KR100231625B1 - Process for producing phenol and methyl ethyl ketone - Google Patents

Abstract

From (A) sec-butylbenzene substantially free of ethyl hydroperoxide, carboxylic acid and phenol, (B) sec-butylbenzene substantially free of styrene and (C) sec-butylbenzene substantially free of methylbenzyl alcohol Any one material of choice is oxidized to yield sec-butylbenzene hydroperoxide, which is then decomposed to yield phenol and methyl ethyl ketone.

Description

Method for preparing phenol and methyl ethyl ketone

The present invention relates to a process for preparing phenol and methyl ethyl ketone. More specifically, the present invention relates to a process for preparing phenol and methyl ethyl ketone using sec-butylbenzene as starting material.

It is already known that phenol and methyl ethyl ketone are prepared by oxidizing sec-butylbenzene to sec-butylbenzene hydroperoxide and decomposing this sec-butylbenzene hydroperoxide (Japanese Patent Laid-Open No. 48-80524). ). However, in this conventional method, in addition to the liquid containing phenyl and methyl ethyl ketone, a liquid containing unreacted sec-butylbenzene is recovered. Therefore, in view of the use efficiency of the raw materials, it is preferable to reuse the unreacted sec-butylbenzene by recycling the liquid containing the unreacted sec-butylbenzene to the oxidation step. However, the conventional method has the following problems. The liquid containing unreacted sec-butylbenzene contains impurities that inhibit the oxidation reaction. Recycling the liquid containing such unreacted sec-butylbenzene to the oxidation step without removing impurities undesirably accumulates impurities in the oxidation reaction system, and the accumulation of impurities very adversely reduces the oxidation reaction rate.

One example of such impurities is ethyl hydroperoxide, which is formed as a byproduct upon oxidation. It accumulates in the reaction system and reduces the rate of oxidation reactions. Moreover, the accumulation of ethyl hydroperoxide in the system is undesirable in terms of stability due to the explosiveness of ethyl hydroperoxide. Concerning the elimination of by-products formed during oxidation, a method of inhibiting the undesirable formation of carboxylic acid by-products by adding alkali to the oxidation reaction system during the oxidation of cumene to cumene hydroxide peroxide is known. Patent Publication No. 63-42619). However, applying this method to oxidation systems for oxidizing sec-butylbenzene to sec-butylbenzene hydroperoxide reduces the selectivity of the oxidation reaction.

Moreover, when the recovered liquid containing unreacted sec-butylbenzene is recycled to the sec-butylbenzene oxidation step, styrene inevitably climbs. Styrene is formed in the decomposition step, which can hardly be removed using a multi-stage distillation column. These cause a problem of decreasing the unit hourly yield from sec-butylbenzene to sec-butylbenzene hydroperoxide (Japanese Patent Laid-Open No. 48-80524).

Moreover, the recovered liquid containing unreacted sec-butylbenzene contains an oxide inhibiting impurity such as methyl benzyl alcohol even after removing the aforementioned antioxidant.

Recognizing this situation, the object of the present invention is to sec from sec-butylbenzene, which prevents the accumulation of undesirable side products in the production system, reuses and efficiently recycles unreacted sec-butylbenzene, and maintains high levels of oxidation. Provided is a process for preparing phenol and methyl ethyl ketone via -butylbenzene hydroperoxide.

The present inventors have conducted extensive research to solve the above-mentioned problems and completed the present invention as a result.

According to the invention there is provided a process for the preparation of phenol and methyl ethyl ketone, characterized by the following steps:

(I) sec-butylbenzene substantially free of (A) ethyl hydroperoxide, carboxylic acid and phenol, (B) sec-butylbenzene substantially free of styrene and (C) sec- substantially free of methyl benzyl alcohol Oxidizing one material selected from the group consisting of butylbenzene to obtain sec-butylbenzene hydroperoxide, and (II) decomposing sec-butylbenzene hydroperoxide to obtain phenol and methyl ethyl ketone.

The process of the present invention is first described below from the case where (A) sec-butylbenzene which is substantially free of ethyl hydroperoxide, carboxylic acid and phenol is selected as starting material. That is, a process for producing phenol and methyl ethyl ketone, wherein step (I) comprises the step (A) selecting sec-butylbenzene substantially free of ethyl hydroperoxide, carboxylic acid and phenol as starting material.

This method features the following steps:

Oxidation step (A1): oxidizing sec-butylbenzene substantially free of ethyl hydroperoxide, carboxylic acid and phenol to obtain a reaction liquid and exhaust gas containing sec-butylbenzene hydroperoxide as a main product:

Condensation step (A2): cooling the exhaust gas obtained in the oxidation step (A1) to obtain a condensate containing sec-butylbenzene, ethyl hydroperoxide, carboxylic acid and phenol:

Concentration step (A3): The reaction solution obtained in the oxidation step (A1) was distilled and concentrated to give a base liquid containing sec-butylbenzene hydroperoxide as a main component at the bottom of the column, sec-butylbenzene, ethyl hydroperox Obtaining a distillate containing seed, carboxylic acid and phenol on the column:

Alkali washing step (A4): The condensate obtained in the condensation step (A2) and the distillate obtained in the concentration step (A3) are washed with an aqueous alkali solution, which is separated into an oil layer and an aqueous layer, and the oil layer is subjected to an oxidation step (A1). The amount of alkali in the aqueous alkali solution is in the range of 1 to 10 moles per one mole of the total amount of ethyl hydroperoxide, carboxylic acid and phenol present in the total condensate and distillate, and is present in the total condensate and distillate. To a range of 10 to 100 moles per mole of carboxylic acid and phenol as a whole:

Decomposition step (A5): Decomposition of the base liquid containing sec-butylbenzene hydroperoxide obtained in the concentration step (A3) as a main component to obtain phenol and methyl ethyl ketone.

