JPH02302314A - Preparation of crystalline titanoaluminosilicate - Google Patents

Abstract

PURPOSE:To highly homogeneously disperse Ti and Al in a zeolite crystal by subjecting a specific aluminosilicate and a titanium alkoxide to an aqueous thermal synthetic reaction in the presence of an alkyl ammonium hydroxide. CONSTITUTION:(A) An aluminosilicate (e.g. clinoptilolite) having a silica/alumina molar ratio of >=30 and (B) a titanium alkoxide (e.g. tetramethylorthotitanate) in an ratio of 0.5 to 300 (molar ratio) based on the SiO2 in the component A are hydrolyzed in water in an amount of 10 to 200 (molar ratio) based on the SiO2 in the component A at 0 to 200 deg.C for 0.1 to 20hr in the presence of (C) an alkyl ammonium hydroxide (e.g. tetrapropyl ammonium hydroxide) in an amount of 0.5-10 (molar ratio) based on the SiO2 in the A component while removing the by-produced alcohol and subsequently subjected to an aqueous thermal synthetic reaction at 60 to 300 deg.C for 1 to 100hr, followed by washing the resultant solid crystal powder with ion-exchanged water and finally heat- treated at 300 to 700 deg.C for 2 to 20hr.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing crystalline titanoaluminosilicate. More specifically, the present invention relates to a novel method for producing titanoaluminosilicate having porous three-dimensional crystals in which titanium oxide is almost uniformly distributed among aluminum and silicon oxides.

[Conventional technology]

Traditionally, zeolite refers to crystalline aluminosilicate in a narrow sense. However, in recent years, compounds having a structure in which all the aluminum in zeolite is replaced with other metal elements, ie, substances called metallosilicates, have been synthesized. Such metallosilicates also have a crystal structure similar to that of conventional aluminosilicates, and are recognized as a type of zeolite in a broad sense. The main feature of aluminosilicate and silicade is a solid acid catalytic function based on the aluminum element, whereas the feature of metallosilicate is that each has a unique catalytic function derived from the metal element contained. For example, examples of the application of metallosilicate to catalytic reactions include oxidation reactions and ammoxidation reactions.

Recently, it has also become known to synthesize metallosilicates in which part of the aluminum is replaced by other elements, ie, the metallosilicates contain aluminum and other different metal elements. Such composite metallosilicates have both the solid acid catalytic function of aluminosilicate and the catalytic functions specific to other metal elements, and are therefore expected to provide multifunctional catalysts.

Furthermore, it is expected that the interaction between the two elements will improve the catalytic function and produce new effects. In addition, it has the potential to provide new materials for applications other than catalysts, such as ion exchangers and adsorbents, and has great industrial expectations.

Incidentally, it is believed that titanoaluminosilicate, that is, zeolite having a structure in which part of the aluminum in zeolite is replaced with titanium, has already been synthesized at the same time as titanosilicate is prepared. That is, water glass, sodium silicate, silica gel, and Aerosil are usually used as silica sources for titanosilicate synthesis, but since these contain trace amounts of aluminum as impurities, these silica When titanosilicate is synthesized using the source, titanoaluminosilicate is substantially produced.

However, what is actually obtained is often a mixture of aluminosilicate and titania rather than titanosilicate.

In addition, attempts have been made to replace part of the aluminum in aluminosilicate with titanium (Japanese Patent Application Laid-open No. 1983-1999).
No. 2695, JP-A-57-11818, JP-A-58-
No. 74521). However, in this method, a silica source (water glass, sodium silicate, etc.), an aluminum source (aluminum alkoxide, etc.), and a titanium source (titanium alkoxide, etc.) are added to an alkaline aqueous solution, so titania precipitates are likely to form in the alkaline aqueous solution. Even when this mixture is hydrothermally synthesized, titanium is not incorporated into the zeolite crystal lattice and tends to become amorphous titania and/or a single crystal of titania, making it difficult to synthesize titanoaluminosilicate in which titanium is uniformly distributed in the crystal. It's not easy to do.

