JPS58213627A - Preparation of a-type zeolite - Google Patents

Abstract

PURPOSE:To prepare A-type zeolite consisting of uniform crystal particles having highly round edges, in high efficiency, by reacting an aqueous solution of sodium silicate with an aqueous solution of sodium aluminate under specific reaction condition. CONSTITUTION:A-type zeolite is prepared by the reaction of an aqueous solution of sodium silicate with an aqueous solution of sodium aluminate. The aqueous solution of sodium silicate is made to react continuously and instantaneously with the aqueous solution of sodium aluminate in a tubular reactor under the mixing flow of the flow rate of >=2m/sec, and the resultant gel is aged and crystallized by one or more procedures to give forced diffusion state and selected from high-speed agitation, ultrasonic vibration, shearing force and wet pulverization. A-type zeolite consisting of uniform crystal particles having highly round edges can be prepared in high efficiency by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing Am zeolite consisting of crystal grains with uniformity and rounded particle surfaces.

It has been known for a long time that zeolite (crystalline sodium aluminosilicate) has ion exchange ability, and recently progress has been made in the development of applications utilizing this as detergent builders. General formula [(1, θ±O, K) Na2
．． Oe AJ, OB ・(2,o±04)S10゜・
A-type zeolite represented by (0~t)H,o) is also a type of zeolite, but its production is generally done by mixing solutions of each component to form an amorphous aluminosilicate gel ( The method is based on a method in which a gel (hereinafter simply referred to as "gel") is precipitated and then crystallized.

The production of zeolite depends on the raw material liquid concentration, molar ratio (810x
/AJt OB ), gel formation method, aging temperature, aging time, etc., and many manufacturing methods have been proposed in which various combinations of these factors are used depending on the application.

Type A zeolite is a crystal that originally belongs to the equiaxed crystal system, so its particle shape tends to be a typical cube, and those produced by conventional methods are mostly composed of angular, dice-shaped crystal particles. There is.

However, Am zeolite, which generally consists of angular crystal particles, is different from Al zeolite, which consists of spherical or rounded crystal particles.
l Because it is inferior in purity and various performances compared to zeolite,
It is desired to establish a method for producing Am zeolite, which consists of rounded crystal particles as close to spherical as possible. In particular, when used as a detergent builder, Am zeolite, which has angular crystalline particles, has the drawback of easily forming aggregate particles due to primary aggregation, which causes significant deposits on clothing during washing, and fundamental improvements are needed. is desired.

Further, uniform primary particles are desired in various fields of use as desirable particle properties.

The present inventors conducted various experiments on a method of producing Afil zeolite by reacting an aqueous solution of Zyda silicate and an aqueous solution of sodium aluminate to produce an aluminosilicate gel, and then aging and crystallizing the skeleton gel. As a result of repeated research, it was discovered that by reacting an aqueous solution of sodium silicate and an aqueous sodium aluminate solution under specific conditions, AM and zeolite consisting of significantly rounded and uniform crystal particles could be efficiently obtained. The present invention has been completed.

