JPH049772B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for carrying out an organic reaction using a solid acid catalyst in a short period of time, at a high reaction rate, and moreover economically.

There are various types of solid acid catalysts, including silica/alumina compounds such as zeolites, heteropolyacids, and strongly acidic ion exchange resins, but with the exception of ion exchange resins, their activity is significantly lower when used in systems containing water. Most solid acid catalysts used in water-containing systems are mainly made of strongly acidic cation exchange resins, and Amberlite 1R-
120B, Amberlite 200C(H), Amberlist
15 is an example.

These ion exchange resins are usually spherical and have an effective diameter of
The particle size is approximately 0.4 to 0.7 mm, but smaller particles may be used, or they may be pulverized if necessary. If the particle size is small, the specific surface area will be large and the reaction rate will be faster; however, if the particle size is too small, the catalytic resistance with the liquid will increase, which is undesirable because it will cause operational inconvenience.

These organic reactions using solid acid catalysts include (1) a method in which a liquid phase reaction is carried out without distillation during the reaction in contact with a solid acid catalyst, and (2) a method in which the reaction is carried out in the presence of a solid acid catalyst. Among them, there is a method of performing a gas-liquid phase reaction accompanied by distillation. In the former reaction, contact between these solid acid catalysts and the reaction raw materials is usually carried out in a packed column or a stirring tank. It is customary to pressurize and liquefy the reaction raw material, which is a gas under standard conditions, and then react it in a packed column. In such a method, as mentioned earlier,
This is an extremely effective method that can increase the reaction rate by increasing the specific surface area, but it also has a fatal flaw.

In other words, after the reaction reaches an equilibrium state because unreacted raw materials and reaction products coexist in the reaction tank,
The reaction does not proceed any further.

For example, when a mixed solution of 1 mole of methyl acetate, 4 moles of water, and 0.4 moles of methanol is brought into contact with an ion exchange resin catalyst, the hydrolysis rate is approximately 55% when the reaction reaches equilibrium. Further, the amount of catalyst used is determined by the contact time with the reaction raw materials. In other words, the amount of catalyst used is proportional to the volume of reactant fluid that is contacted with the catalyst per unit time. If 100
Compared to if % hydrolysis were to occur, this example would require approximately twice the amount of catalyst and twice the size of the reactor.

Of course, it is possible to further increase the hydrolysis rate by adding an excess amount of water, which is a reaction raw material. For example, if you use 10 times the mole of water to methyl acetate, it will be approximately 75%
A hydrolysis rate of However, this not only increases the amount of catalyst used and increases the size of the reaction tank, but also requires a huge amount of energy to remove unreacted water from the system.
It's not practical at all.

The latter method, the so-called reactive distillation method, does not have such defects and can virtually carry out the reaction completely even if the reaction has an extremely small equilibrium constant. This method is a method in which a catalyst is packed into a distillation column and the product is taken out of the system while the reaction takes place. In the above example of hydrolysis of methyl acetate, the reaction product acetic acid has the highest boiling point, so as soon as it is produced, it is separated from the reaction section and flows down to the bottom of the column. On the other hand, since the reaction raw materials methyl acetate and water have lower boiling points than acetic acid, they remain in the reaction zone and further participate in the progress of the reaction. Therefore, if the reaction time is selected appropriately, a reaction rate of virtually 100% can be obtained.

However, this reactive distillation method also has some problems. In the reactive distillation method, at least one compound among the reaction raw materials and reaction products is in the gas phase, and at least one compound is in the liquid phase. The catalyst layer must be wet with this liquid and yet allow gas to easily pass through the catalyst layer. That is, as long as the operation of reactive distillation is performed, the catalyst packing density per unit volume must be low.

In a reaction that does not involve distillation, a dry weight of about 600 kg of catalyst can be packed per 1 m ³ , but in a reactive distillation column, the amount packed per 1 m ³ is usually only about 200 kg, which reduces the equipment cost of the reactive distillation column as a reaction tank. is incomparably higher than that in a reaction tank used in the liquid phase. In addition, such a low packing density inevitably lowers the contact efficiency between the reaction raw materials and the catalyst, so in the reactive distillation method, more catalysts are required, resulting in higher equipment costs.

Thus, one problem with the reactive distillation method using a solid acid catalyst is that the equipment cost is high. Therefore, although it has the great advantage of being able to obtain a high reaction rate, it is defeated by the drawback of high equipment costs, and its applications are limited.

