JPH01132573A - Propylene oxide manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for producing propylene oxide.

(Prior art) As a conventionally proposed method for producing propylene oxide from propylene and hydrogen peroxide, (+) an acid catalyst, hydrogen peroxide, and propionic acid are mixed at 10 to 70%
After producing perpropionic acid by reacting at °C and extracting perpropionic acid from the resulting reaction mixture with benzene, propane dichloride, etc.,
A method of producing propylene oxide by reacting with excess propylene at a pressure of 100 kg/cd (for example,
-38231, Special Publication No. 59-38232, Special Publication No. 597
(2) Hydrogen peroxide and a carboxylic acid in the presence of an inert organic solvent that can form a heteroazeotrope with water. The water present in the reaction mixture is removed by azeotropic distillation to obtain a percarboxylic acid, and then propylene oxide is produced in the same manner as in (1) (for example, according to JP-A-56-18973). )
(3) A method of epoxidizing hydrogen peroxide and propylene at 0 to 120°C using boron oxide, a boron oxyacid, or a boron oxyacid ester as an epoxidation catalyst; A method in which water introduced together with hydrogen oxide and water produced by the reaction are continuously removed from the reaction medium (for example, Japanese Patent Publication No. 5B-50990); (4) Propylene and hydrogen peroxide are removed in the presence of an arsenic catalyst; A method of mixing and reacting at a temperature of 25 to 200 ° C to produce propylene oxide, or a method of continuously removing water by azeotropic dehydration as in (3) (for example,
Japanese Patent Publication No. 53-44442, Japanese Unexamined Patent Application Publication No. 53-95901) are known.

[Problem that the invention seeks to solve]

However, in method (1) above, in order to extract perpropionic acid from the reaction solution in high yield, a large amount of solvent and a large amount of (
The number of extraction stages is required. Further, a large amount of energy and equipment are required to separate and purify propylene oxide from the epoxidation reaction solution, and to recover and circulate the solvent. Furthermore, since percarboxylic acid is practically used at a concentration of 20 to 30% or more, there is a possibility of concentration of diacyl peroxide as a by-product, which has a very high risk of explosion, which is a safety problem.

RCOOOH+ RCOOH→RCOO-00CR+
HxOThe above method (2) removes water in the reaction mixture by azeotroping with the organic solvent, so it is superior in terms of the yield of perpropionic acid based on hydrogen peroxide.
Similar to 1), purification of propylene oxide, recovery of solvent,
Problems such as by-product of diacyl peroxide remain.

In methods (3) and (4) above, strong acids are not used as catalysts, so side reactions such as ring-opening of the generated epoxide are prevented as described in (1).
, has the advantage that it can be kept low compared to method (2), but since the epoxidation power of hydrogen peroxide itself is extremely weak compared to percarboxylic acid, it cannot be used under the same conditions as methods (1) and (2) above. The conversion rate of hydrogen peroxide is low. - The conversion rate of hydrogen peroxide improves by increasing the reaction temperature, pressure, etc., but the selectivity of propylene oxide decreases due to ring opening of propylene oxide. There are problems such as the need to recover the catalyst due to economic efficiency and safety issues, and the process becomes complicated.

An object of the present invention is to provide a highly safe method for directly producing propylene oxide that does not cause concentration of percarboxylic acid.

[Means and effects for solving the problems] The present inventors have made various studies to solve the above problems, and as a result, have finally completed the present invention.

That is, the present invention uses a solvent that forms a heteroazeotrope with water as a solvent and is inert to hydrogen peroxide and propylene oxide, and in the presence of an organic monocarboxylic acid, propylene and hydrogen peroxide are mixed together. When manufacturing propylene oxide from This is a method for producing propylene oxide, which is characterized by the step of extracting propylene oxide.

The multistage reaction column used in the present invention may be a conventional distillation column type such as a plate column or a packed column. Reaction liquid residence time T in the multi-stage reaction tower and reaction liquid residence time T at the bottom!
It is desirable that the relationship between the two satisfies the following formula: RT, / (T, +T), R≧0.2T1: Reaction liquid residence time in the multistage reaction tower T! : R≧0.4 is more preferable than the residence time of the reaction liquid in the bottom. When R is less than 0.2, the production of propylene oxide decreases.

