JPH0679170A - CaA-type zeolite molded body and method for producing the same - Google Patents

Abstract

(57) [Summary] [Composition] A CaA-type zeolite molded product containing 10 parts by weight or more of a binder with respect to 100 parts by weight of CaA-type zeolite ion-exchanged with Ca ions of 40% or more and less than 70%, and the molded product. Adsorbent. [Effect] It has excellent heat resistance as well as adsorption properties.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CaA type zeolite compact and an adsorbent comprising the same. Ca
The A-type zeolite has excellent gas adsorption performance, and includes, for example, selective adsorption separation of n-paraffins from a hydrocarbon mixture and n-butane-producing raw material from a butane-butylene fraction.
-Widely used for separation of butylene, separation and purification of pure oxygen from mixed gas of oxygen and nitrogen.

[0002]

2. Description of the Related Art Conventional CaA-type zeolite is a molecular sieve having a Ca ion exchange rate of 70% or more and a pore size of about 5 angstroms. The higher the Ca exchange rate, the higher the adsorption capacity and the excellent adsorption characteristics. It is said that on the other hand,
In the case of JP-A-58-196847, by adding 1% by weight or more of aluminum hydroxide, the Ca ion exchange rate becomes 1
It is said that when it is 5% or more, it becomes an adsorbent excellent in O ₂ / N ₂ separation performance at low temperature.

[0003]

The CaA-type zeolite needs to be heat-treated at 300 ° C. or higher in order to remove water in the pores at the time of production. Has severe deterioration of the adsorption characteristics due to high temperature and high moisture atmosphere, and the deterioration of the adsorption characteristics cannot be practically suppressed by the conventional CaA-type zeolite.

The present invention has solved such a problem, that is, the heat resistance is remarkably higher than that of the conventional CaA type zeolite, and it is -10 ° C without adding aluminum hydroxide.
The object of the present invention is to provide a CaA-type zeolite and a molded product thereof, which are extremely excellent in adsorption performance in a wide temperature range of 25 to 25 ° C.

[0005]

The present inventors have found that in order to improve the adsorption performance of CaA-type zeolite, it is not necessary to make the Ca ion exchange rate close to 100% or to add aluminum hydroxide, and 70% If it is less than 40%, it is sufficient if it is 40% or more. By adjusting such a Ca ion exchange rate, it is possible to increase the adsorption capacity in practical use without deteriorating the adsorption performance; and Ca ion exchange rate 70 It has been found that the CaA type zeolite of less than 50% has very excellent heat resistance as compared with that of 70% or more.
That is, the present invention is composed of the CaA-type zeolite ion-exchanged by 40% or more and less than 70% with Ca ion and a binder, and contains 10 parts by weight or more of the binder per 100 parts by weight of the CaA-type zeolite, CaA-type The gist is a zeolite compact and the CaA-type zeolite compact.

The present invention will be described in detail below.

Ca of the CaA type zeolite compact of the present invention
The ion exchange rate must be in the range of 40% or more and less than 70%. If the Ca ion exchange rate is 40% or less, the gas adsorption capacity is low; if it is 70% or more, the heat resistance is poor;
If it is 40% or more and less than 70%, a substantially high gas adsorption capacity and excellent heat resistance can be maintained. It is surprising that the revealed Ca ion exchange rate of less than 70% improves heat resistance without lowering the adsorption capacity. At a low ion exchange rate of less than 70%, the size of the pores is smaller than that of a high ion exchange rate of 70% or more, and the gas adsorption / desorption rate is extremely low. Has been said. However, it has been found that the CaA-type zeolite molded product of the present invention has no significant difference in the adsorption / desorption rate when the Ca ion exchange rate is 40% or more. Among the CaA type zeolite compacts of the present invention, those having a Ca ion exchange rate of 50 to 60% are particularly excellent in both gas adsorption performance and heat resistance.

