JPH08155305A - Method for regenerating catalyst and production of trichloroethylene using the same - Google Patents

Abstract

PURPOSE: To easily and sufficiently regenerate a degraded catalyst by specifying the contents by weight of a group IV metal of Periodic Table and a platinum group metal and heating the degraded catalyst to a specified temp. in an oxygen-containing gas stream. CONSTITUTION: In this method for regenerating a degraded catalyst whose catalyst is obtained by depositing at least one metal selected from the group IV metals of the Periodic Table of the Elements and at least one metal selected from the platinum group metals on activated carbon, the contents of the group IV metal and the platinum group metal of the catalyst are adjusted to 0.1 to 50wt.% and 0.01 to 10wt.% based on 100wt.% of the catalyst weight respectively and the degraded catalyst is heated to 100 to 250 deg.C in an oxygen-containing gas stream. Examples of the group IV metals are Cu, Ni, Zn, Cr, Mn, Fe, Co and examples of the platinum group metals are Pt, Pd, Rh, Ir, Ru and Os. Thus, the degraded catalyst can effectively be regenerated by performing the simple treatment which comprises only heating the degraded catalyst to a temp. within a specified range in a specific atmosphere.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of regenerating a catalyst in which a specific metal element is supported on activated carbon by heating in a specific atmosphere in a predetermined temperature range, and a method of regenerating the catalyst into tetrachloroethylene. The present invention relates to a method for producing trichlorethylene by hydrodehydrochlorination of methane.

[0002]

2. Description of the Related Art Tetrachloroethylene is produced as a by-product in the production process of trichlorethylene and its use is limited. On the other hand, trichlorethylene is widely used as a solvent and the like for washing and removing rust preventive oil and the like on the metal surface, and recently, it is a useful compound which is also used as a raw material for an alternative CFC.

Conventionally, as a method for synthesizing trichlorethylene by hydrodehydrochlorinating tetrachloroethylene, copper chloride and a chloride of a platinum group element are supported on activated carbon as a catalyst, and hydrogenated in a hydrogen stream. A method is known (DE No. 2819209). However, this method has a problem that the catalyst life is short, and efforts have been made to extend the catalyst life. For example, by adding triphenylphosphine or the like to a catalyst in which copper chloride and a chloride of a platinum group element are supported on activated carbon, the catalyst life could be extended to some extent (DE No. 3804265), but to a satisfactory degree. No improvement in catalyst life has been obtained.

On the other hand, in the present invention, the activated carbon used as a catalyst carrier is used as a physical adsorbent in a regeneration method in an oxygen-containing air stream at 300 to 700 ° C.
A method of heat treatment is known, but in the present invention, when treated by this method, it cannot be used because activated carbon burns. In addition, a method of regenerating at 800 to 1000 ° C. in a steam or carbon dioxide-containing air flow is also known,
The reaction in the process of regeneration is said to be an endothermic reaction, and it is usually necessary to raise the temperature to 800 ° C. or higher. In any case, these are methods for regenerating the activated carbon used as the adsorbent, which is in a different technical field from the method for regenerating the supported catalyst of the present invention.

[0005]

In view of the above circumstances, the present invention is a method for producing trichlorethylene by hydrodehydrochlorination of tetrachloroethylene, which is a method for easily and sufficiently regenerating a deteriorated catalyst. ,
Another object of the present invention is to provide a method for producing trichlorethylene at low cost by using a long-life catalyst regenerated by the method.

[0006]

The method for regenerating a catalyst according to the first aspect of the present invention comprises at least one metal selected from the fourth period metals of the periodic table of elements and at least one metal selected from the platinum group metals. In a method of regenerating a catalyst in which a metal and activated carbon are supported, when the catalyst is 100% by weight,
The periodic metal is 0.1 to 50% by weight, the platinum group metal is 0.01 to 10% by weight, and the catalyst is heated in an oxygen-containing gas stream at 100 to 250 ° C.

