JPH0761859B2 - Calcination method of ammonium-exchanged phosjadite type zeolite - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a faujasite-type zeolite having high activity and high hydrothermal resistance.

Zeolites with large cavities, which are classified as faujasite-type zeolites (hereinafter referred to as faujasites), are used as solid acid catalysts in processes such as fluid catalytic cracking, hydrocracking, and alkylation, or as a component thereof. Widely used. Not only faujasite, the performance generally desired as a zeolite-containing catalyst is
Much depends on the hydrothermal stability of zeolite. Faujasite, which has good catalytic activity, is slightly inferior in hydrothermal stability.

In general, the stability of zeolite with respect to heat, steam, and acid increases as the SiO ₂ / Al ₂ O ₃ molar ratio increases and the content of the alkaline component as the cationic species of the zeolite decreases.

[Prior Art] In the case of mordenite having a relatively high SiO ₂ / Al ₂ O ₃ molar ratio,
The hydrothermal stability of mordenite can be improved by directly treating with an acid solution to remove alkali components and eluting aluminum.

However, since faujasite has a lower SiO ₂ / Al ₂ O ₃ molar ratio than mordenite, crystal structure destruction occurs when treated directly with an acid solution, so the method treated with a direct acid solution is hydrothermally stable. It is not possible to give the sex.

Reduces the alkali component of faujasite and SiO ₂ / A
A known technique for imparting hydrothermal stability by increasing the l ₂ O ₃ molar ratio to structurally stabilize it is to carry out ammonium ion exchange of alkali metal type faujasite to partly change it to ammonium type faujasite. After that, it is calcined to form hydrogen-type faujasite, and then this faujasite is exchanged with ammonium ion again to obtain ammonium-type faujasite in which the alkali metal in the faujasite is further reduced. A method of increasing the SiO ₂ / Al ₂ O ₃ molar ratio by treating with a solution to elute aluminum is adopted, and an alternative method is also used.

For example, after the alkali metal or alkaline earth metal (= alkaline component) type faujasite is maintained at pH 4.5 to 5.0 by the addition of ammonia water and ammonium ion exchange is performed with an aqueous ammonium salt solution to an exchange rate of 50 to 67%, Hydrogen-type faujasite obtained by firing at a temperature of 400 to 600 ° C for 2 to 4 hours was treated with an aqueous ammonium salt solution while (1) acid was added to maintain the pH at 2.5 to 4.5. A method in which alkaline components in the site are removed and aluminum is eluted at the same time and then baked (JP-A-60-46916), or (2) ammonium water is added while maintaining pH at 4.5 to 5.0 by adding aqueous ammonia. After treatment with an aqueous solution, solid-liquid separation and washing to remove alkaline components, then treatment with a strongly acidic cation exchange resin, converting to hydrogen type, and elution of aluminum and baking (JP-A-60-4691
7) etc.

[Problems to be Solved by the Invention] In any case, in these known methods, the number of steps is large, it is necessary to add an acid or alkali for pH adjustment, and control for pH adjustment is required. Not only is the process complicated, but it is economically disadvantageous.

[Means for Solving Problems] As a result of intensive investigations by the present inventors in order to solve the drawbacks of these known methods, the hydrogen-type faujasite was obtained by firing ammonium-type faujasite containing chlorine (Cl) ions. We have discovered the fact that the one made of jacite can easily elute aluminum from zeolite by treatment with an aqueous ammonium salt solution or a strong acid cation exchange resin.

That is, when the ammonium-exchanged faujasite-type zeolite is calcined, the hydrogen-type faujasite obtained by calcining Cl ions in the zeolite in a steam atmosphere is simply an ammonium salt aqueous solution, or a strong acidic cation. They have found that the reduction of alkali components and the elution of aluminum can be achieved all at once by only performing the treatment with an ion exchange resin, and reached the present invention.

The present invention, when firing an ammonium-exchanged faujasite-type zeolite, has never been carried out before in Cl.
By an extremely simple operation of firing in the presence of ions, it is possible to provide a firing method capable of increasing the SiO ₂ / Al ₂ O ₃ molar ratio without destroying the crystal structure, that is, imparting hydrothermal stability. is there.

The reason is that hydrogen-type faujasite obtained by calcining ammonium ion-type faujasite in the presence of Cl ions reduces the alkali component and elutes aluminum only by treating with ammonium salt solution or strong acid cation exchange resin. Although it is not clear whether it can be done very easily, it is interpreted as follows.

The change in the crystal structure due to the firing treatment of ammonium exchange faujasite is generally due to the fact that part of the Al constituting the crystal is hydrolyzed and released, and a new Si-O-Si Bonds are formed, so that the lattice shrinks, a so-called stabilization reaction occurs, structurally stabilizes, and the SiO ₂ / Al ₂ O ₃ molar ratio constituting the crystal increases substantially, resulting in hydrothermal stability. Is said to improve.

