JPH03275149A - Method for regenerating catalyst for production of unsaturated diester - Google Patents

Abstract

PURPOSE:To effectively and efficiently regenerate a deactivated catalyst by simple operation by alternately subjecting the catalyst to oxidation treatment with a gas contg. molecular oxygen and reduction treatment with a reducing gas and further subjecting the treated catalyst to halogenation treatment. CONSTITUTION:When a deposited Pd-contg. catalyst for production of unsatd. diester is regenerated, the deactivated catalyst is alternately subjected to oxidation treatment at 100-600 deg.C with a gas contg. molecular oxygen and reduction treatment at 100-600 deg.C in an atmosphere of a reducing gas such as hydrogen or alcohol. The treated catalyst is further subjected to halogenation treatment at 100-300 deg.C in a flow of a gas contg. carboxylic acid and a halogen-contg. compd. The deteriorated catalyst is effectively and efficiently regenerated by simple operation.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for regenerating a catalyst for producing an unsaturated diester, and more specifically, the present invention relates to a method for regenerating a catalyst for producing an unsaturated diester. This invention relates to a method for regenerating a supported palladium-based catalyst, which is used in the production of unsaturated diesters and whose activity has decreased, to high activity by conducting a flow reaction.

[Prior art and the problem to be solved by the invention] Unsaturated glycol diester (i.e., unsaturated diester) is produced by reacting a conjugated diene, a carboxylic acid, and molecular oxygen.
It is known that palladium-based catalysts are effective in producing .

For example, Japanese Patent Publication No. 57-51375, Japanese Patent Publication No. 53
No. 15488 and Japanese Patent Publication No. 53-15490 disclose that palladium and antimony, or supported palladium-based catalysts containing palladium, antimony, and vanadium as essential metal components, have extremely high activity as catalysts for producing unsaturated diesters. is shown.

In addition, if an alkali metal carboxylate or an alkali metal halide is further supported as an activity-promoting component on the supported palladium-based catalyst containing the above-mentioned essential metal components, the activity will be higher and the life will be longer. It has also been shown that industrially excellent catalysts can be obtained.

However, even with such a catalyst, it is inevitable that its activity will gradually decrease when used for a long time.

There are various possible causes for this decrease in catalyst activity, but the main cause is believed to be the accumulation of carbonaceous matter on the catalyst surface I\. Other causes are assumed to be sinterlinking of palladium and other metal components of the catalyst, and fluctuations in valence caused by oxygen in the reaction gas.

In general, as a method for regenerating a noble metal catalyst whose activity has decreased, the deactivated catalyst is oxidized with molecular oxygen at a temperature in the range of 100 to 6006 C, carbon-based deposits on the catalyst are incinerated, and the precious metal is removed. to the oxide of the metal,
Next, there is a method of reducing the oxide to return it to a metallic state.

However, such an in-shell regeneration treatment method is not suitable for catalysts for producing palladium-based unsaturated diesters that use alkali metal carboxylates or alkali metal halides with them as activity-promoting components. . That is, in regenerating such a catalyst, the above-mentioned -
When oxidation and reduction are repeated at high temperatures as in the in-shell regeneration treatment method, part or all of the alkali metal compound, which is an activity-promoting component, transforms into an alkali metal or the like and remains on the catalyst surface. Altered substances such as residual alkali metals of this kind do not exhibit sufficient activity promoting action, or rather act as catalyst poisons.

Therefore, general regeneration treatment methods for precious metal catalysts cannot be applied as is to such catalysts.

Therefore, conventional methods for regenerating supported palladium-based unsaturated diester production catalysts containing such alkali metal compounds as activity-promoting components include: ℃ treatment method (see Japanese Patent Publication No. 55-33660); ■ After cleaning and removing activity-promoting components from the deactivated catalyst using water and/or alcohol, under an oxygen-containing gas atmosphere. , a method has been proposed in which oxidation treatment is performed at a temperature in the range of 100 to 500°C, followed by reduction treatment at a temperature in the range of 100 to 500°C, and the activity-promoting component is supported again.

These regeneration methods are either effective to some extent or have their own problems in regenerating palladium-based catalysts in which alkali metal carboxylates or alkali metal halides are added and supported as activity-promoting components. .