The method of regenerating the catalyst of the second invention is the first method.
The atmosphere for catalyst regeneration of the invention is steam and / or carbon dioxide, and the treatment temperature is 300 to 1000 ° C. Furthermore, the third and fourth inventions are characterized in that the catalyst regenerated by the method of the first and second inventions is used in the step of producing tetrachlorethylene by heating tetrachloroethylene in the presence of hydrogen.

As a catalyst for producing trichlorethylene by hydrodehydrochlorination of tetrachloroethylene, 0.1 to 50% by weight of a fourth period metal and 0.01 to 10% by weight of a platinum group metal are supported on activated carbon. The above catalyst is optimal in terms of reactivity and trichloroethylene selectivity. Further, this catalyst may be used after being subjected to a heat reduction treatment in a hydrogen stream as a pretreatment. Further, in the above catalyst, the life of the catalyst can be extended by adding an alkali metal such as potassium, rubidium, cesium or phosphine, but the method for regenerating the catalyst of the present invention is also applicable to the catalyst to which these elements are added. obtain.

Examples of the "fourth period metal" in the Periodic Table of Elements include Cu, Ni, Zn, Cr, Mn, Fe and Co, and examples of the "platinum group metal" include Pt and P.
d, Rh, Ir, Ru and Os. The fourth period metal and the platinum group metal may be used alone or in combination of two or more. Among the above metals, as the fourth period metal, as in the fifth to sixth inventions, Cu
And / or a combination of Ni, especially Cu, and Pt as a platinum group metal is more preferable because the reaction rate is high and the selectivity of trichlorethylene is high.

When the total amount of the catalyst including activated carbon is 100% by weight, the content of the fourth period metal is "0.
1 to 50% by weight, particularly preferably 0.5 to 10% by weight
Is. If the content is less than 0.1% by weight, a good catalytic action is not exhibited, and even if the supported amount is more than 50% by weight, no further effect can be obtained. Further, the content of the platinum group metal is "0.01 to 10% by weight", and particularly preferably 0.03 to 3% by weight. This content is 0.
If it is less than 01% by weight, good catalytic action is not exhibited and 1
Even if the supported amount is large, exceeding 0% by weight, no further effect can be obtained.

The shape of the above-mentioned catalyst is not particularly limited, and it can be arbitrarily selected depending on the type of reaction such as liquid phase reaction, gas phase reaction or the structure of the reaction tank, and powder form,
Alternatively, a shape such as a granular shape, a spherical shape, a cylindrical shape, or a tubular shape, which is a molded body, may be mentioned. Further, the above catalyst can be used by mixing with an inert filler such as glass beads. Further, as a method for supporting the metal on the activated carbon, a known method can be adopted without any limitation, but it is usually carried out by an impregnation method, a coprecipitation method or the like.

When the above catalyst is used for the production of trichlorethylene, the yield of trichlorethylene decreases with the passage of reaction time. Therefore, it is reproduced by the method of the first or second invention. The regeneration of the catalyst in the "in air containing oxygen" of the first invention is promoted by heating,
The regeneration temperature is in the range of “100 to 250 ° C.”, and particularly preferably 190 to 230 ° C.

When the regeneration temperature is less than 100 ° C., the catalyst is not sufficiently regenerated and the catalyst life is not so long. On the other hand, when the upper limit is 250 ° C., the purpose of the catalyst regeneration is sufficiently achieved, and higher temperatures are required. You don't have to. Also, 250
If the temperature exceeds ℃, there is a risk of causing oxidation, combustion, etc. Further, when the regeneration temperature is in the range of 190 to 230 ° C., the effect of catalyst regeneration is great and there is no possibility of causing combustion or the like. The pressure during regeneration of the catalyst is preferably 0.1 to 30 kg / cm ² (absolute pressure) from the viewpoint of safety,
From the economical aspect, the range of 1 to 10 kg / cm ² (absolute pressure) is more preferable. The heating time of the catalyst depends on the heating temperature, but is preferably 3 to 100 hours. If it is shorter than 3 hours, it cannot be said that the regeneration is sufficient, and if it exceeds 100 hours, it is not economically advantageous.