That is, in the present invention, an aluminosilicate gel is produced by reacting a sodium silicate aqueous solution and a sodium aluminate aqueous solution, and then the gel is aged and crystallized to produce Am.
In the method for producing zeolite, the average flow velocity of a sodium silicate aqueous solution and a sodium aluminate aqueous solution is adjusted in a transportation pipe. ! very continuous under a mixed flow with a flow rate of 1/s or more;
This is a method for producing Am zeolite, which is characterized by instantaneous reaction and crystallization of the resulting gel. The present inventors previously proposed a method for producing A-type zeolite by continuously mixing a sodium silicate aqueous solution and a sodium aluminate aqueous solution without back-mixing to obtain a gel (Japanese Patent Application Laid-Open No. -1941). It was also disclosed that a tubular static mixing device such as a static mixer, a centrifugal pump, etc. can be used as a mixing device for carrying out the mixing reaction. However, as a result of subsequent studies, the inventors found that
Even without using a special mixing device as mentioned above, a sodium silicate aqueous solution and a sodium aluminate aqueous solution can be mixed continuously and instantaneously in an ordinary pipe for transporting liquid or gas without any mixing device. to produce a gel by
It has been found that by successive crystallization of the gel, a large zeolite consisting of crystal grains with uniformity and rounded particle surfaces can be obtained. That is, the present invention addresses the manufacturing method of Am zeolite, which consists of crystal grains with uniformity and rounded particle surfaces, by combining a sodium silicate aqueous solution and a sodium aluminate aqueous solution in a pipe that is not equipped with a mixing device. The average flow velocity of the mixture in the latter pipe (hereinafter referred to as "mixing zone") is Jm
This is a method for producing All zeolite in which the q# characteristic is to simultaneously and continuously inject the zeolite at the same time so as to instantaneously generate a gel, and then crystallize the gel. Under the conditions for producing the gel according to the present invention, the sodium silicate aqueous solution and the sodium aluminate aqueous solution are mixed continuously, instantaneously, and in one complete manner. Under such conditions, a good mixing state is obtained and a homogeneous gel is produced, and the A-type zeolite particles obtained through continued crystallization become crystal particles with uniformity and rounded particle surfaces.

One of the important requirements in the production method of the present invention is a gel preparation method in the reaction of mixing a sodium silicate aqueous solution and a sodium aluminate aqueous solution to obtain an amorphous aluminosilicate gel. The raw materials used in the manufacturing method of the present invention are a sodium silicate aqueous solution and a sodium aluminate aqueous solution, and their concentrations are:
The following ranges are suitable.

Sodium silicate aqueous solution: Nano s-20% 810
, ! -20 Sodium thialuminate aqueous solution: Na, O, j ~ 0% A
j, Ojl ~20% Sodium silicate aqueous solution and sodium aluminate aqueous solution are simultaneously and continuously injected into the mixing zone, but at this time, the average flow rate in the mixing zone is kept at a state of -m/* or higher to form a homogeneous gel. The first feature of the method of the present invention is the preparation. The temperature of the raw material sodium silicate aqueous solution and sodium aluminate aqueous solution used for this gel preparation does not need to be particularly limited, but if the temperature of the mixing zone is relatively low, the viscosity of the gel produced will be high and a good mixing state will be obtained. In addition, when the temperature is relatively high, the gel formation rate increases, and a heterogeneous gel is likely to be obtained. Therefore, the reaction temperature in the mixing zone is! θ
It is desirable to adjust the temperature of the raw material aqueous solution so that it is from 100°C to 100°C, preferably from &j'C to 0°C. Also,
The molar ratio of the gel composition that can be applied to the mixing zone (810,/Aut
It is important to adjust the amount of the raw material aqueous solution poured so that os) becomes o, s-1,j, preferably t, o-1,0. If the molar ratio of the kernels is outside the above range, the resulting gel will be heterogeneous, and it will be difficult to crystallize it and efficiently produce All-I zeolite particles with uniformity and rounded particle surfaces. Furthermore, in order to obtain a good mixing state in the mixing zone, it is important to suitably adjust the quantitative balance of the raw material aqueous solution. For example, when the concentrations of the raw material aqueous solutions are relatively high on one side and relatively low on the other, in order to maintain the molar ratio (810, /A and Os) in the mixing zone within the above-mentioned preferred range, it is necessary to adjust the injection flow rates of both solutions. A large difference occurs, making it more difficult to obtain good mixing in the mixing zone. According to the experimental results, the flow rate ratio (volume ratio) of the sodium silicate aqueous solution and the sodium aluminate aqueous solution is 0.2.
A range of ~/, j is preferred, and it is desirable to adjust the concentration of each aqueous solution to fall within this range.

