JPH09124535A - Production of acetaldehyde - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing acetaldehyde in high yield and with a long life of the catalyst in a reaction that oxidizes ethylene. SOLUTION: This method producing acetaldehyde is designed to catalytically oxidize ethylene while circulating an aqueous solution of a catalyst that contains at least one compound selected from palladium compounds, heteropoly-acids and their salts in such a way that the circulating liquid quantity for the water- soluble catalyst is set so that LHSVo is 10 hr<-1> or more and that the conversion ratio of vanadium [V] in the heteropoly-acid is 60% or less to maintain the turnover frequency of the palladium catalyst [total molar number of ethylene consumed by the reaction/molar number of palladium)]/sec at 5 or less.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing acetaldehyde by oxidizing ethylene.

[0002]

Conventionally, acetaldehyde has been industrially
Manufactured by Wacker oxidation of ethylene with oxygen,
Two methods, a one-step method and a two-step method, have been put to practical use using a water-soluble catalyst system of palladium chloride, copper chloride and hydrochloric acid. In the two-stage method, the oxidation of ethylene with palladium chloride and the reoxidation of cuprous chloride with air are separately performed, and the product acetaldehyde is separated and recovered from the aqueous solution on the way. The reoxidized water-soluble catalyst liquid is recycled and reused in the ethylene oxidation stage.

In the one-step method, ethylene and oxygen are simultaneously reacted with a water-soluble catalyst, and acetaldehyde is continuously separated and recovered therefrom. Palladium acts as a catalyst in the ethylene oxidation of palladium chloride by oxidizing ethylene and then reducing cupric chloride.
However, the Wacker method requires a high chloride ion concentration and a large amount of copper chloride in order to function effectively, has a strong corrosive property in the manufacturing equipment, and is a practically expensive corrosion resistant substance such as titanium. It is necessary to use materials such as Further, since a considerable amount of chlorinated by-products are generated in this manufacturing method, it is necessary to appropriately separate and dispose of them, so that the operating cost of the manufacturing method increases and improvement is required.

A system for carrying out the oxidation of olefins using a heteropolyacid in combination with palladium instead of cupric chloride is Eastman Kodak Co. (US 3485877), Matveev.
(JP-A-51-117189) and Catalytica Inc.
06852, Japanese Patent Publication No. 5-506181, Japanese Patent Publication No. 5-506853, Japanese Patent Publication No. 5-507024, and Japanese Patent Publication No. 63-500923). In the reactions described in the examples of these patents, the oxidation reaction of ethylene and the reoxidation reaction with oxygen are separately carried out in a batch reaction, and very good results are obtained.
However, according to the above examples, it has been found that the activity does not increase when the reaction is continuously carried out for a long time due to a problem such as palladium precipitation. In carrying out the reaction using these catalysts, what is particularly important industrially is that the activity of the catalyst is high, its change with time is as small as possible, and the selectivity of acetaldehyde is good. But,
None of the conventionally proposed reaction methods using these catalysts is necessarily sufficient for carrying out production of acetaldehyde on an industrial scale.

[0005]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a method capable of industrially producing acetaldehyde by oxidizing ethylene.

[0006]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present inventors have conducted earnest research on a reaction method in order to enhance the performance of a catalyst used in the production of acetaldehyde by oxidizing ethylene. The present invention has been completed by discovering the following reaction method, which has an extremely high yield, a very high selectivity of acetaldehyde, and a long life as compared with the conventional method. That is, the present invention provides at least one selected from a palladium compound, a heteropoly acid and salts thereof.
In the method for producing acetaldehyde by catalytic oxidation with ethylene while circulating an aqueous solution of a catalyst containing various compounds, the circulating liquid amount of the water-soluble catalyst is LHSV _0.
Is 10H ^-1 or higher and vanadium [V] in heteropolyacid
The reaction rate of the palladium catalyst should be 60% or less, and the turnover frequency of the palladium catalyst [(total number of moles of reacted ethylene) / (number of moles of palladium)] / sec should be 5 or less. It is a characteristic method for producing acetaldehyde.

