JP4348430B2 - Crystalline layered compound and process for producing the same - Google Patents

Description

The present invention relates to a novel crystalline layered compound having a five-membered ring network structure and a method for producing the same, and more specifically, a structure having a regularly arranged silicate skeleton, hydrophobic and having little interlayer interaction The present invention relates to a novel crystalline layered compound having a structure, a method for producing the same, and a structural member containing the compound as a constituent element.
In the field of new-type zeolite synthesis technology represented by high-silica type zeolite, which is expected to be put to practical use as a next-generation multifunctional zeolite, the basic skeleton parts (parts) of these zeolites The present invention provides a novel crystalline layered compound (PLS-1) that can be used as a starting material and a method for producing the same.
The present invention can be used for, for example, a precursor material for zeolite synthesis, a metal-supporting solid, a separation / adsorbent, a shape-selective solid catalyst, an ion exchanger, a chromatographic packing material, or a structural member. In addition to providing a novel crystalline layered compound and a method for producing the same, the present invention is useful for providing a structural member containing the crystalline layered compound as a constituent element.

  In general, zeolite has many micro-level pores regularly arranged at the atomic level, has high heat resistance, and is chemically stable. The aluminosilicate having a skeletal structure of this zeolite, in which a part of Si is substituted with Al, has pores of molecular order (3-10Å) and has a shape-selective adsorption action. Therefore, molecular sieve (molecular sieve) ). So far, in addition to tens of kinds of natural zeolites, various types of zeolites have been synthesized and widely used, for example, in the fields of catalysts, separation adsorbents, ion exchangers and the like. Further, silicalite having a pure silicate skeleton that does not contain aluminum has high hydrophobicity and is used, for example, as a separation adsorbent.

Metallosilicates in which metal atoms are substituted in part of the skeletons of these zeolites are attracting attention as new compounds because they can be added to the properties of metal catalysts in addition to the above characteristics. For example, MFI-type zeolite TS-1 and the like into which titanium is substituted and introduced have also been synthesized (see Patent Document 1).

These zeolites are generally hydrothermally synthesized, that is, a large amount of water and organic crystallization regulators such as an aluminum source, a silica source, alkali metals and amines (a templating agent that forms the pores of the resulting zeolite). Are prepared under a self-pressure by a method of preparing them so as to have a desired chemical composition, enclosing them in a pressure vessel such as an autoclave and heating them (see Non-Patent Document 1).

  However, this hydrothermal synthesis method is often the case of batch synthesis, so in addition to various synthesis conditions for zeolite synthesis, conditions for regularly replacing metal atoms with the framework of the zeolite must be set. Is considered extremely difficult at present. This problem is considered to be due to the fact that a clear design process for material design has not been established in the conventional synthesis method.

  One concept for newly producing a multifunctional zeolite compound is to design a new compound by combining basic framework parts (parts) of layered silicate compounds that are highly ordered at the atomic level and combining them like building blocks. However, it is considered promising to organize (see Non-Patent Document 2). Further, in the prior art documents, conversion from a crystalline layered compound to a microporous material, a detailed crystal structure of the crystalline layered compound HLS, and its characteristics are reported (Patent Document 2, Non-Patent Document). 3).

US Pat. No. 4,410,501 Japanese Patent Application No. 2002-17785 Inorganic Synthesis, Vol. 22, edited by S. L. Holt. Jr (Wiley, New York, 1983) Y. Kiyozumi, F. Mizukami, Y. Akiyama, T. Ikeda, and T. Nishide, Studies in Surface Science and Catalysis, 135H, 02-P-25, 191 (2001) T. Ikeda, Y. Akiyama, F. Izumi, Y. Kiyozumi, F. Mizukami, and T. Kodaira, Chem., Mater. 13, 1286-1295 (2001)

In such a situation, the present inventors, in view of the above-mentioned conventional technology, based on the above technical background and research viewpoint, have drastically solved various problems in the conventional hydrothermal synthesis method in the zeolite synthesis process. As a result of diligent research aimed at developing a new synthesis technology capable of building a clear design process for material design, it has a regularly arranged silicate skeleton and is hydrophobic. The present inventors have succeeded in producing a novel crystalline layered compound having a layered structure with little interlayer interaction, and found that the intended purpose can be achieved by using the crystalline layered compound. It came to complete.
That is, an object of the present invention is to provide a novel crystalline layered compound having a 5-membered ring network structure and a method for producing the same.
Another object of the present invention is to provide a structural member containing the crystalline layered compound as a constituent element.