As starting material sec-butylbenzene (A) preferably contains 0.01 to 0.5% by weight ethyl hydroperoxide, 0.01% by weight or less of carboxylic acid and 0.001% or less of phenol.

The oxidation step (A1) is a step of oxidizing sec-butylbenzene to obtain an oxidation reaction liquid containing sec-butylbenzene hydroperoxide as a main product. This step is performed by contacting sec-butylbenzene liquid with oxygen-containing gas at a temperature of 90 to 150 ° C. and a pressure of ^{1 to 10} kg / cm ² G to convert sec-butylbenzene to sec-butylbenzene hydroperoxide. By phone.

Condensation step (A2) is a step of cooling the oxidation exhaust gas discharged from the oxidation step (A1) to obtain a condensate containing sec-butylbenzene, ethyl hydroperoxide, carboxylic acid and phenol. This step can be performed using a conventional chiller.

In the concentration step (A3), the oxidation reaction solution was distilled and concentrated to obtain a base liquid containing sec-butylbenzene hydroperoxide as a main component at the bottom of the column, and sec-butylbenzene, ethyl hydroperoxide, carboxylic acid and phenol. It is a step of obtaining a distillate containing on the column. The distillate contains carboxylic acid and a small amount of phenol in addition to sec-butylbenzene and ethyl hydroperoxide.

The distillation conditions in the concentration step (A3) ie, the base liquid containing sec-butylbenzene hydroperoxide as a main component can be separated from the distillate containing sec-butylbenzene, ethyl hydroperoxide, carboxylic acid and phenol. Choose to be. For example, distillation is performed at a column bottom temperature of 50-150 ° C. and a column overhead pressure of 1-200 torr.

In the oxidation step (A1), by-products such as ethyl hydroperoxide carboxylic acid and phenol are also formed with the desired sec-butylbenzene hydroperoxide. Some of these by-products are distilled out of the oxidation vessel where the exhaust gas is oxidized with unreacted sec-butylbenzene and recovered as condensate in condensation step (A2). Moreover, the distillate obtained in the concentration step (A3) contains by-products such as ethylhydroperoxide, carboxylic acid and phenol, in addition to SEC-butylbenzene. The sec-butylbenzene contained in these condensates and distillates must be recycled to the oxidation step (A1) and reused as starting material for oxidation. However, if the condensate and distillate containing by-products such as ethyl hydroperoxide, carboxylic acid and phenol are recycled to the oxidation step without removing the by-products, the by-products accumulate in the system and the It reduces the reaction rate, lowers the volumetric efficiency of the reactor, and causes problems in stability such as explosion. The present invention can overcome these disadvantages. We first discovered that byproducts such as ethyl hydroperoxide, carboxylic acid and phenol that cause this difficulty can be removed at once in the alkaline washing step described below. The alkali washing step (A4) washes the condensate obtained in the condensation step (A2) and the distillate obtained in the concentration step (A3) with an aqueous alkali solution, which is separated into an oil layer and an aqueous layer, and the oil layer is subjected to an oxidation step (A1). The amount of alkali in the aqueous alkali solution ranges from 1 to 10 moles per mole of the total amount of ethyl hydroperoxide, carboxylic acid and phenol present in the total condensate and distillate, and is present throughout the condensate and distillate. It is a step to make the range of 10 to 100 of the total carboxylic acid and phenol. The content of each by-product of the alkali liquid to be washed is changed depending on the operating conditions of the previous step. These are usually 0.1 to 5% by weight ethyl hydroperoxide, 0.01 to 1% by weight carboxylic acid and 0.001 to 0.1% by weight phenol. The conditions for alkali washing are as follows.

Alkali used for alkali washing is usually an aqueous solution of alkali metal hydroxide or alkali metal carbonate. Particular preference is given to aqueous sodium hydroxide solution. The amount of alkali used is 1 to 10 moles, preferably 2 to 7 moles per mole of ethyl hydroperoxide, carboxylic acid and phenol total, and 10 to 100 moles per mole of carboxylic acid and phenol total, preferably 10 to 60 moles. If the amount of alkali is too small, the effect of removing by-products tends to be insufficient. Conversely, if this amount is too high, it tends to cause a loss of alkali. The alkali concentration of the aqueous alkali solution used is generally 1 to 30% by weight, preferably 3 to 15% by weight. If this concentration is too low, the amount of waste water tends to increase. On the contrary, if this concentration is too high, the separation of the oil and water layers tends to be poor after washing. The temperature of the alkali washing step (A4) is generally from room temperature (about 20 ° C.) to 80 ° C. If this temperature is too low, it sometimes becomes poor to separate into two layers. If this temperature is too high, hydroperoxide tends to decompose. Alkali washing should be carried out in practice such that, for example, the liquid to be washed using a vessel equipped with a stirrer, a line mixer, a pipe mixer, etc., comes into full contact with the aqueous alkali solution and then separated into an oil layer and an aqueous layer. In the alkaline washing step (A4), undesired by-products can be separated very efficiently from the oil layer, and the concentration of by-products in the oil layer is generally from 0.01 to 0.5% by weight for ethyl hydroperoxide and 0.01% for carboxylic acid. Up to% and up to 0.001% by weight relative to phenol.

The desired final products, phenol and methyl ethyl ketone, were obtained from the column bottom in the concentration step, and the base liquid containing sec-butylbenzene hydroperoxide as a main component was decomposed with an acidic catalyst to convert the hydroperoxide into phenol and methyl ethyl ketone. After the preparation, the product can be prepared by freeing and purifying.

