JPH07116083B2 - Method for producing allyl alcohol - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing allyl alcohol.

More specifically, the content of particles with a particle size of 1 μm or less is 3%
The present invention relates to a production method characterized in that allyl alcohol is produced by isomerizing propylene oxide in the presence of a catalyst obtained by suspending propylene oxide in a high boiling point solvent using the following lithium phosphate as a catalyst.

[Conventional technology]

It is known to produce allyl alcohol by the isomerization of propylene oxide in the presence of a catalyst.

Lithium phosphate is commonly used as a catalyst from the viewpoint of activity.

[Problems to be solved by the invention]

It is known to produce allyl alcohol by suspending a catalyst in a high boiling organic solvent using a lithium phosphate catalyst, continuously charging propylene oxide at a temperature of 200 ° C. or higher, and isomerizing propylene oxide. is there.

For example, according to JP-B-39-10313, the particle size can be
Allyl alcohol is obtained by suspending 0.1 to 250 mμ of lithium phosphate and isomerizing propylene oxide.

When industrialized by this method, propylene oxide is continuously supplied to continuously obtain allyl alcohol.

In this case, since the catalyst is contaminated by the propylene oxide polymer, etc., the high boiling point solvent in which the catalyst is suspended is partially withdrawn from the system, separated into the catalyst and the solvent, and the catalyst is washed with an appropriate solvent. In this method, the polymer contained in the catalyst is removed and then the catalyst is returned to the reaction system.

In this case, if the content of the catalyst particles is small, but the content is large, the amount of the catalyst flowing out of the system is large during the operation of separating the catalyst from the high boiling point solvent and washing the catalyst with the solvent, and the catalyst concentration during the reaction is kept constant. It has been found that there is a serious drawback in that a large amount of catalyst has to be supplied.

The present inventor provides a method for industrially producing allyl alcohol by isomerization of propylene oxide.

[Means for solving problems]

The present inventor, as a result of extensive studies on a method for industrially advantageously producing allyl alcohol by isomerizing propylene oxide to achieve the above object, found that the distribution of the catalyst particle size is an important factor, Completed the invention.

The present invention provides an economically advantageous method for producing allyl alcohol by controlling the catalyst particle size.

That is, the present invention relates to "in the production of allyl alcohol by isomerization of propylene oxide, lithium phosphate having a particle size of 1 μm or less and a content of 3% or less is used as a catalyst, and the catalyst is an organic solvent having a boiling point of 200 ° C. or more. Suspended in, 200
A method for producing allyl alcohol from propylene oxide, characterized in that propylene oxide is isomerized at a temperature of ℃ or more. "

In a suspension of a lithium phosphate catalyst used in the present invention and a high boiling point solvent, the catalyst tends to precipitate during the reaction when the particles of the lithium phosphate as a catalyst are too large, and the reaction rate of propylene oxide decreases. Have.

On the other hand, if the catalyst particle size is small, there is an advantage that the homogeneity with the high boiling point solvent is improved, but a part of the suspension is used for the purpose of removing the polymer generated during the reaction which becomes the catalyst poisoning component. The catalyst loss cannot be ignored in the process of extracting the catalyst out of the system, separating the catalyst from the high boiling point solvent, washing the catalyst containing the polymer and the like with an appropriate solvent, and regenerating the catalyst.

It is expected that the catalyst particle size is an important factor for suppressing the activity, suspension property and loss of the catalyst during the regeneration process.

If the diameter of the catalyst of the present invention is too small, the loss is increased, and if the diameter is too large, the activity is lowered and the suspending property is lowered. Therefore, the average particle diameter of the catalyst is in the range of 3 to 20 μm. 70% or more of particles having a particle size of 1 to 10 μm are contained, and the point of the present invention is to use a catalyst having a particle size distribution of 3% or less for particles having a particle size of 1 μm or less.

It is desirable to select a high-boiling solvent used for suspending the catalyst so as to dissolve well the polymerized substance which is a catalyst poisoning component produced during the reaction step.

