JP5115947B2 - Novel layered silicate PLS-3 by solid phase reaction method, method for producing the same, and method for producing FER type zeolite using the same as a precursor - Google Patents

Description

  The present invention relates to a method for synthesizing a novel crystalline layered silicate PLS-3, a high silica zeolite CDS-3 synthesized using it as a precursor, and a method for producing the same. The present invention provides a high-silica zeolite excellent in heat resistance that can be used, for example, as a separating agent, an adsorbent, a shape-selective solid catalyst, an ion exchange agent, a chromatography filler, a chemical reaction field, and a building material. A novel crystalline layered silicate, which is a precursor compound for the production, is rapidly produced by a phase transition reaction from a solid phase to a solid phase using an existing crystalline layered silicate, and is used as a precursor. The present invention provides a synthesis method and a product thereof that make it possible to synthesize high silica zeolite.

  Zeolite has micropores (3-20Å) regularly arranged at the atomic level, and the framework element is aluminosilicate type consisting of Si, Al, O, high silica (Pure Silica) consisting only of Si, O. ) Mainly can be classified into types. Zeolite has a chemical / physical adsorption action that is either shape-selective or due to its skeletal structure, so it has functions as, for example, molecular sieves, separated adsorbents, ion exchangers, and catalytic reactions. . More than 160 types of structures are known as natural and synthetic zeolites, and by combining them with the composition of skeletal elements, petrochemistry can be used as a porous material that combines chemical properties, structural stability, and heat resistance according to the purpose. Used in a wide range of industrial fields.

  Each zeolite can be distinguished experimentally because it is distinguished by a geometric framework structure that forms regular pores and gives a unique X-ray diffraction pattern. That is, the skeletal structure (crystal structure) defines the shape and size of the pores of the zeolite. The adsorption characteristics, mechanical strength, and solid acid performance of each zeolite are determined in part by the shape and size of the pores and the composition of the skeleton. Thus, when considering a particular application, the usefulness of a particular zeolite depends at least in part on its crystal structure and composition.

  A zeolite with a high silica composition is superior to a zeolite with a low silica composition in two points of heat resistance and hydrophobicity, and generally has sufficient mechanical strength. These properties are important when, for example, zeolite is used as a separating agent or a catalyst. In the initial stage of zeolite synthesis research, only a product with a low silica / alumina ratio was obtained, but by adding an organic structure directing agent (OSDA) to the starting gel consisting of a silica source, It has become possible to synthesize zeolite having a composition with a very high silica / alumina ratio (Non-patent Document 1).

  Zeolite is generally hydrothermally synthesized, that is, a large amount of water and a silica source, an aluminum source, an alkali metal, and amines such as OSDA are blended to have a desired chemical composition, and they are placed in a pressure vessel such as an autoclave. Manufactured under self-pressure by containment heating. Here, OSDA functions as a templating agent for forming pores of the generated zeolite, and amine molecules are mainly used. In recent years, in the field of catalysts and materials, there is an increasing demand for a high-silica zeolite having a larger pore diameter, and many studies have been made, but it is difficult to put it to practical use because the manufacturing cost and the design and synthesis of OSDA are not easy. Thus, the types of high silica zeolite actually used are very few, and the pore diameter is limited to a silicon 12-membered ring or less.

  On the other hand, a technique for changing the structure from a layered silicate to a zeolite or a microporous structure using a reaction similar to a phase transition from a solid phase to a solid phase without using a large amount of water has been reported. Although there are few research examples, MFI type (silicalite-1) and MEL type zeolite (silicalite-2) have been reported as zeolites having a known structure that can be synthesized (Patent Documents 1 and 2, Non-Patent Documents 2 to 2). 6).

  According to these, in the solid-phase reaction, the product is said to be obtained simply by adding layered silicate powder crystals, organic amine molecules and water to the raw material and heating using an autoclave. In addition, the solid phase reaction is characterized in that the reaction time is several hours to 24 hours, which is a rapid synthesis method compared to the hydrothermal synthesis method. In addition, since solid phase reaction can reduce necessary raw materials to a minimum as compared with hydrothermal synthesis method, cost reduction of the synthesis process is expected. However, since many of the products have no similarity or commonality between the structure of the product and the layered silicate starting material, it is pointed out that the mechanism of phase transition is not clear. Yes.

  In recent years, a new method has been reported in which a layered structure of crystalline layered silicate is crosslinked by a dehydration polycondensation reaction to obtain a high silica zeolite. For example, crystalline layered silicate PLS-1 has recently been found as a precursor of CDO-type high silica zeolite, and CDO-type high silica zeolite can be obtained simply by calcining this PLS-1. Conventionally, the production method of PLS-1 is hardly contained in PLS-1, which is the final product, in addition to silica and TMAOH, but requires an alkali source and 1,4-dioxane for crystallization, and is synthesized. The time was also required for about 10 days (Patent Documents 3 to 6, Non-Patent Document 7).

  The novel crystalline layered silicate obtained in the present invention corresponds to a precursor of FER type high silica zeolite, and, just like PLS-1, the layers are crosslinked by dehydration polycondensation reaction just by firing, As a result of newly forming fine pores there, the structure changes to FER type high silica zeolite. FER type zeolite is regarded as an important zeolite in industrial use, and a great number of application examples have been reported (Patent Documents 7 to 15).

