JP2000254512A - Solid acid catalyst and preparation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a solid acid catalyst having high activity and no corrosiveness. SOLUTION: Silicate having meso pores and containing gallium (solid acid catalyst) is obtained by using 8-30C alkyltrimethylammonium as a template to introduce gallium into crystalline silicate. Gallium may be substituted with a part of silicate or may be supported on silicate. This solid acid catalyst is useful as a Lewis acid catalyst, for example, as an acylating or alkylating reaction catalyst due to Friedel-Crafts reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel solid acid catalyst useful for isomerization reaction, Friedel-Frafts reaction, polymerization reaction and the like, and a method for preparing the same.

[0002]

2. Description of the Related Art Conventionally, various acid catalysts have been industrially used. For example, metal halides (such as aluminum chloride) are commonly used as Lewis acid catalysts.
However, in this method, a waste catalyst containing a large amount of metal halide is generated, and it is difficult to dispose or treat the waste catalyst.
In addition, metal halides have high water absorption, and therefore have low industrial handling properties. Furthermore, since metal halides are corrosive, it is necessary to use a reactor having high corrosion resistance, which increases the cost. Further, a complicated operation is required for separating the catalyst.

On the other hand, in order to solve these problems, a solid acid catalyst, for example, a catalyst in which BF ₃ is supported on a carrier (such as alumina) and a crystalline iron silicate having mesopores have been proposed. However, these solid acid catalysts have low activity and are difficult to use industrially.

[0004]

Accordingly, an object of the present invention is to provide a highly active solid acid catalyst and a method for preparing the same.

Another object of the present invention is to provide a solid acid catalyst which is non-corrosive and easy to separate and recover, and a method for preparing the same.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object. As a result, when gallium is introduced into a crystalline silicate-based solid catalyst having mesopores, it has no corrosive property and high activity. It was found that a solid acid catalyst having the following formula was obtained, and the present invention was completed.

That is, the solid acid catalyst of the present invention is composed of a crystalline silicate having mesopores and containing gallium, and the gallium is substituted with a part of the silicate or supported on the silicate. Can be contained. Such solid acid catalysts can be used for various acid catalysts, for example, Lewis acid catalyzed reactions (such as Friedel-Crafts reactions for acylation and alkylation).

The solid acid catalyst according to the present invention is a method for preparing a crystalline silicate having mesopores and into which gallium has been introduced, wherein the _C8-30 alkyltrimethylammonium salt is used as a template for forming mesopores. Can be prepared.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The solid acid catalyst of the present invention has pores and is formed of gallium-containing crystalline silicate. The average pore size of the pores can be selected from a range that does not impair the catalytic activity, for example, a range of about 1.3 to 10 nm. The average pore diameter of the pores usually belongs to the category of mesopores.

The crystalline silicate having pores (particularly, mesopores) can be composed of, for example, a mesoporous molecular sieve having a hexagonal pore structure (hexagonal structure) in which pores (particularly, mesopores) are arranged substantially regularly. A crystalline silicate having mesopores is known as "MCM-41". The average pore size (2r) can be calculated based on the surface area (S) of the solid catalyst and the average pore volume (Vp), and the mesoporous molecular sieve structure can be confirmed by X-ray diffraction.

The surface area of the solid acid catalyst is in a wide range that does not impair the catalytic activity, for example, 100 to 2000 m ² / g.
Can be selected from the range of about 200 to 1500 m ²
/ G, preferably about 300 to 1200 m ² / g (eg, about 500 to 1,000 m ² / g). In addition,
The surface area of the catalyst can be measured by an adsorption method using nitrogen (nitrogen adsorption method). The pore volume of the solid acid catalyst is, for example, about 0.1 to 5 ml / g, preferably 0.2 to 2.
It is about 5 ml / g (for example, 0.3 to 1 ml / g).

The solid acid catalyst of the present invention contains silicate (particularly crystalline silicate) and gallium as main components. The gallium-containing form is not particularly limited. For example, a form in which gallium is supported on the crystalline silicate (that is, gallium-supported crystalline silicate), a form in which part of the silicate is substituted with gallium (that is, crystalline gallium silicate) ). In addition, whether the silicon of the silicate is replaced by gallium,
By EXAFS analysis, it found in Ga ₂ O ₃ Ga-
The determination can be made based on whether the peak derived from the Ga bond disappears and the peak derived from the Ga—O bond is observed.

