JPH0526723B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ultrastable faujasite type zeolite and a method for producing the same.

Zeolite is a three-dimensionally condensed aluminosilicate that is naturally produced in large quantities, and can also be synthesized to produce types that are not naturally produced.

Currently, there are said to be more than 150 types of zeolite. Zeolites have large cavities or pores within their crystal structure, and usually store water molecules inside, but they can be easily heated or evacuated under reduced pressure without causing collapse of the crystal structure. Water molecules can be removed. The zeolite can then occlude other organic and inorganic molecules of a size that can fit into the cavities. In addition, zeolite cations can be easily ion-exchanged with other cations. Furthermore, zeolite also has properties as a solid acid.

Because of these characteristics, zeolites are useful substances as desiccants, adsorption/separation agents, detergent builder components, or catalyst components, and are currently widely used industrially. Zeolites are used for a wide range of purposes, particularly with regard to their use as catalysts, and are known to be extremely useful in petroleum refining operations, among others.

Among the various zeolites, zeolites with large cavities, classified as faugiasite-type zeolites (hereinafter referred to as faugiasite), are suitable for processes such as fluid catalytic cracking, hydrocracking, isomerization, and alkylation. has been widely used. However, although these zeolites have satisfactory activity in the reaction of the above process, they are known to lack crystal structure stability at high temperatures.

Until now, zeolite Y (generally 3 or more SiO ₂ /
Synthetic phasiasite with Al ₂ O ₃ molar ratio is called zeolite Y) has good activity but relatively low structural stability at high temperatures, so attempts to improve its stability have been made. has been done.
As a result, several thermally stable forms of zeolite Y have been produced. Their manufacturing methods are summarized below.

“Ultra-stable zeolite” as used herein means
Highly resistant to crystallinity reduction due to high temperatures and steaming treatments, with an _M2O content of less than 4wt%, preferably less than 1wt% (M
is Na, K, or other alkali metal ion)
, the lattice constant is 24.55A or less, and the crystal
It means zeolite Y having a SiO ₂ /Al ₂ O ₃ molar ratio in the range of 3.5 to 7 or higher.

Such ultra-stable zeolites are produced by removing the alkali metal ions from the zeolite by exchanging them for ions, typically ammonium ions, that decompose on calcination, leaving behind protons, and then Obtained by reducing the lattice constant by calcination treatment at a temperature of ~800°C. That is, ultrastable zeolites are identified both by a smaller lattice constant and a lower alkali metal content in the crystal structure.

Shrinkage of the crystal lattice occurs when aluminum in the zeolite skeleton undergoes hydrolysis and detaches during firing, and then silicon moves from partially collapsed crystals or impurities such as silicate to defective points in the lattice, or It is thought that this occurs due to rearrangement of the Si--O--Si bonds to form new Si--O--Si bonds.

[Prior Art] Japanese Patent Publication No. 42-8129 and Japanese Patent Publication No. 42-20386 disclose a method for producing zeolite called "Z-14US".
They prepare faujasite with a SiO ₂ /Al ₂ O ₃ molar ratio of 3.5 to 7 using a salt of a nitrogen base, typically ammonium sulfate, in an aqueous solution of its alkali metal,
Usually, after ion exchange treatment until the sodium content is 5wt% or less, zeolite is
This method involves firing at a temperature of 1040°C.

And the alkali metal content of zeolite is 1wt
% and a lattice constant of 24.20 to 24.45 A, the ion exchange and calcination treatments are repeated until the lattice constant is 24.20 to 24.45 A, and calcination is performed at least once at a temperature of 700° C. or higher.

Furthermore, Japanese Patent Publication No. 44-31948 discloses a method of firing phosiasite, preferably 75% ammonium ion-exchanged, in an atmosphere containing 5% or more moisture, preferably at a temperature of 573 to 648°C. ing.

Furthermore, Japanese Patent Publication No. 46-9132 discloses a method of calcining ammonium type zeolite Y in the presence of a rapid stream of steam, and Japanese Patent Publication No. 47-8044 describes a method of calcining ammonium type zeolite Y in the presence of a 450 to 850 °C, under conditions where the moisture contained in the zeolite is retained within the calcination system.
A so-called self-steaming firing method is disclosed.