  In addition, various studies have been conducted on the synthesis method of FER type zeolite itself (Patent Documents 16 to 21, Non-Patent Documents 8 to 10). Further, a crystalline layered silicate PREFER that can be converted into FER type zeolite has been reported by Schreyeck et al. (Non-patent Documents 11 and 12). However, this method requires not only the expensive amine molecule 4-amino-2,2,6,6-tetramethylpiperidine but also extremely toxic hydrogen fluoride for the synthesis of PREFER, and the synthesis time is also long. Since it takes 15 days, it is not suitable for industrial use.

  In the zeolite synthesis by the hydrothermal synthesis method so far, many aluminosilicate types including Al element in the skeleton, including the FER type, have been reported. In the case of high silica zeolite, the synthesis time generally takes about 5-14 days, and it is not uncommon for it to take a longer synthesis time. In the high silica FER type zeolite, a synthesis example that takes 8 weeks has been reported (Non-patent Document 13).

  In addition, conventional hydrothermal synthesis methods sometimes require a large amount of additives, organic solvents, water and the like as synthesis conditions, although they are not included in the product. In the synthesis of high-silica zeolite aimed at industrial use, development of synthetic methods that reduce the consumption of raw materials and thermal energy as much as possible and consider the environment has become a major issue. The same applies to the synthesis of FER type zeolite.

JP 2003-073115 A JP-A-8-319112 JP 2005-041763 A JP 2005-194113 A JP 2004-339044 A JP 2004-175661 A JP-A-5-49935 Japanese Patent Laid-Open No. 6-198189 JP-A-6-262039 JP-A-7-185326 JP-A-8-141368 Japanese Patent Laid-Open No. 11-216359 JP 2000-237561 A JP 2001-286752 A JP 2000-237561 A JP-A-8-188414 Japanese Patent Laid-Open No. 10-15401 European Patent 55,529 B (1985) US Pat. No. 4,578,259 (1986) European Patent 103,981 A (1984) US Patent 4,016,245 (1977) R. M. Barrer, Hydrothermal Chemistry of Zeolites, New York: Academic Press, Inc. pp. 157-170 (1982) M. Salou, Y. Kiyozumi, F. Mizukami, P. Nair, K. Maeda and S. Niwa J. Mater. Chem., 8 (9), 2125-2132 (1998) F. Kooli, Y. Kiyozumi and F. Mizukami, New J. Chem., 25, 1613-1620 (2001) F. Kooli, Y. Kiyozumi, V. Rives, and F. Mizukami, Langmuir, 18, 4103-4110 (2002) F. Kooli, F. Mizukami, Y. Kiyozumia and Y. Akiyama, J. Mater. Chem., 11, 1946-1950 (2001) F. Kooli, J. Mater. Chem., 12, 1374-1380 (2002) T. Ikeda Y. Akiyama, Y. Oumi, A. Kawai, F. Mizukami, Angew. Chem. Int. Ed., 43, 4892-4895 (2004) Barrer, R.M. and Marshall, D. J., J. Chem. Soc., 2296-2305 (1964) Morris, R. E., Weigel, S. J., Henson, N. J., Bull, L. M., Janicke, M. T., Chmelka, B. F. and Cheetham, A. K. J. Am. Chem. Soc., 116, 11849-11855 (1994) Gies, H. and Gunawardane, R. P., Zeolites, 7, 442-445 (1987) L. Schreyeck, P. Caullet, J. C. Mougenel, J. L. Guth, B. Marler, Microporous Mater., 6, 259 (1996) L. Schreyeck, P. Caullet, J. C. Mougenel, J. L. Guth, B. Marler, Stud. Surf. Sci. Catal., 105, 1949 (1997) Gies, H. and Gunawardane, R. P. Zeolites, 7, 442-445 (1987)

  Under such circumstances, the present inventors have expanded the conventional solid-phase reaction technology in view of the above-described conventional technology, and studied various combinations of crystalline layered silicates and amine molecules for synthesis. In the process of analysis and analysis, it is possible to synthesize FER type zeolite precursor crystalline layered silicate more easily and in a short time by solid phase reaction, and by heating it, high silica FER type zeolite can be synthesized. The present invention has been found, and the present invention has been completed.

