JPS61111912A - Production of crystalline aluminosilicate zeolite - Google Patents

Abstract

PURPOSE:To produce the titled zeolite having improved utility of a silica source and an alkali source, by selecting the composition of an aqueous reaction mixture to which the second alumina source is added, the timing of the addition, the kind of the second alumina source, and the amount of the source. CONSTITUTION:An aqueous reaction mixture having an oxide molar ratio of SiO2/Al2O3=3-20, M2O/Al2O3=2-6 (M is alkali metal) and H2O/Al2O3=50-300 is prepared, heated at >=50 deg.C, and added with the second alumina source to complete the crystallization of the crystalline aluminosilicate zeolite. The produced crystal is recovered to obtain the titled zeolite. The amount of the second alumina source added to the mixture is preferably <=100% of the alumina existing in the above aqueous reaction mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing crystalline aluminosilicate zeolite, and more specifically, the utilization rate of raw materials used in producing crystalline aluminosilicate zeolite can be improved, particularly by controlling the silica source and alkali source. The present invention relates to a method for producing crystalline aluminosilicate zeolite that improves the utilization rate of zeolite.

Crystalline aluminosilicate zeolite can be prepared by using appropriate silica source, alumina source, alkali source and water.
/person'Am''tQ/person1,0. (M represents an alkali metal) and each oxide molar ratio of H1O/A1tOs is,
The process is carried out by preparing an aqueous reaction mixture within a specified range and subjecting the mixture to a reaction field for a sufficient period of time at a temperature sufficient to cause the zeolite to crystallize. The silicon ratio (means the molar ratio of SiO, /Al, O8; the same applies hereinafter) of the crystalline aluminosilicate zeolite produced from the aqueous reaction mixture is generally determined by the silica source, alumina, It is influenced by the type of source and alkali source, the oxide molar ratio in the aqueous reaction mixture, and the crystallization conditions.

By the way, the Capan ratio of faujasite-type zeolite is usually in the range of 2 to 6, and in order to produce such zeolite, an aqueous zeolite having a Capan ratio that is much higher than the Capan ratio of Faujasite-type zeolite is required. A reaction mixture must be prepared. However, when the phosphor ratio of the aqueous reaction mixture is increased, a long time is required for crystallization, and there is a disadvantage that the yield of zeolite decreases when a reasonable reaction time is used.

This means that the utilization rate of the silica source and the alkali source contained in the reaction mixture is low.

The utilization rate of the silica source (or alkali source) is expressed as follows.

In order to avoid economic losses caused by insufficient utilization of the silica source and alkali source contained in the reaction mixture, conventional methods have been adopted to recover and reuse the unused silica source and alkali source. . For example, US Patent No. 41645
No. 51, the crystalline aluminosilicate zeolite formed in the aqueous reaction mixture is separated by filtration, an aluminum sulfate solution is added to the resulting mother liquor to form a silica-alumina hydrogel, and this gel is filtered and washed. Methods are taught for reuse as feedstock for aqueous reaction mixtures. However, recovering unused silica and alkali sources and reusing them is not necessarily practical due to the high cost of recovery.

The present invention is a process for producing a crystalline aluminosilicate zeolite in an aqueous reaction mixture, more specifically, by adding a second source of alumina to the reaction mixture before the crystallization of the zeolite is completed. While increasing the utilization of the 7-liquid and alkali sources in the aqueous reaction mixture without reducing the crystallinity of the produced zeolite, the high Ca d crystalline aluminosilicate zeolite) t-
Provided is a method for manufacturing with high yield.

That is, in the method of the present invention, the molar ratio of oxides is 8 io,
/ Al! 0. ±3~20M, O/At, Ol
w 2-6 (here M indicates an alkali metal) H, 07 people 1. Prepare an aqueous reaction mixture in the range Q, = 5Q to 30G, and add this mixture to at least 50
In the process of crystallizing the aluminosilicate zeolite by heating at a temperature of 100°C, $2 of alumina source is added to the mixture to complete the crystallization reaction, and then the resulting crystalline aluminosilicate is removed from the reaction mixture. It consists of collecting.