This is because the polymerized substance generated during the reaction is eluted from the catalyst by the solvent to suppress the decrease in the activity of the catalyst.

The boiling point of the solvent should be at least above the temperature at which isomerization occurs.

As a solvent satisfying these requirements, there are aromatic or alicyclic hydrocarbons, and specific examples thereof include alkylbenzene, arylbenzene, and a partially or wholly hydrogenated terphenyl compound.

As the catalyst used in the present invention, a general method for producing lithium phosphate is adopted.

For example, it can be produced from an aqueous solution of orthophosphoric acid and an aqueous solution of lithium hydroxide, or can be produced from an aqueous solution of trisodium phosphate and an aqueous solution of lithium hydroxide.

The particle size distribution of lithium phosphate depends on the concentration of raw materials used, the molar ratio, and the mixing state. Generally, when the salt concentration becomes low, the particles become coarse, and when the ratio of lithium and phosphorus becomes small, the particles become coarse.

The method of mixing the raw materials is also an important factor for adjusting the particle size of the catalyst.

As a concrete mixing method, a method of pouring another raw material into one solution, or a co-pouring method of pouring at the same time coarsens the particles, and the slower the co-injection acceleration is, the coarser the particles become.

In carrying out the present invention, the proportion of the high-boiling solvent and the catalyst can be arbitrarily determined, but if the proportion of the catalyst is too small, the rate of change of the raw material propylene oxide is poor, and conversely, if the proportion of the catalyst is large, the suspension It is not desirable because it loses fluidity,
The catalyst concentration is 3 to 30%, preferably 10 to 25%.

When the concentration of the catalyst in the suspension becomes high, the fluidity disappears,
The propylene oxide that is blown in the form of gas becomes fine particles and is prevented from passing through the suspension.

This suspension is maintained at an appropriate temperature, propylene oxide is introduced, and the produced allyl alcohol-based vapor is condensed.

Generally, the raw material propylene oxide is preheated to the reaction temperature and introduced into the reactor, and the reaction heat is removed from the outside, or the propylene oxide preheat is made lower than the reaction temperature and then introduced into the reactor. The heat of reaction can be removed.

The reaction temperature is preferably 200 ° C to 350 ° C.

The boiling point of the high boiling point solvent used to disperse the catalyst is preferably higher than the reaction temperature.

As a high boiling point solvent, of course, it is necessary that it has no chemical effect on propylene oxide and allyl alcohol and is stable at the reaction temperature.

The contact time between the propylene oxide and the catalyst suspension can be varied over a wide range depending on the production conditions, but is generally about 1 to 100 seconds, preferably about 3 to 20 seconds.

The reaction pressure can be atmospheric pressure or under pressure, but it is necessary to carry out the reaction at a pressure lower than the vapor pressure of allyl alcohol at the reaction temperature, generally 1 to 25 atm, preferably 1 to 8 atm. Good to do in.

A method for implementing the present invention will be specifically described with reference to FIG.

Allyl alcohol and unreacted propylene oxide charged by the raw material propylene oxide charging device 1-1 into the propylene oxide isomerization reactor 2-2 and reacted are the propylene oxide and allyl alcohol provided in the upper part of the reactor 2-2. After separation from the high boiling point solvent accompanied by the alcohol distilling tower 3-3, purified allylic alcohol is obtained by the raw propylene oxide recovery tower and the allyl alcohol production tower through the piping of the propylene oxide and allyl alcohol recovery system line 4-4.

5-5 is a heat medium extraction line.

The reactor 2-2 is provided with a stirrer 6-6, and the catalyst suspension is preferably stirred in order to improve the homogeneity in the reactor.

A part of the high boiling point solvent in which the catalyst is suspended is withdrawn from the reactor 2-2, introduced into the mixing tank 8-8, and the catalyst cleaning liquid is added from the catalyst cleaning liquid charging tank 9-9 while stirring with the stirrer 7-7. The polymerized substance deposited on the catalyst is dissolved, and the catalyst is separated from the high boiling point solvent and the catalyst washing liquid by the catalyst separator 11-11 through the catalyst extraction line 10-10.