The present invention will be described in detail below.
The palladium raw material contained in the catalyst used in the present invention is not particularly limited, but is usually a halide such as palladium chloride, an organic acid salt such as palladium acetate,
Palladium nitrate, palladium sulfate, sodium tetrachloropalladate, etc. are used.

The heteropolyacid is phosphorus and silicon as the heteroatoms, and the heteroatom containing at least one element selected from the group consisting of molybdenum, tungsten and vanadium as the polyatoms. . Specifically, it is molybdovanadolinic acid or tungstovanadolinic acid, and the salt thereof is at least one element selected from the group consisting of Group 1 elements, Group 2 elements and Group 3 elements of the periodic table. Are exemplified. In particular, a heteropoly acid whose hetero atom is phosphorus or silicon and whose poly atom is at least one element selected from the group consisting of tungsten, molybdenum and vanadium is practically advantageous.

Further, the salt of a heteropoly acid is a metal salt obtained by substituting a part of hydrogen atoms of an acid produced by condensing two or more kinds of inorganic oxygen acids. The metal in which the hydrogen atom of the heteropolyacid is replaced is at least one selected from the group consisting of groups 1, 2 and 3 in the periodic table according to the International Union of Pure and Applied Chemistry, Revised Edition of Inorganic Chemistry Nomenclature (1989). It is a seed element. Among these salts of heteropolyacid, metal salts of lithium, sodium, potassium, magnesium and cerium are particularly preferable. Further, as salts of heteropolyacids which are preferable in terms of catalytic performance and practical use, lithium salt of molybdovanadric acid, sodium salt of molybdovanadric acid and sodium salt of tungstovanadric acid can be mentioned.

The catalyst used in the present invention is a catalyst containing a palladium compound and at least one compound selected from heteropolyacids and salts thereof, and the concentration thereof is not limited, but the concentration of palladium in the catalyst is , Usually 0.00
Used at 5-2000 mmol / L, especially 0.05-500 mmol / L
At L, more favorable results are given. The reaction proceeds sufficiently even when the palladium content is 2000 mmol / L or more, but excess palladium is not economical because palladium is expensive, and Pd is often precipitated during the reaction, which is practically disadvantageous. On the other hand, if the Pd concentration is too low, the carbonyl compound formation activity is low, which is not practical.

The concentration of the heteropolyacid and salts thereof is preferably 0.01 to 0.6 mol / L, particularly 0.1 to 0.5 mol.
In / L, a more favorable result is given. Its concentration is
If it is less than 0.01 mol / L, the proportion of reduced heteropolyacid increases, leading to a decrease in activity and life. On the other hand, if it is higher than 0.6 mol / L, the viscosity and specific gravity of the catalyst solution become very large, which is not preferable in practice. The method for preparing the catalyst used in the present invention is not particularly limited as long as it has the above-mentioned catalyst composition, and a conventional method is used.

That is, usually, it is prepared by mixing a water-soluble halide such as palladium chloride, an organic acid salt such as palladium acetate, palladium nitrate, palladium sulfate, sodium tetrachloropalladate and the like with a heteropolyacid and a salt thereof. In particular, it is not limited to this preparation method. The salt of a heteropoly acid is usually obtained by adding an aqueous solution of the above-mentioned metal halogen salt, carbonate, nitrate, acetate, sulfate or the like to an aqueous solution of the heteropoly acid.

In the method of the present invention, when ethylene is oxidized to produce acetaldehyde, the reaction temperature is 50 to 50.
The temperature is 200 ° C, but preferably 90 to 150 ° C is practically advantageous. When the two-step method is used, the temperatures of the ethylene oxidation reaction and the catalyst reoxidation reaction can be set independently. Further, it is practically advantageous that the reaction pressure is 0 to 50 kg / cm ² G from the viewpoint of equipment, but when the two-stage method is adopted as the reaction system, it is more preferably 1 to 1 in the ethylene oxidation reaction system. It is in the range of 30 Kg / cm ² G. In the method of the present invention, the above-mentioned one-step method and two-step method can be adopted as the reaction method, but it is practically advantageous to adopt the two-step method.