Japanese Patent Publication No. 47-23799 discloses that zeolite Y is ion-exchanged with an ammonium salt aqueous solution to have an alkali metal content of 1.5 to 4 wt% as an oxide, and then treated with a rare earth salt aqueous solution to reduce the rare earth metal content.
A method is disclosed in which the content is reduced to 0.3 to 10 wt%, then calcined at 371 to 871°C, and then treated with an aqueous solution of ammonium salt and/or aluminum salt.

Furthermore, JP-A-54-122700 discloses that zeolite Y with a metal cation content of 3.3 equivalent% or less is
A method of firing in an environment containing water vapor at about 0.2 to 10 atmospheres at 725 to 870°C is disclosed.

Japanese Patent Publication No. 57-15925 states that Na ₂ O is approximately
An ammonium-sodium type phosphatase containing 0.6 to 5 wt% sodium is calcined at 316 to 899°C in the presence of at least about 0.014 Kg/cm ² of water vapor and then subjected to ion exchange treatment using an aqueous ammonium salt solution. A method for reducing the sodium content to less than 1 wt% as Na ₂ O is disclosed.

JP-A-58-167420 discloses that after treating faujasite with a strongly acidic cation exchange resin, it is brought into contact with aqueous ammonia, and then heated at 500 to 800°C.
The calcination process reduces the alkali metal and alkaline earth metal content of zeolite to 2wt% as oxides.
A method is disclosed in which the process is repeated until:

[Problems to be Solved by the Invention] Generally, synthetic zeolite is obtained in the form of a fine powder of several microns or less, and zeolite Y can also only be synthesized in the form of a fine powder using conventional synthesis methods.

Therefore, when using it as a catalyst, in addition to treatments such as ion exchange and metal loading to impart the desired catalytic activity, it is necessary to form zeolite Y into spheres or pellets. During its molding, binders such as silica, alumina, silica-alumina, silica-magnesia, silica-titania, viscosity, etc. are used, and as a result, the catalyst composition usually contains 10 to 90 wt of components other than zeolite. It ends up including %. This situation is the same for the heat-stable zeolite Y described above. This is because they are stabilized against heat by the method described above starting from finely powdered synthetic zeolite Y (usually NaY, where the cation is sodium).

That is, the conventional heat-stable foliage site catalyst composition is a molded body containing a binder,
Its production required a process of mixing zeolite and a binder and molding it.

The present invention does not require such a molding step during production, and produces an aggregate consisting only of zeolite that is substantially stable to heat, and therefore can be used as a catalyst as it is without molding. The present invention provides a method for producing the same.

[Means for Solving the Problems] A method for manufacturing faujasite of the present invention will be described below.

One of the key points is that NaY, which is the starting material for stabilizing zeolite against heat, was synthesized as a dense aggregate of 10μ or more, which was unprecedented. And another point is the NaY obtained there.
We have discovered a method for stabilizing aggregates against heat while suppressing the decrease in crystallinity and preventing the aggregates from being crushed. That is, the present invention was arrived at due to these two matters.

First, a method for obtaining NaY aggregates will be described.

For example, by simultaneously and continuously reacting an aqueous alkali silicate solution used as a silica source with an aqueous aluminum-containing solution, a granular amorphous aluminosilicate homogeneous phase compound (hereinafter simply referred to as a homogeneous compound) is produced. , and then crystallizing the homogeneous compound in a fresh aqueous alkali hydroxide solution to produce faujasite crystals.

One of the most preferred embodiments for preparing a homogeneous compound using this method is a method in which both of the aqueous solutions are simultaneously and continuously fed into an overflow type exchange tank equipped with a stirrer and reacted under stirring. The granular homogeneous compound produced is approximately spherical, and can be obtained in any size from 10μ to 500μ by changing the residence time in the reaction tank.

It has also been found that the homogeneous compound can be crystallized while retaining its original form. That is,
Faujasite aggregates of any size from 10μ to 500μ can be produced.

Next, a method for stabilizing the aggregate against heat will be described. Even if the conventional method for stabilizing fine powder NaY is directly applied to the aggregates, the zeolite of the present invention cannot be obtained because the aggregates are crushed or crystals are destroyed during the stabilization treatment.

A preferred method for obtaining the zeolite of the present invention is to first perform an ion exchange treatment on NaY aggregates in the form of an aqueous slurry using an aqueous ammonium salt solution, so that the sodium contained in the zeolite is preferably 5 wt% or less as Na ₂ O. After removing up to ~4wt%, baking at a temperature of 600~800℃ for 1~3 hours.
Hereinafter, this firing will be referred to as the first firing process.

