JP2008260756A - Process for producing alkenyl aryl - Google Patents

Abstract

A method for producing alkenyl aryl by subjecting an aryl alcohol raw material liquid containing titanium as an impurity to a dehydration reaction in the presence of an alumina-based dehydration catalyst, which can efficiently obtain alkenyl aryl at low cost. Provided is a method for producing alkenylaryl having an excellent effect of being able to be produced.
A method for producing alkenyl aryl, wherein a titanium concentration in an aryl alcohol raw material liquid is 0.01 to 0.5 (weight ppm). Examples of the alumina-based dehydration catalyst include any alumina-containing dehydration catalyst, activated alumina containing a metal such as activated alumina, copper, zinc and palladium, and a metal such as silica-alumina, copper, zinc and palladium. In view of catalyst life and selectivity, activated alumina is preferred.
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Description

  The present invention relates to a method for producing alkenylaryl. More specifically, the present invention relates to a method for producing alkenyl aryl by dehydrating an aryl alcohol raw material liquid containing titanium as an impurity in the presence of an alumina-based dehydration catalyst. The present invention relates to a method for producing alkenyl aryl having an excellent effect that aryl can be obtained.

  A method for producing alkenyl aryl by subjecting an aryl alcohol raw material liquid to a dehydration reaction in the presence of an alumina-based dehydration catalyst is known (see, for example, Patent Document 1). However, there is no description of a method for producing alkenyl aryl by dehydrating an aryl alcohol raw material liquid containing titanium as an impurity.

  The conventional method requires a considerably high temperature in order to obtain a high yield, and has a problem in terms of efficiently obtaining a high alkenyl aryl at a low cost.

Japanese Patent Publication No.52-39017

  In such a situation, the problem to be solved by the present invention is a method for producing alkenyl aryl by dehydrating an aryl alcohol raw material liquid containing titanium as an impurity in the presence of an alumina-based dehydration catalyst. An object of the present invention is to provide a method for producing alkenyl aryl having an excellent effect that alkenyl aryl can be efficiently obtained at low cost.

  That is, the present invention is a method for producing alkenyl aryl by dehydrating an aryl alcohol raw material liquid containing titanium as an impurity in the presence of an alumina-based dehydration catalyst, wherein the concentration of titanium in the aryl alcohol raw material liquid is Is related to the method for producing alkenylaryl, characterized in that it is 0.01 to 0.5 (weight ppm).

  According to the present invention, there is provided a method for producing alkenyl aryl by dehydrating an aryl alcohol raw material liquid containing titanium as an impurity in the presence of an alumina-based dehydration catalyst, and efficiently obtaining alkenyl aryl at low cost. It is possible to provide a method for producing alkenylaryl having the excellent effect of being able to

  Examples of the alumina-based dehydration catalyst of the present invention may be any alumina-containing dehydration catalyst, and include activated alumina, silica-alumina, copper, zinc, palladium containing metals such as activated alumina, copper, zinc, and palladium. Examples thereof include silica-alumina containing a metal such as activated alumina is preferred from the viewpoint of catalyst life and selectivity.

  The aryl alcohol of the present invention is a compound containing both a hydroxyl group and an aromatic group, and examples thereof include cumyl alcohol, 1-phenylethyl alcohol and the like. -Methylstyrene is obtained, and styrene is obtained from 1-phenylethyl alcohol.

  The raw material liquid subjected to the dehydration reaction of the present invention contains titanium as an impurity, and has a titanium concentration in the raw material liquid of 0.01 to 0.5 (weight ppm). In order to reduce the concentration, removal equipment or the like is required and the cost is high. On the other hand, if the concentration is too high, the conversion rate of the aryl alcohol is remarkably lowered, both of which are disadvantageous. A more preferable titanium concentration is 0.05 to 0.3 (weight ppm).

  The titanium concentration in the raw material liquid can be measured by analyzing the sample by inductively coupled radio frequency plasma (ICP) spectroscopy after dry ashing.

  As the aryl alcohol raw material liquid of the present invention, a liquid obtained by converting alkylaryl hydroperoxide and propylene by reacting them with propylene oxide in the presence of a titanium-based epoxidation catalyst can be used. Here, the following method can be given as a method for converting alkylaryl hydroperoxide and propylene by reacting them with propylene oxide and aryl alcohol in the presence of a titanium-based epoxidation catalyst.

  The epoxidation reaction is performed in a liquid phase using a solvent. The solvent must be liquid under the temperature and pressure during the reaction and be substantially inert to the reactants and products. The solvent may consist of substances present in the alkylaryl hydroperoxide solution used. For example, when cumene hydroperoxide is a mixture comprising cumene as a raw material, it can be used as a substitute for a solvent without adding a solvent. Other useful solvents include aromatic monocyclic compounds (eg benzene, toluene, ethylbenzene, chlorobenzene) and alkanes (eg octane, decane, dodecane).

