JPH10113564A - Heteropolyacid containing catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a catalyst which generates no elusion of a heteropolyacid into a reaction liquid when being used as a catalyst for various kinds of liquid phase reaction and can be recovered easily from the reaction liquid. SOLUTION: A heteropolyacid containing catalyst is composed of a mixture of a heteropolyacid, for example, 12-molybdophosphoric acid and a porous material, for example, Y type zeolite, and the heteropolyacid is contained in the molecular shape in pares of the porous material, and the amount of heteropolyacid is 1% or less of the containing amount when the catalyst is imamersed in the normal temperature water and hot water. The catalyst is manufactured by synthesizing the heteropolyacid in the pores of the porous material. As the heteropolyacid is of the molecular shape and dispersion fixed, the catalyst is provided with the high efficiency as a liquid phase reaction catalyst. The heteropolyaicd containing catalyst can be synthesized by an extremely simple process in which the conventional synthesis of a heteropolyacid is carried out in the liquid containing the porous material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an immobilized catalyst containing a heteropolyacid and a method for producing the same.

[0002]

2. Description of the Related Art Heteropolyacids generally have a large molecular diameter of about 1 nm. Due to their electronic and steric molecular characteristics, they are used in alcohol dehydration reactions, tetrahydrofuran ring-opening polymerization reactions, olefin hydration reactions, and the like. It exhibits higher acid catalytic activity than ordinary mineral acids and Lewis acids, and also has redox activity. As described above, heteropolyacids have excellent performance, and thus have attracted attention as important substances in recent years.

However, since heteropoly acids are very soluble in water and other oxygen-containing solvents (eg, alcohols), it is very difficult to separate and recover the reacted heteropoly acids from the reaction mixture when used as a catalyst. is there. For this reason, various heteropolyacids insolubilized in oxygen-containing solvents have been proposed, but these are not sufficiently satisfactory industrially. At present, the heteropolyacid is only partially used industrially as a liquid layer homogeneous catalyst in the dehydration reaction of alcohol, the ring-opening polymerization reaction of tetrahydrofuran, and the like.

[0004] The above-mentioned proposed insolubilized heteropolyacids include heteropolyacid salts obtained by exchanging hydrogen of heteropolyacid with a cation having a relatively large ionic radius, for example, cesium ion, rubidium ion and potassium ion, or heteropolyacid and metal oxide. In some cases, a heteropolyacid crystal is contained and fixed in a metal oxide by baking a mixture with the sol. However, when a heteropolyacid salt is also applied to a reaction using a large amount of an oxygen-containing solvent, particles of the heteropolyacid salt are finely dispersed and dispersed in a colloidal form, so that the heteropolyacid salt is difficult to separate from the reaction solution after the reaction. On the other hand, the included crystalline heteropolyacid gradually decomposes the calcined product of the metal oxide sol in a large amount of the oxygen-containing solvent, and accordingly desorbs into the oxygen-containing solvent.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made even when used in a reaction under a liquid phase in which a large amount of an oxygen-containing solvent is present.
An object of the present invention is to provide a heteropolyacid-containing catalyst which can be easily separated and recovered from a reaction solution after the reaction, and a method for producing the same.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies on a method for preparing a heteropoly acid, and as a result, have noticed that the molecular size of a heteropoly acid is relatively large, generally about 1 nm. When a molecular heteropolyacid is synthesized in the pores of a porous material having pores, the synthesized heteropolyacid is contained and immobilized in the pores, and the heteropolyacid is substantially removed from the oxygen-containing solvent. It was possible to obtain a catalyst which was not released, and completed the present invention.

That is, the present invention provides a heteropolyacid-containing catalyst comprising a mixture of a heteropolyacid and a porous material, wherein the heteropolyacid is molecularly contained in pores of the porous material. An object of the present invention is to provide a method for producing the heteropolyacid-containing catalyst, wherein the acid is synthesized in pores of a porous material.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The heteropolyacid in the present invention is
Among polyacids formed by condensation of inorganic acids, those composed of two or more metals, polyacid atoms and heteroatoms. The heteropolyacid in the present invention includes not only a free acid but also a salt thereof. Examples of the polyacid atoms constituting the heteropolyacid include chromium, vanadium, molybdenum, tungsten, manganese and the like. Preferred polyacid atoms are molybdenum and tungsten. Examples of heteroatoms include phosphorus, arsenic, silicon, germanium, titanium, zirconium, and the like. The preferred heteroatom is phosphorus. Representative heteropolyacids that can be suitably used in the present invention are, for example, 12-tungstophosphoric acid, 12-molybdophosphoric acid, 12-tungstosilicic acid, 12-molybdosilicic acid, and 11-molybdo-1.
-A Keggin-type heteropolyacid such as vanatophosphoric acid,
Dawson-type heteropolyacids such as 18-tungstodiphosphate and 18-molybdophosphoric acid, defective Keggin-type heteropolyacids such as 11-molybdophosphate, and the like, and partially neutralized salts thereof with alkali metal ions or ammonium ions are given. be able to.