As one preferred embodiment of the present invention, the hydrogenation step (A6) and distillation step (A7) described below may be provided after the alkali washing step (A4).

The hydrogenation step (A6) is a step of converting ethyl hydroperoxide into ethanol by hydrogenation of the aqueous layer obtained in the alkali washing step (A4) immediately or after neutralization. Hydrogenation conditions are as follows, for example. The catalyst can be selected from conventional hydrogenation catalysts such as palladium, platinum, ruthenium and rhodium. These catalysts can also be used after being supported on carriers such as activated carbon, silica, alumina, silica-alumina and activated clay. The reaction temperature is usually room temperature (about 20 ° C) to 150 ° C, preferably 40 ° C to 100 ° C. If the temperature is too high, the reaction tends to be difficult to control. Conversely, if the temperature is too low, the reaction tends to proceed too slowly. The pressure is usually 1 to 30 kg / cm ² G, preferably 1 to 15 kg / cm ² G. If the pressure is too high, the reaction tends to be difficult to control. If the pressure is too low, the reaction tends to proceed too slowly. The amount of hydrogen supplied may be 1 mole per mole of ethyl hydroperoxide. However, excess hydrogen can be added to increase the hydrogenation rate. In this case, the amount of hydrogen supplied is usually 1-10 moles, preferably 1-5 moles per mole of ethyl hydroperoxide. The excess hydrogen can be recycled and reused. If the amount of hydrogen supplied is too small, the progress of hydrogenation tends to be insufficient. If the amount is too large, the amount of recycled hydrogen tends to be excessively high, which is undesirable. The reaction mode of hydrogenation is not particularly limited. Hydrogenation can be carried out in any form of fixed bed, fluidized bed and suspension. Thus a hydrogenation reaction solution containing ethanol, carboxylic acid and phenol is obtained.

The distillation step (A7) is a step of recovering ethane at the top of the column by distilling the hydrogenation reaction solution obtained in the hydrogenation step (A6). Distillation conditions are selected to obtain a distillate containing ethanol as a main component and a base solution containing carboxylic acids and phenols. Examples of such conditions include a column bottom temperature of 50 to 150 ° C. and a column top pressure of 0.2 to 5 kg / cm ² G.

Ethanol can be recovered by the hydrogenation step (A6) and distillation step (A7). The recovered ethanol can be effectively used as a valuable compound for various purposes. On the other hand, the carboxylic acid and a small amount of phenol are recovered as the column base liquid, and are processed and then disposed of in a wastewater treatment step. In addition, part of the drainage can be recycled to the alkaline washing step A4 to reduce the fragrance of the waste water and to prevent the loss of excess alkali.

In another preferred embodiment of the invention, the pyrolysis step (A8) described below is provided after the alkali washing step (A4). The pyrolysis step (A8) is a step of pyrolyzing ethyl hydroperoxide by immediately pyrolyzing the water layer obtained in the alkali washing step (A4) immediately or after neutralization. Pyrolysis is carried out in a temperature range of 80 to 200 ° C, preferably 100 to 160 ° C. If the reaction temperature is too high, the control of the reaction tends to be difficult. If the reaction temperature is too low, the reaction tends to proceed too slowly. In the reaction, the pressure should be in the range in which ethyl hydroperoxide can be maintained in the liquid phase (ie, aqueous solution). By pyrolysis, ethyl hydroperoxide is broken down into ethanol, acetaldehyde and acetic acid. In this way, microorganisms in activated sludges are destroyed and dangerous hydroperoxides are removed during wastewater treatment which reduces the activity of sludges (Comparative: Japanese Patent Publication No. 63-42619). Another preferred embodiment of the present invention includes using heat recovered for steam power generation or other suitable purposes by recovering the heat of decomposition generated during pyrolysis with a conventional heat exchanger or the like.

Next, the method of the present invention will be described in the case where (B) sec-butylbenzene substantially free of styrene is selected as starting material. That is, a process for producing phenol and methyl ethyl ketone, wherein step (I) comprises selecting (B) sec-butylbenzene substantially free of styrene as starting material.

The present invention is characterized by the following steps: oxidation step (B1): oxidizing sec-butylbenzene substantially free of styrene to obtain a reaction liquid containing sec-butylbenzene hydroperoxide as a main product: concentration step (B2): The reaction solution obtained in the oxidation step (B1) was distilled and concentrated to obtain a base liquid containing sec-butylbenzene hydroperoxide as a main component at the bottom of the column, and containing sec-butylbenzene as a main component. A distillate is obtained at the top of the column, and the distillate is recycled to the oxidation step (B1): decomposition step (B3): concentration step (B2) to decompose sec-butylbenzene hydroperoxide into phenol and methyl ethyl ketone Step of contacting the base liquid obtained in the step) with an acidic catalyst to obtain a decomposition solution: Neutralization step (B4): Neutralization of the decomposition solution obtained in the decomposition step (B3) with an aqueous alkali solution, this is the oil layer and water Separating and recycling part of the aqueous layer to the present step (B4) a; And purification step (B5): distilling the oil layer obtained in the neutralization step (B4) to separate into fractions containing phenol as a main component, fractions containing methyl ethyl ketone as a main component, and fractions containing sec-butylbenzene as a main component. and recycling the fraction containing sec-butylbenzene as a main component to the oxidation step (B1). As starting material sec-butylbenzene (B) preferably contains up to 0.1% by weight of styrene.

The oxidation step (B1) is a step of oxidizing sec-butylbenzene to obtain an oxidation reaction liquid containing sec-butylbenzene hydroperoxide as a main product. This step is performed by contacting sec-butylbenzene liquid with coral-containing gas at a temperature of 90 to 150 ° C. and a pressure of ^{1 to 10} kg / cm ² G, thereby converting sec-butylbenzene to sec-butylbenzene hydroperoxide. By phone.

