JPH0356134A - Reactive distillation apparatus - Google Patents

Abstract

PURPOSE:To increase the concn. of a reaction product in a vapor phase by recirculating a solution containing a reactive substance and the reaction product in a reactor packed with a solid acid or base catalyst and bringing the vapor of a reaction solution subjected to solid-liquid contact into gas-liquid contact with a liquid subjected to solid-liquid contact. CONSTITUTION:A liquid containing a reactive substances bringing about reaction equilibrium of two or more components and a solid acid catalyst (e.g., cation exchange resin) or a solid base catalyst (e.g., K supported activated carbon) are subjected to solid-liquid contact and components rich in one component of reaction products accompanied by reaction equilibrium is obtained as distillate components. At this time, a plurality of reactors A - C packed with the solid acid or base catalyst are provided. In one or more reactor among them, a liquid containing two or more reactive substances and two or more reaction products is recirculated and the vapor of the reaction liquid subjected to solid- liquid contact in at least one reactor is forcibly recirculated in the other reactor to be subjected to solid-liquid contact and subjected to the gas-liquid contact with a liquid containing the reactive substances and the reaction products to increase the concn. of one component of the reaction products in a vapor phase.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a system in which a reactive substance with a reaction equilibrium of two or more components is used as a raw material to produce a reaction product with a reaction equilibrium of two or more components. This invention relates to an efficient apparatus for reactive distillation when the reaction involves reaction equilibrium. More specifically, the present invention relates to a reactive distillation apparatus using a solid acid or a solid base.

(Prior Art) The use of sulfuric acid or sodium hydroxide in equilibrium reactions using acidic or basic catalysts is well known.

An example is the reaction of methanol and acetic acid to produce methyl acetate and water.

Sulfuric acid is used when the reaction proceeds advantageously under acidic catalysis, and sodium hydroxide is used when the reaction proceeds under basic catalysis.

However, in the case of sulfuric acid, it causes corrosion of metal materials, and in the case of sodium hydroxide, it is troublesome to separate the reaction product from other components.

Another typical example is the formation of methylal and water by the reaction of methanol and formaldehyde (or formalin).

Methyral is synthesized by a condensation reaction of methanol and formaldehyde in the presence of an acidic catalyst.

2C}130}1 + cuzo −+ C
As a method for combining HxOCHzOCHi + HzO methylal, for example, Solvent Handbook (Kodansha Publishing, 1976) discloses the use of an acidic catalyst such as zinc chloride, ferric chloride, or hydrochloric acid.

The reaction of synthesizing methylal from methanol and formaldehyde is an equilibrium reaction that produces water as a by-product, so there are limitations to improving the reaction yield.

In order to solve these problems, the special public
Publication No. 5 discloses that a raw material mixture of methanol and formalin aqueous solution is pre-acetalized using a cation exchanger, and a part of the liquid flowing out from the reactor using the cation exchanger is used to supply the raw material mixture. It is proposed that the water be resupplied from above.

Although this method has an excellent feature in increasing the reaction yield, it has the following problems in industrial implementation.

When ion exchange resin is used for a long period of time, its shape changes from granular to fine powder, disintegrates, and metal ions form. There is a problem that the catalytic activity decreases or disappears due to substitution of organic substances, accumulation of organic substances in pores, or elimination of sulfonic acid groups. The method in this publication proposes a method in which the cation exchanger is packed into the distillation column, so whenever the catalytic ability decreases, the production of methylal is stopped and the cation exchanger is taken out from the distillation column. , regeneration, catalyst replenishment, etc. must be performed. Therefore, the industrial implementation of this method has had complicated problems.

On the other hand, JP-A-56-147739 recommends the use of paraformaldehyde in order to increase the reaction yield. Also, regarding methanol, the chemistry of the reaction N? Although the molar ratio of a is 2, it is mentioned that it is necessary to use more than that. However, this method has disadvantages in industrial implementation, such as the use of paraformaldehyde and the reaction yield, which is at most 90% based on formaldehyde.

(Problems to be Solved by the Invention) The present invention uses a reactive substance (hereinafter referred to as "reactive substance") with reaction equilibrium of two or more components as a raw material to produce a reaction product (hereinafter referred to as "reactive substance") with reaction equilibrium of two or more components. The present invention provides an efficient reactive distillation apparatus that does not have the problems of the prior art when performing reactive distillation in a system in which reaction products (referred to as reaction products) are produced and the reaction involves reaction equilibrium.

