JP2004137159A - Method for producing phenol of cumene process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for effectively utilizing a gas discharged from an apparatus for oxidizing cumene with oxygen and providing cumene hydroperoxide and containing oxygen at a reduced concentration as compared with that during feeding in a method for producing phenol of a cumene process. <P>SOLUTION: The method is characterized as follows. A reaction liquid is obtained by an oxidizing step of feeding the cumene and a mixed gas containing the oxygen and an inert gas to an oxidation reactor, oxidizing the cumene with the oxygen and producing a reaction liquid containing the cumene hydroperoxide, a concentrating step of separating the unreacted cumene from the reaction liquid produced in the oxidizing step and obtaining the cumene hydroperoxide, and an acid decomposing step of decomposing the concentrated cumene hydroperoxide with an acid and producing a reaction liquid containing the phenol and acetone. A purification treatment including multistage distillation of the reaction liquid obtained in the acid decomposing step is carried out. In the method for producing the phenol of the cumene process comprising each step of the purification step of obtaining the purified phenol and the acetone, the mixed gas at the reduced oxygen concentration discharged from the oxidation reactor is fed to an apparatus requiring the inert gas in the process. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
[Industrial applications]
TECHNICAL FIELD The present invention relates to a method for producing phenol by cumene method, wherein a gas having a lower oxygen concentration than that supplied from a device exhausted from a device for oxidizing cumene into oxygen by cumene hydroperoxide is effectively used.
[0002]
[Prior art]
The cumene method phenol production process is an oxidation step in which cumene is oxidized by oxygen to generate a reaction solution containing cumene hydroperoxide, and unreacted cumene is separated from the obtained reaction solution to concentrate the cumene hydroperoxide. A concentration step to obtain, an acid decomposition step to acid-decompose cumene hydroperoxide to generate a reaction solution containing phenol and acetone, and a purification step to obtain a purified phenol and acetone by subjecting this reaction solution to a purification treatment Consists of In a typical purification step, the reaction solution in the acid decomposition step is first neutralized and washed with water to remove inorganic components, and then the reaction solution is distilled to separate it into crude phenol and crude acetone. The crude phenol and the crude acetone are further distilled to obtain purified phenol and purified acetone, respectively. During this time, extraction and other purification treatments may be performed. Therefore, the cumen method phenol plant obtains the phenol and acetone purified from the cumene oxidation reactor, the cumene hydroperoxide concentration device in the reaction solution, the cumene hydroperoxide acid decomposition device, and the acid decomposition reaction solution. And a purification device including a neutralization tank, a washing tank, and a distillation tower. In addition to these devices, a large number of storage tanks for temporarily storing a reaction solution, a purified product, and the like at each stage of the reaction and purification are installed in the plant.
[0003]
[Problems to be solved by the invention]
In many petrochemical plants, an inert gas, usually nitrogen gas, is supplied as a seal gas to a gas phase portion of a storage tank. This is to avoid deterioration of the storage in the storage tank due to oxygen, carbon dioxide, moisture and the like when air is mixed in the gas phase, and the formation of explosive gas in the gas phase. The cumene phenol plant is no exception, and in the plant, an inert gas is supplied as a seal gas to the gas phase of the storage tank in all processes from cumene to purified phenol and acetone. As a supply method, a method of constantly flowing an inert gas through the gas phase of the storage tank, or a method of maintaining the gas phase in a pressurized state with the inert gas and replenishing the inert gas when the pressure falls below a predetermined value. Method. In addition, an inert gas is also used for adjusting the pressure of a vacuum distillation tower and other pressure reducing devices. In order to provide these uses, the cumene phenol plant usually uses nitrogen gas as an inert gas, but it is desired to replace it with another one that is available at a lower cost. The present invention seeks to meet this need.
