JP7052346B2 - Method for producing crystalline zeolite - Google Patents

Description

The present invention relates to a method for industrially advantageous production of crystalline zeolite. Specifically, it is a method for producing a crystalline zeolite in which a zeolite slurry is filtered and dehydrated in the presence of a quaternary ammonium salt.

Industrially, crystalline zeolites are used as solid catalysts in the isomerization and disproportionation processes of aromatic compounds. In the production of crystalline zeolite, if the primary particle size becomes too large, the outer surface surface thereof decreases, so that the catalytic activity decreases, while if the particle size becomes too small, the handleability such as filterability is good. It is known that the particle size disappears, and in order to achieve both catalytic activity and filterability, a method of adjusting the particle size by the molar ratio of hydroxide ions to silicon in the raw material has been proposed. (See Patent Document 1)

Japanese Unexamined Patent Publication No. 2013-11257 Japanese Unexamined Patent Publication No. 2008-238136 Japanese Unexamined Patent Publication No. 2002-255541

However, the method of adjusting the particle size is not always satisfactory from the viewpoint of catalytic activity. Therefore, an object of the present invention is to improve the filterability of the crystalline zeolite slurry and to provide a method for producing a highly active zeolite.

The present invention provides a method for producing the following crystalline zeolite in order to achieve the above object. A mixture containing a silica source, an alumina source, a hydroxyl ion source, and water is hydrothermally synthesized to obtain a zeolite slurry, and then the quaternary ammonium salt represented by the formula 1 is 100% by weight to 500% by weight based on the zeolite slurry. A method for producing a crystalline zeolite , which comprises a step of filtering and dehydrating the zeolite slurry.
R ₂ N ⁺ (CH ₃ ) ₂ X ・ ・ ・ Equation 1
Here, R represents an alkyl group having 10 to 20 carbon atoms, and X represents a halogen.

In the method for producing a crystalline zeolite of the present invention, the filterability of the zeolite slurry can be improved by filtering and dehydrating the zeolite slurry in the presence of the quaternary ammonium salt represented by the formula 1.

Hereinafter, the present invention will be described in detail. The crystalline zeolite to be produced by the present invention contains silicon and oxygen as elements constituting its skeleton, and among them, those having a pentasil-type or mordenite-type structure are preferable, and a pentasil-type or mordenite-type structure is preferable. Among the zeolites having the above, those having a Si / Al ratio of 15 to 50 are particularly preferable. Pentacyl-type or mordenite-type zeolites can hydrothermally synthesize a mixed solution under self-pressure. Various methods have been disclosed so far as methods for producing pentasyl-type zeolite and mordenite-type zeolite. For example, Japanese Patent Application Laid-Open No. 2008-238136 and Japanese Patent Application Laid-Open No. 2002-255541 can be mentioned.

In the present invention, a mixture containing a silica source, an alumina source, a hydroxyl ion source, and water is subjected to a hydrothermal synthesis reaction. If necessary, a structure-defining agent may be used. Examples of the silica source include amorphous silica such as colloidal silica, silica gel and fumed silica, alkali silicate such as sodium silicate and potassium silicate, and examples of the alumina source include sodium aluminate.

Further, the skeletal structure of the zeolite to be synthesized can be controlled by adding an additive such as a structure-defining agent to the reaction raw material as needed. For example, tartaric acid may be added when producing a pentacil-type zeolite, or a quaternary ammonium salt such as tetraethylammonium hydroxide may be added when producing a mordenite-type zeolite.

The temperature in hydrothermal synthesis is preferably 80 to 200 ° C., and the hydrothermal synthesis time is preferably 1 to 200 hours. The pressure in hydrothermal synthesis is an absolute pressure, preferably in the range of 0.10 to 2.0 MPa. The method of hydrothermal synthesis is not particularly limited, but is carried out, for example, by enclosing the mixture in a reaction vessel such as an autoclave and stirring the mixture in a closed state under the above temperature conditions.