(A Thousand Steps to Solving the Problem) As a result of intensive studies to solve the above problem, the present inventors discovered the usefulness of solid acids and solid bases, and found that solid acids and solid bases are useful when reaction equilibrium is involved. A general reactive distillation apparatus using a solid base was developed.

That is, the present invention brings a liquid containing two or more reactive substances into solid-liquid contact with a solid acid or solid base catalyst to obtain a component enriched in one component of a reaction product of two or more components as a distillate component. The apparatus comprises at least two reactors filled with a solid acid or solid base catalyst, at least one of which has a 2rv. A liquid containing a reactive substance and a reaction product of two or more components is forcibly circulated, and the vapor of the reaction liquid that has come into solid-liquid contact in at least one reactor is forcibly circulated in another reactor. The liquid containing the reactive substance and the reaction product after being circulated and brought into solid-liquid contact is brought into gas-liquid contact to increase the concentration of one component of the reactant in the vapor phase. This is a reactive distillation device.

When a solid base is used, the reactions performed by the reactive distillation apparatus of the present invention include, for example, benzene hydrodimerization reaction,
Examples include reactions in which a corresponding α,β monounsaturated compound is produced by reacting methanol with a ketone or a nitrile.

In the hydrodimerization reaction of benzene, solid bases that can be used at this time include, for example, potassium supported on activated carbon or alumina. In the reaction that produces β-unsaturated compounds, for example, Fe”,
Examples include those to which several percent of Cr3'' is added.

Next, reactions using solid acids include, for example, acetal production or its reverse reaction to obtain acetal from alcohol and aldehyde, esterification reaction to obtain ester from acid and alcohol or its reverse reaction, and ether to obtain ether from alcohol. Examples include etherification reaction, hydrocarbon isomerization reaction, and the like.

Examples of reactions include the reaction to obtain methylal from methanol and formaldehyde (hereinafter referred to as methylal production reaction), the reaction to obtain formaldehyde and methanol from dioxymethylene dimethyl ether and water, and the reaction between methacrylic acid and ethanol? These include a reaction to obtain ethyl taacrylate, a reaction to obtain acetic acid and butanol from butyl acetate and water, a reaction to obtain t-butyl methyl ether from t-butyl alcohol and methanol, and a reaction to obtain isobencune from pentane.

Solid acid catalysts used in these reactions include, for example, cation exchange resins, fluorinated alkylene resin sulfonic acid group derivatives, crystalline aluminosilicate, zeolite, Ti
Examples include O■-Sing.

As the cation exchange resin, both carboxylic acid group derivatives and sulfone Ha derivatives can be used, but sulfonic acid group derivatives are preferred in terms of high reaction yield.

Further, as the type of ion exchange resin, either a gel type cation exchange resin or a giant network cation exchange resin can be used, but the giant network cation exchange resin is preferable because it has a high reaction yield. Specific examples of ion exchange resins include styrene-divinylbenzene copolymer, acrylic acid-
Examples include divinylbenzene copolymer, methacrylic acid-divinylbenzene copolymer, and the like.

As the fluorinated alkylene resin sulfonic acid group derivative, a tetraethylene resin sulfonic acid group derivative (trade name: Nafion H) is preferable.

As crystalline aluminosilicate, Japanese Patent Publication No. 62-41
The molar ratio of silica to alkali as shown in Publication No. 656 is 1
0 or more are used.

In the present invention, a reactor filled with a solid acid or a solid base is a reactor in which a solid acid or a solid base exists, in which a liquid containing a reactive substance comes into solid-liquid contact, and the concentration of the reaction product is increased. It may be of any shape as long as it contains one ingredient. For example, a tank or tower tightly packed with solid acid or solid base, a tank or tower with solid acid or solid base dispersed in a slurry, or a tank or tower with loosely packed solid acid or solid base. An example is a tower. A feature of the present invention is that a liquid containing reactive substances and reaction products is forcibly circulated through the reactor.

A reactor containing a solid acid or a solid base used in the present invention, a reactive substance in solid-liquid contact with the solid acid, a liquid containing reacted raw materials, and a vapor containing a component with an increased concentration among the reaction products. There are no particular restrictions on the mode of gas-liquid contact with.

For example, the gas-liquid contact can be carried out using a plate column such as a bubble cap tray or a Scheeptreber-Zuffle tray, or a packed column using a filler such as Raschig ring, Dixon backing, or Goodroll packing.

