JP2000026439A - Production of propylene oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing propylene oxide by reacting propylene with hydrogen peroxide. SOLUTION: In a method for producing propylene oxide by oxidizing propylene with hydrogen peroxide in the presence of a titanosilicate catalyst, hydrogen peroxide obtained from the extraction process in an alkylanthraquinone method without distillation purification and containing <=150 wt.ppm of a stabilizer is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing propylene oxide, which is an epoxidized product of propylene. More particularly, the present invention relates to a method for economically producing propylene oxide by reacting propylene with hydrogen peroxide.

[0002]

2. Description of the Related Art Propylene oxide is an important industrial raw material as a raw material for propylene glycol, polypropylene glycol and the like. Conventionally known industrial methods for producing propylene oxide include the chlorhydrin method, the Halcon method, and the peracetic acid method.However, these methods produce large amounts of by-products, so it is necessary to secure a market for co-products There was a problem.

[0003] On the other hand, the method using hydrogen peroxide as an oxidizing agent is an ideal method free from the above-mentioned problems because water is a by-produced substance. In particular, it is known that a method using titanosilicate as a catalyst can epoxidize an olefin with high yield and high selectivity using hydrogen peroxide as an oxidizing agent (Japanese Patent Publication No. 4-5028, US Pat.
875). However, in the industrial hydrogen peroxide production method based on the alkylanthraquinone method, organic impurities are removed and hydrogen peroxide is concentrated by distilling the aqueous solution of hydrogen peroxide obtained in the extraction step, and various stabilizers are added. As a result, the long-term stability of hydrogen peroxide is ensured. Hydrogen peroxide is relatively expensive as an oxidizing agent, and as a result, the production cost of propylene oxide is high, and there is a problem that it cannot compete with the above-mentioned current method in terms of cost. Further, the titanosilicate catalyst gradually deteriorates over a long period of use, and the original activity may not be recovered even by calcination. Therefore, the ratio of the expensive titanosilicate catalyst to the production cost of propylene oxide cannot be ignored, which further reduces the cost competitiveness of this method.

[0004] In order to solve this problem, a method for producing propylene oxide inside an oxidation tower by adding a titanosilicate catalyst to an oxidation tower of an alkylanthraquinone method and introducing propylene together with oxygen or air. For producing propylene oxide in the presence of a titanosilicate catalyst using an alcoholic solution of hydrogen peroxide obtained by catalytically reacting hydrogen and oxygen in an alcoholic medium (Japanese Patent Application Laid-Open No. 10-67506) Etc. have been proposed. In the former method, a step of separating and regenerating the titanosilicate catalyst and a step of separating and removing by-product diol and the like are required, and the process becomes very complicated. In addition, the latter method has the disadvantage that the concentration of hydrogen peroxide in the alcohol medium is very low, and consequently the production efficiency of propylene oxide is very low.Moreover, when producing hydrogen peroxide from hydrogen and oxygen, Propylene oxide is easily ring-opened due to the acid used for (1), resulting in poor selectivity.

[0005]

SUMMARY OF THE INVENTION The present invention aims to solve the problems associated with the prior art as described above, and provides a method for producing propylene oxide at a low production cost and at a high yield. It is intended to be.

[0006]

Means for Solving the Problems The present inventors have continued intensive studies in view of the above-mentioned current situation, and completed the present invention.
That is, the present invention relates to a method for producing propylene oxide by oxidizing propylene with hydrogen peroxide in the presence of a titanosilicate catalyst, wherein the propylene oxide is obtained without distillation purification from an extraction step by an alkylanthraquinone method, and contains a stabilizer. The present invention relates to a method for producing propylene oxide, characterized by using hydrogen peroxide having an amount of 150 ppm by weight or less (in terms of 100% hydrogen peroxide).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing propylene oxide according to the present invention will be specifically described. (1) Production of aqueous solution of hydrogen peroxide In the present invention, a known alkylanthraquinone method can be used. That is, a solution obtained by dissolving a 2-alkylanthraquinone in an appropriate solvent is used as a working solution,
First, in the hydrogenation step, the second 2-alkylanthraquinone is catalytically reduced to the corresponding 2-alkylanthrahydroquinone. Next, the working solution containing the 2-alkylanthrahydroquinone is led to an oxidation step, and is oxidized using oxygen or air in an oxidation tower to regenerate the 2-alkylanthraquinone and generate hydrogen peroxide at the same time. The generated working solution containing hydrogen peroxide is extracted with water in the next extraction step to obtain a hydrogen peroxide aqueous solution. The working solution after the extraction is recycled to the hydrogenation step.

