JPS636487B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing phasiasite-type zeolite with a SiO ₂ /Al ₂ O ₃ molar ratio of 4 or more, in which most of the silica source for the zeolite is derived from alkali silicate, and the remainder is derived from silica gel. The present invention relates to a method for economically producing the above-mentioned faujasite type zeolite. Faujasite-type zeolite with a high SiO ₂ /Al ₂ O ₃ molar ratio (hereinafter referred to as high-silica phodiasite) is thermally stable compared to zeolite with a low molar ratio, so it is a catalyst component. It also has important uses as an adsorbent. Many methods have been proposed for producing high-silica phoriasite, and a typical example is a method using silica sol or silica gel, sodium aluminate, and sodium hydroxide as raw materials.
However, this method requires expensive silica sol or silica gel as the silica source for the zeolite, and has the disadvantage that high-silica phoriasite cannot be produced at low cost. Under these circumstances, the prior art has proposed a method for producing high-silica phoriasite at low cost by searching for alkali silicate or other sources as the main source of silica. For example, in Japanese Patent Publication No. 49-13720, a crystal nucleus liquid consisting of hydrated silica, sodium aluminate and caustic soda is prepared, and this crystal nucleus liquid is added to a gel obtained from an aqueous mixture consisting of sodium silicate and sodium aluminate. However, a method for producing high-silica phoriasite by crystal growth is described. Similarly, JP-A-52-94899 discloses that the main source of silica _is sodium _silicate or _metakaolin ,
A slurry with a nucleation center having a molar composition of 19SiO ₂ 220~900H ₂ O and 1.2~3Na ₂ O 4~
A method is described in which zeolite synthesis mixtures with molar compositions of 7SiO ₂・Al ₂ O ₃・40 to 200H ₂ O are prepared, and a small proportion of the former is mixed with the latter to crystallize high-silica foresiasite. ing. In this method, the amount of Na ₂ O in the zeolite synthesis mixture described above is lower than usual in order to reduce the manufacturing cost of high-silica phoriasite, and the delay in crystallization rate caused by this is suppressed by reducing the amount of nucleation centers described above. This is nothing but compensation by mixing a relatively large amount of slurry. However, with this method, only zeolite with a small crystallite size can be obtained. Generally, the crystallite diameter of synthetic zeolite is determined from the half-width of the X-ray diffraction peak by Warren [J.Appl.Phys., 12 375
('41)] or Jones [Proc.Roy.Soc.A 166 376 ('
38)], and in general, those with a wide half-width have a small crystallite diameter.
Regarding the high silica phoriasite produced by the method of Publication No. 94899, although the zeolite content determined by the adsorption capacity and the height of the X-ray diffraction peak is sufficient, the half-width of the peak is wide; The crystal grain size is small. As is well known, zeolite with a small crystallite diameter is inferior in heat resistance to high silica phoriasite, so this type of zeolite is used in FCC, which has a high operating temperature.
When used as a carrier for catalysts or hydrocracking catalysts, a long life cannot be expected. Incidentally, according to the findings obtained by the present inventors, the crystallite diameter
Zeolite with a diameter of 1000 Å or less has low heat resistance, and when used as a catalyst or catalyst carrier, there is a significant decrease in activity due to thermal deterioration. On the other hand, the crystallite diameter
Zeolite of 1400Å or more shows sufficient heat resistance,
Therefore, it exhibits high activity even when used as an FCC catalyst. Thus, the present invention provides a method for economically producing high silica phoriasite with a crystallite diameter of 1400 Å or more using sodium silicate as the primary source of SiO ₂ . That is, the method of the present invention uses (a) silica sol, sodium aluminate, and sodium hydroxide as raw materials, and _{uses 2 to 3.4Na2O.Al2O3.6} to 9SiO2.90
A first aqueous mixture represented by a molar composition formula of ~120H ₂ O is prepared, this mixture is aged under conditions that do not cause crystallization, and (b) sodium silicate, sodium aluminate, and mineral acid are used as raw materials, and 2. ~