In the solid acid catalyst, the ratio of silicon to gallium can be selected from a range that does not impair the catalytic activity, for example, a range of about 10 to 120 mol of silicon with respect to 1 mol of gallium. On the other hand, silicon is 12 to 120 mol, preferably 13 to 50 mol, more preferably 15 to 40 mol (for example, 15 to 30 mol).
It is about. When the proportion of silicon is small, the thermal stability of the solid acid catalyst decreases, and when the proportion of silicon is large, the catalytic activity tends to decrease with a decrease in the acid amount and acid strength of the catalyst.

The solid acid catalyst of the present invention forms a Lewis acid type catalyst. That is, when pyridine is adsorbed on the solid acid and the infrared absorption spectrum is measured, the ratio of the absorption region A _L corresponding to the Lewis acid type acid point and the absorption region A _B corresponding to the Bronsted type acid point is: _{A L / A B = 80 /} 20~100
/ 0 (area ratio), preferably 90/10 to 100 /
0 (area ratio), more preferably 95/5 to 99 /
It is about 1 (area ratio). Absorption range A _L corresponding to the Lewis acid type acid point is usually wavenumber 1447~1460cm ^-1 (e.g., 1455~1460cm ^-1), especially 1457cm
^-1 is the absorption zone having a main peak, the absorption region A _B corresponding to Bronsted-type acid point, usually wavenumber 1530-1
560 cm ^-1 (for example, 1540-1550 cm ^-1 ),
In particular, it is an absorption region having a main peak at 1545 cm ^-1 .

The acid amount of the solid acid catalyst can be measured by a method of adsorbing ammonia (NH ₃ ) gas on the catalyst and measuring the amount of adsorption (gas base adsorption method, NH ₃ -TPD).
For example, 0.1 meq / g or more, preferably 0.2 meq / g
q / g or more (for example, about 0.2 to 0.8 meq / g)
It is. The acid strength of the solid acid catalyst can be calculated by measuring the desorption temperature of the adsorbed NH _{3 in} the gas base adsorption method.

(Method for Preparing Solid Acid Catalyst) The solid acid catalyst of the present invention has pores (particularly, mesopores) and can be prepared by introducing gallium into a crystalline silicate. In this method, it is important to use an alkyltrimethylammonium salt as a template for forming the pores. That is, as long as pores are formed using the template and gallium is introduced into the silicate,
The method for preparing the solid acid catalyst of the present invention is not particularly limited.

A specific method for preparing a solid acid catalyst is as follows.
(1) Gallium is introduced by heating the silica component and the gallium component in the presence of the template,
And a method of obtaining a crystalline silicate having pores (crystalline gallium silicate). (2) gallium is introduced by supporting a gallium component on the crystalline silicate having pores prepared using the template. And a method for obtaining a crystalline silicate (gallium-supporting crystalline silicate).

In the above method (1), the solid acid catalyst comprises:
In general, the template can be used to carry out a hydrothermal synthesis method in which a silica component and a gallium component are heat-treated in an aqueous solvent system, and this reaction can be carried out at normal pressure or under pressure.

As the silica component, various silicon-containing compounds capable of forming a crystalline silicate, for example, silica alkoxide (tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, trimethoxymethylsilane, etc.), silicate (silicone) Acid soda), silica sol, colloidal silica, and the like. Preferred silica components include crystalline silicates, for example, colloidal silica.

As the gallium component, a water-soluble gallium compound is usually used, for example, a salt of gallium and an inorganic acid (such as gallium nitrate (Ga (NO ₃ ) ₃ )). A gallium compound having a valence of 1 to 3 (especially, a valence of 3) is used, and the amount of the gallium component to the silica component can be selected according to the ratio of silicon to gallium in the solid acid catalyst.

The alkyltrimethylammonium salt used in the present invention has a higher (or long-chain) alkyl group having 8 to 30 carbon atoms and three methyl groups. The average pore size of the solid acid catalyst can be adjusted by the carbon number of the higher alkyl group.
C _{8- 30} alkyl group as higher alkyl groups may be straight-chain or branched-chain alkyl group, for example, octyl group,
Examples include decyl, dodecyl, tetradecyl, pentadecyl, hexadecyl, octadecyl, icosyl, and docosyl groups. Preferred higher alkyl groups include C _10-25 alkyl groups (eg, C _10-20 alkyl groups), especially C _12-18 alkyl groups (eg, C _12-16 alkyl groups).

Examples of the alkyltrimethylammonium salt include salts with halogen ions (salts with chloride ions, bromine ions, etc.). These C _8-30
The alkyltrimethylammonium salts can be used alone or in combination of two or more.