The 2-alkylanthraquinone which can be used here is 2-ethylanthraquinone,
-Butyl anthraquinone, 2-amyl anthraquinone and the like can be used. As the solvent for dissolving the 2-alkylanthraquinone, a solvent that is stable against oxidation and reduction and has an extraction coefficient with respect to water as high as possible when extracting the generated hydrogen peroxide with water is used. Also,
In order to dissolve 2-alkylanthraquinone and 2-alkylanthrahydroquinone at a high concentration, a mixed solvent composed of two or more kinds is generally preferred. Examples of such mixed solvents include, but are not limited to, C5-C11
A mixture of an alkylated benzene and a C7 to C11 secondary alcohol, and a mixture of a C5 to C11 alkylated benzene, an alkyl urea and an alkyl phosphoric acid.

The operating conditions of the reduction step are not particularly limited, but are generally in the presence of a catalyst such as a palladium catalyst, a platinum catalyst or a nickel catalyst in a temperature range of 10 to 80 ° C. and a pressure range of 1 to 5 atm. And a method of reducing using hydrogen or a hydrogen-containing gas. As the form of the reaction apparatus, a fixed bed type reaction apparatus, a fluidized bed type reaction apparatus, a stirring type reaction apparatus and the like can be adopted without limitation.

In order to industrially use the working solution in which the 2-alkylanthraquinone is dissolved, it is necessary to produce a 2-alkylanthraquinone from the 2-alkylanthraquinone by catalytic reduction in the hydrogenation step. It is desirable to regenerate the product into an effective form such as a 2-alkylanthraquinone or 2-alkylanthrahydroquinone.

[0011] The extraction step is performed by a known method, that is, a mixer
Settler, countercurrent multistage extraction, and the like can be used. In general, a stabilizer or the like for suppressing the decomposition of hydrogen peroxide may be added to the water used for extraction. In the present invention, it is preferable to use pure water to which no such stabilizer is added. Usually, hydrogen peroxide after extraction is purified by distillation, but since the decomposition of hydrogen peroxide is promoted by distillation, various stabilizers are added. Is used for the production of propylene oxide without distillation. That is, the content of the stabilizer contained in the hydrogen peroxide of the present invention is desirably 150 ppm by weight or less (in terms of 100% hydrogen peroxide). Here, examples of the stabilizer include common phosphates, polyphosphates (such as sodium pyrophosphate and sodium tripolyphosphate), stannates, picolinic acid, ascorbic acid, ethylenediaminetetraacetic acid, nitrotriacetic acid,
Complexing agents such as aminotriacetic acid, diethylenetriaminepentaacetic acid, ethylenediaminetetra (methylenephosphonic acid), and diethylenetriaminopenta (methylenephosphonic acid) are exemplified.

(2) Production of Propylene Oxide As the catalyst used in the synthesis of propylene oxide in the present invention, titanosilicate is preferably used. The titanosilicate is obtained by substituting a part of silicon of crystalline silicalite having a zeolite structure with titanium. The method for synthesizing titanosilicate used in the present invention is not particularly limited.
-96720. The titanosilicate having a Si / Ti ratio of 10 to 1000 is used.

In the present invention, the amount of the titanosilicate catalyst used is not particularly limited. In the case of a suspension bed system, it is usually used in the range of 0.1 to 10% by weight in the reaction solution. . The catalyst may be in any form such as fine powder or pellets, and the reaction can be carried out in either a continuous system or a batch system, and the reaction apparatus can be a suspension bed or fixed bed system.