That is, the regeneration method using steam treatment described in (1) above seems to be effective for removing high-boiling substances that adhere to the catalyst surface so as to cover the active sites. In other words, for catalysts with relatively mildly decreased activity that still have approximately 50% or more activity remaining, based on the highest activity value at the beginning of the reaction, it actually exerts a remarkable regeneration effect, and the initial activity value is reduced. It can be said that it will be almost completely restored. However, the residual rate of catalyst activity is about 50
% or less, the regeneration effect is insufficient and the activity cannot be fully restored, and of course cannot be completely restored to the initial activity. Further, even if there is a slight decrease in activity with a residual rate of catalytic activity of about 50% or less, if the reaction regeneration treatment is repeated, the regeneration effect will decrease each time the regeneration is repeated.

It is thought that these problems occur because, even when treated with a gas containing water vapor, substances with higher boiling points that cannot be removed remain on the catalyst and gradually accumulate.

On the other hand, the regeneration method described in (1) above by washing and removing the activity-promoting component remaining on the deactivated catalyst, oxidation treatment, reduction treatment, and re-supporting the activity-promoting component is: (1) The operation is very complicated; Elution of metal components is likely to occur; ■During cleaning, alkali metal halides, which are activity-promoting components, may cause corrosion of equipment such as reactors; ■Recovery and replenishment of activity-promoting components is costly, etc. There are problems.

In particular, the problem (2) above means that not only is it impossible to restore the activity due to the loss of essential catalytic metal components from the catalyst, but also that the catalytic activity is irreversibly lost each time it is regenerated. As a result, a serious problem arises in that the usable period of the catalyst due to the reaction-regeneration cycle is shortened.

The present invention has been made in view of the above circumstances.

The purpose of the present invention is to solve the above-mentioned problems and to provide a method for producing unsaturated diesters (unsaturated glycol diesters) by gas-phase flow oxidative acyloxylation reaction of conjugated dienes with carboxylic acids, in which alkali metals are used as activity-promoting components. As a method for regenerating a supported palladium-based catalyst containing a carboxylic acid salt or an alkali metal halide, a catalyst that can effectively and efficiently regenerate a deteriorated catalyst with a simple operation is used. The object of the present invention is to provide an industrially excellent method for regenerating a catalyst for producing saturated diesters.

[Means for Solving the Problems] The present inventors have developed a supported palladium-based catalyst (catalyst for producing unsaturated diesters) on which an alkali metal carboxylate or an alkali metal halide is supported as an activity promoting component. ) As a result of extensive research into regeneration treatment methods, we have found that by sequentially treating the deactivated catalyst according to a series of specific steps, the deactivated catalyst can be compared to the original catalyst in terms of activity and selectivity. It was discovered that the same performance can be achieved, and the present invention was completed based on this knowledge.

That is, the invention according to claim 1 is a catalyst used in a method for producing an unsaturated diester by reacting a mixed gas containing a conjugated diene, a carboxylic acid, and molecular oxygen by a gas phase flow method, When regenerating a supported palladium-based catalyst in which an alkali metal carboxylate or an alkali metal halide is supported as an activity-promoting component, the catalyst with decreased activity is heated to 100% by using a gas containing molecular oxygen. A heat treatment step in which an oxidation treatment is performed at a temperature in the range of ~600°C and a reduction treatment is performed in a reducing gas atmosphere at a temperature in the range from 100 to 600°C; A halogenation treatment step of treating the obtained catalyst in a gas stream containing a carboxylic acid and a halogen-containing compound at a temperature in the range of 100 to 300°C. The invention according to claim 2 is a regeneration method, and the invention according to claim 2 relates to the method for regenerating the catalyst for producing an unsaturated diester according to claim 1, wherein the catalyst contains palladium, antimony and vanadium, and the invention according to claim 3 The invention relates to a method for regenerating a catalyst for producing an unsaturated diester according to claim 1 or 2, in which the heat treatment step is performed by the reduction treatment, the oxidation treatment 1. The invention according to claim 4 relates to a method for regenerating a catalyst for producing an unsaturated diester according to any one of claims 1 to 3, in which the heat treatment step is performed in the order of the reduction treatment, and the invention according to claim 4 relates to a method for regenerating the catalyst for producing an unsaturated diester according to any one of claims 1 to 3. It is carried out in the presence of a gas that

The method of the present invention will be explained in detail below.

The reaction to obtain an unsaturated diester (unsaturated glycol diester) by subjecting a conjugated diene, a carboxylic acid, and molecular oxygen to a gas phase flow reaction is generally carried out by the following formula (wherein R1-R6 in formula [1] , each independently represents a hydrogen atom or a hydrocarbon group such as a lower alkyl group, and may be the same or different, and R7
represents a hydrocarbon group such as a lower alkyl group. ) consists of the main reaction expressed as

In the oxidative acyloxylation reaction of a conjugated diene with a carboxylic acid using the supported palladium-based catalyst according to the method of the present invention, the so-called 1, Most of the reactions are 4-addition type reactions, but addition type reactions to other positions (for example, 1,2-addition type reactions) are also very rare or occur together.