Another problem is that it is nearly impossible to regenerate or reactivate the catalyst in reactive distillation methods.
There are various causes for catalyst activity reduction, and if it is due to irreversible chemical change or physical destruction of the catalyst, reactivation is impossible. If the function of the catalyst deteriorates, or if side reaction products contaminate the surface of the catalyst and prevent contact between the reaction raw materials and the catalyst, ion exchange treatment with mineral acid or cleaning with a solvent may be performed. In many cases, it is possible to restore activity.

The non-distillation reactor used in the former reaction method allows efficient contact with an aqueous mineral acid solution or solvent in the same reactor and, if necessary, the catalyst as a liquid slurry in another reactor. It can also be easily transferred to a container.

However, reactivation of the catalyst within the reactive distillation column cannot be carried out as easily. Here again, poor contact efficiency between the chemical solution for reactivation and the catalyst is a fatal problem. Although the work is not impossible, large amounts of chemical liquid must be repeatedly flowed down, and it is necessary to make the column material capable of withstanding this chemical liquid for reactivation, which is not the essential purpose of a reactive distillation column. It is. Furthermore, when packed in a distillation column, the shape of the catalyst is large (for example, a Raschig ring with a diameter of 25 mm) to ensure sufficient porosity, and therefore it is not easy to take it out of the column. Moreover, in order to remove the catalyst from the column, which is shaped like a block, large-scale operations such as removing the top of the column are required. As described above, since it is not easy to remove the catalyst from the column, it is virtually impossible to reactivate the catalyst inside the distillation column, although it is important to use the catalyst for a long period of time.

As mentioned above, the former method of reacting in a liquid phase in a packed tank or a stirred tank and the latter reactive distillation method each have favorable properties, but at the same time they also have drawbacks and are best when used alone. It is difficult to say that this is a means of reaction.

The present invention has succeeded in skillfully combining both of these methods, thereby bringing out only their respective strengths and compensating for each other's deficiencies, thereby allowing an extremely economical organic reaction to occur.

The gist of the present invention is that in an organic reaction using a solid acid catalyst, first, all or a part of the reaction raw materials are subjected to a liquid phase reaction without distillation during the reaction under the catalysis of a solid acid catalyst, and then The reaction raw material that has undergone this liquid phase reaction is subjected to a gas-liquid phase reaction accompanied by distillation in the presence of a solid catalyst, and if there is any remaining reaction raw material, it is transferred to the subsequent gas. This is an organic reaction method characterized by countercurrent contact in a liquid phase reaction, and organic reactions to which the present invention can be applied include esterification reactions, hydration reactions, and hydrolysis reactions. .

In addition, solid acid catalysts used in liquid phase reactions that do not involve distillation during the reaction are spherical or crushed strong acid cation exchange resins with a particle size of 1 mm or less, or
Strongly acidic cation exchange fibers of 100μ or less are preferred;
On the other hand, as a solid acid catalyst used in a gas-liquid phase reaction involving distillation during the reaction, strongly acidic cation exchange fibers with a diameter of 100 μm or less are desirable.

Examples of strongly acidic cation exchange fibers include those obtained by impregnating polypropylene fibers with styrene monomers and divinylbenzene monomers in the presence of a swelling agent, polymerizing them, and then sulfonating them, and those obtained by graft polymerizing styrene and divinylbenzene onto the fibers. Sulfonated products, polyvinyl fibers that are heat-treated and partially carbonized and then sulfonated, monomers with sulfon groups, such as vinyl sulfonic acid and styrene sulfonic acid, copolymerized with other monomers. A fibrous material can be used.

Hereinafter, the method of the present invention will be specifically explained using the hydrolysis of methyl acetate as an example. Since the method of the present invention is based on the premise that reactive distillation is also used, the raw material can be sent to the reaction process assuming a hydrolysis rate of 98%. In the case of a reaction that does not involve distillation, in order to obtain 100 moles of acetic acid as a result, the reaction rate is 55%, so approximately 180 moles of methyl acetate and 720 moles of water must be supplied. It is necessary to separate 80 moles of unreacted ester and 620 moles of water by means such as distillation and extraction and recycle them. On the other hand, when the reactive distillation of the present invention is used in combination, the feedstocks may be 102 moles of methyl acetate and 408 moles of water.

Therefore, when using reactive distillation in combination as in the present invention, even if the amount of catalyst used in the reaction without distillation in the first stage is reduced to about half the amount, the hydrolysis will not change, and moreover, the catalyst will deteriorate the function of the catalyst. Poisons are captured here and are not sent to the subsequent reactive distillation column.