As the oxygen-containing air stream, it is preferable to use an air stream containing about 1 to 80% by weight of oxygen, and it is optimal to use air as it is. Examples of the gas containing oxygen include a mixed gas of oxygen and an inert gas such as nitrogen, steam, carbon dioxide, hydrogen chloride and the like. In order to suppress rapid heat generation, depending on conditions such as the regeneration temperature, an inert gas such as nitrogen, a gas such as water vapor, carbon dioxide, and hydrogen chloride is mixed with, for example, air to dilute oxygen to reduce the temperature. It may be used by gradually changing it from a high concentration to a high concentration. If the oxygen content in the oxygen-containing stream is less than 1% by weight, the catalyst regeneration effect is not sufficient, and even if treated in a stream containing a large amount of oxygen exceeding 80% by weight, no further regeneration effect can be obtained. However, it is not preferable because it is dangerous.

As described above, the reason why the regeneration of the catalyst by oxygen proceeds at a temperature as low as unthinkable in the prior art is that the catalyst used in the present invention has a catalytic action for hydrogenation reaction and It is thought that this is because it also acts as a catalyst for the oxidation reaction, and therefore the upper limit is 250 ° C.
It can be regenerated sufficiently in the temperature range of
It is considered that combustion may occur above this upper limit temperature.

The regeneration in "in the steam and / or carbon dioxide stream" of the second invention is promoted by heating, and the regeneration temperature is in the range of "300 to 1000 ° C". The regeneration temperature is preferably in the range of 300 to 800 ° C, particularly 400 to 600 ° C. When the regeneration temperature is lower than 300 ° C, the catalyst is not sufficiently regenerated and the catalyst life is not so long. On the other hand, when the upper limit is 1000 ° C, the purpose is sufficiently achieved and it is not necessary to raise the temperature any higher. Further, at a temperature exceeding 1000 ° C., there is a possibility that oxidation, combustion, etc. may occur due to the same reason as in the case of the first invention.

When the regeneration temperature is 300 to 800 ° C., particularly 400 to 600 ° C., the effect of catalyst regeneration is sufficiently obtained and there is no fear of causing combustion. Further, the pressure during regeneration of the catalyst is preferably 0.1 to 30 kg / cm ² (absolute pressure) from the viewpoint of safety, as in the case of the first invention, and 1 to 10 kg / c from the economical point of view.
The range of m ² (absolute pressure) is more preferable. The heating time of the catalyst depends on the heating temperature, but is preferably 3 to 100 hours for the same reason as in the first invention.

The steam and / or carbon dioxide-containing air stream may be an air stream of which the total amount is steam and / or carbon dioxide. Further, depending on the conditions such as the regeneration temperature, an inert gas such as nitrogen or the like. A gas obtained by mixing a gas such as hydrogen and diluting it may be used. The gas mixed for dilution is preferably up to about 50% by weight, and if diluted more than that, it takes too much time to regenerate the catalyst, which is not efficient. In particular, it is preferable not to mix oxygen, except for oxygen which is unavoidably mixed. Furthermore,
The water vapor and carbon dioxide may be used alone, or both gases may be used in combination, and other gas such as nitrogen may be further mixed and used.

The production of trichlorethylene according to the third and fourth inventions can be carried out by any reaction method such as a continuous method or a batch method, and it is usually carried out by a gas phase reaction, but also by a liquid phase reaction. Alternatively, the reaction may be carried out in the state where the gas phase and the liquid phase coexist. Further, any of a fixed bed, a fluidized bed, a moving bed and the like may be used. Further, the trichloroethylene obtained by the above-mentioned production method can be separated and recovered by any of various methods such as distillation and adsorption separation, or by a combination thereof, and the unreacted raw material components may be recycled for use. it can.

