JP2010274216A - Method of activating catalyst for producing chlorine, and method of producing chlorine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of activating a catalyst for producing chlorine, capable of effectively activating a catalyst for producing chlorine having deteriorated activity to suitably recover its catalytic activity. <P>SOLUTION: The method of activating a catalyst for producing chlorine, namely a method of activating a catalyst for producing chlorine to be used in a reaction wherein hydrogen chloride is oxidized with oxygen, is characterized by bringing the catalyst for producing chlorine having deteriorated activity to contact with an acidic liquid. The pH of the acidic liquid preferably is not higher than 5. The acidic liquid preferably is an aqueous solution of an inorganic acid dissolved therein. The catalyst for producing chlorine preferably includes ruthenium oxide. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for activating a catalyst for chlorine production with reduced activity, and a method for producing chlorine using a catalyst for chlorine production activated by this method.

Chlorine is useful as a raw material for vinyl chloride, phosgene and the like, and has been conventionally produced by a reaction in which hydrogen chloride is oxidized with oxygen in the presence of a catalyst for producing chlorine. However, the catalyst for chlorine production used in the reaction described above may have a reduced catalytic activity when subjected to a heat load, for example, under steady or unsteady conditions.
Therefore, as a method for activating a chlorine production catalyst (hereinafter also referred to as “deteriorated catalyst”) having a reduced activity, a method in which the deteriorated catalyst is brought into contact with a gas consisting essentially of oxygen and / or an inert gas ( Patent Document 1) and a method (Patent Document 2) in which a deteriorated catalyst is contacted with a reducing gas containing carbon monoxide and / or hydrogen have been proposed.

JP 2007-7521 A JP 2009-22917 A

  However, the catalyst for chlorine production activated by the above-described conventional activation method sometimes fails to obtain sufficiently satisfactory catalytic activity.

  Then, the subject of this invention is activating the catalyst for chlorine production in which activity fell, and the activation method of the catalyst for chlorine production which can recover | recover the catalyst activity favorably, and the catalyst activated by this method It is in providing the manufacturing method of the used chlorine.

  The present inventors have intensively studied to solve the above-mentioned problems. As a result, it has been found that the catalyst activity can be effectively recovered by a simple method in which the catalyst having decreased activity is brought into contact with the acidic liquid, and the present invention has been completed.

That is, the present invention has the following configuration.
(1) A method for activating a catalyst for producing chlorine used in a reaction for oxidizing hydrogen chloride with oxygen, comprising contacting a catalyst for producing chlorine with reduced activity in contact with an acidic liquid. Activation method.
(2) The method for activating a catalyst for producing chlorine according to (1), wherein the acidic solution has a pH of 5 or less.
(3) The method for activating a catalyst for producing chlorine according to (1) or (2), wherein the acidic liquid is an aqueous solution in which an inorganic acid is dissolved.
(4) The method for activating a catalyst for chlorine production according to any one of (1) to (3), wherein the catalyst for chlorine production is a catalyst containing ruthenium oxide.
(5) A method for producing chlorine in which hydrogen chloride is oxidized with oxygen in the presence of a catalyst, and the catalyst activated by the activation method according to any one of (1) to (4) is used as the catalyst. A method for producing chlorine characterized by the following.

  ADVANTAGE OF THE INVENTION According to this invention, the catalyst for chlorine manufacture in which activity fell can be activated effectively, and the catalyst activity can be recovered | restored favorably. This makes it possible to activate the chlorine production catalyst with reduced activity and reuse it in the reaction of oxidizing hydrogen chloride with oxygen, and advantageously produce chlorine in that the catalyst cost can be reduced. The effect is also obtained.

  In the method for activating a catalyst for producing chlorine according to the present invention, the catalyst to be activated is used for producing chlorine by a reaction in which hydrogen chloride is oxidized with oxygen (hereinafter also referred to simply as “oxidation reaction”). The catalyst is not particularly limited, and examples thereof include a copper catalyst, a chromium catalyst, and a ruthenium catalyst. Specifically, preferred examples of the copper catalyst include a catalyst obtained by adding various compounds as a third component to copper chloride and potassium chloride, generally referred to as a Deacon catalyst. The chromium catalyst contains chromium oxide as disclosed in JP-A-61-136902, JP-A-61-275104, JP-A-62-1113701, and JP-A-62-270405. A catalyst is preferred. Examples of the ruthenium catalyst include oxidation as disclosed in JP-A-9-67103, JP-A-10-338502, JP-A-2000-281314, JP-A-2002-79093, and JP-A-2002-292279. Preferred is a catalyst containing ruthenium.