For example, when butadiene is used as the conjugated diene and acetic acid is used as the carboxylic acid, 1,4-diacetoxybutene-2 according to the above formula [I] is the main product, and at the same time a trace amount of 1,2-diacetoxybutene-2 is produced. Diacetoxybutene-3 etc. are produced.

In the catalyst regeneration method of the present invention, the catalyst to be regenerated is a carrier containing an alkali metal carboxylate or an alkali metal halide as an activity promoting component for producing an unsaturated diester by the gas phase flow reaction. Although there are no particular limitations on the type of palladium-based catalyst as long as the activity is reduced or deactivated, the reaction described above (the reaction that produces an unsaturated diester from a conjugated diene, a carboxylic acid, and molecular oxygen) is preferable. ), particularly preferably a catalyst which is used in the reaction of producing diacetoxy-2-butene from butadiene, acetic acid and molecular oxygen by gas phase flow reaction, and whose catalytic activity is reduced or deactivated.

In addition to the carrier component, this supported palladium-based catalyst contains at least palladium as a catalytic metal component. ■Va group such as (vanadium), Vla group such as Cr, Mo, ■a group such as Mn,
■a group such as Co, Ni, nb group such as Zn, B (boron)
, MB group such as AM, IVb group such as Sn, Pb, Vb group such as P (phosphorus), As, Sb, Bi, ■b group such as Se, Te, etc.
One or more of various elements such as each element of the group may be contained in an appropriate combination as a catalyst component such as a catalyst metal component.

Among these, those containing at least palladium, antimony and vanadium are particularly preferred.

In preparing the catalyst, the antimony and vanadium can be combined with various compounds such as halides,
Antimony is usually supported by antimony trioxide, and vanadium is usually supported by metavanadate. Ammonium is particularly preferably used.

The carrier used in the supported palladium-based catalyst may be any carrier as long as it can be used as a carrier for a catalyst that can be used in the reaction, and specific examples include silica, alkali, and silica alkali. Kusu, Titania,
Typical examples include oxide carriers such as zirconia, magnesia, and zeolite, and activated carbon. Among these, silica, titania, etc. are particularly preferred.

Note that these carriers may be used alone or in combination of two or more as a mixture.

The alkali metal carboxylates used as catalyst activity promoting components include carboxylates (aliphatic carboxylates, aromatic carboxylates, alicyclic carboxylates) of alkali metals (lithium, sodium, potassium, rubidium, or cesium). There is no particular restriction as long as it is a carboxylate (formula carboxylate, etc.), but
Usually, acetates of the various alkali metals mentioned above, such as cesium acetate, are preferably used.

Incidentally, these may be used alone, or two or more kinds or a combination thereof may be used.

As the alkali metal halides optionally used as catalyst activity promoting components, mention may be made of fluorides, chlorides, bromides or iodides of lithium, sodium, potassium, rubidium or cesium. Among these, chlorides of the various alkali metals mentioned above, such as cesium chloride, are usually preferably used.

Note that these may be used alone, or
Two or more types may be used in combination.

It is preferable that the alkali metal carboxylate is supported in an amount of 0.01 to 40 mmol per gram of the carrier, but the amount is not limited to this range.

5 The alkali metal halide does not necessarily need to be supported, but it is usually preferable to support it together with the alkali metal carboxylate. In that case, the amount of alkali metal halide is 0.01 to 40 m per 1 g of carrier.
It is preferable to carry the amount within the range of the mo statement, but
It is not limited to this range.

In the method of the present invention, the catalyst whose activity has been reduced or deactivated is subjected to a series of special treatment steps as described above, namely, a heat treatment step in which oxidation treatment and reduction treatment are alternately performed;
It can be regenerated by a subsequent chlorination treatment step.

(Heat treatment step) Oxidation treatment> The oxidation treatment involves using a gas containing molecular oxygen,
This is carried out by subjecting the target catalyst to oxidation treatment at a temperature range of 100 to 600°C. If this oxidation treatment temperature is too low, the incineration and removal of deposits on the catalyst (such as carbon 6 elements) will be insufficient; on the other hand, if it is too high, sintering of catalyst metal components such as palladium will occur. Unable to perform sufficient regeneration. A particularly preferable temperature range for the oxidation treatment is about 200 to 400°C.

As the molecular oxygen-containing gas used in this oxidation treatment, pure oxygen can be used, or normally, it is preferable to use one diluted with air or an inert gas such as nitrogen or water vapor. In this case, the oxygen concentration is 0.1 to 5
It is preferable to adjust it within the range of 0% by volume.

