DESCRIPTION

METHOD OF PRODUCING N-PROPYL ACETATE AND ALLYL ACETATE

TECHNICAL FIELD [0001]

The present invention relates to a method of producing n-propyl acetate and allyl acetate.

The present application claims priority on Japanese Patent Application No. 2007-295709 filed in Japan on November 14, 2007, the content of which is incorporated herein by reference.

BACKGROUND ART [0002]

Saturated esters such as n-propyl acetate, isobutyl acetate and n-butyl acetate have conventionally been commonly used as solvents and reaction solvents and are industrially important compounds. These saturated esters are typically produced by an esterification reaction resulting from condensation of a corresponding alcohol and carboxylic acid. However, in such esterification reactions, the reaction equilibrium is unable to be shifted to the product (ester) side unless the by-product in the form of water is removed outside the system, thereby making it industrially difficult to obtain a high raw material conversion rate and reaction rate. Since the latent heat of vaporization of water is much higher than that of other organic compounds, there is also the difficulty of consuming a large amount of energy when separating by vaporization

of water. [0003]

On the other hand, unsaturated esters, which contain an unsaturated group such as an allyl group, methacrylic group or vinyl group, in the alcohol portion of an ester, can be produced industrially by going through, for example, an oxidative carboxylation reaction with a corresponding olefin and carboxylic acid. hi particular, unsaturated group-containing esters are commonly known to be able to be produced by reacting a corresponding olefin, oxygen and carboxylic acid in the presence of a palladium catalyst while in the vapor phase, and there are numerous known documents regarding their production. For example, Japanese Unexamined Patent Application, First Publication No. H2-91045 describes that allyl acetate can be produced industrially at extremely high yield and high space-time yield by reacting propylene, oxygen and acetic acid in the presence of a palladium catalyst in the vapor phase. [0004]

In addition, a method of producing allyl alcohol is described in Japanese Unexamined Patent Application, First Publication No. H2 -49743 in which allyl acetate obtained according to the above-mentioned methods is hydrolyzed using a cation exchange resin. Moreover, Japanese Unexamined Patent Application, First Publication No. S62-149637 describes a method of producing 70% by weight of ally alcohol by purification and separation of allyl alcohol obtained in this manner. According to these documents, methods of producing allyl alcohol by hydrolyzing allyl acetate have a low reaction equilibrium constant of 0.39, and are described to use three distillation columns and one extraction column to purify and separate a reaction mixture comprised

mainly of allyl alcohol, allyl acetate, acetic acid and water following hydrolysis of allyl acetate. Namely, it is described that, among the four components of allyl alcohol, allyl acetate, acetic acid and water, acetic acid and other high boiling point components are separated and removed from the bottom of the first distillation column, and in the subsequent extraction column, allyl acetate is extracted and separated from the top of the extraction column from a mixture comprised mainly of allyl alcohol, allyl acetate and water obtained from the top of the first distillation column with water obtained from the bottom of the third distillation column, while in the second distillation column, allyl acetate remaining in the bottom liquid of the extraction column is distilled and separated, and the bottom liquid thereof is distilled and separated in the third distillation column, thereby resulting in the obtaining of 70% by weight of allyl alcohol in the form of an azeotropic composition with water from the top of the column. [0005]

In the above process, the liquid at the top of the extraction column is a mixture comprised mainly of allyl acetate, and this liquid is described in the aforementioned document to be recycled to the hydrolysis step described above.

There are numerous known documents describing the hydrogenation of unsaturated group-containing esters containing allyl acetate. Japanese Unexamined Patent Application, First Publication No. H9- 194427 discloses a method of producing n-propyl acetate by hydrogenating allyl acetate using a nickel catalyst. In addition, Japanese Unexamined Patent Application, First Publication No. 2000-064852 describes a method of producing n-propyl acetate by using, for example, a silica-supported palladium catalyst, alumina-supported palladium catalyst or sponge nickel catalyst. According to the above documents, an allyl acetate conversion rate of nearly 100% can

be achieved while also achieving n-propyl acetate selectivity of 99.0% or more. In addition, a reaction method is also described in which a portion of the n-propyl acetate formed is recycled to a hydrogenation reactor to remove the considerable amount of reaction heat generated accompanying the hydrogenation reaction, and it is also described that acetic acid selectivity increases while n-propyl acetate selectively decreases if this is not carried out. [0006]

Allyl alcohol is produced industrially by producing allyl acetate using propylene, oxygen and acetic acid as raw materials and using a palladium catalyst and the like, followed by subjecting to a hydrolysis reaction using a cation exchange resin and the like. In this industrial production process, the product allyl alcohol is obtained in the form of a 70% by weight aqueous solution of allyl alcohol, n-propyl acetate can be obtained by hydrogenating (also referred to as a hydrogen addition reaction or hydrogenation reaction) the intermediate process liquid of this allyl alcohol production process in the form of highly concentrated allyl acetate.

DISCLOSURE OF THE INVENTION [0007]

However, since the highly concentrated allyl acetate process liquid described above contains a large number of impurities, aldehydes and colored components are contained in the n-propyl acetate obtained as the final product even if the separation and purification method is conducted, thereby causing considerable problems in terms of product quality.

An object of the present invention is to provide a method of producing uncolored

and highly pure n-propyl acetate and allyl acetate by removing impurities and colored components that are difficult to separate.

[0008]

As a result of conducting extensive studies to solve the aforementioned problems, the inventors of the present invention were able to decolor an allyl acetate process liquid by subjecting the allyl acetate process liquid containing impurities to photoirradiation, and preferably combining with the use of an adsorption procedure, and able to decompose aldehydes or unsaturated group-containing esters, which are difficult to separate by distillation from n-propyl acetate, by subjecting n-propyl acetate liquid containing impurities to ozone treatment following hydrogenation, and able to obtain highly pure n-propyl acetate by a subsequent distillation procedure. Namely, the present invention relates to the following [1] to [8]. [0009]

[1] A method of producing n-propyl acetate comprising: producing allyl acetate by using propylene, oxygen and acetic acid as raw materials, and subsequently carrying out a hydrogenation reaction by using the allyl acetate as raw material that is an intermediate of a process for producing allyl alcohol by hydrolyzing the allyl acetate; wherein, the method comprises a photoirradiation treatment step and/or ozone treatment step.

[2] The method of producing n-propyl acetate described in [1] above, wherein the allyl acetate has a Hazen value of 80 or more, and the total amount of 2-methylcroton aldehyde and 2-methylbutanal is 500 ppm by weight or more.

[3] The method of producing n-propyl acetate described in [1] or [2] above, wherein the photoirradiation treatment is carried out before the hydrogenation reaction.

[4] The method of producing n-propyl acetate described in any of [1] to [3] above, wherein the photoirradiation wavelength of the photoirradiation treatment contains the region of 400 to 450 run.

[5] The method of producing n-propyl acetate described in [1] or [2] above, wherein the ozone treatment is carried out after the hydrogenation reaction.

[0010]

[6] The method of producing n-propyl acetate described in [1] or [2] above, wherein

1) allyl acetate is formed by using propylene, oxygen and acetic acid as raw materials,

2) allyl alcohol and acetic acid are formed by hydrolyzing the allyl acetate, 3) acetic acid in the hydrolysis reaction liquid is separated in a first distillation column and all or a portion of the liquid in the column bottom is recirculated to the step 1), 4) the liquid in the top of the first distillation column is separated into two phases of an aqueous layer and an oily layer, and the oily layer containing allyl alcohol is supplied to an extraction column, 5) allyl alcohol in the oily layer is extracted with an extraction column by using the liquid in the bottom of a third distillation column as extracting water, and liquid in the top of the column comprised mainly of allyl acetate is recirculated to the step 2), and 6) low boiling point components contained in the liquid in the bottom of the extraction column are separated and removed from the top of a second distillation column, water contained in the liquid in the bottom of the column is separated and removed from the bottom of the third distillation column, and a portion of the liquid in the top of the extraction column in a process for obtaining allyl alcohol of an azeotropic composition with water from the top of the third distillation column is used allyl acetate as raw material.

[7] The method of producing n-propyl acetate described in any of [1] to [5] above,

wherein the method comprises a decoloration step using adsorption prior to the hydrogenation reaction.

[8] A method of producing allyl acetate comprising: producing allyl acetate by using propylene, oxygen and acetic acid as raw materials, and subsequently carrying out photoirradiation treatment on allyl acetate that is an intermediate of a process for producing allyl alcohol by hydrolyzing the allyl acetate.

[0011]

According to the method of producing n-propyl acetate and allyl acetate of the present invention, highly pure and uncolored n-propyl acetate and allyl acetate can be produced at the same time in a process for producing allyl alcohol by using propylene, oxygen and acetic acid as raw materials thereof.