On the other hand, JP-A-62-162617 discloses hydrothermal synthesis using titanium alkoxide, silicon alkoxide, and aluminum alkoxide as a titanium source, a silica source, and an aluminum source, respectively, in the presence of a nitrogen-containing organic compound (e.g., alkylammonium hydroxide). A method for producing a crystalline synthetic zeolite material (titanoaluminosilicate) is disclosed. This titanoaluminosilicate has a defined composition ratio of silicon oxide, titanium oxide, and aluminum oxide constituting it, and is characterized by an X-ray diffraction spectrum. However, these alkoxides have the disadvantage that they are easily condensed by moisture in the air and are not easy to handle. Furthermore, in the hydrothermal synthesis of crystalline substances using such monomers as raw materials, it is necessary to strictly control the synthesis conditions, that is, the crystal formation process. Due to slight variations in the synthesis conditions, crystalline titanoaluminosilicate may not be obtained reproducibly1, and raw materials not incorporated into the crystals remain as impurities.

Furthermore, in order to obtain a crystalline material by this method, the charging ratios of the titanium source, silica source, and aluminum source are significantly limited. That is, there is a problem that the titanoaluminosilicate will not crystallize unless the molar ratio of the silicon source to the aluminum source is about 300 or more.

[Problem to be solved by the invention]

As mentioned above, a method for producing titanoaluminosilicate in which titanium and aluminum are highly uniformly distributed in zeolite crystals and in which the synthesis operation is easy has not been established. Therefore, an object of the present invention is to provide a method for producing crystalline titanoaluminosilicate in which the composition of each oxide can be adjusted over a wide range and in which titanium and aluminum are highly uniformly distributed within the zeolite crystal, by a relatively simple synthetic operation. It's about doing.

[Means to solve the problem]

That is, in the present invention, the molar ratio of silica to alumina is 30.
The present invention relates to a method for producing crystalline titanoaluminosilicate, which comprises subjecting the aluminosilicate and titanium alkoxide described above to a hydrothermal synthesis reaction in the presence of alkylammonium hydroxide.

Further, the present invention will be explained in detail. One of the features of the method for producing crystalline titanoaluminosilicate according to the present invention is that aluminosilicate having a three-dimensional structure of 5104- and ^1O1-tetrahedrons is used as a raw material for the hydrothermal synthesis reaction. It is well known that crystalline aluminosilicate, titanoaluminosilicate, etc. are synthesized by hydrothermal synthesis reaction using monomer raw materials, but as shown in the present invention, aluminosilicate is used as a starting material. The method is still unknown. As will be described later, it is an interesting fact that an aluminosilicate having a certain crystal structure undergoes structural conversion to produce a different type of crystalline titanoaluminosilicate.

That is, by using a precursor of crystalline titanoaluminosilicate rather than a monomer raw material, the desired product can be obtained extremely smoothly. The method of the present invention also has the advantage that the composition of each oxide in the titanoaluminosilicate can be adjusted over a wide range.

In the present invention, the aluminosilicate used as a raw material for the hydrothermal synthesis reaction is not particularly limited in its crystallinity, such as a crystalline substance, an amorphous substance, or a partially crystalline substance. Specifically, either natural products and/or synthetic products may be used. As natural materials, clinoptilolite, hyurandite, mordenite, analcyme, wairakite, etc. are preferably used. On the other hand, as synthetic products, faujasites such as Y type, A type, and X type,
Preferred examples include mordenite, pentasil type, L type, Ω type, ophthalate, erionite, ferrierite, and clinoptilolite type.

