JPH01108113A - Production of silanized zeolite - Google Patents

Abstract

PURPOSE:To produce a silanized zeolite having an inlet pore diameter precisely controlled at an arbitrary size, by silanizing a humidified alkali or alkaline-earth metal-type zeolite with a specific organic silane compound diluted with a hydrophobic solvent and calcining the product. CONSTITUTION:An alkali or alkaline-earth metal-type zeolite (e.g. mordenite) is left standing in a room, adsorbed with steam or immersed in water to effect the saturated adsorption of the pore with water and is heated at 50-100 deg.C to dry the outer surface and obtain a zeolite adsorbed with water. The zeolite is silanized by contacting with a hydrophobic solvent (e.g. n-hexane) containing <=10vol.% of an organic silane compound of formula (y is 1-4; X is 1-10C alkyl, aryl, arylalkyl or H; R is 1-10C alkoxy), washed, filtered and calcined at 100-600 deg.C for 2-20hr.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing silanized zeolite, and more specifically, after absorbing moisture in zeolite and filling the pores in the crystal with water, the zeolite crystal is The present invention relates to a method for producing a silanized zeolite whose outer surface is silanized with an organic silane compound to arbitrarily precisely control the pore entrance diameter.

[Prior art and its problems] Zeolite is a porous silica-alumina crystal.
) It has the physical and chemical characteristics of adsorbing water and organic substances well, 2) it is a cation exchanger, and 3) it has uniform pores and has molecular sieving properties, so it is often used as a solid catalyst or adsorbent. is known for its industrial uses.

The most common use as a solid catalyst is as a petroleum crab king catalyst, which utilizes the cation exchange properties of zeolite. When zeolite's sodium cations are replaced with protons, alkaline earth metals such as calcium, or rare earth elements such as lanthanum, it exhibits extremely strong solid acid properties.

On the other hand, as an adsorbent, separation of n-1i-paraffin,
It is used for drying naphtha decomposition gas, etc., and all of these utilize the molecular sieving action of zeolite.

As described above, when using zeolite as an adsorbent, the pore diameter is an important factor, and a technique for arbitrarily controlling the pore diameter is desired.

As an example, a method is known in which cations are exchanged in A-type zeolite with alkali metals or alkaline earth metals to change the pore diameter depending on the size of the cations.
With this method, changes can only be made by one person.

Other methods have been proposed, such as supporting an organic silane compound on zeolite and firing the supported material to form silica. When a silanizing agent with a small molecular diameter is used, the inside of the pore is silanized before the pore diameter can be controlled, resulting in the inconvenience of clogging the pore. Therefore, it is necessary to use a silanizing agent that has a relatively large molecular diameter and does not enter the zeolite pores, and for zeolites with large pore diameters such as faujasite There was a problem that a silanizing agent had to be used, which was not necessarily economical in terms of equipment, reagents, etc.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems and produces silanized zeolite, which is produced by silanizing only the outer surface of the zeolite crystals and precisely controlling the pore entrance diameter, uniformly and in large quantities. The purpose is to provide a method for manufacturing.

[Means for solving the problems] In order to solve the above problems, we have conducted various research into techniques for precisely controlling the pore entrance diameter by silanizing only the outer surface of the zeolite crystals. By adopting a method in which zeolite is first made to absorb moisture and then silanized in a liquid phase, the present invention has been completed which solves the above-mentioned problems.

That is, the method for producing silanized zeolite is characterized in that an alkali or alkaline earth metal ion type zeolite is made to absorb moisture, is silanized in a liquid phase with an organic silane compound diluted with a hydrophobic solvent, and then calcined.

The present invention will be explained in more detail below.

The zeolite used in the present invention is an alkali or alkaline earth metal ion type zeolite,
X-type zeolite, Y-type zeolite, ZSM-5, ZSM
-41, mordenite, etc. are particularly preferred.