In this way, the Al of the crystal lattice is desorbed by hydrolysis and a new
The presence of Cl ions during the stabilization reaction that forms the Si-O-Si bond promotes the hydrolysis of Al, and the Al released from the lattice contacts the ammonium salt aqueous solution or strongly acidic cation exchange resin. It is thought that it is because it has changed to a form that can be easily eluted with. In fact, in the experiments of the present inventors, it was found that hydrogen type faujasite obtained by similarly baking ammonium type faujasite containing substantially no Cl ion was similarly treated with an aqueous solution of ammonium salt or a strongly acidic cation exchange resin. SiO ₂ / Al ₂ O ₃ molar ratio of faujasite is does not become too high, while the dissolution rate of aluminum is at most about 10%, very easily be more than 40% at firing method according to the invention I understood.

Further details will be described.

In the present invention, the faujasite-type zeolite as a raw material includes X-type zeolite having a SiO ₂ / Al ₂ O ₃ molar ratio of _{2 to} 3.5 and Y-type zeolite of 3.5 or more, and any zeolite may be used. Alternatively, either synthetic zeolite can be used. Usually, these zeolites contain alkali metals or alkaline earth metals as cationic species. As the zeolite used as a catalyst, synthetic zeolite is mainly used because of its advantages of purity and uniformity, but synthetic zeolite is usually synthesized as a cation species in the form of sodium. Prior to calcination, it is necessary to perform ammonium exchange of an alkaline component, which is a cationic species of zeolite, with an aqueous ammonium salt solution. For example, ammonium salts include NH ₄ Cl, (NH ₄ ) ₂ SO ₄ , and CH ₃ COONH ₄ . The ion exchange rate is an important factor for carrying out the present invention. When the ion exchange rate is low, the decrease in crystallinity and the stabilization reaction are likely to be insufficient during firing, and then an ammonium salt aqueous solution or a strongly acidic cation exchange resin is used. When treated, it becomes difficult to reduce the amount of alkali components, and the elution of aluminum becomes insufficient. Therefore, the ammonium exchange rate is preferably 50% or more.

The ammonium-type faujasite obtained by exchanging the alkali component with ammonium in this way is usually filtered and washed to sufficiently remove the adhering mother liquor, and then dried. Is an important factor
It is necessary to introduce Cl ions. As a method of introducing Cl ions, addition of NH ₄ Cl as a Cl ion source is the most effective in carrying out the present invention, and the process is efficient. That is, the treatment step of ion-exchanging the alkaline component, which is the cation species of zeolite, to ammonium type, if NH ₄ Cl is used as the ammonium salt source, filtration after the exchange and washing of the zeolite in the washing step are appropriately performed,
In other words, if the mother liquor consisting of NH ₄ Cl is partially adhered and dried, the resulting ammonium-type faujasite will contain Cl.
Ions can be introduced easily and uniformly. The amount of Cl ions introduced is preferably 0.01 wt% or more, and more preferably 0.02 wt% or more, as Cl based on the dry weight of ammonium-type faujasite. In the case of carrying out the ammonium exchange using an ammonium salt other than NH ₄ Cl, it may be dried after the required amount of NH ₄ Cl before separately dried. The ammonium-type faujasite containing Cl ions that have been dried may be fired in a steam atmosphere. The calcination conditions may be such that calcination is performed at a temperature and for a time sufficient to shrink the lattice constant of the zeolite to a target value, and these temperatures and times are usually 400 to 900 ° C.
Preferably, 500 to 800 ° C and 0.2 to 5 hours are sufficient. However, at the time of firing, in order to promote the stabilization reaction without destroying the crystal, it is preferable to use 10 vol% of steam in a steam atmosphere.
It is necessary to fire in an atmosphere containing the above. The water content may be so-called self-steaming using the water adsorbed by the zeolite itself, or may be introduced from the outside.

EFFECTS OF THE INVENTION Hydrogen-type faujasite obtained by firing ammonium-type faujasite containing Cl ions by the firing method according to the present invention is simply an ammonium salt aqueous solution or a strongly acidic cation exchange resin and a slurry. The alkaline component in the faujasite can be reduced to the extent that it does not substantially affect the hydrothermal resistance simply by contacting in the state, and the target is a high hydrothermally stable SiO ₂ / Al ₂ O ₃ molar ratio high ratio. You can get jasite.

As described above, the present invention is a manufacturing method that is simple in process and good in productivity and is industrially extremely advantageous.

[Examples] The method of the present invention will be specifically described below with reference to Examples. In the examples, Y-type zeolite is abbreviated as Y.