BRIEF DESCRIPTION OF THE DRAWINGS [0012]

Fig. 1 is a drawing showing the production process of allyl alcohol.

Fig. 2 is a drawing showing the production process of n-propyl acetate.

Fig. 3 is a drawing showing the absorbance spectra of samples of Example 3. [0013]

(Brief description of the reference symbols)

1: propylene, 2: oxygen, 3: acetic acid, 4: reactor outlet gas, 5: absorption column bottom liquid, 6: hydrolysis reactor feed liquid, 7: hydrolysis reactor reaction liquid, 8: oily layer, 9: first distillation column bottom liquid, 10: extraction column top liquid, 11 : extraction column bottom liquid, 12: second distillation column bottom liquid, 13: third distillation column bottom liquid, 14: allyl alcohol product, 15: portion of extraction column top liquid, 16: fourth distillation column distillate, 17: hydrogenation

reactor feed liquid: 18: hydrogenation reactor circulating liquid, 19: hydrogenation reaction liquid, 20: ozone treated liquid, 21: n-propyl acetate product, 22: fourth distillation column bottom liquid, 23: fourth distillation column top liquid, 24: fifth distillation column bottom liquid, 25: fifth distillation column top liquid, 26: feed gas, 27: aqueous layer, 31: reactor, 32: absorption column, 33: hydrolysis reactor, 34: first distillation column, 35: extraction column, 36: second distillation column, 37: third distillation column, 38: fourth distillation column, 39: photoirradiation equipment, 40: hydrogenation reactor, 41: ozone treatment equipment, 42: fifth distillation column, 43: decanter, 44: intermediate tank, 45: acetic acid water vaporizer.

BEST MODE FOR CARRYING OUT THE INVENTION [0014]

The following provides a detailed explanation of an embodiment of the present invention with reference to Figs. 1 and 2,

<Process for Producing 70% by weight of Allyl Alcohol Using Propylene, Oxygen and Acetic Acid as Raw Materials>

(Production of Allyl Acetate)

The reaction formula during production of allyl acetate from propylene, oxygen and acetic acid is indicated below.

[Formula 1]

CH ₂ =CH-CH ₃ + 1/2O ₂ + CH ₃ COOH → CH ₂ =CH-CH ₂ -OCOCH ₃ + H ₂ O

There are no particular limitations on the propylene raw material in the process for producing allyl acetate. Although lower saturated hydrocarbons such as propane or ethane may also be present, the highly pure propylene is preferable used.

Moreover, there are also no particular limitations on the oxygen. The oxygen may be diluted with an inert gas such as nitrogen or carbon dioxide gas, and air, for example, may be used. However, in the case of circulating reaction gas, highly pure oxygen, and particularly oxygen having a purity of 99% or more, is preferably used. [0015]

Any catalyst may be used for the catalyst provided it has the ability to obtain allyl acetate by reacting propylene, acetic acid and oxygen. The catalyst is preferably a supported solid catalyst containing the following components (a) to (c):

(a) palladium;

(b) a compound having at least one type of element selected from the group consisting of copper, lead, ruthenium and rhenium; and

(c) at least one type of compound selected from the group consisting of an alkaline metal acetate and alkaline earth metal acetate.

[0016]

Although palladium of any valence may be used for the component (a), metal palladium is preferable. The "metal palladium" as referred to here is palladium having a valence of 0. Metal palladium can be typically obtained by reducing palladium ions having a valence of 2 and/or 4 using a reducing agent in the form of hydrazine or hydrogen and the like. At this time, all of the palladium is not required to be in the metal state.

There are no particular limitations on the raw material of the component (a). In addition to naturally being able to use metal palladium, a palladium salt able to be converted to metal palladium can also be used. Examples of palladium salts able to be converted to metal palladium include, but are not limited to, palladium chloride,

palladium sodium chloride, palladium nitrate and palladium sulfate.

The ratio between the support and the component (a) (support : component (a)) in terms of a weight ratio is preferably 1 :0.1 to 5.0 and more preferably 1 :0.3 to 1.0. [0017]

A soluble salt such as a nitrate, carbonate, sulfate, organic acid salt or halide having at least one type of element selected from the group consisting of copper, lead, ruthenium and rhenium can be used for the component (b). Among these, chlorides are preferable since they are easy to acquire and have superior water solubility. In addition, a preferable example of an element among the aforementioned elements is "copper". Examples of copper chlorides include, but are not limited to, cuprous chloride, cupric chloride, copper acetate, copper nitrate, copper acetylacetonate and copper sulfate.

The ratio between the component (a) and the component (b) (component (a) : component (b)) in terms of a molar ratio is preferably 1 :0.05 to 10 and more preferably 1:0.1 to 5. [0018]

A preferable example of the component (c) is an alkaline metal acetate, specific examples of which include lithium acetate, sodium acetate and potassium acetate. Sodium acetate and potassium acetate are more preferable, while potassium acetate is the most preferable.

Although there are no particular limitations on the loaded amount of alkaline metal acetate, the loaded amount is preferably 1 to 30% by weight based on the catalyst. In addition, in order to achieve a desired loaded amount, an acetate of an alkaline metal may be added to reactor by a method such as adding it to a feed gas in the form of an

aqueous solution or acetic acid solution. [0019]

There are no particular limitations on the support used to load the catalyst component, and may be a porous substance typically used as a support. Preferable examples of supports include silica, alumina, silica-alumina, diatomaceous earth, montmorillonite and titania, while silica is more preferable. In addition, there are no particular limitations on the form of the support. Specific examples of support forms include, but are not limited to, powders, spheres and pellets.

Although there are no particular limitations on the particle diameter of the support, it is preferably 1 to 10 mm and more preferably 3 to 8 mm. In the case of carrying out a reaction by filling the catalyst into a tubular reactor, if the particle diameter is less than 1 mm, large pressure loss occurs when gas is allowed to flow through the reactor, thereby resulting in the risk of being unable to effectively circulate the gas. In addition, if the particle diameter exceeds 10 mm, reaction gas is unable to diffuse to the inside the catalyst, thereby resulting in the risk of the catalyst reaction no longer proceeding effectively.

The pore structure of the support is such that the pore diameter is preferably 1 to 1000 nm and more preferably 2 to 800 nm. [0020]

There are no particular limitations on the method used to load components (a), (b) and (c) onto the support, and any method may be used.

More specifically, a method may be used in which an aqueous solution of component (a) in the form such as a palladium salt and component (b) is impregnated into a support followed by treating with an aqueous solution of an alkaline metal salt.

At this time, alkaline treatment is preferably carried out without drying the support in which the catalyst liquid is impregnated. The treating time with an aqueous solution of an alkaline metal salt is the amount of time required for the salt of the catalyst component impregnated in the support to be completely converted to a compound insoluble in water, and normally 20 hours is adequate. [0021]

Next, the metal salt of the catalyst component precipitated on the surface layer of the catalyst support is treated with a reducing agent to obtain a metal of valence zero. The reduction is carried out in a liquid phase by adding a reducing agent such as hydrazine or formalin. Subsequently, the catalyst support is rinsed with water until chlorine ions and the like are no longer detected, followed by drying, loading an alkaline metal acetate and drying further. Although loading can be carried out by the method described above, it is not limited thereto. [0022]

There are no particular limitations on the reaction type used when carrying out the reaction between acetic acid, propylene and oxygen in the presence of catalyst, and a known reaction type of the prior art can be selected. In general, there is a method optimal for the catalyst used, and such reaction type is preferably carried out. In the case of using a supported solid catalyst of the present invention, a fixed bed flow reaction in which the catalyst is filled into a reactor is advantageously used in terms of practical use.

Although there are no particular limitations on the material of the reactor, the reactor is preferably comprised of a material having corrosion resistance.

There are no particular limitations on the reaction temperature when producing

allyl acetate, and the temperature is preferably 100 to 300 ⁰ C and more preferably 120 to 25O ⁰ C.

Although there are no particular limitations on the reaction pressure, from the viewpoint of the equipment, a pressure of 0.0 to 3.0 MPaG is practically advantageous, while a pressure of 0.1 to 1.5 MPaG is more preferable. [0023]

The reaction raw material gas contains acetic acid, propylene and oxygen, and nitrogen gas, carbon dioxide gas or a rare gas can be further used as a diluent as necessary. Acetic acid is supplied to the allyl acetate formation reactor in an amount at a ratio of 4 to 20 vol% and preferably 6 to 10 vol%, and propylene is supplied in an amount at a ratio of 5 to 50 vol% and preferably 10 to 40 vol%, based on the total amount of reaction raw material gas.

The ratio among acetic acid, propylene and oxygen (acetic acid : propylene : oxygen) in terms of a molar ratio is preferably 1 :0.25 to 13:0.15 to 4 and more preferably 1:1 to 7:0.5 to 2.