4Na ₂ O・Al ₂ O ₃・6～9SiO ₂・90～150H ₂ O・0.5
A second aqueous mixture represented by a molar composition formula of ~2.5Na ₂ The second aqueous mixture is mixed at a weight ratio of 3:97 to 30:70, and the mixture is heated at a temperature at which crystallization occurs for a time sufficient for crystallization. This method makes it possible to produce a phaujasite-type zeolite having a SiO ₂ /Al ₂ O ₃ molar ratio of 4 or more and a crystallite diameter of 1400 Å or more. The first aqueous mixture of the present invention is prepared using silica sol, sodium aluminate, and sodium hydroxide as raw materials, and the molar composition of this mixture is 2
~ _3.4Na2O・_{Al2O3 ・}6~ _9SiO2・90~ _120H2O ,
Preferably ₂ ~3Na2O・_Al2O3・7 _{~ 9SiO2}・90
~110H ₂ O, which is not substantially different from the molar composition of the reaction mixture for synthesis of faujasite type zeolite described in Japanese Patent Publication No. 42-8527. Therefore, it is possible to produce zeolite only from the first aqueous mixture, but in the present invention, in order to reduce production costs and obtain zeolite with a large crystallite size, the first aqueous mixture is 2 Used in combination with an aqueous mixture. Prior to mixing with the second aqueous mixture, the first aqueous mixture of the present invention must be thermally formed under conditions in which crystallization does not occur. This is because if this ripening is neglected, the zeolite content in the product will decrease, as is clear from the Examples below. Aging is performed by heating the first aqueous mixture at a temperature below 80°C, preferably below 40°C.
Stir for more than 10 hours or at a temperature of 80 to 110℃.
This is carried out by stirring for 10 hours, particularly preferably by stirring the first aqueous mixture at a temperature below 80°C, preferably below 40°C, for at least 15 hours, followed by stirring at 80-110°C.
Stir at a temperature of 3 to 8 hours. When performing heating aging, if the aging time is too long, crystallization will occur in the first aqueous mixture and zeolite will be produced, so heating aging can be carried out within the above-mentioned time range. Note that even if the first aqueous mixture in which crystals have formed is mixed with the second aqueous mixture to further advance crystallization, zeolite with a large crystallite size cannot be obtained. The second aqueous mixture of the present invention comprises sodium silicate,
It is prepared using sodium aluminate and mineral acid as raw materials, and its molar composition is 2~ _4Na2O・_Al2O3・₆ ~
_9SiO2・90~ _150H2O・0.5~ _2.5Na2X (However, X is an acid group of a mineral acid represented by divalent, e.g.
SO ₄ ^-- , Cl ₂ ^-- , (NO ₃ ) ₂ ^--, etc.). When preparing the second aqueous mixture, it is possible to add mineral acid to sodium silicate to form a gel, and then add sodium aluminate thereto, or to mix sodium aluminate and sodium silicate, and then add it to the gel. Mineral acids can also be added. The second aqueous mixture obtained by the former preparation method is
The second aqueous mixture obtained by the latter method of preparation is suitable for mixing with the first aqueous mixture which has undergone warm aging. For sodium silicate as a raw material, sodium silicate of any silicate ratio can be used, but the salt produced by reaction with mineral acid (in the above molar composition formula)
In order not to increase the amount of Na2X (equivalent to _Na2X ),
It is preferable to use sodium silicate having a small molar ratio of Na ₂ O to SiO ₂ , and in this sense commercially available No. 3 silica can be said to be a suitable raw material. Further, as the mineral acid, any of sulfuric acid, hydrochloric acid, and nitric acid can be used. However, considering the material of the preparation container and the cost of raw materials, it is most preferable to use sulfuric acid. In this case, the sulfuric acid may be either concentrated sulfuric acid or diluted sulfuric acid. Note that when aluminum sulfate is used instead of sulfuric acid, the second aqueous mixture contains
Since SO ₄ ^-- and Al will be supplied at the same time,