That is, in the two-step method, the oxidation of ethylene by the palladium salt and the reoxidation of the heteropolyacid by oxygen are carried out separately, and the acetaldehyde product is removed and recovered from the aqueous solution on the way. The reoxidized water-soluble catalyst liquid is recycled and reused in the ethylene oxidation stage.

In the method of the present invention, the circulating liquid amount of the catalyst liquid varies depending on the size and shape of the reaction apparatus, the contact / diffusion state of the gas and the liquid in the reaction tube, and the optimum flow amount is different. Is more preferable. However, since the increase of the circulating liquid amount increases the load of the circulating liquid feeding pump and the operating cost thereof, the liquid hourly space velocity (LHSV ₀ ) 100 is preferable.
It is preferably used at ⁰ Hr ^-1 or less, particularly 500 Hr ^-1 or less. On the other hand, when the amount of circulating liquid is small, the amount of reduced heteropolyacid generated by the oxidation reaction of ethylene increases, so the precipitation of Pd increases and the deactivation of the activity is accelerated, so that LHSV _{0 of at} least 10 Hr ^-1 or more is obtained. is necessary.

The conversion rate of vanadium in the heteropoly acid reduced in the catalyst solution by the ethylene oxidation reaction is 60.
It is desirable to keep the percentage below. When the conversion rate of vanadium in the reduced heteropolyacid greatly exceeds 60%, the precipitation of palladium increases with the reaction, which leads to a decrease in the activity during the reaction for a long time.

Further, the turnover frequency of palladium changes depending on the conditions of the amount of circulating liquid and the concentration of palladium.
If at least one of the circulating liquid amount and the palladium concentration is small, the turnover frequency of palladium becomes small. In the method of the present invention, the turnover frequency of palladium is preferably 5 or less in order to maintain the ethylene conversion rate and the catalyst life long. If the circulating fluid volume is very small, the amount of reduced heteropoly acid will increase,
It becomes impractical due to the reduction of catalytic activity and life due to palladium deposition and the like. On the other hand, when the palladium content is extremely low, the ethylene conversion rate is lowered, so it is necessary to increase the circulating liquid amount and increase the activity.

The gas supplied to the reaction system in the method of the present invention comprises ethylene and oxygen, and if necessary nitrogen, carbon dioxide or a rare gas may be used as a diluent. In the present invention, particularly when the reaction is carried out in a two-step method, in the oxidation reaction of the heteropolyacid catalyst solution, the heteropolyacid reduced by the ethylene oxidation reaction is reoxidized to such an extent that the ethylene oxidation reaction is not hindered. If so, it is sufficient to supply a sufficient reoxidation reaction temperature and oxygen amount for that purpose. In carrying out the method of the present invention,
It is advantageous to use a high-purity ethylene as the raw material ethylene, but a slight amount of a lower saturated hydrocarbon such as methane, ethane or propane may be mixed in. Oxygen can also be supplied in the form of air diluted with an inert gas such as nitrogen or carbon dioxide, for example, air. The reaction mixture gas has a space velocity (GHSV) of 100 to 10000 Hr ^-1 , particularly 500 to 50 under standard conditions.
It is preferred to pass through the catalyst at 00Hr ^-1 .

[0019]

The present invention will be described in more detail with reference to the following examples. In the following examples, the method of oxidation reaction of ethylene to acetaldehyde included in the present invention is shown. The ethylene oxidation reaction in the present invention has an internal volume of 1.6 cc and
It was carried out using a stainless steel pipe reactor with 6.6 cc. Glass beads were filled in the pipe reactor with an internal volume of 6.6 cc in order to efficiently contact the reaction raw material gas with the catalyst liquid.