In the present invention, water is adsorbed on the zeolite, but the method is not particularly limited, and the pores are finally filled with water by leaving the zeolite indoors, absorbing water vapor, or immersing it in water. Adsorb to saturation. In this case, it is necessary that the pores within the zeolite crystals be completely filled with water. Furthermore, since the silanizing agent is wasted due to the water present on the outer surface of the crystal, it is preferable to dry the outer surface to remove some amount of water adhering to the surface. This drying is usually preferably carried out at 50 to 100°C.

Silanization is carried out by bringing the zeolite that has adsorbed water in this way into contact with a silanizing agent diluted with a hydrophobic solvent.

As the hydrophobic solvent used in the present invention, paraffinic hydrocarbon solvents such as hexane, heptane, and octane, cycloparaffinic hydrocarbon solvents such as cyclohexane, and aromatic hydrocarbon solvents such as benzene and toluene are preferably used.

The organic silane compound used as a silanizing agent in the present invention includes 5iRyXa-y [where y is an integer of 1 to 4, X is a C1 to C1O alkyl group, aryl group, arylalkyl group, or hydrogen, R
represents an alkoxy group of 01 to CIO, respectively], and tetramethyl orthosilicate is particularly preferably used.

This organic silane compound is used after being diluted with a hydrophobic solvent.

Although its concentration may be quite high, it is preferably used at a concentration of 1% by volume or less.

The method of contacting the zeolite with the silanizing agent is preferably a batch method, and the degree of silanization can be arbitrarily changed by changing the temperature, concentration, and contact time.

After finishing the silanization, washing, filtration and calcination are performed.

This firing is carried out in an air atmosphere for 60 minutes in a commonly used electric furnace.
It is preferable to bake at a temperature of 0°C or lower, and more preferably a temperature of 100 to 6
Preferably, the firing is carried out in a temperature range of 00°C. Further, the firing time is preferably 2 hours or more, and more preferably 2 to 20 hours.

In the present invention, by completely filling the pores in the zeolite crystal with water, the silanizing agent is prevented from entering the pores, while the water present on the outer surface of the zeolite crystal is suppressed. acts as a hydrolyzing agent for the silanizing agent.

Further, by using a silanizing agent diluted with a hydrophobic solvent, a silanizing reaction occurs at the interface between water and the silanizing agent (ie, the outer surface of the zeolite). Through this silanization reaction and subsequent calcination, the pore entrance diameter is controlled by the silica layer formed on the outer surface of the zeolite, and shape selectivity is developed.

[Examples] Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples.

Example I Na-type Y zeolite (Na-Y) was left indoors to absorb moisture in the atmosphere to saturation, and then dried at 50° C. for about two days and nights. A portion of the sample thus obtained was fired at 500°C and the weight loss due to firing was measured to determine the amount of water absorbed, which was 0.30 (g-
H20/g-dry zeolite).

Next, tetramethyl orthosilicate (hereinafter referred to as TMO8) diluted to 1-10% by volume with n-hexane was used as a silanizing agent, and the silanizing agent was added at a ratio of 5 mJ to the hygroscopic zeolite Ig, Liquid phase silanization was performed by immersion at room temperature. next,
The zeolite was collected by filtration, dried at 80°C, and then calcined in air at 500°C for about 5 hours.

Here, the TMO5 concentration and silanization reaction time were varied, and 7M was reacted per 1 g of zeolite.
Six silanized zeolites with different amounts of O8 (loaded amount) were prepared.

Regarding the silanized zeolite obtained in this way,
The amount of single component adsorption of various aromatic components was measured, and the relationship between the amount of TMO3 impregnated and each adsorption amount is shown in FIG.

Benzene (BZ) as an aromatic component, 1. :(,5
-trimethylbenzene (TMB), 1. L5-)lyisopropylbenzene (TIPB) was used.

As the amount of T M OS IAM increases, the amount of adsorption decreases in the order of components with larger molecular diameters.

Here, the adsorption amount of each component does not gradually decrease as the amount of TMO8 impregnated increases;
It decreases rapidly after reaching the adhesion level. This rapid decrease is considered to indicate that the pore entrance diameter is controlled relatively uniformly.

From the above, it can be seen that as the amount of TMO8 impregnated increases, the pore entrance diameter becomes gradually narrower.