The present invention for solving the above-described problems comprises the following technical means.
(1) the crystalline layered silicate kanemite (Kanemite) the acid-treated H-type kanemite (H-Kanemite), as organic crystallization modifier, a tetraethylammonium hydroxide (TEAOH) aqueous solution, the molar ratio TEAOH / Si = 0.10-0.35, H ₂ O / Si = 2.26-11.36, and the raw material is subjected to a solid phase reaction in a water vapor atmosphere in a pressure vessel (autoclave). A method for producing a crystalline layered silicate PLS-3, comprising synthesizing a crystalline layered silicate PLS-3 having a relationship between a diffraction peak position shown in Table 2 and a relative intensity .
(2) An aluminate crystal is added to the raw material as an Al source, and a solid phase reaction is performed in a water vapor atmosphere in a pressure vessel (autoclave) to synthesize an Al-containing crystalline layered silicate. 1) The method for producing the crystalline layered silicate PLS-3 according to the above .
(3) H-kanemite obtained by acid-treating crystalline layered silicate kanemite , tetraethylammonium hydroxide (TEAOH) aqueous solution as the organic crystallization modifier, and a molar ratio of TEAOH / Si = 0.10-0 .35, H ₂ O / Si = 2.26-11.36, and in a pressure vessel (autoclave) at a temperature range of 160-180 ° C. for heating conditions at 24-72 hours. The method for producing the crystalline layered silicate PLS-3 according to (1), wherein a solid phase reaction is performed in a water vapor atmosphere.
(4) The method for producing crystalline layered silicate PLS-3 according to (2), wherein sodium aluminate crystals are added to the raw material as the Al source in a Si / Al ratio of 25-50.
(5) (1) to (4) a crystalline layered silicate PLS-3 was synthesized by the method described in any one of, having a relationship of diffraction peak positions and relative intensities shown in Table 2 Crystalline layered silicate PLS-3 characterized by
(6) Ke consisting skeletal structure of layered, characterized in that it consists covalent bond Si-O having a Lee-containing 5-membered ring, wherein the (5) crystalline layered silicate PLS-3 description.
(7) the (5) or a crystalline layered silicate PLS-3 according to (6), the manufacturing method of the full Erieraito (FER) type zeolite you characterized by causing dehydration polycondensation.
(8) the crystalline layered silicate PLS-3, was heated at 250 ° C. or higher at or reduced under vacuum atmosphere, dehydration polycondensation to the (7) The method of producing full Erieraito (FER) type zeolite according .

Next, the present invention will be described in more detail.
The present invention will be described below with reference to the drawings. First, the crystalline layered silicate kanemite used in the present invention will be described. The chemical composition in the unit cell of Kanemite is defined by Si ₈ O ₁₆ (OH) _4. [Na (H ₂ O) ₃ ] ₈ and has a crystal structure represented by the crystal structure model of FIG. ing. The Si—O tetrahedral coordination repeating unit has a silicate basic structure, and a structure in which Na ions and water molecules are regularly sandwiched between layers (reference: S. Vortmann, J. Rius, B. Marler and H. Gies, European Journal of Mineralogy, 11, 125-134 (1999)).

  The kanemite used in the method of the present invention may be synthesized by any method, but it is a necessary condition that it has the above chemical composition and the crystal structure defined in the literature. In the present invention, kanemite is synthesized by commercially available crystalline layered sodium silicate, specifically, for example, as an example, 30 g of SKS-6 (manufactured by Tokuyama Siltech Co., Ltd.) in 500 ml of distilled water at room temperature for 3 hours. After soaking, only the precipitate separated by centrifugation is taken out and dried by a dryer at 50 ° C. for 12 hours.

  The organic amine used in the solid phase reaction is considered to play a role as a structure-directing agent. As this organic amine, a layered silicate is used as a starting source, so that it can be accessed between layers and can be expanded, and any organic amine can be used as a template for forming a silicate skeleton structure. Anything can be used. Examples of the organic amine include quaternary alkyl ammonium salts such as tetramethyl ammonium salt, tetraethyl ammonium salt, tetrapropyl ammonium salt, and tetrabutyl ammonium salt. The organic crystallization regulator preferably used in the present invention is a tetraethylammonium salt. Next, production of each target product in the present invention will be specifically described.

New crystalline layered silicate:
The acid treatment of kanemite is performed, for example, simply by stirring the kanemite crystals in an aqueous hydrochloric acid solution. The acid-treated H-type kanemite has a chemical composition of Si ₈ O ₁₆ (OH) ₄ and has a structure in which sodium ions and water molecules are removed from the interlayer. This powder X-ray diffraction pattern gives a diffraction line position and diffraction intensity as shown in the H-kanemite powder X-ray diffraction pattern of FIG. The acid treatment of kanemite is preferably a strong acid such as hydrochloric acid or nitric acid, but is not limited to this as long as it has a strong dehydrating action and does not remain in kanemite after acid treatment. .

  Next, an organic crystallization modifier is added to the H-type kanemite, and a solid phase reaction is performed in a water vapor atmosphere in a pressure vessel (autoclave). For example, as an example, 0.5 g of this H-type kanemite powder and 20 wt% concentration of tetraethylammonium (TEAOH) aqueous solution (SIGMA-ALDRICH Corp. manufactured by SIGMA-ALDRICH Japan K.K.) 0.799 g (TEAOH / Si = 0) 15) is added to a 23 ml autoclave (manufactured by Parr) having a PEFE Teflon (registered trademark) inner cylinder container. FIG. 3 schematically shows the state in the autoclave in the solid phase reaction.

Since the TEAOH reagent used is an aqueous solution, 0.639 g of H ₂ O (concentrated in terms of molar ratio: H ₂ O / Si = 4.87) is included in association with TEAOH from the concentration. Become. The autoclave thus prepared is heated in an oven at 170 ° C. for 24 hours to cause a solid phase reaction in a steam atmosphere. After completion of the heating, the product is sufficiently cooled, and the product in the autoclave is separated by suction filtration and dried at 60 ° C. to obtain a powdery final product. The yield is almost 100% with respect to the silica source, and the product color is white. The powder X-ray diffraction pattern of this product has a relationship between the diffraction peak position shown in Table 3 and the relative intensity, and FIG. 4 (X-ray diffraction pattern of the product obtained by solid phase reaction (Run No. 2)). ).