Next, the first calcined zeolite is
Ion exchange treatment is performed using a strongly acidic ion exchange resin until the Na ₂ O content becomes 1 wt% or less, preferably 0.5 wt% or less.

Although this ion exchange can be performed using an aqueous ammonium salt solution, fragmentation of aggregates can be suppressed by performing it using a strongly acidic ion exchange resin. Finally, the ion-exchanged zeolite is
The zeolite of the present invention is obtained by firing at a temperature of 300 to 700°C (hereinafter referred to as second firing treatment).

Now, in the method disclosed in Japanese Patent Publication No. 42-8129, firing is typically performed twice, and in the second firing treatment, the crystal lattice is shrunk and stabilized by treatment at high temperature. In the method for producing zeolite, the first firing process of the two firings is performed at a relatively high temperature to reduce the crystal lattice to 24.60A or less.
It has been found that it is necessary to shrink the zeolite aggregate preferably to 24.55A or less in order to prevent the zeolite aggregate from becoming fine and reducing the crystallinity after the second calcination treatment. Also. Various methods are known for the firing conditions, as described in the [Prior Art] section. Floor firing is known as the simplest method.

When the zeolite is a fine powder, the depth of the zeolite layer may be about 5 to 10 cm, but when producing the aggregate of the present invention, the crystallinity of the zeolite is undesirable under such conditions. It is preferable that the depth of the zeolite layer is 10 to 20 cm due to the fact that the crystal lattice does not shrink to a large extent.

[Effects of the Invention] As is clear from the above explanation, the zeolite of the present invention is produced by synthesizing phasiasite aggregates having a particle size of 10μ or more and containing no binder, and then subjecting the obtained zeolite to ion exchange. It is produced by reducing the alkali metal content and firing it at least once at a high temperature to shrink the crystal lattice and stabilize it against heat. A thermally stabilized phougere consisting only of zeolite containing no It is a site.

The present invention will be explained in detail in the following examples.

Example 1 An aqueous solution of aluminum sulfate (Al ₂ O ₃
= 9.77w/v%, H ₂ SO ₄ = 32.94w/v%) and sodium silicate aqueous solution (SiO ₂ = 21.00w/v%,
Na ₂ O = 6.76 w/v%, Al ₂ O ₃ = 0.107 w/v%) were simultaneously and continuously supplied at fixed ratios of 1/h and 4 L/h, respectively, and the reaction was carried out under stirring. I let it happen. There is always 1 liter of reaction liquid (slurry) in the reaction tank.
An overflow port was installed so that the water would overflow beyond that point, and the residence time was set at 30 minutes. The pH of the slurry was 6.7, and the reaction temperature was 32°C.

The slurry product that overflowed from the reaction tank is separated into solid and liquid using a centrifuge, and is then collected in the washing filtrate.
A homogeneous compound having the following composition was obtained by washing with water until SO ₄ ^2- ions were no longer detected.

Na ₂ O = 6.17wt% (dry base) Al ₂ O ₃ = 10.16wt% (dry base) SiO ₂ = 83.67wt% (dry base) H ₂ O = 55wt% (wet base) Next, a regular paddle type stirrer An external heating reactor equipped with a reflux condenser at the top was charged with 2474 g of an aqueous sodium hydroxide solution with a concentration of 32.4 wt%, and then an amount of 14 wt% of the total amount of homogeneous compounds used in the reaction was charged.
After adding 833g of homogeneous compound and stirring and aging at 30℃ for 3 hours, 2873g of pure water and 5117g of homogeneous compound corresponding to 86% of the total amount of homogeneous compound were added and stirred to make a low viscosity slurry, and then aged at 30℃. The temperature was maintained for 1 hour. This slurry was then heated to 95° C. and kept under stirring for 20 hours to crystallize. The product was separated from the mother liquor by filtration, washed with water, and then dried at 110°C. As a result of X-ray diffraction, the product is SiO ₂ /Al ₂ O ₃
Extremely high purity and high crystallinity with a molar ratio of 5.5.
It was a NaY aggregate.

Additionally, this aggregate is manufactured by COULTER ELECTRONICS Co., Ltd.
COULTER COUNTER MODEL TA (COULTER COUNTER MODEL) manufactured by INC.
As a result of measuring the particle size using TA), 95% of the particle size
had a particle size of 10μ or more.

