JP4419489B2 - Cumene production method - Google Patents

Description

  The present invention relates to a method for producing cumene. More specifically, the present invention relates to a method for producing cumene, which is characterized in that cumene can be produced efficiently at low cost.

  A method for producing cumene is known in which cumyl alcohol is dehydrated and converted to α-methylstyrene in the presence of a dehydration catalyst, and then α-methylstyrene is hydrogenated and converted to cumene in the presence of a hydrogenation catalyst. Yes (for example, see Non-Patent Document 1). However, known technical information has not always been satisfactory from the viewpoint of efficiently producing cumene at low cost.

European Chemical News Volume 74 Number 1947 5-11 March 2001

  Under such circumstances, the problem to be solved by the present invention is to provide a method for producing cumene, which is characterized in that it can be produced efficiently at low cost.

That is, the present invention relates to a method for producing cumene from cumyl alcohol and hydrogen using a dehydration catalyst and a hydrogenation catalyst, wherein a mixed catalyst of the dehydration catalyst and the hydrogenation catalyst is packed in a reactor, The present invention relates to a method for producing cumene, which is activated alumina and the hydrogenation catalyst is a catalyst containing palladium .

  As described above, according to the present invention, it was possible to provide a method for producing cumene having a feature that it can efficiently produce cumene at low cost.

  The present invention is practiced in a fixed bed reactor.

  The first reaction of the present invention is a reaction in which cumyl alcohol is dehydrated and converted to α-methylstyrene and water in the presence of a dehydration catalyst.

As the dehydration catalyst, activated alumina is used from the viewpoints of catalyst life and selectivity.
Yes.

  The second reaction of the present invention is a reaction in which α-methylstyrene and water obtained by the dehydration reaction are used as a hydrogenation catalyst, and α-methylstyrene is hydrogenated and converted to cumene.

As the hydrogenation catalyst , a catalyst containing palladium is used from the viewpoint of high yield.

  The dehydration and hydrogenation reactions described above can be performed in a liquid phase using a solvent. The solvent must be substantially inert to the reactants and products. The solvent may consist of substances present in the solution used. For example, when cumyl alcohol is a mixture composed of cumene, which is a product, it can be used as a substitute for a solvent without particularly adding a solvent. In addition, useful solvents include alkanes (for example, octane, decane, dodecane) and aromatic monocyclic compounds (for example, benzene, ethylbenzene, toluene).

  The greatest feature of the present invention is that in the method for producing cumene from cumyl alcohol and hydrogen using a dehydration catalyst and a hydrogenation catalyst, a mixed catalyst of the dehydration catalyst and the hydrogenation catalyst is packed in the reactor. . The preferred embodiment is as follows.

  In the present invention, the fixed bed reactor is filled with a mixed catalyst of a dehydration catalyst and a hydrogenation catalyst.

  The mixing ratio of the dehydration catalyst and the hydrogenation catalyst of the mixed catalyst does not need to be uniform throughout the reactor, and can be arbitrarily selected according to the characteristics of the dehydration reaction and the hydrogenation reaction.

  The total amount of the dehydration catalyst charged in the reactor may be an amount that can sufficiently convert cumyl alcohol, and the conversion rate of cumyl alcohol in the entire reactor is preferably 90% or more. Similarly, the total amount of the hydrogenation catalyst may be an amount that sufficiently converts α-methylstyrene, and the α-methylstyrene conversion rate in the whole reactor is preferably 98% or more.

  In the present invention, it suffices that a part of the reactor satisfies the requirements of the present invention, and the dehydration catalyst and the hydrogenation catalyst may be individually and alternately charged in the other parts.

  Hereinafter, the point that the present invention is superior to the two-layer filling of the dehydration catalyst and the hydrogenation catalyst that are usually performed will be described.

  The fixed bed reactor used in the present invention includes an adiabatic reactor and an isothermal reactor, and the isothermal reactor is preferably an adiabatic reactor because equipment for removing heat is required. In the case of an adiabatic reactor, the dehydration reaction of cumyl alcohol is an endothermic reaction, so the temperature decreases as the reaction proceeds. On the other hand, the hydrogenation reaction of α-methylstyrene is an exothermic reaction, so the temperature increases as the reaction proceeds. To rise. As a result, since the calorific value is larger, the outlet temperature is higher than the reactor inlet temperature.

  In the two-layer packing, since the dehydration reaction which is an endothermic reaction is almost completed and hydrogenation which is an exothermic reaction is performed, the temperature difference between the low temperature part and the high temperature part in the reactor becomes very large. Adverse effects such as a decrease in the rate of reaction and a side reaction other than the target being promoted due to a rapid temperature increase in the high temperature part are observed.

  On the other hand, in the method of the present invention, the dehydration reaction, which is an endothermic reaction, and the hydrogenation reaction, which is an exothermic reaction, are apparently performed at the same time. Reduced.