If necessary, a catalyst cleaning liquid can be further added from the catalyst cleaning liquid charging line 12-12 to clean the catalyst.

13-13 is a catalyst extraction line.

The washed catalyst is charged with a high boiling point solvent from the catalyst preparation tank 14-14 through the high boiling point solvent charging line 16-16, and the catalyst is suspended and returned to the reactor 2-2.

In this case, if necessary, a new catalyst may be added from the new catalyst charging line 15-15.

The cleaning liquid and high boiling point solvent separated in 11-11 are sent to the cleaning liquid and high boiling point solvent recovery system from the line 17-17, and the cleaning liquid and high boiling point solvent are purified by distillation and reused.

Next, the present invention will be described more specifically by way of examples.

Example 1 [Preparation of catalyst] A solution prepared by dissolving 278 parts of trisodium phosphate in 1000 parts of water is heated to 70 ° C.

A solution prepared by dissolving 90 parts of lithium hydroxide and 28 parts of sodium hydroxide in 680 parts of water is heated to 70 ° C. and vigorously stirred.

The whole amount of the solution is poured into the solution at a constant rate for 90 seconds.

The resulting precipitate was filtered, washed and dried at 110 ° C to obtain a catalyst.

The particle size distribution of the catalyst was measured by the Andreazen method, and 2.4% of the total particles had a particle size of 1 μm or less, 2.6 μm for 1-2 μm, 4.2% for 2-3 μm, and 3-5 μm.
Was 9.2%, 5-10 μm was 49.3%, and 10-20 μm was 32.2%.

[Reaction] 4.5 parts of the above catalyst was used for Therm S900 (manufactured by Nippon Steel Chemical Co., Ltd .: hydrogenated triphenyl initial boiling point 332 ° C dry point 3
(78 ° C), and propylene oxide was fed at a reaction temperature of 270 ° C at 5.6 parts per hour.

0.0036 parts of the suspension containing the catalyst was continuously withdrawn every day, washed with acetone, and then the catalyst and the heating medium were separated.

New catalyst is continuously added to the separated catalyst at a rate of 0.004 parts every day.

Mix the same amount of THERM S900 extracted into this catalyst and return to the reactor.

This operation was continuously performed for 2 weeks.

The allyl alcohol concentration in the reaction product solution distilled from the reactor remained constant at 35.9% for 2 weeks.

After the reaction, the catalyst concentration in the suspension remained at the initial 15%.

Comparative Example 1 [Preparation of catalyst] A catalyst was prepared in the same manner as in Example 1 except that the time for pouring the solution into the solution was changed to 70 seconds.

The particle size distribution of the obtained catalyst is as follows.

20 to 10 μm 11.1% to 5 μm 48.8 to 3 μm 16.3 to 2 μm 8.8 to 1 μm 6.5 1 μm or less 7.6 [Reaction] The reaction was conducted in the same manner as in Example 1 and the results were as follows.

Day 1 of reaction start Allyl alcohol concentration in reaction solution 36.5% 7th day 〃 33.4% 14th day 〃 31.7% Allyl alcohol yield decreased over time, 14
The catalyst concentration on the day dropped to 11.1%.

[Brief description of drawings]

FIG. 1 is a block diagram of a reaction apparatus used for carrying out the method of the present invention, 2-2 is a propylene oxide isomerization reactor, and 11-11 is a catalyst separation tank.

Claims (1)

[Claims] 1. In the production of allyl alcohol by isomerization of propylene oxide, lithium phosphate having a particle size of 1 μm or less and a content of 3% or less is used as a catalyst, and the catalyst is in an organic solvent having a boiling point of 200 ° C. or more. A process for producing allyl alcohol from propylene oxide, which comprises suspending in propylene oxide and isomerizing propylene oxide at a temperature of 200 ° C. or higher.