JPS6225606B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a novel crystalline aluminosilicate zeolite containing organic nitrogen cations within its structure. More specifically, the present invention relates to a method for producing crystalline aluminosilicate zeolite, which is characterized by using a raw material mixture containing diglycolamine as an organic nitrogen cation source. Zeolites, commonly known as molecular sieves, have a three-dimensional network structure in which silica and alumina share oxygen, and the ratio of oxygen atoms to the total of aluminum and silicon atoms is equivalent to 2. The negative electrical properties of these SiO ₄ tetrahedra are usually balanced by alkali metal cations, especially sodium or potassium. Zeolite was first discovered as a naturally occurring material, but later it became possible to synthesize it by hydrothermally treating a mixture of silica, alumina, and alkali metals at temperatures above 100°C. By changing the heat treatment conditions, zeolites with structures similar to natural products or many zeolites that have not previously existed in nature have been synthesized. Recently, Barrer et al. announced a method for producing zeolite in which part of the alkali metal is replaced by an organic nitrogen compound. This zeolite is characterized by containing organic nitrogen cations used as raw materials in its structure, and when tetramethylammonium compounds are used, erionite, offretite,
They announced that they had obtained a mixture of zeolite Ω and other substances. Since then, several methods for producing zeolite using organic nitrogen compounds have been invented, but it has been found that the zeolites obtained differ depending on the type of organic nitrogen compound used, the composition ratio of the raw materials used, and the hydrothermal treatment conditions. For example, benzyltrimethylammonium salt uses erionite zeolite, tetramethylammonium hydroxide uses mordenite or ZSM-8 zeolite depending on the conditions, and tetramethylammonium compounds use erionite zeolite.
ZSM-4 can be produced, and ZSM-5 can be produced using a tetrapropylammonium compound. Of these, zeolite synthesized using an organic nitrogen compound containing a quaternary ammonium cation as described above is called ZSM zeolite by Mobil Oil. Up to 34 types have been identified. Many of the ZSM series zeolites have similar structures, but the fundamentally important ones are
This zeolite is called ZSM-5, and its structure consists of a 10-membered oxygen ring, and its pores are approximately 5 Å smaller than those of small-pore zeolites such as erionite, offretite, and A zeolite, which are 8-membered oxygen ring zeolites. X and Y, which are 12-membered oxygen ring type zeolites
It is located in the middle of about 10 Å of zeolite, and the long axis is about 6
It is believed that it has an elliptical shape with a diameter of about 9 Å and a minor axis of about 5 Å. Therefore, Y zeolite can adsorb not only straight chain hydrocarbons with a molecular size of 5 Å or less, but also slightly branched hydrocarbons, but Y zeolite can adsorb large molecular sizes of 2 to 3 or more side chains. It exhibits unique shape selectivity that prevents it from adsorbing hydrocarbons. Therefore, if this zeolite is used as a catalyst, in addition to conversion reactions such as decomposition, isomerization, alkylation, and disproportionation that are active with ordinary zeolite catalysts, it can also selectively decompose wax content in hydrocarbon oil. It has a wide range of uses, including catalytic dewaxing reactions, such as dehydration of alcohols, and use as a catalyst for the production of olefins and aromatic compounds from oxygen-containing compounds such as methanol. ZSM−
As mentioned above, zeolite has excellent performance as a conversion reaction catalyst, but the quaternary organic nitrogen compound used as one of the reaction mixtures is extremely expensive, resulting in an expensive product. There is. Recently, as an alternative inexpensive organic nitrogen compound, ZSM- 5
A method of producing zeolite has been proposed. The inventor has made various studies and efforts to find a new method for producing zeolite that is industrially inexpensive and catalytically active, and has developed a method for producing zeolite that is inexpensive and easily available industrially as an absorbent for hydrogen sulfide. We discovered that it is possible to produce a new zeolite with high purity, which has a structure similar to ZSM-5 that includes diglycolamine cations and catalytic performance, by using diglycolamine as an organic nitrogen compound. Achieved invention. That is, the present invention provides a synthetic crystalline aluminosilicate, which is characterized in that a raw material mixture containing a silica source, an alumina source, an alkali metal source, water, and diglycolamine is placed under temperature and pressure conditions that produce crystalline aluminosilicate. The invention consists in a method of producing zeolite. Next, a method for producing zeolite according to the present invention and a conversion reaction using the same as a catalyst will be explained.