The present invention consists of at least two reactors filled with a solid acid or solid base capable of forcibly circulating a liquid containing reactive substances and reaction products, and the reaction liquid obtained from the plurality of reactors is continuously It is designed to be distilled by contacting the gas with liquid.

For example, a preferred device includes a device in which a reactor filled with a solid acid or a solid base is connected to a distillation column.

A specific example is a device as shown in FIG. In FIG. 1, A. B and C are reactors filled with a solid acid or a solid base, respectively, and the liquid extracted from the middle stage of distillation column E is forcibly circulated in the reactor, reacted, and returned to the bottom of the distillation column. The reaction solution is brought into contact with gas and liquid in the distillation column E and distilled.

The larger the number of reactors, the higher the reaction efficiency, which is effective for increasing the reaction rate. However, if the number of reactors is too large, equipment costs will increase, which is not preferable.

The preferred number of reactors is 3 to 10, more preferably 3 to 10.
There are 5 pieces.

The position of extraction from the distillation column to the reactor and the position of return of the reaction liquid to the distillation column are not particularly limited and can be arbitrarily selected. It is preferable to determine the optimum position based on the composition of the reaction liquid.

The manner in which the reactive substance is supplied in the present invention can be arbitrarily determined depending on the boiling points of the reaction product and the reactive substance, and is not particularly limited. In one embodiment, when the boiling point difference between the reaction product and the reactive substance is large, for example, in the methylal biochemical reaction, methanol is supplied to the reactor connected to the distillation column closest to the top of the column, and forced circulation is performed. , formalin is supplied from this reactor to the upper stage. Another embodiment is to feed formaldehyde and methanol to the reactor closest to the top of the column, and to separately feed an aqueous solution containing formaldehyde to a feed stage above the reactor so that the methylal and methanol rise in the distillation column. contact with vapor containing vapor. At this time, the liquid in the reactor closest to the top of the column may or may not be forcedly circulated. When forced circulation is not performed, forced circulation is performed in a reactor connected to a distillation column located below this reactor in order to increase the efficiency of the reaction.

In another embodiment, when the boiling point difference between the reaction product and the reactive substance is small, for example, in an esterification reaction to obtain methyl acetate from acetic acid and methanol, methanol is added to the reactor connected to the distillation column closest to the top of the column. Acetic acid is supplied to the upper stage from this reactor through forced circulation. In order to increase the efficiency of the reaction, methanol is supplied to a reactor connected to a distillation column below this reactor, and forced circulation is performed. An example of the methylal synthesis reaction will be explained with reference to FIG.

In FIG. 1, a formalin aqueous solution and methanol are fed as raw materials to a distillation column via feed pipes 1 and 2, respectively. Three reactors ASB,C filled with solid acid
A liquid containing methanol, formaldehyde, methylal, and water is forcibly circulated inside.

The vapor consisting of the liquid that has come into solid-liquid contact in reactor B is transferred to reactor A.
Solid-liquid contact is made in the distillation column, and the liquid containing methylal is brought into gas-liquid contact in the distillation column. Methylal, a reaction product, is discharged from the top 3 of the column, and unreacted methanol, formaldehyde, and water, a by-product, are discharged from the bottom 4 of the column. In the present invention, as the formaldehyde raw material, for example, an aqueous formalin solution, trioxane, paraformaldehyde, etc. can be used, but an aqueous formalin solution is preferable from the viewpoint of handling and economy.

The methanol used is usually in a reaction stoichiometric ratio of 1 to 2 to formaldehyde. Used at 0 times or more. It is preferable to use methanol in a stoichiometric ratio of 1.0 to 1.2 times, particularly 1.0 to 1.1 times, relative to formaldehyde. Here, as a distillate, methylal ~
When obtaining a methanol azeotrope (92% methylal, 8% methanol), the stoichiometric ratio is 1.1 times, when only methylal is obtained, it is 1.0 times, and when obtaining something in between, it is 1. It is used at 0 to 1.1 times.

In addition, methylal to methanol forms an azeotropic component (92% methylal, 8% methanol). In order to obtain 95% or more methylal, especially 98% or more methylal, the raw material formalin aqueous solution is supplied from above the reactor connected to the distillation column, and the vapor and gaseous liquid containing methylal and methanol rise inside the distillation column. It has been found that upon contacting, the desired methylal is obtained.

The formalin aqueous solution as a raw material for methylal synthesis may contain trioxane.