The reaction raw material gas is preferably passed through the catalyst in the standard state at a spatial velocity of 10 to 15,000 hr ^"1 and particularly preferably at a spatial velocity of 300 to 8,000 hr ^"1 . [0024]

As shown in Fig. 1, in a process for producing allyl acetate, propylene 1, oxygen 2 and acetic acid 3 are supplied as raw materials, and allyl acetate is produced under the previously described reaction conditions in a reactor 31 filled with the aforementioned catalyst. Reactor outlet gas 4, which contains allyl acetate that has left reactor 31 , is sent to an absorption column 32. In addition, a portion of a first distillation column

bottom liquid 9 comprised mainly of acetic acid and water is sent to the absorption column 32 in the form of an absorbing liquid. In the absorption column 32, a condensed component contained in the reactor outlet gas 4 is absorbed into the absorbing liquid to obtain an absorption column bottom liquid 5 comprised mainly of allyl acetate, acetic acid and water. Absorption column bottom liquid 5 becomes hydrolysis reactor feed liquid 6 following being combined with an extraction column top liquid 10, a fourth distillation column bottom liquid 22 and a fourth distillation column top liquid 23 in an intermediate tank 44, which is then supplied to a hydrolysis reactor 33. On the other hand, a non-condensed component comprised mainly of propylene, oxygen and carbon dioxide gas contained in the reactor outlet gas 4 is recirculated from the top of the absorption column 32 to the reactor 31 in the form of a reaction raw material. [0025]

(Production of Allyl Alcohol by Hydrolysis of Allyl Acetate) The following provides an explanation of a process for obtaining allyl alcohol by hydro lyzing the reaction mixture comprised mainly of allyl acetate obtained according to the process described above.

The reaction formula during production of allyl alcohol from allyl acetate by hydrolysis is indicated below. [Formula 2]

CH ₂ =CH-CH ₂ -OCOCH ₃ + H ₂ O → CH ₂ =CH-CH ₂ OH + CH ₃ COOH Although the pressure of the hydrolysis reaction is not limited in any way, the reaction can be carried out at the pressure of, for example, 0.0 to 1.0 MPaG Moreover, although any temperature may be used for the reaction temperature, the reaction

temperature is preferably 20 to 300 ⁰ C and more preferably 50 to 25O ⁰ C to obtain an adequate reaction rate.

There are no particular limitations on the type of hydrolysis reaction, and the reaction can be carried out in the form of a gas phase reaction, liquid phase reaction or liquid-solid reaction. The reaction is preferably carried out in the form of a gas phase reaction or liquid phase reaction.

[0026]

There is a reaction equilibrium between the raw material compounds of the hydrolysis reaction in the form of allyl acetate and water and the products of the hydrolysis reaction in the form of allyl alcohol and acetic acid, and in order to obtain an adequate allyl acetate conversion rate, it is preferable to carry out the hydrolysis reaction by adding water. Although there are no particular limitations on the amount of water added, the concentration of water hi the raw materials is preferably 1.0 to 60% by weight and more preferably 5 to 40% by weight, hi addition, the reaction is preferably carried out while removing products outside the reaction system as needed by using commonly known methods so that the reaction equilibrium is advantageously shifted to the products side. Although there are no particular limitations on the method used to remove products outside the reaction system, an example of such method includes adding a component that forms an azeotropic mixture with allyl alcohol in the manner of reactive distillation and then removing the allyl alcohol outside the reaction system while distilling as the reaction proceeds. [0027]

Li the hydrolysis reaction, although it is possible to carry out a hydrolysis reaction of allyl acetate with only raw material compounds in the form of allyl acetate and water

and products in the form of acetic acid and allyl alcohol, it is preferable to carry out hydrolysis of allyl acetate in the presence of an ester hydrolysis catalyst in order to obtain an adequate reaction rate.

Examples of ester hydrolysis catalysts able to be used in the present invention include, but are not limited to, acidic substances and basic substances.

Although there are no particular limitations on the acidic substances, preferable examples include organic acids, inorganic acids, solid acids and salts thereof. Specific examples of organic acids include formic acid, acetic acid, propionic acid, tartaric acid, oxalic acid, butyric acid, terephthalic acid and fumaric acid; specific examples of inorganic acids include heteropolyacid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrobromic acid and hydrofluoric acid; specific examples of solid acids include silica-alumina, silica-titania, silica-magnesia and acidic cation exchange resins, and specific examples of salts thereof include sodium salts, potassium salts, magnesium salts and aluminum salts.

Although there are no particular limitations on the basic substances, preferable examples include sodium hydroxide, potassium hydroxide, magnesium hydroxide, magnesium oxide, calcium oxide and alkaline anion exchange resins. Similar to the case of acidic substances, these basic substances may be used alone or two or more types may be used as a mixture. [0028] hi the allyl acetate hydrolysis process, it is necessary to separate the catalyst, allyl alcohol and acetic acid after the reaction. hi the case of using a homogeneous catalyst such as sulfuric acid for the hydrolysis catalyst, it is necessary to separate the allyl alcohol, acetic acid and sulfuric

acid from the homogeneous reaction mixture and considerable energy is required for this purpose.

On the other hand, in the case of a heterogeneous catalytic reaction using a solid catalyst as exemplified by an acidic cation exchange resin, the catalyst, allyl alcohol and acetic acid can be separated from the reaction mixture by a simple method such as filtration, thus making this more preferable as an allyl acetate hydrolysis catalyst, hi addition, in addition to solid catalysts such as the acidic cation exchange resins as mentioned above having high acidity and favorable rate of allyl acetate hydrolysis, they also have a long catalyst life making them the most preferable as hydrolysis catalysts.

Examples of the acidic cation exchange resins include sulfonated copolymers of styrene and divinylbenzene. [0029]

Although there are no particular limitations on the reactor used in the hydrolysis reaction (reactor 33 in Fig. 1), a fixed bed flow reactor is preferable. The use of a fixed bed flow reactor makes it possible to easily obtain a reaction mixture from the reactor outlet that does not contain acidic cation exchange resin while retaining the acidic cation exchange resin in the reactor. [0030]

There are no limitations on the method used to produce allyl alcohol by a fixed bed flow reactor using an acidic cation exchange resin for the hydrolysis catalyst. Reaction raw material liquid containing allyl acetate and water (hydrolysis reactor feed liquid 6 in Fig. 1) may be passed through the reactor by downsward flow from the upper portion of the fixed bed flow reactor, or the reaction raw material liquid may be passed through the reactor by upward flow from the lower portion of the fixed bed flow reactor.

In general, it is preferable to allow the reaction raw material liquid to pass through the reactor by downward flow from the upper portion of the reactor. The use of this method eliminates the need for a pump or other power source in comparison with the method in which the reaction raw material liquid is passed through the reactor by upward flow from the lower portion of the reactor since the raw material reaction liquid is able to pass through the reactor by its own weight.

However, in the case of using a method in which the reaction raw material liquid is allowed to pass through the reactor downward from the upper portion of the reactor, there is the risk of the occurrence of aggregation of the ion exchange resin, decreased reaction rate due to drift of the reaction raw material liquid and the like, or increased pressure loss within the reactor depending on the conditions thereof. As a simple method for suppressing or eliminating these phenomena, it is effective and preferable to cause the reaction raw material liquid to temporarily pass through the reactor by upward flow from the lower portion of the reactor. hi addition, the use of two or more reactors in parallel is more preferable from the viewpoint of being able to continuously obtain a certain amount of allyl alcohol. [0031]

Next, an explanation is provided of a process for obtaining a 70% by weight aqueous solution of allyl alcohol by purifying and separating a mixture mainly comprised of allyl alcohol, acetic acid, water and unreacted allyl acetate obtained from the hydrolysis reaction step. hi Fig. 1, a hydrolysis reactor reaction liquid 7 that has left hydrolysis reactor 33 and is mainly comprised of allyl alcohol, allyl acetate, acetic acid and water is distilled and separated into acetic acid and other high boiling point components and a mixture of

low boiling point components in the form of allyl alcohol, allyl acetate and water in a first distillation column 34. The high boiling point components are recirculated to an absorption column 32 and an acetic acid water vaporizer 45.