The proof that the compound produced in this way is layered was performed by structural analysis from ²⁹ Si DDMAS NMR and powder XRD. The following analysis data was obtained by analyzing with the sample of Example 1 described later. ²⁹ Si DDDMA NMR spectrum showing a local structure composed of Si and surrounding O is shown in FIG. 5 (new layered silicate PLS-3 (Run No. 2) and high silica FER type obtained by firing it. ²⁹ Si DDDMA NMR spectrum of zeolite CDS-3). In the spectrum, peaks (−102.4 ppm) attributed to the Q3 structure and peaks (−108.6, −112.1, −116.4 ppm) attributed to the Q4 structure were observed. This means that in the Q3 structure, there are three Si-Os around one Si, and in the Q4 structure, there are four Si-Os.

Since Si is tetrafunctional, the remaining one functional group of the Q3 structure is not Si—O. In this case, O is O ^- or OH. Normally, zeolite is a completely closed Si—O network, so all have a Q4 structure. The inclusion of the Q3 structure indicates that the network is partially interrupted and means that the silicate has a layered structure. Further, from the crystal structure analysis based on the powder XRD data, a crystal structure similar to the conceptual structure shown in the schematic diagram showing the crystal structure of the novel layered silicate PLS-3 in FIG. It became clear that it was a layered structure consisting of Further, from the indexing analysis, it was found that the lattice constants were a = 13.994９９, b = 7.417Å, and c = 23.337Å. This novel crystalline layered silicate compound is referred to as PLS-3.

In addition, this ^PLS-3, shows a spectrum by 13 C CPMAS and ¹³ C DDMAS NMR measurement in FIG. A peak derived from the ethyl group of the TEAOH molecule is observed at 51.4 ppm, and a peak derived from the methyl group is observed at 8.7 ppm. From this, it became clear that TEAOH molecules were included in the crystal of the product PLS-3.

  Furthermore, when TG-DTA measurement was performed on this PLS-3, as shown in the TG-DTA curve (Run No. 2) of the novel layered silicate PLS-3 in FIG. A moderate weight loss of about 11 wt% is observed due to water desorption. Thereafter, an exothermic peak was observed over a temperature range of 250 to 370 ° C., and a weight loss of about 11 wt% was observed. Therefore, it can be understood that TEAOH molecules are burned and desorbed in this temperature range.

  Further, SEM observation of this PLS-3 was conducted. As shown in the SEM image of PLS-3 in FIG. 9 and high silica zeolite CDS-3 obtained by firing the PLS-3, It was clarified that they were very small crystals and aggregated to form higher-order aggregates of several microns. Further, when the synthesis conditions were studied and a synthesis condition map of TEAOH / Si-heating time at a heating temperature of 170 ° C. was created, the results shown in FIG. 10 were obtained as the PLS-3 generation region. It was.

Al-containing new crystalline layered silicate:
An Al-containing crystalline layered silicate synthesized by introducing an Al source (referred to as Al-PLS-3) will be described. To the raw material of PLS-3 described above, sodium aluminate (manufactured by Wako Pure Chemical Industries, Ltd.) was added so that Si / Al = 25-50. As a result, a powder X-ray diffraction pattern similar to that of PLS-3 was obtained (see Examples).

The proof that Al element was introduced into the skeleton of Al-PLS-3 can be explained from the ²⁷ Al-MAS NMR spectrum of Al-CDS-3 shown in FIG. An Al tetracoordinate structure at 52.4 ppm, that is, a signal attributed to AlO ₄ and a signal attributed to a hexacoordinate structure (AlO ₆ ) at 6.6 ppm were observed. A signal due to the tetracoordinate structure was observed, which means that a part of the Si site in the layered skeleton is replaced with Al. In addition, there is a high possibility that Al atoms belonging to hexacoordinate are distributed on the surface of the skeleton.

High silica zeolite:
The obtained PLS-3 was heated to 500 ° C. at a rate of 1 ° C./min using an electric furnace in the atmosphere, and subjected to heat treatment (calcination) for 2 hours. The structure changed to a powder X-ray diffraction pattern characterized by a powder X-ray diffraction pattern of CDS-3 (top) and a high silica FER type zeolite simulation pattern (bottom). As a result of identification, this substance was found to be the same as FER type zeolite having a known structure. In firing, it is preferable to circulate air in order to efficiently fire the organic amine. This zeolite is called CDS-3.

The proof that the compound thus produced is a zeolite having a pore structure is carried out by ²⁹ Si DDMAS NMR and gas adsorption measurement. The ²⁹ Si DDDMA NMR spectrum of CDS-3 is shown in FIG. A peak attributed to the Q4 structure was observed in the spectrum. In addition, a slight peak attributed to the Q2 structure was also observed, which is considered to be a signal from Si nuclei distributed on the crystal outer surface of the SEM diagram.