  As the epoxidation catalyst, a titanium-based epoxidation catalyst is used from the viewpoint of obtaining a target product with high yield and high selectivity. As the titanium-based epoxidation catalyst, a so-called titanium-silica catalyst containing titanium chemically bonded to silicon oxide is preferable. 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, a zeolite compound containing titanium, and the like can be given. 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. Moreover, it can implement by a batch method, a semi-continuous method, a continuous method, etc.

  The epoxidation reaction temperature is generally 0 to 200 ° C, but a temperature of 25 to 200 ° C is preferable. The pressure may be sufficient to keep the reaction mixture in a liquid phase. In general, the pressure is advantageously from 100 to 10,000 kPa.

  The molar ratio of propylene / alkylaryl hydroperoxide supplied to the epoxidation step is preferably 2/1 to 50/1. If the molar ratio is too low, the reaction rate decreases and the efficiency is poor. On the other hand, if the molar ratio is excessive, the amount of propylene that is recycled increases, and a large amount of energy is required in the propylene recovery step.

The dehydration reaction is performed by contacting aryl alcohol with a catalyst. The reaction can be carried out in the gas phase or in the liquid phase using a solvent. The reaction is preferably carried out in the liquid phase from the viewpoint of productivity and energy saving. A solvent may or may not be used. If a solvent is used, it must be substantially inert to the reactants and products.
The solvent may consist of a substance present in the aryl alcohol solution used. For example, when cumyl alcohol is a mixture composed of cumene, which is the raw material, it can be used as a substitute for a solvent without adding a solvent. Other useful solvents include aromatic monocyclic compounds (eg benzene, toluene, ethylbenzene, chlorobenzene) and alkanes (eg octane, decane, dodecane).

  The dehydration reaction temperature is generally 50 to 450 ° C, but a temperature of 150 to 300 ° C is preferable. The pressure is generally 100 to 10,000 kPa, but it is advantageous to carry out at a pressure as low as possible in view of the equilibrium reaction.

  The dehydration reaction can be carried out using a catalyst in the form of a slurry or fixed bed.

  It was found that when an aryl alcohol raw material liquid containing titanium as an impurity was supplied to the dehydration reaction, the activity of the dehydration catalyst was reduced. Titanium contained in the raw material liquid has an adverse effect on the dehydration catalyst. By maintaining the titanium concentration in the range of 0.01 to 0.5 (weight ppm), it is possible to suppress a decrease in the activity of the dehydration catalyst. .

  Examples of a method for maintaining the titanium concentration in the raw material liquid within the range of the present invention include a flash distillation method, an adsorption method, and a cleaning method. An example of a preferable method is an adsorption method. Before supplying the aryl alcohol raw material liquid containing titanium to the dehydration reaction, it is desirable to adjust the titanium concentration within the range of the present invention by adsorbent treatment. Examples of the adsorbent include metal oxides such as activated alumina, silica-alumina, and zeolite, and these can be used alone or as a mixture. The adsorbent can be installed in an adsorbent bed provided upstream of the dehydration reactor filled with the alumina-based dehydration catalyst, or at the inlet of the dehydration reactor filled with the alumina-based dehydration catalyst. Filling the part.

Hereinafter, the present invention will be described in Examples.
Example 1
A metal reactor was charged with 819 g of activated alumina, and the temperature of the activated alumina layer was 233 to 253 ° C., and 30 wt% cumyl alcohol raw material liquid containing titanium (0.15 wt ppm of titanium) was 5.7 kg. / H. At this time, the yield of α-methylstyrene at the outlet of the reactor was 98.5%.

Claims (4)

A process for producing alkenyl aryl by dehydrating an aryl alcohol raw material liquid containing titanium as an impurity in the presence of an alumina-based dehydration catalyst, wherein the titanium concentration in the aryl alcohol raw material liquid is 0.01 to 0 .5 (weight ppm), The manufacturing method of the alkenyl aryl characterized by the above-mentioned. The production method according to claim 1, wherein the aryl alcohol is cumyl alcohol and / or 1-phenylethyl alcohol, and the alkenyl aryl is α-methylstyrene and / or styrene. The production method according to claim 1, wherein the alumina-based dehydration catalyst is activated alumina. The process according to claim 1, wherein the aryl alcohol raw material liquid is obtained by converting alkylaryl hydroperoxide and propylene by reacting them with propylene oxide in the presence of a titanium-based epoxidation catalyst.