The ratio of silicon to aluminum in these aluminosilicate is set to be 30 or more in terms of the molar ratio of silica to alumina. When the molar ratio is less than 30, even if the hydrothermal synthesis reaction described below is performed, amorphous titania is likely to be produced, and it is difficult to obtain titanoaluminosilicate crystals in which titanium is highly dispersed. Such an aluminosilicate having a molar ratio of silica to alumina of 30 or more can be used as it is, regardless of whether it is a natural product or a synthetic product, as long as it is in that state. If the molar ratio of silica to alumina is less than 30, aluminum in the aluminosilicate can be removed in advance before the aluminosilicate can be subjected to the hydrothermal synthesis reaction.

Removal of aluminum, or dealumination, can be performed by known techniques. For example, hydrochloric acid, sulfuric acid,
Acid treatment with inorganic acids such as phosphoric acid, organic acids such as acetic acid, propionic acid, and trifluoromethanesulfonic acid, silicon substitution treatment with silicon tetrachloride, ammonium fluorosilicate, etc., and EDTA.

Preferred methods include methods using phosgene and nitrosyl chloride. The molar ratio of silica to alumina in the aluminosilicate used as a raw material is preferably 8.
It is 5 or more.

As the titanium alkoxide, tetramethyl orthotitanate, tetraethyl orthotitanate, tetrapropyl orthotitanate, tetrabutyl orthotitanate, etc. are preferably used.

Furthermore, these titanium alkoxides may be either monomers or oligomers.

Examples of alkylammonium hydroxide include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, with tetrapropylammonium hydroxide being particularly preferred.

The charging ratio of these reaction raw materials when hydrothermally synthesizing titanoaluminosilicate in the present invention is preferably as follows. Titanium alkoxide has a molar ratio of 0.5 to 3001 to 5102 in alumina silicate.
More preferably, the molar ratio is 1 to 200. The molar ratio of alkylammonium hydroxide to S+02 is likewise in the range of 0.5 to 1O. The reaction is preferably carried out in a medium, and water can be used as the medium. The amount of water used is preferably in a molar ratio of 10 to 200 to Stew.

In the reaction, gamma hydroxide, lekylammonium, and water are mixed, and if necessary, this mixture is hydrolyzed in advance before the hydrothermal synthesis reaction to remove the alcohol produced and reduce the weight of the reactants. There are many things you can reduce. However, even if hydrolysis is not performed at this point, the properties of the produced titanoaluminosilicate do not change in particular. In order to proceed with hydrolysis in advance, the temperature is preferably 2 to 120°C.
It is preferable to remove the generated alcohol while stirring at a temperature of 0 to 100°C for a period of 0.1 to 20 hours.

Compound i prepared as described above is subjected to a hydrothermal synthesis reaction. In the hydrothermal synthesis reaction, the mixture is heated at a temperature of 60 to 300°C, preferably 100 to 250°C, and 1
This is carried out by stirring for ~100 hours. At this time, the pressure can be applied either under autogenous pressure or under increased pressure, but usually it is carried out under autonomic pressure. Additionally, a mineralizing agent may be added to facilitate crystallization in this reaction. Examples of mineralizing agents include sodium chloride, potassium chloride, sodium bromide, potassium bromide, and sodium sulfate.

The crystalline titanoaluminosilicate of the present invention can be produced by thoroughly washing the solid powder crystallized by hydrothermal synthesis with ion-exchanged water and heat-treating it at 300 to 700°C for 2 to 20 hours. can.

The titanoaluminosilicate according to the present invention is a crystal with extremely high thermal stability, and is
It has a pentasil-type structure similar to M-34.

Furthermore, the titanoaluminosilicate produced according to the present invention has a wide range of uses, including as an ion exchanger and an adsorbent, in addition to being used as a catalyst. In particular, the titanoaluminosilicate obtained by the method of the present invention not only has solid acid sites based on aluminum, but also has titanium highly distributed in the crystal, so it can undergo alkylation, isomerization, disproportionation, and oligomerization. It can be used not only for catalysis by solid acids such as , crab king, and hydrogenation reactions, but also for hydroxylation reactions, epoxidation reactions, oxidation reactions, etc. by oxidizing agents such as hydrogen peroxide.