As a result of this distillation and separation, the mixture of low boiling point components is sent from the top of first distillation column 34 to a decanter 43 where it is separated into two layers consisting of an oily layer and an aqueous layer. An oily layer 8, which has a high content of allyl acetate, is led to an extraction column 35. Oily layer 8 becomes an extraction column bottom liquid 11 after passing through extraction column 35, subsequently the extraction column bottom liquid 11 is led to a second distillation column 36 where it is distilled, followed by a second distillation column bottom liquid 12 (mixture of water and allyl alcohol) being extracted from the bottom of second distillation column 36. A portion of extraction column top liquid 10, comprised mainly of allyl acetate obtained from the top of extraction column 35 and having a reduced concentration of allyl alcohol, is circulated to hydrolysis reactor 33, while the remainder is sent to an n-propyl acetate production process (Fig. 2) to be described later in the form of a portion of extraction column top liquid 15 (highly concentrated allyl acetate process liquid). Second distillation column bottom liquid 12 extracted from the bottom of second distillation column 36 is distilled after being led to a third distillation column 37, a concentrated 70% by weight allyl alcohol product is recovered in the form of an azeotropic mixture of water and allyl alcohol from the top of third distillation column 37, and a third distillation column bottom liquid 13 (water) extracted from the bottom of third distillation column 37 is circulated for use as extracting water of extraction column 35. [0032]

<Process for Producing Highly Pure Allyl Acetate and n-Propyl Acetate Using Highly Concentrated Allyl Acetate Process Liquid as Raw Material>

The following provides an explanation of a process for producing highly pure allyl acetate and n-propyl acetate by using an allyl acetate process liquid as raw material with reference to Fig. 2.

A portion of extraction column top liquid 15 (highly concentrated allyl acetate process liquid) is supplied to a fourth distillation column 38 where high boiling point components and low boiling point components are removed by a distillation procedure to obtain a highly pure allyl acetate mixture (fourth distillation column distillate 16) (purification step of highly concentrated allyl acetate process liquid).

Fourth distillation column distillate 16 is supplied to photoirradiation equipment 39 where photoirradiation treatment is carried in photoirradiation equipment 39 for an adequate residence time to decolor impurities unable to be removed in the distillation procedure and obtain highly pure, uncolored allyl acetate (hydrogenation reactor feed liquid 17) (decoloration step of highly pure allyl acetate mixture). Furthermore, hydrogenation reactor feed liquid 17 may also be used directly as a highly pure allyl acetate product.

After mixing hydrogenation reactor feed liquid 17 with a hydrogenation reactor circulating liquid 18, the mixture is supplied to a hydrogenation reactor 40 where n-propyl acetate is formed by a hydrogenation reaction with hydrogen gas contained in a feed gas 26 (formation of n-propyl acetate by highly pure allyl acetate mixture hydrogenation (hydrogenation step)).

A hydrogenation reaction liquid 19 containing n-propyl acetate obtained in hydrogenation reactor 40 is supplied to ozone treatment equipment 41 where impurities

are removed by ozone treatment (ozone treatment step of n-propyl acetate-containing liquid).

An ozone treated liquid 20 obtained as a result of ozone treatment is supplied to a fifth distillation column 42 where high boiling point components and low boiling point components contained in ozone treated liquid 20 are separated and removed to obtain an n-propyl acetate product 21 (purification step of n-propyl acetate). [0033]

The following provides a more detailed explanation of each of the steps described above.

(Purification Step of Highly Concentrated Allyl Acetate Process Liquid) In Fig. 1, numerous impurities are present in extraction column top liquid 10 (highly concentrated allyl acetate process liquid) comprised mainly of allyl acetate obtained from the top of extraction column 35. Examples of major impurities include C3 gases (referring to hydrocarbons having 3 carbon atoms), propanal, acrolein, isopropyl acetate, diallyl ether, isopropanol, isopropenyl acetate, 1-propenyl acetate,- n-propyl propionate, allyl propionate, 2-methylcroton aldehyde, allyl alcohol, allyl acrylate, acetic acid and water. These impurities are ordinarily contained at a total of 5 to 15% by weight in extraction column top liquid 10.

Moreover, extraction column top liquid 10 exhibits a yellow color and normally has a Hazen value of 80 or more. Here, Hazen value refers to the value of the hue of a liquid as determined in accordance with the procedure of JIS K-0071. [0034]

As shown in Fig. 2, in order to remove impurities by purifying the highly concentrated allyl acetate process liquid, a portion of extraction column top liquid 15 of

extraction column top liquid 10 is led to fourth distillation column 38 followed by the respective extraction of fourth distillation column bottom liquid 22, containing large amounts of allyl acrylate and other high boiling point components, and fourth distillation column top liquid 23, containing large amounts of allyl alcohol, water and other low boiling point components. Fourth distillation column bottom liquid 22 and fourth distillation column top liquid 23 are recycled to the previously described hydrolysis reaction step. On the other hand, fourth distillation column distillate 16 (highly pure allyl acetate mixture), comprised mainly of allyl acetate extracted from an intermediate stage of fourth distillation column 38, has an allyl acetate purity of 95% or more. In addition, although the content of 2-methylcroton aldehyde, which is a type of impurity contained in a portion of extraction column top liquid 15, is normally 0.5 to 3.0% by weight, this is reduced to about 0.1 to 1.0% by weight as a result of this distillation procedure.

Moreover, the content of 2-methylcroton aldehyde can be reduced by increasing the reflux ratio or increasing the number of plates of the distillation column, hi this case, however, running costs or equipment costs of the distillation procedure become large, thereby making this economically disadvantageous. Thus, operating fourth distillation column 38 under suitable conditions is economically advantageous in consideration of the entire process.

Furthermore, since colored components in fourth distillation column distillate 16 are also reduced together with the reduction in the concentration of 2-methylcroton aldehyde as described above by fourth distillation column 38, the Hazen value is normally about 30 to 50. [0035]

(Decoloration Step of Highly Pure Allyl Acetate Mixture) Fourth distillation column distillate 16 (highly pure allyl acetate mixture) extracted from an intermediate stage of the fourth distillation column is sent to a decoloration step by photoirradiation equipment 39 or a decoloration step by an adsorbent (not shown), resulting in a decolored, highly pure and colorless allyl acetate (hydrogenation reactor feed liquid 17).

Any light source may be used for the light source in the photoirradiation treatment, examples of which include sunlight, fluorescent lamp, mercury lamp, LED or UV. In addition, there are no particular limitations on the irradiation time or irradiation apparatus of photoirradiation treatment. However, it is advantageous in consideration of industrial productivity that the irradiation time is short and the irradiation apparatus is compact.

There are no particular limitations on the irradiation temperature or pressure during irradiation of the photoirradiation treatment, and in general, treatment is advantageously carried out in terms of energy at normal temperature and normal pressure. There are no particular limitations on the irradiation wavelength, and there are no particular problems provided a light source is used that contains a wavelength capable of lowering the Hazen value of fourth distillation column distillate 16. However, in order to make the irradiation time and the residence time of the liquid being short, it is preferable to use a light source having intensity in the wavelength band capable of effectively lowering the Hazen value as much as possible. The wavelength band that enables the Hazen value of fourth distillation column distillate 16 to be effectively lowered is 250 to 600 nm, preferably 350 to 500 run, and more preferably 400 to 450 nm. Furthermore, light other than that of a wavelength indicated above

may also be radiated from the light source. [0036]

There are no particular limitations on the adsorbent provided it is able to decolor fourth distillation column distillate 16, and examples of such adsorbents include activated alumina, silica and diatomaceous earth, with activated alumina being particularly preferable.

There are no particular limitations on the form of the adsorbent, specific examples of which include, but are not limited to, powders, spheres and pellets.

Moreover, although there are also no particular limitations on the temperature and pressure during the adsorption procedure, in general, the procedure is advantageously carried out in terms of energy at normal temperature and normal pressure.

Hydrogenation reactor feed liquid 17, mainly comprised of allyl acetate following the decoloration step, is reduced to a Hazen value of 15 or less, preferably 10 or less and more preferably 5 or less.

Furthermore, hydrogenation reactor feed liquid 17 can also be used directly as highly pure, colorless allyl acetate product. [0037]

Although the theoretical interpretation of the photoirradiation treatment or adsorbent decoloration treatment of the highly pure allyl acetate mixture is currently not necessarily clear, according to findings of the inventors of the present invention, coloration caused by ketones exemplified by 2,3-pentanedione or aldehydes exemplified by acrolein or propanal (including polymers and the like thereof) contained in trace amounts in the process liquid is presumed to be decolored due to a chemical change of the components by photoirradiation or due to removal by adsorption.

Furthermore, photoirradiation treatment may be carried out upstream or downstream from hydrogenation reactor 40 to be described later, or may also be carried out downstream from fifth distillation column 42, it is preferably carried out upstream from hydrogenation reactor 40 as shown in Fig. 2. [0038]

(Formation of n-Propyl Acetate by Hydrogenation of Highly Pure Allyl Acetate Mixture (Hydrogenation Step))

Hydrogenation reactor feed liquid 17, after having gone through the decoloration step using, for example, photoirradiation equipment 39, is next sent to hydrogenation reactor 40 where hydrogenation to allyl acetate contained in the feed liquid is carried out. The following provides a detailed explanation of the hydrogenation step carried out by hydrogenation reactor 40.