Roughly speaking, when producing crystalline aluminosilicate zeolite from an aqueous reaction mixture with the following composition, if an alumina source is added to the reaction mixture, the utilization rate of the silica source and alkali source contained in the reaction mixture can be fully utilized. can be improved. However, in that case, the phosphor ratio of the crystalline aluminosilicate zeolite produced decreases. However, according to the method of the present invention, by appropriately selecting the composition of the aqueous reaction mixture to which the second alumina source is added, the timing of its addition, and the type and amount of the second alumina source, the production of zeolite can be controlled. It is possible to increase the silica-9 ratio rather than decrease it, and therefore, it is possible to improve the utilization rate of the silica source and the alkali source.

In the method of the present invention, an aqueous reaction mixture having an oxide molar ratio in the range shown below is first prepared.

(A) Sid, /At, 03 w 3-20M, O
/At, O1 = 2 to 6 H,0/Al, O, = 50 to 300 For the preparation of this aqueous reaction mixture, conventionally known silica sources, alumina sources, and alkali sources can be used. For example, in the production of faujasite-type zeolite, silica sol, sodium silicate, white casene, etc. have been used as silica sources, sodium aluminate, aluminum sulfate, etc. have been used as alumina sources, and caustic soda has been used as alkaline sources. However, in the present invention, these raw materials can also be used to prepare the above-mentioned aqueous reaction mixture.

An aqueous reaction mixture with an oxide molar ratio in the range of
After aging at room temperature if necessary, at least 50
''C, preferably at a temperature of 80-150°C. During the aging stage at room temperature, a crystal precursor of crystalline aluminosilicate zeolite is formed, and during the heating stage, the crystallization (crystal growth) of the zeolite is also induced. ) is considered to occur.

According to the method of the invention, a second alumina source is added to the aqueous reaction mixture in which zeolite crystallization is proceeding. This second alumina source includes aluminum hydroxide,
It is preferable to use one or more types of χ-alumina and ρ-alumina, and the aluminum hydroxide mentioned here includes crystalline aluminum hydroxide such as jibside, k-mite, nonoiarite, alumina hydrogel, Included are amorphous aluminum hydroxides such as alumina hydrosil. The second alumina source of the present invention needs to be relatively unreactive. By the way, if this alumina source is a highly reactive alumina source such as sodium aluminate or aluminum sulfate, in other words, it is a highly water-soluble alumina source, the utilization rate of the silica source and alkali source can be improved to a certain extent. .

However, the zeolite ratio of the produced zeolite is significantly lowered, and sometimes zeolite crystals may not even be produced. Further, when the second alumina source is α-alumina, r-alumina, η-alumina, etc., which have very low reactivity, it is not possible to improve the utilization rate of the silica source and the alkali source as in the present invention. .

The amount of the second alumina source added is such that the oxide molar ratio is (
A) The amount of alumina in the aqueous reaction mixture ranges from 10 to 10.
0% or less. Addition of more than this is not preferable because the silicon/carbon ratio of the produced zeolite will drop significantly. As mentioned above, the second alumina source can be added once or in multiple portions at any time during the process of crystallization of zeolite in the aqueous reaction mixture. In general, zeolites with higher capane ratios can be produced.

However, it is necessary to add the second alumina source before the crystallization of the zeolite is completed, and addition after the crystallization is completed may improve the utilization rate of the silica source and the alkali source. Can not. The effective timing for adding the second alumina source is preferably in the first half of the heat aging stage.

The aqueous reaction mixture is maintained at a temperature of at least 50° C. during and after the addition of the second alumina source, preferably between 50° C. and 150° C., which temperature is sufficient to induce crystallization of the zeolite. will be maintained until completion. After the crystallization is completed, the desired crystalline aluminosilicate zeolite can be obtained by recovering the crystals from the aqueous reaction mixture according to a conventional method.

As described above, according to the method of the present invention, in contrast to the conventional practice, crystalline aluminosilicate zeolite with a high capane ratio is produced by improving the utilization rate of the silica source and the alkali source contained in the aqueous reaction mixture. The reason for this can be explained as follows.