Effects of the Invention] According to the method of the present invention, titanoaluminosilicate in which titanium and aluminum are highly distributed within the crystal can be produced. Furthermore, since aluminosilicate is used as a raw material for hydrothermal synthesis, the desired product can be obtained smoothly. In addition, each oxide composition of titanoaluminosilicate is
If the molar ratio of silica to alumina contained in the aluminosilicate is 30 or more, other factors can be adjusted over a wide range. In addition, aluminosilicate is thermally
Furthermore, since it is stable against moisture, it is easy to operate the reaction.

The catalytic performance of the crystalline titanoaluminosilicate obtained by the present invention is not limited to solid acid catalytic functions such as alkylation, isomerization, and disproportionation reactions, but also catalytic functions such as hydroxylation and epoxidation using peroxide as an oxidizing agent. It has excellent properties in oxidation reactions.

〔Example〕

EXAMPLES Hereinafter, the present invention will be further explained with reference to examples, but the present invention is not limited to the following examples.

Example 1 150 g of Y-type zeolite (TS Z-330HUA manufactured by Tosoh) with a molar ratio of silica to alumina of 5.9 was placed in a three-necked flask with an internal capacity of 2000-1.60.
Suspended in 1,500 mol/1 hydrochloric acid aqueous solution and heated to 95°C.
The mixture was stirred for 2 hours. The mixture was then centrifuged, thoroughly washed with ion-exchanged water, and dried at 90° C. for a day and night to obtain an aluminosilicate as a raw material (hereinafter, this aluminosilicate will be abbreviated as Y-1).

30 g of the obtained Y-1 was suspended in 100 ml of ethanol and stirred at room temperature. Then, 5.47 g of tetraethylorthotitanate was added dropwise, followed by 10 g of tetrapropylammonium hydroxide (25% solution) in water.
0g was added dropwise. This mixture was heated to about 80°C, and the ethanol and water produced by the hydrolysis were removed by distillation (1
2C1-). After adding 320 g of water to the distilled mixture, it was filled into a Hastelloy autoclave with an internal capacity of 500 cm, and the temperature was raised to 170 ° C. in 2 hours under autostatic pressure.
Stirred for 5 hours. The contents of the autoclave were centrifuged and thoroughly washed with 60°C ion-exchanged water. The obtained white powder solid was dried at 90°C for a day and night, and then heat-treated at 550°C for 5 hours to obtain 23 g of titanoaluminosilicate (hereinafter, this titanoaluminosilicate will be abbreviated as TAS-1).
I got it.

Table 1 shows the results of chemical analysis of the powder composition.
Shown below. Table 2 also shows the main peaks determined by X-ray diffraction (XRD). For reference, please refer to JP-A-62-16261.
Table 3 also shows the XRD results of the titanoaluminosilicate prepared according to the method described in No. 7 (silica/alumina ratio: 137, silica/titania ratio: 40).

Example 22i1t and 3 In Example 2, the weight of tetraethylorthotitanate was 2
Titanoaluminosilicate was prepared in the same manner as in Example 1 except that the amount was changed to 0.6 g (TAS-2) (yield: 23 g).

In Example 3, the weight of tetraethylorthotitanate was 3
．． Titanoaluminosilicate was prepared in the same manner as in Example 1 except that the amount was changed to 48 g (TAS).

-3) (yield 22g). Table 1 shows the composition of the obtained powder.

Example 4 150 g of Y-type zeolite with a molar ratio of silica to alumina of 5.9 was added to an aqueous solution of 0.80 mol/1 hydrochloric acid 15
00 ml and stirred at 95°C for 2 hours.

