JPH09267042A - Acid catalyst consisting of acid salt of heteropoly-acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an acid catalyst hardly causing a deterioration of activity and having a long service life by using an acid salt of a heteropoly-acid having specified values of specific surface area, fine pore volume and pore diameter, respectively and exhibiting a specified acid content value. SOLUTION: In the acid catalyst consisting of the acid salt of the heteropoly- acid having mesopores useful for various kinds of org. reactions, the acid salt of the heteropoly-acid having >=10m<2> /g specific surface area, >=0.01cc/g fine pore volume, in which >=30% of total fine pores have >=40Å pore size and having an acid content having <=3.3 H0 is 0.1-3.0mmol/g is used. At this time, phosphotungstic acid, silicotungstic acid, phosphomolybdic acid, etc., are used as the heteropoly-acid, and the acid salt of the heteropoly-acid is treated at >=120 deg.C with a gaseous polar solvent after previously drying at >=160 deg.C. In this case, an org. carboxylic acid or an org. carboxylate are used as the polar solvent.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an acid catalyst comprising an acid salt of a heteropolyacid having a mesopore useful for various organic reactions.

[0002]

2. Description of the Related Art Heteropolyacids can be used as acid catalysts or oxidation catalysts, in solution systems or solids, because they can control acid and oxidative power, and have a pseudo liquid phase behavior and a unique coordination power. Widely used in catalyst systems. Among them, cesium salts and potassium salts of heteropolyacids are solid acids and retain strong acids, so that they are being developed as promising catalysts with high activity. For example, there is a method for producing a lower fatty acid ester (JP-A-4-139149).

The pore size of the heteropolyacid salt depends on various conditions, but in particular, it varies depending on the ratio of the heteropolyacid and the cation source added to form the heteropolyacid salt. For example, phosphotungstic acid (H ₃ PW ₁₂
The pore size of the cesium salt of O ₄₀ ) is Cs _2.1 H _0.9 PW ₁₂
When it is O ₄₀ , it is 5.85Å or less, and Cs _2.5 H _0.5 PW
₁₂ O ₄₀ is at least 8.5 Å (Toshio Okuhara Catalyst vol.
37 No. 8 1995), and the pore size increases as the amount of cesium increases. However, as the amount of cesium increases, the acidity decreases, so the performance as an acid catalyst decreases. The pores of the heteropolyacid salt while maintaining the required acidity are microporous (8-20
Heteropolyacid salt catalysts having a size of Å) and having a mesoporous property (20 to 500Å) suitable for a reaction involving a bulky molecule have not been found so far.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an acid catalyst composed of an acid salt of a heteropoly acid having pores with a large pore size.

[0005]

The inventors of the present invention have found that pores having a specific surface area of 10 m ² / g or more, a pore volume of 0.01 cc / g or more, and a pore diameter of 40 Å or more are 30% or more of all pores and H _0. Heteropolyacid salt-based catalysts having an acid amount of 3.3 or less of 0.1 to 3.0 mmol / g show less activity reduction and a longer catalyst life in various organic reactions, particularly reactions involving bulky molecules. They have found that they are effective as catalysts, and have completed the present invention.

The heteropolyacid in the present invention is a condensed oxyacid of a coordination atom forming a basic skeleton and an oxo acid of a heteroatom. Heteropolyacids consist of hydrogen, heteroatoms, polyatoms, and oxygen. Specific examples of the hetero atom include phosphorus, germanium, boron or silicon. As a poly atom, the periodic table (according to the International Union of Pure and Applied Chemistry, Inorganic Chemistry Nomenclature Revised Edition (1989)) 4A
~ 7A group elements, specifically tungsten, molybdenum,
Examples include niobium, tantalum and vanadium. Specific compounds include phosphotungstic acid, phosphomolybdic acid,
Examples thereof include silicotungstic acid, silicomolybdic acid and phosphovanadomolybdic acid.