(Examples) Examples in which reactive distillation is carried out using the reactive distillation apparatus of the present invention will be described below, but the present invention is not limited to the scope of these examples.

Example 1 The reactive distillation column shown in FIG. 1 was used. The number of reactors is 3
It is the basis. Each of the reactors A, B, and C was filled with a giant reticulated strongly acidic cation exchange resin (trade name: Amberlite 2).
Fill 150cc of 00C). Feed tubes 1 and 2
300g of 40% formalin aqueous solution per hour.
, 283 g of methanol was supplied per hour.

As the distillation column E, a packed column with a column height of 1.5 m was used.

A stage was provided in the middle of distillation column E to extract liquid components, and the liquid components were circulated to reactors ASB and C using pumps to bring them into solid-liquid contact with the catalyst. The methylal-containing reaction liquids leaving reactors A, B, and C are returned to the distillation column, where they come into gas-liquid contact with the vapor coming from the bottom of the distillation column toward the top, increasing the concentration of methylal. . The reflux liquid was returned to maintain the top temperature at 42°C. 32 per hour from tower top 3
7 g of distillate was extracted. The composition of the distillate was 92% methylal and 8% methanol. 256 g of an aqueous solution containing 0.5% formaldehyde and 1.3% methanol was discharged from the bottom 4 of the tower per hour. The reaction yield based on formaldehyde was 99%.

Comparative Example 1 In Example 1, reactors B and C were removed and only reactor A was used, and the other operations were the same. 258 g of distillate per hour was obtained from the top of the column. The composition of the distillate was 92% methylal and 8% methanol. From the bottom of the tower, 283 g of an aqueous solution containing 7.2% formaldehyde and 17.6% methanol was extracted per hour. The reaction yield based on formaldehyde was 83%. The reaction yield in this example is clearly lower than in Example 1.

Example 2 In Example 1, a fourth reactor F (not shown) was further installed below reactor C, and the same operation as in Example 1 was performed. 329 g of distillate per hour was obtained from the top of the column. The composition of the distillate is 92% methylal and 8% methanol.
%Met. In addition, 0.2% formaldehyde was added from the bottom of the tower.
, 254 g of an aqueous solution containing 0.7% methanol was discharged per hour.

The reaction yield based on formaldehyde was 99.6%.

Example 3 In Example 2, a fifth reactor G (not shown) was further installed below reactor F, and the same operation as in Example 2 was performed. 330 g of distillate per hour was obtained from the top of the column. The composition of the distillate is 92% methylal and 8% methanol.
%Met. In addition, in the aqueous solution discharged from the bottom of the tower,
Formaldehyde and methanol were not detected. The reaction yield based on formaldehyde was 99.9%.

Examples 4 to 7 The same operations as in Example 1 were carried out, except that various solid acids were used instead of the macromolecular strongly acidic cation exchange resin as the solid acid catalyst. The results are summarized in Table 1.

Example 8 The same operation as in Example 3 was performed except that 600 g of a 20% formalin aqueous solution was supplied per hour instead of the 40% formalin aqueous solution. 329 g of distillate per hour was obtained from the top of the column. The composition of the distillate was 92% methylal and 8% methanol. Additionally, 554 g of an aqueous solution containing 0.1% formaldehyde and 0.3% methanol was discharged from the bottom of the tower per hour. The reaction yield based on formaldehyde was 99.6%.

Example 9 In Example 1, 140 g of ethylene glycol was supplied per hour from the feed pipe 1, and 170 g of 40% formalin per hour was supplied from the feed pipe 2. The same operation as in Example 1 was carried out, except that the reflux liquid was returned so as to maintain the temperature at the top of the column at 72°C. 1,3-dioxolane 93%, water 7% from column top 3
178g of liquid containing 100% was extracted per hour. 132 g of an aqueous solution containing 1.1% ethylene glycol and 0.5% formaldehyde was discharged from the bottom 4 of the column per hour. The reaction yield based on ethylene glycol was 99%.

Example 10 In Example 1, 115 g of t-butyl alcohol was supplied per hour from feed pipe 1, and 5 g of methanol was supplied from feed pipe 2 per hour.
0g was supplied. The same operation as in Example 1 was carried out, except that the reflux liquid was returned so as to maintain the temperature at the top of the column at 55°C. 131 g of distillate was extracted per hour from the top 3 of the column. The composition of the distillate was 97.1% L-butyl methyl ether and 2.9% methanol. 34 g of an aqueous solution containing 23.5% of mumbutyl alcohol was discharged from the bottom 4 of the column per hour.