That is, in the method of the present invention, the aqueous reaction mixture before adding the second alumina source has the oxide molar ratio shown in (A) above. Adding a second alumina source to this aqueous reaction mixture will naturally reduce the capane ratio of the aqueous reaction mixture, so typically
The zeolite obtained from this aqueous reaction mixture has a reduced Capan ratio compared to the zeolite obtained from the aqueous reaction mixture before addition of the second alumina source. However, in the method of the present invention, crystallization of zeolite is first started in an aqueous reaction mixture having the oxide molar ratio shown in (A) above, and a second alumina source is added while the crystallization is progressing. and because the alumina source is relatively unreactive, the molar ratio of dissolved silica to dissolved alumina in the aqueous reaction mixture in which zeolite crystallization is proceeding is reduced by the addition of a second alumina source. It is assumed that the method of the present invention can improve the utilization of silica and alkali sources without reducing the Si/Man ratio of the zeolite. .

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Sodium aluminate solution (AI, 0.22%) 2086
g was weighed and mixed with 958 g of 48% caustic soda bath solution. Add 1548cc of water to this, and add 7176g of silica sol (810t 30%) to 60ml while stirring rapidly.
The aqueous reaction mixture (with a ratio of 8.0
A silica-alumina hydrogel slurry) was prepared. Stirring was stopped and the mixture was left at room temperature for 16 hours. The reaction mixture is then heated to 95"C for 2 hours to crystallize, and then added with a second source of alumina in an amount sufficient to reduce the Si/Man ratio of the original aqueous reaction mixture to 1C6,0. was added and crystallization was further carried out for 46 hours. Gibbsite obtained by the Nononyer method was used as the second alumina source in the first experiment, and gibbsite was heated in a hot air stream at 600°C in the second experiment. χ-alumina obtained by firing in a vacuum chamber was used.

After completion of crystallization in each experiment, the mixture was cooled to 40'C, dehydrated and filtered, washed with sufficient water and dried to obtain zeolite. The yield, capane ratio, crystallinity, and utilization rate of silica source and alkali source were measured for this zeolite. In addition, the crystallinity is determined by X-ray analysis as 20=2 on the chart.
3.6 and 26.9 peak areas (commercially available zeolite)
(-40 to 8), and the utilization rates of silica source and alkali source were determined by chemical analysis. The results are shown in Table-1.

In addition, for comparison, a sodium aluminate solution (λ1, 0.2
2%) 2086g and 48% caustic soda solution c + 58gt
- Mix silica sol (Si) with rapid stirring.
An aqueous reaction mixture (silica-alumina hydrogel slurry) with a Ca-Man ratio of 6.0 was prepared by adding 5399 g of C.n., 30 g over 60 minutes.

After stirring was stopped and the mixture was left at room temperature for 16 hours, 95
Crystallization was carried out for 48 hours by heating to °C.

After crystallization, the mixture was cooled to 40°C and filtered with water.
Then, it was washed with sufficient water and dried to obtain a comparative zeolite (C)'e. This zeolite (C) was also subjected to the same measurements as the previous zeolite. The results are shown in Table-1.

Table-1 Starting mixture composition S amount 0. /At, 0. 8.0 g
, 0 6. ONa, O/At, 0. 2
．． 60 2.60 2.60H,0/At
,0. 106 106 106 Added alumina source Gibbsite χ-alumina
- Mixture composition after addition 3 i 02/Al t Os 6.0
6.0 6.0Na20/person 1,0,1
．． 95 1.95 2.60H,
O/Al, 0. 79 78 10
6 Zeolite yield (g) 2651 2643
18088 i 0t/Al, 0. 4.
8 4.8 4.1 Crystallinity 1
16 115 112 Silica utilization rate (%)
77.0 76.8 67.0 Alkali utilization rate (%) 49.3 49.2
37.7 As is clear from Table 1, zeolite with a Keipan ratio of 4.1 can only be obtained from a reaction mixture whose Keipan ratio is 6.0 from the beginning, but as in the method of the present invention, If a second alumina source is added during crystallization, the amount added will increase the capane ratio i of the starting reaction mixture.
Even if the amount is 6.0, it is possible to produce zeolite with a weight ratio of 4.8.

Example 2 An aqueous reaction mixture with a capane ratio of 8.0 was prepared in exactly the same manner as in Example 1, and after stopping stirring, it was left at room temperature for 16 hours to obtain a slurry (X)t-. This slurry (X)t-ss
After allowing crystallization to proceed for 12 hours by heating to 100 °C, enough Bayer Gibbsite to reduce the original aqueous reaction mixture to a t-7.0 concentration was added to the slurry for an additional 46 hours. Crystallization was performed. After the crystallization was completed, the product was treated in the same manner as in Example 1 to obtain zeolite (e).

