JPS5934167B2 - Manufacturing method of vinyl acetate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for directly producing vinyl acetate J in high yield by reacting acetic anhydride with hydrogen while separating vinyl acetate and acetic acid.

More specifically, it is characterized by reacting acetic anhydride with hydrogen while separating vinyl acetate and acetic acid in the presence of palladium and/or its compound and an alkyl halide such as chloride, bromide and/or iodide. The present invention relates to a method for producing vinyl acetate. Conventionally, as a method for producing vinyl acetate, a method using acetylene as a raw material has been known for a long time, but in recent years, a method of converting the raw material to ethylene has been developed, and the method has changed to the more advantageous ethylene method. Direct synthesis of vinyl acetate from ethylene began with methods such as palladium chloride catalysts or the coexistence of sodium acetate in this system. On the other hand, this is a similar method in which acetaldehyde and acetic anhydride are used as raw materials to form ethylidene diacetate (1,1-diacetoxyethane).
Alternatively, a method of directly converting it into vinyl acetate and acetic acid has been proposed. [For example, Hydrocarbon P
Rocess, No. 1 (11) 287 (1965), UK Patent No. 1112555, US Patent No. 2021698, 242
5389, 2860159, etc. ] In other words, these methods include a direct reaction between acetaldehyde and acetic anhydride, and a method in which ethylidene diacetate is first produced by a reaction between acetaldehyde and acetic anhydride, and then this is thermally decomposed to produce vinyl acetate. Known (
・Ru. The present inventors continued their intensive research into a rational method for producing vinyl acetate using acetic anhydride as a raw material, and discovered a novel reaction in which vinyl acetate was synthesized in one step by reacting acetic anhydride with hydrogen. Completed a new method for producing vinyl acetate.

The present invention will be explained below.

Although the detailed reaction mechanism for producing vinyl acetate through the hydrogen reduction reaction of acetic anhydride according to the present invention is not clear, the overall reaction can be expressed by the following chemical reaction formula.

The reaction represented by the above chemical formula can be suitably carried out by using palladium and/or its compound and an alkyl halide such as chloride, bromide and/or iodide as a catalyst.

Metal catalysts are based on the use of palladium and/or its compounds, but can be used in any and all forms.

For example, the metal itself or in finely divided form;
Raney metal forms or carbonates, oxides, peroxides,
hydroxide, nitrate, sulfate, phosphate,... rogenide,
Cyanide, thiocyanide, sulfonate, C1~
C5 lower alkoxides such as methoxides or ethoxides, phenoxides, metal carboxylates in which the carboxy ion is derived from alkanoic acids having 1 to 20 carbon atoms;
There are oxylogenides, hydrides, carbonyls, nitrites, sulfites, phosphites, acetylacetone salts, sulfides, and compounds coordinated with ammonia, cyanide, amines, amino acids, etc. To give an example of some of them, P
d metal, PdX2, PdX2・2H20, PdX2・2
NH3, Pd(CN)2, Pd2HlPd(0H)2,
Pd(0H)2・2NH3, Pd(NO3)2, Pd2
O, PdO. PdO2, PdSO4・2H20,. Pd
2S, [Pd(PPh3)2]Cl2, PdS, . Pd
S2, Pd3(PO4)2, Na2PdX-Pd [(t(4H,)3P](CO)Cl2, K2PdX-Li2
PdX4, Pd(0Ac)2, Pd(AcAc)2, P
dX2(PhCN), Pd(SCN)2, Pd(NC
) 2, palladium benzenesulfonate (X in the above formula is F, .Cl, .Br or 1.Ph is a phenyl group, Ac
O represents an acetoxy group, and AcAc represents an acetylacetonate group.

) can be given. The metal catalyst can be used from the beginning or in a final state soluble in the reaction solution to form a homogeneous catalyst. Alternatively, insoluble or only partially soluble forms can be used, resulting in a heterogeneous catalyst system. In the case of heterogeneous catalyst systems, the metal compound or the metal itself,
It is also possible to use it in the form of a finely pulverized metal or Raney metal, but it can also be used in combination with a partner described below. In this case, the supporting method may be, for example, a conventional dipping method, kneading method, adsorption method, coprecipitation method, ion exchange method, etc., but other methods are also possible.