T + + T z is desirably within 1 to 2 hours, and if it is less than 1 hour, the reaction efficiency of hydrogen peroxide will be poor. If the time exceeds 2 hours, the decomposition loss of hydrogen peroxide increases and the production efficiency deteriorates.

As the carboxylic acid used in the present invention, organic monocarboxylic acids having 2 to 8 carbon atoms such as acetic acid, propionic acid, butyric acid, isobutyric acid, and benzoic acid are suitable.

The reaction temperature varies depending on the monocarboxylic acid used, but is 40 to 120°C, preferably 50 to 90°C. Below 40°C, the propylene epoxidation rate is slow and propylene oxide is insufficiently produced;
If the temperature exceeds 20"C, hydrogen peroxide may decompose without participating in the reaction, or the generated propylene oxide may open its ring to promote side reactions to form propylene glycol, etc., which is undesirable because propylene oxide selectivity decreases. The zero reaction pressure is not particularly limited, but normal pressure to slightly increased pressure is preferred.

As the solvent, a solvent that forms a heteroazeotrope with water and can be easily separated into two layers from water is used. Examples of such solvents include chlorine solvents such as 1,2-dichloroethane and 1,2-dichloropropane, and hydrocarbon solvents such as cyclohexane, benzene and toluene.

The water introduced together with hydrogen peroxide and the water produced by the reaction can be removed by azeotropic distillation with a solvent that forms a heteroazeotrope with water, propylene, and if necessary an inert gas such as nitrogen gas. A concomitant dehydration method is used.

In order to proceed with the reaction efficiently, it is preferable to use commonly known acid catalysts, such as sulfuric acid, phosphoric acid, cation exchange resins, ortho- or meta-boric acid, and the like. These catalysts can be used alone or in combination. In order to suppress ring opening of the produced propylene oxide, a weak acid such as ortho or metaboric acid is preferred.

As the hydrogen peroxide and organic monocarboxylic acid used in the present invention, commercially available products can be used without any problem. Especially hydrogen peroxide is 30
~60% by weight aqueous solution is available as a commercial product and is preferred.
The amount of the organic monocarboxylic acid to be used is not particularly limited, but in order to react efficiently with hydrogen peroxide, it is desirable to use the organic monocarboxylic acid in an amount of 2 to 5 times the mole of hydrogen peroxide.

In addition, in order to react effectively with hydrogen peroxide, it is desirable to use propylene 1.5 to 10 times the mole of hydrogen peroxide, and for economic reasons, unreacted hydrogen peroxide and propylene should be recycled. It is preferable.

The produced propylene oxide is taken out of the reaction system from the upper part of the reactor together with water, solvent, unreacted propylene, or if necessary an inert gas such as nitrogen gas, and is separated and purified by a conventional method.

〔Example〕

The present invention will be explained in more detail with reference to Examples below. However, the present invention is not limited to the following examples.

Examples 1 to 5 A decomposition condenser and a 10-stage Oldagutz distillation column (inner diameter 3011+
1), and below it a multi-stage reaction tower made of Pyrex glass, inner diameter 50+ am, stage interval 120 mm, perforated plate porosity 1.5%, inner diameter 5++ m, 10-stage tray tower with overflow pipe, and as a bottom. A reactor consisting of a 1000 td Pyrex glass flask was used.

The residence time of the reaction liquid in the multistage reaction tower is determined by the height of the overflow tube of each stage (
It was designed to be adjustable by changing the weir height.

Propionic acid 168.7g/hr from the top of the multistage reaction tower
(2,'280 mol/hr), 1,2-dichloroethane 765.0 g/hr (7,727 mol/hr)
, 60% by weight hydrogen peroxide solution 43.1g/hr (0,76
0+*ol/hr), 3.0g of orthoboric acid as catalyst
/hr was heated to 70°C and charged.

On the other hand, 63.8g of propylene was extracted from the bottom of the reactor in gaseous form.
/hr (1,520mol/hr), nitrogen gas 1204! /hr, and the reactor bottom was heated to 70°C using an oil bath.