  Normally, zeolite has a completely closed Si—O network structure except for the outer surface of the crystal, so that only Q4 structure appears. This also shows that the local structure is due to the pore structure unique to zeolite. The results of examining the isothermal adsorptivity of argon gas of this zeolite are shown in the Ar gas adsorption isotherm curve (left) of FIG. 13 and the pore distribution obtained by NLDFT analysis (right). .

The zeolite obtained in the present invention shows that the gas adsorption performance is high. From the analysis by argon gas adsorption, the BET specific surface area is 460 m ² / g (STP) and NLDFT (nonlinear density functional method). It was estimated that there was a sharp pore distribution at 5.1 mm. In addition, when nitrogen gas adsorption measurement was performed on the PLS-3 heated at an arbitrary temperature and stepped into a zeolite, the nitrogen gas isotherm after the heat treatment at an arbitrary temperature of the PLS-3 in FIG. As shown, it was found that the dehydration polycondensation reaction proceeded at 250 ° C. or higher, resulting in zeolitic formation. Further, the BET specific surface area showed the largest value during the heat treatment at 300 ° C., and reached 580 m ² / g (STP).

  Further, when SEM observation was performed on this CDS-3, the morphology was very small crystals at the submicron level as shown in the SEM image of FIG. It was the next agglomerate and was basically the same as the morphology of PLS-3 before firing.

Al-containing zeolite:
When PLS-3 into which an Al source was introduced was calcined in the same manner, it was found from the powder XRD pattern that it could be distinguished from FER type zeolite but changed to compound Al-CDS-3. FIG. 15 shows a powder X-ray diffraction pattern of Al-CDS-3 obtained by firing novel crystalline layered silicate Al-PLS-3 (Run No. 15). The proof that Al element is introduced into the skeleton of Al-CDS-3 is the same as that of Al-PLS-3, and the Al content is 57.7 ppm from the ²⁷ Al-MAS NMR spectrum shown in FIG. A signal due to tetracoordination was observed, which was confirmed by Al atoms remaining in the skeleton without escape. Moreover, although the peak resulting from 6-coordination is observed at -1.0 ppm, the relative intensity is decreased with respect to the 4-coordinate peak as compared with Al-PLS-3.

The present invention has the following effects.
(1) The crystalline layered silicate of the present invention has a novel crystal structure having a silicon 5-membered ring structure and a high silica content. For example, solid for metal support, separation / adsorbent, shape selection It can be used for a wide range of applications such as conductive solid catalysts, ion exchangers, chromatographic filler materials and chemical reaction fields.
(2) By subjecting this crystalline layered silicate to a dehydration polycondensation reaction, a FER type zeolite that is easily suitable for industrial use and has a high specific surface area can be obtained.
(3) The method of the present invention is easier to synthesize than the conventional method of producing a high silica type FER type zeolite by one-step synthesis by hydrothermal synthesis, and crystals can be obtained within 48 hours. Highly superior as an efficient and low-cost manufacturing technology.
(4) In the adsorption isotherm curve, in the region where the relative pressure (P / P ₀ > 0.9) is high, a significant increase in the amount of adsorption not observed in ordinary zeolite was observed. Very large and advantageous for pressure control of gas adsorption.
(5) The structural change to FER type zeolite can occur at a temperature (250 ° C. or higher) that is considerably lower than the general calcining temperature (500-600 ° C.). A FER-type zeolite having

  EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples.

Hereinafter, the powder X-ray diffraction (XRD) pattern was measured using a Mac Science M21X and using Cu Kα rays in a range of 2θ = 3-60 ° by a step scan method with an interval of 0.02 °. For SEM image observation, HITACH S-800 was used, and the sample was previously ion-coated and then observed at an acceleration voltage of 15 kV. Bruker BioSpin Corporation ANANCE400WB was used for the measurement of ²⁹ Si DDMAS NMR, ¹³ C CPMAS NMR, and ¹³ C DDMAS NMR. For Ar gas adsorption measurement and nitrogen gas adsorption measurement, Autosorb 1-MP manufactured by Cantachrome Co., Ltd. was used, and measurement was performed at a liquid argon temperature of 87K and a liquid nitrogen temperature of 77K, respectively. For thermal analysis, TG-DTA2000 manufactured by Bruker AXS was used.

(Synthesis of novel crystalline layered silicate PLS-3)
In this example, the synthesis of kanemite was performed by immersing 30 g of commercially available crystalline layered sodium silicate, specifically SKS-6 (manufactured by Tokuyama Siltech Co., Ltd.) in 500 ml of distilled water at room temperature for 3 hours. Only the precipitate separated by centrifugation was taken out and dried by a dryer at 50 ° C. for 12 hours.

The acid treatment of kanemite was carried out by stirring 10 g of kanemite powder crystals in 300 ml of 1.0 M hydrochloric acid aqueous solution for 2 hours. The H-kanemite after acid treatment has a chemical composition of Si ₈ O ₁₆ (OH) ₄ and has a structure in which sodium ions and water molecules are removed from the interlayer. The powder X-ray diffraction pattern of this kanemite gave a diffraction peak position and a diffraction intensity as shown in FIG.

  0.5 g of this H-shaped kanemite powder and 0.799 g (TEAOH / Si = 0.15) of a 20 wt% concentration tetraethylammonium (TEAOH) aqueous solution (SIGMA-ALDRICH Corp. SIGMA-ALDRICH Japan K.K.) The sample was added to an autoclave (manufactured by Parr) having an inner volume of 23 ml having a PEFE Teflon (registered trademark) inner cylinder container. FIG. 3 schematically shows the state in the autoclave in the solid phase reaction.