As the aqueous solvent, water is usually used,
If necessary, a hydrophilic or water-soluble solvent (alcohols, ketones, ethers, carboxylic acids, etc., particularly alcohols such as methanol) compatible with water may be used in combination. These solvents can be used alone or in combination of two or more.

The hydrothermal synthesis temperature of the silica component and the gallium component is, for example, about 60 to 300 ° C., preferably 80 to 300 ° C.
It is about 200 ° C (for example, 80 to 120 ° C). The pressure can be appropriately selected according to the heating temperature, and can be appropriately selected usually from, for example, a range of about 1 to 10 atm, preferably about 1 to 5 atm. The heating time depends on the reaction temperature, for example, about 1 hour to 30 days, preferably 5 hours to
You can select from a range of about 10 days. The reaction can be carried out with or without stirring.

In the course of the reaction, if necessary, the pH of the reaction system is, for example, about 8 to 12 (preferably 10 to 1).
2). The pH can be adjusted, for example, by continuously or intermittently adding an acid or alkali solution (particularly an acid solution, for example, an acetic acid solution) during the heating process.

As described above, by heating the silica component and the gallium component in the presence of an alkyltrimethylammonium salt (particularly, a C _8-30 alkyltrimethylammonium salt) as a template agent, a gallium-containing silicate (particularly, Gallium silicate). The generated gallium-containing silicate may be subjected to a conventional purification step (washing, drying, etc.) to remove impurities (salt component, water, etc.). For example, by washing gallium-containing silicate with water, water-soluble impurities such as salt components (eg, halogen ions) can be removed.

Further, under an atmosphere containing oxygen such as air, at an appropriate temperature, for example, about 300 to 700 ° C. (for example,
By baking the crystalline gallium silicate at about 00 to 600 ° C.), organic components such as a template agent can be removed.

In the purified gallium-containing silicate (crystalline or crystalline gallium silicate), an alkali metal or an alkaline earth metal derived from a silica component may be further subjected to ion exchange with ammonium ions. The catalyst can be highly activated by baking after ion exchange with ammonium ions. Ion exchange can be usually performed by immersing gallium-containing silicate in an aqueous solution containing ammonia or an ammonium salt (an aqueous solution of ammonium nitrate, an aqueous solution of ammonium sulfate, an aqueous solution of ammonium chloride, an aqueous solution of ammonium bromide, etc.) and stirring or standing. Firing is performed, for example, in an appropriate atmosphere (for example,
Under oxygen-containing atmosphere or inert gas atmosphere)
It can be performed at about 00 ° C, preferably about 400 to 600 ° C.

In the method (2), the gallium component is supported or deposited by a conventional method, for example, (2a)
A method of dipping a silicate (usually in a granular form) in an aqueous solvent containing a gallium compound, (2b) a method of spraying an aqueous solvent containing a water-soluble gallium compound in a silicate (usually in a granular form), 2c) A method of adding an acid or an alkali to a mixed solution containing a silicate and a gallium component to deposit the gallium component on the silicate can be exemplified. Note that, as the silicate, a crystalline silicate having pores prepared using the template can be used. The gallium-supported crystalline silicate can be prepared by washing and drying the silicate on which the gallium component is supported, if necessary, and firing it in the same manner as described above.

The form of the solid acid catalyst of the present invention is not particularly limited, and may be, for example, in the form of powder, granules, pellets, flakes, rods, flakes, tablets, honeycombs, or the like. Further, the solid acid catalyst may be a molded article having a predetermined shape formed by a molding method such as pressure molding or extrusion molding.

The solid acid catalyst of the present invention thus obtained has high catalytic activity and can greatly reduce corrosiveness. Further, since the catalyst is in a solid form, separation and recovery from the reaction mixture are easy. Therefore, even if the amount of the catalyst is reduced or the reaction temperature is lowered, the target compound can be industrially advantageously produced in a high yield.

The solid acid catalyst of the present invention can be used in various acid catalyzed reactions (particularly Lewis acid catalyzed reactions), for example, Friedel-Crafts reaction (acylation reaction utilizing Friedel-Crafts reaction, alkylation reaction, etc.), esterification Reaction (such as esterification reaction between carboxylic acid or its reactive derivative and alcohol), isomerization reaction (such as isomerization reaction from linear hydrocarbon to branched chain hydrocarbon), acetalization reaction, and polymerization reaction (ethylene and propylene) It is useful as a catalyst in polymerization of vinyl compounds, dienes and the like. Further, the solid acid catalyst of the present invention can be used for any reaction system of a liquid phase or a gas phase.

