JPH0691171A - Catalyst carrying salt of heteropolyacid - Google Patents

Abstract

PURPOSE:To provide a catalyst preventing the release of an insoluble salt of a heteropolyacid into a reactive soln. when used as a catalyst for a liq. phase reaction, capable of easily recovering from the reactive soln. after the reaction and maintaining catalytic function peculiar to the insoluble salt. CONSTITUTION:A mixture of an insoluble salt of a heteropolyacid such as cesium 1,2-tungstophosphate with a sol of a metal oxide such as silica is fired, e.g. at 100-600 deg.C to produce the objective catalyst made of a mixture of the insoluble salt with the metal oxide. When this catalyst is immersed in water, the insoluble salt is released by <=5wt.%.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a catalyst in which an insoluble heteropolyacid salt is immobilized and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Heteropoly acids and their salts are important substances which are widely used industrially as effective catalysts for reactions such as hydration of olefins, polymerization of tetrahydrofuran and oxidation of methacrolein. However, since the heteropolyacid and its salt are soluble in polar solvents such as water and alcohol, there is a problem that it is difficult to recover the heteropolyacid from the reaction solution after using it as a catalyst. Therefore, in order to make it insoluble in a polar solvent, conversion to a salt having a cation with a relatively large ionic radius, for example, a cesium salt, a rubidium salt, a potassium salt, an ammonium salt, a barium salt, or an acid salt thereof is performed. ing.

However, when this insoluble heteropolyacid salt is also used as a catalyst for a hydrolysis reaction or a hydration reaction using a large amount of polar solvent, the particles of the insoluble heteropolyacid salt become fine crystals and are dispersed in a colloidal form. There was also a problem that the catalyst could not be separated from the reaction solution after the reaction.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is possible to perform hydrolysis reaction, hydration reaction, etc. without impairing the excellent catalytic function of the heteropolyacid salt. An object of the present invention is to provide a solid catalyst which can be easily separated and recovered from the reaction solution after the reaction even when used in the reaction in a liquid phase in which a large amount of polar solvent is present.

[0005]

Means for Solving the Problems The present inventor has conducted extensive research on a method for preparing a heteropolyacid salt while advancing the development of acid-base and acid reduction catalysts for heteropolyacid derivatives.
As a result, if the insoluble heteropolyacid salt and the silica gel carrier are simply mixed, the insoluble heteropolyacid salt will be desorbed from the carrier in the polar solvent. Alternatively, by producing a sol of a metal compound in the presence of an insoluble heteropolyacid salt to obtain a mixture thereof, the insoluble heteropolyacid salt is eliminated even in a polar solvent without lowering the catalytic activity of the insoluble heteropolyacid salt. It was possible to obtain a catalyst that does not exist, which led to the present invention.

That is, the present invention is composed of a mixture of an insoluble heteropolyacid salt and a metal oxide, and the amount of the insoluble heteropolyacid salt released when immersed in water is 5% by weight or less. It is a heteropolyacid salt-supported catalyst.

The insoluble heteropolyacid salt used in the present invention is not particularly limited, and known compounds can be used. Typical heteropolyacids that can be preferably used in the present invention are 12-molybdophosphoric acid,
12-molybdosilicic acid, 12-tungstophosphoric acid, 12
Examples thereof include Keggin-type heteropolyacids such as tungstosilicic acid; mixed coordination heteropolyacids; Dawson-type molybdophosphoric acid; 11-molybdophosphoric acid and other defective Kegginn-type heteropolyacids. Examples of salts of these heteropolyacids include cesium salts, rubidium salts, potassium salts, ammonium salts, barium salts, organic ammonium salts, and acidic salts thereof.

On the other hand, as the metal oxide in the present invention, known compounds can be adopted without any limitation,
In particular, a metal oxide used as a catalyst carrier is suitable. Specific examples of such metal oxides include silica, alumina, titania, zirconia, or composite oxides such as silica-alumina, silica-titania, and silica-zirconia.

The insoluble heteropolyacid salt-supported catalyst of the present invention is a mixture of the above-mentioned insoluble heteropolyacid salt and a metal oxide. The mixing ratio of the insoluble heteropolyacid salt and the metal oxide is not particularly limited, but in order to reduce the elimination of the insoluble heteropolyacid salt without impairing the original catalytic function of the insoluble heteropolyacid salt, the insoluble heteropolyacid salt is insoluble by weight. Heteropolyacid salt: Metal oxide = 1: 0.05 to 5.0
It is preferable that the range is 1: 0.1 to 2.
It is preferably in the range of 0.

