WO2005030743A1

WO2005030743A1 - Process for producing propylene oxide

Info

Publication number: WO2005030743A1
Application number: PCT/JP2004/013997
Authority: WO
Inventors: Junpei Tsuji; Masaru Ishino
Original assignee: Sumitomo Chemical Company, Limited
Priority date: 2003-09-25
Filing date: 2004-09-16
Publication date: 2005-04-07
Also published as: JP2005097182A

Abstract

A process for producing propylene oxide which comprises an oxidation step in which cumene is oxidized, an epoxidation step in which the cumene hydroperoxide obtained in the oxidation step is reacted with propylene to obtain propylene oxide and cumyl alcohol, and a step in which the α-methylstyrene obtained in the step of dehydrating the cumyl alcohol is hydrogenated into cumene and this cumene is recycled to the oxidation step, characterized in that the cumene hydroperoxide to be supplied to the oxidation step has not undergone a heat history including a temperature not lower than the temperature (t°C) represented by the following equation (1): t (°C) = 150 - 0.8 × w (1) wherein w is the content of cumene hydroperoxide (wt.%) in the solution containing cumene hydroperoxide.

Description

Manufacturing method of medicinal oxide

The present invention relates to a method for producing propylene oxide. More specifically, the present invention relates to a method for producing propylene oxide which can maintain the activity of a catalyst used in an epoxidation reaction for obtaining propylene oxide from propylene at a high level for a long period of time. Background art

A process for converting propylene to propylene oxide using cumene hydroperoxide obtained from cumene as an oxygen carrier and repeatedly using the cumene is disclosed in Czechoslovak Patent CS1440743, U.S. Patent Although disclosed in specification No. 66000054, etc., the disclosed process is a process comprising an oxidation step, an epoxidation step, and a hydrocracking step. If cumyl alcohol obtained in the epoxidation process is converted to cumene only by hydrocracking, the life of the catalyst used for hydrocracking will be shortened, and the yield of cumene will be reduced, resulting in industrial realization It is hard to say enough. Disclosure of the invention

Under such circumstances, an object of the present invention is to convert propylene to propylene oxide using cumene hydroperoxide obtained from cumene as an oxygen carrier, and to be able to use the cumene repeatedly, and to use propylene to propylene. It is an object of the present invention to provide a method for producing propylene oxide, which has an excellent feature that the activity of a catalyst used in an epoxidation reaction for obtaining an oxoxide can be maintained at a high level for a long period of time. , That is, the present invention relates to a method for producing propylene oxide comprising the following steps, wherein the cumenehydride peroxide used in the epoxidation step has received a heat history of at least the temperature represented by the following formula (1): The present invention relates to a method for producing propylene oxide.

t (.C) = 1 5 0—0.8 xw (1)

w: Cumene Hydride Peroxide content in solution containing cumene hydroperoxide (wt%)

Oxidation step: Step of obtaining cumene hydrooxide by oxidizing cumene

Epoxidation step: Step of reacting cumene hydroperoxide obtained in the oxidation step with propylene to obtain propylene oxide and cumyl alcohol.

Dehydration step: A step of obtaining permethylstyrene by dewatering cumyl alcohol obtained in the epoxidation step in the presence of a dehydration catalyst.

Hydrogenation process: In the presence of a hydrogenation catalyst, a process of hydrogenating methylstyrene to make cumene and recycling it to the oxidation process Best mode for carrying out the invention

The oxidation step is a step of obtaining cumene hydroperoxide by oxidizing cumene. Oxidation of cumene is usually performed by autoxidation with oxygenated 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. Normal reaction, temperature is 50 ~ 200 ° C, reaction pressure is between atmospheric pressure and 5 MPa. In the case of an oxidation method using an additive, the alkaline reagent may be an alkali metal hydroxide such as Na〇H or KOH, or an alkaline earth metal compound or Na ₂ CO ₃ or Na HCO ₃ . For example, alkali metal carbonate or ammonia and (NH ₄ ) ₂ C〇 ₃ , alkali metal ammonium carbonate and the like are used.

In the epoxidation step, propylene oxide and cumyl alcohol are obtained by reacting cumene hydroperoxide obtained in the oxidation step with propylene. This is the process of The epoxidation step is preferably performed in the presence of a catalyst comprising a titanium-containing silicon oxide, 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.

In the present invention, cumenehydrido peroxide used as a raw material in the epoxidation step may be a dilute or concentrated purified product or a non-purified product.

The epoxidation reaction is performed by bringing propylene and cumene hydroperoxide into contact with the catalyst. The reaction can be carried out in a liquid phase using a solvent. The solvent should be liquid at the temperature and pressure of the reaction and be substantially inert to the reactants and products. The solvent may consist of the substances present in the hydroperoxide solution used. For example, when cumene hydridoxide is a mixture of its raw material and cumene, it can be used as a substitute for the solvent without adding a solvent.

The epoxidation reaction temperature is generally 0 to 200 ° C, but a temperature of 25 to 200 ° C is preferred. The pressure may be sufficient to keep the reaction mixture in a liquid state. In general, the pressure should be between 100 and 100 kPa.