The reaction formula during production of n-propyl acetate by hydrogenation of allyl acetate is indicated below. [Formula 3]

CH ₂ =CH-CH ₂ -OCOCH ₃ + H ₂ -> CH ₃ -CH ₂ -CH ₂ -OCOCH ₃ Hydrogen gas as well as a mixture of hydrogen gas with an inert diluent gas such as nitrogen gas or a rare gas can also be used as necessary for feed gas 26 supplied to hydrogenation reactor 40. [0039]

There are no particular limitations on the hydrogen gas used in the hydrogenation reaction. Normally a commercially available hydrogen gas may be used, and in general, a highly pure gas is preferably used, hi addition, although the amount of hydrogen gas supplied is preferably equal to or greater than the theoretical amount of

hydrogen gas required to produce n-propyl acetate from allyl acetate, it is more preferably within the range of 1.1 to 3.0 times moles and particularly preferably within the range of 1.2 to 2.0 times moles the theoretical amount. If the supplied amount of hydrogen gas is equal to or less than the theoretical amount, the amount of hydrogen consumed by side reactions causes a shortage of hydrogen to be inherently used in the reaction in the case hydrogenolysis and other side reactions occur. In addition, an excessively large supplied amount of hydrogen gas is economically disadvantageous. [0040]

A catalyst containing an element selected from groups 8, 9 and 10 of the periodic table (IUPAC Inorganic Chemistry Nomenclature Revised Edition, 1989, to apply similarly hereinafter), namely iron, ruthenium, osmium, cobalt, rhodium, indium, nickel, palladium or platinum, is used preferably for the catalyst of the hydrogenation reaction (to be referred to as the hydrogenation catalyst), with palladium, rhodium, ruthenium and nickel being particularly preferable, and palladium, rhodium and ruthenium being particularly more preferable.

Although the hydrogenation catalysts indicated above may be used alone as individual elements (or compounds) or may be loaded onto a support as necessary, loading the catalyst onto a support is advantageous in terms of allowing the obtaining of a large metal surface area during contact between the hydrogenation catalyst and allyl acetate in the hydrogenation reaction in the case of using, for example, a fixed bed reaction apparatus to be described later. [0041]

A substance normally used as a catalyst support (such as a porous substance) can be used without limitation for the support. Preferable specific examples of such a

support include silica, alumina, titanium oxide, diatomaceous earth, carbon and mixtures thereof.

The support molded into the form of pellets or spheres is preferably used since it affords easier handling.

Although there are no particular limitations on the specific surface area of the support, from the viewpoint of facilitating favorable dispersion of catalyst metal, it is preferable to use a support having a large specific surface area. More specifically, the value of specific surface area as determined according to the BET method is preferably 10 to 1000 m ² /g, more preferably 30 to 800 m ² /g and particularly preferably 50 to 500 m ² /g. In addition, although there are also no particular limitations on the total pore volume of the support, it is preferably 0.05 to 6.5 ml/g, more preferably 0.1 to 5.0 ml/g and particularly preferably 0.5 to 3.0 ml/g.

There are no particular limitations on the form of the support, and the shape can be suitably selected from commonly known forms. From the viewpoint of uniformity of the pressure inside hydrogenation reactor 40, pellets, spheres, hollow cylinders, spoked wheels, a honeycomb type monolithic support having parallel flow channels or foam ceramic support with high porosity are preferable, and pellets or spheres are particularly preferable in consideration of ease of production.

In the case of bulk loading of a catalyst loaded onto a support onto a catalyst layer, the support can be used without the pressure decrease being excessively large, and in the case of bulk loading, it is preferable to have an extremely large geometrical surface area as compared with total bulk volume. In consideration of these points, the support preferably has an external size within the range of 0.5 to 5.0 mm and more preferably within the range of 1.0 to 4.5 mm.

[0042]

In the hydrogenation reaction of allyl acetate of the present invention, a lower reaction temperature is preferable since it allows hydrogenolysis reactions to be inhibited more easily. Since hydrogenation reactions generate extremely large amounts of heat (for example, 1607 kJ of heat is generated accompanying hydrogenation of 1 kg of allyl acetate), if only allyl acetate is allowed to react, the temperature within the reaction system rises considerably due to the heat generated accompanying the hydrogenation thereof, thereby resulting in the possibility of this causing hydrogenolysis reactions to be promoted. In order to suppress this extreme rise in temperature, it is preferable to carry out the hydrogenation reaction after diluting the allyl acetate with a solvent that is inert with respect to the hydrogenation reaction. Here, a "solvent that is inert with respect to the hydrogenation reaction" refers to a solvent that does not substantially affect the hydrogenation of allyl acetate in the present invention. [0043]

In the case of diluting the allyl acetate with an inert solvent as described above, the concentration of the allyl acetate is preferably within the range of 1 to 50% by weight, more preferably 3 to 30% by weight and most preferably 5 to 15% by weight.

If the concentration of allyl acetate is less than 1% by weight, although the extreme rise in temperature caused by generation of heat can be adequately suppressed, since the concentration of allyl acetate is excessively low, productivity decreases. On the other hand, if the concentration of allyl acetate exceeds 50% by weight, it is difficult to adequately suppress the extreme rise in temperature caused by generation of heat. Moreover, in the case of using an adiabatic liquid phase reaction (and particularly an

adiabatic gas-liquid two-phase flow type of liquid phase reaction), there is an increased likelihood of being unable to control the temperature inside the reactor (for example, being unable to control the temperature inside the reactor within the preferable range of 0 to 200 ⁰ C). [0044]

Although there are no particular limitations on the "solvent that is inert with respect to the hydrogenation reaction", from the viewpoint of being less susceptible to hydrogenation reactions, an organic solvent not having any ethylenic carbon double bonds (C=C bonds) is preferable.

As shown in Fig. 2, a portion of the n-propyl acetate-containing liquid (hydrogenation reaction liquid 19) formed by the hydrogenation reaction in hydrogenation reactor 40 may also be recycled as the organic solvent (hydrogenation reaction circulating liquid 18). In this case, although there is the possibility of the presence of residual ester having C=C bonds, namely allyl acetate, in a portion thereof as a result of not reacting, there are no particular problems therewith provided there is no substantial impairment of control of the hydrogenation reaction of the present invention. [0045]

Specific examples of "solvent that is inert with respect to the hydrogenation reaction" include saturated esters such as ethyl acetate, n-propyl acetate, butyl acetate, isopropyl acetate, n-propyl propionate, ethyl propionate, butyl propionate or isopropyl propionate; hydrocarbons such as cyclohexane, n-hexane or n-heptane; aromatic hydrocarbons such as benzene or toluene; ketones such as acetone or methyl ethyl ketone; halogenated hydrocarbons such as carbon tetrachloride, chloroform, methylene

chloride or methyl chloride; ethers such as diethyl ether or di-n-propyl ether; alcohols such as ethanol, n-propanol, isopropanol, n-butanol or sec-butanol; and, amides such as N-methyl-2-pyrrolidone or N,N-dimethylacetoamide. Among these, saturated esters, hydrocarbons and ketones are preferable from the viewpoint of being less susceptible to hydrogenation reactions and being less likely to cause hydrogenolysis of allyl acetate. [0046]

The hydrogenation reaction of the present invention can be carried out with a gas phase reaction or liquid phase reaction.

An explanation is first provided of the case of a gas phase reaction. Although a fixed bed reaction apparatus, moving bed reaction apparatus or fluidized bed reaction apparatus and the like can be used for the structural form of hydrogenation reactor 40 in the case of a gas phase reaction, a fixed bed reaction apparatus is used most commonly.

In the case of a gas phase reaction, it is preferable to take the following matters into consideration. In general, the heat of reaction accompanying hydrogenation is extremely large. In addition, in the case of a gas phase reaction, the inflow temperature of reactive substances into hydrogenation reactor 40 is set to a temperature equal to or higher than the boiling point thereof. In this case, if the space-time yield is attempted to be increased, the amount of heat generated accompanying hydrogenation increases, and the temperature inside hydrogenation reactor 40 rises beyond the preferable reaction temperature (for example, 200 ⁰ C), thereby resulting in the risk of acceleration of side reactions in the form of hydrogenolysis. In order to counteract this, the amount of heat generation is suppressed by lowering the space-time yield or the temperature is controlled by cooling and the like.

In the case of a liquid phase reaction, however, the inflow temperature of reactive

substances into hydrogenation reactor 40 can be made to be lower than the boiling point thereof, thereby offering the advantage of making it easy to maintain a preferable reaction temperature (for example, 200 ⁰ C or lower).

Next, an explanation is provided of the case of a liquid phase reaction. Specific examples of the structural forms of reaction apparatuses in the case of a liquid phase reaction include fixed bed, fluidized bed and agitated bed types. From the viewpoint of facilitating separation of catalyst and products following the reaction, a fixed bed reaction apparatus is the most preferable. [0047]

Since hydrogen gas is used in the hydrogenation reaction of the present invention, the manner of flow of fluid in a liquid phase reaction using a fixed bed reaction apparatus is in the form of a gas-liquid two-phase flow consisting of a liquid containing the raw materials and a gas containing the hydrogen gas.