Next, the NaY aggregate was subjected to ion exchange treatment twice at 80°C using a 25 wt% ammonium chloride aqueous solution until the Na ₂ O content of the zeolite became 3.5 wt%, and after thorough washing, the obtained The zeolite was dried. Subsequently, this zeolite was subjected to a first firing treatment at a temperature of 800° C. for 1 hour in an electric Matsufuru deep bed with a zeolite layer of 15 cm. Further, 1700 g of pure water was added to 300 g of this first calcined zeolite to obtain an aqueous slurry. To this slurry, 580 ml of ion exchange resin Amberlite 200c (Porous H-type acidic cation exchange resin manufactured by Rohm and Haas) with an ion exchange capacity of 1.75 meq/ml was added and heated at 60°C.
After stirring for 2 hours, separate the resin from the aqueous slurry using a sieve, add 580 ml of fresh H-type resin to the aqueous slurry, and keep stirring at 60℃ for 2 hours. Then, ion exchange treatment was performed. Then, the resin and water were separated from the zeolite, dried, and subjected to a second firing treatment at 600° C. for 1 hour in an electric Matsufuru to obtain the phasiasite of the present invention.

From the results of chemical analysis, the Na ₂ O content is 0.22wt% and the SiO ₂ /Al ₂ O ₃ molar ratio is 5.9, and from the results of X-ray diffraction, it has a high degree of crystallinity. The lattice constant was 24.40A. Furthermore, 90wt% of this forge site is 10μ
It was a phagiasite aggregate having a particle size of the above. When this faujasite was heated at 900°C for 2 hours, the surface area decreased by only 3%.

Example 2 A first calcined zeolite was obtained by performing the same operations as in Example 1 up to the first calcining treatment. Next, add 200g of this zeolite and 500g of ammonium chloride.
Prepare a slurry consisting of 60 g of pure water and
After being maintained at 80°C for 4 hours, the slurry was filtered to obtain a zeolite wet cake. This cake was made into a slurry again with 500 g of ammonium chloride and 1300 g of pure water and kept at 80° C. for 4 hours with stirring. The zeolite was separated by filtration, thoroughly washed with pure water, and dried. The obtained zeolite is heated in electric matzuru.
The phosiasite of the present invention was obtained by firing at 700°C for 2 hours.

From the results of chemical analysis, this faujasite has a Na20 content of 0.3wt% and an SO ₂ /Al ₂ O ₃ molar ratio.
6.2, and the results of X-ray diffraction showed that it had a high degree of crystallinity and its lattice constant was 24.44A.
Furthermore, 83% of this phosiasite was phosiasite aggregates having a particle size of 10μ or more.
When this faujasite was heated at 900°C for 2 hours, the surface area decreased by only 8%.

Claims (1)

[Claims] 1. Does not contain a binder, has a lattice constant of 24.35 to 24.55 A as determined by powder X-ray diffraction, and has at least
Ultra-stable phagiasite-type zeolite consisting of 80wt% zeolite aggregates with a diameter of 10μ or more. 2. The faujasite-type zeolite according to claim 1, wherein at least 80 wt% is zeolite aggregates having a diameter of 50 to 300 μ. 3 (a) Aluminum as Al ₂ O ₃ 10-16wt%
(anhydrous basis) By crystallizing a homogeneous compound of granular amorphous aluminosilicate containing granular amorphous aluminosilicate in an aqueous alkali metal hydroxide solution, synthesize phasiasite-type zeolite aggregates with a particle size of 10μ or more, and (b) by ion exchange. After reducing the alkali metal content of the aggregate to 5 wt% or less as an oxide, (c) calcining the ion-exchanged aggregate at a temperature of 600 to 800 °C until the lattice constant of the zeolite becomes 24.60 A or less. , (d) ion-exchange the calcined zeolite aggregate using an H-type ion exchange resin or ammonium salt aqueous solution to reduce the alkali metal content of the zeolite to 1 wt% or less as an oxide; (e) then ( The zeolite obtained in step d) is calcined at a temperature of 300 to 700°C, does not contain a binder, has a lattice constant of 24.35 to 24.55 A as determined by powder X-ray diffraction, and is at least 80 wt%. A method for producing ultra-stable phagiasite-type zeolite consisting of zeolite aggregates with a diameter of 10μ or more.