JP3367145B2 - MEMBRANE SYNTHETIC ZEOLITE AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic membrane zeolite and a method for producing the same. More particularly, gas separation membranes,
The present invention relates to a membrane-like synthetic zeolite that is effectively used as a catalyst, an adsorbent, etc., and a method for producing the same.

[0002]

2. Description of the Related Art Zeolites are widely used as catalysts and adsorbents because of their properties such as molecular sieving properties and solid acidity. In recent years, synthetic membrane zeolites have also been studied, and due to their heat resistance and chemical resistance, they are also attracting attention as materials for gas separation membranes.

[0003] Forming a zeolite into a membrane has many advantages not only in that it can be used as a gas separation membrane, but also when it is used as a catalyst or an adsorbent. That is, compared with zeolite formed into pellets, the apparent contact area is large, and since a binder can be eliminated, there are advantages such as a small mass per unit volume.

[0004] A method for producing a membranous zeolite is disclosed in Japanese Unexamined Patent Publication No.
No. 59-213615, No. 60-28826, No. 60-129119, No. 63-291809, Japanese Patent Application Laid-Open No. 4-227826, etc., all of which use alumina or the like. substrate is required. The use of such a substrate has problems such as a limitation in the range of use as a separation membrane such that it cannot be developed on other substrates, and an increase in the weight of the separation membrane. Also, zeolite species produced by these methods include zeolite A, zeolite X or Y, mordenite, ZSM-5, and the like.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a membranous synthetic zeolite, which is ZSM-35, which can be produced without using an alumina substrate or the like, and a method for producing the same. be.

[0006]

SUMMARY OF THE INVENTION According to the present invention, during synthesis
Self- sustaining membranous synthetic zeolite ZSM-
35 are provided.

Such membranous synthetic zeolite has the following composition: SiO ₂ /Al ₂ O ₃ =30-120 alkali metal source/SiO ₂ =0.2-0.5 crystallization agent/SiO ₂ =0.02-0.5 H ₂ O/SiO ₂ = An aqueous mixture consisting of a silica source, an alumina source, an alkali metal source, a tetramethylammonium salt as a crystallization agent and water having a molar ratio of 80-250 is sealed in a pressure vessel ,
Heat up to the hydrothermal synthesis temperature at a rate of temperature rise of °C/min, 150-200
By maintaining the temperature at the hydrothermal synthesis temperature of 10° C., it is produced in a film-like state by itself during synthesis without requiring a substrate or the like during production.

As the silica source, silica sol, sodium silicate aqueous solution (including aqueous solution of water glass), silica powder, silicic acid and the like can be used, but silica sol and sodium silicate aqueous solution are preferably used. . As an alumina source, Al ₂ O ₃ derived from sodium aluminate is preferably used. Moreover, oxides, such as sodium and potassium, are used as an alkali metal source.

A crystallization agent is a template agent (structure control agent).
It is also called, and constitutes one of the factors that greatly contribute to the crystal structure of zeolite. In the present invention, tetramethylammonium salt is used. As the tetramethylammonium salt, its bromide, chloride and iodide are generally used, but tetramethylammonium bromide is preferably used from the viewpoint of price.

When other tetraalkylammonium salts are used, film-like ZSM-35 cannot be obtained. For example, when tetraethylammonium salts and tetrabutylammonium salts are used, only powdery mordenite is obtained. No, and when the tetrapropylammonium salt is used, only ZSM-5 is obtained, albeit in the form of a film.

An aqueous mixture consisting of a silica source (SiO ₂ ), an alumina source (Al ₂ O ₃ ), an alkali metal source, a tetramethylammonium salt crystallizing agent and water was prepared in the following molar ratios (preferred molar ratios in parentheses): ratio), and if an aqueous mixture outside this range is used, only various powdered synthetic zeolites (analcyme, mordenite, etc.) can be obtained. _SiO2 / _Al2O3 = ₃₀ to 120 (60 to 100) Alkali metal source/ _SiO2 = 0.2 to 0.5 (0.2 to 0.4) Crystallizer/ _SiO2 = 0.02 to 0.5 (0.1 to 0.3) _H2O / _SiO2 = 80-250 (100-200)

[0012] The synthetic mother liquor, which is such an aqueous mixture,
After enclosing in a pressure-resistant container, raise the temperature to the hydrothermal synthesis temperature, 15
about 12 to a hydrothermal synthesis temperature of 0-200°C, preferably 170-200°C.
Hydrothermal synthesis is performed by holding for ~60 hours. At this time, the heating rate to the hydrothermal synthesis temperature is preferably 0.5 to 5 ° C./min. At a higher heating rate, although ZSM-35 is formed, it is powdery and does not form a film. .