On the other hand, as the porous material in the present invention, known compounds can be employed without any limitation.
Specifically, zeolites such as Y-type, ALPO, SAPO,
Activated carbon etc. are mentioned. Particularly preferred porous materials are those having pores that are sized for the heteropolyacid to be included. For example, for 12-molybdophosphoric acid, Y
Examples include porous materials such as molds, zeolites such as SAPO, and activated carbon.

The heteropolyacid-containing catalyst of the present invention is a mixture of a heteropolyacid and a porous material, wherein the heteropolyacid molecules are contained within pores of the porous material (ie, so as to be surrounded by the material). To) is fixed. The content of the heteropolyacid is not particularly limited, and may be any amount that does not impair the original catalytic ability of the heteropolyacid.

The heteropolyacid-containing catalyst of the present invention has very little elimination of heteropolyacid even when immersed in an oxygen-containing solvent. That is, 1.0 g of the heteropolyacid-containing catalyst of the present invention was added to 8
When immersed in 500 g of hot water at 0 ° C for 3 hours and at 20 ° C
Of the heteropolyacid when immersed in 500 g of room temperature water for 3 hours is 1% or less of the included heteropolyacid. When the amount of heteropoly desorbed exceeds 1%, when the heteropolyacid-containing catalyst of the present invention is used in a reaction in a large amount of an oxygen-containing solvent, the heteropolyacid is desorbed from the catalyst, and the recovery rate is reduced. It is not preferable because it decreases. If the heteropoly acid is simply supported on the porous material, almost all of the heteropoly acid is eliminated by immersion in water, as is apparent from the comparative examples described later. Small amounts of catalyst cannot be obtained.

The particle diameter of the heteropolyacid-containing catalyst of the present invention is not particularly limited, but is usually in the range of 0.1 to 1000 μm.

Although the heteropolyacid-containing catalyst of the present invention may be produced by any method, it can be suitably produced by the following method. That is, this is a method of synthesizing a heteropoly acid in the pores of the porous material by synthesizing the heteropoly acid in the presence of the porous material.

The heteropoly acid can be produced by a known method. For example, it can be obtained by heating an acidic aqueous solution containing a salt serving as a source of a polyacid atom and a simple oxygen acid of a hetero atom or a salt thereof.

Next, an embodiment of a method for synthesizing a heteropolyacid in the pores of the porous material by synthesizing the heteropolyacid in the presence of the porous material will be described. 100 parts by weight of porous material and 3000 to 400 water
A source of polyacid atoms 30 in a suspension consisting of 0 parts by weight.
0 to 450 parts by weight and 20 to 30 parts by weight of a heteroatom source are added. Preferably, either one of a polyacid atom source and a heteroatom source is added to the suspension, and then left to stand. After that, the raw material is sufficiently penetrated into the pores of the porous material, and then the other raw material is added.
By stirring at 0 ° C. for 2 to 5 hours, a heteropolyacid is synthesized in the pores of the porous material, and the heteropolyacid-containing catalyst of the present invention can be obtained.

When the porous material contains a component that decomposes the heteropolyacid, a pretreatment for removing the decomposed component is performed on the porous material when the heteropolyacid is synthesized in the pores of the porous material. It is preferred to apply. Examples of the pretreatment when the component that decomposes the heteropolyacid is aluminum include a steam treatment and an acid treatment.

In order to allow the source of polyacid atoms and the source of heteroatoms to easily enter the pores of the porous material, air bubbles in the pores are discharged in advance, and then water is introduced into the pores. Is preferred. It is more preferable that the heteropolyacid is synthesized in the pores of the porous material after the bubble discharge / water introduction operation and the pretreatment described above are used in combination.

Suitable sources of polyacid atoms that can be used in the synthesis of heteropolyacid in the present invention include molybdenum oxide, sodium molybdate, tungsten oxide, sodium tungstate and the like. Suitable sources of heteroatoms include phosphoric acid, water glass, sodium silicate, and the like. The order of adding the source of the polyacid atom and the source of the heteroatom is not particularly limited.

The mixed solution thus obtained contains, besides water and a catalyst containing heteropolyacid, a heteropolyacid synthesized outside the pores and an unreacted raw material. Thus, the heteropolyacid-containing catalyst is separated by a known method such as filtration or centrifugation, washed with warm water, and dried to obtain the heteropolyacid-containing catalyst of the present invention.