In the gel preparation method according to the present invention, in which an aqueous sodium silicate solution and an aqueous sodium aluminate solution are simultaneously and continuously injected into a mixing zone to produce a homogeneous gel, dynamic and static mixing means are used as a mixing device. There is no need for equipment equipped with this, and by simply adjusting the injection rate of the raw material solution, the sodium silicate aqueous solution and the sodium aluminate aqueous solution can be continuously mixed.
Instant and complete mixing can be achieved,
It is possible to obtain homogeneous gels. As the mixing zone device in the method of the present invention, commercially available pipes for transporting liquid or gas can be used. The aqueous sodium silicate solution and the aqueous sodium aluminate solution are sequentially combined in piping using a Y-shaped tube, a T-shaped joint, etc., pass through a mixing zone, form a gel, and are charged into an apparatus for crystallization. In the gel preparation method according to the present invention, it is essential to maintain the average flow rate of the gel composition in the mixing zone at fn/sec. If the average flow rate is less than -m/sec, the mixing effect in the mixing zone will be insufficient and the resulting gel will be non-uniform. The greater the average flow velocity is JWL/sec or higher, the better the mixing effect will be.
Since special equipment is required for the raw material supply pump and piping materials, it may be selected appropriately. Further, although the time for passing through the mixing zone is not particularly limited, experimental results have shown that a good mixing state can be obtained in a very short time of several seconds. Even if the passing time was increased to 10 seconds or more, no commensurate improvement in the mixing effect was observed.

Furthermore, even if the passage time is relatively long, the average flow velocity is J m
If the time is 7 seconds or less, a homogeneous gel cannot be obtained. As the piping material used for mixing, general commercially available power distribution materials can be used. However, the gel produced in the mixing zone is very viscous and tends to adhere to the inside of the mixing zone tube and cause blockage. It was found that the adhesion of this gel differed slightly depending on the piping material. It was found that steel pipes and stainless steel pipes are relatively prone to adhesion, while polyvinyl chloride pipes, polypropylene pipes, chloroprene rubber-lined pipes, etc. are less likely to adhere.

In the production of A-type zeolite, the gel preparation method by mixing the raw material solutions of sodium silicate aqueous solution and sodium aluminate aqueous solution greatly affects the quality of A-type zeolite. has been done. However, most of them apply strong stirring force, shearing force, etc. from the outside during mixing.7. Also the contents.

It is. The method of the present invention does not require such an external mixing operation or a static device that promotes mixing, and achieves a mixing effect that yields a homogeneous gel by the mixing action generated by the flow characteristics of the fluid itself. be done.

The gel thus obtained is subjected to aging in order to immediately crystallize it. This ripening for crystallization is carried out by stirring the gel or other suitable diffusion means. Furthermore, it is often preferable to force the diffusion state if necessary.

Note that the forced diffusion state here refers to violently or forcibly dispersing particles by a method other than normal stirring and mixing, such as high-speed stirring at a rotation speed of 11,000 rpm or more, ultrasonic vibration, shearing force, or Examples include operations such as wet grinding.

Of course, such a forced diffusion state may be maintained throughout the entire time required for crystallization due to aging of the gel;
The state may be maintained for a certain period of time. Further, the operation for providing this forced diffusion may be incorporated into normal stirring and mixing. The ripening conditions during this period vary depending on the operating instructions and reaction conditions to be adopted, but generally 3.
A range of 1 hour to io hours at 0°C to tSO°C is suitable. In this case, when the temperature is low, the crystallization time becomes longer and the particles tend to become smaller. After crystallization, the zeolite slurry is passed through to separate and remove the mother liquor, washed by a conventional method, and then, if necessary, dried and pulverized to produce a product. On the other hand, the mother liquor separated in this step is an aqueous solution containing caustic soda as a main component, and in the present invention, this mother liquor can be reused cyclically in the raw material system, if necessary by concentrating it. That is, it can be used as a liquid for preparing a sodium aluminate aqueous solution and/or a sodium silicate aqueous solution.

AM zeolite produced by the method according to the present invention has crystal grains with rounded and smooth surfaces, and the average particle size is O,
S to jμ, and the particle size distribution is narrow and substantially uniform.