To give some examples, a carrier is impregnated with a solution containing a metal compound and other components as necessary, and then formalin, hydrogen, sodium formate, carbon monoxide, sodium borohydride, lithium aluminum hydride, or hydrazine is used. This method is carried out by modifying a metal compound into a metal using a conventional reduction method such as drying, but is not limited to these methods. As long as it is possible, it does not matter what method is used. Supports used include carbon, graphite, bone char, alumina, silica, silica alumina, barium sulfate, zeolite, spinel, alumina with magnenia, thoria, titanium oxide, zirconium oxide, thorium oxide, lanthanum oxide, cerium oxide, zinc oxide, Tantalium, clay, diatomaceous earth, celite, asbestos, pumice, bauxite, white earth, natural and treated white earths such as SuperFiltrOl, silicon carbide, zeolite and zeolite molecular sieves, ceramic honeycombs, poria, cement, etc. are used, but are preferred. is carbon, graphite, bone charcoal,
Alumina, silica, silica alumina, barium sulfate, zeolite, spinel, and alumina with magnesia are used. The above-mentioned carrier is used in the form of uniform particle size, non-uniform particle size, and capillary particles, and molded products, extrudates,
Used in molds such as ceramic rods, balls, broken strips, tiles and the like. As mentioned above, it has been disclosed that the metal catalyst according to the present invention can be used in the form of either a homogeneous catalyst or a heterogeneous catalyst. It is a preferred embodiment to use

The reaction requires the presence of an alkyl halogenide along with a metal catalyst; preferred alkyl halogenides are chlorides, bromides or iodides or mixtures thereof. ...Among the alkyl halides, it is a particularly preferred embodiment to use methyl halides such as methyl chloride, methyl bromide, and methyl iodide from the viewpoint of corrosion resistance of the reactor or separation and purification of reaction products. be. The amount of the metal catalyst used in the present invention varies depending on whether a homogeneous catalyst or a heterogeneous catalyst is used, or whether the reaction is performed in a fluidized bed or a fixed bed in the case of a heterogeneous catalyst, but in principle is applicable to any range of usage.

However, in general, 1 x 101 to 25% by weight, preferably 5 x 10-
A range of 4 to 20% by weight is selected, more preferably 1 x 10-3 to 15% by weight, but especially 2.5 x 10-
A range of 3 to 10% by weight is useful. In addition, the amount of alkyl halogenide used together with the metal catalyst is 10 per 11 based on the total volume of the reaction solution based on the halogen atom.
-3 to 15 mol, preferably 10-2 to 5 mol, more preferably 10-1 to 3 mol.

The reaction for carrying out the method of the present invention is carried out at a reaction temperature of 80 to 80°C.
It is effective to select from the range of 220°C.

The total reaction pressure may be sufficient as long as it is sufficient to maintain the reaction solution in a liquid phase and to maintain hydrogen at an appropriate partial pressure.