In addition, since the TEAOH reagent used was an aqueous solution, 0.639 g of H ₂ O (molar ratio converted H ₂ O / Si = 4.87) was included in association with TEAOH from its concentration. become. The autoclave thus prepared was heated in an oven at 170 ° C. for 24 hours. After completion of the heating, the product was sufficiently cooled, the product in the autoclave was separated by suction filtration, and dried at 60 ° C. to obtain a powdery final product. The yield was almost 100% based on the silica source, and the product color was white. The powder X-ray diffraction pattern of the product obtained by this solid-phase reaction has a relationship between the diffraction peak position shown in Table 4 and the relative intensity, and is given as shown in FIG.

  In this example, the Run No. in Table 5 was used. 2 is supported. As other conditions, the Run No. in Table 5 was used. 1 and no. No. 3, no. When synthesis was attempted under the conditions indicated by Run 9, run no. 1 to No. Under the condition of 8, PLS-3 was obtained as a product. At this time, no. 1 to No. A series of 9 powder X-ray diffraction patterns is shown in FIG.

The proof that the compound PLS-3 produced in this way is lamellar was performed with ²⁹ Si DDMAS NMR and powder XRD. The following analysis data was obtained by analyzing with the sample of Example 1 described later. ²⁹ Si DDMAS NMR showing a local structure composed of Si and surrounding O of novel layered silicate PLS-3 (Run No. 2) and high silica FER type zeolite CDS-3 obtained by calcining it The spectrum is shown in FIG. In the spectrum of PLS-3, a peak attributed to Q3 (−102.4 ppm) and a peak attributed to the Q4 structure (−108.6, −112.1, −116.4 ppm) were observed.

  Normally, zeolite is a completely closed Si-O network, so all are Q4. The inclusion of Q3 indicates that the network is partially interrupted and means that the silicate has a layered structure. Furthermore, from a crystal structure analysis based on the powder XRD data, a crystal structure similar to the conceptual structure shown in FIG. 6 (schematic diagram showing the crystal structure of the novel layered silicate PLS-3) was obtained. It became clear that it was a layered structure consisting of structures. From the analysis, it was found that the lattice constants were a = 13.994Å, b = 7.417Å, and c = 23.337Å. Here, the lattice constant was determined using indexing software DICVOL91. In addition, the structural analysis of PLS-3 was performed using the structural model of FER type zeolite as an initial value, and refined the structure by the Rietveld method using multipurpose pattern fitting software RIETRAN-2000.

In addition, this ^PLS-3, shows a spectrum obtained by 13 C-CPMAS and ¹³ C-DDMAS NMR measurement in FIG. A peak derived from the ethyl group of the TEAOH molecule was observed at 51.4 ppm, and a peak derived from the methyl group was observed at 8.7 ppm. From this, it became clear that TEAOH molecules were included in the crystal of the product PLS-3.

  Further, when TG-DTA measurement was performed on this PLS-3, as shown in FIG. 8, a moderate weight loss of about 11 wt% was observed from room temperature to 250 ° C. due to desorption of adsorbed water. . Thereafter, an exothermic peak was observed over a temperature range of 250 to 370 ° C., and a weight loss of about 11 wt% was observed. Therefore, it can be understood that TEAOH molecules are burned and desorbed in this temperature range.

  Further, when SEM observation was performed on this PLS-3, the morphology is shown in FIG. 9 (SEM image of the novel layered silicate PLS-3 and the high silica zeolite CDS-3 obtained by firing it). Thus, it was clarified that the crystals were very small at the submicron level, and they were agglomerated to form higher-order aggregates of about several microns. Further, when the synthesis conditions were examined and a synthesis condition map of TEAOH / Si-heating time at a heating temperature of 170 ° C. was created, the results shown in FIG. 10 were obtained as the PLS-3 generation region. . In the figure, ◯: good crystallinity, Δ: low crystallinity, x: amorphous.

(Synthesis of novel crystalline layered silicate PLS-3)
In the production method shown in Example 1, a 35 wt% concentration of tetraethylammonium (TEAOH) aqueous solution (SIGMA-ALDRICH Corp., SIGMA-ALDRICH Japan K.K.) was used, and Run No. described in Table 5 was used. 10 to No. Except as described in 13, the synthesis was carried out under the same conditions as in the production method of Example 1. As a result, Run No. PLS-3 was obtained under 10 conditions. No. at this time. 10 to No. A series of 13 powder X-ray diffraction patterns are shown in FIG.

(Synthesis of novel crystalline layered silicate Al-PLS-3)
In the production method shown in Example 1, sodium aluminate (manufactured by Wako Pure Chemical Industries, Ltd.) was added as an Al source so that Si / Al = 25. Specifically, the Run No. described in Table 5 is shown. The synthesis was carried out under the same conditions as in the production method of Example 1 except that described in 17, and Al-PLS-3 was obtained as a product under all conditions. FIG. 15 shows a powder X-ray diffraction pattern of Al—CDS-3 obtained by firing this.