In addition, as described later, by carrying out this oxidation treatment by entraining carbon dioxide to the above molecular oxygen-containing gas,
The regeneration effect can be further improved.

<Reduction treatment> In the reduction treatment, the target catalyst is heated at 100 to 500°C, preferably 150 to 500°C, in an atmosphere of reducing gas.
1. More preferably, reduction treatment is carried out at a temperature range of 200 to 400°C.

As this reducing gas, various gases such as hydrogen, alcohol, and olefin can be used singly or in combination of two or more kinds, but hydrogen is particularly preferred.

Note that the reducing gas may be used after being diluted with an inert gas such as nitrogen or water vapor.

Furthermore, as will be described later, the regeneration effect can be further improved by carrying out this reduction treatment while entraining carbon dioxide to the above-mentioned reducing gas.

<Order of oxidation treatment and reduction treatment> In the catalyst regeneration method of the present invention, in the heat treatment step, the oxidation treatment and the reduction treatment are performed alternately. At this time, either the oxidation treatment or the reduction treatment may be performed first, or it is preferable that the last treatment among these alternating treatments be the reduction treatment.

There is no particular limit to the number of repetitions of the treatment, but one cycle is usually one cycle of oxidation treatment and reduction treatment.
It takes about 1 to 2 cycles.

Specifically, for example, there may be mentioned a method in which the process is carried out in the order of reduction treatment→oxidation treatment→reduction treatment, a method in which the order is carried out in oxidation treatment→reduction treatment→oxidation treatment→reduction treatment, and the like. A particularly preferred method is a method in which the heat treatment is performed in the order of reduction treatment→oxidation treatment→reduction treatment, and according to this method, for reasons that are not clear, it is possible to regenerate extremely effectively and efficiently.

Note that, before and after each treatment, desired treatments such as purging the system with an inert gas or the like may be performed as necessary.

<Entrained gas> In the oxidation treatment and reduction treatment in this heat treatment step, it is preferable to further include carbon dioxide in each of the gases (molecular oxygen-containing gas, reducing gas), especially in the heat treatment. Preferably, carbon dioxide is included during the entire process.

By allowing carbon dioxide to be present (entrained) in these heat treatments, even more effective regeneration can be achieved. The concentration of this entrained carbon dioxide is not particularly limited, and is usually
It is preferable to set it in the range of 10 to 99% by volume.

The effect of carbon dioxide is not clear, but it is presumed to be related to, for example, the effect of promoting the thermal stability of the alkali metal carboxylate, which is one of the activity-promoting ingredients.

(Halogenation treatment step) By performing the heat treatment step, the carbonaceous matter adhering to the catalyst whose activity has decreased or has been deactivated can be incinerated and removed, and palladium and other metal components can be returned to a reduced state or an appropriate oxidation state. I'll come.

Although this may restore the catalytic activity,
If this heat treatment step alone is used, the restoration of catalyst activity may be insufficient depending on the case, or even if it is restored, the catalyst may lack stability and its activity may decrease in a short period of time, or due to repeated reaction and regeneration. Problems such as the restoration rate gradually becoming insufficient occur, making it impossible to achieve the object of the present invention.

In the catalyst regeneration method of the present invention, the catalyst (i.e., regenerated intermediate catalyst) that has been subjected to a predetermined treatment in the heat treatment step is heated at 100 to 300°C in a gas stream containing a carboxylic acid and a halogen-containing compound. Preferably 150-25
Process at a temperature range of 0-'C.

The halogen-containing compound used in this halogenation treatment step is not particularly limited, but any compound that essentially contains a halogen and decomposes in whole or in part to supply halogen to the catalyst can be used. good.

However, considering the convenience of use, in the present invention, hydrogen fluoride, hydrogen chloride,
Hydrogen halides such as hydrogen bromide and hydrogen iodide; fluoromethane, chloromethane, methylene chloride, chloroform,
Halogenated methane derivatives such as carbon tetrachloride, methane bromide, and methane iodide; carbonyls such as carbonyl fluoride, phosgene, and carbonyl bromide; fluoroacetic acid, chloroacetic acid, acetic bromo, dichloroacetic acid, trichloroacetic acid, and chloropropion acids, halogenated carboxylic acids such as chloroacetic acid, and their esters: chloroacetaldehyde,
Halogenated aldehydes such as dichloroacetaldehyde, halogenated ketones such as chloroacetone, fluorinated ethane, chloroethane, bromated ethane, 1,2-dichloroethane, 1.1-dichloroethane, 1,1.1-trichloroethane, 1. 2-dichloropropane, chlorobutane,
Examples include halogenated hydrocarbons such as 1,4-dichlorobutane, chlorolaten, and 1,4-dichlorobutene.