The preferred partial pressure of hydrogen is 0.05 to 300 atmospheres, optimally 0.
．． The partial pressure is 1 to 200 atmospheres, more preferably 0.2 to 100 atmospheres, but a wider partial pressure range of 0.01 to 500 atmospheres is also acceptable. The hydrogen used does not necessarily have to be of high purity and may contain carbon monoxide, carbon dioxide, methane, nitrogen, rare gas, etc. The raw material gas can be supplied in the form of synthesis gas (mixed gas of carbon monoxide and hydrogen). Generally, there is a strong possibility that carbon monoxide is mixed in the hydrogen gas, but carbon monoxide in the reaction gas tends to stabilize the catalyst and suppress side reactions. Therefore, 0.1 mol% or more, preferably 1
It is a preferred embodiment to mix carbon monoxide in an amount of mol % or more, more preferably 2 mol % or more. Acetic anhydride, which is a raw material of the present invention, can also be supplied by, for example, the so-called Wacker method, in which the acetic acid produced is passed through ketene as an intermediate by oxidation of acetaldehyde, or by the reaction of methanol and carbon monoxide. Alternatively, acetic anhydride produced by the reaction of methyl acetate and carbon monoxide can also be used. [For example, Japanese Patent Publication No. 52-3926, Japanese Patent Publication No. 51-65709,
Examples include JP-A-54-59214. '). In the above cases, it is expected that impurities such as acetic acid and acetic acid methylacetaldehyde will be mixed into the raw materials.
As long as the overall balance of the reaction is not disturbed, the above-mentioned impurities can be tolerated and the reaction can be carried out suitably. In addition, when acetic anhydride produced by the carbonylation reaction of methyl acetate is used as a raw material, synthesis gas is used as the raw material gas in the carbonylation reaction, and part or all of the reaction waste gas in this step is used as the hydrogen gas in the present invention. It can also be used as a raw material gas for chemical reactions. Furthermore, it is a reasonable embodiment to reuse part or all of the reaction waste gas in the hydrogenation reaction step in the carbonylation reaction step, thereby reusing the raw material gas and the reaction waste gas. Furthermore, acetic anhydride according to the above method is produced using an alkyl halide such as methyl iodide as a cocatalyst. It can also be used as part or all of a catalyst. Furthermore, in the reaction process of the present invention, it is a reasonable embodiment to reuse part or all of the halogenated alkyl catalyst in the carbonylation reaction process, and to mutually reuse the halogenated alkyl catalyst. It is. The presence of water in reaction materials is a common phenomenon, but hydrogen and acetic anhydride can tolerate the presence of a small amount of water, which is often present in commercially available reactants, without causing any problems. . However, the presence of 10 mol% or more of water in one or more of the reaction raw materials used in the present invention should generally be avoided, as introducing too much water into the reaction system may lead to decomposition of the raw materials and products. easy. In this respect, it is desirable that the water content be 5 mol% or less, more preferably 3 mol% or less. Since water is not a reaction product, maintaining near-anhydrous conditions in the reaction solution is easily accomplished by maintaining proper dryness of the necessary reactants introduced into the reaction zone as well as the reaction working fluid. Ru. In the method of the present invention, the raw material acetic anhydride and/or the reaction intermediate ethylidene diacetate itself also serves as a reaction solvent, so a solvent does not necessarily need to be used, but it is necessary to use a solvent that is compatible with the raw materials and products in the reaction environment. It is also possible to use organic solvents and diluents.

The preferred solvent used is a substance that participates in the reaction as a catalyst, raw material, reaction intermediate, product or by-product;
Examples include methyl iodide, acetic anhydride, ethylidene diacetate, acetaldehyde and methyl acetate. Among these, acetic anhydride and/or saturated aliphatic carboxylic acid alkyl esters represented by methyl acetate, which are raw materials of the present invention, are particularly preferred solvents and act effectively on the reaction of the present invention.

In this regard, 10 mmol/I or more, preferably 102 mmol/I? As mentioned above, it is a preferred embodiment that acetic anhydride and/or saturated aliphatic carboxylic acid alkyl ester represented by methyl acetate are present in an amount of 2×10 2 mmol/l or more. In the present invention, in addition to the above-mentioned solvent, a diluent compatible with the solvent can be used in combination.

Commonly usable diluents include ethylene glycol diacetate, propylene glycol diacetate, dimethyl adipate, methyl benzoate, ethyl benzoate, dimethyl phthalate, diethyl phthalate, dioctyl phthalate, phenyl acetate, Organic acid esters such as tolyl acetate, hydrocarbons such as dodecane, hexadecane, benzene, and naphthalene biphenyl, and inorganic acid esters such as triphenyl phosphate, tricresyl phosphate, dibutylphenyl phosphate, tetramethyl orthosilicate, and tetrabutyl silicate. , aromatic ethers such as diphenyl ether, and ketones such as acetone, methyl ethyl ketone, dibutyl ketone, methyl isobutyl ketone, acetophenone and benzophenone. The method of the invention can be carried out batchwise, semi-batchwise or continuously.