The present invention for solving the above-mentioned problems is as follows. (1) The chemical composition is represented by the general formula [(Si _18-x · O ₃₈ ) · M _y · (TMA) _z · (H 2 O) _w ] (wherein TMA is Tetraalkylammonium cation, M represents an alkali metal cation, x is 0 ≦ x ≦ 1.2, y is 0.5 ≦ y ≦ 1.5, z is 6 ≦ z ≦ 8, and w is 0.02. ≦ w ≦ 1.5.) And a single-layered skeleton having a nano-sized one-dimensional micropore that forms a covalent network composed of Si atoms and O atoms. A crystalline layered compound characterized in that the lattice spacing of d in the powder X-ray diffraction pattern is at least described in the following table.
d (Å) Relative intensity (peak)
10.47 ± 0.2 vs
8.38 ± 0.15 w
7.34 ± 0.15 m
7.00 ± 0.1 m
6.51 ± 0.1 m
6.45 ± 0.1 s
5.86 ± 0.05 m
5.82 ± 0.04 m
5.66 ± 0.04 w
5.23 ± 0.04 m
5.07 ± 0.04 w
4.90 ± 0.04 s
4.75 ± 0.04 m
4.57 ± 0.04 w
4.40 ± 0.04 m
4.35 ± 0.04 s
4.26 ± 0.04 s
4.19 ± 0.04 vs
4.00 ± 0.04 m
3.94 ± 0.035 s
3.85 ± 0.035 s
3.83 ± 0.035 vs
3.78 ± 0.035 w
3.67 ± 0.035 m
3.63 ± 0.035 s
3.60 ± 0.035 w
3.55 ± 0.035 m
3.51 ± 0.035 m
3.50 ± 0.035 vs
3.48 ± 0.035 vs
3.38 ± 0.035 m
3.34 ± 0.035 w
3.32 ± 0.035 s

(In the table, d represents the lattice spacing. Also, w = weak relative intensity, m = medium phase pair intensity, s = strong relative intensity, vs = very strong relative intensity.)
The present invention also provides (2) the crystalline layered compound of (1) above, wherein the local arrangement of O atoms around the Si atom in the Si—O network is composed of tricoordinate and tetracoordinate, The crystalline layered compound of (1) above containing an alkali metal cation and an organic crystallization regulator in the interlayer void of the crystal structure, and (4) the crystalline layered layer of (1) above having an effective void between layers of 5 mm or more. A preferred embodiment is a compound, (5) the crystalline layered compound of the above (1) having pores composed of a skeleton portion having a silicon 5-membered ring or more.
Moreover, this invention is (6) the manufacturing method of the crystalline layered compound characterized by heating an organic crystallization regulator containing layered silicate in presence of a lot of water.
The present invention also provides (7) the method for producing a crystalline layered compound according to (6), wherein the heating temperature is 100 to 200 ° C. and the reaction time is 3 hours to 30 days, and (8) the organic crystallization regulator is The method for producing a crystalline layered compound according to (6), which is at least one selected from tetramethylammonium salt, tetraethylammonium salt, tetrapropylammonium salt, or quaternary alkylammonium salt of tetrabutylammonium salt and organic amines, Is a preferred embodiment.
Furthermore, the present invention is (9) a structural member comprising the crystalline layered compound according to any one of (1) to (5) as a constituent element.

