JP4567129B2 - NU-1 type binderless zeolite molding and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a NU-1 type binderless zeolite molded body and a method for producing a NU-1 type binderless zeolite molded body. The NU-1 type zeolite means “RUT type” zeolite referred to by a code indicating a structure by the International Zeolite Society.
[0002]
[Prior art]
NU-1 type zeolite is a zeolite first discovered in 1977 as an aluminosilicate having small pores of oxygen 6-membered rings, and its structure can be identified by powder X-ray diffraction. A crystalline aluminosilicate composed of silicon and aluminum, which is a metal component that constitutes the zeolite crystal skeleton (hereinafter sometimes referred to as T atom), mainly contains Al ³⁺ cations in the crystal lattice for the purpose of controlling its acidity. Substitution with other metal ions is widely carried out, and generally, NU-1 type zeolite including silicalite having no aluminum structure and crystalline metallosilicate in which aluminum is substituted with other metal ions It is said. As the NU-1 type crystalline metallosilicate, a zeolite containing boron, gallium, iron, titanium and the like in a T atom is known.
[0003]
As a method for synthesizing these NU-1 type zeolites, a so-called hydrothermal synthesis method using an aqueous reaction slurry using a tetramethylammonium salt as a template agent as a raw material has been known.
[0004]
However, in the conventional hydrothermal reaction method, a part of the raw material component is dissolved in water during heating, so that the ratio of the component converted into crystals is inevitably reduced, so the yield is low. In addition, in such a crystallization method in which an alkali component is diluted, a large crystal is likely to grow, and a foreign metal component (M) other than silicon (Si) is easily excluded outside the crystal lattice. The atomic ratio of Si / M (M represents a T atom other than silicon) in the slurry does not necessarily match the atomic ratio of Si / M in the synthesized NU-1 type zeolite. Furthermore, industrially, in order to heat the aqueous slurry, a closed container having a relatively large volume with respect to the weight of the generated crystals is required, a large amount of expensive template agent needs to be used, and a large amount of waste liquid. Generation of zeolite, filtration of the zeolite powder, and a complicated firing process.
[0005]
Further, in the case of producing a conventional zeolite molded body, since the moldability of zeolite alone is poor, it has been necessary to first synthesize zeolite powder by a hydrothermal synthesis method and then mold it using an inorganic binder. In this method, it is necessary to select a binder that does not adversely affect the intended use, and in order to obtain sufficient strength, a large amount of an inorganic binder is required. In addition, there is a problem in that the zeolite embedded in the binder cannot be effectively used, and a method for producing a supported zeolite molded body using an inorganic molded body has also been proposed. For example, in JP-A-11-165074, an aqueous gel comprising tetraethylorthosilicate, tetraethylorthotitanate and tetrapropylammonium hydroxide is supported on a silica carrier and then treated with steam under pressure to perform MFI type crystalline titano. Silicate is crystallized on the support. In this method, since it is necessary to use a low-concentration aqueous gel having sufficient fluidity to be supported on the carrier, the amount supported on the carrier is extremely low. That is, the supported zeolite molded body obtained by this method has a problem that the zeolite content is extremely low.
[0006]
In view of this, several methods for producing a molded zeolite containing substantially no binder have been proposed. For example, Japanese Patent Application Laid-Open Nos. 59-162952 (TSZ type aluminosilicate) and Japanese Patent Application Laid-Open No. 61-72620 (MOR type aluminosilicate). ) And Japanese Patent Application Laid-Open No. 62-138320 (FAU type aluminosilicate) are known to be limited to several types of crystalline binderless aluminosilicate moldings. However, no binderless NU-1 type aluminosilicate molded body has been known.
[0007]
In addition, these methods use a zeolite powder synthesized beforehand as a secondary raw material, and convert the binder into zeolite by reacting it with an inorganic solution such as clay mineral or silica alumina sol. Therefore, substantially twice hydrothermal synthesis is required. For this reason, there are problems in that the process becomes longer and the amount of waste liquid increases.
[0008]
Furthermore, a method for synthesizing a binderless silicalite molded body in which the metal component constituting the crystal skeleton is substantially composed only of silicon or a binderless crystalline metallosilicate molded body composed of T atoms other than aluminum is known. It wasn't.
[0009]
As mentioned above, the NU-1 type binderless zeolite molding which does not contain a binder substantially, and its simple and efficient manufacturing method were not known.