The contact time "W / F (sec)" between the catalyst and the tetrachloroethylene used for the reduction reaction by hydrodehydrochlorination is preferably 0.1 to 1000 sec, and 0.5 to 50 sec. Is more preferable. If the contact time is less than 0.1 sec, tetrachloroethylene cannot be effectively reduced to trichlorethylene, and if it exceeds 1000 sec, the effect commensurate with the increase in the amount of catalyst may not be expected. However, W (cc): volume of catalyst layer F (cc / sec): supply amount of tetrachloroethylene

[0021]

The present invention will be described in more detail with reference to the following examples. The catalyst was regenerated by using the catalyst deteriorated by the forced deterioration test. Example 1 (1) Forced deterioration test of catalyst Activated carbon having 5% by weight of Cu and 0.125% by weight of Pt supported on a reaction tube (Pyrex glass "registered trademark of Dow Corning"; 30 mmφ x 500 mmL) (Cylindrical shape; 3 mmφ × 5 mmL) 25 cc was filled, and at a reaction temperature of 340 ° C., tetrachloroethylene: hydrogen =
1: 1.25 (molar ratio), and W / F (contact time) 7.
6 sec. Was continuously supplied under the conditions of, and the reaction was carried out for 6 hours.

After the completion of the reaction, the mixture of the reaction product flowing out from the reaction tube and the unreacted raw material was analyzed by gas chromatography and the like. As a result, the conversion rate of tetrachloroethylene 1 hour after the start of the reaction was 75.9 mol% (hereinafter ,% Are all mol%), and the selectivity of trichlorethylene was 90.6%. In addition, the conversion rate of tetrachloroethylene after 6 hours from the start of the reaction was 45.1%, and the selectivity of trichlorethylene was 66.7%. A chlorinated hydrocarbon having two carbon atoms was confirmed as a by-product.
The conversion rate of tetrachloroethylene, the selectivity of trichlorethylene, and the production rate of trichlorethylene were calculated based on the following formulas.

(1) Conversion rate of tetrachloroethylene (%)
= 100- (unreacted tetrachloroethylene amount / total distillate amount) × 100 (2) trichlorethylene selectivity (%) = {trichloroethylene production amount / (total distillate amount-unreacted tetrachloroethylene amount)} × 100 ( 3) Trichlorethylene production rate (g / hr-catalyst 1
Liter) = amount of trichlorethylene produced per hour / volume of catalyst layer In the above (1) and (2), the unit of quantity is mol, and in (3), g.

(2) Regeneration of catalyst and production of trichlorethylene using regenerated catalyst (1) After the deterioration test of 6 hours was continued for 6 hours, the catalyst was regenerated by heating at 200 ° C. for 15 hours in an air stream. Using the catalyst, the reduction reaction of tetrachloroethylene was performed again for 6 hours in the same manner as in (1) above. As a result, the conversion rate of tetrachloroethylene 1 hour after the start of the reaction was 50.6%,
The selectivity of trichlorethylene was 94.9%.

Example 2 Regeneration was carried out in the same manner as in Example 1 except that the catalyst forcibly deteriorated in the same manner as in Example 1 was used, the temperature of the air stream was 170 ° C., and the heating time was 6 hours. It was Then, using this regenerated catalyst, a reduction reaction of tetrachloroethylene was performed again in the same manner as in Example 1. As a result, the conversion rate of tetrachloroethylene 1 hour after the start of the reaction was 46.
9%, the selectivity of trichlorethylene is 72.3%
Met.

Example 3 The catalyst was forcibly deteriorated in the same manner as in Example 1 except that the reaction temperature was 300 ° C. and the reaction time was 24 hours. After the reaction was completed, the mixture of the reaction product flowing out from the reaction tube and the unreacted raw material was analyzed by gas chromatography or the like, and as a result, the conversion rate of tetrachloroethylene 1 hour after the start of the reaction was 92.8%. Rate is 8
It was 0.5%. In addition, the conversion rate of tetrachloroethylene 24 hours after the start of the reaction was 25.9%, and the selectivity of trichlorethylene was 87.3%. A chlorinated hydrocarbon having two carbon atoms was confirmed as a by-product.