The amount of sodium aluminate used, which is a source of Al ₂ O ₃ , can be reduced. In the present invention, it is extremely important to include acid groups of mineral acids in the second aqueous mixture. This acid group reacts with a portion of sodium to form a kind of salt, and it is presumed that this salt contributes to the growth of zeolite crystallites. Although the second aqueous mixture can be mixed with the first aqueous mixture without aging, it is preferable to stir the mixture at room temperature for 10 to 30 hours. This is because by carrying out this aging, even if a lumpy gel is generated during the preparation stage of the second aqueous mixture, it can be digested and pulverized. The second aqueous mixture and the aged first aqueous mixture are
The latter and the former are mixed in a weight ratio of 3:97 to 30:70. If the amount of the first aqueous mixture is less than 3% by weight of the total, the zeolite cannot be crystallized, and conversely, if the amount of the first aqueous mixture is more than 30% by weight, although crystallization is possible, the silica of the zeolite Since silica sol is required as a source, zeolite must be expensive. The reaction mixture obtained by combining the second aqueous mixture and the aged first aqueous mixture is heated to a temperature and time sufficient to cause crystallization by methods well known in the art. Generally at a temperature of 80-110℃
It is preferable to heat while stirring for about 16 to 48 hours. In the present invention, it is possible to gradually crystallize zeolite and grow crystallites, so if the heating time is less than 16 hours, the zeolite content in the product will be low. However, heating for more than 48 hours has no practical meaning since the formation of zeolite and the growth of crystallites have already been completed. The present invention will now be described in more detail with reference to Examples, but these Examples are not intended to limit the present invention. Note that all percentages in the following description are based on weight. Example 1 A room temperature sodium aluminate solution (Al ₂ O ₃ 22%,
Add 1,123 g of caustic soda solution (NaOH 47%) to 2,782 g of Na ₂ O (17.4%), then add 1,248 ml of water, and add an additional 30% while stirring.
9,600 g of a silica sol solution of SiO ₂ was added over 3 minutes to form a gel, thereby obtaining a slurry-like first aqueous mixture at a temperature of 17°C. _The molar composition _of this _{aqueous mixture} was _{2.4Na2O.Al2O3.8SiO2.96H2O} . Next, this is aged under the conditions shown in the table below.
A total of three first aqueous mixtures were obtained.

[Table] Meanwhile, add 8 kg of sodium silicate solution (SiO ₂ 24%, Na ₂ O 7.56%) to a 2-volume kneader, and add 206 ml of water.
Add 98% concentrated sulfuric acid while stirring.
Added 536g. The addition of sulfuric acid produced a rigid gel, which was broken up into small pieces by continued stirring. Next, 1854 g of previously prepared sodium aluminate solution (22% Al ₂ O ₃ , 17.4% Na _{2 O} ) was mixed with the above material in the kneader for a sufficient time (about 60 minutes) to form a slurry. _A second aqueous mixture was prepared by stirring _to have _{a molar composition of 2.4Na2O.Al2O3.8SiO2.96H2O.1.34Na2SO4} . This was treated as shown in the table below to obtain two types of second aqueous mixtures.

[Table] Next, three types of first aqueous mixtures and two types of second aqueous mixtures were mixed in the combinations shown in Table 3, and each of the resulting reaction mixtures was first stirred at room temperature for 60 minutes, then at 95°C. The mixture was stirred at a temperature of 48 hours to form crystals. Thereafter, the product is filtered from the mother liquor,
The product was analyzed after washing. The results are shown in Table 3. Incidentally, all the products were faujasite type zeolites.

[Table] No. 3 in Table 3 shows that even if the amount of the first aqueous mixture used is as small as 5% of the total, according to the present invention, a faujasite type zeolite can be obtained as desired. Also, from the comparison between No. 5 and No. 6,
Before mixing the first aqueous mixture and the second aqueous mixture, the first aqueous mixture must be aged to some extent, and it is understood that stirring at room temperature for 10 hours is sufficient for the aging. Example 2 Sodium silicate solution (SiO ₂ 24%, Na ₂ O 7.56%)
3 kg of water, 796 ml of water, 226 g of concentrated sulfuric acid (98%) and sodium aluminate solution (Al ₂ O ₃ 22%, Na ₂ O 17.4