Next, the present invention will be described in more detail.
The crystalline layered compound according to the present invention is formed of a silicate skeleton having a silicon 5-membered ring structure, and a cation having an ionic radius of 1.0 angstrom or more and an organic amine having a diameter of 3.0 angstrom or more between the parallel layers. It is characterized in that a layer of an organic crystallization adjusting agent such as a kind is interposed. The above-mentioned silicon five-membered ring structure is composed of a repeating unit of Si—O tetrahedral coordination based on silicon, and the cation is preferably K, for example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
When conceptually explaining the crystalline layered compound of the present invention, as shown in FIG. 1, this layered compound has a repeating unit of tetrahedral coordination of Si—O in a silicate basic structure, and has a fine structure due to a 5-membered silicon ring. Holes are included in the silicate. Then, a cation layer having an ionic radius of 1.0 angstrom or more and a layer of an organic crystallization adjusting agent such as organic amines having a diameter of 3.0 angstrom or more are interposed between the silicate layers to constitute the whole.

In the method of the present invention, a silica source as a raw material, an alkali source having an ionic radius of 1.0 angstrom or more (Na, K, Li, etc.), an organic crystallization regulator such as an organic amine having a diameter of 3.0 angstrom or more, and a solvent An organic crystallization regulator-containing layered silicate is synthesized from a mixed solution of raw materials consisting of: In the present invention, as the silica source, for example, SiO ₂ (specifically, for example, Cab-O-Sil M5, manufactured by CABOT Co.) or the like is preferably used, but is not limited thereto. is not.

As the organic crystallization modifier, any conventionally known one can be used as long as it can be accessed between the layers and can be spread between layers, or has a function as a template for forming a silicate skeleton structure. . As the organic crystallization regulator, for example, quaternary alkyl ammonium salts such as tetramethylammonium salt, tetraethylammonium salt, tetrapropylammonium salt, tetrabutylammonium salt, amines, and phosphonium ions (R ₄ P ⁺ : R represents hydrogen, an alkyl group or aryl group having 10 or less carbon atoms, P represents phosphorus, and the like . Among these, in the present invention, for example, a tetramethylammonium salt is preferably used as the organic crystallization regulator.

Further, in the method of the present invention, the reaction component and the reaction molar ratio may be appropriately determined depending on the composition of the crystalline layered compound represented by the general formula, and are not particularly limited. Is, for example, a molar ratio of SiO ₂ : M: TMA: H ₂ O = 1.0: 0.22: 0.02: 8.5 (where M is an alkali metal cation and TMA is a tetraalkylammonium cation). Represents an ion).

In the reaction process from a sol-gel mixed solution formed by mixing raw materials to a crystalline layered compound, a hydrothermal synthesis method is employed in which heat treatment is performed in the presence of a large amount of water. For example, it is carried out by heating a reaction vessel such as an autoclave. In this case, the heating temperature is not particularly limited, but is preferably 100-200 ° C, more preferably 140-170 ° C, and the reaction time is preferably 3 hours-30 days, more preferably 3-14 days. These are required to be set to optimum conditions according to the reaction components and the reaction molar ratio. The product obtained is washed with acetone and water and dried.

The compound produced in this way forms a network by covalent bonding of Si atoms and O atoms, has a single layered skeleton having one-dimensional nano-sized pores as a basic structure, and a powder X-ray diffraction pattern The lattice spacing of d in FIG. 4 has a specific value shown in the examples described later. It can be proved that this compound is layered by nuclear magnetic resonance ( ²⁹ Si-MAS NMR) in ²⁹ Si nucleus, SEM observation and powder XRD measurement. The following analysis data was obtained by analyzing the sample of Example 1 to be described later. From the coordination environment of O around Si (FIG. 2) analyzed by ²⁹ Si-MAS NMR, The peaks attributed to Q3 and Q4 were observed.

