JPH08253314A - Production of highly crystalline titanosilicate - Google Patents

Abstract

PURPOSE: To provide a method for producing a crystalline titanosilicate capable of using an aqueous solution of a tetraalkylammonium hydroxide containing an alkali metal mixed therein as an effective raw material. CONSTITUTION: A tetraalkyl orthosilicate in an amount of >=12 equiv. based on 1g atom alkali metal contained in an aqueous solution of a tetraalkylammonium hydroxide is charged into the aqueous solution in the method for producing a crystalline titanosilicate having a pentasil type structure by hydrolyzing the tetraalkyl orthosilicate and a tetraalkyl orthotitanate with the aqueous solution of the tetraalkylammonium hydroxide containing an alkali metal and then carrying out the hydrothermal synthesis.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing highly crystalline titanosilicate. The crystalline titanosilicate obtained in the present invention is a very useful compound as a catalyst for epoxidation of olefins using peroxide as an oxidant and hydroxylation reaction of aromatic compounds.

[0002]

It is known to produce a crystalline titanosilicate by hydrolyzing a mixture of tetraalkyl orthosilicate and tetraalkyl orthotitanate with an aqueous solution of tetraalkylammonium hydroxide and then hydrothermally synthesizing it. This technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 56-96720, Appl. Catal. , 92, 93 (199
2) and Zeolites, 14, 169 (1994).
Etc.

[0003]

However, in the cited method of producing titanosilicate, in order to obtain highly crystalline titanosilicate, it is necessary to use an aqueous tetraalkylammonium hydroxide solution containing no alkali metal as a raw material. is there. For example, according to Zeolites described above, when an extremely small amount of alkali cation is present in the reaction system, titanium does not enter the framework in the titanosilicate, and titanium segregates near the outer surface of the titanosilicate, The crystallinity of the obtained titanosilicate is substantially reduced.

Tetraalkylammonium hydroxide is usually synthesized from tetraalkylammonium bromide and an alkali compound, so that it is inevitable to mix in an alkali. On the other hand, as a method for obtaining an aqueous tetraalkylammonium hydroxide solution containing no alkali metal, an aqueous tetraalkylammonium bromide solution can be produced through a column of anion exchange resin. A large amount of anion exchange resin is required to obtain the compound, which is a problem from the economical point of view.

Therefore, it has been expected to develop a method for producing a crystalline titanosilicate which can use an aqueous solution of tetraalkylammonium hydroxide mixed with an alkali metal as an effective raw material.

The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing a highly crystalline titanosilicate using a tetraalkylammonium hydroxide aqueous solution mixed with an alkali metal as a raw material. That is.

[0007]

[Means for Solving the Problems] The present inventors diligently studied a method for producing crystalline titanosilicate. As a result, tetraalkyl orthosilicate and tetraalkyl orthotitanate are hydrolyzed with an aqueous tetraalkylammonium hydroxide solution containing an alkali metal, and then hydrothermally synthesized to produce a crystalline titanosilicate having a pentasil-type structure. It was found that a highly crystalline titanosilicate can be obtained by charging tetraalkyl orthotitanate at a specific ratio with respect to the alkali metal contained in the tetraalkylammonium hydroxide aqueous solution, and completed the present invention. .

That is, the present invention provides a method for producing a crystalline titanosilicate by hydrolyzing tetraalkylorthosilicate and tetraalkylorthotitanate with an aqueous tetraalkylammonium hydroxide solution containing an alkali metal, and then hydrothermally synthesizing the same. The present invention relates to a method for producing a highly crystalline titanosilicate, which comprises charging tetraalkyl orthotitanate at a ratio of 12 equivalents or more per 1 gram atom of an alkali metal contained in an aqueous solution of tetraalkylammonium hydroxide.

Next, the present invention will be described in more detail.

According to the present invention, the highly crystalline titanosilicate is produced by hydrolyzing tetraalkyl orthosilicate and tetraalkyl orthotitanate with an aqueous tetraalkylammonium hydroxide solution containing an alkali metal, and then hydrothermally synthesizing the same. To be done.

The tetraalkyl orthosilicate used in the present invention is not particularly limited, but examples thereof include tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, tetrapentyl orthosilicate and tetraethyl orthosilicate. Hexyl orthosilicate, tetraheptyl orthosilicate, tetraoctyl orthosilicate, trimethylethyl silicate, dimethyldiethylsilicate, methyltriethylsilicate, dimethyldipropylsilicate, ethyltripropylsilicate and the like can be mentioned. Of these, tetraethyl orthosilicate is preferably used because it is easily available. The tetraalkyl orthosilicate may be either a monomer or an oligomer.