  The reaction temperature and pressure are selected so that water contained in the solution does not condense. The reaction temperature is preferably 150 to 300 ° C., and the reaction pressure is preferably 100 to 2000 kPa. If the temperature is too low or the pressure is too high, water may condense and reduce the performance of the hydrogenation catalyst. If the pressure is too high, it is disadvantageous in the reaction equilibrium of the dehydration reaction. If the temperature is too high or the pressure is too low, a large number of gas phase portions are generated, which is disadvantageous because the catalyst life decreases due to fouling and the like.

  Here, since the temperature distribution in the reactor is smoothed compared with the two-layer filling, the filling method of the present invention has a wide operating range of reaction temperature and pressure, and is advantageous from the above viewpoint.

  In the present invention, in addition to smoothing the temperature distribution, the concentration of α-methylstyrene in the reactor is also kept low, so that side reactions derived from α-methylstyrene (for example, formation of α-methylstyrene dimer) It is suppressed.

  The amount of hydrogen required for the reaction may be equimolar to α-methylstyrene produced by the dehydration reaction, but usually other components that consume hydrogen are also included in the raw material, and excess hydrogen is required. Is done. Further, since the reaction proceeds more rapidly as the partial pressure of hydrogen is increased, 1 to 10 is usually used as the hydrogen / α-methylstyrene molar ratio. More preferably, it is 1 to 5. The excess hydrogen remaining after the reaction can be recycled after being separated from the reaction solution.

The method of the present invention can be carried out as the following dehydration step and hydrogenation step.
Oxidation step: Step of obtaining cumene hydroperoxide by oxidizing cumene Epoxidation step: Step of obtaining propylene oxide and cumyl alcohol by reacting cumene hydroperoxide obtained in oxidation step with propylene Dehydration / hydrogenation Process: α-methylstyrene is obtained by dehydrating cumyl alcohol obtained in the epoxidation process in the presence of a solid catalyst, and the α-methylstyrene is hydrogenated to form cumene. Recycling process

The oxidation step is a step of obtaining cumene hydroperoxide by oxidizing cumene. Cumene is usually oxidized by auto-oxidation with an 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. The normal reaction temperature is 50 to 200 ° C., and the reaction pressure is between atmospheric pressure and 5 MPa. In the case of the oxidation method using an additive, alkaline reagents include alkali metal compounds such as NaOH and KOH, alkaline earth metal compounds or alkali metal carbonates such as Na ₂ CO ₃ and NaHCO ₃ , ammonia, and ( NH ₄ ) ₂ CO ₃ , alkali metal ammonium carbonate and the like are used.

  The epoxidation step is a step of obtaining propylene oxide and cumyl alcohol by reacting cumene hydroperoxide obtained in the oxidation step with propylene.

  As the catalyst, a catalyst comprising a titanium-containing silicon oxide is preferable from the viewpoint of obtaining the target 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 Ti 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.

  Cumene hydroperoxide used as a raw material for the epoxidation process may be a diluted or concentrated purified product or non-purified product.

  The epoxidation reaction is performed by bringing propylene and cumene hydroperoxide into contact with a catalyst. The reaction is carried out in the 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 hydroperoxide solution used. For example, when cumene hydroperoxide is a mixture composed of cumene, which is 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, chlorobenzene, orthodichlorobenzene) and alkanes (eg octane, decane, dodecane).

  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 state. In general, the pressure is advantageously between 100 and 10000 kPa.

  When a solid catalyst is used, it is used for the reaction 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 molar ratio of propylene / cumene hydroperoxide supplied to the epoxidation step is preferably 2/1 to 50/1. If the ratio is too small, the reaction rate is lowered and the efficiency is poor. On the other hand, if the ratio is too large, the amount of propylene recycled is excessive, and a large amount of energy is required in the recovery process.

  In the dehydration and hydrogenation step, cumyl alcohol obtained in the epoxidation step is dehydrated to obtain α-methylstyrene, and hydrogenated to obtain cumene, and the cumene is recycled to the oxidation step as a raw material for the oxidation step. Process, as described above.

  By using the above characteristic method, the problem to be solved by the present invention can be solved.

Claims (2)

In a method for producing cumene from cumyl alcohol and hydrogen using a dehydration catalyst and a hydrogenation catalyst, a mixed catalyst of the dehydration catalyst and the hydrogenation catalyst is packed in the reactor, the dehydration catalyst is activated alumina, and A method for producing cumene, wherein the hydrogenation catalyst is a catalyst containing palladium . The method for producing cumene according to claim 1, wherein the method for producing cumene is a part of a method for producing propylene oxide including the following steps.
Oxidation step: Step of obtaining cumene hydroperoxide by oxidizing cumene Epoxidation step: Step of obtaining propylene oxide and cumyl alcohol by reacting cumene hydroperoxide obtained in oxidation step with propylene Dehydration / hydrogenation Process: α-methylstyrene is obtained by dehydrating cumyl alcohol obtained in the epoxidation process in the presence of a solid catalyst, and the α-methylstyrene is hydrogenated to form cumene. Recycling process