In order to confirm that Al element was introduced into the skeleton of Al-PLS-3, it was examined by ²⁷ Al-MAS NMR spectrum (FIG. 11). Since a peak attributed to the 4-coordinated structure of Al (AlO ₄ ) was observed at 52.4 ppm and a peak attributed to the 6-coordinated structure (AlO ₆ ) was observed at 6.6 ppm, the Si atoms in the silica skeleton were It was confirmed that it was partially replaced by Al atoms.

(Synthesis of novel crystalline layered silicate Al-PLS-3)
In the production method shown in Example 3, sodium aluminate was added so that Si / Al = 50. 14 to No. The synthesis was carried out under the same conditions as in the production method of Example 1 except that described in 17, and Al-PLS-3 was obtained as a product under all conditions. The powder X-ray diffraction pattern at this time is shown in FIG.

(Preparation of high silica zeolite CDS-3)
The powder of the crystalline layered silicate PLS-3 shown in Example 1 was heated to 500 ° C. at a rate of 1 ° C./min using an electric furnace in the atmosphere, and heat treatment (baking for 2 hours) ), The structure was changed to a structure showing a powder X-ray diffraction pattern of CDS-3, which is characterized in FIG. As a result of identification, it was found that this substance was the same as the high silica FER type zeolite having a known structure. In firing, it is preferable to circulate air in order to efficiently fire organic amine. In this example, air was introduced into the furnace at a flow rate of 2 L / min during firing.

The proof that the compound thus produced is a zeolite with a pore structure is made by ²⁹ Si DDMAS NMR and gas adsorption measurements. The ²⁹ Si DDMAS NMR spectrum of CDS-3 is shown in FIG. A peak attributed to the Q4 structure was observed in the spectrum. In addition, a slight peak attributed to the Q2 structure was also observed, which is considered to be a signal from Si nuclei distributed on the crystal outer surface of the SEM diagram.

Normally, zeolite has a completely closed Si—O network structure except for the outer surface of the crystal, so that only Q4 structure appears. This also shows that the local structure is due to the pore structure unique to zeolite. FIG. 13 (left) shows the results of examining the isothermal adsorption property of the zeolite for argon gas. The results show that the zeolite obtained in the present invention has high gas adsorption performance. From the argon gas adsorption, the BET specific surface area is 460 m ² / g (STP) and NLDFT (nonlinear density generalized). From the analysis by the functional method, it was estimated that there was a sharp pore distribution at 5.1 mm (FIG. 13 (right)).

In addition, when PLS-3 was heated at an arbitrary temperature and stepped into zeolite, nitrogen gas adsorption measurement was performed. As shown by the nitrogen gas adsorption isotherm in FIG. It was found that the polycondensation reaction progressed and it was converted into zeolite. Further, the BET specific surface area showed the largest value during the heat treatment at 300 ° C., and reached 580 m ² / g (STP).

  Furthermore, when SEM observation was performed on this CDS-3, the morphology was very small crystals at the submicron level as shown in FIG. It was basically the same as the morphology of PLS-3 before firing.

(Preparation of high silica zeolite CDS-3)
The crystalline layered silicate PLS-3 powder shown in Example 1 was heated to 300 ° C. and 800 ° C. at a temperature rising rate of 1 ° C./min using an electric furnace in the atmosphere and held for 2 hours. The heat treatment (firing) was performed. As a result, as shown in the powder X-ray diffraction pattern of high silica zeolite CDS-3 in FIG. 19, FER type zeolite was obtained by calcination at 300 ° C., but some of the FER type zeolite heated to 800 ° C. Although the peak derived from the structure remains, the skeleton was destroyed and became amorphous.

(Preparation of high silica zeolite CDS-3)
0.1 g of the powder of crystalline layered silicate PLS-3 shown in Example 1 is put in a Pyrex (registered trademark) glass tube, using an electric furnace under a vacuum of about 10 ⁻⁵ torr, 1 ° C. / A heat treatment was performed for 2 hours after heating to 500 ° C. at a heating rate of min. Also in this case, as shown in FIG. 19, high silica zeolite CDS-3 was obtained.

(Preparation of Al-containing zeolite CDS-3)
Run No. with an Al source introduced. 15 and no. As for Al-PLS-3 of No. 17, when calcinated in the same manner, it was found from the powder XRD pattern that the Al-PLS-3 was changed to a compound Al-CDS-3 that could be distinguished from FER type zeolite. FIG. 20 shows a powder X-ray diffraction pattern of Al-containing zeolite Al-CDS-3 obtained by firing Al-PLS-3. Run No. For No. 17, from the ²⁷ Al-MAS NMR spectrum (FIG. 11), a peak due to the 4-coordinated structure of Al was observed at 57.7 ppm, so that Al was not distributed and Al was distributed in the skeleton. It was confirmed that

  As described above in detail, the present invention relates to the synthesis of a novel layered silicate by a solid-phase reaction method, a high silica zeolite synthesized using it as a precursor, and a method for producing the same. Compared with the synthesis method of high silica type FER type zeolite by one-step synthesis using hydrothermal synthesis method, zeolite crystals can be obtained in a short time within 48 hours. Thus, it is possible to provide a zeolite synthesis technique by an efficient and low-cost solid phase reaction. INDUSTRIAL APPLICABILITY The present invention is useful as a new technique for producing a high silica type FER type zeolite by a solid phase synthesis method.