The reaction yield was 93% based on t-butyl alcohol.

Example 11 The reactive distillation column shown in FIG. 2 was used. The number of reactors is 4
It is the basis. Reactors A, B, C, and D are each filled with 500 m (1 ml) of silica titania solid acid catalyst. 150 g of methacrylic acid is fed per hour from feed pipe 1, and reactors A, B, and B are fed from feed pipe 2. 100 g of ethanol was supplied to C and D each hour.

A packed column with a height of 2.5 m was used as the distillation column. A stage was provided in the middle of the distillation column to extract the liquid component, and the liquid component was circulated to the reactors A, B, C, and D using a pump, so as to bring about solid-liquid contact with the catalyst. Reactions IA, B, C. ．． The reaction solution containing ethyl methacrylate exiting D is returned to the distillation column, where it comes into contact with the vapor coming from the bottom of the distillation column toward the top, increasing the concentration of ethyl methacrylate.

345 g of distillate was extracted per hour from the top 3 of the column. The composition of the distillate was 89.8% ethanol and 10.2% water. 204 g of liquid was extracted from the bottom 4 of the tower per hour. The composition of the bottom liquid was 97.8% ethyl methacrylate and 2.2% methacrylic acid.

The reaction yield based on methacrylic acid was 97%.

Example 12 In Example 11, acetic acid was supplied from feed pipe 1 at 12% per hour.
0g, feed tube 2 to reactor A. ．． 110 g of methanol was supplied per hour to each of B, C, and D, and the same operation as in Example 9 was performed. 522 g of distillate per hour was obtained from the top 3 of the column.

U in distillate or methyl acetate 28%, methanol 72
%Met. Also, from the bottom 4 of the tower, 6.4% acetic acid and 93% water were added.
38 g of an aqueous solution containing 6% was extracted per hour. The reaction yield based on acetic acid was 98%.

Example 13 In Example I, 130 g of dioxymethylene dimethyl ether was supplied per hour from feed pipe 1, and 150 g of water was supplied per hour from feed pipe 2, and the same operation as in Example 1 was performed, with the reflux ratio being 1. 241 g of distillate was extracted per hour from the top 3 of the column. Methanol in the distillate 32.4%,
It was an aqueous solution containing 30.3% formaldehyde. Dioxymethylene dimethyl ether 1.7% from column bottom 4
39g of an aqueous solution containing was discharged per hour. The hydrolysis rate based on dioxymethylene dimethyl ether was 99.5%.

(Effects of the Invention) (1) Since a solid catalyst is used, it is easy to separate the catalyst from liquids such as unreacted reactive substances and by-products.

Homogeneous catalysts such as sulfuric acid require operations such as distillation and neutralization to separate the catalyst from the reaction liquid, but this is not particularly necessary in the present invention.

(2) Continuous operation for long periods of time is possible. Since the reactor is forced circulation from the outside, if a spare reactor is installed, catalyst regeneration, replacement, and removal can be performed through the spare reactor, so there is no need to stop production.

(3) High reaction yield. In particular, in the methylal production reaction, the reaction yield is 98% or more based on formaldehyde. can be easily achieved.

(4) An aqueous formalin solution can be used as a raw material in the methylal production reaction.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the apparatus of the present invention used in Example 1, and FIG. 2 is an explanatory diagram of the apparatus of the present invention used in Example 11. 1.2...Feed pipe 3...Tower top 4...Tower bottom A, B, C, D...Reactor E ・Distillation column (and 1 other name)

Claims (2)

[Claims] (1) A liquid containing a reactive substance with reaction equilibrium of two or more components is brought into solid-liquid contact with a solid acid or solid base catalyst to obtain a component enriched in one component of the reaction product with reaction equilibrium as a distillate component. An apparatus comprising at least two or more reactors filled with a solid acid or solid base catalyst, at least one of which reacts with a reaction product of two or more reactive substances and two or more components. The vapor of the reaction liquid that has come into solid-liquid contact in at least one reactor is forcibly circulated in another reactor and is in contact with the reactive substance that has come into solid-liquid contact. A reactive distillation apparatus characterized in that the concentration of one component of the reaction product in the vapor phase is increased by bringing the liquid containing the reaction product into gas-liquid contact. (2) The reactive distillation apparatus according to claim 1, wherein the reactor filled with a solid acid or solid base catalyst is connected to a distillation column.