Then, after centrifugation and thorough washing with ion-exchanged water,
It was dried at ℃ for a day and night to obtain aluminosilicate as a raw material (Y-2). Titanoaluminosilicate was prepared in the same manner as in Example 1, except that Y-2 was used in place of Y-1 and the weight of tetraethylorthotitanate was changed to 2.69 g (TAS-4) (yield: 23 g). ). Table 1 shows the composition of the obtained powder.

Examples 5 and 6 In Example 5, the weight of tetraethylorthotitanate was 2
Titanoaluminosilicate was prepared in the same manner as in Example 4, except that the amount was changed to 0.3 g (TAS-5) (yield: 23 g).

In Example 6, the weight of tetraethylorthotitanate was 9
．． Titanoaluminosilicate was prepared in the same manner as in Example 4, except that the amount was changed to 58 g (TAS-6) (yield: 23 g).

Example 7 Mordenite type zeolite with a molar ratio of silica to alumina of 21.8 (TSZ 640 XOA manufactured by Tosoh)
) 50g 6. Suspended in Omol/1 hydrochloric acid, 95
Stirred at ℃ for 2 hours. Next, it was centrifuged, thoroughly washed with ion-exchanged water, and then dried at 90°C for a day and night to obtain aluminosilicate as a raw material (Y-3). Titanoaluminosilicate was prepared in the same manner as in Example 2 except that Y-3 was used instead of Y-1 (TAS-7)
(Yield 22g). Table 1 shows the composition of the obtained powder.

Comparative Example 1 30 g of Y-type zeolite (TSI 3308118 manufactured by Tosoh) having a molar ratio of silica to alumina of 5.9 was suspended in ethanol 6 (lit!) and stirred at room temperature. Then, 0. 93 g was added dropwise, followed by 126 g of an aqueous tetrapropylammonium hydroxide solution (25% solution). This mixture is about 8
The mixture was heated to 0° C., and ethanol and water produced by hydrolysis were distilled off. Water 185 to the distilled mixture
After adding g, the internal volume is 500ml! The mixture was charged into a Hastiloid autoclave, heated to 170° C. over 2 hours under autostatic pressure, and stirred for 50 hours. The contents of the autoclave were centrifuged and thoroughly precleaned with 60°C deionized water.

After drying the obtained white powder solid at 90°C for a day and night,
It was heat treated at ℃ for 5 hours. However, the white powder solid was a mixture of Y-type zeolite and titania.

Comparative Example 2 Hydrothermal synthesis was carried out according to the method described in JP-A-62-162617. aluminum isopropoxide 0.3
01g of tetrapropylammonium hydroxide aqueous solution (2
5% solution) was dissolved in 87.8 g. In another container,
4.53 g of tetraethylorthotitanate was dissolved in 92.2 g of tetraethylorthosilicate, and the mixed solution was slowly added dropwise to the solution prepared previously while stirring. After stirring the incense mixed solution at 60° C. for 4 hours, 310 ml of pure water was added. The resulting mixture was filled into a Hastelloy autoclave, heated to 170° C. for 2 hours under autogenous pressure, and stirred for 5 hours. However, the reaction mixture did not crystallize.

Example 8 TAS-11, 0g in a four-bottle flask with an internal capacity of 500-
, 20 g of phenol and 100 g of water were mixed, 95
Stirred at ℃ for 1 hour. Thereafter, the temperature was adjusted to 80° C., and 60 g of a hydrogen peroxide aqueous solution (3.75% by weight) was added dropwise over 1 hour, followed by stirring at the same temperature for 14 hours. Analysis of the reaction product by liquid chromatography revealed that dihydroxybenzene (hydroquinone and catechol) was obtained in a yield of 77.8% based on hydrogen peroxide.

Table 2 Table 3

Claims (1)

[Claims] A method for producing crystalline titanoaluminosilicate, which comprises subjecting an aluminosilicate having a molar ratio of silica to alumina of 30 or more and titanium alkoxide to a hydrothermal synthesis reaction in the presence of alkylammonium hydroxide.