JP2003160519A - Method for producing propylene oxide and ethylbenzene - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing propylene oxide from propylene and ethylbenzene by epoxidation without by-producing styrene, and cumene used as a carrier of oxygen can be repeatedly used, and ethylbenzene can be obtained. <P>SOLUTION: The method comprises an oxidation step: cumene is oxidized to obtain cumene hydroperoxide; an epoxidation step: propylene oxide and cumyl alcohol are obtained from the cumene hydroperoxide and propylene; a hydrocracking step: cumene is obtained by hydrocracking the cumyl alcohol obtained in the epoxidation step and cumene is recycled to the oxidation step as a raw material; and an ethylbenzene separation step: ethylbenzene contained in a reaction liquid containing the cumene obtained in the hydrocracking step is separated and recovered. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing propylene oxide and ethylbenzene. More specifically, the present invention relates to the use of cumene, which can epoxidize propylene to produce a desired propylene oxide without co-producing styrene, and constitutes a carrier of oxygen used in epoxidation. The present invention relates to a method for producing propylene oxide and ethylbenzene, which have excellent characteristics that they can produce ethylbenzene. [0002] Propylene is oxidized using ethylbenzene hydroperoxide as an oxygen carrier,
The process for obtaining propylene oxide and styrene is known as the Halcon process. According to this method, styrene is inevitably produced as a by-product together with propylene oxide, which is unsatisfactory from the viewpoint of selectively obtaining only propylene oxide. [0003] Under such circumstances,
The problem to be solved by the present invention is that propylene can be epoxidized and converted to a desired propylene oxide without co-producing styrene, and cumene constituting an oxygen carrier used in the epoxidation is repeatedly used. And a process for producing propylene oxide and ethylbenzene, which has an excellent feature that it can obtain industrially useful ethylbenzene from impurities generated by decomposition of cumene hydroperoxide used as an oxygen carrier. It is in the point of doing. That is, the present invention relates to a method for producing propylene oxide and ethylbenzene, comprising the following steps. Oxidation step: Step of obtaining cumene hydroperoxide by oxidizing cumene Epoxidation step: Reaction of cumene hydroperoxide obtained in the oxidation step with propylene in the liquid phase in the presence of a solid catalyst to form propylene Step of obtaining oxide and cumyl alcohol Hydrogenolysis step: Cumene alcohol generated in the epoxy step is hydrocracked to obtain cumene, and the cumene is recycled to the oxidation step as a raw material for the oxidation step. Ethylbenzene separation step: A step of separating and recovering ethylbenzene contained in a reaction solution containing cumene obtained in the hydrocracking step. DETAILED DESCRIPTION OF THE INVENTION The oxidation step of the present invention comprises the step of oxidizing cumene, This is a step of obtaining peroxide. The oxidation of cumene is usually performed by auto-oxidation with oxygen-containing gas such as air or oxygen-enriched air. This oxidation reaction may be carried out without using an additive, or an additive such as an alkali may be used. Typical reaction temperature is 50
２００200 ° C. and the reaction pressure is between atmospheric pressure and 5 MPa. In the case of the oxidation method using an additive, an alkaline metal compound such as NaOH or KOH, an alkaline earth metal compound or Na ₂ CO ₃ or NaH
An alkali metal carbonate such as CO ₃ or ammonia and (NH ₄ ) ₂ CO ₃ , an alkali metal ammonium carbonate or the like is used. In the epoxidation step of the present invention, propylene oxide and cumyl alcohol are reacted by reacting cumene hydroperoxide obtained in the oxidation step with an excess amount of propylene in a liquid phase in the presence of a solid catalyst. This is the step of obtaining. [0007] As the catalyst, a catalyst comprising a titanium-containing silicon oxide is preferred from the viewpoint of obtaining the desired product with high yield and high selectivity. These catalysts are preferably so-called Ti-silica catalysts containing Ti chemically bonded to silicon oxide. For example, a titanium compound supported on a silica carrier, a compound compounded with silicon oxide by a coprecipitation method or a sol-gel method, or a zeolite compound containing Ti can be used. In the present invention, cumene hydroperoxide used as a raw material in the epoxidation step is:
It may be dilute or concentrated purified or unpurified. The epoxidation reaction is carried out by bringing propylene and cumene hydroperoxide into contact with a catalyst. The reaction is carried out in a liquid phase using a solvent. The solvent must be liquid at the temperature and pressure of the reaction and must be substantially inert to the reactants and products. The solvent may consist of a substance present in the hydroperoxide solution used. For example, when cumene hydroperoxide is a mixture of the raw material and cumene, it can be used as a substitute for the solvent without particularly adding a solvent. Other useful solvents include aromatic monocyclic compounds (eg, benzene, toluene, chlorobenzene, orthodichlorobenzene) and alkanes (eg, octane, decane, dodecane). [0010] The epoxidation reaction temperature is generally 0 to 200 ° C.