Among these, chlorohydrocarbons such as 1,4-dichlorobutene and chloroacetic acids such as monochloroacetic acid are preferred, and 1,4-dichlorobutane is particularly preferred.

Note that these halogen-containing compounds may be used alone or in combination of two or more.

The carboxylic acids used in this halogenation treatment may include various types such as aliphatic carboxylic acids, aromatic carboxylic acids, alicyclic carboxylic acids, etc., or lower carboxylic acids such as acetic acid and propionic acid. Carboxylic acids are preferred, particularly acetic acid.

In this halogenation treatment, there is no particular restriction on the respective concentrations in the mixed gas containing the carboxylic acid and the halogen-containing compound, but usually the concentration of the carboxylic acid is in the range of 5 to 85% by volume, and the halogen-containing compound is It is preferable that the concentration of the contained compound is in the range of 0.001 to 5% by volume.

Note that this mixed gas can be used by appropriately containing an appropriate inert gas such as nitrogen or water vapor as a diluent, and if necessary, additives other than those mentioned above can be added as appropriate. It can also be included.

<Addition of activity-promoting component> In the catalyst regeneration method of the present invention, at least the heat treatment step and the halogenation treatment step may be carried out in this order, and if necessary, any other addition may be added. Operations and processing may be combined.

3 For example, as desired, at any point related to this regeneration, that is, a stage before the start of the heat treatment step (including the time of reaction), a stage from the start of the heat treatment step to the end of the halogenation treatment step. and at an appropriate point in the stage after the completion of the halogenation treatment process (including the time of reaction),
The catalyst may be supplemented with a catalyst component of an alkali metal carboxylate salt which is an activity promoting component. Among these, it is preferable to replenish the activity promoting component to the catalyst at a stage from the start of the heat treatment step to the end of the halogenation treatment step.

To replenish the catalyst with this activity-promoting component, the activity-promoting component is entrained in a processing gas such as a regenerated processing gas (which may be a purge gas or a reaction gas), and then added onto the catalyst. A method of supporting the catalyst, or a method of adding and supporting the catalyst on the catalyst by first taking out the catalyst from the regenerator, adding thereto an activity promoting component dissolved in a solvent consisting of water and/or alcohol, and evaporating the solvent. This can be suitably carried out by, for example, Specifically, for example, a method may be mentioned in which the heat treatment process is carried out by entraining the vapor of the activity-promoting component such as the alkali metal carboxylate into the heat treatment gas.

Incidentally, such replenishment of the activity-promoting component is not necessarily essential, but it is necessary to further improve the stability of the catalyst after the regeneration treatment, and from this point of view, it is preferable to carry out the replenishment as appropriate.

- The catalyst that has been regenerated as described above can be used as it is for the reaction (the reaction to produce an unsaturated diester from a reaction gas containing a conjugated diene, a carboxylic acid, and molecular oxygen by a gas phase flow reaction). can.

This gas phase flow reaction can be carried out by any desired method such as a fixed bed method or a fluidized bed method.

Various kinds of conjugated dienes can be used as the conjugated diene, but usually conjugated dienes having 6 or less carbon atoms, such as tutadiene, isoprene, piperylene, 2,3-dimethyltutadiene, cyclopentadiene, etc., are preferably used. used,
Among these, butadiene, isoprene, etc. are preferred, and butadiene is particularly preferred.

In addition, these may be used individually by 1 type, and may use 2 or more types together.

Further, as the carboxylic acid to be reacted with the conjugated diene, any carboxylic acid commonly used in this field can be used. Specifically, for example, acetic acid,
Examples include aliphatic carboxylic acids such as propionic acid, butyric acid, isoacetic acid, pentanoic acid, and hexanoic acid, alicyclic carboxylic acids such as cyclohexanecarboxylic acid, and aromatic carboxylic acids such as benzoic acid. Among these, acetic acid is particularly preferred.

In addition, these may be used individually by 1 type, and may use 2 or more types together.