[0010]
[Problems to be solved by the invention]
Then, the objective of this invention is made | formed in view of the above problem, and it is providing the NU-1 type binderless zeolite molded object which consists only of a zeolite crystal, without containing an inorganic binder. is there.
[0011]
Another object of the present invention is to provide a simple and efficient method for producing a NU-1 type zeolite molded body that does not use a binder.
[0012]
[Means for Solving the Problems]
As a result of intensive studies on the NU-1 type binderless zeolite molding, the present inventors, for example, after supporting a tetramethylammonium component, an alkali metal component, and other metal components on a silica molding together with specific conditions NU-1 type binderless zeolite which essentially contains no binder and crystallizes the entire amount of silica while maintaining the shape of the silica molding by the method of contacting with saturated steam at the same time. The present inventors have found that a molded body can be easily produced with high yield and have completed the present invention.
[0013]
That is, the present invention relates to a binderless zeolite molding, wherein the zeolite has a NU-1 type crystal structure.
[0014]
The binderless zeolite molded body, for example, the specific surface area determined from nitrogen adsorption measurements by BET method, which is binderless zeolite molded body is 20m ² / g~200m ² / g.
[0015]
Another invention of the present invention is represented by the following formula (1):
Si ₁ (TMA) _x M ¹ _y M ² _z (1)
(In the formula, TMA is tetramethylammonium, M ¹ is an alkali metal, M ² is a metal element incorporated in the metallosilicate crystal skeleton, x is 0.01 to 1, y is 0.0001 to 1, and z is 0. Represents a range of ~ 0.3)
It is related with the manufacturing method of the binderless zeolite molded object characterized by making a zeolite precursor represented by 80-260 degreeC saturated steam contact.
[0016]
The zeolite precursor is preferably a zeolite precursor obtained by supporting a raw material containing a tetramethylammonium component, an alkali metal component, and a metal component incorporated in a metallosilicate crystal skeleton on a silica molded body. is there.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Details of the present invention will be described below.
[0018]
The zeolite precursor used in the method for producing a binderless zeolite molding of the present invention is represented by the following formula (1):
Si ₁ (TMA) _x M ¹ _y M ² _z (1)
(In the formula, TMA is tetramethylammonium, M ¹ is an alkali metal, M ² is a metal element incorporated in the metallosilicate crystal skeleton, x is 0.01 to 1, y is 0.0001 to 1, and z is 0. Represents a range of ~ 0.3)
If it is a composition represented by, it will not specifically limit. In the formula (1), M ¹ represents an alkali metal such as lithium, sodium, or potassium, and M ² represents a metal element incorporated in the metallosilicate crystal skeleton, such as boron, aluminum, titanium, iron, zinc, gallium, and indium. Represents at least one element selected from the group consisting of Furthermore, in the formula (1), x is preferably in the range of 0.02-1, y is in the range of 0.0001-1 and z is in the range of 0-0.25, and in the formula (1), x Is more preferably 0.04 to 0.8, y is 0.0002 to 0.5, and z is 0 to 0.2.
[0019]
The method for preparing the zeolite precursor is not particularly limited, but a raw material containing a tetramethylammonium component, an alkali metal component, and at least one metal component incorporated in a metallosilicate crystal skeleton supported as desired, A method of supporting on a silica molded body is preferable.
[0020]
When the tetraalkylammonium component and the alkali metal component are supported on the silica molded body, a binderless NU-1 type silicalite molded body consisting of silicon-only T atoms can be produced. In addition to boron, aluminum, titanium, chromium, iron, cobalt, nickel, copper, zinc, gallium, and at least one metal component selected from the group consisting of indium, it was incorporated as a T atom. A NU-1 binderless crystalline metallosilicate molded product can be produced.
[0021]
The silica molded body is not particularly limited, and a commercially available product can be used. Silica molded body used suitably is relatively large molded specific surface area, specific surface area determined from nitrogen adsorption measurements by conventional BET method, for example, 5m ² / g~1000m ² / g, preferably 20 m ² / g to Those in the range of 800 m ² / g are used. This is because if the specific surface area is too small, a long time is required for crystallization, and the degree of crystallization may deteriorate.
[0022]
Further the silica molded body, for example, the pore diameter determined by mercury intrusion porosimetry has pores of more than 4 nm, surface area and pore volume due to pores each ^{5m 2 / g~1000m 2 / g,} 0 was .10ml / g~1.5ml / g, and preferably from 20m ² / g~800m ² /g,0.15ml/g~1.3ml/g.