The reaction using the solid acid catalyst of the present invention can be carried out by a conventional method. For example, an acylation reaction by the Friedel-Crafts reaction involves reacting a reactant [eg, an aromatic compound (eg, a hydrocarbon such as benzene, toluene, or naphthalene)] with an acylating agent (typically, a carboxylic acid halide or a carboxylic acid anhydride). , Etc.). In the acylation reaction, when the solid acid catalyst of the present invention is used, the catalyst has a high catalytic activity. Preferably 2
(About 0 to 60 ° C.). Also, in an alkylation reaction utilizing the Friedel-Crafts reaction, an aromatic agent is efficiently used by using an alkylating agent (alkyl halide, alkene, alkyne, alcohol, ether, ester, etc.) instead of the acylating agent. Sexual compounds can be alkylated.

[0034]

According to the present invention, since the solid acid catalyst is composed of gallium-containing crystalline silicate having pores, a high catalytic activity can be imparted to the solid acid catalyst. Further, since it does not substantially contain a halide, it has little corrosiveness and is easily separated and recovered from the reaction mixture.

[0035]

The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 (Preparation of catalyst) 13.1 g of tetradecyltrimethylammonium bromide (template agent) and colloidal silica (Ludox-40, manufactured by DuPont, silica content:
220 g of an aqueous solution containing 33 g of 40% by weight) and 3.0 g of gallium nitrate were added to a 500 ml polypropylene bottle, and the mixture was allowed to stand at 100 ° C. for 5 days in an autoclave to perform a hydrothermal synthesis reaction. The pH of the reaction system is about 1
To maintain 1, a 5N aqueous acetic acid solution was added every 24 hours. After the completion of the reaction, the reaction mixture was cooled, the reaction mixture was taken out of the autoclave, washed with water until the residual bromide ion disappeared, and dried at 130 ° C. The resulting crystalline product was calcined at 500 ° C. in air to remove residual tetradecyltrimethylammonium bromide. 1 g of the powder crystal obtained by firing was
It was immersed in a prescribed ammonium nitrate aqueous solution (100 ml) and immersed at room temperature (about 20 ° C.) for 24 hours to perform ion exchange treatment. After washing with water, the powder crystals were dried at 100 ° C. further,
By baking in air at 450 ° C. for 5 hours, crystalline gallium silicate having mesopores was obtained.

The structure of the crystalline gallium silicate having mesopores was confirmed by X-ray diffraction.
Analytical peaks were observed at °, 4.49 ° and 4.94 °, confirming that the hexagonal structure had regularity. The surface area of the solid acid catalyst obtained by the nitrogen adsorption method was 864 m ^2.
/ G, the pore volume was 0.57 ml / g, and the pores were mesopores having an average pore diameter (average pore diameter) of 2.4 nm.

In the EXAFS analysis of the solid acid catalyst, there was no peak derived from Ga—Ga bond, and Ga—O
Only the peak derived from the bond was observed, confirming that gallium was incorporated into the silica network. The position of each binding peak was determined based on the peak position of Ga ₂ O ₃ .

Further, in order to identify the type of acid sites and to examine the ratio of acid sites, pyridine was adsorbed on a solid acid catalyst at room temperature, and then pyridine physically adsorbed was removed by vacuum degassing at 100 ° C. An infrared absorption spectrum (IR) was measured. That is, the area ratio between the absorption peak of pyridinium ion adsorbed at the Lewis acid-type acid site (1545 cm ^-1 ) and the absorption peak of pyridinium ion adsorbed at the Bronsted acid-type acid site (1457 cm ^-1 ) was calculated. As a result, the ratio between Lewis acid type acid points and Bronsted type acid points was 97/3 (area ratio). NH ₃ -TP
The acid amount of the solid acid catalyst measured by Method D is 0.51 me
g / g.

(Alkylation by Friedel-Crafts reaction) In a 50 ml flask equipped with a stirrer, benzene 7.
8 g (100 mmol) and 668 mg of benzyl chloride
(5 mmol) and 30 mg of the solid acid catalyst were reacted by stirring at 40 ° C. for 2 hours under a nitrogen stream. When the amount of the generated diphenylmethane was measured by gas chromatography, it was found that diphenylmethane was 44%.
Mole%.