In addition, zeolite was prepared in exactly the same manner as above except that the amount of the initial aqueous reaction mixture of the gibbsite mother metal added to the slurry (X) was adjusted to reduce the K-N ratio to 5.0 and 4.0.
(f) and (g) were obtained. Furthermore, for comparison, the slurry (X) without addition of 1-95"C
and crystallize for 48 hours to obtain zeolite) (d)
'? Obtained.

The zeolites (d) to (g) thus obtained were subjected to the same measurements as in Example 1, and the results shown in Table 2 were obtained.

(Left space below) From the comparison between (d) and (e) of Zeolite in the above table, it can be seen that according to the present invention, by adding the second alumina source, the silica source, Yield of zeolite by improving utilization rate of alkali source
- Can be increased.

Example 3 96 cc of water and water glass (8i0.24%, Na20/
S + 01 = 3.3) 405g and 48g caustic soda 1
87 g were mixed. Add this to sodium aluminate solution (A
110,322%) stg and 138 cct of water were added with stirring to prepare a silica-alumina hydrogel slurry, which was left at -30''C for 20 hours to seed (5e
ed) It was made into a slurry.

Next, Metakaori/(person 1) was pre-baked at 600℃ for 2 hours.
,0.・2SiO,)1323.4gk water 600/c
C, and while stirring, add the water glass 860
Add 7.5 g and add 48% caustic soda 668.8 g.
ft-added. After that, 876.6g of the seed slurry prepared earlier was mixed and stirred for 3 hours until the Capan ratio was 8.
0 slurry (Y) was obtained.

After heating the slurry (Y) to 95°C, Noyer method gibbsite is added to the slurry (Y) in an amount that reduces the Keinotan ratio of the slurry (Y) to 6.0,
Heating was continued for 48 hours to complete crystallization of the zeolite. Thereafter, the produced zeolite was treated in the same manner as in Example 1 to obtain zeolite (h)'f:.

In addition, the timing of adding gibbsite to the slurry (Y) was shifted to 2 hours, 4 hours, 6 hours, 8 hours, and 10 hours after the slurry (Y) reached 95"C, and gibbsite was added. The subsequent crystallization time is 46, respectively.
Zeolite (i) ~
(m)e got it. Furthermore, for comparison, the Keino 9 ratio is 8.0 without adding Gibbsight. Slurry of O (Y)t-95
The zeolite (
n) was obtained. In addition, after 6 hours had elapsed after heating the slurry to IJ-(Y)'t95''C, sodium aluminate was added to the slurry in an amount that would reduce the Capan ratio 'i of the slurry to 6.0, and crystallization was carried out for 42 hours. However, in this case, it was not possible to obtain zeolite crystals.

The same measurements as in Example 1 were performed for each of the above zeolites) (h) to (n), and the results shown in Table 3 were obtained.

(Left below) As is clear from Table 3, when implementing the method of the present invention, as long as the second alumina source is added during the process of zeolite crystallization, the later the addition time, the higher the capacitance. The ratio of zeolite can be developed.

Claims (1)

[Claims] 1. Aqueous oxide having a molar ratio of SiO_2/Al_2O_3 = 3 to 20 M_2O/Al_2O_3 = 2 to 6 (here M represents an alkali metal) H_2O/Al_2O_3 = 50 to 300 preparing a reaction mixture and heating the mixture at a temperature of at least 50° C. to crystallize the crystalline aluminosilicate zeolite, adding a second alumina source to the mixture to complete said crystallization; 1. A method for producing crystalline aluminosilicate zeolite, which comprises recovering the crystals produced after that. 2. The method according to claim 1, wherein the amount of the second alumina source added is 100% or less of the amount of alumina contained in the aqueous reaction mixture. 3. The method according to claim 1, wherein the second alumina source is one or more of aluminum hydroxide, χ-alumina, and ρ-alumina. 4. The method according to claim 1, wherein the crystalline aluminosilicate zeolite is a faujasite type zeolite.