  In the method for activating a catalyst for producing chlorine of the present invention, the catalyst for producing chlorine to be activated is preferably a ruthenium catalyst, particularly a catalyst containing ruthenium oxide, among the above-mentioned catalysts. The catalyst containing ruthenium oxide, for example, may be composed essentially of 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.

  In the method for activating a catalyst for producing chlorine according to the present invention, the catalyst to be activated is a catalyst for producing chlorine (deteriorated catalyst) with reduced activity. There is no particular limitation as to whether it has been reduced for various reasons. There are various reasons why the catalytic activity of the catalyst for producing chlorine used in the reaction of oxidizing hydrogen chloride with oxygen (oxidation reaction) is reduced, but usually the reaction time of the oxidation reaction (that is, the catalyst use time) The catalyst activity gradually decreases with the passage of time. In addition to this, for example, i) it becomes difficult to control the reaction temperature due to equipment troubles, etc., and the heat load when the catalyst is exposed to high temperatures for a long time, ii) oxygen due to equipment troubles, etc. Catalyst poisoning when the supply is stopped and the catalyst is in contact with hydrogen chloride for a long time in the absence of oxygen, iii) When the source gas contains sulfur (specifically, for example, oxidation The gas generated in the reaction is washed with concentrated sulfuric acid and dehydrated, and then chlorine is separated. The remaining gas is recovered and reused as a raw material gas for the oxidation reaction. (For example, when hydrogen chloride gas containing sulfur-containing impurities (such as phosgene-derived carbonyl sulfide, hydrogen sulfide, carbon disulfide, sulfur oxide, etc.) used as a by-product during the generation of the gas is used as the source gas for the oxidation reaction) Poisoning of the catalyst, iv) poisoning of the catalyst when a small amount of organic substance is contained in the raw material gas and this is not completely burned by the oxidation reaction, and v) the reaction tube and piping are used as the raw material gas and generated water Catalyst poisoning when corroded and the resulting metal adheres to the catalyst, vi) catalyst poisoning when the carrier component of the supported catalyst partially scatters and covers the active point of the catalyst, etc. May decrease.

  In the method for activating a catalyst for producing chlorine according to the present invention, a catalyst for producing chlorine (deteriorated catalyst) having reduced activity is brought into contact with an acidic solution. By performing the contact treatment in contact with the acidic liquid in this way, for example, a catalyst for chlorine production whose activity has been lowered due to heat load or catalyst poisoning can be effectively activated, and the catalytic activity can be recovered well. It is. In addition, it is speculated that the recovery of the catalyst activity is caused by the removal of the inert component soluble in the acid on the catalyst surface by the contact treatment with the acidic solution. For example, it has been confirmed by analysis that a supported catalyst having an alumina carrier is subjected to a heat load for a long time, and thus alumina partially scatters and covers the active sites. It is inferred that the alumina covering the dots is well removed.

  The acidic liquid may be, for example, an aqueous solution in which an inorganic acid such as hydrogen chloride, sulfuric acid, or nitric acid is dissolved, or an aqueous solution in which an organic acid such as acetic acid, propionic acid, butyric acid, or valeric acid is dissolved. Alternatively, an acid that is in a liquid state under the temperature and pressure at the time of contact with the deteriorated catalyst may be used alone as the acidic liquid. Among these, an aqueous solution in which an inorganic acid is dissolved is preferable from the viewpoint of washing efficiency when washing with water later. In addition, when using aqueous solution as an acidic liquid, it is preferable to use highly purified water like ultrapure water as a solvent.

  The pH of the acidic solution is preferably 5 or less, more preferably 3 or less. When the pH of the acidic liquid exceeds 5 and approaches the neutral region, the activation effect becomes insufficient, and the catalytic activity may not be sufficiently recovered.

There is no restriction | limiting in particular as a method of making a deterioration catalyst contact an acidic liquid, For example, you may carry out by a fixed bed form and may carry out by a batch batch type. When performed in a fixed bed format, the supply rate of the acidic liquid is usually about 0.01 to 100 h ⁻¹ in terms of the volume supply rate of the acidic liquid per volume of the catalyst (that is, LHSV), and the contact treatment time is Usually, it is about 0.5 to 100 hours. In the case of a fixed bed type, the acidic liquid can be circulated. On the other hand, when the batch batch method is used, the usage amount of the acidic liquid is usually about 1 to 100 parts by weight with respect to 1 part by weight of the catalyst, and the contact treatment time is usually about 0.5 to 120 hours. Moreover, when making it contact in any format, it is good that a contact processing temperature is 0-100 degreeC normally, Preferably it is 10-90 degreeC, and the frequency | count of a contact process is about 1-10 times normally.