In the concentration step (B2), the oxidation reaction solution is distilled and concentrated to obtain a base liquid containing sec-butylbenzene hydroxide peroxide as a main component at the bottom of the column, and a distillate containing sec-butylbenzene as a main component at the top of the column. To obtain.

The distillation conditions in the concentration step (B2) are selected such that the base liquid containing sec-butylbenzene hydroperoxide as a main component can be separated from the distillate containing sec-butylbenzene as a main component. For example, distillation is performed at a column bottom temperature of 50 to 150 ° C. and a column top pressure of 1 to 200 torr.

The decomposition step (B3) is a step of contacting the base liquid of the concentration step (B2) with an acidic catalyst to decompose it into sec-butylbenzene hydroperoxide dephenol and methyl ethyl ketone. Acidic catalysts used include sulfuric acid, sulfuric anhydride, perchloric acid and phosphoric acid.

Acidic catalysts are usually used in amounts of 0.01 to 1% by weight. The decomposition temperature is usually in the range of 50 to 100 ° C.

The neutralization step (B4) is a step of neutralizing the decomposition liquid obtained in the decomposition step (B3) with an aqueous alkali solution, separating it into an oil layer and an aqueous layer, and recycling a part of the aqueous layer to the inlet of the neutralization step (B4) again. Alkali used for neutralization includes hydroxides, carbonates and bicarbonates of sodium, potassium and lithium. Alkali is usually used in amounts sufficient to maintain the pH of the aqueous layer at 4-11, preferably 4-9. Preferably, the temperature is from room temperature (about 20 ° C.) to 90 ° C., and the increase ratio of the oil layer to the aqueous layer is 0.5 to 5. The neutralization step (B4) is carried out so that the liquid layer to be neutralized can be brought into complete contact with the aqueous alkali solution and then separated into an oil layer and an aqueous layer. This step is carried out using a vessel equipped with, for example, a stirrer, a line mixer, a pipe mixer, or the like. In the neutralization step B4, a portion of the water layer that was used in the neutralization step B4 can be recycled and reused to reduce the amount of wastewater. Recycling the aqueous layer consequently increases the salt concentration in the thickening step (B4); Therefore, it is preferable to keep the salt concentration at 1 to 30% by weight normally. The oil layer obtained in the neutralization step (B4) is triturated in the subsequent purification step. On the other hand, part of the aqueous layer is discarded and the rest is recycled to the neutralization step (B4).

In the purification step (B5), the oil layer obtained in the neutralization step (B4) is distilled, and the oil layer contains a fraction containing phenol as a main component, a fractionator containing methyl ethyl ketone as a main component, and a fraction containing sec-butylbenzene as a main component. And the fraction containing sec-butylbenzene as a main component is recycled to the oxidation step (B1). This step is usually carried out using a plurality of distillation columns.

One characteristic of the above process is that the fraction containing sec-butylbenzene as the main component recycled from the purification step (B5) to the oxidation step (B1) is a substantially styrene free fraction. Preferred methods of removing styrene from the fraction to be recycled are described in detail below.

One preferred method is characterized by providing a hydrogenation step (B6) and a separation step (B7).

The hydrogenation step (B6) is a step of hydrogenating a fraction containing sec-butylbenzene as a main component obtained in the purification step (B5) to convert styrene contained in the fraction into alkyl benzene. Hydrogenation conditions are as follows, for example. The catalyst to be used can be selected from conventional hydrogenation catalysts such as palladium, platinum, ruthenium and rhodium. These catalysts can also be used after being supported on carriers such as activated carbon, silica, alumina, silica-alumina and activated clay. The reaction temperature is usually room temperature (about 20 ° C) to 140 ° C, preferably 50 to 100 ° C. If the temperature is too high, the reaction tends to be difficult to control. Conversely, if the temperature is too low, the reaction tends to proceed too slowly. The pressure is usually 5-30 kg / cm ² G, preferably 10-20 kg / cm ² G. If the pressure is too high, the reaction tends to be difficult to control. If the pressure is too low, the reaction tends to proceed too slowly. The amount of hydrogen supplied may be 1 mole per mole of styrene, but excess hydrogen may be added to ensure sufficient hydrogenation. In this case, the amount of hydrogen supplied is usually 1-10 moles, preferably 4-7 moles per mole of styrene. The excess hydrogen added can be recycled and reused. If the amount of hydrogen supplied is too small, the progress of hydrogenation tends to be insufficient. Conversely, if the amount is too large, the amount of recycled hydrogen tends to be excessively high, which is undesirable. The reaction mode of hydrogenation is not particularly limited. Hydrogenation can be carried out in any form of fixed bed, fluidized bed and suspension.

Thus, styrene is converted to alkylbenzenes. This step converts α, β dimethylstyrene and α-ethylstyrene to sec-butylbenzene, the starting material of the oxidation step (B1). sec-butylbenzene is recovered and reused via subsequent distillation steps.

Separation step (B7) is a step of distilling the hydrogenation reaction solution obtained in hydrogenation step (B6) to recover sec-butylbenzene, and recycling sec-butylbenzene to oxidation step (B1). Distillation conditions are selected so that a distillate containing sec-butylbenzene as a main component can be obtained. For example, distillation is performed at a column bottom temperature of 50-150 ° C. and column top pressure of 1-200 Torr.

