vapor, nitrogen, argon, helium These may be mentioned, and two or more of them may be mixed and used as necessary.

The temperature at the time of activation treatment, that is, when the catalyst having decreased activity is brought into contact with the gas is usually 0 to 400 ° C, preferably 200 to 400 ° C. If this temperature is too low, it takes a long time for the activation treatment, and if this temperature is too high, the catalyst component tends to volatilize. Moreover, the pressure at the time of an activation process is 0.1-3 Mpa normally, Preferably it is 0.1-1 Mpa. Similarly to the oxidation reaction, the activation treatment may be performed in a fixed bed format or a fluidized bed format. The gas supply rate is usually about ¹ to 100000 h ^{−1 in} terms of the volume supply rate of gas per volume of the catalyst layer (0 ° C., converted to 1 atm), that is, GHSV. Moreover, the time of an activation process is about 1 to 24 hours normally.

  The catalyst thus activated can be reused in the oxidation reaction. By activating and reusing the catalyst in this way, the catalyst cost can be reduced and chlorine can be produced advantageously in terms of cost. be able to.

  When the oxidation reaction is performed in a fixed bed format, the oxidation reaction is performed while supplying a raw material gas consisting of hydrogen chloride and oxygen into a reactor packed with the catalyst, and the catalyst activity is such that it is difficult to continue the operation. Is reduced, the supply gas is switched from the source gas to the activation treatment gas and the activation treatment is performed for a predetermined time, the supply gas is then switched from the activation treatment gas to the source gas, and the oxidation reaction is performed again. A prescription of repeating these activation treatments and oxidation reactions as necessary is advantageously employed. Further, when the oxidation reaction is performed in a fluidized bed format, as in the case of the fixed bed format, in addition to a prescription in which an oxidation reaction and an activation treatment are alternately performed by switching a gas to be supplied, while performing an oxidation reaction, a reactor Part of the catalyst is continuously or intermittently extracted from the catalyst, activated in another container, and then returned to the reactor, that is, the catalyst is circulated between the reactor and the container for activation treatment. Is advantageously employed.

  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
(A) Preparation of catalyst 50 parts by weight of titanium oxide [STR-60R manufactured by Sakai Chemical Co., Ltd., 100% rutile type], 100 parts by weight of α-alumina [AES-12 manufactured by Sumitomo Chemical Co., Ltd.], titania sol 13 2 parts by weight (CSB manufactured by Sakai Chemical Co., Ltd., titania content 38% by weight) and 2 parts by weight of methylcellulose [Metroze 65SH-4000 manufactured by Shin-Etsu Chemical Co., Ltd.] were mixed, and then pure water was added. 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.

(B) Evaluation of new catalyst 1 g of an unused new catalyst obtained in (a) above was filled in a nickel reaction tube having an inner diameter of 13 mm, and α-alumina spheres were used as a preheating layer on the gas inlet side of the catalyst layer. 12 g of SSA995 manufactured by Nikkato Co., Ltd. was charged. In this, while supplying nitrogen gas at a rate of 80 ml / min, the reaction tube was immersed in a salt bath using molten salt [potassium nitrate / sodium nitrite = 1/1 (weight ratio)] as a heat medium, and the catalyst layer Was raised to 281-282 ° C. Next, the supply of nitrogen gas is stopped, and the catalyst layer temperature is supplied by supplying hydrogen chloride gas at a rate of 80 ml / min (0.35 mol / h) and oxygen gas at a rate of 40 ml / min (0.20 mol / h). The oxidation reaction was performed at 282 to 283 ° C. At 1.5 hours from the start of the reaction, sampling was performed for 20 minutes by circulating the gas at the outlet of the reaction tube through a 30 wt% aqueous potassium iodide solution, and the amount of chlorine produced was measured by the iodometric titration method. The rate (mol / h) was determined. The conversion rate of hydrogen chloride was calculated from the chlorine production rate and the above-mentioned hydrogen chloride supply rate by the following formula, and is shown in Table 1.

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

Reference example 2
(A) Acquisition of deteriorated catalyst 1 g of an unused new catalyst obtained in Reference Example 1 (a) is filled in a nickel reaction tube having an inner diameter of 13 mm, and α-alumina is used as a preheating layer on the gas inlet side of the catalyst layer. A sphere [SSA995 manufactured by Nikkato Co., Ltd.] 12 g was filled. In this, while supplying nitrogen gas at a rate of 80 ml / min, the reaction tube was immersed in a salt bath using molten salt [potassium nitrate / sodium nitrite = 1/1 (weight ratio)] as a heat medium, and the catalyst layer Was raised to 253 to 254 ° C., and the reaction tube inlet was raised to a gauge pressure of 0.5 MPa. Next, the supply of nitrogen gas was stopped, and the catalyst layer temperature was maintained at 253 to 254 ° C. for 5 hours while supplying hydrogen chloride gas at a rate of 80 ml / min.

(B) Evaluation of deteriorated catalyst Subsequent to the above (b), the temperature of the catalyst layer was raised to 281 to 282 ° C. and the reaction tube inlet was returned to normal pressure, and then hydrogen chloride gas was fed at a rate of 80 ml / min. While being supplied, oxygen gas was supplied at a rate of 40 ml / min to carry out an oxidation reaction at a catalyst layer temperature of 281 to 282 ° C. At 1.5 hours from the start of the reaction, sampling was performed to determine the chlorine production rate in the same manner as in Reference Example 1 (b), and the conversion rate of hydrogen chloride was calculated. The results are shown in Table 1.