The gas-liquid two-phase flow is divided into three types consisting of a gas-liquid countercurrent flow, gas-liquid downward parallel flow and gas-liquid upward parallel flow based on the manner of flow of the raw material gas and liquid. Although any of these can be used in the present invention, a gas-liquid downward parallel flow type is the most preferable from the viewpoint of allowing efficient contact between the hydrogen and catalyst required for the reaction.

In summary of the above, from the viewpoint of increasing the space-time yield while suppressing hydrogenolysis, the most preferable reaction type of hydrogenation reactor 40 is a gas-liquid two-phase flow type of liquid phase reaction, and the manner of flow of the fluid thereof is a gas-liquid downward parallel flow type. [0048]

In the case of carrying out a gas-liquid two-phase flow type of liquid phase reaction as described above, it is preferable to carry out the hydrogenation reaction in the form of an adiabatic liquid phase reaction by using for the reaction liquid thereof a diluted liquid obtained by diluting the allyl acetate with an inert solvent as described above from the viewpoint of suppressing hydrogenolysis as described above. The reason for this is that a device such as for cooling hydrogenation reactor 40 is not required by lowering the concentration of allyl acetate in the reaction liquid. hi the present invention, n-propyl acetate formed by hydrogenation of allyl acetate may also be recycled as an inert solvent. [0049]

There are no particular limitations on hydrogenation reactor 40 used for the hydrogenation reaction of the present invention. In the case of using a gas-liquid downward parallel flow type of reaction form using a fixed bed reaction apparatus, the use of, for example, a reactor provided with a cooling jacket, a multitubular reaction apparatus provided with a cooling jacket, or an adiabatic reaction apparatus is preferable. An adiabatic reaction apparatus is preferable from the viewpoint of the construction cost of hydrogenation reactor 40, conversion rate of allyl acetate and the like. [0050]

There are no particular limitations on the reaction temperature of the hydrogenation reaction provided it is not contrary to the gist of the present invention. Although varying according to the types of raw materials, a suitable reaction temperature in the present invention is preferably 0 to 200 ⁰ C and particularly preferably 40 to 15O ⁰ C. If the reaction temperature is lower than O ⁰ C, there is a tendency for it to be difficult to obtain an adequate reaction rate, while if the temperature exceeds 200 ⁰ C,

hydrogenolysis tends to proceed easily. [0051]

In the case of a gas phase reaction, adequate activity is obtained even if the reaction pressure of the hydrogenation reaction is normal pressure. Consequently, the reaction is preferably carried out at normal pressure. However, if the pressure is to a degree that allows the allyl acetate to vaporize at a temperature of 200°C or lower, the reaction can be accelerated under pressurized conditions as necessary.

On the other hand, in the case of a liquid phase reaction of the gas-liquid two-phase flow, it is preferable to pressurize the reaction from the viewpoint of ensuring an adequate dissolved hydrogen concentration. The manner of flow of the raw material gas and liquid is preferably in the form of a gas-liquid downward parallel flow as previously described from the viewpoint of ensuring an adequate hydrogen concentration within the reactor during the liquid phase reaction of the gas-liquid two-phase flow hi the case of the liquid phase reaction of the gas-liquid two-phase flow, the reaction pressure is preferably within the range of 0.05 to 10 MPaQ and more preferably within the range of 0.3 to 5 MPaG If the reaction pressure is lower than 0.05 MPaQ it tends to be difficult for the hydrogenation reaction to proceed adequately, while on the other hand, if the reaction pressure exceeds 10 MPaQ hydrogenolysis tends to occur easily.

A gas-liquid downward parallel flow type of reaction form as previously described is the most preferable from the viewpoint of ensuring an adequate hydrogen concentration within hydrogenation reactor 40.

Although hydrogenation reaction liquid 19 (n-propyl acetate-containing liquid)

leaving hydrogenation reactor 40 is supplied to ozone treatment equipment 41, as was previously described, a portion of hydrogenation reaction liquid 19 may also be recycled to hydrogenation reactor 40 in the form of hydrogenation reaction circulating liquid 18. [0052]

(Ozone Treatment Step of n-Propyl Acetate-Containing Liquid) In addition to containing n-propyl acetate formed by the hydrogenation reaction, hydrogenation reaction liquid 19 may also contain impurities such as C3 gases, n-propyl ether, propanal, isopropyl acetate, 2-methylbutanal, allyl acetate, 1-propenyl acetate, n-propanal, propyl n-propionate, allyl propionate, acetic acid, propionic acid or water. Among these impurities, allyl acetate is detected in hydrogenation reaction liquid 19 in the case the allyl acetate conversion rate of the hydrogenation reaction has fallen below 100%. In addition, 1-propenyl acetate is detected in hydrogenation reaction liquid 19 in the case hydrogenation of allyl acetate is incomplete or the reaction stops due to isomerization of allyl acetate and hydrogenation does not proceed further. Moreover, 2-methylbutanal is the result of hydrogenation of 2-methylcroton aldehyde contained in a raw material of the hydrogenation reaction in the form of a highly pure allyl acetate mixture. Since these three components have similar boiling points and low specific volatility, it is difficult to separate them from n-propyl acetate by distillation. [0053]

Therefore, the following provides a detailed explanation of a method for decomposing and removing these three components by oxidation by reacting hydrogenation reaction liquid 19 with ozone.

There are no particular limitations on ozone able to be used for the ozone

treatment. There are also no limitations on the manner in which the ozone is generated, and the ozone may be that which has been obtained by any method. An example of a preferable method for obtaining ozone is that which uses an ozone generator (ozonizer) utilizing silent electric discharge. A detailed description of ozone generators is provided in the section on "Ozone Generators" on pp. 162-163 of the "Encyclopedia of Chemistry, Vol. 2, Encyclopedia of Chemistry Editorial Committee ed., Kyoritsu Shuppan Co., Ltd., March 15, 1969, tablet edition, 7th printing". hi the present invention, before treating the n-propyl acetate obtained by hydrogenating allyl acetate with ozone, it is preferable to completely remove hydrogen dissolved in the n-propyl acetate which is a product of the hydrogenation step with an inert gas such as nitrogen or argon. This is done to ensure safety in the case dissolved hydrogen is present. [0054]

There are no particular limitations on the amount of ozone used in the present invention provided it is an amount of a level that allows the aforementioned three components to be removed. Preferably, the molar ratio of the total amount of the three components contained in the n-propyl acetate liquid to the amount of ozone (the total amount of the three components : ozone) is within the range of 1 :0.1 to 1 :5. If the molar ratio of the total of the three components to the amount of ozone is less than 1:0.1, there is the risk of the removal of the three components not proceeding, thereby making this undesirable. In addition, if an amount of ozone is used such that the above molar ratio exceeds 1:5, by-products are formed by decomposition and oxidation of n-propyl acetate and other impurities. Alternatively, use of an excess amount of ozone is also economically undesirable. More preferably, the molar ratio of the total of the three

components to the amount of ozone is 1 :0.5 to 1 :4 and more preferably 1:1 to 1:3. [0055]

There are no particular limitations on the method used to control the amount of ozone introduced, and any known method may be used.

For example, prior to introducing n-propyl acetate containing the three components into the reactor where ozone treatment is carried out, the amount of the three components in the n-propyl acetate is measured and the amount of ozone introduced is controlled so that the ratio of the three components to ozone is able to be maintained based on the measured values.

There are no particular limitations on the reaction temperature of ozone treatment, and the temperature is preferably 10 to 12O ⁰ C. If the temperature is lower than 10 ⁰ C, it becomes difficult to obtain a practical reaction rate, thereby making this undesirable. In addition, if the temperature exceeds 120 ⁰ C, there is the risk of difficulty in controlling the reaction, thereby making this undesirable. The reaction temperature is more preferably 15 to HO ⁰ C and most preferably 20 to 100 ⁰ C. [0056] hi addition, there are also no particular limitations on the residence time in the ozone treatment reactor. The optimum value for residence time varies according to the physical properties of the three components contained in the n-propyl acetate, the ratio between the three components and ozone, the reaction temperature or other conditions and the like. In general, a residence time of 0.1 to 120 minutes is preferable. If the residence time is less than 0.1 minutes, there is the risk of decomposition, oxidation or removal of the three components not being carried out adequately, thereby making this undesirable. In addition, a residence time in excess of 120 minutes is disadvantageous

in terms of productivity and the like, thereby making this undesirable. The residence time is more preferably 0.5 to 15 minutes and most preferably 1 to 10 minutes. [0057]

An inert gas can be added to the ozone treatment reactor for the purpose of facilitating control of the reaction. It is particularly effective to add an inert gas for the purpose of avoiding an explosive concentration range within the reaction system. Although specific examples of inert gases include nitrogen and argon, nitrogen is most preferable in consideration of ease of acquisition and economic feasibility, hi addition, there are no particular limitations on the amount of inert gas added, and the optimum value thereof varies corresponding to the purpose, such as avoiding an explosive concentration range of substances within the reaction system. [0058]

There are no particular limitations on the manner in which ozone treatment is carried out in the present invention. There are no particular limitations on the manner of ozone treatment provided a reaction form is used that enables the aforementioned three components to be decomposed, oxidized or removed by ozone. Specific examples of reaction forms include continuous/batch, liquid phase/gas phase reactions. A continuous, liquid phase reaction is particularly preferable in the present invention.