In the catalyst of the present invention, the acid salt of the above heteropoly acid is used. This acidic salt is obtained by substituting a part of hydrogen of the above heteropolyacid with a cation having a ionic radius of 1.1 Å or more and a monovalent valence. Examples of the atom or group of atoms having a ionic radius of 1.1 Å or more and forming a cation having a valence of 1 to 3,
Specific examples include cesium, rubidium, thallium, potassium, sodium, strontium, aluminum, gallium, alkylammonium groups, barium, gold, lithium, copper, magnesium and alkylamino groups. Cesium is preferred.

The ionic radius is Shannon and Perw.
Itt was obtained by Shannon's improvement of the value arranged based on the actual measurement, and the value is a hexacoordinate value assuming that the radii of hexacoordination O ²⁻ and F ⁻ are 1.26Å. For example, Ba ²⁺ (1.19Å), Au ⁺ (1.51Å), Na ⁺
(1.16Å), Ag ⁺ (1.29Å), Sr ²⁺ (1.
32Å). The acidic salt of these heteropolyacids may contain water of crystallization.

Specific examples of the acid salt of the heteropolyacid salt include cesium phosphotungstic acid salt, potassium phosphotungstic acid salt, sodium phosphotungstic acid salt, strontium phosphotungstic acid salt, and cesium silicotungstic acid salt. Salt, potassium tungstic acid, sodium tungstic acid, strontium tungstic acid, cesium phosphomolybdic acid, potassium phosphomolybdic acid, sodium phosphomolybdic acid, strontium phosphomolybdic acid Examples thereof include a cesium salt of silicomolybdic acid, a potassium salt of silicomolybdic acid, a sodium salt of silicomolybdic acid, and a strontium salt of silicomolybdic acid.

The ratio of the heteropolyacid and the cation can be selected according to the purpose. Preferably heteropolyacid 1
It is formulated so that 0.05 to 2.9 grams of hydrogen atoms are replaced per mole. Further, two or more kinds of cations may be used at the same time. The specific surface area in the present invention is determined by measuring the nitrogen gas adsorption amount at −196 ° C. by the adsorption method,
It was calculated from the formula of T. The specific surface area of the catalyst of the present invention is 10 m ²
/ G or more, preferably 40 m ² / g or more.
When the specific surface area is 10 m ² / g or less, the catalytic activity is lowered.

The pore volume in the present invention was calculated from the difference between the volume of the container in which the sample was placed, the volume of the volume filled with nitrogen when the catalyst was placed and when the volume was empty, and measurement under constant pressure (760 mmHg). The sample catalyst used was one heated in vacuum at 105 ° C. The pore volume of the catalyst of the present invention is 0.01 cc / g or more, preferably 0.05 cc / g or more. When the pore volume is less than 0.01 cc / g, the catalyst life is short and bulky molecules cannot be reacted.

The value of the pore distribution of the present invention refers to a value calculated by measuring the gas adsorption amount by the gas adsorption method and using the Kelvin equation. In the pore distribution of the catalyst of the present invention, the proportion of pores having a volume of 40 liters or more is 30% or more, preferably 35 to 98%, and particularly preferably 40 to 80%. If the ratio of pores of 40 Å or more is less than 30%, it is not suitable for reaction of bulky molecules. The acid amount of the present invention was determined by the indicator method. The indicator method is a non-polar solvent in the presence of various indicators having different pKa,
This is a method of obtaining an acid strength distribution by performing titration with a basic reagent. What is called a Hammett indicator is used as the basic reagent.

The acid amount of the catalyst of the present invention is 0.1 to 3 when the Hammett acidity function H ₀ showing the acid strength is 3.3 or less.
It is 0 mmol / g. The amount of acid with H 2 _O of 3.3 or less is 0.
If it is less than 1 mmol / g, the catalytic activity is lowered. 3.
When it exceeds 0 mmol / g, the proportion of mesoporous size pores decreases.

The method for preparing the acid catalyst of the present invention includes:
First, an acid salt of heteropolyacid is obtained by a usual method. That is, the cation source is dissolved in a suitable solvent and the heteropolyacid solution (eg, aqueous solution) is stirred at room temperature.
The heteropolyacid salt is precipitated when the solution is dripped into. Examples of the cation source include cesium nitrate, potassium nitrate, alkylammonium and the like. The solution containing the precipitated heteropolyacid salt is immersed in a water bath at 90 ° C. and aged for 1 hour. Further, it was dissolved in water in an amount equal to that of the obtained heteropolyacid salt,
Dry at 5 ° C for 5 hours. The drying means, temperature, and time depend on the type of heteropolyacid and the amount of cations.