Regarding the exemplified ethylene oxidation reaction, while circulating a predetermined amount of the above-mentioned catalyst liquid with a circulation pump,
Ethylene is supplied before the pipe reactor to react at a predetermined reaction temperature and reaction pressure, and the reaction mixture discharged from the pipe reactor is separated and separated from the catalyst liquid by a gas-liquid separator, acetaldehyde and unreacted ethylene. did. The product was quantified by gas chromatography. The palladium turnover frequency and TOF were expressed as [(total moles of reacted ethylene) / (moles of palladium)] / second. The conversion rate of vanadium [V] of the catalyst solution is (total number of moles of reacted ethylene) / (number of moles of vanadium [V] / 2) × 100.

Example 1 The catalyst is palladium acetate 0.5 mm
ol / L was dissolved in 0.3 mol / L Na ₃ H ₃ PMo ₉ V ₃ O ₄₀ and prepared. The reaction is carried out by a two-step method, and in the ethylene oxidation reaction system,
In the above pipe reactor with an internal volume of 1.6 cc, ethylene
Reaction temperature 120 while feeding at 0.6NL / H (GHSV 380H ^-1 ).
The reaction is carried out at a temperature of ℃ and a reaction pressure of 9 Kg / cm ² G.
While supplying 1.51NL / H (GHSV 957H ^-1 ), reaction temperature 120
The reaction was carried out at a reaction pressure of 5 Kg / cm ² G at 0 ° C., and the catalyst solution was continuously circulated at a rate of 0.3 L / H (LHSV 190H ⁻¹ ) by a circulation pump. The product and unreacted gas were separately collected and analyzed 5 hours and 100 hours after the ethylene was fed. As a result, the ethylene conversion rate after 5 hours was 95% and the ethylene conversion rate after 100 hours was 94%. At that time, the conversion rate of vanadium [V] was 19% and Pd TOF was 0.05s ^-1 .

(Example 2) In Example 1, both pipe reactors had an internal volume of 6.6 cc, the concentration of palladium acetate in the catalyst solution was 0.05 mmol / L, and the supply amounts of ethylene and oxygen were changed. 4NL / H (GHSV 235H ^-1 ) and 3.02NL / H (GHSV
178H ^-1 ), and the circulation rate is 0.6 L / H (LHSV ₀ 35H ^-1 ).
Same as Example 1 except that

(Example 3) In Example 1, Na ₃ H in the catalyst solution was used.
₃ using _{Li 3 H 3 PMo 9 V 3} O 40 , instead of the PMo ₉ V ₃ O _40, further, except that the amount of circulating fluid to the ^{0.4L / H (LHSV 253H -1)} , as in Example 1 I did the same.

Example 4 In Example 1, Na ₃ H in the catalyst solution was used.
Same as Example 1 except Na ₃ H ₃ PW ₉ V ₃ O ₄₀ was used instead of ₃ PMo ₉ V ₃ O ₄₀ .

Example 5 In Example 1, Na ₃ H in the catalyst solution was used.
₃ PMo ₉ V ₃ O ₄₀ except for using _{Ce 1 H 3 PMo 9 V 3} O 40 , instead of, were the same as in Example 1.

Example 6 In Example 1, Na ₃ H in the catalyst solution was used.
₃ PMo ₉ V ₃ O ₄₀ except for using _{Mg 1.5 H 3 PMo 9 V 3} O 40 , instead of, were the same as in Example 1.

Example 7 In Example 1, Na ₃ H in the catalyst solution was used.
Same as Example 1 except Na ₃ H ₄ PMo ₈ V ₄ O ₄₀ was used instead of ₃ PMo ₉ V ₃ O ₄₀ .