However, a temperature of 25 to 200 ° C. is preferred. The pressure is
The pressure may be sufficient to keep the reaction mixture in a liquid state.
In general, it is advantageous for the pressure to be between 100 and 10000 kPa. The solid catalyst can be advantageously carried out in the form of a slurry or a fixed bed. For large-scale industrial operations, it is preferred to use a fixed bed. Batch method, semi-continuous method,
It can be performed by a continuous method or the like. When the liquid containing the reactants is passed through the fixed bed, the liquid mixture exiting the reaction zone contains no or substantially no catalyst. Propylene supplied to the epoxidation step /
The molar ratio of cumene hydroperoxide is 2/1 to 50
/ 1 is preferred. If the ratio is too low, the reaction rate will decrease and the efficiency will be poor, whereas if the ratio is too high, the amount of propylene recycled will be too high, requiring a large amount of energy in the recovery step. The hydrocracking step of the present invention is a step in which cumene is obtained by hydrocracking the cumyl alcohol obtained in the epoxidation step, and the cumene is recycled to the oxidation step as a raw material for the oxidation step. That is, the same hydrogen as cumene used in the oxidation step is regenerated by hydrocracking. The hydrocracking reaction is usually performed by bringing cumyl alcohol and hydrogen into contact with a catalyst. The reaction can be carried out in a liquid or gas phase using a solvent. The solvent must be substantially inert to the reactants and products. The solvent may consist of the substances present in the cumyl alcohol solution used. For example, when cumyl alcohol is a mixture of the product, cumene, it is possible to substitute the solvent without adding a solvent. Other useful solvents are alkanes (eg octane, decane, dodecane)
And aromatic monocyclic compounds (for example, benzene, ethylbenzene, and toluene). The hydrocracking reaction temperature is generally from 0 to 500C, but from 30 to 400C.
Is preferred. Generally pressure is 100 ~ 10000k
Advantageously, it is Pa. The hydrocracking reaction can be advantageously carried out using a catalyst in the form of a slurry or a fixed bed. As the catalyst, any catalyst having a hydrogenation ability can be used. Examples of the catalyst include a Group 8A metal-based catalyst such as cobalt, nickel and palladium, and a catalyst such as copper and zinc.
Although group B and group 2B metal catalysts can be used, it is preferable to use a copper catalyst from the viewpoint of suppressing by-products. Examples of the copper catalyst include copper, Raney copper, copper-chromium, copper-zinc, copper-chromium-zinc, copper-silica, copper-alumina, and compounds containing these. The method of the present invention can be carried out by a batch, semi-continuous or continuous method. When the liquid or gas containing the reactants is passed through the fixed bed, the liquid mixture exiting the reaction zone contains no or substantially no catalyst. The ethylbenzene separation step of the present invention is a step of separating and recovering ethylbenzene contained in the reaction solution containing cumene obtained in the hydrocracking step. Ethylbenzene is a compound formed as a result of the decomposition of cumene hydroperoxide to produce acetophenone in the oxidation and epoxidation steps, and the acetophenone is hydrogenated in the hydrocracking step.
Ethylbenzene is a component accumulated in the system.If recycling is continued, the concentration will increase with time, the effective reaction volume of each step will decrease, and the reaction of the epoxidation step will be inhibited by byproducts derived from ethylbenzene. There is a disadvantage that the by-products can be impurities in propylene oxide. In view of effective utilization of the reaction volume and suppression of by-products, the concentration of ethylbenzene in the solution containing cumene recycled to the oxidation step is usually controlled to be 0.1 to 5% by weight. Methods for separating and recovering ethylbenzene include distillation, extraction, and the like. As a specific condition, a method of separating ethylbenzene having a purity of 99% or more using two distillation columns can be given. Hereinafter, description will be made with reference to FIG. That is, the hydrocracking reaction liquid [11] is fed to the first distillation column (6) to separate the component [12] rich in cumene at the bottom thereof. The overhead liquid [13] rich in the generated water is fed to the second distillation column (7) to separate light-boiling impurities and the component [14] rich in the generated water from the top of the column, and then from the bottom. This is a method to obtain the product ethylbenzene [15]. The first distillation column (6) has about 10 to 100 theoretical plates, and is operated at a pressure in the range of 0.001 MPa to 1.0 MPa. The second distillation column (7) has a theoretical plate number of about 10 to 1
00 stage, pressure is 0.001MPa ~ 1.0MPa
Is operated within the range. Further, as a specific condition having high energy efficiency, there is a method of separating ethylbenzene having a purity of 99% or more using three distillation columns. Hereinafter, description will be made with reference to FIG. That is, the hydrogenolysis reaction solution [11] is fed to the distillation column (8), and the cumene-rich component [17], a part of the water [18], and ethylbenzene are fed to the bottom of the distillation column. Ethylbenzene and cumene concentrated to 5 to 50 times the amount of the above, and the overhead liquid [16] rich in light boiling impurities and product water [16] is fed to the distillation column (9), and the cumene-rich component [20] is added from the bottom thereof. , Ethylbenzene and light-boiling impurities and product water, the top liquid [19] is fed to a distillation column (10) to separate a light-boiling impurity and product-water-rich component <21> from the top, Product ethylbenzene <2 from the bottom
2> Since the separation of ethylbenzene and cumene is easier as the concentration of produced water is lower, the concentration of produced water is higher and the separation efficiency is lower. It is advantageous in terms of energy efficiency to concentrate ethylbenzene. The first distillation column (8) has about 10 to 10 theoretical plates.