  In the method for activating a catalyst for producing chlorine according to the present invention, it is preferable to perform further washing with water after bringing the deteriorated catalyst into contact with the acidic liquid. The amount of water used for washing with water is preferably 1 times or more, more preferably 3 times or more, the amount of the acid solution previously contacted. There is no particular limitation on the number of times of washing with water, and it is usually about 1 to 10 times, but it is preferable to carry out until it is confirmed that the pH of the waste water after washing has reached the same pH as the water used for washing. . The water used for washing is preferably water having a high purity such as ultrapure water.

  Furthermore, in the method for activating the catalyst for producing chlorine according to the present invention, drying may be performed after the deteriorated catalyst is brought into contact with the acidic solution or after washing. The drying method is not particularly limited.

  The thus activated catalyst for chlorine production exhibits excellent catalytic activity in the reaction of oxidizing hydrogen chloride with oxygen, and can be reused in such an oxidation reaction. Thereby, catalyst cost can be reduced and chlorine can be produced advantageously in terms of cost.

The chlorine production method of the present invention is a method of oxidizing hydrogen chloride with oxygen in the presence of the catalyst activated by the activation method of the present invention described above.
The reaction of oxidizing hydrogen chloride with oxygen using an activated catalyst (oxidation reaction) is usually carried out in a fixed bed reactor filled with the catalyst or a fluidized bed reactor in which the catalyst is fluidized. Gas) and oxygen (gas containing oxygen) while supplying a raw material gas under a gas phase condition. 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 gas containing hydrogen chloride is not particularly limited. For example, a gas generated by a reaction between hydrogen and chlorine, a gas generated by heating hydrochloric acid, a pyrolysis reaction or a combustion reaction of a chlorine compound, or phosgene. Use any gas containing hydrogen chloride, such as carbonylation reaction of organic compounds, chlorination reaction of organic compounds with chlorine, various by-products generated by the production of chlorofluoroalkanes, and combustion exhaust gas generated from incinerators. be able to.

  Specific examples of the various reactions described above in obtaining the gas containing hydrogen chloride include, for example, a reaction in which vinyl chloride is generated from 1,2-dichloroethane, a tetrachloromethane from tetrachloromethane as a thermal decomposition reaction of a chlorine compound. Examples of the carbonylation reaction of organic compounds with phosgene include reactions that produce isocyanates from amines and reactions that produce carbonates from hydroxy compounds. Chlorination of organic compounds with chlorine Examples of the reaction include a reaction in which allyl chloride is produced from propylene, a reaction in which ethyl chloride is produced from ethane, and a reaction in which chlorobenzene is produced from benzene. Examples of the production of chlorofluoroalkane include the production of dichlorodifluoromethane and trichloromonofluoromethane by the reaction of carbon tetrachloride and hydrogen fluoride, and dichlorodifluoromethane and trichloro by the reaction of methane, chlorine and hydrogen fluoride. For example, production of monofluoromethane.

  As the gas containing oxygen, air or pure oxygen may be used. Pure oxygen can be obtained by ordinary industrial methods such as air pressure swing method or deep cold separation.

  In the oxidation reaction, the ratio of hydrogen chloride (a gas containing hydrogen chloride) to oxygen (a gas containing oxygen) is theoretically set to 1 oxygen per mole of hydrogen chloride in order to completely oxidize hydrogen chloride to chlorine. / 4 mol is required, but usually 0.1 to 10 times the theoretical amount of oxygen is used.

In the oxidation reaction, the supply rate of the gas containing hydrogen chloride is usually about 10 to 20000 h ^{−1 in} terms of the volume supply rate of the gas per volume of the catalyst layer (0 ° C., converted to 1 atm), that is, GHSV. . On the other hand, the supply rate of the gas containing oxygen is usually about 10 to 20000 h ^{−1 in} terms of the volume supply rate of the gas per volume of the catalyst layer (0 ° C., converted to 1 atm), that is, GHSV.
Reaction conditions and the like in the oxidation reaction are not particularly limited, but 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.