A second aqueous mixture having a molar composition of 2.0Na ₂ O・Al ₂ O ₃・6SiO ₂・96H ₂ O・1.13Na ₂ SO ₄ was prepared in exactly the same manner as in Example 1, except that 927 g of %) was used. did. After stirring this at room temperature for 24 hours, 850 g thereof was mixed with 150 g of the first aqueous mixture C of the example, and this mixture was treated under the same conditions as in the example to obtain a product. Next, the product was analyzed in the same manner as in the example, and it was found that the product was a phaujasite-type zeolite with a SiO ₂ /Al ₂ O ₃ molar ratio of 4.3, zeolite content = 102%, and crystallite diameter = 1700 Å. Ta. Example 3 Sodium silicate solution (SiO ₂ 29%, Na ₂ O 9.14%)
3724g of water, 541ml of water, 249g of concentrated sulfuric acid (98%) and sodium aluminate solution (Al ₂ O ₃ 22%,
The same procedure was used as in Example 1, except that 927 g of Na _{2 O} (17.4%) was used, and 2.8Na ₂ O・Al ₂ O ₃・9SiO 2 ・96H _{2 O}・1.24H ₂ SO ₄ A two-aqueous mixture was prepared. 850 g of this second aqueous mixture was mixed with 150 g of the first aqueous mixture C of Example 1, and this mixture was treated under the same conditions as in Example 1 to obtain a product. This product is
SiO ₂ /Al ₂ O ₃ molar ratio = 4.76, zeolite content =
It was 100% faujasite type zeolite with a crystallite diameter of approximately 1700 Å. Example 4 After adding 153 g of 47% caustic soda solution and 230 ml of water to 464 g of sodium aluminate solution (Na ₂ O ₃ 22%, Na ₂ O 17.4%) prepared in advance, 30% sodium hydroxide solution was added to this while stirring. 1600 g of silica sol solution was added over 3 minutes to form a gel, thereby preparing a slurry-like first aqueous mixture at a temperature of 23°C. _The molar composition _of this _{aqueous mixture} was _{2.2Na2O.Al2O3.8SiO2.96H2O} . Next, add the above first aqueous mixture at room temperature for 24 hours.
After stirring and aging for a period of time, 150g of it was added to Example 1.
850 g of the second aqueous mixture Y were mixed and the reaction mixture was stirred at a temperature of 95° C. for 72 hours to form crystals. The product was filtered and analyzed after washing.
This product was a faujasite type zeolite with a SiO ₂ /Al ₂ O ₃ molar ratio = 5.02, zeolite content = 91%, and crystallite diameter = 1800 Å. Example 5 Using caustic soda solution (47%) and water, respectively
A slurry-like first aqueous mixture having the following molar composition and a temperature of 20° C. was prepared in exactly the same manner as in Example 4 except that the amounts were changed to 221 g and 726 ml. 2.6Na ₂ O・Al ₂ O ₃・8SiO ₂・126H ₂ O After stirring and aging this first aqueous mixture at room temperature for 24 hours, 150 g of it was mixed with 850 g of the second aqueous mixture Y of Example 1. The reaction mixture was stirred at a temperature of 95° C. for 24 hours to form crystals. When the product was filtered and washed and analyzed, the product was found to be
SiO ₂ /Al ₂ O ₃ = 4.53, zeolite content = 102%,
It was a faujasite type zeolite with a crystallite diameter of 1500 Å. Example 6 The amounts of caustic soda solution (47%), water and silica sol solution (SiO30%) used were 182g and 493ml, respectively.
A slurry-like first aqueous mixture having the following molar composition and a temperature of 19° C. was prepared in exactly the same manner as in Example 4 except that the amount was changed to 1200 g. 2.4Na ₂ O・Al ₂ O ₃・6SiO ₂・96H ₂ O After stirring and aging this first aqueous mixture at room temperature for 24 hours, 150 g of it was mixed with 850 g of the second aqueous mixture Y of Example 1. The reaction mixture was stirred at a temperature of 95° C. for 48 hours to form crystals. When the product was filtered and washed and analyzed, the product was found to be
SiO ₂ /Al ₂ O ₃ = 4.71, zeolite content = 101%,
It was a faujasite type zeolite with a crystallite diameter of 1600 Å. Example 7 After adding 204 g of 47% caustic soda solution and 269 ml of water to 464 g of sodium aluminate solution (22% Al ₂ O ₃ , 17.4% Na ₂ O) prepared in advance, 30% sodium hydroxide solution was added to this while stirring. 1600 g of silica sol liquid was added over 3 minutes to prepare a slurry-like first aqueous mixture at a temperature of 24°C. _The molar composition _of this aqueous _{mixture was 2.5Na2O.Al2O3.8SiO2.100H2O} . Next, this is aged under the conditions shown in the table below.
A total of three first aqueous mixtures were obtained.