Further, in the case of a heterogeneous catalyst, the reaction type can be carried out in either a fluidized bed type or a fixed bed type. In the method of the present invention, the reaction liquid is in the state of a mixed liquid mainly consisting of the rogogenated alkyl catalyst, the raw material acetic anhydride, the reaction intermediate, ethylidene diacetate, the target product vinyl acetate, and the by-product acetic acid. It is important to separate the produced vinyl acetate from the reaction solution and maintain a low concentration of vinyl acetate in the reaction system, which has the property of causing a polymerization reaction.

Therefore, by separating the product, for example by distillation, the concentration of vinyl acetate in the reaction solution can be reduced to 25% by weight or less based on the reaction solution.
It is preferably kept at a concentration of 15% by weight or less, more preferably 10% by weight or less, but it is particularly effective to maintain a concentration of 5% by weight or less. Similarly, in the reaction of the present invention, it is necessary to avoid a large excess of acetic acid, which is a by-product, remaining in the reaction system, as this tends to inhibit the production of the desired product.

Therefore, the concentration of acetic acid in the reaction solution is 50% of the reaction solution.
It is particularly effective to keep the concentration below 20% by weight, preferably below 40% by weight, more preferably below 30% by weight. In order to effectively separate vinyl acetate and acetic acid from the reaction solution described above, evaporation removal can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing will be better understood by reference to the drawings, which show, by way of example only, illustrations of typical reaction and separation systems for carrying out the process of the invention.

In FIG. 1, reaction zone 10 comprises one or more pressure reactors of any type containing a suitable catalyst, typically palladium in combination with methyl iodide. Introduce liquid.

A raw material gas containing hydrogen is pressurized into the lower part of the reaction zone 10 via 11, and acetic anhydride is introduced from 12. The reacted and unreacted effluents passing through the reaction zones 10 to 13 are separated into their main components by a separation zone 20 consisting of one or more distillation units, such as flash devices and/or fractionation columns.
will be introduced in The high boiling components of the reaction mixture containing essentially non-volatile catalyst components are recycled to reaction zone 10 via 21. The low-boiling components in the reaction mixture consisting of acetaldehyde, methyl iodide, methyl acetate, vinyl acetate, acetic acid, etc. are introduced via 22 into a separation zone 30 consisting of one or more distillation units. Acetaldehyde, methyl iodide and methyl acetate pass through 33 to reaction zone 10.
The crudely separated vinyl acetate and acetic acid that are circulated to the reactor 31 or 32 are extracted simultaneously or separately. Next, a preferable method different from the above method will be explained. In FIG. 2, reaction zone 100 comprises one or more pressure reactors of any type containing a reaction solution containing a suitable catalyst, typically palladium in combination with methyl iodide. will be introduced. Raw material gas is forced into the lower part of the reaction zone 100 from 101 via 103 together with a circulating gas stream 109, and acetic anhydride is introduced from 102. reaction zone 100
In order to separate the effluent stream from 105 through 105, i.e. the reacted and unreacted effluent vapor stream containing the reactant gas, into its main components, a gas-liquid separator with more than Separation zone 2 consisting of and distillation unit
Introduced in 00. That is, the effluent vapor stream containing hydrogen passes through 105 and is separated into gas and liquid at separation zone 200 . A gas stream containing non-condensable hydrogen is circulated through 108 to 109, along with the feed gas from 101, to reaction zone 100 via 103, and is discharged to 110 out of the saw system if necessary. Sometimes. Meanwhile, components such as acetaldehyde, methyl iodide, methyl acetate, vinyl acetate, and acetic acid are separated into gas and liquid by stripping and/or evaporation in the separation zone 200 via stripping and/or evaporation 105, but acetic acid, acetic anhydride, etc. A portion of, or most of the components such as acetaldehyde, methyl iodide, methyl acetate, etc., are recycled to reaction zone 100 with the reactant gas stream. On the other hand, the effluent containing vinyl acetate and acetic acid separated into gas and liquid by the separation zone 200 is introduced into the separation zone 300 via 107. Low-boiling components mainly consisting of methyl acetate and methyl iodide are circulated from 300 to 303 to reaction zone 100, and high-boiling components mainly consisting of acetic anhydride and ethylidene diacetate are circulated from 300 to 304 to reaction zone 1.
Cycled to 00. Vinyl acetate and acetic acid, which are the target products, are extracted together or separately from 301 or 302. A portion of the reaction liquid in the reaction zone to prevent the accumulation of high-boiling point by-products (such as by-product polymers, etc.) that may be generated during the reaction, or to extract a portion of the catalyst. may be purged from 104.