The insoluble heteropolyacid salt-supported catalyst of the present invention has very little elimination of the insoluble heteropolyacid salt even when immersed in a polar solvent. That is, the amount of the insoluble heteropolyacid salt desorbed when the insoluble heteropolyacid salt-supported catalyst of the present invention was immersed in warm water at 60 ° C. for 1 hour was 5% by weight in the proportion of the supported insoluble heteropolyacid salt. Is
Further, it may be 2% by weight or less. When the amount of the insoluble heteropolyacid salt desorbed exceeds 5% by weight, when the insoluble heteropolyacid salt-supported catalyst of the present invention is used for the reaction in a large amount of polar solvent, the insoluble heteropolyacid salt is eliminated from the catalyst. It is not preferable because the recovery rate is lowered. By simply mixing the insoluble heteropolyacid salt and the metal oxide, as is clear from the comparative example described later, almost all of the insoluble heteropolyacid salt is desorbed by immersion in water, and thus, as in the present invention. It is not possible to obtain a catalyst with a small amount of insoluble heteropolyacid salt eliminated.

The insoluble heteropolyacid salt-supported catalyst of the present invention is usually 50 to 2000 m ² / g, preferably 100.
It has a specific surface area of ˜1000 m ² / g. The particle size is not particularly limited, but is usually 0.1 to 1000 μm.
The range is m.

The heteropolyacid salt-supported catalyst of the present invention may be produced by any method, but can be suitably produced by the following method. That is, it is a method of firing a mixture of an insoluble heteropolyacid salt and a sol of a metal oxide.

The metal oxide sol can be produced by a known method. For example, it can be produced by hydrolyzing a hydrolyzable organometallic compound in the presence of water, or by acidolyzing a silicate. Here, as the hydrolyzable organometallic compound, tetraethoxysilane, tetraisopropoxysilane, triethoxyaluminum, tetraisopropoxytitanium, an organosilicon compound having an alkoxy group such as tetraisopropoxyzirconium, an organoaluminum compound, an organic compound. Examples thereof include titanium compounds and organic zirconium compounds, and examples of acid-decomposable silicates include sodium silicate.

To hydrolyze the organometallic compound, the above-mentioned raw materials are dissolved in alcohol such as methanol and ethanol, and then 1 to 10 moles of water is added to the alkoxy group of the hydrolyzable organometallic compound. A known method of hydrolysis can be adopted. For the acid decomposition of the silicate, a known method of adding sulfuric acid or an aqueous solution of sulfate to an aqueous solution of silicate can be adopted.

The method for mixing the metal oxide sol and the insoluble heteropolyacid salt is not particularly limited, and the above-mentioned hydrolyzable organometallic compound or acid-decomposable silicate which is a raw material of the metal oxide sol may be used. A method of adding an insoluble heteropolyacid salt after hydrolysis or acid decomposition, a method of hydrolyzing a hydrolyzable organometallic compound in the presence of the insoluble heteropolyacid salt, and the like can be adopted.

The metal oxide-insoluble heteropolyacid salt and the sol of the metal oxide may be mixed in the above-mentioned weight ratio.

The mixture of the insoluble heteropolyacid salt and the sol of the metal oxide is separated from the reaction solution in the reaction for producing the sol of the metal oxide by a known method such as evaporation to dryness, filtration and centrifugation. Then, if necessary, it is dried and then fired. The calcination temperature is not particularly limited, but in order to reduce the amount of desorption without impairing the catalytic function of the insoluble heteropolyacid salt, 100 to 600 ° C, preferably 150 to 5
It is preferable to select from the range of 00 ° C. Further, the firing time is generally preferably selected from the range of 1 to 5 hours.

[0018]

INDUSTRIAL APPLICABILITY The insoluble heteropolyacid salt-supported catalyst of the present invention has an extremely small amount of desorbed insoluble heteropolyacid salt in a polar solvent, and therefore is insoluble in the reaction solution even when used in various reactions. The elimination of the heteropolyacid salt can be prevented, and it can be easily recovered from the reaction solution after the reaction. Moreover, the insoluble heteropolyacid salt-supported catalyst of the present invention has fine crystals of the insoluble heteropolyacid salt uniformly dispersed and immobilized in the metal oxide matrix, and has high efficiency as a liquid-phase reaction catalyst and is insoluble. The catalytic function originally possessed by the heteropolyacid salt is hardly impaired.

Therefore, the insoluble heteropolyacid salt-supported catalyst of the present invention can be applied to a wide range of heteropolyacid salt-specific acid-catalyzed reactions or redox reactions such as olefin hydration, ester hydrolysis, and nitrile hydrolysis. It effectively functions as a catalyst in, and can be suitably used for a liquid phase reaction using a solvent or a reaction substrate having a particularly high polarity.

[0020]

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 2 g of cesium 12-tungstophosphoric acid having a composition of H _0.5 Cs _2.5 PW ₁₂ O ₄₀ was dispersed in 15 ml of ethanol and 4
The mixture was stirred at 0 ° C for 1 hour. Then, a predetermined amount of tetraethoxysilane was added dropwise, and the mixture was stirred at 40 ° C. for 1 hour, and then water was added in an amount 5 times the molar amount of tetraethoxysilane.
The mixture was stirred at ° C for 24 hours. The reaction liquid containing the generated sol and solid was evaporated to dryness under reduced pressure, the collected solid was added to water at 80 ° C., the mixture was stirred for 15 hours, and then filtered using a filter paper,
After washing with water, drying, and calcination at 300 ° C., insoluble cesium tungstophosphoric acid immobilized with silica was obtained. In addition, silica-immobilized insoluble cesium tungstophosphoric acid salts having different silica contents were prepared in the same manner as above.