The binder of the CaA-type zeolite molded product of the present invention is 1 per 100 parts by weight of the CaA-type zeolite.
Must be 0 parts by weight or more. When the amount of the binder is less than 10 parts by weight, molding is difficult, and even if molding is possible, sufficient molded product strength cannot be obtained, which is not preferable. However,
Excess binder not only lowers the zeolite content, but also closes the zeolite pores and reduces the adsorption properties. Specifically, if it exceeds 30 parts by weight, the gas adsorption capacity becomes too low, which is not preferable, and 30 parts by weight or less is preferable. Further, in order to obtain sufficient strength of the molded body, it is preferably 15 parts by weight or more. The CaA type zeolite molded article of the present invention has a gas adsorption capacity of, for example, a temperature of −10 ° C. and a pressure of 70.
25 to 37 when nitrogen gas is used at 0 torr
Ncc / g.

Since the CaA type zeolite molded article of the present invention has an adsorption performance due to the original performance of the zeolite, the kind of the binder used is not particularly limited. It is preferable to use a binder having a good binding property. For example, attapulgite-type clay,
Montmorillonite type clay and kaolinite type clay are used.

The CaA-type zeolite compact of the present invention is produced by a known method, for example, NaA-type zeolite synthesized from sodium aluminate and sodium silicate, that is, 4A-type zeolite as a starting material, and the powder of the A-type zeolite is CaCl ₂ , ion-exchanged with a solution containing Ca ions, such as _{Ca (OH) 2, Ca (} NO 3) 2, a binder / zeolite weight ratio is mixed with a binder in a ratio which is a 10-30 / 100, molded, fired Or; 4A
Type zeolite powder after the following ion exchange binder /
Mixing with a binder in a ratio such that the weight ratio of zeolite is 10 to 30/100, molding and firing, CaCl ₂ , Ca (O
It is completed by adjusting the Ca ion exchange rate to 40% or more and less than 70% with a solution containing Ca ions such as (H) ₂ and Ca (NO ₃ ) ₂ .

Further, the pH of the solution during this Ca ion exchange
Is preferably 7 or more. This is because in a pH of less than 7, that is, in an acidic atmosphere, zeolite crystals become unstable, defects occur in the crystal structure, or the crystal structure itself collapses, resulting in a marked decrease in the gas adsorption capacity.

Next, a method for producing the CaA type zeolite compact will be described.

First, the NaA-type zeolite powder or the CaA-type zeolite powder prepared by the above method is kneaded with a binder to form a compact having an appropriate size. On this occasion,
If necessary, a small amount of a molding aid may be added to improve the moldability. The shape of the molded body may be columnar, spherical, or the like, but is not particularly limited.

At this time, the binder kind is not particularly limited, but one having good sinterability is preferable, and the binder amount is 10 parts by weight or more, preferably 30 parts by weight with respect to 100 parts by weight of zeolite (calculated as CaA type zeolite). It is added so as to be not more than the weight part.

Before the subsequent firing, the pellets thus obtained are preferably dried by a conventional method, that is, at 100 ° C. to 120 ° C. until the water content in the molded body becomes about 20% by weight or less.

The dried pellets are sintered and baked well. For example, when kaolin-based clay is used as a binder, firing is performed so that the kaolin-based clay is well baked and hardened 55.
It is preferable to carry out at 0 ° C. or higher and 700 ° C. or lower at which zeolite crystals are not affected. Sintering time of 2 hours or more is sufficient. By firing under such conditions,
All the organic substances and molding aids in the kaolin-based clay are burnt and disappeared, and the binder is sufficiently baked and solidified.

When NaA type zeolite is used as a raw material for the molded body, CaCl ₂ , Ca (OH) ₂ , C
The ion exchange rate is adjusted to 40% or more and less than 70% with a Ca ion solution such as an a (NO ₃ ) ₂ aqueous solution.

The pH of the solution at the time of Ca ion exchange is 7
The above is preferable. This is because the zeolite crystals become unstable at a pH of less than 7, that is, in an acidic atmosphere, defects occur in the crystal structure, or the crystal structure itself collapses, and the gas adsorption performance remarkably decreases.