Furthermore, although the ozone treatment step may be carried out at any stage in the process for producing n-propyl acetate by using as raw material the highly concentrated allyl acetate process liquid of the present invention, since the main contained raw material in the form of allyl acetate is decomposed leading to a decrease in the yield of n-propyl acetate in the case of carrying out ozone treatment upstream from the hydrogenation step, ozone treatment is preferably carried out downstream from

the hydrogenation step. [0059]

(Purification Step of n-Propyl Acetate)

Next, an explanation is provided of the step for purifying highly pure n-propyl acetate product 21 from liquid containing n-propyl acetate.

Ozone treated liquid 20, hi which the aforementioned three components have been decomposed, oxidized and/or removed hi ozone treatment equipment 41, is led to fifth distillation column 42, where fifth distillation column bottom liquid 24, containing large amounts of high boiling point components such as acetic acid and propyl propionate, and fifth distillation column top liquid 25, containing large amounts of low boiling point components such as C3 gas, propanal and water, are respectively drawn off, and highly pure n-propyl acetate product 21 is withdrawn from an intermediate stage of fifth distillation column 42. Highly pure n-propyl acetate product 21 is obtained in this manner. [0060]

As has been described hi detail thus far, according to the process for producing allyl acetate and n-propyl acetate of the present invention, highly pure and colorless allyl acetate and n-propyl acetate can be produced hi combination hi a process for producing allyl alcohol by using propylene, oxygen and acetic acid as raw materials.

EXAMPLES [0061]

Although the following provides a more detailed explanation of the present invention through examples thereof, the present invention is not limited thereto.

(Production of Catalyst for Producing Allyl Acetate)

One liter of a silica spherical support having a particle diameter of 5 mm (sphere diameter: 5 mm, specific surface area: 155 m ² /g, HSV-I ₅ Shanghai Haiyuan Chemical Technology Co., Ltd.) was added to 346 ml of an aqueous solution containing 16.587 g of sodium tetrachloropalladate (Na ₂ PdCl ₄ ) and 2.1194 g of copper chloride dihydrate (CuCl ₂ ^• H ₂ O) and completely immersed in the solution. Next, this was subjected to alkaline treatment for 20 hours at room temperature by adding to 730 ml of an aqueous solution containing 39.112 g of sodium metasilicate nonahydrate (Na ₂ SiO ₃ ^• 9H ₂ O). Subsequently, reduction treatment was carried out by adding hydrazine hydrate. Following reduction, the solution was rinsed with water until chlorine ions were no longer observed. Next, the solution was dried for 4 hours at 110 ⁰ C. Moreover, the dried product was placed hi 328 ml of an aqueous solution containing 60 g of potassium acetate (KOAc) and after completely absorbing all of the solution, drying was again carried out for 20 hours at HO ⁰ C. This method was then repeated to obtain several cubic meters of catalyst for producing allyl acetate.

(Catalyst for Producing Allyl Alcohol)

A strongly acidic cation exchange resin (trade name: Amberlyst 31 Wet, Organo Corp.) was used to hydrolyze allyl acetate. [0062]

(Production of Allyl Acetate and Allyl Alcohol)

Condensable components comprised mainly of acetic acid and water at 23,130 kg/hr, propylene at 36,445 kg/hr, oxygen at 5,846 kg/hr and other inert gas at 29,440 kg/hr were reacted by passing through an allyl acetate production reactor (reactor 31),

packed with the catalyst for producing allyl acetate produced using the method described above, under conditions of a reaction temperature of 16O ⁰ C and reaction pressure of 0.75 MPaG.

At this time, the flow rate of allyl acetate contained in the outlet gas of the allyl acetate production reactor (reactor outlet gas 4) was 13,431 kg/hr. [0063]

The outlet gas of this allyl acetate production reactor was supplied to a gas-liquid separation column (absorption column 32), non-condensable components comprised mainly of propylene, oxygen and carbon dioxide gas were separated from the top of the gas-liquid separation column using first distillation column bottom liquid 9, comprised mainly of acetic acid and water, as an absorbing liquid, and a portion thereof was recirculated to the allyl acetate production reactor with a compressor. On the other hand, absorption column bottom liquid 5, containing condensable components in the form of acetic acid, water, allyl acetate and other components, was obtained from the bottom of the gas-liquid separation column.

Moreover, allyl acetate was hydrolyzed by passing a mixture of the absorption column bottom liquid 5 and extraction column top liquid 10 (hydrolysis reactor feed liquid 6) through an allyl alcohol production reactor (hydrolysis reactor 33) packed with a catalyst for producing allyl alcohol in the form of an ion exchange resin under conditions of a reaction temperature of 85 ⁰ C and reaction pressure of 0.5 MPaG At this time, the flow rate of allyl alcohol in the outlet liquid of the allyl alcohol production reactor (hydrolysis reactor reaction liquid 7) was 8,392 kg/hr. [0064]

Next, a distillation procedure was carried out in first distillation column 34 for the

purpose of separating acetic acid from the outlet liquid of the allyl alcohol production reactor comprised mainly of allyl alcohol, allyl acetate, acetic acid and water. A portion of the aqueous acetic acid solution obtained from the bottom of the column (first distillation column bottom liquid 9) was recirculated to the allyl acetate production reactor (reactor 31), while the remainder was recirculated in the form of absorbing liquid of the gas-liquid separation column (absorption column 32) for allyl acetate production reactor outlet gas.

Top liquid of first distillation column 34 was separated into an oily layer 8 rich in allyl acetate and an aqueous layer 27 by decantation. The flow rates of the main components of oily layer 8 supplied to extraction column 35 were as indicated below: Allyl alcohol: 7,851 kg/hr Allyl acetate: 11,841 kg/hr Water: 4,085 kg/hr. [0065]

Allyl alcohol in oily layer 8 was extracted in extraction column 35 by using third distillation column bottom liquid 13 comprised mainly of water as extracting water. The oily layer comprised mainly of allyl acetate obtained from the top of the column was reused by circulating to the allyl alcohol production reactor.

Extraction column bottom liquid 11 of extraction column 35 was supplied to second distillation column 36, contained low boiling point components were separated and removed from the top of the column, and a liquid comprised mainly of allyl alcohol and water (second distillation column bottom liquid 12) was obtained from the bottom of the column.

In third distillation column 37, second distillation column bottom liquid 12 was

distilled to obtain 70% by weight of allyl alcohol (allyl alcohol product 14) from the top of the column, hi addition, a portion of third distillation column bottom liquid 13 was recirculated to extraction column 35 and used as extracting water, while the remainder was used by circulating to the allyl alcohol production reactor. [0066]

Analyses in the examples were carried out according to the methods described below.

Analyses of each composition were carried out by gas chromatography and a Karl Fischer moisture analyzer. In addition, liquid hues (Hazen values) were determined in accordance with the method described in JIS K-0071. Karl Fischer Moisture Analyzer

Instrument: MKC-210 (Kyoto Electronics Mfg. Co., Ltd.) Hazen Values

Measurement method: 1.25 g of potassium hexachloroplatinate (TV) (K ₂ PtCl ₆ ) and 1.00 g of cobalt chloride (CoCl ₂ ^• 6H ₂ O) were placed in a beaker, dissolved with 100 ml of hydrochloric acid, and transferred to a 1000 ml volumetric flask and brought to a final volume of 1000 ml with distilled water. This solution was used as Hazen 500 standard colorimetric bulk solution. 10 ml of this Hazen 500 standard colorimetric bulk solution were taken and diluted with 40 ml of pure water to prepare a Hazen 100 standard colorimetric solution. Standard colorimetric solutions were also prepared in the same manner in increments of 10 over the range of Hazen 90 to Hazen 10 and for Hazen values of 15 and 5. The hues of these prepared standard colorimetric solution and measurement samples were visually compared, and the Hazen value of the standard colorimetric solution that was closest to the hue of the measurement sample was taken

to be the Hazen value of that measurement sample.

Gas Chromatography Analysis Conditions

Instrument: GC-17A (Shimadzu Corp.)