Example 2 For the silanized zeolite prepared in Example 1, a two-component system competitive adsorption experiment of aromatic components with different molecular diameters was conducted, and the relationship between the amount of TMO3 impregnated and the adsorption ratio of each aromatic was determined in a second manner.
Shown in Figures (a) to (c).

Here, as binary aromatics, l) m-xylene (mX) ~BZ system, 2) mX-TMB system, 8) T
Evaluation was performed using the above three types of MB-TIPB-based solutions.

These results show that in any system, as the amount of TMO8 impregnated increases, the adsorption ratio of components with small molecular diameters increases, that is, shape selectivity gradually appears.

Comparative Example 1 Na-Y dried by calcination at 500°C was subjected to liquid phase silanization using TM01 in the same manner as in Example 1 without absorbing moisture.

Here, three types of silanized zeolites with different amounts of TMO8 impregnated were prepared.

Competitive adsorption experiments of the mX-TMB two-component system were conducted on the samples thus obtained, and the relationship between the amount of TMO8 added and the adsorption ratio of aromatics is shown in FIG.

As is clear from Figure 3, when moisture absorption treatment is not performed, T
It can be seen that even when the amount of MO8 added increases, no shape selectivity is expressed at all.

Comparative Example 2 H-type Y-type zeolite (H-Y) was silanized with TM01 through the same operation as in Example 1.

Here, three types of silanized zeolites with different amounts of TMO8 impregnated were prepared. Competitive adsorption experiments of mX~TMB two-component system were conducted on the sample obtained in this way, and T
FIG. 4 shows the relationship between the amount of MO8 impregnated and the adsorption ratio of each aromatic group.

As is clear from FIG. 4, it can be seen that HY does not exhibit shape selectivity at all even when 7MO8 is attached.

Example 3 and Comparative Example 3 Moisture absorbed Na-Y type (moisture absorption amount -o, ao g-H20
) and Na-Y type materials dried by 500° C. calcination were silanized using the same silanizing agent as in Example 1, and approximately the same amount of 7MO8 (10.25 d/g) was impregnated.

When these two types of silanized zeolite were measured using X-ray photoelectron spectroscopy (XPS) and the thickness of the silica layer formed on the outer surface of the crystal was determined, the results shown in Table 1 below were obtained. Ta.

Table 1 From these results, it can be seen that silanization occurs closer to the outer surface of the crystal by performing the moisture absorption treatment.

[Effects of the Invention] As explained above, according to the method for producing silanized zeolite according to the present invention, the following effects can be obtained.

■By being able to silanize only the outer surface of the zeolite crystal, the pore entrance diameter is narrowed and shape selectivity is developed. Furthermore, by changing the degree of silanization, the pore entrance diameter can be precisely controlled as desired.

Therefore, the zeolite prepared according to the present invention can be applied to reactions and adsorptions that utilize shape selectivity.

(2) Furthermore, according to the present invention, it becomes possible to produce uniformly and in large quantities without reducing the adsorption capacity.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the adsorption amount of each component and the amount of TMO8 impregnated in Example 1, and Figures 2 (a) to (c) are the adsorption ratios of each component with respect to the amount of TMO8 impregnated in Example 2. Figure 3 is a diagram showing the adsorption ratio of each component to the amount of TMO8 impregnated in Comparative Example 1, and Figure 4 is a diagram showing the adsorption ratio of each component to the amount of TMO8 impregnated in Comparative Example 2. be.

Claims (1)

[Claims] 1. A silanized zeolite characterized by absorbing moisture from an alkali or alkaline earth metal ion type zeolite, silanizing it in a liquid phase with an organic silane compound diluted with a hydrophobic solvent, and then calcining it. Manufacturing method. 2. The organic silane compound is SiR_yX_4_-_y [where y is an integer of 1 to 4, X is an alkyl group of C_1 to C_1_0, an aryl group, an arylalkyl group, or hydrogen, and R is an alkoxy group of C_1 to C_1_0, respectively. The method for producing a silanized zeolite according to claim 1, which is a compound represented by the following. 3. The method for producing a silanized zeolite according to claim 1 or 2, wherein the calcination is performed at a temperature of 100 to 600°C.