JPS6159246B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing crystalline aluminosilicate zeolite. More specifically, the present invention relates to a method for producing crystalline aluminosilicate zeolite in which seed crystals are present in a raw material mixture consisting of silica, alumina, an alkali metal, and water. Crystalline zeolites, whether natural or synthetic, contain cations such as Na, K or H ions. These zeolites are SiO ₄
It has a three-dimensional network structure of SiO ₄ and AO ₄ , and has a characteristic of having a highly ordered tetrahedral structure in which SiO 4 and AO ₄ are cross-linked through oxygen atoms. Such crystalline zeolites have many small pores within their crystal structure and are well known as molecular sieves.
Taking advantage of this characteristic, it is used for various purposes. This crystalline zeolite is not only used in conversion reactions of various hydrocarbons, but also recently it has been used as a catalyst for producing hydrocarbons from synthesis gas via methanol and dimethyl ether.
Methods for producing ZSM-5 or similar zeolites are well known. The method for manufacturing these zeolites uses silica,
The most well-known method is to carry out the reaction by adding tetraalkylammonium ions to a raw material composition consisting of alumina, an alkali metal, and water. However, this method of adding tetraalkylammonium ions has the drawback of being expensive, and is not necessarily suitable as an industrial production method. It has been proposed to use alkylamines, amino alcohols, ammonia, organic sulfur compounds, etc. as additives to overcome this drawback. On the other hand,
A method for producing zeolite that does not require ion exchange treatment from a raw material composition (in the absence of an alkali metal) consisting of silica, metal oxides/hydroxides, water, and hexamethylene diamine has also been proposed. However, since all conventional methods use organic compounds, they are expensive and are not necessarily suitable from an industrial production standpoint. Furthermore, it has the disadvantage that the organic compound used must be removed by firing. The present inventors have conducted extensive research into methods for producing crystalline aluminosilicate zeolite in order to resolve the shortcomings of conventional methods. It has been found that crystalline zeolite can be obtained by adding seed crystals instead of adding tetraalkylammonium salts, amines, etc. Moreover, it was revealed that the X-ray diffraction pattern of the obtained reaction product was similar to that of the above-mentioned known zeolite ZSM-5. This fact was truly surprising. The present invention has been made based on this knowledge. That is, the present invention uses silica, alumina,
When maintaining a raw material mixture consisting of an alkali metal and water under the temperature and time conditions required to produce crystalline aluminosilicate zeolite, crystalline zeolite powder is present in the raw material mixture and the pH of the reaction system is adjusted to 9. This is a method for producing crystalline aluminosilicate zeolite, which is characterized by maintaining the crystalline aluminosilicate zeolite at a temperature of ~12. The X-ray diffraction pattern of the crystalline zeolite powder produced by the method of the present invention was very similar to that of the conventionally known zeolite ZSM-5. Therefore, it can be suitably used in organic compound conversion methods, for example, conversion reactions of hydrocarbon compounds and oxygen-containing compounds such as methanol. The synthesis reaction of the present invention can use a raw material mixture consisting of a silica source, an alumina source, an alkali metal, and water that are used in the synthesis of ordinary crystalline zeolites. This is carried out by adding crystalline zeolite powder to these mixtures and maintaining the pH of the reaction system between 9 and 12. The silica source is not particularly limited as long as it is commonly used in the production of crystalline zeolite, and examples include silica powder, silicic acid, colloidal silica, and dissolved silica. Dissolved silica is Na ₂ O or
Examples include water glass silicates and alkali metal silicates containing 1 to 5 moles of SiO ₂ per mole of K ₂ O. In addition, the alumina source is not particularly limited as long as it is commonly used in the production of crystalline zeolite, and aluminum salts such as sulfates and nitrates, such as aluminum sulfate, sodium aluminate, colloidal alumina, alumina, etc. used. The ratio of silica to alumina in the raw material mixture of the present invention is desirably in the range of 10 to 500, preferably 20 to 200 in terms of SiO ₂ /A ₂ O ₃ molar ratio. On the other hand, sodium hydroxide, potassium hydroxide, etc. are used as the alkali metal source. moreover,