Example 1
(A) Activation process of deteriorated catalyst Following the above Reference Example 2 (b), the supply of hydrogen chloride gas was stopped, and oxygen gas was supplied at a rate of 40 ml / min. Held for hours.

(B) Evaluation of activated catalyst Subsequent to (a) above, the oxygen gas was supplied at a rate of 40 ml / min and hydrogen chloride gas was supplied at a rate of 80 ml / min, whereby the catalyst layer temperature was 282 to 283 ° C. The oxidation reaction was carried out. At 1.5 hours from the start of the reaction, sampling was performed to determine the chlorine production rate in the same manner as in Reference Example 1 (b), and the conversion rate of hydrogen chloride was calculated. The results are shown in Table 1.

Reference example 3
(A) Acquisition of deteriorated catalyst 5 g of an unused new catalyst obtained in Reference Example 1 (a) was filled in a nickel reaction tube having an inner diameter of 13 mm, and α-alumina was used as a preheating layer on the gas inlet side of the catalyst layer. A sphere [SSA995 manufactured by Nikkato Co., Ltd.] 12 g was filled. While supplying a mixed gas of nitrogen and water vapor [nitrogen / water vapor = 8/1 (volume ratio)] at a rate of 18 ml / min, molten salt [potassium nitrate / sodium nitrite = 1/1 (weight ratio) ] Was immersed in a salt bath using a heat medium, the temperature of the catalyst layer was raised to 253 to 254 ° C., and the pressure at the inlet of the reaction tube was increased to 0.5 MPa. Next, in addition to the above mixed gas of nitrogen and water vapor, hydrogen chloride gas was supplied at a rate of 80 ml / min, and the catalyst layer temperature was maintained at 253 to 254 ° C. for 5 hours.

  In order to take out the catalyst thus deteriorated from the reaction tube, the supply of the hydrogen chloride gas and the mixed gas of nitrogen and water vapor was stopped, and while the nitrogen gas was supplied at 80 ml / min, the reaction tube inlet was returned to normal pressure, The reaction tube was taken out from the salt bath, and the temperature of the catalyst layer was cooled to room temperature. Next, the deteriorated catalyst was extracted from the reaction tube and stored in air at room temperature for 28 days.

  The above-described operation for extracting or storing the deteriorated catalyst has an atmosphere gas condition that satisfies the provisions of the present invention. Therefore, as shown in Table 1 later, the deterioration catalyst obtained in Reference Example 3 is used. The activity (conversion rate of hydrogen chloride) is higher than the activity of the deteriorated catalyst obtained in Reference Example 2 above, but here, as one operation for obtaining the deteriorated catalyst, Reference Example 3 Described in.

(B) Evaluation of deteriorated catalyst 1 g of the deteriorated catalyst obtained in (a) above was filled in a nickel reaction tube having an inner diameter of 13 mm, and α-alumina sphere [Nikato Co., Ltd. SSA995] 12 g. In this, while supplying nitrogen gas at a rate of 80 ml / min, the reaction tube was immersed in a salt bath using molten salt [potassium nitrate / sodium nitrite = 1/1 (weight ratio)] as a heat medium, The temperature of the layer was raised to 281-282 ° C. Next, the supply of nitrogen gas is stopped, and the catalyst layer temperature is supplied by supplying hydrogen chloride gas at a rate of 80 ml / min (0.35 mol / h) and oxygen gas at a rate of 40 ml / min (0.20 mol / h). The oxidation reaction was performed at 281-282 ° C. At 1.5 hours from the start of the reaction, sampling was performed to determine the chlorine production rate in the same manner as in Reference Example 1 (b), and the conversion rate of hydrogen chloride was calculated. The results are shown in Table 1.

Example 2
(A) Activation treatment of deteriorated catalyst Subsequent to Reference Example 3 (b) above, the supply of hydrogen chloride gas and oxygen gas is stopped, and the nitrogen gas is supplied at a rate of 80 ml / min, while the catalyst layer temperature is 281 to 282 ° C. Held for 1 hour.

(B) Evaluation of activated catalyst Subsequent to the above (a), the supply of nitrogen gas is stopped, hydrogen chloride gas is supplied at a rate of 80 ml / min, and oxygen gas is supplied at a rate of 40 ml / min. The oxidation reaction was performed at 283 ° C. At 1.5 hours from the start of the reaction, sampling was performed to determine the chlorine production rate in the same manner as in Reference Example 1 (b), and the conversion rate of hydrogen chloride was calculated. The results are shown in Table 1.

Claims (7)

  A method for activating a catalyst for producing chlorine used in a reaction in which hydrogen chloride is oxidized with oxygen, wherein the catalyst with reduced activity is brought into contact with a gas consisting essentially of oxygen and / or an inert component. A method for activating a catalyst for chlorine production.   The method of claim 1, wherein the gas consists essentially of oxygen.   The method of claim 1, wherein the gas consists essentially of an inert component.   The method of claim 1 wherein the gas consists essentially of oxygen and inert components.   The method according to claim 1, 3 or 4, wherein the inert component is selected from water vapor, nitrogen, argon and helium.   The method according to claim 1, wherein the catalyst is a catalyst containing ruthenium oxide. A method for producing chlorine, comprising activating a catalyst by the method according to claim 1 and oxidizing hydrogen chloride with oxygen in the presence of the activating catalyst.