100 stages, pressure is 0.001MPa ~ 1.0MP
It is operated in the range of a. The second distillation column (9) has about 10 to 100 theoretical plates and a pressure of 0.001M.
Operated in the range of Pa to 1.0 MPa. The third distillation column (10) has about 10 to 100 theoretical plates,
The pressure is operated in the range of 0.001 MPa to 1.0 MPa. Further, the second distillation column (9) and the third distillation column (10) can be combined and purified by one distillation column, and the product ethylbenzene can be taken out as a side cut fraction. If cumene recycled from the bottoms of the first distillation column (8) and the second distillation column (9) to the oxidation step contains heavy components, a separation step may be provided. Good. As described above, according to the present invention, propylene can be epoxidized to produce a desired propylene oxide without co-producing styrene, and the oxygen carrier used in the epoxidation can be used. Thus, a method for producing propylene oxide and ethylbenzene having an excellent feature that cumene constituting the polymer can be used repeatedly and ethylbenzene can also be obtained can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of a flow of a method for producing propylene oxide and ethylbenzene according to the present invention (when two distillation columns are used). FIG. 2 is an example of a flow of a method for producing propylene oxide and ethylbenzene according to the present invention (when three distillation columns are used). [Description of Signs] (1) Oxidation step (2) Epoxy step (3) Propylene recovery step (4) Separation of propylene oxide and cumyl alcohol (5) Hydrocracking step (6) Separation of ethylbenzene and cumene (7) Separation of ethylbenzene, light-boiling impurities and generated water (8) Preconcentration of ethylbenzene (9) Separation of ethylbenzene and cumene (10) Separation of ethylbenzene, light-boiling impurities and generated water [1] Cumene (fresh feed) [2] Oxygen Source [3] Cumene hydroperoxide [4] Propylene (fresh feed) [5] Propylene (recycle) [6] Epoxidation step reaction liquid [7] Propylene oxide [8] Cumyl alcohol-containing reaction liquid [9] Hydrogenation Cracking feed solution [10] Hydrogen [11] Hydrocracking reaction solution [12] Cumene (recycle) 13] Ethylbenzene-containing overhead liquid [14] Light boiling impurities, water [15] Ethylbenzene [16] Ethylbenzene concentrated liquid [17] Cumene (recycle) [18] Produced water [19] Ethylbenzene-containing overhead liquid [20] Cumene ( Recycle) <21> Light boiling impurities, water <22> Ethylbenzene

   ────────────────────────────────────────────────── ─── Continuation of front page    F term (reference) 4C048 AA01 BB02 CC01 XX02                 4H006 AA02 AC11 AD11 BA05 BA61                       BE20                 4H039 CA19 CB40 CE40

Claims (1)

Claims: 1. A method for producing propylene oxide and ethylbenzene, comprising the following steps. Oxidation step: Step of obtaining cumene hydroperoxide by oxidizing cumene Epoxidation step: Reaction of cumene hydroperoxide obtained in the oxidation step with propylene in the liquid phase in the presence of a solid catalyst to form propylene Step of obtaining oxide and cumyl alcohol Hydrogenolysis step: Cumene alcohol generated in the epoxy step is hydrocracked to obtain cumene, and the cumene is recycled to the oxidation step as a raw material for the oxidation step. Ethylbenzene separation step: Separation and recovery of ethylbenzene contained in the reaction solution containing cumene obtained in the hydrocracking process