[0023]
Examples of the tetramethylammonium component include tetramethylammonium halides and hydroxides, and tetramethylammonium hydroxide is preferably used. By using tetramethylammonium hydroxide, NU-1 type zeolite can be synthesized efficiently.
[0024]
Examples of the alkali metal component include lithium, sodium, potassium, and the like, and hydroxides, halides, silica carriers and / or alkali metal components in metal salt compounds can also be used.
[0025]
In the case of synthesizing a NU-1 type binderless crystalline metallosilicate molded body, a metal salt to be a T atom is supported on a silica carrier together with the tetramethylammonium component and the alkali metal component. Examples of these metal salts include boron, aluminum, titanium, chromium, iron, cobalt, nickel, copper, zinc, gallium, indium, and other nitrates, sulfates, halides, oxoacid salts, hydroxides, and the like. It is preferable to use these in the form of an aqueous solution. The metal salt is preferable in that a high crystallinity can be obtained when a metal salt of at least one metal selected from the group consisting of boron, aluminum, iron and gallium is used. These metal components are converted into a binderless metallosilicate by being incorporated into the zeolite framework during crystallization.
[0026]
A method for supporting a raw material material containing a tetramethylammonium component, an alkali metal component, and one or more metal components incorporated in a metallosilicate crystal skeleton supported as desired on the silica molding is particularly limited. However, since it is desirable to uniformly support the raw material in the silica molded body, it is usually performed by impregnating with an aqueous solution and then drying. As an example, a predetermined amount of each component is made into a uniform aqueous solution, and is prepared and impregnated so as to have an aqueous solution amount that matches the water absorption amount of the silica molded body. At this time, each component may be supported at the same time, or each component or a uniform mixed solution may be divided and supported in several times. Will not be affected.
[0027]
The drying temperature after impregnating the aqueous solution is not particularly limited, but is preferably 20 ° C. to 150 ° C., more preferably 50 ° C. to 120 ° C., in that the decomposition of the tetramethylammonium salt is small and efficient and the water content is suppressed. Performed at ° C. The water content of the precursor is preferably 30% or less, and more preferably in the range of 20% to 0.1% in that the supported component does not elute during crystallization and the yield is good.
[0028]
Further, the drying method is not particularly limited, and the drying can be carried out under any conditions of reduced pressure and normal pressure. Since it is easy to dry under an air stream at normal pressure, it is preferable.
[0029]
The production method of the present invention is characterized in that the zeolite precursor is brought into contact with saturated steam.
[0030]
The temperature of the saturated water vapor is not particularly limited, and it is 80 to 80 in that a NU-1 type binderless zeolite molded body having a high crystallization rate, less decomposition of the contained tetramethylammonium component and high crystallinity can be obtained. The range of 260 ° C is preferable, and 100 ° C to 240 ° C is more preferable.
[0031]
The contact time with the saturated water vapor is not particularly limited, and is usually in the range of 5 to 300 hours, preferably 12 to 200 hours. If the crystallization time is too short, the crystallinity is lowered, and if it is too long, a mixed crystal with another mineral may be formed.
[0032]
The method and apparatus for heating the zeolite precursor in contact with saturated steam is not particularly limited. For example, it can be carried out by placing the precursor in the hollow of the pressure vessel and enclosing water corresponding to the saturated water vapor amount determined by the reaction temperature and the volume of the vessel at the bottom of the vessel, followed by heating in a thermostatic chamber, The embodiment is not limited to this. The precursor may be placed in a container and a sealed container with water on the outside may be used. Alternatively, the precursor may be continuously synthesized by a fixed bed reactor or a moving bed reactor in which the precursor is brought into contact with saturated steam. You can also
[0033]
By using the production method of the present invention, the zeolite precursor can be crystallized by contacting with saturated steam without being dispersed in water and subjected to hydrothermal reaction. The NU-1 type zeolite having T atoms as the supported metal components can be converted. As a result, since the entire amount of the silica molded body as a raw material is converted into zeolite while maintaining its shape, the produced zeolite essentially contains no binder, and a NU-1 type binderless zeolite molded body can be easily produced. It is guessed.
[0034]
Since no binder is used in the production method of the present invention, the NU-1 type zeolite molded body synthesized by the production method of the present invention has a very high crystallinity with a zeolite content of almost 100%. By selecting an appropriate composition ratio of precursor, crystallization temperature and crystallization time from the above conditions, the crystallinity of the molded product can be controlled, for example, 95% or more, preferably 98% or more. . The crushing strength can be controlled by the degree of crystallinity.