The oxygen used in the reaction may be supplied to the reaction system as pure oxygen or as a mixed gas such as air.

the conjugated diene in the reaction gas subjected to the reaction;
The respective concentrations of carboxylic acid and oxygen are not particularly limited, and the respective concentrations can be varied over a wide range, for example, in the range of 1 to 98% by volume. Preferably, the concentration of conjugated diene in the reactant gas to be supplied is appropriately selected in the range of 1 to 85% by volume, the concentration of carboxylic acid in the range of 5 to 85% by volume, and the concentration of molecular oxygen is adjusted so that the reactant gas is in the explosive range. It may be appropriately selected within a range that does not result in the composition. in this case,
The concentration of molecular oxygen is usually preferably selected from a range of 1 to 50% by volume.

The reaction can also be carried out in the presence of other components such as an inert gas that does not interfere with the reaction, such as nitrogen, argon, and carbon dioxide.

In addition, if desired, the reaction gas may contain added acids (for example, chlorohydrocarbons such as 1,4-dichlorobutene, monochloroacetic acid, etc.) to improve catalyst activity or selectivity or extend catalyst life. halogen-containing organic compounds such as chlorine derivatives of carboxylic acids, etc.) may be contained as appropriate.

7. The feed rate of the reaction gas when performing the above reaction may be appropriately selected depending on other conditions such as the catalyst composition, the composition of the reactants, and the reaction conditions, the target yield of the product, etc. Usually 100 to 10,0 per unit catalyst
009. /hr, preferably 500
Selected from the range of ~5,000 sentences/hr.

The reaction temperature is not particularly limited, and is usually 1
It is appropriate to set the temperature within the range of 00 to 300C, preferably 100 to 2500C.

The reaction pressure is not particularly limited as long as the reaction gas and the produced gas remain in a substantially gaseous state.
The reaction may be carried out under reduced pressure, normal pressure or increased pressure. Generally, it is carried out under normal pressure or pressurized conditions.

As described above, unsaturated diesters (carboxylic acid diesters of unsaturated glycols), especially tutadiene, can be produced by the oxidative acyloxylation reaction of conjugated dienes with carboxylic acids, particularly industrially, by the oxidative acetoxylation reaction of tutadiene with acetic acid. It is possible to produce diacetoxybutene whose main component is 1,48 diacetoxybutene in a high yield and stably for a long period of time.

The catalyst whose activity has been reduced or deactivated by this reaction can be suitably regenerated according to the catalyst regeneration method of the present invention, and can be effectively used as a catalyst for producing the unsaturated diester.

[Examples] Next, the present invention will be explained in more detail by examples and comparative examples, but the present invention is not limited to the following examples and does not depart from the scope of the gist of the present invention. as long as
Various modifications are possible.

(Example 1) (A) Antimony trichloride (128.7 g) was dissolved in 1,460 mM acetone to make a homogeneous solution.
750 g of 200 gm silica support (2,000 m
1) was placed in a flask, and the solution was added thereto to impregnate the carrier. The pressure inside the flask was reduced using an aspirator to evaporate acetone, and antimony trichloride was supported on the carrier.

This supported material was poured into 3,000 ml of a neutralizing solution consisting of an aqueous ammonium carbonate solution with a concentration of 20% by weight.
After carrying out a neutralization reaction over a period of minutes, washing with pure water 10 times, drying at 110° C. overnight, and firing treatment at 500° C. for 3 hours under atmospheric pressure in a stream of air.

Put this baked product into a rotary evaporator and
2.2 g of tetraammine palladium nitrate, 44.
An aqueous solution (1450 ml) in which 0 g of ammonium metavanadate was dissolved was added, and the water was evaporated to support the catalyst metal component.

Thereafter, this supported material was dried at 906C overnight, and then calcined at 500'C for 3 hours in an air stream, and then the regenerated intermediate catalyst was heated for 2 hours under a hydrogen stream.
Reduction treatment was performed at 00° C. for 2 hours, followed by 400°C for 2 hours.

Next, an aqueous solution in which 120 g of cesium chloride and 120 g of cesium acetate were dissolved in 1,420 mM water was added to this reduced product, and the water was evaporated. ) was obtained. Hereinafter, this catalyst may be referred to as catalyst I.

(B) - 1,500 ml of the catalyst prepared in step (A) above was charged into a stainless steel fluidized bed reactor with an inner diameter of 81 mm, and 1,500 ml of the catalyst prepared in step (A) above was charged into the reactor.
A mixed gas of 30:3:57 (volume ratio) was introduced at a rate of 1.5001/hour, and a continuous reaction (fluidized bed gas phase flow reaction) was carried out at 185°C.

After a suitable time after starting the reaction, the catalyst l! Table 1 shows the production amount and selectivity of diacetoxybutenes (1,4-cyacetoxyphthene-2 and its isomer mixture) per liter.

Table 1: In this reaction, after collecting data at the 800th hour, the supply of the mixed gas as a reaction raw material was stopped.