At this time, as a pretreatment for the ion exchange, it is preferable that the calcined NaA type zeolite compact is moistened to at least 20% by weight so that the gas adsorbed through the pores is desorbed. This operation is to crack the pellets during ion exchange in the Ca ion solution,
Useful for eliminating cracks.

Subsequent to the ion exchange, calcination and activation are carried out in the range of a minimum temperature of 300 ° C. at which structural water in the zeolite compact can be removed to a maximum temperature of 700 ° C. at which zeolite crystals do not collapse.

[0021]

It is well known that the higher the Ca ion exchange rate, the more the CaA type zeolite has adsorbed sites for the Ca ion adsorption, so that the adsorption amount increases. On the other hand, CaA-type zeolite forms structural water during ion exchange and cannot be easily removed even when dried. Since this structured water coordinates with Ca ions at the adsorption site, it increases as the Ca ion exchange rate increases. This structured water is one of the factors that influence the adsorption performance, and when the Ca ion exchange rate is 70% or more, it reacts with the aluminosilicate of the zeolite skeleton by heat treatment and reduces the adsorption amount.

Usually, in order to remove this water, the temperature is 300 ° C.
The CaA-type zeolite is fired and activated at 700 ° C. or lower. At this stage, the reaction of the aluminosilicate of the zeolite skeleton with the structured water proceeds, and the amount of adsorption is significantly reduced. In extreme cases, this water causes a de-Al reaction and destroys the zeolite framework. When the Ca ion exchange rate is 70% or more, it is practically impossible to suppress the formation of this structured water and the reaction with the zeolite skeleton.

However, when the Ca ion exchange rate is less than 70%, the structured water can be removed by the usual drying method and firing method.

[0024]

As is apparent from the above description, the CaA-type zeolite molded product of the present invention has remarkably excellent adsorption properties and heat resistance as compared with those manufactured by the conventional technique. Thus, for example, oxygen PSA, TP
Useful for improving the efficiency of gas adsorption and separation of SA.

[0025]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

Various measuring methods in Examples and Comparative Examples are as follows. <Method for measuring nitrogen adsorption capacity> The nitrogen adsorption capacity was measured by the volume method. The zeolite molded body is activated at 350 ° C. for 120 minutes under a pressure of 0.01 mmHg or less, and after cooling, nitrogen gas is introduced, adsorption temperature −10 ° C., adsorption pressure 700 mmH.
g, and the adsorption capacity (Nc
c / g) was measured. <Oxygen PSA performance measurement method> Dry air is adsorbed at a temperature of 25 ° C. for a cycle time of 1 min at an adsorption pressure of 0.2 kgf / cm ₂ and desorbed at 185 torr to refine the oxygen concentration to 93% for 1 hour. The amount of oxygen purified per 1 kg is taken as the amount of oxygen taken out (Nl / kg · h), and the amount of oxygen purified relative to the amount of oxygen contained in air is the oxygen recovery rate (%)
Was measured as. <Molded Body Strength Measuring Method> The molded body strength was measured using a Kiya type hardness meter. At this time, the average of the measured strength values of 100 molded articles was taken as the molded article strength.

"Parts" in the following specific examples are by weight.

Example 1 100 g of 4A type synthetic zeolite powder (Zeolam 4-A powder: manufactured by Tosoh Corporation) was subjected to ion exchange at 60 ° C. for 3 hours in 1000 ml of an aqueous calcium chloride solution containing 0.35 mol of Ca ions. The ion exchange rate of the zeolite after washing and removing the attached water was examined by atomic absorption.
%, And the balance was sodium ion.

The nitrogen adsorption capacity of this product was evaluated by the above method and was found to be 39.5 Ncc / g.

25 parts of kaolinite-type clay was mixed with 100 parts of this zeolite powder, and a granulator (muller mi) was used.
xer) while adjusting the water content and kneading and kneading. Next, this kneaded product was supplied to an extrusion molding machine equipped with a die plate having a diameter of 1.5 mm to perform extrusion molding into a columnar shape.
After drying at 120 ° C., the length was adjusted to 5 to 10 mm and firing was performed at 650 ° C. for 4 hours using a muffle furnace.