  In the chlorine production method of the present invention, it is preferable to repeatedly perform the activation treatment activated by the activation method of the present invention described above and the oxidation reaction. For example, when the oxidation reaction is performed in a fixed bed format, the oxidation reaction is carried out while supplying a raw material gas consisting of hydrogen chloride and oxygen into a reactor filled with the catalyst, and the catalyst is made to the extent that it is difficult to continue the operation. When the activity of the gas is reduced, the supply of the raw material gas is stopped, and then the activation treatment is performed in a state where the catalyst is filled in the reactor, and then the supply of the raw material gas is resumed to perform the oxidation reaction, Thereafter, the activation treatment and the oxidation reaction may be repeated as necessary. On the other hand, when the oxidation reaction is performed in a fluidized bed format, while performing the oxidation reaction, a part of the catalyst is continuously or intermittently extracted from the reactor, and the activation treatment is performed in another container. Then, the catalyst is returned to the reactor, and the catalyst is circulated between the reactor and the container for the activation treatment so that the catalyst is alternately supplied to the activation treatment and the oxidation reaction.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this Example.
Hereinafter, the gas supply rate (mL / min) is shown as a converted value at 0 ° C. and 1 atm unless otherwise specified.

(Reference Example 1—Preparation of Catalyst with Reduced Activity (Deteriorated Catalyst))
First, 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 (Sakai Chemical) "CSB" manufactured by Co., Ltd .; 13.2 parts by weight of 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 ion-exchanged water was added. And kneaded. This kneaded product 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. Next, this carrier is impregnated with an aqueous solution of ruthenium chloride in an amount to give a predetermined loading rate, dried, and then fired in air at 250 ° C. for 2 hours, so that the ruthenium oxide has a loading rate of 2% by weight. A blue-gray-supported ruthenium oxide catalyst (new catalyst) supported on a carrier was obtained.

  Next, the obtained supported ruthenium oxide catalyst (new catalyst) is charged into a reactor, and an oxidation reaction is carried out over a long period of time at 280 to 390 ° C. while supplying a raw material gas containing hydrogen chloride and oxygen to the reactor. Thus, a deteriorated catalyst was prepared.

Example 1
5 g of the deteriorated catalyst obtained in Reference Example 1 and 45 g of a 36% hydrochloric acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a container, mixed, and allowed to stand at 25 ° C. for 24 hours to be brought into contact with each other. Thereafter, the supernatant liquid is removed by decantation, and the obtained solid is washed three times with 150 g of ion-exchanged water and then dried at 60 ° C. until a constant weight (2 hours or more). A catalyst activated by the activation method (activation catalyst) was obtained. In addition, it was -2.0 when pH of 36% hydrochloric acid aqueous solution used here was measured.
Next, the catalytic activity when a reaction for oxidizing hydrogen chloride with oxygen was performed using the obtained activated catalyst was evaluated by the following method. The results are shown in Table 1.

<Catalyst activity evaluation>
1 g of the obtained catalyst was filled in a nickel reaction tube having an inner diameter of 13 mm, and further 12 g of α-alumina sphere (“SSA995” manufactured by Nikkato Co., Ltd.) was filled as a preheating layer on the gas inlet side of the catalyst layer. While supplying nitrogen gas into the reaction tube at a rate of 80 mL / min, the reaction tube is immersed in a salt bath using a molten salt (potassium nitrate / sodium nitrite = 1/1 (weight ratio)) as a heat medium to form a catalyst layer. The temperature of was 281-282 ° C. Next, after the supply of nitrogen gas is stopped, hydrogen chloride gas and oxygen gas are supplied at a rate of 80 mL / min (0.21 mol / h) for hydrogen chloride gas and 40 mL / min (0.11 mol / h) for oxygen gas. The oxidation reaction was performed at a catalyst layer temperature of 281 to 282 ° C. At 1.5 hours after the start of the reaction, the gas at the outlet of the reaction tube was sampled by flowing it through a 30 wt% aqueous potassium iodide solution for 20 minutes, and the amount of chlorine produced was measured by an iodine titration method. The production rate (mol / h) of was determined. From the chlorine production rate and the hydrogen chloride supply rate (mol / h), the conversion rate (%) of hydrogen chloride was calculated by the following equation.

Hydrogen chloride conversion (%)
= [Chlorine production rate (mol / h) × 2 ÷ hydrogen chloride supply rate (mol / h)] × 100