The epoxidation reaction can be advantageously carried out using a catalyst in the form of a slurry or fixed bed. For large-scale industrial operations, it is preferred to use a fixed bed. It can be carried out by a batch method, a semi-continuous method, a continuous method, or the like. When the liquid containing the reactants is passed through the fixed bed, the liquid mixture leaving the reaction zone contains no or substantially no catalyst.

The dehydration step is a step in which cumyl alcohol obtained by the epoxidation reaction is used as a dehydration catalyst to obtain monomethylstyrene. The propylene oxide obtained in the epoxidation step is preferably separated from cumyl alcohol before the dehydration step from the viewpoint of obtaining a high propylene oxide yield.Distillation is used as the separation method. be able to. Examples of the catalyst used in the dehydration step include acids such as sulfuric acid, phosphoric acid, and p-toluenesulfonic acid, and metal oxides such as activated alumina, titania, zirconia, silica alumina, and zeolite. Activated alumina is preferred from the viewpoints of separation of water, catalyst life, selectivity and the like.

The dehydration reaction is usually carried out by bringing cumyl alcohol into contact with the catalyst, but in the present invention, hydrogen may be fed to the catalyst in order to carry out the hydrogenation reaction following the dehydration reaction. The reaction can be carried out in a liquid phase using a solvent. The solvent should 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 can be used as a substitute for the solvent without adding a solvent. The temperature of the dehydration reaction is generally 50-450 ° C, but a temperature of 150-300 ° C is preferred. In general, it is advantageous for the pressure to be between 10 and 1000 kPa. The dehydration reaction can be advantageously carried out using a catalyst in slurry or fixed bed form.

In the hydrogenation step, α-methylstyrene and water obtained by the dehydration reaction are supplied to a hydrogenation catalyst, a-methylstyrene is hydrogenated to convert it into cumene, and cumene is recycled as a raw material in the oxidation step to the oxidation step. This is the process of doing.

Examples of the hydrogenation catalyst include catalysts containing a metal of Group 10 or Group 11 of the periodic table, and specific examples thereof include nickel, palladium, platinum, and copper. Palladium or copper is preferred from the viewpoint of suppression of the addition reaction and high yield. Copper-based catalysts include copper, Raney copper, copper 'chromium, copper' zinc, copper-chromium-zinc, copper-silica, copper-alumina, and the like. Examples of palladium hornworm media include palladium-alumina, palladium-silica, palladium-carbon, and the like. One of these catalysts can be used, or a plurality of catalysts can be used.

The hydrogenation reaction is usually carried out by bringing α-methylstyrene and hydrogen into contact with a catalyst. In the present invention, since the hydrogenation reaction is carried out following the dehydration reaction, a part of the water generated in the dehydration reaction is used. It may be separated by oil-water separation or the like, or may be subjected to a hydrogenation catalyst together with α-methylstyrene without separation. Water required for reaction The elementary amount is a force that is equivalent to equimolar to methyl styrene. Normally, the raw material also contains other components that consume hydrogen, and an excess of hydrogen is required. In addition, since the reaction proceeds more rapidly as the partial pressure of hydrogen is increased, a molar ratio of hydrogen to θ! —Methylstyrene of 1 to 10 is usually used. 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 reaction can be carried out in a liquid or gas phase using a solvent. The solvent should be substantially inert to the reactants and products. The solvent may be any material present in the used methyl styrene solution. For example, when -methylstyrene is a mixture of the product, cumene, this can be substituted for the solvent without particularly adding a solvent. The hydrogenation reaction temperature is generally from 0 to 500 ° C, but a temperature of from 30 to 400 ° C is preferred. In general, it is advantageous for the pressure to be between 100 and 1000 kPa. The dehydration reaction and the hydrogenation reaction can be advantageously carried out by a continuous process using a catalyst in the form of a fixed bed. The dehydration reaction and the hydrogenation reaction may use separate reactors, or may use a single reactor. The reactor of the continuous method includes an adiabatic reactor and an isothermal reactor. However, since an isothermal reactor requires equipment for removing heat, an adiabatic reactor is preferable. In the case of a single adiabatic reactor, since the dehydration reaction of cumyl alcohol is an endothermic reaction, the temperature decreases as the reaction proceeds, while the hydrogenation reaction of α-methylstyrene is an exothermic reaction. The temperature rises as it progresses. As a whole, the calorific value is higher, so the outlet temperature is higher than the reactor inlet temperature. The reaction temperature and pressure are selected so that the water contained in the α-methylstyrene solution after the dehydration reaction does not condense. The reaction temperature is preferably from 150 to 30 Ot :, and the reaction pressure is preferably from 100 to 2000 kPa. If the temperature is lower than the above range or the pressure is too high, water may condense at the dehydration reaction outlet, which may lower the performance of the hydrogenation catalyst. If the pressure is too high, it is disadvantageous in the reaction equilibrium of the dehydration reaction. On the other hand, if the temperature is higher than the above range or the pressure is too low, a large amount of gas phase is generated, and the life of the catalyst may be shortened due to fouling or the like, which is disadvantageous. Hydrogen can be fed from either the inlet of the fixed bed reactor or the inlet of the hydrogenation catalyst, but it is preferable to feed hydrogen from the inlet of the fixed bed reactor in view of the activity of the dehydration catalyst. In other words, the constant presence of hydrogen in the dehydration reaction zone promotes the vaporization of water generated by dehydration, increases the equilibrium de-conversion rate, and can obtain a higher conversion rate more efficiently than in the absence of hydrogen. The water generated in the dehydration reaction passes through the hydrogenation catalyst.However, by operating at a level that does not condense as described above, it can be operated at low cost without installing any equipment for removing water. can do. Unreacted hydrogen at the reactor outlet can be recycled and reused after the gas-liquid separation operation. Further, it is possible to separate water generated in the dehydration reaction from the reaction liquid during the gas-liquid separation operation. A part of the obtained reaction liquid (mainly cumene) can be recycled to the reactor inlet for use.