The reactive distillation column that performs the subsequent reaction consists of a reaction section filled with a catalyst and a rectification section not filled with a catalyst.
In the hydrolysis of esters, the lower half of the column is used as a rectification section and the upper half is used as a reaction section. In the hydrolysis of methyl acetate, the stock solution to be treated is fed to the bottom end of the reaction section, ie, the top end of the rectification section.

When the liquid that was 55% hydrolyzed in the previous reaction tank, that is, a mixed solution of 46 moles of unreacted methyl acetate, 56 moles of acetic acid, 56 moles of methanol, and 352 moles of water, is supplied to the reactive distillation column. Acetic acid, which has a high boiling point, flows directly to the bottom of the column via the rectification section and does not enter the reaction section.

In other words, this is equivalent to supplying a mixed solution of 46 moles of methyl acetate, 56 moles of methanol, and 352 moles of water to the reactive distillation column. The advantage of using a reaction that does not involve distillation in the first stage, compared to the case where all reactions are carried out only by reactive distillation, is not only that the load is reduced, but also that it is important to adjust the molar ratio of methyl acetate and water. It's in the function. In the example above this ratio is 46
The ratio is 352, or 1:7.7. As mentioned earlier, the larger the ratio, the higher the hydrolysis rate, but it also increases the reaction rate, which reduces the size of the reactive distillation column that performs the subsequent reaction, resulting in a significant savings in equipment costs. .

In the case of esterification, in contrast to hydrolysis, the resulting liquid is partially reacted in the liquid phase and is supplied to the upper part of the reaction section of the reactive distillation column. The ester that has already been produced is immediately discharged from the top of the column, and the reaction proceeds while unreacted acid and alcohol flow down the reaction section.

In this way, a part of the organic reaction is first brought to a stage close to equilibrium in the liquid phase through a reaction that does not involve distillation in the first stage, and then the reaction rate is increased through a reactive distillation reaction that involves distillation in the second stage. The method of the present invention, which further increases the reaction value, is an extremely effective and novel reaction method. However, in carrying out the present invention, it is not necessary to treat all of the raw materials in a liquid phase without distillation in the first stage, and to supply the treated liquid as it is to a reactive distillation column where a reaction involving distillation in the second stage is carried out. There are no restrictions. In some cases, it may be advantageous to implement the method with some modifications. This includes cases where there is a large difference in boiling point between the raw materials involved in the reaction, such as acid and alcohol in esterification, ester and water in ester hydrolysis, etc.
In the hydration of olefin, there is olefin and water.

To be more specific, in the hydrolysis of methyl acetate, when a mixture of water and methyl acetate as reaction raw materials is supplied to the bottom of the reaction section of a reactive distillation column, methyl acetate, which has a low boiling point, easily rises up the reaction section. On the other hand, some of the water, along with the reaction product acetic acid,
It flows down to the bottom of the tower without reaching the reaction section.
In the production of ethyl acetate, acetic acid supplied to the top of the reaction section flows down the reaction section, but a large proportion of ethyl alcohol exits from the top of the column together with ethyl acetate. Since ethyl alcohol and ethyl acetate form an azeotrope with the lowest boiling point, the loss is even greater. In this way, there are multiple reaction raw materials,
Moreover, when the difference in their boiling points is large, it is preferable to feed the high-boiling raw material from the upper part of the reaction section of the reactive distillation column and the low-boiling raw material from the lower part, and to bring them into countercurrent contact in the reaction part.

On the other hand, in esterification and ester hydrolysis, when feeding raw materials directly to a reactive distillation column without performing a preliminary reaction in the liquid phase, rather than feeding two raw materials together, they are placed in the upper and lower parts of the reaction section. The reaction efficiency is higher when supplied from both ends.
In other words, the processing capacity of the equipment will increase.

However, this is still not as good as the method of the present invention in which the liquid resulting from the preliminary reaction in the liquid phase is supplied from one place. In order to obtain the best results both functionally and economically, one part of the raw materials is separated when carrying out the process of the invention, and the remaining raw material mixture is distilled into a liquid phase without a previous distillation step. After reacting in the reaction section of the reactive distillation column, it is sent to the reactive distillation column that carries out the subsequent distillation for reaction. Obtained when supplied from

For example, in the case of hydrolyzing methyl acetate, a mixture of 1 mole of methyl acetate and 3 moles of water is supplied to a column packed with a strongly acidic cation exchange resin, and the reaction is brought to almost equilibrium. 1 per mole of methyl acetate.
A molar equivalent of water is supplied to the upper part of the reaction section.