Then, nitrogen gas is passed instead, and this state is maintained for one hour, and then the temperature is slowly lowered to room temperature. After that, the reactor is opened, the catalyst is taken out, and it is deactivated (reduced activity). Hereinafter, this deactivated catalyst may be referred to as deactivated catalyst I.

(C) The deactivated catalyst obtained in (B) above, 333 mJ1, was heated with an inner diameter of 5
The mixture was charged into a 5 mm stainless steel fluidized bed regenerator and heated to 150°C while introducing nitrogen gas at a rate of 300 g/hr. After that, a mixed gas of carbon dioxide and hydrogen at a ratio of 65:35 (volume ratio) was added. while introducing it at a rate of 500 sentences per hour.
The deactivated catalyst was reduced at 300° C. for 7 hours.

Next, after expelling the reduction gas with nitrogen gas, a mixed gas of carbon dioxide:oxygen:nitrogen of 76:5:19 (volume ratio) was introduced at a rate of 500 m2/hour, and heated at 300°C for 7 hours. The deactivated catalyst was oxidized over time.

Thereafter, after expelling the oxidizing gas with nitrogen gas, a mixed gas of carbon dioxide:hydrogen in a ratio of 65:35 (volume ratio) was introduced at a rate of 500 m/hr for 30 min.
The deactivated catalyst was reduced at 0° C. for 7 hours.

Example of halogenation treatment step> Next, the catalyst that has undergone the heat treatment step is cooled to 185° C. in a nitrogen gas stream, and then acetic acid = 1,4-
Dichlorophthene: Nitrogen 36.7: 0. Mouth 05:
The chlorination treatment was carried out for 12 hours while introducing a mixed gas of 63.35 (volume ratio) at a rate of 474 tons per hour to obtain a regenerated catalyst. Hereinafter, the catalyst that has been regenerated for the first time may be referred to as a regenerated catalyst.

In addition, during the regeneration treatment by the heat treatment step and the halogenation treatment step, each of the components used in each of the treatment steps (oxidation treatment, reduction treatment, and halogenation treatment step) is added for the purpose of adding an activity promoting component to the catalyst. The regeneration treatment mixed gas (oxidation treatment gas, reduction treatment gas, and halogenation treatment gas) was accompanied by cesium acetate in the following manner.
A container filled with 1,000 mfL of a silica carrier (spherical shape with a diameter of 3 mm) supporting 00 g of cesium acetate was heated to the respective regeneration treatment temperatures, and the respective regeneration treatment mixed gases were passed therethrough to remove cesium acetate. This was done by incorporating steam and introducing it into the fluidized bed regenerator.

(D) - After the regeneration treatment in (C) above, the oxidative acyloxylation reaction of tutadiene is subsequently carried out using the fluidized bed regenerator as a reactor while the regenerated catalyst is still in the fluidized bed regenerator. It was carried out in the same manner as in (B).

However, this reaction was carried out by introducing a mixed gas (reaction raw material) having the same composition as shown in (B) above at a rate of 500 m/hr.

The results are shown in Table 2.

5 (E) and ・The catalyst that was regenerated for the first time, that is, the reaction of (D) performed using the regenerated catalyst, causes deterioration again (reduction in activity).
The deactivated catalyst (deactivated catalyst ■) was regenerated again in the same manner as in (C) above to obtain a regenerated catalyst ■.

Using this regenerated catalyst (2), the reaction was carried out in the same manner as in (D) above.

The results are shown in Table 2.

(Example 2) 333 mJl of the deactivated catalyst obtained in (B) of Example 1 was
Regeneration treatment was carried out in the same manner as in Example 1 (C) except that nitrogen was used instead of carbon dioxide in the heat treatment step (
1st playback).

Thereafter, the oxidative acyloxylation reaction of tutadiene was carried out in the same manner as in Example 1 (D) using the regenerated catalyst obtained through the first regeneration treatment.

The results are shown in Table 2.

As a result of this reaction, the catalyst 6 which has deteriorated again (reduced activity) is regenerated in the same manner as the first regeneration treatment described above.

Thereafter, using the regenerated catalyst obtained in this second regeneration treatment, oxidative acyloxylation reaction of phtadiene was carried out in the same manner as in Example 1 (D).

The results are shown in Table 2.

(Comparative Example 1) The same procedure as (C) of Example 1 except that the treatment with acetic acid and 1,4-dichlorobutene (chlorination treatment step) was removed from the deactivated catalyst shown in Example 1, 333 mJ1. Regeneration processing was performed in the same manner. Thereafter, using this regenerated catalyst, oxidative acyloxylation reaction of phtadiene was carried out in the same manner as in Example 1 (D).