The thus obtained acid salt of heteropoly acid was first dried at 160 ° C. or higher, more preferably 200 ° C. or higher while flowing dry nitrogen, and the retained water was removed as much as possible. Later, with polar solvent 120-25
0 ° C, preferably 160-200 ° C, pressure 1-15kg
/ Cm ² G for 1 to 50 hours, it is possible to obtain an acid salt of a heteropoly acid having a large proportion of the above mesoporous pores.

Examples of the polar solvent include water-containing or anhydrous organic carboxylic acids and organic carboxylic acid esters. Examples of the organic carboxylic acids or organic carboxylic acid esters include, for example, formic acid, acetic acid, propionic acid,
Examples thereof include organic carboxylic acids such as butyric acid, formic acid esters, organic carboxylic acid esters such as ethyl acetate, propyl acetate, and ethyl propionate. The acid catalyst of the present invention may be used alone or may be used by supporting it on a porous inorganic carrier. Examples of the inorganic carrier include silica, silica-alumina, diatomaceous earth, titania, activated carbon and the like. Further, the acid catalyst of the present invention may be used by adding a metal such as palladium or gold depending on the application.

[0017]

【Example】

Measurement of surface area, pore volume and pore distribution; 3 g of a sample is put in a sample holder and heated at 105 ° C. for 1 hour under vacuum. Then, the sample together with the sample holder was cooled with liquid nitrogen, and the Sorptomatic 199 manufactured by Carlo Erba Co., Ltd.
It was measured by the gas adsorption method using 0.

Measurement of acid amount: A 0.1 g sample was placed in a test tube, 5 ml of benzene was added, and then benzene containing 0.1% of an indicator was added to observe a color change.

Example 1 Commercially available phosphotungstic acid (170.14 g) (manufactured by Wako Pure Chemical Industries, Ltd.) was dissolved in 300 ml of water. Aqueous cesium nitrate solution (cesium nitrate / water = 24.
(36 g / 200 ml) was added dropwise over 3 hours to obtain a white turbid liquid. The cloudy liquid was aged in a water bath at 90 ° C. for 1 hour and then 3
It was resuspended in 00 ml of water, sprayed into a heating furnace, and the water was evaporated to give a white powder. The white powder was dried at 200 ° C. for 3 hours and then tablet-molded to obtain a columnar catalyst having a diameter of 5 mm and a height of 5 mm (hereinafter referred to as a tableting catalyst).

The tableting catalyst thus obtained was treated with acetic acid:
Gas mixed with a volume ratio of nitrogen = 30: 70 has a flow rate of 50 L.
At a temperature of 160 ° C. and a pressure of 8 kg / cm ² G for 10
Time processing was performed. The specific surface area is 90 m ² / g, the pore volume is 0.11 cc / g, and the ratio of pore diameters of 40 Å or more is 50.
%, The amount of acid having H ₀ of 3.3 or less was 2.0 mmol / g.

Example 2 Example 2 was repeated except that phosphotungstic acid was changed to silicotungstic acid. Specific surface area is 85m ² / g,
The pore volume is 0.10 cc / g, the ratio of pore diameters of 40 Å or more is 43%, and the acid amount of H ₀ of 3.3 or less is 2.2 mmo.
1 / g.

Example 3 Example 3 was repeated except that potassium nitrate was used instead of cesium nitrate. Specific surface area 65 m ² / g, pore volume 0,
07 cc / g, ratio of pore size of 40Å or more is 35% H ₀
The acid amount of 3.3 or less was 0.48 mmol / g.