Here, when Q3 is focused on one Si atom in the silicate skeleton, there are three bonds having an atomic arrangement of -O-Si (-represents a bond) around it. That there is one. Since Si is tetrafunctional, in Q3, the remaining one functional group is not an atomic arrangement that becomes -O-Si. In this case, O becomes O ^- or OH and becomes a terminal. Normally, zeolite is a completely closed cage network, so all are Q4. The inclusion of Q3 indicates that the network is partially interrupted and means that the silicate produced by the method of the present invention has a layered structure. The presence of a 5-membered silicon ring was clarified by obtaining a crystal structure similar to the conceptual structure shown in FIG. 1 from powder XRD structural analysis.

  According to the present invention, (1) a novel crystalline layered compound having a 5-membered ring network structure and a method for producing the same can be provided. (2) The crystalline layered compound of the present invention has a regularly arranged silicate skeleton. Because it has a structure that is hydrophobic and has little interaction between layers, for example, precursor materials for zeolite synthesis, solids for metal support, separation / adsorbents, shape-selective solid catalysts, ion-exchange agents, and chromatography packing It is useful as a material such as an agent or a structural member, and (3) it is possible to sandwich atoms and molecules serving as guests between the layers, thereby providing a highly functional porous material such as mesoporous silicate. An exceptional effect is that it is possible to produce and provide possible nano-sized parts.

  Next, the present invention will be specifically described based on examples, but the present invention is not limited thereto.

(1) Measuring method The powder X-ray diffraction (XRD) pattern was obtained by continuous scanning at intervals of 0.02 ° using CuKα rays using MX18VT manufactured by Mac Science. For thermogravimetric analysis, TGDTA2000 from Mac Science was used, and from Bruker BioSpin AMX-500 for ²⁹ Si-MAS NMR. The nitrogen adsorption isotherm was measured at 77K by Nippon Belsoap 36.

(2) Production of crystalline layered compound 10.0 g of SiO ₂ (Cab-O-Sil M5, manufactured by CABOT Co.) was taken and 22.0 g of 15% TMAOH (tetramethylammonium hydroxide), 0.5N Of KOH 5.0 g, H ₂ O 25.0 g, and 1,4-dioxane 50.0 g. This was stirred well for about 1 hour, transferred to an SUS316 autoclave (internal volume 300 ml) having a Teflon (registered trademark) inner cylinder, and heat-treated at 150 ° C. for 10 days. After taking out from the autoclave, it was washed with acetone and water and dried at a temperature of 70 ° C. for 12 hours to obtain a powdery product.

(3) Characteristics of crystalline layered compound It was confirmed by ²⁹ Si-MAS NMR, SEM photograph and XRD measurement that this product was a layered compound. FIG. 2 shows the arrangement environment of O around Si analyzed by ²⁹ Si-MAS NMR. As described above, peaks attributed to Q3 and Q4 were observed in the spectrum, indicating that the obtained silicate had a layered structure. This product gave an XRD pattern characterized by intensity data as shown in the table below (this product is abbreviated as PLS-1). Further, when this PLS-1 powder was subjected to differential thermal-thermogravimetric analysis, an exothermic reaction derived from desorption of TMA ions from the interlayer was observed in the range of 300 to 500 ° C. The weight loss associated with the desorption of TMA was about 14 wt%.

d (Å) Relative intensity (peak)
10.47 ± 0.2 vs
8.38 ± 0.15 w
7.34 ± 0.15 m
7.00 ± 0.1 m
6.51 ± 0.1 m
6.45 ± 0.1 s
5.86 ± 0.05 m
5.82 ± 0.04 m
5.66 ± 0.04 w
5.23 ± 0.04 m
5.07 ± 0.04 w
4.90 ± 0.04 s
4.75 ± 0.04 m
4.57 ± 0.04 w
4.40 ± 0.04 m
4.35 ± 0.04 s
4.26 ± 0.04 s
4.19 ± 0.04 vs
4.00 ± 0.04 m
3.94 ± 0.035 s
3.85 ± 0.035 s
3.83 ± 0.035 vs
3.78 ± 0.035 w
3.67 ± 0.035 m
3.63 ± 0.035 s
3.60 ± 0.035 w
3.55 ± 0.035 m
3.51 ± 0.035 m
3.50 ± 0.035 vs
3.48 ± 0.035 vs
3.38 ± 0.035 m
3.34 ± 0.035 w
3.32 ± 0.035 s