Although the optimum proportion ratio of raw materials differs depending on the type of reaction, it is desirable that at least the so-called stoichiometric amount of raw materials, assuming that the reaction is carried out ideally, be subjected to the preliminary reaction in the liquid phase.

Examples will be described below.

Comparative example 1 1 mol of methyl acetate, 4 mol of water, 0.4 methanol
Amberlite 1R-124 200 which was adjusted to H type after making a mixed solution with a molar ratio and heating it to 60℃
The liquid was passed through a column with an inner diameter of 25 mm filled with 1.0 mL of the solution in an upward flow. The results are shown in Table 1. SV in the table is per hour.
Indicates how many times the liquid was processed compared to the Amberlite 1R-124 filling volume.

S V Hydrolysis rate 0.5 55% 1.0 55% 1.5 49% To obtain 1 mol of acetic anhydride, it was necessary to separate 0.82 mol of methyl acetate and 6.27 mol of water.

Comparative Example 2 A glass helix with a diameter of 4 mm was filled up to a height of 800 mm at the bottom of a distillation column with an inner diameter of 25 mm to form a rectification section, and a single fiber made of ion exchange fiber IONEX manufactured by Toray Industries, Inc. was filled up to a height of 400 mm above the column. A cylindrical catalyst with a length of 4 mm wound spirally with a diameter of 4 mm was filled in a cloth-like material having a thickness of 20 μm to form a reaction section. The reaction section volume is 200ml.

A mixed solution containing 1 mole of methyl acetate and 0.4 mole of methanol was supplied from the bottom of the reaction section, and water equivalent to 4 moles of methyl acetate was supplied from the top of the reaction section, and the reactor was operated under pre-reflux. All raw material liquids were heated to 60℃,
While keeping the molar ratio of methyl acetate, methanol, and water constant, the amount of liquid supplied is adjusted to maintain the hydrolysis rate.
Results of calculating the total amount of supplied liquid when reaching 95% 1
It was 72 ml per hour.

Example 1 Using the same experimental equipment as in Comparative Example 2, the liquid obtained when SV was 1 in Comparative Example 1 was supplied to the lower end of the reaction, and as in Comparative Example 2, a hydrolysis rate of 95% was obtained. The maximum throughput was determined. The amount of treated liquid per hour was 110 ml.

Example 2 In the same manner as in Comparative Example 1, a mixture of 1 mol of methyl acetate, 2 mol of water, and 0.4 mol of methanol was prepared.
Processed with SV1. The hydrolysis rate was 41%.

This liquid was supplied to the lower end of the reaction section of the experimental equipment of Comparative Example 2, and at the same time, water equivalent to 2 moles of methyl acetate was added to the top of the reaction section. The maximum total liquid volume when a hydrolysis rate of 95% was obtained was 180 ml per hour.

Claims (1)

[Claims] 1. In an organic reaction using a solid acid catalyst, the reaction raw material is first brought into contact with the solid acid catalyst to undergo a liquid phase reaction without distillation during the reaction, and then subjected to this liquid phase reaction. An organic reaction method characterized by subjecting reaction raw materials to a gas-liquid phase reaction accompanied by distillation during the reaction in the presence of a solid acid catalyst. 2 A part of the reaction raw material undergoes the liquid phase reaction in the first stage, then the gas-liquid phase reaction in the latter stage, and the remaining part of the reaction raw material is directly subjected to the gas-liquid phase reaction in the latter stage, and both are countercurrently reacted in the latter stage gas-liquid phase reaction. Claim 1 to be brought into contact
Organic reaction method described in section. 3. The organic reaction method according to claim 1 or 2, wherein the organic reaction is an esterification reaction, a hydration reaction, or a hydrolysis reaction. 4 Claims in which the solid acid catalyst used in a liquid phase reaction that does not involve distillation during the reaction is a spherical or crushed strongly acidic cation exchange resin with a particle size of 1 mm or less or a strongly acidic cation exchange fiber with a diameter of 100 μ or less The organic reaction method according to any one of items 1 to 3. 5. The solid acid catalyst according to any one of claims 1 to 4, wherein the solid acid catalyst used in the gas-liquid phase reaction that involves distillation during the reaction is a strongly acidic cation exchange fiber with a diameter of 100 μm or less. Organic reaction methods.