When the nitrogen adsorption capacity and pressure resistance of this product were evaluated by the above-mentioned methods, it was 32.5 Ncc / g, 3.2.
It was kg. When the oxygen PSA performance was evaluated by the above method, the oxygen extraction amount was 53.1 Nl / kg · h and the oxygen recovery rate was 45.3%.

Examples 2 to 4 Comparative Examples 1 to 3 A type zeolite molding of each Ca ion exchange rate shown in Table 1 was carried out by exactly the same operation as in Example 1 except that the Ca ion amount and the binder amount were changed. Each body was prepared. Table 1 shows the results of evaluation of those physical properties by the same method as in Example 1.

From these nitrogen adsorption capacity measurement results and oxygen PSA performance measurement results, it is understood that the molded article of the present invention has excellent adsorption characteristics in the temperature range of -10 ° C to 25 ° C.

Example 5 25 parts of kaolinite clay was mixed with 100 parts of 4A type synthetic zeolite powder (Zeorum 4A powder: manufactured by Tosoh Corporation) and kneaded while adjusting water content in a granulator (muller mixer). I kneaded. Next, this kneaded product was supplied to an extrusion molding machine equipped with a die plate having a diameter of 1.5 mm to perform extrusion molding into a columnar shape. After drying at 120 ℃, adjust the length to 5-10mm and use a muffle furnace to
It was calcined at 0 ° C. for 4 hours.

After cooling, 125 g of this molded body was hydrated and degassed, and then ion-exchanged for 3 hours at 60 ° C. in 1000 ml of an aqueous calcium chloride solution containing 0.12 mol of Ca ions. The molded body, which had been washed and freed from adhering water, was dried at 120 ° C. and fired and activated at 400 ° C. for 1 hour. When the ion exchange rate of the thus obtained zeolite molded product was examined by atomic absorption, it was 51%, and the remainder was sodium ion.

When the nitrogen adsorption capacity and pressure resistance of this product were evaluated by the above-mentioned methods, they were 32.7 Ncc / g, 3.2.
It was kg. When the oxygen PSA performance was evaluated by the above-mentioned method, the oxygen extraction amount was 53.5 Nl / kg · h and the oxygen recovery rate was 45.6%.

Examples 6 to 8 Comparative Examples 4 to 6 By the same operations as in Example 5, Ca-NaA type zeolite compacts having the binder content and Ca ion exchange rate shown in Table 3 were prepared. Table 1 shows the results of evaluation of those physical properties by the same method as described above.

Table 1 Ca Io Ion Vine Nitrogen Adsorption Oxygen Extraction Oxygen Recovery Oxygen Recovery Pressure Resistance Strength Exchange Rate Dar Volume Volume Volume Mol% Part Ncc Nl /% kgf / g kgh Example 2 0.26 42 25 26.9 51.3 45.8 3.5 3 0.48 58 25 33.2 53.4 45.7 3.3 4 0.85 64 25 29.1 51.9 45.9 3.1 Comparative Example 1 0.17 31 25 20.2 33.5 37.1 3.4 2 2.50 89 25 22.0 48.5 40.5 3.4 3 0.35 51 5 33.4 63.1 43.5 0.5 Example 6 0.26 42 25 27.1 51.9 45.6 3.4 7 0.48 58 25 33.6 53.5 45.8 3.1 8 0.85 64 25 29.8 51.8 45. 7 3.2 Comparative example 4 0.17 312 20.5 37.8 37.5 3.4 5 2.50 89 25 22.4 48.1 40.7 3.2 6 0.35 51 5 33.5 63.3 43.6 0.5

Claims (2)

[Claims] 1. To 100 parts by weight of CaA-type zeolite ion-exchanged with Ca ions of 40% or more and less than 70%,
A CaA-type zeolite molded product containing 10 parts by weight or more of a binder. 2. An adsorbent comprising the molded article according to claim 1.