Detector: Hydrogen flame ionization detector

Measurement method: Internal standard method (internal standard substance: 1,4-dioxane)

Injection temperature: 200°C

Heating conditions: Held for 5 minutes at 4O ⁰ C followed by heating at 5°C/minute and holding for 18 minutes at 200 ⁰ C

Column used: TC-WAX (GL Science Inc.), inner diameter: 0.25 mm, length: 30 m [0067]

[Example 1]

13 liters of extraction column top liquid 10 as previously described were taken and analyzed in detail. The composition thereof was shown in Table 1. [0068]

[Table 1]

[0069]

Highly pure allyl acetate was obtained by carrying out a distillation procedure on the sample liquid using an Oldershaw distillation column (equivalent to fourth distillation column 38). The distillation procedure was carried out under the conditions indicated below.

Oldershaw type: Sieve tray

Oldershaw inner diameter: 34 mm

Tray opening ratio: 7%

Plate interval: 30 mm

No. of actual plates: 40

Plates supplied with liquid: 20th (no. of plates from top of column, to be used similarly hereinafter)

Highly pure allyl acetate distillate plates: 10

Liquid supply volume: 13 L

Highly pure allyl acetate distillate volume: 5.2 L

Column top extraction volume: 5.2 L

Column bottom extraction volume: 2.6 L

Reflux ratio: 8

Column top condenser refrigerant temperature: 10 ⁰ C

Column top pressure: 101.3 kPa (absolute pressure) lst-plate temperature: 99 to 100 ⁰ C

20th-plate temperature: 103 to 104 ⁰ C

40th-plate temperature: 111 to 114 ⁰ C

As a result of analyzing highly pure allyl acetate obtained by withdrawing after 10th-plate using the distillation procedure described above, the composition thereof was shown in Table 2.

[0070]

[Table 2]

[0071]

Next, the highly pure allyl acetate liquid obtained according to the distillation

procedure described above was supplied to a decoloration apparatus using fluorescent light irradiation (equivalent to photoirradiation equipment 39). The decoloration step was carried out by allowing the highly pure allyl acetate to flow upward through vertically installed glass tube and irradiating with fluorescent light from the both sides thereof.

Fluorescent lamp: FHT-41085N-PN9 (Toshiba Lighting & Technology Corp.)

Fluorescent lamp output: 35 watts x 2 lamps

Fluorescent lamp length: 1200 mm

Glass tube inner diameter: 20 mm

Highly pure allyl acetate liquid supply rate: 100 mL/hr (total supply volume: 5.0

L)

Liquid residence time in area irradiated by fluorescent lamp: 3.8 hrs

The Hazen value of liquid obtained according to the procedure described above was 5 or less. [0072]

Hydrogenation was carried out on the decolored highly pure allyl acetate as described above using an autoclave (equivalent to hydrogenation reactor 40) to obtain n-propyl acetate. The hydrogenation reaction was carried out under the conditions indicated below.

Apparatus: 10 L autoclave

Highly pure allyl acetate charging volume: 4.9 L

Catalyst: HD-403, N.E. Chemstat Inc. (Lot No. 266-04H040, Pd(0.3 wt%)/Al ₂ θ ₃ , spherical, diameter: 2 mm)

Amount of catalyst: 60 g

Reaction temperature: 75 ⁰ C

Reaction pressure (hydrogen pressure): 0.58 to 0.68 MPaG

The reaction pressure was initially set to 0.58 MPaQ and then gradually increased to a final pressure of 0.68 MPaG by injecting hydrogen gas because the concentration of substrate in the form of allyl acetate is lowered and the reaction rate decreases as the hydrogenation progressed. As a result of analyzing the n-propyl acetate obtained according to the above procedure, the composition thereof was as shown in Table 3. [0073]

[Table 3]

[0074]

Highly pure n-propyl acetate was obtained from the hydrogenated liquid described above by a distillation procedure using an Oldershaw distillation column (equivalent to fifth distillation column 42). The distillation procedure was carried out under the conditions indicated below.

Oldershaw type: Sieve tray

Oldershaw inner diameter: 34 mm

Tray opening ratio: 7%

Plate interval: 30 mm

No. of actual plates: 40

Plates supplied with liquid: 20th (no. of plates from top of column, to be used similarly hereinafter)

Highly pure n-propyl acetate distillate plates: 10

Liquid supply volume: 4.3 L

Highly pure n-propyl acetate distillate volume: 3.3 L

Column top extraction volume: 0.5 L

Column bottom extraction volume: 0.5 L

Reflux ratio: 40

Column top condenser refrigerant temperature: 1O ⁰ C

Column top pressure: 101.3 kPa (absolute pressure) lst-plate temperature: 97 to 99 ⁰ C

20th-plate temperature: 101 ⁰ C

40th-plate temperature: 108 to 109 ⁰ C

As a result of analyzing highly pure n-propyl acetate obtained by withdrawing after 10th-plate using the distillation procedure described above, the composition thereof was shown in Table 4. [0075]

[Table 4]

[0076]

[Example 2]

The same procedure as Example 1 was repeated through the hydrogenation step to obtain a composition as shown in Table 3 followed by carrying out ozone treatment on the liquid according to the method indicated below.

Ozone generator: POX-10/Oxygen (Fuji Electric Co., Ltd.)

Ozone treatment method: 1.0 liter of the composition shown in Table 3 was charged into a 1 liter graduated cylinder and ozone-containing gas generated from the ozone generator was diffused from the lower portion of the graduated cylinder to allow the gas-liquid contact for 2 hours. Furthermore, the above treatment was carried out at normal temperature and normal pressure.

Ozone generator oxygen feed rate: 2.0 L/min

Ozone generation rate: 2.0 g/hr

The above treatment was repeated five times to treat a total of 4.5 liters of the composition shown in Table 3 with ozone. The composition of the resulting liquid was shown in Table 5.

[0077]

[Table 5]

[0078]

Highly pure n-propyl acetate was obtained from the ozone-treated liquid by a distillation procedure using an Oldershaw distillation column. The distillation procedure was carried out under the conditions indicated below.

Oldershaw type: Sieve tray

Oldershaw inner diameter: 34 mm

Tray opening ratio: 7%

Plate interval: 30 mm

No. of actual plates: 40

Plates supplied with liquid: 20th (no. of plates from top of column, to be used similarly hereinafter)

Highly pure n-propyl acetate distillate plates: 10

Liquid supply volume: 4.3 L

Highly pure n-propyl acetate distillate volume: 3.3 L

Column top extraction volume: 0.5 L

Column bottom extraction volume: 0.5 L

Reflux ratio: 40

Column top condenser refrigerant temperature: 1O ⁰ C

Column top pressure: 101.3 kPa (absolute pressure) lst-plate temperature: 97 to 99°C

20th-plate temperature: 101°C

40th-plate temperature: 108 to 109 ⁰ C

As a result of analyzing highly pure n-propyl acetate obtained by withdrawing after 10th-plate using the distillation procedure described above, the composition thereof was shown in Table 6.

[0079]

[Table 6]

[0080]

[Comparative Example 1]

The results of analyzing the final n-propyl acetate in the case of not carrying out fluorescent lamp irradiation and ozone treatment when obtaining highly pure n-propyl acetate according to the methods described in Examples 1 and 2 were shown in Table 7. [0081]

[Table 7]

[0082]

[Example 3]

Approximately 4 liters of the composition of Table 2 described in Example 1 (fourth distillation column distillate 16) were irradiated at room temperature for 25.25 hours at specific wavelengths at wavelength increments of 30 nm between 305 to 515 run at 4 to 7 mW using the specific wavelength irradiation apparatus described below, followed by measuring the optical absorbance of the irradiatediiquid at 350 to 500 nm using the optical absorbance measuring apparatus described below. The results are shown in Fig. 3.

Specific wavelength irradiation apparatus: CRM-FD multi- wavelength irradiation spectrometer (JASCO Corp.; apparatus which is equipped with 300 W xenon lamp, focusing parabolic mirror and diffraction grating spectrometer, and radiates comparatively intense monochromatic light. Wavelength accuracy: about 12 nm).

Optical absorbance measuring apparatus: MPS-2450 spectrophotometer (Shimadzu Corp., double-beam self-recording spectrophotometer, wavelength accuracy: about 1 nm, measurement performed by correcting the baseline without inserting a quartz measurement cell (path length: 1 cm) in the sample side or reference side followed by placing an empty quartz cell in the reference side).

[0083]

As shown in Fig. 3, with respect to those samples irradiated at a wavelength of 395 to 425 nm, optical absorbance over the wavelength range of 400 to 480 nm, at which complementary colors in the form of yellow-green or yellow are observed, was determined to decrease considerable as compared with samples prior to irradiation.

On the basis of these results, a specific wavelength of 400 to 450 nm was determined to be advantageous for decoloring the composition.