In the reaction, propylene oxide is dissolved in a solvent in which a titanosilicate catalyst is suspended, and the above hydrogen peroxide is mixed and reacted. Alcohols and ketones are preferably used as the solvent that can be used in the present invention. Specifically, examples of the alcohol include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, 2-butanol, and t.
-Butanol and the like. Among them, methanol is most preferably used. Examples of the ketone include acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, ethyl propyl ketone, dipropyl ketone, and the like. Alcohols and ketones can be used as a mixture.

[0015] The reaction temperature is 5 ° C to 150 ° C, preferably 3 ° C.
It is generally carried out in the range of 0 ° C to 100 ° C. The pressure of propylene is not particularly limited, but is from atmospheric pressure to 100 kg.
/ Cm ² , especially in the range of 3 to 30 kg / cm ² .

[0016]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the following examples.

Example 1 A working fluid obtained by dissolving 2-amylanthraquinone in a solvent was
After reducing with a hydrogen gas in the presence of a silica catalyst carrying palladium in a reduction tower to form a solution containing 2-amylanthrahydroquinone, the catalyst was filtered and introduced into the next oxidation tower, and air was introduced at a pressure of 4 kg / cm ² . To obtain a working solution containing hydrogen peroxide and 2-amylanthraquinone. Hydrogen peroxide was extracted from the working solution with pure water in the next stage extraction tower, and 30% by weight was extracted.
A hydrogen peroxide aqueous solution having a concentration of was obtained. At this time, the content of phosphoric acid and pyrophosphoric acid in the aqueous hydrogen peroxide solution was 100 ppm by weight. TOC (total organic carbon) is 500
It was ppm by weight.

200 cc of methanol and 6 g of a titanosilicate catalyst were charged into an autoclave having an internal volume of 500 cc, and propylene was injected under pressure to a pressure of 4 kg / cm 2. When the solution was heated to 40 ° C., 100 g of the above-mentioned hydrogen peroxide was dropped over 1 hour using a plunger pump. Since the pressure of propylene decreases with the progress of the reaction, the pressure is always 4 kg / cm ² using a constant pressure valve.
Propylene was additionally supplied so that the pressure became.

After completion of the dropwise addition, stirring was continued for another 30 minutes, and then the solution was taken out and the concentration of hydrogen peroxide in the system was determined by an iodine titration method. The produced propylene oxide was quantified by gas chromatography. The conversion of hydrogen peroxide is 95% and the selectivity of propylene oxide is 9%.
It was 0%.

Example 2 The same operation as in Example 1 was repeated, using the titanosilicate catalyst used in Example 1 after filtration, as it was. 1
From the analysis of the reaction solution after repeating 0 times, the conversion of hydrogen peroxide was 93%, the selectivity for propylene oxide was 92%, and the deterioration of the catalyst was hardly observed.

Comparative Example 1 The same operation as in Example 1 was carried out, except that a commercially available 31% by weight aqueous hydrogen peroxide solution containing a hydrogen peroxide stabilizer was used. The hydrogen peroxide aqueous solution had a stabilizer content of 300 ppm by weight (100% hydrogen peroxide conversion) and a TOC of 1%.
It was 00 ppm. Hydrogen peroxide conversion of the first batch is 9
9% and a selectivity of propylene oxide based on hydrogen peroxide of 91% gave almost the same reaction results as in Example 1, but as in Example 2, the reaction was repeated 30 times.
The hydrogen peroxide conversion of the 30th batch was 85%, and the propylene oxide selectivity based on hydrogen peroxide was 90%, indicating a remarkable decrease in the hydrogen peroxide conversion. 5 deteriorated catalyst
The sintering and regeneration treatment was performed at 50 ° C. for 2 hours in air, but no activity was recovered.

[0022]

According to the present invention, deterioration of the titanosilicate catalyst can be suppressed, and propylene oxide can be produced at low cost.

Claims (1)

[Claims] 1. A method for producing propylene oxide by oxidizing propylene with hydrogen peroxide in the presence of a titanosilicate catalyst, wherein the propylene oxide is obtained from an extraction step by an alkylanthraquinone method without purification by distillation and contains a stabilizer. Using a hydrogen peroxide having a content of 150 ppm by weight or less (in terms of 100% hydrogen peroxide).