The method of the present invention, which has been described in detail above, produces vinyl acetate by reacting acetic anhydride with hydrogen through a novel reaction, and has extremely high industrial significance.

This will be explained in more detail below with reference to Examples. Reference Example 1 135y of acetic anhydride, 15y of methyl iodide, and 4.57% of 5% palladium activated carbon (manufactured by Kawaken Fine Chemicals, commercial product PM type) were placed in a pressure-resistant reactor, and mixed gas of hydrogen and carbon monoxide (2:1) was added. using gauge pressure 50k9/Crl
i. The reaction was carried out at 175°C for 30 minutes.

Along with a corresponding amount of acetic acid, vinyl acetate 0.778y1 ethylidene diacetate 88.0y, acetaldehyde 1.27y.
y was generated.

Reference Example 2 Acetic anhydride 1007, methyl acetate 35V, methyl iodide 157 and 4.5t of 5% palladium activated carbon (manufactured by Nippon Engel-Ruth, commercial product) were put into a pressure-resistant reactor, and after pressurizing to a hydrogen gauge pressure of 30kg/Cwi. , heated to 175℃, and at this temperature, while supplementing hydrogen, the gauge pressure was increased to 50k9/C.
d and stirred for 30 minutes.

Vinyl acetate 2.58f, ethylidene diacetate 22.97, acetaldehyde 0.288, along with a considerable amount of acetic acid.
y was generated. Reference Example 3 Acetic anhydride 1357, methyl iodide 15y and 5% palladium barium sulfate (manufactured by Kawaken Fine Chemicals, commercial product) 4.57 were placed in a pressure-resistant reactor, and a mixed gas of hydrogen and carbon monoxide was pumped at a gauge pressure of 30 kg/leak. After press-fitting, heat to 17
5℃, and at this temperature, while supplementing hydrogen, the gauge pressure was increased to 50℃.
The reaction was carried out for 90 minutes while maintaining k9/CrA.

0.4157 of vinyl acetate and 14.07 of ethylidene diacetate were produced along with a considerable amount of acetic acid. Example 16 This was carried out according to the flow sheet as illustrated in FIG.