[0020]

According to the heteropolyacid-containing catalyst of the present invention, since the heteropolyacid molecule is fixed so as to be surrounded by the porous material, the amount of the released heteropolyacid in the oxygen-containing solvent is extremely small. Few. Therefore, when used for various liquid phase reactions, the heteropolyacid is rarely eliminated from the reaction solution during the reaction, and it is very easy to recover the catalyst from the reaction solution after the reaction. In addition, the heteropolyacid-containing catalyst of the present invention has a high efficiency as a liquid phase reaction catalyst because the heteropolyacid is dispersed and fixed in a molecular form.
Further, the heteropolyacid-containing catalyst of the present invention can be synthesized by a very simple method such as synthesis of a conventional heteropolyacid in a liquid containing a porous material.

Therefore, the heteropolyacid-containing catalyst of the present invention can be used like a conventional free heteropolyacid in a wide variety of heteropolyacid-specific acid-catalyzed reactions and oxidation-reduction reactions, and the recovery after the reaction is extremely simple. It is a very excellent catalyst that can be used repeatedly.

[0022]

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

Example 1 In 70 g of deionized water, 2.0 g of Y-type zeolite was added, 7.2 g of molybdenum oxide was added, and the mixture was stirred for 24 hours. The raw material was sufficiently penetrated into the pores of zeolite. Then 85
0.48 g of a phosphoric acid aqueous solution (0.48 g) is added, and the mixture is stirred at about 95 ° C. for 3 hours. The yellow suspension obtained is filtered and the solid obtained is washed with 500 g of deionized water or 500 g of warm water. The washed solid is dried to obtain a Y-type zeolite catalyst containing 12-molybdophosphoric acid. The content of 12-molybdophosphoric acid in this catalyst was 6% by weight.

Even if the catalyst thus obtained is immersed again in warm water and stirred for 3 hours, the amount of 12-molybdophosphoric acid to be eliminated is 1% or less of the included amount. In addition, the catalyst can be easily separated from warm water by using filter paper.

FIG. 1 shows a Fourier transform infrared spectrophotometer spectrum of the Y-type zeolite catalyst containing 12-molybdophosphoric acid. Of the four peaks specific to 12-molybdophosphate, one cannot be identified because it overlaps with the peak of the Y-type zeolite as a carrier, but the remaining three peaks can be confirmed,
2 shows the presence of 12-molybdophosphoric acid in the catalyst.

Comparative Example 12 10 g of 12-molybdophosphoric acid and 2.0 g of Y-type zeolite
Is placed in 70 g of deionized water, stirred overnight and the resulting yellow solid is filtered off. When this solid is washed with 500 g of warm water, almost all of 12-molybdophosphoric acid is eliminated.

As is clear from the above description, the present invention also provides the following inventions. A method for immobilizing a heteropoly acid, comprising synthesizing a heteropoly acid in pores of a porous material and immobilizing the heteropoly acid in the pores. A method for immobilizing a heteropoly acid, comprising synthesizing a heteropoly acid in the pores of the porous material and synthesizing the heteropoly acid in the pores by synthesizing the heteropoly acid in the presence of the porous material. The immobilization method according to claim 1, wherein a pretreatment for removing a decomposition component of the heteropolyacid contained in the porous material is performed on the porous material, and then the heteropolyacid is synthesized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a Fourier transform infrared spectrophotometer spectrum of the catalyst, 12-molybdophosphoric acid and Y-type zeolite obtained in Example 1 of the present invention.

Continued on the front page (72) Inventor Minoru Mukai 151-2-1 Idemagawa-dori Sengen-Higashi-funain-maecho, Kamigyo-ku, Kyoto No. 2 1001 De Reed Imadegawa-dori

Claims (6)

[Claims] 1. A heteropolyacid-containing catalyst comprising a mixture of a heteropolyacid and a porous material, wherein the heteropolyacid is molecularly contained in pores of the porous material. 2. The heteropolyacid-containing catalyst according to claim 1, wherein the heteropolyacid is synthesized in pores of the porous material. 3. The heteropolyacid-containing catalyst according to claim 1, wherein the amount of the desorbed heteropolyacid when immersed in room temperature water or hot water is 1% or less of the included amount. 4. The method for producing a heteropolyacid-containing catalyst according to claim 1, wherein the heteropolyacid is synthesized in the pores of the porous material. 5. The process for producing a heteropolyacid-containing catalyst according to claim 1, wherein the heteropolyacid is synthesized in the pores of the porous material by synthesizing the heteropolyacid in the presence of the porous material. Method. 6. The synthesis of a heteropoly acid according to claim 4 or 5, wherein a pretreatment for removing a decomposition component of the heteropoly acid contained in the porous material is performed on the porous material, and then the synthesis of the heteropoly acid is performed. Production method.