The amount of the dehydration catalyst may be an amount that can sufficiently convert cumyl alcohol, and the conversion of cumyl alcohol is preferably 90% or more. The amount of the hydrogenation catalyst may be an amount capable of sufficiently converting the methylstyrene, and the α-methylstyrene conversion is preferably 98% or more. From the viewpoint of cost, it is preferable that the dehydration catalyst and the hydrogenation catalyst be packed in a single fixed-bed reactor without using a multi-stage reactor. The reactor may be separated into several beds or not separated. If not separated, the dehydration catalyst and the hydrogenation catalyst may be brought into direct contact with each other, but may be partitioned with an intact filler.

In the present invention, it is essential that cumene hydroperoxide to be subjected to the epoxidation step does not receive a heat history of a temperature (t ° C.) or more represented by the following formula (1).

^{t (D C) = 1 5} 0 -. 0 8 xw (1)

W: Cumene Hydride Peroxide content in solution containing cumene hydroperoxide (% by weight)

If the above conditions are not satisfied, cumene hydroperoxide undergoes thermal decomposition to reduce the yield, and produces poisoning substances for the catalyst used in the epoxidation reaction to obtain propylene oxide from propylene. Epoxidation reaction yield The problem of lowering occurs. An oxidation reaction step can be cited as a place where cumene hydroperoxide to be subjected to the epoxidation step may receive a thermal history. In the case where a concentration step or a purification step is provided after the oxidation step, these steps can also be given as steps receiving the heat history.

In the formula (1), w is the content (% by weight) of cumene hydroperoxide in the solution containing the peroxide at the mouth of cumene hydride, and is preferably 5 to 80% by weight. If the content is too low, industrial productivity is low and disadvantageous.On the other hand, if the content is too high, the decomposition reaction proceeds, the yield decreases, and the risk of runaway reaction decreases. Get higher. Example

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

50 g of a cumene solution (peroxide 17.7 mmo1) containing 5.4% by weight cumenehydride peroxide was charged into a autoclave, and charged at 120 ° C and 0.4 MPag at 6 MPa. The mixture was heated and stirred for 0 minutes. Table 1 shows the amounts of thermolytic products, acetofenone (ACP), cumene dimer (DCUM), and formic acid (FOA), which is a poison of the epoxy catalyst, contained in the heated liquid. Show.

Example 2

The procedure was performed in the same manner as in Example 1 except that the heating temperature was 140. The results are shown in Table 1.

Comparative Example 1

The procedure was performed in the same manner as in Example 1 except that the heating temperature was 160 ° C. The results are shown in Table 1.

Comparative Example 2

The procedure was performed in the same manner as in Example 1 except that the heating temperature was 200 ° C. Table 1 shows the results. table 1

Industrial applicability

According to the present invention, propylene can be converted to propylene oxide using cumene / idloperoxide obtained from cumene as an oxygen carrier, and the cumene can be used repeatedly. It is possible to provide a method for producing propylene oxide which can maintain the activity of a catalyst used in an epoxidation reaction for obtaining propylene oxide at a high level for a long period of time.

Claims

The scope of the claims

1. A method for producing propylene oxide comprising the following steps, wherein the peroxide at the mouth of the cumenehydride to be subjected to the epoxidation step receives a heat history at a temperature (t ° C) or higher represented by the following formula (1). A method for producing propylene oxide.

t CO = 1 5 0-0 .8 xw (1)

w: Cumenehydroxide content in solution containing cumene hydroperoxide (wt%)

Oxidation step: Step of oxidizing cumene to obtain cumene hydroperoxide

Epoxidation step: A step of obtaining propylene oxide and cumyl alcohol by reacting cumene hydrogen oxide obtained in the oxidation step with propylene.

Hydrogenation process: In the presence of a hydrogenation catalyst, a process of hydrogenating methylstyrene to cumene and recycling it to the oxidation process

2. The method according to claim 1, wherein w in the formula (1) is 5 to 80% by weight.