Si crystalline layered silicate kanemite, O, a crystal structure model represented by _Na (H 2 _{O) 6} shown. The powder X-ray diffraction pattern of H-type kanemite is shown. It is the schematic which shows the state in the autoclave in a solid-phase reaction. The powder X-ray diffraction pattern of the product obtained by the solid phase reaction (Run No. 2 in Table 5) is shown. The ²⁹ Si DDMAS NMR spectrum of novel layered silicate PLS-3 (Run No. 2 of Table 5) and the high silica FER type | mold zeolite CDS-3 obtained by baking it is shown. It is the schematic showing the crystal structure of novel layered silicate PLS-3. The ¹³ C-CPMAS NMR and ¹³ C-DDMAS NMR spectrum of the novel layered silicate PLS-3 (Run No. 2) are shown. The TG-DTA curve (Run No. 2) of novel layered silicate PLS-3 is shown. The SEM image of novel layered silicate PLS-3 and the high silica zeolite CDS-3 obtained by baking it is shown. A map showing the synthesis conditions and products of the novel layered silicate PLS-3, o: good crystallinity, Δ: low crystallinity, x: amorphous. The ²⁷ Al-MAS NMR spectrum of novel crystalline layered silicate Al-PLS-3 (Run No. 17) and Al-CDS-3 obtained by firing the same is shown. The powder X-ray diffraction pattern (upper) of zeolite CDS-3 obtained by calcining the novel crystalline layered silicate PLS-3 and the simulation pattern (lower) of high silica FER type zeolite are shown. FIG. 2 shows an Ar gas adsorption isotherm curve (left) of high silica zeolite CDS-3 and a diagram (right) showing the pore distribution determined by NLDFT analysis. The nitrogen gas adsorption isotherm after heat-processing at arbitrary temperature of crystalline layered silicate PLS-3 is shown. The powder X-ray-diffraction pattern of the zeolite Al-CDS-3 obtained by baking new crystalline layered silicate Al-PLS-3 (Run No. 15) is shown. According to Example 1, Run No. 1-No. The powder X-ray-diffraction pattern of the product synthesize | combined based on the conditions of 9 is shown. According to Example 2, Run No. 10-No. The powder X-ray-diffraction pattern of the product synthesize | combined based on 13 conditions is shown. According to Example 3, the Run No. in Table 5 14-No. The powder X-ray-diffraction pattern of the product synthesize | combined based on 17 conditions is shown. The powder X-ray-diffraction pattern of the high silica zeolite CDS-3 obtained by baking new layered silicate PLS-3 is shown. The powder X-ray-diffraction pattern of the zeolite Al-CDS-3 containing Al obtained by baking new crystalline layered silicate Al-PLS-3 is shown.

Claims (8)

The crystalline layered silicate kanemite (kanemite) the acid-treated H-type kanemite (H-kanemite), as organic crystallization modifier, a tetraethylammonium hydroxide (TEAOH) aqueous solution, the molar ratio TEAOH / Si = 0. 10-0.35, H ₂ O / Si = 2.26-11.36 In addition, the raw material is subjected to a solid phase reaction in a water vapor atmosphere in a pressure vessel (autoclave), A method for producing a crystalline layered silicate PLS-3, comprising synthesizing a crystalline layered silicate PLS-3 having a relationship between a diffraction peak position shown in Table 1 and a relative intensity .
An aluminate crystal is added to the raw material as an Al source, and a solid phase reaction is performed in a water vapor atmosphere in a pressure vessel (autoclave) to synthesize an Al-containing crystalline layered silicate. Method for producing crystalline layered silicate PLS-3 . To H-kanemite obtained by acid-treating crystalline layered silicate kanemite, the organic crystallization regulator is tetraethylammonium hydroxide (TEAOH) aqueous solution, and the molar ratio is TEAOH / Si = 0.10-0.35, In addition to being in the range of H ₂ O / Si = 2.26-11.36, in a pressure vessel (autoclave), in a temperature range of 160-180 ° C. and heating conditions for 24-72 hours, water vapor The method for producing a crystalline layered silicate PLS-3 according to claim 1, wherein a solid phase reaction is performed in an atmosphere. The method for producing crystalline layered silicate PLS-3 according to claim 2, wherein sodium aluminate crystals are added to the raw material as the Al source in a Si / Al ratio range of 25-50. A crystalline layered silicate PLS-3 was synthesized by the method described in any one of claims 1 to 4, crystals characterized by having a relationship of diffraction peak positions and relative intensities shown in Table 1 Layered silicate PLS-3. Silicic consisting skeletal structure of layered, characterized in that it consists covalent bond Si-O having a containing 5-membered ring, according to claim 5, wherein the crystalline layered silicate PLS-3. The process according to claim 5 or a crystalline layered silicate PLS-3 according to 6, full Erieraito characterized by causing dehydration polycondensation (FER) type zeolite. The crystalline layered silicate PLS-3, was heated at 250 ° C. or higher at or reduced under vacuum atmosphere, dehydration polycondensation to process according to claim 7, wherein the full Erieraito (FER) type zeolite.