In the present invention, the quaternary ammonium salt represented by the formula 1 is added to the reaction mixture (zeolite slurry) containing the crystals obtained by hydrothermal synthesis, and the mixture is stirred. In the quaternary ammonium salt represented by the formula 1, R is an alkyl group having 10 to 20 carbon atoms, and X is a halogen. The quaternary ammonium salt may be a mixture in which the alkyl group represented by R has an alkyl group having a different carbon number, but an alkyl group having 14 to 16 carbon atoms is preferable. The halogen represented by X is preferably chlorine. When the quaternary ammonium salt represented by the formula 1 is added in an amount of 100 wt ppm or more based on the reaction mixture (zeolite slurry), the effect of agglomerating the zeolite crystals and shortening the filtration time can be obtained, while the addition of 500 wt ppm or more gives the effect. Since bubbles are generated and it becomes difficult to handle, the addition amount is preferably 100% by weight or more and 500% by weight or less, and more preferably 200% by weight or more and 500% by weight or less. Further, as the quaternary ammonium salt represented by the formula 1, a commercially available product such as Lipocard (Lion Specialty Chemicals Co., Ltd.) may be used.
R ₂ N ⁺ (CH ₃ ) ₂ X ... Equation 1

The temperature of the reaction mixture is preferably 20 ° C to 80 ° C. After stirring, the reaction mixture is filtered and separated into a concentrate containing crystals and a filtrate. By adding the quaternary ammonium salt represented by the formula 1, the time required for filtration separation can be shortened. As a filtration method, a membrane separation method is preferable. The material and pore diameter of the film are appropriately set. The filtration may be pressure filtration, suction filtration or centrifugal filtration. The pressure in the filtration is appropriately set, and either constant flow filtration in which the filtration amount is kept constant or constant pressure filtration in which the membrane differential pressure is kept constant may be used. The temperature in the filtration is preferably in the range of room temperature to the temperature during the hydrothermal synthesis reaction. The pressure in the filtration is an absolute pressure, preferably in the range of 0.01 to 1 MPa.

The concentrate containing the crystals obtained in the filtration step is washed with water until the pH of the washing liquid obtained by washing reaches 8.5 to 11.2 at 25 ° C. In order to wash with water until the pH of the washing liquid obtained by the washing at 25 ° C. becomes 8.5 to 11.2, the pH can be adjusted to the above range by, for example, adjusting the amount of washing water. ..
The washed crystals obtained in the washing step may be recovered as a slurry, but it is preferably recovered as a dried product by drying. As a drying method, it is preferable to use a shelf-stage dryer, and the drying temperature is preferably 50 ° C. or higher and 300 ° C. or lower. The water content of the dried crystals is preferably 10% or less, and the water content may be measured with an infrared moisture meter. The water content of the crystals after drying can be adjusted by the drying time and the like.

Next, the present invention will be described in more detail by way of examples.

(Example 1)
27.5 grams of a caustic soda aqueous solution (NaOH content 25% by weight, _H2O content 75% by weight) and 9.6 grams of tartrate acid powder were dissolved in 521.4 grams of ion-exchanged water. 33 grams of a sodium aluminate solution (Al ₂ O ₃ content 19% by weight, Na ₂ O content 20% by weight, H ₂ O content 61% by weight) was added to this solution to prepare a uniform solution. Hydrous silicic acid (SiO ₂ content 89.0% by weight, Al ₂ O ₃ content 0.3% by weight, Na ₂ O content 0.2% by weight, H ₂ O content 10.5% by weight, nip seal VN) in this mixture. -3, Tosoh) 108 grams was gradually added with stirring to prepare a uniform slurry-like aqueous reaction mixture. The reaction mixture was placed in a 10 L autoclave, sealed, and then reacted at 160 ° C. for 72 hours with stirring at 120 rpm.

The slurry containing the crystals obtained above is heated to 70 ° C., 200% by weight ppm of dialkyl chloride (C14 to C18) dimethylammonium (trade name: Lipocard, Lion Specialty Chemicals Co., Ltd.) is added, and the mixture is 120 rpm for 1 hour. After stirring, suction filtration was performed for 10 minutes using a 5C filter paper with a 50 mmφ nutche. When the water content of the obtained cake was measured with an infrared moisture meter, it was 67%.
The obtained cake was washed with distilled water 5 times, filtered repeatedly, dried at about 60 ° C. for 12 hours, and measured with a Cu tube and an X-ray diffractometer using Kα-rays. As a result, the obtained zeolite was a pentasil-type zeolite. It turned out to be.