As the silica source, those commonly used in the synthesis of zeolites such as silica, silica sol, silica gel, sodium silicate and silicic acid can be used, and colloidal silica is preferred. As the alumina source, alumina gel, alumina sol, alumina, sodium aluminate, aluminum sulfate, etc. can be used, but water-soluble sodium aluminate is suitable for handling. Diglycolamine used as an organic nitrogen compound is formally known as 2-(2-aminoethoxy)ethanol,
It is a primary amine with the molecular formula of NH ₂ CH ₂ CH ₂ OCH ₂ CH ₂ OH, and is distinguished from alcohol amines because it has an ether structure. In addition, of course, precursors that produce diglycolamine can be used. As the alkali metal, sodium is usually used, and one or more sodium sources selected from sodium hydroxide, sodium silicate, and sodium aluminate can be used. Next, the composition ratios of these starting materials are prepared as follows (molar ratio).

[Table] (Here, OH ^- is due to diglycolamine.
OH ^- shall not be included, and RN ⁺ indicates a diglycolamino cation. ) This mixture is usually heated at 80-200℃, preferably 120-200℃.
Heat in a closed container at a temperature of 170°C for approximately 0.5 to 30 days. After the reaction is completed, the resulting crystalline product is filtered, washed with water to remove excess alkali, and then dried. The zeolite obtained in the present invention contains the cations of diglycolamine used as a reaction raw material even after sufficient water washing, and these are thought to be coordinated within the structure in the same way as the included sodium ions. Conceivable. Moreover, its structure is the same as long as it is synthesized using diglycolamine and at the above-mentioned composition ratio, and it can be distinguished from other zeolites by its X-ray diffraction image. Table 1 shows the X-ray diffraction grating data of the zeolite obtained when the zeolite was prepared with a SiO ₂ /Al ₂ O ₃ ratio of 70. The diffraction data in Table 1 were obtained by standard X-ray diffraction techniques with irradiation of a K-alpha doublet of copper and were recorded on a recorder as a function of peak heights I and 2θ, where θ is the Bragg angle. Ru. I/I ₀ is a relative intensity, and is a relative value when 2θ=23.2, which shows the strongest peak, is taken as 100. The zeolites produced according to the invention can be used as conversion catalysts either as such or by mixing with other support materials such as alumina, silica, silica-alumina. Furthermore, the organic cations present in the synthesis state are heated at a temperature in the range of 400 to 800°C to decompose, and the alkali metals present are exchanged with one or more other cations using known methods. A more preferred catalyst is then prepared. Typical cations include hydrogen ions in group _A of the periodic table or ammonium ions, which are its precursors.
Group _A magnesium, calcium, barium, _B
The cations are group zinc, cadmium, group _A tin, lead, group _B chromium, group iron, cobalt, nickel, palladium, platinum and rare earths as well as mixtures thereof. The zeolite produced in this way, like other zeolite catalysts, has active sites based on the hydrogenation-dehydrogenation activity of metal cations exchanged with those due to the solid acidity of the zeolite. It can be used in hydrocarbon conversion reactions such as decomposition, isomerization, alkylation, and disproportionation in which catalysts are usually used, and is also effective in catalytic dewaxing reactions that selectively decompose wax components due to the shape selectivity of this zeolite. It is. Furthermore, this catalyst has a high silica to alumina ratio of 20 or more, so it is hydrophobic, and can also be used as a catalyst for dehydrating alcohols and producing olefins or aromatics from oxygen-containing compounds such as alcohols. EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following unless it exceeds the gist thereof. Example 1 436.6 ml of colloidal silica (containing 23.3 g of silica in 100 ml), 275 ml of water, and diglycolamine
63.6g was added and stirred. Here, add 4.485 g of sodium aluminate and sodium hydroxide to 100 ml of water.