[0013] The synthetic zeolite obtained by the above method is formed on the upper surface of the powdered zeolite deposited on the bottom of the container, so that it stands alone during synthesis and does not require a support or the like. Moreover, this membranous synthetic zeolite has a thickness of several tens to hundreds of tens of micrometers, and its structure was confirmed to be ZSM-35 from the results of X-ray diffraction.

[0014]

INDUSTRIAL APPLICABILITY The zeolite synthesized by hydrothermally synthesizing a synthetic mother liquor using a tetramethylammonium salt as a crystallization agent in a pressure-resistant vessel is in the form of a membrane, and is ZSM-35. A synthetic zeolite can be obtained without using an alumina substrate or the like. The resulting membranous
Since ZSM-35 has excellent heat resistance and high alkylation activity for aromatic hydrocarbons, it can be used not only as a catalyst but also as an adsorbent and separation membrane.

[0015]

EXAMPLES The present invention will now be described with reference to examples.

Examples 1-6, Comparative Examples 1-4 Water glass as a silica source, sodium aluminate as an alumina source, sodium oxide as an alkali metal source, and various tetraalkylammonium bromides as crystallization agents, respectively. A synthetic mother liquor having a composition ratio between components shown in the table below was enclosed in a pressure vessel. The mixture was placed in an oven, heated to a predetermined temperature at a heating rate of 2° C./min, and maintained at this temperature for a predetermined period of time for hydrothermal synthesis. _{SiO2 / Na2O} / Crystallizer _H2O / Hydrothermal Synthesis Condition Example Crystallizer _{Al2O3SiO2 / SiO2SiO2} Temperature (°C) _Time (hrs) Example 1 ( _CH3 ) ₄ NBr 80.8 0.47 0.10 119 170 60 〃 ２ 〃 69.7 〃 0.12 118 〃 48 〃 ３ 〃 60.0 0.48 0.14 120 180 36 〃 ４ 〃 88.2 0.47 0.16 148 〃 24 〃 ５ 〃 80.2 〃 〃 149 〃 18 〃 ６ 〃 69.2 〃 0.08 148 190 12 Comparative Example 1 - 60.1 0.48 0 120 170 60 〃 2 (C ₂ H ₅ ) ₄ NBr 80.5 0.47 0.10 119 〃 48 〃 3 (C ₃ H ₇ ) ₄ NBr 89.2 〃 0.08 146 180 36 〃 4 (C ₄ H ₉ ) ₄ NBr 88.0 〃 0.10 148 〃 24

In each example, the product was film-like ZSM-35, whereas Comparative Example 1 was powdery analcyme, Comparative Example 2 was powdery mordenite, and Comparative Example 3 was film-like ZSM-35. ZSM-5 and Comparative Example 4 produced powdery mordenite, which was confirmed from the external appearance and X-ray diffraction of each pulverized product.

The results of X-ray diffraction of film-like ZSM-35 are as follows.
shown in Diffraction angle Diffraction intensity ratio2θ I/I ₀ 9.30 100 12.66 63 12.75 63 13.38 67 15.40 27 17.84 12 22.24 50 22.82 31 23.04 20 23.54 39 23.78 37 24.36 26 25.04 93 25.54 85 26.12 22 27.02 56 28.54 29 29.26 22 45.66 2 47.20 9

Claims (2)

(57) [Claims] 1. Membrane-like synthetic zeolite ZSM-35 , which is self-supporting as zeolite alone during synthesis. _2. The molar ratio of SiO2 /Al2O3 =30-120 alkali metal source/SiO2 _{= 0.2-0.5} crystallization agent/ _SiO2 = _0.02-0.5 H2O / _{SiO2 =} 80-250 . An aqueous mixture consisting of a silica source, an alumina source, an alkali metal source, a tetramethylammonium salt as a crystallization agent, and water is sealed in a pressure vessel, and hydrothermally heated at a rate of 0.5 to 5°C/min.
It is characterized by raising the temperature to the synthesis temperature and maintaining it at the hydrothermal synthesis temperature of 150 to 200 ° C, which is self-supporting with zeolite alone during synthesis.
A method for producing membrane-like synthetic zeolite ZSM-35 .