Propylene oxide, unreacted propylene, nitrogen, 1.
The gas phase containing 2-dichloroethane passes through a partial condensation condenser to the outside of the reaction system, and unreacted hydrogen peroxide, propionic acid,
The liquid phase containing the catalyst etc. was continuously extracted from the bottom of the reactor.

The overflow pipe height (weir height) of each stage of the multistage reaction tower was adjusted so that the residence time in the multistage reaction tower and the residence time at the bottom were as shown in Table 1.

Ten hours after the start of the reaction, the composition of the gas discharged from the partial condenser was analyzed by gas chromatography. The results of measuring the propylene oxide produced and the yield of propylene oxide are shown in Table 1.

Example-6 Propionic acid 168.7g/hr (2,280mol/
hr) instead of acetic acid 138.1g/hr(2,302
It was carried out in the same manner as in Example-1 except that mol/hr) was used.

Table 1 shows the measurement results of the propylene oxide produced and the propylene oxide yield.

Example-7 Propionic acid 168.7g/hr (2,280mol/
butyric acid 220.3g/hr (2,501
The procedure was carried out in the same manner as in Example-1, except that mol/hr) was used.

Table 1 shows the measurement results of the propylene oxide produced and the propylene oxide yield.

Comparative Example-1 Under normal pressure, propionic acid was added to the fifth stage from the top of a 1000 m Pyrex glass reactor equipped with a 30-stage Oldagout distillation column and equipped with a partial condensation condenser that circulated 40"C hot water at the top of the tower. 168.7g/hr (2,280111
ol/hr), 1,2-dichloroethane 765.0
g/hr (7,727 mol/hr)', 60 wt% hydrogen peroxide 43.1 g/hr (0,760 WAol/h
r) 3.0 g/hr of orthoboric acid was heated to 70° C. and charged as a catalyst.

On the other hand, 63.8g of propylene was extracted from the bottom of the reactor in gaseous form.
/hr (1,520wol/hr), nitrogen gas was charged at 120ffi/hr, and the reactor bottom was heated to 70°C using an oil bath. At this time, the residence time of the reaction liquid in the Orgusho distillation column was 10 minutes, and the residence time at the bottom was 80 minutes.
It was a minute.

Propylene oxide, unreacted propylene, nitrogen, 1.
The gas phase containing 2-dichloroethane passes through a partial condensation condenser to the outside of the reaction system, and unreacted hydrogen peroxide, propionic acid,
The liquid phase containing the catalyst etc. was continuously extracted from the bottom of the reactor.

Ten hours after starting the reaction, the composition of the gas coming out of the partial condenser was measured by gas chromatography.

Table 1 shows the measurement results of the propylene oxide produced and the propylene oxide yield.

〔Effect of the invention〕

As is clear from the examples, the present invention enables efficient direct production of propylene oxide from hydrogen peroxide and propylene, avoids concentration of percarboxylic acid, greatly improves safety, and enables miniaturization of equipment. Therefore, it is highly economical and has great industrial value.

Claims (1)

[Claims] 1. Forms a heteroazeotrope with water as a solvent, and
Hydrogen peroxide and propylene oxide When producing propylene oxide from propylene and hydrogen peroxide using an inert solvent and in the presence of an organic monocarboxylic acid, (1) A multistage reaction tower is used as the reaction tower. (2) A method for producing propylene oxide, characterized in that the water introduced into the reaction tower and the water produced by the reaction are continuously taken out from the upper part of the reaction tower together with the solvent and the produced propylene oxide. 2. The method according to claim 1, wherein the relationship between the residence time T_1 of the reaction liquid in the multistage reaction tower and the residence time T_2 of the reaction liquid at the bottom is expressed by the following equation. R=T_1/
(T_1+T_2), R≧0.2T_1: Reaction liquid residence time in the multistage reaction tower T_2: Reaction liquid residence time at the bottom 3 The organic monocarboxylic acid is acetic acid, propionic acid, butyric acid, or isobutyric acid. The method described in Section 1.