(Example 2)
Instead of the 36% hydrochloric acid aqueous solution used in Example 1, 45 g of 20% hydrochloric acid aqueous solution (prepared by diluting 25 g of 36% hydrochloric acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) with 20 g of ion-exchanged water) was used. Except for this, a catalyst (activated catalyst) activated by the activation method of the present invention was obtained in the same manner as in Example 1. In addition, it was -1.7 when pH of the 20% hydrochloric acid aqueous solution used here was measured.
Next, the catalytic activity when the reaction for oxidizing hydrogen chloride with oxygen was performed using the obtained activated catalyst was evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
In place of the 36% hydrochloric acid aqueous solution used in Example 1, prepared by diluting 3.125 g of a 2.5% aqueous hydrochloric acid solution (36% hydrochloric acid aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) with 41.875 g of ion-exchanged water. Except for using 45 g, a catalyst (activated catalyst) activated by the activation method of the present invention was obtained in the same manner as in Example 1. The pH of the 2.5% aqueous hydrochloric acid solution used here was 0.2.
Next, the catalytic activity when the reaction for oxidizing hydrogen chloride with oxygen was performed using the obtained activated catalyst was evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 1)
The catalytic activity when the reaction of oxidizing hydrogen chloride with oxygen was performed using the deteriorated catalyst obtained in Reference Example 1 was evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
5 g of the deteriorated catalyst obtained in Reference Example 1 and 45 g of ion-exchanged water were mixed in a container, and the mixture was allowed to contact at 25 ° C. for 24 hours. Thereafter, the supernatant is removed by decantation to obtain a solid. Subsequently, the solid is again put into a container together with 45 g of ion-exchanged water, left at 25 ° C., and the supernatant is removed by decantation. Repeated several times. At this time, the standing time was 24 hours for the first time and 72 hours for the second time. Then, it dried until it became constant weight at 60 degreeC (2 hours or more), and the catalyst which carried out water treatment was obtained.
Next, the catalytic activity when the reaction of oxidizing hydrogen chloride with oxygen was performed using the obtained catalyst was evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 3)
1 g of the deteriorated catalyst obtained in Reference Example 1 was filled in a nickel reaction tube having an inner diameter of 13 mm, and 12 g of α-alumina sphere (“SSA995” manufactured by Nikkato Co., Ltd.) was used as a preheating layer on the gas inlet side of the catalyst layer. Filled. While supplying nitrogen gas into the reaction tube at a rate of 80 mL / min, the reaction tube is immersed in a salt bath using a molten salt (potassium nitrate / sodium nitrite = 1/1 (weight ratio)) as a heat medium to form a catalyst layer. The temperature of was set to 350 ° C. Next, after the supply of nitrogen gas was stopped, carbon monoxide gas and nitrogen gas were supplied at a rate of 3.2 mL / min (0.009 mol / h) for carbon monoxide gas and 28.8 mL / min for nitrogen gas ( 0.08 mol / h) was supplied and kept at 350 ° C. for 2 hours to perform contact treatment with a reducing gas.

  Subsequently, the contact treatment with the oxidizing gas was performed following the contact treatment with the reducing gas. That is, after the supply of carbon monoxide gas is stopped, oxygen gas and nitrogen gas are supplied at a rate of 40 mL / min (0.009 mol / h) for oxygen gas and 160 mL / min (0.43 mol / h) for nitrogen gas. The catalyst was subjected to contact treatment with an oxidizing gas by maintaining at 350 ° C. for 2 hours, and a catalyst subjected to contact treatment with an oxidizing gas after contact treatment with a reducing gas was obtained.

  Next, without removing the obtained catalyst from the reaction tube, the catalytic activity when the reaction of oxidizing hydrogen chloride with oxygen was performed following the contact treatment with the oxidizing gas was evaluated. That is, the supply of oxygen gas was stopped, the supply rate of nitrogen gas was set to 80 mL / min (0.21 mol / h), and then the temperature of the catalyst layer was set to 281 to 282 ° C. Subsequently, after the supply of nitrogen gas was stopped in the same manner as the catalyst activity evaluation in Example 1, hydrogen chloride gas and oxygen gas were supplied to perform an oxidation reaction, and the amount of chlorine produced was measured. The hydrogen conversion (%) was calculated. The results are shown in Table 1.

Claims (5)

  A method for activating a catalyst for producing chlorine used in a reaction for oxidizing hydrogen chloride with oxygen, comprising bringing a catalyst for producing chlorine having reduced activity into contact with an acidic solution.   The method for activating a catalyst for chlorine production according to claim 1, wherein the acidic solution has a pH of 5 or less.   The method for activating a catalyst for chlorine production according to claim 1 or 2, wherein the acidic liquid is an aqueous solution in which an inorganic acid is dissolved.   The method for activating a catalyst for chlorine production according to claim 1, wherein the catalyst for chlorine production is a catalyst containing ruthenium oxide.   A method for producing chlorine in which hydrogen chloride is oxidized with oxygen in the presence of a catalyst, wherein the catalyst is a catalyst activated by the activation method according to claim 1. Production method.