[Table] * No zeolite crystals were observed by X-rays.On the other hand, sodium aluminate solution (Al ₂ O ₃ 22%,
Add 524 ml of water to 464 g of Na ₂ O (17.4%), and add sodium silicate solution (SiO24%,
Add 2000 g of Na ₂ O (7.56%) over about 5 minutes, and then add 525 g of 25% dilute sulfuric acid to make 2.4Na ₂ O・Al ₂ O ₃・8SiO ₂・144H ₂ O・1.34Na ₂ SO ₄ mol A second aqueous mixture of the composition was prepared. Next, this second aqueous mixture was stirred and aged at room temperature for 16 hours, and then 850 g of each was mixed with 150 g of the above-mentioned first aqueous mixtures D, E, and F, and each mixture was subjected to the conditions shown in Table 5. A heat treatment was performed to form crystals. Thereafter, each product was filtered and washed and subjected to analysis. The results are shown in Table 5. Incidentally, all the products were faujasite type zeolites.

[Table] Comparative example 464g of sodium aluminate solution (Al ₂ O ₃ 22%, Na ₂ O 17.4%) prepared in advance and 1199g of 47% caustic soda solution were mixed, and this was further mixed with sodium silicate solution (SiO _{2 29%, Na 2} O 17.4%). 2483 g of Na ₂ O (9.14%) were rapidly mixed with stirring. This mixture solidified into a rigid gel, so it was transferred to a kneader, and 2173 ml of water was added while stirring vigorously to form a slurry.
The molar composition of this slurry is 12Na ₂ O・Al ₂ O ₃・
It was 12SiO ₂ .264H ₂ O. To 150 g of this slurry, 428 g of sodium silicate solution (SiO ₂ 29%, Na ₂ O 9.14%), 171 g of sodium aluminate solution (Al ₂ O ₃ 22%, Na ₂ O 17.4%) and 216 ml of water were added sequentially while stirring. plus 98 at the end
% concentrated sulfuric acid and 2Na ₂ O・Al ₂ O ₃・
A reaction mixture with a molar composition of 6SiO ₂ .100H ₂ O.1.13Na ₂ SO ₄ was obtained. The reaction mixture was then stirred at a temperature of 100° C. for 9 hours to form crystals, and the product was filtered and washed for analysis. This product has a SiO ₂ /Al ₂ O ₃ molar ratio =
4.6, Zeolite content = 92%, Crystallite diameter = 1000
It was a phosiasite type zeolite of Å.

Claims (1)

[Claims] 1 (a) Using silica sol, sodium aluminate and sodium hydroxide as raw materials, 2 to
A first aqueous mixture represented by the molar composition formula 3.4Na ₂ O・Al ₂ O ₃・6~9SiO ₂・90~120H ₂ O is prepared, and this mixture is aged under conditions that do not cause crystallization. b) Using sodium silicate, sodium aluminate and mineral acids as raw materials, 2-4Na ₂ O・Al ₂ O ₃・6
~ _9SiO2・90~ _150H2O・0.5~ _2.5Na2X (However,
(c) preparing a second aqueous mixture represented by the molar composition formula (X is an acid group of a mineral acid represented by a divalent value);
The aqueous mixture was prepared at a weight ratio of 3:97 to the latter.
The molar ratio of SiO ₂ /Al ₂ O ₃ is 4 or more, and the mixture is heated at a temperature where crystallization occurs for a time sufficient for crystallization. A method for producing faujasite-type zeolite having a particle diameter of 1400 Å or more. 2. The method according to claim 1, wherein in step (a), the first aqueous mixture is aged at a temperature of 80° C. or lower for 10 hours or more. 3 In step (a), the first aqueous mixture is heated to 80 to 110°C.
Claim 1, which is aged for 1 to 10 hours at a temperature of
The method described in section. 4. The method according to claim 1, wherein in step (a), the first aqueous mixture is aged at a temperature of 80°C or lower for 10 hours or more, and further aged at a temperature of 80 to 110°C for 1 to 10 hours. . 5. The method according to claim 1, wherein in step (b), No. 3 silica is used as the sodium silicate and sulfuric acid is used as the mineral acid. 6 In step (c), the weight ratio of the first aqueous mixture to the second aqueous mixture is 5:95 to 25:75, and the heating temperature and heating time are 90 to 100°C and 16 to 48 hours, respectively. A method according to claim 5.