According to the above-mentioned method comprising a hydrogenation step (B6) and a separation step (B7), as an starting material for oxidation, the oxidation, without lowering the unit hourly yield of sec-butylbenzene hydroperoxide from sec-butylbenzene Unreacted sec-butylbenzene can be effectively reused. Furthermore, α, β-dimethylstyrene and α-ethylstyrene, which are undesirable compounds for oxidation, can be converted into sec-butylbenzel and can be effectively used as starting materials for oxidation. Thus, this method is particularly advantageous from an industrial point of view.

This method allows the concentration of styrene contained in sec-butylbenzene recycled in the purification step to below 0.1% by weight, while the concentration of styrene is usually about 10% by weight in the absence of the hydrogenation step.

Next, the method of the present invention will be described when (C) sec-butylbenzene substantially free of methylbenzyl alcohol is selected as starting material. That is, a process for producing phenol and methyl ethyl ketone comprising the step (I) of selecting (C) sec-butylbenzene substantially free of methyl benzyl alcohol as starting material.

The invention features the following steps:

Oxidation step (C1): oxidizing sec-butylbenzene substantially free of methylbenzyl alcohol to obtain a reaction solution containing sec-butylbenzene hydroperoxy as a main product:

Concentration step (C2): The reaction solution obtained in the oxidation step (C1) was distilled and concentrated to obtain a base liquid containing sec-butylbenzene hydroperoxide as a main component at the bottom of the column, and containing sec-butylbenzene as a main component. And obtaining a distillate substantially free of methylbenzyl alcohol at the top of the column, and recycling this distillate to the oxidation step (C1):

Decomposition step (C3): contacting the base liquid obtained in concentration step (C2) with an acidic catalyst to decompose sec-butylbenzene hydroperoxide into phenol and methyl ethyl ketone to obtain a decomposition solution:

Neutralization step (C4): neutralizing the decomposition solution obtained in the decomposition step (C3) with an aqueous alkali solution, separating it into an oil layer and an aqueous layer, and recycling a part of the aqueous layer to this step (C4): and

Purification step (C5): The oil layer obtained in the neutralization step (C4) is distilled to distill the fraction containing phenol as a main component, the fraction containing methyl ethyl ketone as a main component, and the sec-butylbenzene as a main component, and methylbenzyl alcohol is substantially used. Separating into a fraction free of, and recycling the fraction containing sec-butylbenzene as a main component and substantially free of methylbenzyl alcohol to the oxidation step (C1).

As starting material sec-butylbenzene (C) preferably contains not more than 0.1% by weight, more preferably not more than 0.05% by weight of methylbenzyl alcohol.

The oxidation step (C1) is a step of oxidizing sec-butylbenzel to obtain an oxidation reaction liquid containing sec-butylbenzene hydroperoxide as a main product. This step, for example, reduces the sec-butylbenzene to sec-butylbenzene hydroperoxy by contacting sec-butylbenzene liquid with oxygen-containing gas at a temperature of 90 to 150 ° C and a pressure of ^{1 to 10} kg / cm ² G. Is performed.

In the concentration step (C2), the oxidation reaction solution was distilled to concentrate to obtain a base liquid containing sec-butylbenzene hydroperoxide as a main component at the bottom of the column, containing sec-butylbenzene as a main component, and methylbenzyl alcohol substantially The distillate without furnace is obtained on the column and the distillate is recycled to the oxidation step (C1).

The distillation conditions in the concentration step (C2) are, in short, a base liquid containing sec-butylbenzene hydroxide peroxide as a main component, obtained in the column bottom, containing sec-butylbenzene as a main component, substantially free of methylbenzyl alcohol. The distillate is selected to be obtained from the top of the column. For example, distillation is performed at a column bottom temperature of 50 to 150 ° C. and a column top pressure of 1 to 200 torr. The concentration of methylbenzyl alcohol contained in the distillate containing sec-butylbenzene as a main component recovered in the concentration step (C2) is usually maintained at 0.01% by weight or less.

The decomposition step (C3) is a step of decomposing sec-butylbenzene hydroperoxide into phenol and methyl ethyl ketone by contacting the base liquid of the concentration step (C2) with an acidic catalyst. Acidic catalysts used include sulfuric acid, sulfuric anhydride, perchloric acid and phosphoric acid.

Acidic catalysts are usually used in amounts of 0.01 to 1% by weight. Decomposition temperature is 50-100 degreeC normally.

The neutralization step (C4) is a step of neutralizing the decomposition solution obtained in the decomposition step (C3) with an aqueous alkali solution, separating it into an oil layer and an aqueous layer, and recycling a part of the aqueous layer to the inlet of the thickening step (C4) again. Alkali used for neutralization includes hydroxides, carbonates and bicarbonates of sodium, potassium and lithium. Alkali is usually used in an amount sufficient to maintain the pH of the aqueous layer at 4-11, preferably 4-9. Preferably, the temperature is from room temperature (about 20 ° C) to 90 ° C, and the weight ratio of the oil layer to the aqueous layer is 0.5 to 5. The neutralization step (C4) is carried out so that the liquid layer to be neutralized is brought into complete contact with the aqueous alkali solution and then separated into an oil layer and an aqueous layer. This step is carried out using, for example, a vessel equipped with a stirrer, a line mixer and a pipe mixer column. In neutralization step C4, a portion of the water bed that was used in neutralization step C4 may be recycled and reused in neutralization step C4 to reduce the amount of wastewater. Recycling the aqueous layer consequently increases the salt concentration in the neutralization step (C4). Therefore, it is preferable to maintain the salt concentration normally at 1 to 30% by weight. The oil layer obtained in the neutralization step (C4) is transferred to the subsequent purification step. On the other hand, part of the aqueous layer is recycled to the neutralization step (C4) and the rest is discarded.