[0035]
Further, in the production method of the present invention, a silica molded body is molded into an arbitrary shape such as a spherical shape, a cylinder shape, or a ring shape by a conventional method, and then converted into a zeolite by the method according to the present invention, whereby a spherical shape, a cylinder shape, a ring shape is obtained. A binderless zeolite molded body having an arbitrary shape such as a mold can be produced. Since the silica support itself as a raw material is converted into zeolite as it is, a binderless zeolite molded body maintaining the shape of the silica molded body can be obtained.
[0036]
Moreover, in the manufacturing method of this invention, not only the external appearance of a raw material silica molded object is hold | maintained but crushing strength, macropore distribution, etc. are reflected. For this reason, the physical property of a binderless zeolite molding can be easily controlled by controlling the physical property of the silica molding used for a raw material by a conventional method.
[0037]
Moreover, the binderless zeolite molding of the present invention is
(1) the zeolite has a RUT type crystal structure, and (2) the composition ratio (atomic ratio) between silicon and the metal constituting the zeolite crystal structure is 0 to 0.00. It is the range of 3.
[0038]
The zeolite in the molded body of the present invention has a RUT type crystal structure. This can be confirmed by comparing the powder X-ray diffraction spectrum of the obtained zeolite with, for example, the powder X-ray diffraction spectrum shown in the literature (Zeolites 18: 361 (1997)).
[0039]
The structure of RUT-type zeolite forms a zeolite crystal skeleton by three-dimensionally bonding TO ₄ tetrahedrons in which four oxygen atoms are coordinated at the apex with T atoms as the center. For this reason, silicalite whose T atom is composed only of silicon is electrically neutral and therefore does not exhibit solid acidity. It is well known that when Si ⁴⁺ is replaced by another valent metal, cations such as protons exist in the crystal to electrically neutralize the TO ₄ anion, and thereby solid acidity is expressed. ing. These cations can be easily ion-exchanged by ordinary operations. Further, the amount of solid acidic acid and the acid strength that are expressed can be controlled by the amount and type of the element introduced as T atom. The solid acidity can be evaluated by a temperature desorption (TPD) method of ammonia.
[0040]
In the molded body of the present invention, the composition ratio (atomic ratio) of the metal components constituting the zeolite crystal structure in the molded body is in the range of 0 to 0.3, preferably 0.0005 to 0.00. It is the range of 2.
[0041]
The molded body of the present invention are, for example, the specific surface area determined from nitrogen adsorption measurements by the BET method is 20m ² / g~200m ² / g, preferably in the range of 30m ² / g~180m ² / g.
[0042]
The molded body of the present invention has, for example, secondary pores having a pore diameter of 4 nm or more determined by mercury porosimetry, and the surface area and pore volume of each pore are 2 m ² / g to 150 m ² / g, a 0.10ml / g~1.5ml / g, preferably in the range of 3m ² / g~100m ² /g,0.13ml/g~1.3ml/g.
[0043]
The molded body of the present invention can be easily and efficiently manufactured by, for example, the above-described method for manufacturing a binderless zeolite molded body.
[0044]
Examples of the shape of the molded body of the present invention include a spherical shape, a cylinder shape, and a ring shape, but are not particularly limited.
[0045]
The molded body of the present invention can be used as an adsorbent, a catalyst for a chemical reaction, or a catalyst carrier in various chemical processes because the shape, size, macropore distribution, etc. can be easily controlled. It is suitably used for an alkylation reaction catalyst, an isomerization reaction catalyst, a transesterification reaction catalyst, a cracking reaction catalyst, a Beckmann rearrangement reaction catalyst, a hydration reaction catalyst, an alcohol addition reaction catalyst, a liquid ammonium alkanolamine synthesis catalyst, and the like.
[0046]
【Example】
The present invention is specifically described by the following examples, but the present invention is not limited to these examples.
[0047]
Example 1
2.2 ml of 4 mol / l sodium hydroxide aqueous solution and 12.5 g of 26% by weight aqueous tetramethylammonium hydroxide (abbreviated as TMA) were mixed, and the total volume was made up to 15 ml with distilled water. 10.7 g of silica beads dried at 120 ° C. for one day and night (“CARTIACT Q-10” manufactured by Fuji Silysia Chemical Co., Ltd., 10-20 mesh) are impregnated with 15 ml of the aqueous solution for 1 hour, and TMA and sodium are added onto the silica beads. Ingredients were loaded. The composition ratio is Si ₁ TMA _0.2 Na _0.05 .