Sodium silicate or sodium aluminate can also serve as a source of silica or alumina. Particularly preferred as the alkali metal is sodium, and this alkali metal is used in an amount of 0.01 to 50 mol, preferably 0.1 to 10 mol, per 1 mol of silica ( _SiO2 ) as _M2O . Next, as the crystalline zeolite as a seed crystal, zeolite ZSM-5, A-type zeolite, Y
There are powders such as type zeolite, X type zeolite, and mordenite. Among these, especially zeolite
ZSM-5 type materials are preferably used. The amount of this seed crystal is not particularly limited, but it is usually added in an amount of 0.01 to 8% by weight, preferably 0.05 to 4.0% by weight, based on the silica (SiO ₂ ) in the raw material. In the present invention, a raw material mixture consisting of silica, alumina, an alkali metal, water, and crystalline zeolite powder may be heated at a temperature and for a time necessary to produce crystalline aluminosilicate zeolite. Note that the amount of water is not particularly limited in the present invention. Moreover, at this time, a mineralizing agent can be added to promote crystallization if necessary. Furthermore, in the production method of the present invention, it is necessary to adjust the pH of the reaction system, and the pH is adjusted to a range of 9 to 12. If the pH is outside this range, crystalline zeolite cannot be obtained. In the present invention, PH
It is more preferable to adjust the value to 9.5 to 11, and a good crystalline zeolite can be obtained. The synthesis reaction of the present invention is carried out by heating the raw material mixture at a temperature and time necessary to produce crystalline zeolite, and the reaction temperature is 80°C.
~300℃, preferably in the range of 120-200℃,
The reaction time is 0.5 hours to 30 days, preferably 5 hours to 10 days. There are no particular restrictions on the pressure, and it is usually carried out under autogenous pressure. Further, the reaction system is usually kept under stirring, and the atmosphere may be replaced with an inert gas if necessary. The synthesis reaction is continued until sufficient crystalline zeolite is produced by heating the raw material mixture to a desired temperature. After the reaction mixture in which the production of crystalline zeolite has been completed is cooled to room temperature, the crystals are separated by filtration, decantation, centrifugation, etc., and thoroughly washed with water to obtain crystals. Crystalline aluminosilicate zeolite can be obtained by drying these crystals usually at 100°C or higher for several hours. The present invention involves activating this crystalline zeolite by calcining it in air at a temperature in the range of 300 to 700°C for about 2 to 48 hours before using it as a catalyst, or by activating the crystalline zeolite by activating the alkali metal ions present in the crystalline zeolite. This method includes a method of ion-exchanging part or all of the cation with at least one other cation to obtain H-type crystalline zeolite. This ion exchange method is a well-known technology in the industry.
Suitable cations include metal ions, ammonium ions, hydrogen ions, and mixtures thereof; examples of metal ions include cations of lithium, silver, magnesium, calcium, barium, aluminum, manganese, cobalt, nickel, or rare earth metals. be able to. These selections are arbitrarily determined depending on the type of conversion reaction. In the ion exchange method, the crystalline zeolite may be contacted with an aqueous solution containing a desired cation, and chlorides, nitrates, and sulfates of cations are usually used. After ion exchange, the crystalline zeolite is washed with water, dried, and then calcined in air or inert gas at a temperature of 300 to 700°C for 2 to 48 hours or more to become a catalytically active catalyst. . The crystalline zeolite obtained by the method of the invention is of the same type as zeolite ZSM-5 and can be used in conversion reactions of organic compounds, such as hydrocarbon compounds and oxygenated compounds such as methanol. Such methods include alkylation of aromatic compounds with olefins; aromatization of olefins and paraffins; isomerization of aromatics, paraffins, and olefins; disproportionation of aromatics; oligomerization of olefins; and cracking. Further examples include methods for producing hydrocarbons from synthesis gas and methanol. As detailed above, the method of the present invention relates to an inexpensive and industrially advantageous method for producing crystalline zeolite that does not use any organic compounds, and can be used as a catalyst or catalyst carrier for the various conversion reactions described above. This has made it possible to provide crystalline zeolites which are suitable for use in a number of other applications, such as adsorbents, extractants, ion exchangers, molecular sieves, etc. The method of the present invention will be explained below with reference to Examples. Example 1 A solution containing 7.52 g of aluminum sulfate (18 hydrate), 17.6 g of sulfuric acid (9.7%), and 250 ml of water was prepared as A.