The results are shown in Table 2.

(Example 3) The deactivated catalyst I shown in Example 1, 333m, was treated with 1,4-dichlorobutene (volume ratio Q, 0
05) instead of monochloro acid m (volume ratio o, ooa
) The regeneration process was carried out in the same manner as in (C) of Example 1, except that the process was performed using (first regeneration).

Thereafter, using this regenerated catalyst, the (
Oxidative acyloxylation reaction of butadiene was carried out in the same manner as in D).

The results are shown in Table 2.

The catalyst, which had deteriorated (reduced activity) again in this reaction, was regenerated in the same manner as the first regeneration treatment described above (second regeneration).

Thereafter, using the regenerated catalyst obtained in this second regeneration treatment, the oxidative acyloxylation reaction of butadiene was carried out in the same manner as in Example 1 (D).

The results are shown in Table 2.

(Example 4) The catalyst whose activity decreased due to the reaction in Comparative Example 1 was regenerated in the same manner as in Example 1 (C).

Using this regenerated catalyst, the oxidative acyloxylation reaction of butadiene was carried out in the same manner as in Example 1 (D).

The results are shown in Table 2.

(Example 5) 333 ml of the deactivated catalyst ■ obtained in (B) of Example 1 was subjected to the heat treatment step and the halogenation treatment step, except that cesium acetate vapor was not entrained in these treatment gases. The regeneration process was performed in the same manner as in Example 1 (C). Thereafter, using this regenerated catalyst, Example 1
The oxidative acyloxylation reaction of tutadiene was carried out in the same manner as in (D).

The results are shown in Table 2.

9 [Effects of the Invention] According to the present invention, there is provided a supported palladium-based catalyst containing an alkali metal carboxylate or an alkali metal halide as an activity promoting component, and a conjugated diene, a carboxylic acid, and molecular oxygen. The catalyst used when producing unsaturated diesters (unsaturated glycol diesters) by conducting a gas phase flow reaction with a reaction gas containing
As a method of regenerating when activity decreases or deactivates,
We regenerate degraded catalysts using a specific method that sequentially processes them according to a series of special treatment steps.
The performance of the catalyst, such as its activity, selectivity and stability, can be very effectively and efficiently restored to the high levels of the original catalyst before deterioration. In addition, this regeneration prevents the activity-promoting components, such as alkali metal carboxylates and alkali metal halides, from being degraded or washed away, resulting in excellent performance such as catalytic activity, selectivity, and stability. Since it can be restored sufficiently, the reaction can be restarted immediately after the regeneration treatment, and furthermore, the usage period of the catalyst can be greatly improved by repeating the reaction and regeneration. Furthermore, this regeneration method has the advantage that the regeneration operation itself is extremely simple.

As described above, the catalyst regeneration method of the present invention has various advantages and has extremely high industrial utility value. As described above, according to the present invention, it is possible to provide an industrially extremely advantageous method for regenerating a supported palladium-based catalyst for producing an unsaturated diester by a gas-phase flow oxidative acyloxylation reaction of a conjugated diene with a carboxylic acid. can.

Claims (4)

[Claims] (1) A catalyst used in a method for producing an unsaturated diester by reacting a mixed gas containing a conjugated diene, a carboxylic acid, and molecular oxygen by a gas phase flow method, in which the alkali metal carbon dioxide is used as an activity promoting component. When regenerating a supported palladium-based catalyst in which an acid salt or an alkali metal halide is supported, the catalyst whose activity has decreased is heated at a temperature in the range of 100 to 600°C using a gas containing molecular oxygen. A heat treatment step in which an oxidation treatment and a reduction treatment are performed at a temperature in the range of 100 to 600° C. in a reducing gas atmosphere are alternately carried out, and the catalyst obtained by the heat treatment step is treated with a carboxylic acid. 1. A method for regenerating a catalyst for producing an unsaturated diester, comprising a halogenation treatment step in a gas stream containing a halogen-containing compound at a temperature in the range of 100 to 300°C. (2) The method for regenerating a catalyst for producing an unsaturated diester according to claim 1, wherein the catalyst contains palladium, antimony, and vanadium. (3) The method for regenerating a catalyst for producing an unsaturated diester according to claim 1 or 2, wherein the heat treatment step is performed in the order of the reduction treatment, oxidation treatment, and reduction treatment. (4) The method for regenerating a catalyst for producing an unsaturated diester according to any one of claims 1 to 3, wherein the heat treatment step is performed in the presence of a gas containing carbon dioxide.