The tetraalkyl orthotitanate used in the present invention is not particularly limited, but examples thereof include tetramethyl orthotitanate, tetraethyl orthotitanate, tetrapropyl orthotitanate, tetrabutyl orthotitanate, tetraoctyl orthotitanate, Trimethylethyl titanate, dimethyldiethyl titanate, methyltriethyl titanate,
Dimethyldipropyl titanate and ethyl tripropyl titanate are mentioned. Of these, tetraethyl orthotitanate and tetrabutyl orthotitanate are preferably used because they are easily available. The tetraalkyl orthotitanate may be either a monomer or an oligomer.

The tetraalkylammonium hydroxide used in the present invention is not particularly limited,
Examples thereof include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide and the like, and tetrapropylammonium hydroxide is preferably used from the viewpoint of easy availability. The above tetraalkylammonium hydroxides can be used not only individually, but also as a mixture of two or more kinds.

It is preferable that the charging ratio of these reaction raw materials when producing the titanosilicate of the present invention is as follows. The amount of tetraalkyl orthotitanate used is at least 12 equivalents, preferably at least 14 equivalents, per gram atom of alkali metal contained in the aqueous tetraalkylammonium hydroxide solution. When the amount of tetraalkyl orthotitanate used is less than 12 equivalents per 1 gram atom of alkali metal contained in the aqueous solution of tetraalkylammonium hydroxide, the resulting titanosilicate has low crystallinity, and epoxidation of olefins and aromatic compounds It does not show sufficient catalytic activity in the hydroxylation reaction. In addition, in this invention, an alkali metal represents lithium, sodium, potassium, rubidium, and cesium. The amount of alkylammonium hydroxide used is 0.1 to 1% with respect to 1 mol of tetraalkyl orthosilicate.
It is 0 equivalent, and preferably 0.2 to 0.60 equivalent. The concentration of the tetraalkylammonium hydroxide aqueous solution is 3 to 50% by weight, preferably 5 to 40% by weight.

The hydrolysis reaction temperature of the present invention is -20 to
The temperature is 60 ° C, preferably -10 to 40 ° C. When the reaction temperature is low, the reaction rate is too low, which is industrially disadvantageous. On the other hand, when the reaction temperature exceeds 60 ° C., the hydrolysis of the tetraalkyl orthotitanate is accelerated and the titania may be segregated. The reaction time is not particularly limited, but is 1
It is 0 minutes to 100 hours, preferably 30 minutes to 50 hours. A solvent can be used if necessary during hydrolysis. Examples of the solvent include alcohols such as methanol, ethanol, propanol, butanol and octanol, ketones such as acetone and methyl ethyl ketone, and ethers such as diethyl ether, tetrahydrofuran and dimethoxyethane.

In the present invention, if a uniform hydrolysis product can be obtained in the hydrolysis reaction, the mixing order and mixing method of the reaction raw materials of the tetraalkyl orthosilicate, the tetraalkyl orthotitanate and the aqueous solution of tetraalkylammonium hydroxide are not particularly limited. Not limited. For example, all of the above compounds may be mixed at once, or an aqueous solution of alkylammonium hydroxide may be added dropwise to a mixture of tetraalkyl orthosilicate and tetraalkyl orthotitanate. Alternatively, an aqueous solution of alkyl ammonium hydroxide may be added to tetraalkyl orthosilicate, and then tetraalkyl orthotitanate may be added. The alcohol by-produced by hydrolysis does not necessarily have to be removed, but it is preferable to reduce the amount by heating in advance.

The hydrolyzed product obtained as described above is subjected to hydrothermal synthesis by adding water if necessary. The amount of water used for hydrothermal synthesis is adjusted to 15 to 100 equivalents, preferably 25 to 80 equivalents, relative to 1 mol of silicon atom, in combination with water added during the hydrolysis reaction. If the amount of water added is less than 15 equivalents relative to 1 mol of silicon atoms, titania tends to segregate, and the crystallinity of titanosilicate becomes substantially low. On the other hand, when the amount of water added exceeds 100 equivalents to 1 mol of silicon atoms, the yield of the homogeneous mixed solution obtained by hydrolysis is low and economically disadvantageous, which is not preferable.

In the hydrothermal synthesis reaction, this mixed solution is heated in a closed container under temperature conditions of 60 to 300 ° C., preferably 100 to 200 ° C., for 1 to 100 hours, preferably 6 to 5
It is carried out by holding this temperature for 0 hours.
At this time, the pressure can be applied either by self pressure or under pressure, but usually under pressure. It is not always necessary to stir the reaction system, and crystallization proceeds sufficiently even in a stationary state.