After the above reaction was continued for 24 hours, the catalyst was heated in a steam-containing stream [steam: nitrogen = 94: 6 (weight ratio)] at 500 ° C. for 6 hours to be regenerated. The reduction reaction was performed again in the same manner as in Example 1 except that the temperature was 300 ° C. As a result, the conversion rate of tetrachloroethylene one hour after the start of the reaction was 58.3%, and the selectivity of trichlorethylene was 85.9%.

Example 4 The catalyst was forcibly deteriorated in the same manner as in Example 1 except that the reaction temperature was 350 ° C. After the reaction was completed, the mixture of the reaction product flowing out from the reaction tube and the unreacted raw material was analyzed by gas chromatography and the like, and as a result, the conversion rate of tetrachloroethylene 1 hour after the start of the reaction was 98.6%. The rate was 61.5%. Also,
The conversion rate of tetrachlorethylene 6 hours after the start of the reaction is 2
It is 9.3%, and the selectivity of trichlorethylene is 14.
It was 0%. A chlorinated hydrocarbon having two carbon atoms was confirmed as a by-product.

After the reaction was continued for 6 hours, the catalyst was regenerated by heating it in the same steam flow as in Example 3 at 800 ° C. for 6 hours, and using this catalyst, the reaction temperature was 350 ° C. The reduction reaction was performed again in the same manner as in Example 1. As a result, the conversion rate of tetrachloroethylene one hour after the start of the reaction was 41.7%, and the selectivity of trichlorethylene was 45.1%.

Example 5 The catalyst was forcibly deteriorated in the same manner as in Example 1 except that the reaction temperature was 350 ° C. After completion of the reaction, the mixture of the reaction product flowing out from the reaction tube and the unreacted raw material was analyzed by gas chromatography or the like, and as a result, the conversion rate of tetrachloroethylene 1 hour after the start of the reaction was 97.0%, and the selection of trichloroethylene was selected. The rate was 63.5%. Also,
The conversion rate of tetrachlorethylene 6 hours after the start of the reaction is 2
It is 5.3%, and the selectivity of trichlorethylene is 29.
It was 0%. A chlorinated hydrocarbon having two carbon atoms was confirmed as a by-product.

After the above reaction was continued for 6 hours, the catalyst was heated in a carbon dioxide stream at 600 ° C. for 6 hours to be regenerated, and the reaction temperature was changed to 350 ° C. using this catalyst.
The reduction reaction was performed again in the same manner as in. As a result, the conversion rate of tetrachloroethylene 1 hour after the start of the reaction was 41.3.
%, And the selectivity for trichlorethylene was 65.2%. The results of Examples 1 to 5 are shown in Table 1 above.

[0032]

[Table 1]

From the results shown in Table 1, it can be seen that, in each of the examples, the conversion rate and the selectivity were improved by the regeneration process in any case. In particular, the recovery rates in Examples 4 to 5 in which the catalyst deterioration is severe are very large. Further, it can be seen that in Example 3 where there is almost no decrease in selectivity, the selectivity is not significantly changed, but the conversion rate is greatly improved and the yield is also significantly increased. Furthermore, in Examples 1 and 2 in which the same deteriorated catalyst was regenerated under different conditions,
It can be seen that the degree of recovery of the conversion rate and the selectivity of Example 1 is higher, and the effect of the regeneration treatment at high temperature for a long time is greater.

Comparative Example 1 A catalyst was tried to be regenerated in the same manner as in Example 1 except that the catalyst forcibly deteriorated in the same manner as in Example 1 was used and the temperature of the air flow was set to 260 ° C. As a result, the catalyst oxidizes and burns,
It became powdery and the weight was about 1/3 of the initial weight, so that it could not be used as a catalyst.