[0004]
[Means for Solving the Problems]
The present inventors have conducted intensive studies in view of the above problems, and as a result, the gas introduced into the oxidation reactor discharged from the oxidation reactor of cumene or the gas whose oxygen concentration is significantly lower than that of the air whose oxygen concentration has been adjusted is nitrogen. The inventors have found that they can be used for storage tanks and pressure regulators instead of gas, and have completed the present invention.
[0005]
That is, the gist of the present invention is to provide an oxidation step in which a mixed gas containing cumene and oxygen and an inert gas is supplied to an oxidation reactor, and oxygen is applied to the cumene to generate a reaction solution containing cumene hydroperoxide. A concentration step of separating unreacted cumene from the reaction solution generated in step 1 to obtain cumene hydroperoxide, and an acid decomposition step of acid-decomposing the concentrated cumene hydroperoxide to generate a reaction solution containing phenol and acetone And subjecting the reaction solution obtained in the acid decomposition step to purification treatment including multi-stage distillation to obtain a purified phenol and acetone. Supplying a mixed gas with reduced oxygen concentration discharged from the reactor to equipment that requires an inert gas in the process It resides in a method which is characterized.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described specifically.
Examples of the mixed gas containing oxygen and an inert gas to be introduced into the oxidation reactor for cumene include air and air having an increased or decreased oxygen concentration, and among them, an air and / or oxygen concentration increased. Air is preferred.
[0007]
The oxidation reactor may carry out the reaction in one stage or may carry out the reaction in two or more stages. In the latter case, a mixed gas containing oxygen and an inert gas is usually additionally supplied at each stage.
The oxidation reaction is preferably performed at 40 to 120 ° C. under normal pressure or under pressure by continuously supplying cumene and a mixed gas containing oxygen and an inert gas to the oxidation reactor.
[0008]
Further, the oxidation reaction may be performed in the presence of a basic compound or an aqueous solution thereof. Examples of the basic compound include sodium carbonate, sodium hydrogen carbonate, sodium hydroxide, potassium carbonate, potassium hydrogen carbonate, potassium hydroxide and the like. The basic compound is used usually in an amount of 0.0001 to 10.0 parts by weight, preferably 0.001 to 5.0 parts by weight, based on 100 parts by weight of the cumene. Further, a small amount of a catalyst such as a hydroperoxide or a transition metal complex may be present.
[0009]
From the oxidation reactor, a gas containing an amount of cumene equivalent to a saturated vapor pressure and having an oxygen concentration lower than the introduced mixed gas is exhausted. By controlling the ratio of cumene to the oxygen-containing gas, the reaction temperature, the residence time, and the like, the oxidation reaction is controlled so that the gas having an oxygen concentration of 0.1 to 8.0% by volume or less is exhausted. preferable. It is more preferable to control the oxygen concentration to be 0.1 to 7% by volume, particularly 0.1 to 6% by volume.
[0010]
In the manufacturing method according to the present invention, the exhaust gas of the above method is used in place of an inert gas in a place where an inert gas is required in the process. The main ones are various storage tanks and decompression devices in the plant. Usually, it is preferable to use an exhaust gas in which the gas discharged from the oxidation reactor is cooled by a heat exchanger or the like to condense the cumene and reduce the cumene concentration to 1000 ppm or less. Further, as described in JP-A-4-334528, the exhaust gas may be further contacted with an oxidation catalyst to burn organic substances before use.
[0011]
Reservoirs include reservoirs of raw materials, reaction products and products in the process, from raw material cumene to product phenol, acetone and α-methylstyrene. For example, cumene, a neutralized product obtained by neutralizing and washing the acid decomposition product obtained by the acid decomposition reaction of cumene hydroperoxide, crude phenol and crude acetone, and crude phenol distilled and separated from the neutralized product And a distillation residue after separating crude acetone, a pyrolysis product of the distillation residue, a mixture containing cumene and α-methylstyrene after separating crude phenol and crude acetone from the pyrolysis product, and purified. Reservoirs for phenol, acetone, α-methylstyrene and the like.