Add a solution containing 13.648g and stir for 30 minutes. The resulting gel mixture prepared at a silica/alumina ratio of 70 was placed in a stainless steel pressure vessel with an internal volume of 2.
Heated at 160°C for 7 days. The obtained crystalline product was washed with water in step 2, dried at 130℃, and weighed.
It was 86g. The chemical analysis results of this crystalline substance are shown in Table 2.
However, it gave nitrogen and carbon equivalent to diglycolamine, and the silica/alumina ratio was 30.0. According to X-ray diffraction analysis, the diffraction pattern is shown in Table 1.
No other foreign zeolite was observed, and the zeolite was 100% pure and contained diglycolamino cations. Example 2 Zeolite was produced in the same manner as in Example 1, except that the silica/alumina ratio was adjusted to 29. 77g of zeolite with a silica-alumina ratio of 25 was synthesized, and its X-ray diffraction pattern was consistent with Table 1, and no other impurities were observed. Example 3 50 g of the zeolite produced in Example 1 was heated with a 5N ammonium chloride aqueous solution at 100°C for 3 hours in a glass flask equipped with a condenser, and after cooling, the ammonium chloride aqueous solution was added again and the same operation was repeated three times. Alkali metals in zeolite were removed by replacing them with ammonium ions. After that, wash thoroughly with water until no chlorine ions are detected in the solution.
It was dried at 130°C and calcined at 550°C for 3 hours to convert ammonium ions into hydrogen ions and decompose organic nitrogen cations in the zeolite into hydrogen ions. The obtained H-type zeolite was molded using a tablet molding machine, the particle size was made uniform to 12 to 32 meshes, and the mixture was subjected to a conversion reaction of _C6 hydrocarbons. Raw material oil is 2.2-dimethylbutane 32.02 mol%, 2-methylpentane
It is a _C6 hydrocarbon mixed oil with different molecular sizes containing 34.35 mol% and 32.83 mol of n-hexane.The reaction conditions were a temperature of 290℃, a pressure of 25Kg/ ^cm2 gauge,
LHSV 1.5h ^-1 and hydrogen to hydrocarbon molar ratio of 7 were used. As shown in Table 3, the reaction products include decomposition products from methane to pentane, as well as paraffins, naphthenes, and aromatics with carbon atoms of 7 to 9, which are not present in the feedstock oil. This shows that this catalyst has reaction activities for decomposition, isomerization, alkylation, and aromatization. Furthermore, the reactivity is highest with n-hexane, which has the smallest molecular size, followed by methylpentane, which has one methyl group, and 2,2-dimethylpentane, which has two methyl groups, does not react at all. In catalysts prepared from mordenite or Y zeolite with a pore diameter of 9 Å or more, the reactivity of 2,2-dimethylbutane, which has tertiary carbon and which normally tends to generate carbonium ions, is the highest, and therefore the present invention It can be easily inferred that the reactivity of the zeolite exhibits shape selectivity resulting from the fact that the pore size of the zeolite is large enough to contain n-paraffin and one methyl group. Example 4 The H-type zeolite prepared in Example 3 was subjected to a methanol conversion reaction. The reaction conditions were a temperature of 310℃;
The pressure was normal pressure LHSV = 1.5 h ^-1 , and the reaction was carried out in a nitrogen atmosphere. The results are shown in Table 4. At 310°C, 100% of methanol is converted to water and hydrocarbons, and the products are hydrocarbons with up to 10 carbon atoms.
The C ₅ ⁺ fraction contained 69.6% by weight of aromatics, 5.0% by weight of naphthenes, 1.2% by weight of olefins, and 23.9% by weight of paraffins.

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Claims (1)

[Claims] 1. Synthetic crystalline aluminosilicate, characterized in that a raw material mixture containing a silica source, an alumina source, an alkali metal source, water and diglycolamine is placed under temperature and pressure conditions that produce crystalline aluminosilicate. A method of producing silicate zeolite. 2 The crystalline aluminosilicate zeolite obtained by heating the raw material mixture under pressure is then added to the periodic table.
A method for producing a synthetic crystalline aluminosilicate zeolite according to claim 1, which comprises ion exchange with one or more cations belonging to the group _A , _A , _B , _A , _B , and rare earths.