(In the table, d represents the lattice spacing. Also, w = weak relative intensity, m = medium phase pair intensity, s = strong relative intensity, vs = very strong relative intensity.)
The nitrogen desorption / adsorption isotherm of PLS-1 is shown in FIG. In the figure, the upper graph is the desorption isotherm, and the lower graph is the adsorption isotherm. From this figure, it can be seen that PLS-1 has a small adsorption capacity. FIG. 4 shows an electron micrograph image of PLS-1. It can be seen that PLS-1 has a thin scaly crystal form of about 1 to 5 μm and has a cleavage plane peculiar to the layered structure.

  In Example 1, the crystalline layered compound was produced under the same conditions except that PLS-1 was synthesized by heat treatment at 160 ° C. for 5 days. Also in this example, PLS-1 was obtained as a product.

  In Example 1, the crystalline layered compound was produced under the same conditions except that PLS-1 was synthesized by heat treatment at 160 ° C. for 10 days. Also in this example, PLS-1 was obtained as a product.

  In Example 1, the crystalline layered compound was produced under the same conditions except that PLS-1 was synthesized by heat treatment at 170 ° C. for 5 days. Also in this example, PLS-1 was obtained as a product.

  In Example 1, the crystalline layered compound was produced under the same conditions except that PLS-1 was synthesized by heat treatment at 170 ° C. for 10 days. In this example, a single phase of PLS-1 was not generated, and some PLS-1 and amorphous silica were generated. This is probably because the heat treatment has progressed too much and PLS-1 has changed to a high-density amorphous phase, so that a single phase of PLS-1 has not been generated.

Reference Example Manufacture of Zeolite 3.0 g of this PLS-1 was placed in a Pyrex (registered trademark) or quartz glass tube with an inner diameter of 25 mm, connected to a vacuum line, and from room temperature to 500 ° C. under a vacuum of 5 × 10 ⁻⁶ torr. Heat treatment was carried out in three steps: heating for 4 hours, holding for 4 hours, and cooling to room temperature for 1 hour, to obtain a high-silica type zeolite as a gray powder as a product. The weight at this time was 2.55 g. This product had diffraction peaks as shown in the following table from the powder XRD pattern. The zeolite and the layered silicate PLS-1 are thin scaly crystals having a side of about 12 μm and a thickness of about 0.2 μm from their scanning electron micrographs, and the crystal morphology of both is almost the same. This indicates that zeolite was produced by PLS-1 having a layered structure and topological structural change.
d (Å)
9.25 ± 0.05
8.85 ± 0.05
7.67 ± 0.05
6.85 ± 0.05
6.14 ± 0.05
4.74 ± 0.05
4.65 ± 0.05
4.49 ± 0.05
4.40 ± 0.05
4.10 ± 0.05
3.90 ± 0.05
3.84 ± 0.05
3.71 ± 0.05
3.44 ± 0.05
3.34 ± 0.05
3.26 ± 0.05
3.08 ± 0.05

  As described above in detail, the present invention relates to a crystalline layered compound and a method for producing the same, and according to the present invention, the structure has a regularly arranged silicate skeleton, is hydrophobic, and has few interlayer interactions. It is possible to provide a novel crystalline layered compound having the above and a method for producing the same. This crystalline layered compound is useful, for example, as a precursor material for zeolite synthesis, a metal-supporting solid, a separation / adsorbent, a shape-selective solid catalyst, an ion exchange agent, a chromatographic filler, or a structural member. It is. Further, not only atoms and molecules serving as guests can be sandwiched between the layers, but also the silicate skeleton itself has a metastable structure, so that it can be easily fragmented. According to the present invention, it is possible to obtain a nano-sized part having a regular structure that is optimal for the production of a highly functional porous material such as mesoporous silicate, whereby a structural member at the atomic level can be constructed.