[0012]
The exhaust gas is circulated at a constant flow rate in the gas phase portion of the storage tank, or supplied such that the storage tank under normal pressure or slightly pressurized state maintains a predetermined pressure. Of these, it is preferable to supply to the storage tank under normal pressure or slight pressure.
Examples of the decompression system include a concentration system and a purification system, and among them, a distillation column is preferable.
[0013]
Examples of the distillation tower include a distillation tower for recovering cumene from an oxidation reaction solution of cumene, and a distillation tower for purifying phenol, acetone and α-methylstyrene.
As a method of adjusting the pressure of the distillation column, a method in which exhaust gas is circulated at a constant flow rate in the system to be depressurized, and a method in which a corresponding fixed amount of gas in the system is extracted out of the system, or a method in which the pressure in the system to be depressurized When the pressure decreases, a method of introducing an amount necessary to maintain a predetermined pressure into the system may be used.
[0014]
Note that the above-described method of using exhaust gas can be applied to gas discharged from a production apparatus using an oxygen oxidation reaction such as a method of producing maleic anhydride from butane and a method of producing acrolein or acrylic acid from propylene. .
[0015]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples as long as the gist is not exceeded.
(Example 1)
Air was passed through an oxidation reactor containing cumene containing 1% by weight of cumene hydroperoxide to carry out an oxygen oxidation reaction at 105 ° C. for 4 hours.
[0016]
From this reactor, 82% by volume of gas with respect to the supplied air was discharged. The gas obtained by cooling this gas to 1 ° C. with a heat exchanger and condensing the cumene (hereinafter referred to as “off gas”) had a composition of 3.0 vol% oxygen and 500 vol ppm cumene.
Off-gas was introduced into a cumene hydroperoxide concentrator for pressure adjustment, and distilled at a pressure of 20 kPa-A or less to distill cumene, and a cumene hydroperoxide concentrate was obtained from the bottom of the column.
[0017]
This cumene hydroperoxide concentrate is supplied to an acid decomposer, an off-gas is introduced for pressure control, an acid decomposition reaction is performed by decomposing with sulfuric acid at a pressure of 100 kPa-A or less, and an acid decomposition mixture containing phenol and acetone is produced. Obtained.
This acid-decomposed mixture was mixed with an aqueous sodium hydroxide solution, neutralized, separated into oil and water, and the oil layer was introduced into a storage tank. Off gas was supplied as a seal gas to the gas phase portion of this storage tank. This oil layer was purified by a purification device including several distillation columns to obtain phenol, acetone, α-methylstyrene, and recycled cumene, respectively. Off-gas was used as a gas for adjusting the pressure of the vacuum distillation column. The quality of each product obtained was comparable to that produced using nitrogen gas as the inert gas.

Claims (4)

An oxidation step in which cumene and a mixed gas containing oxygen and an inert gas are supplied to an oxidation reactor to oxidize cumene with oxygen to form a reaction solution containing cumene hydroperoxide. A cumene hydroperoxide to obtain a cumene hydroperoxide by separating the concentrated cumene hydroperoxide to produce a reaction solution containing phenol and acetone by acid decomposition, and an acid decomposition step. In a method for producing phenol by the cumene method including a purification step of obtaining a purified phenol and acetone by subjecting the reaction solution to purification treatment including multi-stage distillation, the oxygen concentration discharged from the oxidation reactor Supplying the reduced mixed gas to a device requiring an inert gas in the process. The method according to claim 1, wherein the mixed gas is air or air having an increased or decreased oxygen concentration, and a gas having an oxygen concentration of 0.1 to 8% by volume is discharged from the oxidation reactor. Supplying the mixed gas having a reduced oxygen concentration to at least one gas phase of a raw material, a reaction product, and a product storage tank in a process from the raw material cumene to the product phenol, acetone and α-methylstyrene. The method according to claim 1 or 2, wherein: 3. The method according to claim 1, wherein the mixed gas having a reduced oxygen concentration is used as a pressure adjusting gas for at least one device maintained at a reduced pressure in the process.