Make it into a liquid. Water glass (SiO ₂ 37.6% by weight,
(Na ₂ O 17.5% by weight, water 44.9% by weight) 162g, water 300ml
The solution made from this is called Solution B. sodium chloride
A solution of 79 g and 122 ml of water is called Solution C.
While stirring Solution C, Solutions A and B were gradually added dropwise to it at room temperature. After adding 1 g of crystalline aluminosilicate zeolite powder (obtained by adding 25 g of tetrapropylammonium bromide as an organic compound to the above raw material compound and carrying out the same reaction) to this mixture, the pH was adjusted to 10.0. The mixture was placed in an autoclave No. 1 and reacted for 20 hours at 170° C. under autogenous pressure while stirring at a rotation speed of 200 rpm.
After the reaction mixture was cooled, it was washed five times with 1 portion of water. Next, the solid content was separated by filtration and heated at 120℃.
After drying for 3 hours, 40.5 g of crystalline aluminosilicate zeolite was obtained. Note that this product contained some crystalline sodium silicate. Table 1 shows the results of the X-ray diffraction pattern of this crystalline aluminosilicate zeolite. This zeolite has the following composition in terms of molar ratio. _{0.9Na2O : 60SiO2} : _1.0A2O3

【table】

[Table] Example 2 The procedure of Example 1 was followed except that 11.3 g of aluminum sulfate (18 hydrate) was used to obtain 53.8 g of crystalline aluminosilicate zeolite. The results of the X-ray diffraction pattern were the same as in Table 1. Example 3 Aluminum sulfate (18 hydrate) 18.8 g, sulfuric acid (97
%) 17.6g and 250ml of water as a solution A
Make it into a liquid. Water glass (SiO ₂ 37.6% by weight,
(Na ₂ O 17.5% by weight, water 44.9% by weight) 162g, water 300ml
The solution obtained is called Solution B. sodium chloride
A solution of 79 g and 122 ml of water is called Solution C.
While stirring Solution C, Solutions A and B were gradually added dropwise to it at room temperature. After adding 1 g of mordenite powder to this raw material mixture, the pH was adjusted to 10.0, and the
The mixture was placed in an autoclave and reacted for 20 hours at 170°C under autogenous pressure while stirring at 200 rpm. After the reaction mixture was cooled, it was washed five times with 1 portion of water. Then, the solid content is separated by filtration,
After drying at 120° C. for 3 hours, 55 g of crystalline aluminosilicate zeolite was obtained. In addition, this material contained some mordenite. The results of the X-ray diffraction pattern of this crystalline aluminosilicate zeolite were the same as those shown in Table 1. Note that this zeolite has the following composition in terms of molar ratio. 0.9 (Na ₂ O): 29 (SiO ₂ ): 1.0 (A ₂ O ₃ ) Example 4 In Example 3, silicalite (crystalline silica described in US Pat. No. 4,061,724) was used instead of mordenite. The procedure of Example 3 was followed except that 54 g of crystalline aluminosilicate zeolite was obtained. Note that this product contained some crystalline sodium silicate. The results of the X-ray diffraction pattern of this crystalline aluminosilicate zeolite were the same as those shown in Table 1. Note that this zeolite has the following composition in terms of molar ratio. 0.9( _Na2O ):29( _SiO2 ): _1.0 ( _A2O3 ).

Claims (1)

[Claims] 1. When a raw material mixture consisting of silica, alumina, alkali metal, and water is maintained under the temperature and time conditions necessary to produce crystalline aluminosilicate zeolite, crystalline zeolite powder is added to the raw material mixture. 1. A method for producing crystalline aluminosilicate zeolite, which comprises maintaining the pH of the reaction system at 9 to 12. 2. The manufacturing method according to claim 1, wherein the crystalline zeolite powder is present in an amount of 0.01 to 8% by weight based on the raw material silica (SiO ₂ ). 3. The manufacturing method according to claim 1, wherein the reaction system has a pH of 9.5 to 11.