(Example 2)
27.5 grams of a caustic soda aqueous solution (NaOH content 25% by weight, _H2O content 75% by weight) and 9.6 grams of tartrate acid powder were dissolved in 521.4 grams of ion-exchanged water. 33 grams of a sodium aluminate solution (Al ₂ O ₃ content 19% by weight, Na ₂ O content 20% by weight, H ₂ O content 61% by weight) was added to this solution to prepare a uniform solution. Hydrous silicic acid (SiO ₂ content 89.0% by weight, Al ₂ O ₃ content 0.3% by weight, Na ₂ O content 0.2% by weight, H ₂ O content 10.5% by weight, nip seal VN) in this mixture. -3, Tosoh) 108 grams was gradually added with stirring to prepare a uniform slurry-like aqueous reaction mixture. The reaction mixture was placed in a 10 L autoclave, sealed, and then reacted at 160 ° C. for 72 hours with stirring at 120 rpm.

The slurry containing the zeolite crystals obtained above is heated to 70 ° C., 500% by weight ppm of dialkyl chloride (C14 to C18) dimethylammonium (trade name: Lipocard, Lion Specialty Chemicals Co., Ltd.) is added, and 1 at 120 rpm. After stirring for a time, suction filtration was performed for 10 minutes using a 5C filter paper with a 50 mmφ nutche. When the water content of the obtained cake was measured with an infrared moisture meter, it was 61%.

The obtained cake was washed with distilled water 5 times, filtered repeatedly, dried at about 60 ° C. for 12 hours, and measured with a Cu tube and an X-ray diffractometer using Kα-rays. As a result, the obtained zeolite was a pentasil-type zeolite. It turned out to be.

(Comparative Example 1)
27.5 grams of a caustic soda aqueous solution (NaOH content 25% by weight, _H2O content 75% by weight) and 9.6 grams of tartrate acid powder were dissolved in 521.4 grams of ion-exchanged water. 33 grams of a sodium aluminate solution (Al ₂ O ₃ content 19% by weight, Na ₂ O content 20% by weight, H ₂ O content 61% by weight) was added to this solution to prepare a uniform solution. Hydrous silicic acid (SiO ₂ content 89.0% by weight, Al ₂ O ₃ content 0.3% by weight, Na ₂ O content 0.2% by weight, H ₂ O content 10.5% by weight, nip seal VN) in this mixture. -3, Tosoh) 108 grams was gradually added with stirring to prepare a uniform slurry-like aqueous reaction mixture. The reaction mixture was placed in a 10 L autoclave, sealed, and then reacted at 160 ° C. for 72 hours with stirring at 120 rpm.

The slurry containing the zeolite crystals obtained above was heated to 70 ° C., stirred at 120 rpm for 1 hour, and then suction filtered with a 50 mmφ nutche using a 5C filter paper for 10 minutes. The obtained cake had a high water content and liquefied over time, making it impossible to measure the water content with an infrared moisture meter.

The obtained cake was washed with distilled water 5 times, filtered repeatedly, dried at about 60 ° C. for 12 hours, and measured with a Cu tube and an X-ray diffractometer using Kα-rays. As a result, the obtained zeolite was a pentasil-type zeolite. It turned out to be.

The filterability of the crystalline zeolite slurry can be improved, and a highly active zeolite can be efficiently produced.

Claims (4)

A mixture containing a silica source, an alumina source, a hydroxyl ion source, and water is hydrothermally synthesized to obtain a zeolite slurry, and then the quaternary ammonium salt represented by the following formula is 100% by weight to 500% by weight based on the zeolite slurry. A method for producing a crystalline zeolite , which comprises a step of filtering and dehydrating the zeolite slurry.
R ₂ N ⁺ (CH ₃ ) ₂ X
Here, R represents an alkyl group having 10 to 20 carbon atoms, and X represents a halogen. The method for producing a crystalline zeolite according to claim 1 , wherein the Si / Al ratio in the mixture is 15 to 50. The method for producing a crystalline zeolite according to claim 1 or 2 , wherein the obtained crystalline zeolite is an MFI type zeolite. The method for producing a crystalline zeolite according to claim 1 or 2 , wherein the obtained crystalline zeolite is a mordenite type zeolite using tetraethylammonium hydroxide as a template.