[0048]
This was transferred onto an evaporating dish, dried on a 90 ° C. hot water bath, and then dried in an 80 ° C. oven under a nitrogen stream for 3 hours. The obtained precursor was put in a cage made of a stainless steel net and placed in the hollow of a Teflon crucible having a volume of 100 ml. 1 g of distilled water was added to the bottom of the crucible and heated at 170 ° C. for 144 hours. The product taken out after the crucible was cooled to room temperature was 10 to 20 mesh size beads while retaining the appearance of the silica beads used as a raw material. This is product A.
[0049]
As a result of powder X-ray diffraction measurement after pulverizing the product A, it was NU-1 type silicalite as shown in FIG.
[0050]
Example 2 in which the specific surface area calculated by the BET three-point method of nitrogen at 77 K (P / P0 = 0.10, 0.20, 0.30) was 137 m ² / g
Sodium aluminate 0.27 g was dissolved in 26 wt% TMA aqueous solution 9.90 g, and the total volume was made up to 12 ml with distilled water. 8.48 g of silica beads (Fuji Silysia Chemical “Caractect Q-10”, 10-20 mesh) dried at 120 ° C. for one day are impregnated with 12 ml of the aqueous solution for 1 hour, and sodium aluminate is placed on the silica beads. And TMA were supported. The composition ratio is Si ₁ TMA _0.2 Na _0.026 Al _0.02 .
[0051]
This was transferred onto an evaporating dish, dried on a 90 ° C. hot water bath, and then dried in an 80 ° C. oven under a nitrogen stream for 3 hours. The obtained precursor was crystallized in the same manner as in Example 1. The product taken out was beads having a size of 10 to 20 mesh while maintaining the appearance of the silica beads used as a raw material. This is product B.
[0052]
As a result of powder X-ray diffraction measurement after pulverizing the product B, a diffraction pattern essentially the same as that in FIG. 1 was given, and it was a NU-1 type aluminosilicate.
[0053]
The specific surface area calculated by the BET three-point method of nitrogen at 77 K (P / P0 = 0.10, 0.20, 0.30) was 92 m ² / g.
[0054]
In addition, as a result of ammonia TPD measurement after ion exchange to proton type, a desorption peak due to a strong acid point derived from [AlO ₂ ] ⁻ in the lattice was observed at 265 ° C., so the supported aluminum atom was taken into the zeolite lattice. It turns out that it is a T atom.
[0055]
【The invention's effect】
Since the NU-1 type binderless zeolite molding of the present invention contains essentially no binder, the zeolite content in the molding is extremely high, and the zeolite is not buried in the inorganic binder. For this reason, there is a feature that zeolite can be used efficiently and there is no adverse effect caused by impurities such as an inorganic binder.
[0056]
According to the method of the present invention, NU-1 type binderless zeolite molding can be easily produced because crystallization is carried out by bringing the molded precursor and saturated water vapor into contact.
[0057]
In addition, according to the method of the present invention, since the raw material component does not elute in water, the metal component is efficiently taken into the crystal lattice, and as a result, the NU-1 type having a composition almost identical to the raw material charged composition. A crystalline metallosilicate can be produced with good yield.
[0058]
Further, according to the method of the present invention, the produced NU-1 type binderless zeolite molded body reflects the properties of the raw material silica molded body as it is, and therefore it is easy to control physical properties such as the secondary pore structure. In addition, since the amount of expensive tetraalkylammonium used can be reduced, and almost no waste liquid is generated, there is no need for recovery and waste liquid treatment, which is economical.
[Brief description of the drawings]
1 shows a CuKα X-ray diffractogram of product A synthesized in Example 1. FIG.

Claims (2)

Following formula (1)
Si ₁ (TMA) _x M ¹ _y M ² _z (1)
(In the formula, TMA is tetramethylammonium, M ¹ is an alkali metal, M ² is a metal element incorporated in the metallosilicate crystal skeleton, x is 0.01 to 1, y is 0.0001 to 1, and z is 0. A method for producing a molded article of NU-1 type binderless zeolite, wherein the zeolite precursor represented by the formula (1) is brought into contact with saturated steam. The zeolite precursor carries a raw material material containing a tetramethylammonium component, an alkali metal component, and, optionally, a metal element component represented by M ² in the formula (1) on a silica molded body. the process according to claim 1, wherein a zeolite precursor comprising.

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