Example 4 Commercially available phosphotungstic acid (manufactured by Wako Pure Chemical Industries) aqueous solution (3
Cesium nitrate aqueous solution (10.
500 ml of 9 wt%) was dropped. The water in the white precipitate deposited here was evaporated, and the remaining clay-like substance was taken out on a petri dish and dried at 180 ° C. for 10 hours under a nitrogen stream. Further, the dried product is resuspended in an equal volume of water,
Dried under nitrogen stream for 20 hours. The dried material was crushed and then tablet-molded to obtain a columnar catalyst having a diameter of 5 mm and a height of 5 mm (hereinafter referred to as a tableting catalyst).

The tableting catalyst thus obtained was first introduced with nitrogen gas at a flow rate of 50 L / h, treated at 220 ° C. and normal pressure for 10 hours, and then the tableting catalyst was mixed with acetic acid: water: nitrogen = 15. :
Gas mixed in a volume ratio of 10:75 was introduced at a flow rate of 50 L / h, and treated at 160 ° C. and a pressure of 8 Kg / cm ² G for 10 hours. The specific surface area is 95 m ² / g and the pore volume is 0.
11cc / g, the ratio of pore size of 40Å or more is 48%, H
_The amount of acid having ₀ of 3.3 or less was 2.5 mmol / g.

Comparative Example 1 Commercially available phosphotungstic acid (170.14 g) (Wako Pure
(Medicinal product) was dissolved in 300 ml of water. Stirring the aqueous solution
While cesium nitrate aqueous solution (cesium nitrate / water = 24.
36 g / 200 ml) was added dropwise over 3 hours to remove the white turbid liquid.
Obtained. Water in white precipitate evaporates, leaving a clay-like substance
Take out on a petri dish and dry in air at 100 ° C for 10 hours.
Dried. The dried product is crushed and then tablet-molded to have a diameter of 5
A columnar catalyst having a height of 5 mm and a height of 5 mm (hereinafter referred to as a tableting catalyst)
You. ) Got. Specific surface area is 105m ^Two / G, the pore volume is
0.13cc / g, the ratio of pore size of 40Å or more is 18
%, H₀ = Acid amount of 3.3 or less is 2.0 mmol / g
Was.

Example 5 3 g of the catalyst prepared in Example 3, 82 g of methacrylic acid, 108 g of benzyl alcohol and 200 g of benzene were placed in a 300 ml autoclave equipped with a magnetic stirrer, and then stirred at 500 rpm while maintaining a bath temperature of 100. ℃
Then, the reaction was carried out for 5 hours while removing the produced water by azeotropic distillation with benzene. As a result, the yield of benzyl methacrylate was 95%.

Comparative Example 2 The same reaction as in Example 5 was carried out except that 3 g of the catalyst prepared in Comparative Example 1 was used. The yield of benzyl methacrylate after 5 hours was 48%.

[0028]

EFFECT OF THE INVENTION An acidic salt of a heteropoly acid having large pores, which is useful as a catalyst, was obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location B01J 35/10 301 B01J 35/10 301J C07C 67/08 C07C 67/08 69/54 69/54 Z // C07B 61/00 300 C07B 61/00 300 (72) Inventor Kenichi Sano No. 2 Nakasu, Oita City, Oita Prefecture Showa Denko Oita Factory

Claims (4)

[Claims] 1. An acid amount having a specific surface area of 10 m ² / g or more, a pore volume of 0.01 cc / g or more, a pore diameter of 40 Å or more and 30% or more of all pores, and an H ₀ of 3.3 or less. 0.1-
An acid catalyst consisting of an acid salt of a heteropoly acid of 3.0 mmol / g. 2. An acid catalyst comprising an acid salt of a heteropolyacid according to claim 1, wherein the heteropolyacid comprises at least one of phosphotungstic acid, silicotungstic acid, phosphomolybdic acid and silicomolybdic acid. 3. The acidic salt of heteropolyacid according to claim 1, wherein the acidic salt of heteropolyacid is previously dried at a temperature of 160 ° C. or higher and then treated with a gaseous polar solvent at 120 ° C. or higher. Manufacturing method. 4. The method for producing an acidic salt of a heteropolyacid according to claim 3, wherein the polar solvent is an organic carboxylic acid or an organic carboxylic acid ester.