Purification step (C5) is a distillation of the oil layer obtained in the neutralization step (C4), a fraction containing phenol as a main component, a fraction containing methyl ethyl ketone as a main component and sec-butylbenzene as a main component, methylbenzyl alcohol This substantially free fraction is separated, and the fraction containing sec-butylbenzene as a main component is recycled to the oxidation step (C1). Distillation, in short, the oil layer obtained in the thickening step (C4) contains a fraction containing phenol as a main component, a fraction containing methyl ethyl ketone as a main component, and sec-butylbenzene as a main component, and substantially free of methylbenzyl alcohol. It is carried out under conditions that can be divided into fractions. This step is usually carried out using a plurality of distillation columns. The amount of methylbenzyl alcohol contained in the fraction containing sec-butylbenzene as a main component recovered in the purification step (C5) is usually kept below 0.05% by weight.

Although the ratio of the amount of liquid recycled from the purification step (C5) to the oxidation step (C1) to the oxidation step (C1) against the concentration step (C2) can be adjusted to be beyond the range in terms of operating conditions And usually about 10: 1 to about 20: 1. Therefore, the concentration of methylbenzyl alcohol in the liquor recycled to the oxidation step (C1) is usually 0.01% by weight or less.

The present invention is described in detail below with reference to Examples.

First, the case where sec-butylbenzyl is selected which is substantially free of (A) ethyl hydroperoxide, carboxylic acid and phenol as starting material is described.

Example A-1

47.6 kg of a liquid mixture of sec-butylbenzene and sec-butylbenzene hydroperoxide substantially free of ethyl hydroperoxide, carboxylic acid and phenol are placed in a 100 liter stainless steel (sec 304) reactor. The content of sec-butylbenzene hydroperoxide in the mixture is adjusted to 1.1% by weight. Nitrogen-diluted air is injected into this liquid mixture with stirring at a rate of 80 N 1 / min to bring the concentration of oxygen to 10% by volume. The oxidation is then carried out for 6 hours at a pressure of 1.5 kg / cm ² G and a temperature of 120 ° C.

After oxidation is complete, the reaction liquid in the reactor is analyzed. The analysis results show that the hydroperoxide concentration of the reaction solution is 10.7 wt%. Condensation of the oxidizing exhaust gas yields 7.2 kg of condensate. The result of analyzing this condensate was 0.54% by weight of hydroperoxide (converted to ethyl hydroperoxide: same applies afterwards) in addition to sec-butylbenzene in which the condensate was a main component. It contains 259 ppm phenol and 7.2 mmol / kg carboxylic acid (76 ppm by weight of formic acid and 339 ppm by weight of acetic acid). Subsequently, 60 g of condensate and 12 g of 1N titanium hydroxide aqueous solution are placed in a 100 ml glass flask and mixed by stirring for 30 minutes with a stirrer while heating at a 40 ° C. hot bath. The resulting mixture is left to stand for 30 minutes and then separated into an oil layer and an aqueous layer. Analysis of the oil layer shows that the oil layer contains 0.1 wt% hydroperoxide, 5 ppm phenol and undetectable amounts of carboxylic acid. The content of hydroperoxide in the aqueous layer is 1.9% by weight.

The results obtained in this example are summarized below.

Alkaline Usage:

NaOH / (ethyl hydroperoxide + carboxylic acid + phenol) = 2.1 (molar ratio).

NaOH / (carboxylic acid + phenol) = 20 (molar ratio).

Removal efficiency of by-products of condensation by alkaline washing:

Ethyl hydroperoxide: (1-0.1 / 0.54) × 100 = 81 (%),

Phenol: (1-5 / 229) x 100 = 98 (%).

Thus, it was proved that ethyl hydroperoxide and phenol were removed very efficiently.

In the above analysis, ethyl hydroperoxide is determined by iodometry, carboxylic acid is determined by ion chromatography (IC 500 type apparatus, manufactured by Yokogawa Works, Ltd .; column SCS 5-252), and phenol is It is determined by liquid chromatography (column: SUMIPAX ODSA -212, 6 mmØ x 15 cmL).

A small amount of sec-butylbenzene hydroperoxide is added as an initiator to the obtained oil layer so that the resulting oil layer contains 1.6 wt% of hydroperoxide. The resulting oil layer is then oxidized in the manner described above. As a result, it was found that during the first two hours, the oxidation rate was approximately equal to the oxidation rate of the foregoing oxidation, and no decrease in oxidation rate was observed.

Comparative Example A-2

A solution containing 10.7% by weight of sec-butylbenzene hydroperoxide obtained in the first oxidation of Example A-1 at a column bottom temperature of 60-70 ° C. and a pressure of 10 Torr was concentrated to 67% by weight of hydroperox The base liquid containing a seed and the distillate containing sec-butylbenzene as a main component are obtained. Analysis of this distillate showed that the distillate contained 0.12 wt% hydroperoxide, 55 ppm phenol and 2.8 mmol / kg carboxylic acid (55 wt ppm formic acid and 95 wt ppm acetic acid).

Subsequently, 7 kg of the condensate of Example A-1, 7 kg of the distillate obtained above, and 0.466 kg of 1N sodium hydroxide aqueous solution were placed in a glass graduated vessel, stirred at 40 ° C. for 30 minutes, mixed, and left to stand for 30 minutes. And separated into aqueous layer. Analysis of the oil layer shows that the oil layer contains 0.15% by weight hydroperoxide, 40 ppm phenol and at least 0.1 mmol / kg carboxylic acid.

The results obtained in this example are summarized as follows.

Alkaline Usage:

NaOH / (ethyl hydroperoxide + carboxylic acid + phenol) = 0.57 (molar ratio),

NaOH / (carboxylic acid + phenol) = 5.0 (molar ratio).

