JP3303341B2 - Method for producing beta zeolite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a beta zeolite useful as a catalyst for reactions such as isomerization, transalkylation, disproportionation, hydration, esterification, and decomposition of adsorbents and organic compounds. It is.

[0002]

BACKGROUND OF THE INVENTION Beta zeolites are known. This is produced by a hydrothermal synthesis in which a mixture containing a template agent such as a silica source, an alumina source, an alkali source, a tetraethylammonium cation and water is placed in a closed vessel, and heated to react under self-generated pressure. Regarding this synthesis method, see U.S. Pat. S. P. 3,308,069. Recently, P.I. A. Jacobs et al., A
ppl. Catal. , 31 ,, P35 (1987),
A synthesis method is also described in EP187, 522 and the like. Further, the crystal structure of this is described in J. Am. B. Higg
ins et al. Zeolites, 8 , P446 (198
8) and Chem. & Eng. News, 1988,
6/20, p. 23.

[0003]

One of the problems in producing the beta zeolite is that the slurry containing beta zeolite produced by hydrothermal synthesis has extremely poor filterability. This is presumed to be due to the fact that the beta zeolite has a very small particle size of 0.1 μm or less, and the presence of a polysilicate component in the slurry. In general, zeolite is a charged particle, and thus a slurry containing the zeolite can be aggregated by adding a polymer flocculant. However, the slurry containing beta-type zeolite produced by hydrothermal synthesis is strongly alkaline, and does not aggregate even when a general anionic or cationic polymer flocculant is added.

[0004]

According to the present invention, an acid is added to a slurry containing beta-type zeolite produced by hydrothermal synthesis to adjust the pH of the slurry to 4-8.5, followed by filtration according to a conventional method. By doing so, zeolite can be easily separated and recovered from the slurry. On this occasion,
When further adding an anionic polymer flocculant to the slurry,
Filtration becomes easier. The present invention will be described in more detail. In the present invention, the beta zeolite synthesis reaction itself can be carried out according to a conventional method. Examples of the silica source include silica sol, silica gel, irisole, precipitated silica, ethyl silicate, and other silicate esters.
As the alumina source, aluminates such as sodium aluminate and potassium aluminate are preferable, but aluminum nitrate, aluminum sulfate, aluminum acetate and other aluminum mineral and organic acid salts, and also hydrated alumina and the like may be used. Can be. Alkali hydroxide, particularly sodium hydroxide, is generally used as the alkali source. Tetraethylammonium (TE
The salt or hydroxide of A) is generally used, but a tetraethylphosphonium cation can also be used. These raw materials are generally blended so as to have the following molar composition.

[0005] SiO ₂ / Al ₂ O ₃ = 10 to 200 Na ₂ O / (TEA) ₂ O = 0.0 to 0.2 (TEA) ₂ O / SiO ₂ = 0.05 to 0.5 H ₂ O / (TEA) ₂ O = 40-150

[0006] These raw materials are mixed well, charged into a reaction vessel, and sealed, and the temperature is 60 to 200 ° C, preferably 100 to 1 ° C.
The reaction is carried out under self-generated pressure by heating to 80 ° C. The time required for the reaction is generally from several hours to several hundred hours, and the longer the reaction, the lower the temperature. Therefore usually 110
Most preferably, the reaction is carried out at -180 ° C. Upon completion of the zeolite synthesis reaction, the reactor is cooled and then the pH is adjusted to 4-8.5 by adding acid to the slurry. To facilitate handling, it is preferable to dilute the slurry by adding water before adding the acid. As the acid, sulfuric acid or hydrochloric acid is preferred, but if desired, other inorganic acids such as nitric acid or carbonic acid, and furthermore, organic acids can be used. This neutralization produces a gel-like substance, which is considered to be derived from the polysilicate component existing in the slurry.
It is presumed that this exhibits a binder-like action of fine beta zeolite, and contributes to improvement in filterability and further in handling. In the present invention, prior to filtering the neutralized slurry as described above, adding an anionic polymer flocculant such as a partial hydrolyzate of polyacrylamide to the slurry further improves the filterability.

[0007] By the above-described neutralization and further addition of a flocculant, the filterability of the slurry is remarkably improved.
Filtration can be easily carried out using various conventional filter machines, and further, washing with water after filtration is easy.

[0008]

According to the present invention, beta zeolite can be easily separated and recovered from a slurry containing beta zeolite produced by hydrothermal synthesis.

[0009]

【Example】

(Example 1) aqueous solution of sodium aluminate (Sumitomo Chemical's products .NA-170, Al ₂ O ₃ content of 18.15%)
18.72 g, 129.60 g of a 40% aqueous solution of tetraethylammonium hydroxide and 90.6 water
8 g were mixed to form a uniform solution. 208.3 g of tetraethylorthosilicate was added to the mixture, and the mixture was stirred and gradually heated to cloudy. After 2 hours, this was heated to 60-70 ° C. on a rotary evaporator to distill most of the ethanol. After diluting the total amount to 380 g with water, the mixture was placed in an autoclave and heated to 100 ° C.
Allowed to react for hours.

The contents of the autoclave were milky white slurries and did not show sedimentation when allowed to stand. When a part of the slurry was air-dried at room temperature and subjected to X-ray diffraction, the X-ray chart completely coincided with that of the beta zeolite. Since the slurry could hardly be filtered by a conventional filtration method using filter paper, the slurry was diluted 20 times with water and then neutralized to pH 7.5 with 1 N sulfuric acid to produce a gel substance. Next, 0.1 part of an anionic polymer flocculant [Diaclear (registered trademark) MA-3000H], which is a partial hydrolyzate of polyacrylamide, was added thereto.
% Aqueous solution was added as a coagulant so as to be 3 ppm. The slurry separated into a clear and colorless supernatant and a precipitate. The mixture was filtered by a conventional method, and the cake was washed with water and dried. When X-ray diffraction was performed, the X-ray chart was completely consistent with that of the beta zeolite.

(Example 2) 9.36 g of an aqueous solution of sodium aluminate, 0.95 g of sodium hydroxide and 2.38 g of potassium hydroxide were dissolved in 736.3 g of a 10% aqueous solution of tetraethylammonium hydroxide. 63.0 g of powdered silica gel was added thereto, and the mixture was charged into an autoclave including a Teflon inner cylinder. The mixture was heated to 135 ° C. and reacted for 24 hours. The appearance of the resulting slurry was similar to that of Example 1, and the filterability was extremely poor. When a part of this product was sampled and subjected to X-ray diffraction, the X-ray chart coincided with that of beta zeolite.

This slurry was diluted with water in the same manner as in Example 1, neutralized to pH 7.5 with sulfuric acid, and further added with an anionic polymer flocculant. The slurry was separated into a supernatant and a precipitate, and could be easily filtered by a conventional method.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C01B 39/00-39/54 B01J 29/00 B01J 20/16 CA (STN) JICST file (JOIS) WPI / L

Claims (3)

(57) [Claims] Claims 1. A mixture containing a silica source, an alumina source, an alkali source, a template agent and water is heated in a closed vessel to form a slurry containing beta zeolite.
Then, an acid is added to the slurry to adjust the pH of the slurry to 4-8.5, followed by filtration. 2. An acid and an anionic polymer coagulant are added to a slurry containing beta-type zeolite to adjust the pH of the slurry to 4.
2. The method according to claim 1, wherein the filtration is carried out after adjusting to -8.5. 3. The method according to claim 2, wherein the anionic polymer flocculant is a partial hydrolyzate of polyacrylamide.