The conceptual diagram of the crystalline layered compound represented by the general formula of this invention is shown. The analysis result by 29Si-MAS NMR of the crystalline layered compound of the structure shown in FIG. 1 is shown. The nitrogen desorption / adsorption isotherm of PLS-1 obtained in the present invention is shown (the upper graph is the desorption isotherm and the lower graph is the adsorption isotherm). It is a scanning electron microscope (SEM) photograph of PLS-1 obtained by the present invention.

Claims (9)

The chemical composition is represented by the general formula [(Si _18-x · O ₃₈ ) · M _y · (TMA) _z · (H ₂ O) _w ] (wherein TMA is a tetraalkylammonium cation and M is an alkali metal cation. X represents 0 ≦ x ≦ 1.2, y represents 0.5 ≦ y ≦ 1.5, z represents 6 ≦ z ≦ 8, and w represents a range of 0.02 ≦ w ≦ 1.5. And a single-layered skeleton having a nano-sized one-dimensional micropore as a basic structure, and having a basic structure, and forming a covalent network composed of Si atoms and O atoms, and d in the powder X-ray diffraction pattern A crystalline layered compound having a lattice spacing described in at least the following table.
d (Å) Relative intensity (peak)
10.47 ± 0.2 vs
8.38 ± 0.15 w
7.34 ± 0.15 m
7.00 ± 0.1 m
6.51 ± 0.1 m
6.45 ± 0.1 s
5.86 ± 0.05 m
5.82 ± 0.04 m
5.66 ± 0.04 w
5.23 ± 0.04 m
5.07 ± 0.04 w
4.90 ± 0.04 s
4.75 ± 0.04 m
4.57 ± 0.04 w
4.40 ± 0.04 m
4.35 ± 0.04 s
4.26 ± 0.04 s
4.19 ± 0.04 vs
4.00 ± 0.04 m
3.94 ± 0.035 s
3.85 ± 0.035 s
3.83 ± 0.035 vs
3.78 ± 0.035 w
3.67 ± 0.035 m
3.63 ± 0.035 s
3.60 ± 0.035 w
3.55 ± 0.035 m
3.51 ± 0.035 m
3.50 ± 0.035 vs
3.48 ± 0.035 vs
3.38 ± 0.035 m
3.34 ± 0.035 w
3.32 ± 0.035 s

(In the table, d represents the lattice spacing. Also, w = weak relative intensity, m = medium phase pair intensity, s = strong relative intensity, vs = very strong relative intensity.)   The crystalline layered compound according to claim 1, wherein the local coordination of O atoms around the Si atom in the network by a silicon-oxygen covalent bond (Si—O) is composed of tricoordinate and tetracoordinate.   The crystalline layered compound according to claim 1, comprising an alkali metal cation and an organic crystallization modifier in an interlayer void of the crystal structure.   The crystalline layered compound according to claim 1, wherein an effective void between layers is 3 mm or more.   The crystalline layered compound according to claim 1, which has pores composed of a skeleton portion having a silicon 5-membered ring or more.   A method for producing the crystalline layered compound according to any one of claims 1 to 5, comprising a silica source, an alkali source having an ionic radius of 1.0 angstrom or more, an organic crystallization regulator having a diameter of 3.0 angstrom or more, And a method for producing a crystalline layered compound, which comprises heat-treating a mixed solution of raw materials comprising a solvent and a large amount of water.   The method for producing a crystalline layered compound according to claim 6, wherein the heating temperature is 100 to 200 ° C and the reaction time is 3 hours to 30 days. The organic crystallization regulator is at least one selected from a tetramethylammonium salt, a tetraethylammonium salt, a tetrapropylammonium salt, or a quaternary alkylammonium salt of a tetrabutylammonium salt, and an organic amine. A method for producing a crystalline layered compound.   A structural member comprising the crystalline layered compound according to claim 1 as a constituent element.