The solid powder crystallized by the hydrothermal synthesis treatment in this way is thoroughly washed with ion-exchanged water and then subjected to a firing treatment. The temperature of the baking treatment is 300 to 700 ° C, preferably 350 to 600 ° C. The firing time is not particularly limited, but the highly crystalline titanosilicate of the present invention can be produced by performing a firing treatment for 1 to 50 hours, preferably 2 to 20 hours.

The titanosilicate according to the present invention is a crystal having extremely high thermal stability and has a pentasil type structure similar to ZSM-5, ZSM-11 and the like.

The highly crystalline titanosilicate produced according to the present invention has a use as a catalyst for epoxidation of olefins and hydroxylation reaction of aromatic compounds.

[0022]

EXAMPLES The present invention will be described in more detail below with reference to examples, but these examples show an outline of the present invention, and the present invention is not limited to these examples. . Example 1 Tetraethyl orthotitanate 43.2 in a 1000 ml four-necked flask equipped with a thermometer and a stirrer.
g and then 197 g of tetraethyl orthosilicate were added and mixed under a nitrogen stream. After cooling this mixed solution to 0 ° C., it contains K of 1300 ppm and Na of 25 ppm.
Weight% tetrapropylammonium hydroxide aqueous solution 346
g was added dropwise using a feed pump over 1 hour, and the mixture was further stirred at room temperature for 1 hour. After stirring, the mixture became a homogeneous solution. This four-necked flask was heated to about 90 ° C in an oil bath to distill off the ethanol produced by hydrolysis (2
03g).

Ion-exchanged water 59 was added to the mixture removed by distillation.
After adding 3 g, 450 ml of the mixture was put into a pressure-resistant Hastelloy reaction vessel having an internal volume of 500 ml equipped with a thermometer and a stirrer, and the temperature was raised to 170 ° C. under self-pressure for 2 hours.
Stir for hours. Centrifuge the contents of the autoclave,
It was thoroughly washed with ion-exchanged water at 65 ° C. The white powder obtained was dried at 90 ° C. for 15 hours and then calcined at 550 ° C. for 5 hours to obtain 21.5 g of titanosilicate. X-ray diffraction (X
The main peaks by RD) and the intensity ratio of each peak are shown in Table 1. This crystal structure was a pentasil-type structure and showed high crystallinity.

[0024]

[Table 1]

Next, in order to examine the catalytic performance of this titanosilicate, an epoxidation reaction of propylene was carried out. To this titanosilicate, tetraamminepalladium chloride (I
I) An aqueous solution was added to titanosilicate so that the weight of palladium atoms would be 0.5% by weight, and the mixture was stirred at room temperature for 1
Stir and mix for hours. After evaporating the suspension to dryness, 1
Gas phase reduction was carried out at 50 ° C. for 1 hour under a hydrogen flow of 17% by volume diluted with nitrogen to obtain a Pd-supported titanosilicate catalyst.
Internal volume 1 equipped with a thermometer, stirrer and gas inlet
In a glass-made normal pressure semi-batch reactor of 00 ml, 1.0 g of Pd-supporting titanosilicate as a catalyst and 60 ml of water as a solvent were put and stirred. Propylene, oxygen, and hydrogen are added here to 60 mmol / hr and 40 mmol / hr, respectively.
hr, 40 mmol / hr, diluted with nitrogen, and volume hourly space velocity (GHSV) 7970 hr.
^The temperature was adjusted to ^-1 (20 ° C) and the temperature was kept at 45 ° C to carry out the epoxidation reaction of propylene. The outlet gas was led to an n-butanol trap in an ice bath and the entrained propylene oxide was collected in the trap. The reaction product was analyzed by gas chromatography. 4 hours after the start of the reaction, the conversion rate of propylene as a raw material was 4.5 mol%, and propylene oxide was 29.50 per unit time and unit catalyst weight.
4 g had been produced. Table 2 shows the results.

[0026]

[Table 2]

Example 2 Tetraethylorthotitanate 39.9 was placed in a 1000 ml four-necked flask equipped with a thermometer and a stirrer.
g and then 197 g of tetraethyl orthosilicate were added and mixed under a nitrogen stream. After cooling this mixed solution to 0 ° C., it contains K of 1300 ppm and Na of 25 ppm.
Weight% Tetrapropylammonium Hydroxide Aqueous Solution 346
g was added dropwise using a feed pump over 1 hour, and the mixture was further stirred at room temperature for 4 hours. After stirring, the mixture became a homogeneous solution. The four-necked flask was heated to about 90 ° C. in an oil bath, and ethanol generated by hydrolysis was distilled off.