Comparative Example 1 The catalyst is palladium acetate 0.05 m
It was prepared by dissolving mol / L in 0.3 mol / L Na ₃ H ₃ PMo ₉ V ₃ O ₄₀ . The reaction is carried out by a two-step method, and in the ethylene oxidation reaction system,
In the pipe reactor with the above internal volume of 6.6cc, ethylene
Reaction temperature 120 while supplying with 4.0NL / H (GHSV 606H ^-1 ).
The reaction is carried out at a temperature of ℃ and a reaction pressure of 9 Kg / cm ² G.
While supplying 3.02NL / H (GHSV 458H ^-1 ), reaction temperature 120
The reaction was carried out at 0 ° C. and a reaction pressure of 5 kg / cm ² G, and the catalyst solution was continuously circulated at a rate of 0.3 L / H (LHSV 46H ⁻¹ ) by a circulation pump. The product and unreacted gas were separately collected and analyzed 5 hours and 100 hours after the ethylene was fed. as a result,
The ethylene conversion rate after 5 hours was 65%, and the ethylene conversion rate after 100 hours was 45%. The conversion of vanadium [V] after 5 hours was 86% and Pd TOF was 2.2s ^-1 .

Comparative Example 2 In Example 1, both pipe reactors had an internal volume of 6.6 cc, and the concentration of palladium acetate in the catalyst solution was 0.01 mmol / L. 4NL / H (GHSV 606H ^-1 ) and 3.02NL / H (GHSV
458H ^-1 ), and the circulation rate was 0.4 L / H (LHSV 61H ^-1 ). As a result, 5
The ethylene conversion rate after 50 hours was 50%, and the ethylene conversion rate after 100 hours was 32%. Also, vanadium [V] after 5 hours
The conversion rate was 50% and Pd TOF was 6.2s ^-1 .

(Comparative Example 3) In Example 1, the circulation rate was 0.05 L /
Same as Example 1 except that H (LHSV 8H ^-1 ) was used. As a result, the ethylene conversion rate after 5 hours was 35% and the ethylene conversion rate after 100 hours was 15%. The conversion of vanadium [V] after 5 hours was 42%, and Pd TOF was 0.1 s ^-1 .

Table 1 shows the results of the above Examples 1 to 7 and Comparative Examples 1 to 3.

[0032]

[Table 1]

[0033]

As described above, in the method of the present invention, in the reaction method of oxidizing ethylene to produce acetaldehyde, the yield and selectivity of acetaldehyde are extremely high and the life is long. It is an excellent method that can be obtained at a cost.

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[Procedure amendment]

[Submission date] December 12, 1995

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0022

[Correction method] Change

[Correction contents]

(Example 2) In Example 1, both pipe reactors had an internal volume of 6.6 cc, and the palladium acetate concentration in the catalyst solution was 0.05 mmol / L. 4NL / H (GHSV 606H ^-1 ) and 3.02NL / H (GHSV
912H ^-1 ), and the circulation rate is 0.6 L / H (LHSV ₀ 91H ^-1 ).
Same as Example 1 except that

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0030

[Correction method] Change

[Correction contents]

(Comparative Example 3) In Example 2, the circulation rate was 0.05 L /
Same as Example 2 except that H (LHSV 8H ^-1 ). As a result, the ethylene conversion rate after 5 hours was 25% and the ethylene conversion rate after 100 hours was 15%. The conversion of vanadium [V] after 5 hours was 50%, and Pd TOF was 0.5 s ^-1 .

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0032

[Correction method] Change

[Correction contents]

[0032]

[Table 1]

Claims (2)

[Claims] 1. A method for producing acetaldehyde by catalytic oxidation with ethylene while circulating an aqueous solution of a catalyst containing at least one compound selected from a palladium compound, a heteropoly acid and salts thereof, wherein the aqueous solution is used. The amount of the circulating liquid of the organic catalyst is ₁₀ H ^-1 or more at LHSV ₀ and the conversion rate of vanadium [V] in the heteropolyacid is 60% or less, and the turnover frequency of the palladium catalyst [(total moles of reacted ethylene is The method for producing acetaldehyde is characterized in that the reaction is carried out such that the number) / (the number of moles of palladium)] / second is 5 or less. 2. The heteropolyacid is molybdovanadolinic acid or tungstovanadolinic acid, and a salt thereof is at least selected from the group consisting of Group 1 element, Group 2 element and Group 3 element of the periodic table. The manufacturing method according to claim 1, wherein the manufacturing method is one kind of element.