Comparative Examples 1-3 Crystalline silicates having mesopores were obtained in the same manner as in Example 1 except that gallium nitrate was not used (Comparative Example 1). Further, in the same manner as in Example 1 except that aluminum nitrate or iron nitrate was used instead of gallium nitrate, crystalline aluminosilicate having mesopores (Comparative Example 2),
A crystalline iron silicate having mesopores was obtained (Comparative Example 3).

When the obtained crystalline silicate, crystalline aluminosilicate or crystalline iron silicate was used in the alkylation reaction by the Friedel-Crafts reaction in Example 1, none of the reactions proceeded.

Examples 2-6 Crystalline gallium silicates (Si / Ga = 14-63 mol%) having different gallium contents were prepared in the same manner as in Example 1 except that the amount of gallium nitrate used was adjusted. did. Table 1 shows the gallium content and catalytic activity (yield of diphenylmethane) of the obtained solid acid catalyst.

[0044]

[Table 1]

Examples 7 and 8 Mesoporous crystalline silicate 1 obtained in Comparative Example 1
g was impregnated with a 0.3% by weight solution of gallium nitrate in methanol. After the impregnation, the solid acid catalyst was dried at 100 ° C. and calcined at 500 ° C. to prepare a solid acid catalyst having a different amount of gallium (3.1% by weight of gallium, 5.9% by weight). Table 2 shows the gallium content and catalytic activity (yield of diphenylmethane) of the obtained solid acid catalyst.

[0046]

[Table 2]

Comparative Example 4 A gallium-supported amorphous silicate was prepared in the same manner as in Example 7 except that amorphous silica was used instead of the crystalline silicate. When used for the alkylation reaction by the Friedel-Crafts reaction, the yield of diphenylmethane was 0.1 mol%.

Examples 9 to 11 Solid acid catalysts (crystalline gallium silicate) were prepared in the same manner as in Example 8, except that alkyltrimethylammonium bromide having a different number of carbon atoms in the alkyl group was used as the template agent. In addition, hexadecyltrimethylammonium bromide (Example 9), tetradecyltrimethylammonium bromide (Example 10), or decyltrimethylammonium bromide (Example 11) was used as a template agent.

Table 3 shows the number of carbon atoms in the alkyl group of the template agent and the catalytic activity (yield of diphenylmethane) of the obtained crystalline gallium silicate.

[0050]

[Table 3]

Example 12 and Comparative Example 5 (Acylation by Friedel-Crafts Reaction) Using the crystalline gallium silicate obtained in Example 1 and the crystalline iron silicate catalyst obtained in Comparative Example 3, 2-methoxy Acetylation of naphthalene was performed. That is, 5 with stirrer
In a 0 ml flask, add nitrobenzene 7.1 as a reaction solvent.
7 g and 2-methoxynaphthalene 5 mmol (790 m
g), 1.2 mmol of acetyl chloride (94 m
g), 80 mg of a solid acid catalyst was charged, and reacted at a reaction temperature of 40 ° C. for 12 hours under a nitrogen stream to obtain the yield of acetylated methoxynaphthalene (acetylated product) and the 1-, 6-, and 8-positions of methoxynaphthalene. When the selectivity of acetylmethoxynaphthalene having an acetyl group substituted at the -position was measured by gas chromatography, the following results were obtained.

Example 12: The solid acid catalyst of Example 1 was used. The yield of acetylated product was 55 mol%. The production ratio of acetylated product: The production ratio of acetylated product at 1-position was 40%. The production ratio of acetylated product at 6-position was 47%. Comparative Example 5: Use of the solid acid catalyst of Comparative Example 3 Yield of acetylated product: 33 mol% Production ratio of acetylated product: Production ratio of 1-acetylated product: 66% Production ratio of 6-acetylated product: 13% 19% 8% acetylated product 15%

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Claims (6)

[Claims] 1. A solid acid catalyst having mesopores and comprising gallium-containing crystalline silicate. 2. The solid acid catalyst according to claim 1, wherein gallium is contained by substitution with a part of the silicate or by loading on the silicate. 3. The solid acid catalyst according to claim 1, which is a Lewis acid catalyst. 4. The solid acid catalyst according to claim 1, which is a Friedel-Crafts reaction catalyst. 5. The solid acid catalyst according to claim 1, which is a catalyst for acylation or alkylation reaction by Friedel-Crafts reaction. 6. A method for preparing a solid acid catalyst having a mesopore and comprising a gallium-introduced crystalline silicate, wherein the _C8-30 alkyltrimethylammonium is used as a template for forming the mesopore. A method for preparing a solid acid catalyst using a salt.