Ion-exchanged water 59 was added to the mixture removed by distillation.
After adding 3 g, 450 ml of the mixture was put into a pressure-resistant Hastelloy reaction vessel having an internal volume of 500 ml equipped with a thermometer and a stirrer, and the temperature was raised to 170 ° C. under self-pressure for 2 hours.
Stir for hours. Centrifuge the contents of the autoclave,
It was thoroughly washed with ion-exchanged water at 65 ° C. The white powder obtained was dried at 90 ° C. for 15 hours and then calcined at 550 ° C. for 5 hours to obtain 20.2 g of titanosilicate.

An aqueous solution of tetraamminepalladium (II) chloride was added to this titanosilicate so that the weight of palladium atoms was 0.5% by weight with respect to the titanosilicate, and the mixture was stirred and mixed at room temperature for 1 hour. The suspension was evaporated to dryness and then diluted with nitrogen for 1 hour at 150 ° C. 17
Gas phase reduction was performed under a flow of volume% hydrogen to obtain a Pd-supported titanosilicate catalyst. A glass atmospheric pressure semi-batch reactor with an internal volume of 100 ml equipped with a thermometer, a stirrer, and a gas blowing port was charged with 1.0 parts of Pd-supporting titanosilicate as a catalyst.
g and 60 ml of water as a solvent were added and stirred. 60 mmol / h of propylene, oxygen and hydrogen respectively
r, 40 mmol / hr, 40 mmol / hr, and this was diluted with nitrogen, and the volume time space velocity (GHS
V) The temperature was adjusted to 7970 hr ⁻¹ (20 ° C.) and the temperature was kept at 45 ° C. to carry out the epoxidation reaction of propylene.
The outlet gas was led to an n-butanol trap in an ice bath and the entrained propylene oxide was collected in the trap.
The reaction product was analyzed by gas chromatography. 4 hours after the start of the reaction, 22.5 g of propylene oxide was produced per unit time and unit catalyst weight. The results are also shown in Table 2.

Example 3 A titanosilicate was synthesized in the same manner as in Example 1 except that 108 g of tetraethyl orthotitanate was used.
Furthermore, the epoxidation reaction of propylene was performed. The results are also shown in Table 2.

Comparative Example 1 Titanosilicate was synthesized in the same manner as in Example 1 except that 21.6 g of tetraethylorthotitanate was used, and propylene was epoxidized. The results are also shown in Table 2. From the X-ray diffraction, the crystallinity of this titanosilicate was low, and the epoxidation activity of propylene was extremely low.

Comparative Example 2 A titanosilicate was synthesized in the same manner as in Example 1 except that 6.5 g of tetraethyl orthotitanate was used.
Furthermore, the epoxidation reaction of propylene was performed. The results are also shown in Table 2.

Example 4 252 g of ion-exchanged water added to the mixture removed by distillation
Titanosilicate was synthesized in the same manner as in Example 1 except that it was used, and the epoxidation reaction of propylene was further performed. The results are shown in Table 3.

[0034]

[Table 3]

Example 5 A titanosilicate was synthesized in the same manner as in Example 2 except that 270 g of an aqueous tetrapropylammonium hydroxide solution and 650 g of ion-exchanged water were used, and an epoxidation reaction of propylene was performed. The results are also shown in Table 3.

Comparative Example 3 Titanosilicate was synthesized in the same manner as in Example 2 except that 424 g of an aqueous tetrapropylammonium hydroxide solution and 520 g of ion-exchanged water were used, and the epoxidation reaction of propylene was performed. The results are also shown in Table 3.

Comparative Example 4 A titanosilicate was synthesized in the same manner as in Example 2 except that 563 g of a tetrapropylammonium hydroxide aqueous solution and 379 g of ion-exchanged water were used, and the epoxidation reaction of propylene was further carried out. The results are also shown in Table 3.

Examples 6 and 7 In Example 6, 600 ppm of K and 220 ppm of Na were used.
An aqueous solution of tetrapropylammonium hydroxide containing 5.5 ppm of K and 725 ppm of Na in Example 7.
A titanosilicate was synthesized in the same manner as in Example 2 except that the contained tetrapropylammonium hydroxide aqueous solution was used, and the epoxidation reaction of propylene was further performed. The results are also shown in Table 3.

[0039]

According to the present invention, a highly crystalline titanosilicate can be produced even when an aqueous tetraalkylammonium hydroxide mixed with an alkali metal is used as a raw material.

Claims (1)

[Claims] 1. A method for producing a crystalline titanosilicate having a pentasil-type structure by hydrolyzing tetraalkyl orthosilicate and tetraalkyl orthotitanate with an aqueous tetraalkylammonium hydroxide solution containing an alkali metal and then hydrothermally synthesizing the same. 2. A method for producing a highly crystalline titanosilicate, which comprises charging tetraalkyl orthotitanate at a ratio of 12 equivalents or more per 1 gram atom of an alkali metal contained in an aqueous solution of tetraalkylammonium hydroxide.