Removal efficiency of by-products of condensation by alkaline washing:

Ethyl Hydroperoxide: (1-0.15 / ((0.54 + 0.12) / 2)) x 100 = 55 (%)

Phenol: (1-40 / ((229 + 55) / 2)) × 100 = 72 (%).

This comparative example shows the case where the alkali washing is performed using an insufficient amount of alkali. In this case, ethyl hydroperoxide, phenol and carboxylic acid were not sufficiently removed.

A small amount of sec-butylbenzene hydroperoxide was added to the obtained oil layer as an initiator so that the resulting oil layer contained 1.6% by weight of hydroperoxide, followed by primary oxidation in the same manner as in Example A-1. As a result, it was found that during the first two hours the oxidation rate decreased to 66% of the oxidation rate of the primary oxidation of Example A-1. Thus, it has been demonstrated that the oxidation rate is significantly reduced by performing alkali washing without satisfying the above limitations.

Example A-3

A 200 ml stainless steel (year 316) autoclave was placed with 100 g of an aqueous layer obtained by treatment with aqueous sodium hydroxide solution in Example A-1 and 0.1 g of a 5 wt% Pd catalyst (NE CHEMCAT COPR.) On A1 ₂ O ₃ . And hydrogenated at a hydrogen pressure of 10 kg / cm ² G and a temperature of 60 ° C. for 3 hours. As a result, the ethyl hydroperoxide conversion rate (reacted ethyl hydroperoxide / poured ethyl hydroperoxide × 100) was 100%, and the ethanol selectivity (ethanol formed (mol) / reacted ethyl hydroperoxide (mol) × 100). ) Was 67%.

Example A-4

The aqueous solution obtained by treatment with aqueous sodium hydroxide solution is neutralized with aqueous sulfuric acid solution before hydrogenation, and the same procedure as in Example A-3 is repeated except that the reaction temperature and reaction time are changed to 100 ° C. and 2 hours, respectively. As a result, ethyl hydroperoxide conversion was 99% and ethanol selectivity was 54%.

Example A-5

100 g of the aqueous layer obtained by treatment with aqueous sodium hydroxide solution in Example A-1 was placed in a 200 ml stainless steel (SUS 316) autoclave and pyrolyzed for 1 hour at a temperature of 150 ° C. and a nitrogen pressure of 10 kg / cm ² G. . As a result, the ethyl hydroperoxide conversion was 100%.

Example A-6

The aqueous solution obtained by treatment with aqueous sodium hydroxide solution is neutralized with aqueous sulfuric acid solution before pyrolysis, and the same method as in Example A-5 is repeated except that the reaction temperature and reaction time are changed to 100 ° C. and 4 hours, respectively. As a result, the ethyl hydroperoxide conversion was 97%.

Next, the case where sec-butylbenzene (B) is substantially free of styrene as a starting material is described.

Example B-1

100 g of a liquid mixture of sec-butylbenzene and sec-butylbenzene hydroperoxide substantially free of styrene are placed in a glass container. The content of sec-butylbenzene hydroperoxide in the mixture was adjusted to 2.0% by weight. The liquid mixture is then heated with vigorous stirring until the liquid temperature reaches 120 ° C. and then oxidized for 7 hours with blowing air at a blowing rate of 500 Nml / min. Analysis of the reaction solution after the reaction shows that the concentration of sec-butylbenzene hydroperoxide is 11.9% by weight.

Comparative Example B-2

The same procedure as in Example B-1 is repeated except that the acid ash liquid mixture is replaced with a liquid mixture of sec-butylbenzene hydroperoxide and sec-butylbenzene containing 5% by weight of α-ethylstyrene. As a result, it can be seen that the reaction solution contains 8.5% by weight of sec-butylbenzene hydroperoxide. Thus, in this comparative example, it was proved that the yield per unit time of sec-butylbenzene hydroperoxide was very low.

Reference Example B-3

Internal diameter of 28mm of vertical reaction tubes located in a 0.1% by weight of palladium is immersed in an average diameter of 3 mm is filled with a hydrogenation catalyst containing 80ml alumina granules, and the temperature of this 80 ℃ and 15kg.cm ² G pressure Used for hydrogenation in The starting material used was a mixed solution containing 59.6 wt% sec-butylbenzene, 32.4 wt% acetophenone, 4.9 wt% α, β-dimethylstyrene, 0.4 wt% α-ethylstyrene and 2.7 wt% other saturated hydrocarbons. The molar ratio of hydrogen to olefin is 5.4. The starting material is fed at a rate of 160 ml / hour, and hydrogen gas is fed at a rate of 120 ml / min (straight at NTP) from the bottom of the reaction tube. The composition ratio of the reaction solution after 60 hours is as follows: 64.8 wt% sec-butylbenzene, 32.83 wt% acetophenone, 0.07 wt% α-methylbenzene alcohol, 0.05 wt% α, β-dimethylstyrene, 0.01-ethylstyrene 0.01 The conversion of% by weight and 2.7% by weight of other saturated hydrocarbons, thus styrene, was 98.9%.

In the intermediate stage of the distillation column packed with Helipac, the obtained semi-agitated solution is fed at a rate of 150 g / hour. The distillation pressure is 100 mmHg and the column top temperature is 105 ° C. The distillate is recovered from the column top at a rate of 100 g / hour. Analysis of the distillate showed that the distillate contained 97.08 wt% sec-butylbenzene, 2.31 wt% acetophenone, 0.01 wt% α-methylbenzene alcohol, 0.04 wt% α, β-dimethylstyrene 0.01 wt% α-ethylstyrene And 0.50% by weight of other saturated hydrocarbons.