In reaction zone 10, 35% by weight of acetic anhydride, 10% by weight of methyl acetate, 10% by weight of methyl iodide, and 4% ethylidene diacetate were added.
A mixture consisting of 2% by weight and 3% by weight of 5% palladium on activated carbon was charged to a predetermined liquid level, replaced with a mixed gas of hydrogen and carbon monoxide (volume ratio 2:1), and then heated to a temperature of 175°C. Thereafter, a mixed gas having the above composition was injected from the lower part 11 of the reaction zone to 30 kg/CdG, and while hydrogen was being supplied from 11, the mixture was maintained at 30 kg/CniG and stirred for 3 hours.
Next, the movement of the liquid was started and acetic anhydride was added from 12 to 13 so that the average residence time in the reaction zone was 3 hours.
．． Replenishment was carried out at a rate of 8f7/hour, and hydrogen was replenished from 11 to maintain the total pressure at 30k9/Crii. At the same time, the reaction mixture was flash-distilled via 13 in a separating zone 20, and the low-boiling components containing 5.22% by weight of vinyl acetate were led via 22 to a separating zone 30 containing a rectifier. High boiling components and catalyst were recycled to reaction zone 10 via 20 to 21. Low-boiling components mainly consisting of methyl acetate and methyl iodide are circulated from 30 to reaction zone 10 via 33,
Further, high-boiling components mainly consisting of acetic anhydride and ethylidene diacetate were circulated to reaction zone 10 via 30 to 34. The product vinyl acetate was taken out through separation zones 30 and 32 at a rate of 5.47 y/hour, and acetic acid was taken out through separation zones 31 at a rate of 8.117 y/hour. At the end of the reaction, the amount of ethylidene diacetate in the reaction zone was 44% by weight.

The yield of vinyl acetate based on acetic anhydride is calculated to be 94.0%.

Example 17 This was carried out according to the flow sheet as illustrated in FIG.

A mixture consisting of 35% by weight of acetic anhydride, 10% by weight of methyl acetate, 10% by weight of methyl iodide, 42% by weight of ethylidene diacetate and 3% by weight of 5% palladium on activated carbon is placed in a reaction zone 100 containing a pressure-resistant reactor at a predetermined liquid level. Charge up to
After replacing the gas with a mixed gas of hydrogen and carbon monoxide (volume ratio 3:l), it was heated to a temperature of 175°C. Thereafter, a mixed gas having the above composition was injected from the lower part of the reactor to 30 kg/Cd, and while hydrogen was being replenished from 101, it was maintained at 30 k9/CrAG and stirred for 3 hours. Next, the movement of gas and liquid was started and the average residence time in the reaction zone was 3 hours.
Acetic anhydride was replenished from 02 at a rate of 14.77/hour, and hydrogen was introduced from 101 to maintain the total pressure at 30 k9/Cd. At the same time, gas circulation was carried out through lines passing through reaction zones 100 to 105 and separation zones 200, 108, 109, 103 containing distillation units. The effluent containing 6.8% by weight of vinyl acetate, which was fractionated at 100° C. in the separation zone 200, was led through 107 to the separation zone 300 containing a rectification device. Low-boiling components mainly consisting of methyl acetate and methyl iodide are circulated from 300 to 303 to reaction zone 100, and high-boiling components mainly consisting of acetic anhydride and ethylidene diacetate are circulated from 300 to 304 to reaction zone 10.
It cycled back to 0. The product, vinyl acetate, is separated by a separation zone of 300
through 302 at a rate of 5.767/hour,
Acetic acid was extracted through 301 at a rate of 8.617/hour. At the end of the reaction, the ethylidene diacetate in the reaction zone is 4
It was 3% by weight.

The yield of vinyl acetate based on acetic anhydride is calculated to be 92.9%.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are illustrations of process diagrams for carrying out the method of the present invention, and the numbers in the figures are respectively 10; reaction zone, 2;
0, 30; Separation zone, 11; Raw material gas supply line, 12;
Raw material and catalyst supply line, 100: Reaction zone, 200,3
00: Separation zone, 101: Raw material supply line, 102: Raw material and catalyst supply line.

Claims (1)

[Claims] 1. In the presence of palladium and/or its compound and an alkyl halide which is a chloride, bromide and/or iodide, acetic anhydride and hydrogen are reacted while vinyl acetate and acetic acid are separated to form acetic acid. A method for producing vinyl, wherein a portion of the reaction mixture is extracted from the reaction zone, vinyl acetate and acetic acid are separated therein, and the remaining components, including alkyl halides, acetic anhydride and ethylidene diacetate, are transferred to the reaction zone. A method for producing vinyl acetate, characterized by carrying out the reaction while circulating. 2. The method of claim 1, wherein the alkyl halide is selected from the group consisting of methyl chloride, methyl bromide, and methyl iodide.