Comparative Example 1 Synthesis of SiO ₂ / Al ₂ O ₃ molar ratio of 5.5 Na—Y was ion-exchanged twice at 80 ° C. with 10 wt% NH ₄ Cl aqueous solution, solid-liquid separation was performed, and Cl was observed using pure water. It was thoroughly washed until it disappeared, and then dried at 100 ° C. The exchange rate of the obtained NH ₄ -Na-Y is 73.
The Cl content in% was below the detection limit.

This NH ₄ —Na—Y was calcined at 750 ° C. for 1 hour. NH ₄ -H obtained
-For 100 g of Y, 600 ml of pure water and H-type strong acid cation exchange resin Amberlite 200c (made by Rohm and Haas)
After adding 150 ml and stirring at 80 ° C for 2 hours, only the resin was separated and 150 ml of H-type ion exchange resin was added again,
The mixture was stirred at 0 ° C for 2 hours. After separating the zeolite, it was dried. The obtained zeolite had a SiO ₂ / Al ₂ O ₃ molar ratio of 5.7 and a Na ₂ O content of 0.3 wt%. This zeolite 1
When heat-treated at 700 ° C. for 5 hours in a 00% steam atmosphere, the decrease in crystallinity was 41%.

Example 1 Synthesis with SiO ₂ / Al ₂ O ₃ molar ratio of 5.5 Ion exchange was performed twice at 80 ° C. using a 10 wt% NH ₄ Cl aqueous solution, and then solid-liquid separation was performed. It was then washed briefly and dried at 100 ° C. The exchange rate of the obtained NH ₄ -Na-Y was 73%, and the Cl content was 0.06 wt%.
Met. This NH ₄ —Na—Y was calcined at 750 ° C. for 1 hour in a steam atmosphere. Pure water 600m against the obtained Na-H-Y 100g
l and H type strong acid cation exchange resin Amberlite 200
After adding 150 ml of C (made by Rohm and Haas) and stirring at 80 ° C. for 2 hours, only the resin was separated, 150 ml of H-type ion exchange resin was added again, and the mixture was stirred at 80 ° C. for 2 hours. The zeolite was separated and dried. Si of the obtained zeolite
The O ₂ / Al ₂ O ₃ molar ratio was 9.7 and the Na ₂ O content was 0.3 wt%. 5% of this zeolite at 700 ℃ in 100% steam atmosphere
After heat treatment for an hour, the decrease in crystallinity was only 5%.

Comparative Example 2 The NH ₄ -Na-Y containing no Cl ion prepared in Comparative Example 1 was added to 580
Calcination was carried out for 2 hours. Pure water against 100 g of the obtained Na-H-Y
600 ml and 50 g of NH ₄ Cl were added and the mixture was stirred at 80 ° C. for 2 hours.
After solid-liquid separation of the slurry, 600 ml of pure water and NH ₄ Cl were added again.
50 g was added and the mixture was stirred at 80 ° C. for 2 hours. After solid-liquid separation, it was washed, dried at 100 ° C., and then calcined at 500 ° C. for 2 hours to obtain a hydrogen-type zeolite. The obtained zeolite had a SiO ₂ / Al ₂ O ₃ molar ratio of 5.6 and a Na ₂ O content of 0.3 wt%.

When this zeolite was heat-treated at 700 ° C. for 5 hours in a 100% steam atmosphere, the decrease in crystallinity was 37%.

Example 2 NH ₄ —Na—Y containing 0.08 wt% of Cl and having an ammonium exchange rate of 73% was prepared in the same manner as in Example 1. This NH ₄ —Na—Y was calcined at 580 ° C. for 2 hours in a steam atmosphere. To 100 g of the obtained Na-H-Y, 600 ml of pure water and NH ₄ Cl
50 g was added and the mixture was stirred at 80 ° C. for 2 hours. After solid-liquid separation of the slurry, 600 ml of pure water and 50 g of NH ₄ Cl were added again, and
The mixture was stirred at 0 ° C for 2 hours. After solid-liquid separation, it was washed, dried at 100 ° C, and calcined at 500 ° C for 2 hours to obtain a hydrogen-type zeolite. The obtained zeolite had a SiO ₂ / Al ₂ O ₃ molar ratio of 9.3 and a Na ₂ O content of 0.2 wt%.

When this zeolite was heat-treated in a 100% steam atmosphere at 700 ° C. for 5 hours, the decrease in crystallinity was only 3%.

Claims (2)

[Claims] 1. A method for calcination of an ammonium-exchanged faujasite-type zeolite, which comprises calcining an ammonium-exchanged faujasite-type zeolite in a steam atmosphere with chlorine ions coexisting in the zeolite. 2. Chloride ions in ammonium-exchanged faujasite-type zeolite having an ammonium exchange rate of 50% or more.
The firing method according to claim 1), wherein the firing is performed at 400 to 900 ° C. for 0.2 to 5 hours in an atmosphere containing 0.01 vol% or more of steam and 10 vol% or more of steam.