Comparative Example 2 An attempt was made to regenerate the catalyst in the same manner as in Example 3 except that the catalyst forcibly deteriorated in the same manner as in Example 1 was used and the temperature of the steam flow was set to 1100 ° C. As a result, the catalyst was oxidized and burned into powder, which was unusable as a catalyst.

The reproducing method of the present invention is not limited to the ones shown in the above specific examples, but can be applied to various fields within the scope of the present invention. For example, the catalyst used in the production of trichlorethylene of the present invention can be used generally in the reduction reaction of chlorinated hydrocarbons, and as one specific example, in the case of producing monochlorobenzene from dichlorobenzene. It is also useful for regeneration of catalysts used for hydrogenation of other chlorinated hydrocarbons.

[0037]

According to the catalyst regeneration methods of the first and second aspects of the invention, the deteriorated catalyst can be effectively regenerated by a simple treatment of heating in a specific atmosphere and in a specific temperature range. . In addition, in the third and fourth inventions, trichloroethylene can be produced at a low cost with a sufficient catalyst life by incorporating the above-mentioned regeneration method into the method for producing trichlorethylene by hydrodehydrochlorination of tetrachloroethylene. Furthermore, the fifth and sixth
When a catalyst carrying a specific metal is used as in the invention, the effect of the regeneration method of the present invention is sufficiently exhibited.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location // C07B 61/00 300 (72) Inventor Teruo Yoshida 1 Funami-cho, Minato-ku, Nagoya-shi, Aichi 1 Inside Nagoya Research Institute, Toagosei Co., Ltd.

Claims (6)

[Claims] 1. A method of regenerating a catalyst in which at least one metal selected from the fourth period metals of the periodic table of elements and at least one metal selected from a platinum group metal are supported on activated carbon, When the catalyst is 100% by weight,
The fourth period metal is 0.1 to 50% by weight, the platinum group metal is 0.01 to 10% by weight, and the catalyst is heated in an oxygen-containing gas stream at 100 to 250 ° C. And a method for regenerating the catalyst. 2. A method for regenerating a catalyst in which at least one metal selected from the fourth period metals of the Periodic Table of Elements and at least one metal selected from platinum group metals are supported on activated carbon, When the catalyst is 100% by weight,
The fourth period metal is 0.1 to 50% by weight, the platinum group metal is 0.01 to 10% by weight, and the catalyst is 300 to 1 in a steam and / or carbon dioxide-containing stream.
A method for regenerating a catalyst, which comprises heating at 000 ° C. 3. A catalyst in which at least one metal selected from the fourth period metals of the periodic table of the elements and at least one metal selected from platinum group metals are supported on activated carbon,
In the method for producing trichlorethylene by heating tetrachloroethylene in the presence of hydrogen, the catalyst is mixed with 10
When it is 0% by weight, the fourth period metal is 0.1 to 5
0% by weight, the platinum group metal is 0.01 to 10% by weight, and the catalyst is 100 to 25% in an oxygen-containing gas stream.
A method for producing trichlorethylene, which is regenerated by heating at 0 ° C. 4. A catalyst comprising activated carbon carrying at least one metal selected from the fourth period metals of the Periodic Table of Elements and at least one metal selected from the platinum group metals,
In the method for producing trichlorethylene by heating tetrachloroethylene in the presence of hydrogen, the catalyst is mixed with 10
When it is 0% by weight, the fourth period metal is 0.1 to 5
0% by weight, the platinum group metal is 0.01 to 10% by weight, and the catalyst is heated at 300 to 1000 ° C. in a steam and / or carbon dioxide-containing gas stream,
A method for producing trichlorethylene, which is regenerated. 5. The method for regenerating a catalyst according to claim 1, wherein at least one kind of metal selected from the fourth period metals of the periodic table of elements is copper and / or nickel. 6. The method for producing trichlorethylene according to claim 3 or 4, wherein at least one metal selected from the 4th period metals in the periodic table of elements is copper and / or nickel.