0.5 mmol of these insoluble cesium salts of insoluble tungstophosphoric acid immobilized on silica were added to 100 m of warm water at 60 ° C.
The amount of insoluble cesium tungstophosphate desorbed in warm water after immersing in 1 l for 1 hour was quantified, and the results are shown in Table 1. Further, the reaction rates in the hydrolysis of ethyl acetate carried out to evaluate the composition ratio, the specific surface area and the catalytic function are summarized in Table 1. For the hydrolysis reaction of ethyl acetate, 9.5 g of water, 0.5 g of ethyl acetate and 0.5 mmol of insoluble cesium salt of insoluble tungstophosphoric acid immobilized on silica were used.
The reaction temperature was 60 ° C.

After the hydrolysis reaction, any silica-immobilized insoluble cesium tungstophosphoric acid salt could be easily separated from the liquid phase by using a filter paper.

[0024]

[Table 1]

Example 2 H _0.5 Cs _2.5 PW ₁₂ O was prepared in the same manner as in Example 1 except for the firing temperature.
Table 2 shows the results when the silica-immobilized insoluble cesium tungstophosphoric acid salt having a weight ratio of silica to ₄₀ of 1.2 was prepared and the firing temperature was changed.

[0026]

[Table 2]

Example 3 H ₂ CsPW ₁₂ O ₄₀ and HCs ₂ PW instead of H _0.5 Cs _2.5 PW ₁₂ O ₄₀
Same as Example 1 except that ₁₂ O ₄₀ was used, the amount of tetraethoxysilane was regulated so that the weight ratio of silica to insoluble cesium tungstophosphoric acid salt was 1.2, and the firing temperature was 150 ° C. , Silica-immobilized insoluble cesium salt of tungstophosphoric acid was prepared. The results are shown in Table 3.

[0028]

[Table 3]

Comparative Example 2 _0.5 g of cesium 12-tungstophosphoric acid having a composition of H _0.5 Cs _2.5 PW ₁₂ O ₄₀ was dispersed in 15 ml of water, and the mixture was stirred at 40 ° C. for 1 hour.
Stir for hours. Then silica gel (specific surface area 585 cm
2.4 g of ( ² / g) was added, and the mixture was stirred at 40 ° C. for 1 hour. Thereafter, in the same manner as in Example 1, a mixture of insoluble cesium tungstophosphoric acid salt and silica having a weight ratio of silica to insoluble cesium tungstophosphoric acid of 1.2 was prepared. This mixture was evaluated in the same manner as in Example 1. As a result, the reaction rate in the hydrolysis of ethyl acetate was 2.04 × 10 ⁻³ min ⁻¹ g ⁻¹ , but most of the insoluble cesium tungstophosphoric acid salt was desorbed in warm water.

[Procedure amendment]

[Submission date] May 10, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

To hydrolyze the organometallic compound, the above-mentioned raw materials are dissolved in alcohol such as methanol and ethanol, and then 0.1 to 10 times mol of water is added to the alkoxy group of the hydrolyzable organometallic compound. In addition, known methods of hydrolysis can be adopted. For the acid decomposition of the silicate, a known method of adding sulfuric acid or an aqueous solution of sulfate to an aqueous solution of silicate can be adopted.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

0.5 mmol of these insoluble cesium salts of insoluble tungstophosphoric acid immobilized on silica were added to 100 m of warm water at 60 ° C.
The amount of insoluble cesium tungstophosphate desorbed in warm water after immersing in 1 l for 1 hour was quantified, and the results are shown in Table 1. In addition, the specific surface area is measured separately, and the catalyst
Hydrolysis of ethyl acetate was performed to evaluate its performance.
The reaction rates are summarized in Table 1. The hydrolysis reaction of ethyl acetate was performed at a reaction temperature of 60 ° C. using 9.5 g of water, 0.5 g of ethyl acetate, and 0.5 mmol of insoluble cesium salt of insoluble tungstophosphoric acid immobilized on silica.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

Example 3 Instead of H _0.5 Cs _2.5 PW ₁₂ O ₄₀ , the heteropolyacids shown in Table 3
The weight ratio of silica to heteropolyacid salt is
Adjust the amount of tetraethoxysilane to 1.2
However, the same as Example 1 except that the firing temperature was 150 ° C.
Then, a silica-immobilized insoluble heteropolyacid salt was prepared.
The results are shown in Table 3.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

[0028]

[Table 3]

Claims (2)

[Claims] 1. An insoluble heteropolyacid salt carrier comprising a mixture of an insoluble heteropolyacid salt and a metal oxide, wherein the amount of the insoluble heteropolyacid salt desorbed when immersed in water is 5% by weight or less. catalyst. 2. The method for producing an insoluble heteropolyacid salt-supported catalyst according to claim 1, wherein a mixture of an insoluble heteropolyacid salt and a sol of a metal oxide is calcined.