Furthermore, the case where sec-butylbenzene is selected which is substantially free of (C) methylbenzyl alcohol as starting material is described below.

Example C-1

150 g of sec-butylbenzene solution containing 1% by weight of sec-butylbenzene hydroperoxide is placed in a glass vessel. The solution is heated to 120 ° C. with vigorous stirring and then oxidized for 9 hours with blowing air at a blow rate of 150 Nml / min. Analysis of the reaction solution after the reaction shows that the concentration of sec-butylbenzene hydroperoxide is 12.26% by weight.

[Example C-2 and Comparative Examples C-3 and C-4]

The same procedure as in Example C-1 was repeated except that the material shown in Table 1 was used as the liquid to be oxidized. The obtained results are shown in Table 1.

The result is as follows. In Examples C-1 and C-2 using sec-butylbenzene substantially free of methylbenzyl alcohol, the oxidation rate was high and a sufficient amount of sec-butylbenzene hydroperoxide was formed. In contrast, in Comparative Examples C-3 and C-4 using sec-butylbenzyl containing a significant amount of methylbenzyl alcohol, the oxidation rate was low and no sufficient amount of sec-butylbenzene hydroperoxide was formed.

TABLE 1

week*

* 1) SHPO: sec-butylbenzene hydroperoxide

* 2) MBA: Methylbenzyl Alcohol

* 3) Relative oxidation rate: Relative oxidation rate when the oxidation rate of Example C-1 is taken as 1, expressed as the ratio of SHPO concentration in the post-oxidation reaction solution to the SHPO concentration of Example C-1.

As mentioned above, the present invention provides a process for preparing phenol and methyl ethyl ketone from sec-butylzenene via sec-butylbenzene hydroperoxide. The present invention prevents the accumulation of undesirable by-products in the production system, enables efficient recycling and reuse of unreacted sec-butylbenzene and maintains high oxidation rates.

Claims (11)

Process for preparing phenol and methyl ethyl ketone, characterized by the following steps: (A1) oxidizing sec-butylbenzene substantially free of ethyl hydroperoxide, carboxylic acid and phenol to obtain a reaction liquid and exhaust gas containing sec-butylbenzene hydroperoxide as a main product, (A2) Cooling the exhaust gas obtained in step (A1) to obtain a condensate containing sec-butylbenzene, ethylhydroperoxide, carboxylic acid and phenol. (A3) The reaction solution obtained in step (A1) was concentrated in a distillation column to obtain a base liquid containing sec-butylbenzene hydroperoxide as a main component at the bottom of the column, sec-butylbenzene, ethyl hydroperoxide, and carbohydrate. Obtaining a distillate containing an acid and a phenol at the top of the column, (A4) the condensate obtained in step (A2) and the distillate obtained in step (A3) with an aqueous alkaline solution, which is washed with ethylhydroperoxide The oil layer consisting of sec-butylbenzene substantially free of seeds, carboxylic acids and phenols is separated into an aqueous layer and the oil layer is recycled to step (A1) so that the amount of alkali in the aqueous alkali solution is present throughout the condensate and distillate. Ranges from 1 to 10 moles per mole of ethyl hydroperoxide, carboxylic acid and phenol as a whole, and 10 to 100 moles per mole of carboxylic acid and phenol present in the total condensate and distillate. The step of so, and (A5) obtained in Step (A3) a sec- butylbenzene hydrochloride by decomposing a base liquid containing as a main component the hydroperoxide to obtain phenol and methyl ethyl ketone. The process according to claim 1, wherein sec-butylbenzene (A1) contains 0.01 to 0.5 wt% ethyl hydroperoxide, 0.01 wt% or less carboxylic acid and 0.001 wt% or less phenol. The amount of alkali in the aqueous alkali solution used in step (A4) is in the range of 2 to 7 moles per mole of the total amount of ethyl hydroperoxide, carboxylic acid and phenol present in the total condensate and distillate. And a range of 10 to 60 moles per one mole of the entire carboxylic acid and phenol present in the condensate and the distillate as a whole. The method according to claim 1, further comprising the following steps: (A6) Hydrogenation solution by hydrogenating the aqueous layer obtained in step (A4) immediately or after neutralization to convert ethyl hydroperoxide to ethanol (A7) distilling the hydrogenation reaction solution obtained in step (A6) in a distillation column to recover ethanol from the top of the column. 5. The process of claim 4, wherein step (A6) comprises performing the hydrogenation in the presence of a hydrogenation catalyst in a temperature range of about 20 ° C. to 150 ° C. and a pressure range of 1 to 30 kg / cm ² G. 6. . 5. The process of claim 4, wherein step (A6) comprises performing hydrogenation in the presence of a hydrogenation catalyst within a temperature range of 40 ° C. to 100 ° C. and a pressure range of 1 to 15 kg / cm ² G. 6. 5. The process of claim 4, wherein step (A6) comprises selecting an amount of hydrogen supplied during hydrogenation in the range of 1 to 10 moles per mole of ethylhydroperoxide. The process of claim 4, wherein step (A6) comprises selecting an amount of hydrogen supplied during hydrogenation in the range of 1 to 5 moles per mole of ethylhydroperoxide. The method of claim 1 further comprising the following steps; (A8) thermally decomposing ethyl hydroxide peroxide by pyrolyzing the aqueous layer obtained in step (A4) immediately or after neutralization. 10. The process of claim 9, wherein step (A8) comprises selecting a pyrolysis temperature in the range of 80 ° C to 200 ° C. 10. The process of claim 9, wherein step (A8) comprises selecting a pyrolysis temperature in the range of 100 ° C to 160 ° C.