Furthermore, when individual crystal particles are observed using electron micrographs, it is observed that they are all spherical or extremely rounded particles without sharp apexes or ridge lines, and at the same time, the particle size distribution is extremely uniform.

The All-Al zeolite made of rounded crystal particles according to the present invention generally has high purity and is excellent in ion exchange ability, and has excellent dispersibility and suspension stability in aqueous solutions such as seri, sodium silicate, and surfactants. Because of its excellent properties, it is most suitable as a builder for detergents, and can be particularly effectively used as A-heavy zeolite for the preparation of "zeolite slurry for detergents" (% Kaisho J Gu 6S04L, etc.).

As described above, the type A zeolite according to the present invention is composed of crystal grains with remarkable roundness, has a uniform particle size distribution, and has various excellent properties.

In addition, the manufacturing process is based on a continuous reaction system, and the hot mother liquor can be circulated and used.The equipment is compact and consumes little energy, and products of constant quality can be efficiently obtained with short reaction and aging times. It is of high industrial value.

Hereinafter, this will be explained in detail using examples.

Example 1 Commercially available sodium silicate solution was diluted with caseinida solution and N
An aqueous sodium silicate solution containing a, Of, cowt%, SiO, t, and double Jl was prepared. Commercially available aluminum hydroxide was dissolved in caustic soda solution, and Na, OJr, 9 parts, 1 part,
A sodium aluminate aqueous solution containing 5.7% by weight of Ai and O was prepared. Both liquids were heated to 7θ℃, and the molar ratio of the mixing zone (S10□/A'zOa) was adjusted simultaneously via a pump.
The mixture was poured into the mixing zone so that the ratio was 9/2 to obtain an aluminosilicate gel. At this time, the piping of the mixing zone is JISK-4?4!
The average flow velocity in the mixing zone is 7. ．． 7 m/s, the mixed zone passage time is approximately (il
, 7 seconds.

When the gel thus obtained is placed in a container equipped with a stirrer and heated at 0°C for an hour with moderate stirring, a highly fluid slurry consisting of crystallized zeolite fine particles and an alkaline solution is obtained. Ta. The zeolite in this slurry is separated from the mother liquor by filtration and washing, then dried and ground, and subjected to Xa diffraction, electron microscopy, Coulter Counter method particle size distribution measurement, etc. to determine the substance content, particle shape, particle size distribution, etc. The results shown in Table 1 were obtained by measuring the Ca ion exchange capacity and the like.

An electron micrograph (magnification: 500x) of the obtained zeolite is shown in Figure 1. The zeolite is a cubic crystal with a particle size of 1 to 3 μm, rounded corners, and uniform particles with an extremely sharp particle size distribution. It consists of Furthermore, each particle existed separately from other particles, and no secondary aggregation was observed, indicating good dispersibility.

Example Using the same raw materials as in Example 1, a gel was produced by the same operations. The gel is placed in a container equipped with an ultrasonic oscillator,
Heating at 80°C for 2 hours under ultrasonic vibration (JjKI(I)) produced a highly fluid slurry consisting of crystallized zeolite fine particles and an alkaline solution.The subsequent operations were as described in Example 1. The results of one analysis are shown in Table 1.
All-Al zeolite having properties and performance almost equivalent to those of Example 1 was obtained.

Example 3 Using the same raw materials as in Example I, zeolite crystal particles were obtained by the same operation, except that the piping for the mixing zone was a hard vinyl chloride pipe with a nominal diameter #0 according to JI8-1694I/. Table 1 shows the analysis results of the six zeolites obtained. A zeolite having the following properties was obtained.

Comparative Example Zeolite crystal particles were obtained using the same raw materials and the same operations as in Example 1. However, the average flow velocity in the mixing zone is i, am
7 seconds, and the soaking time of the mixed zone was about 10 seconds. The analysis results of the 1% zeolaite are shown in Table 1, and the electron micrograph is shown in Figure 1.

The obtained zeolite has a broad particle size distribution and is inferior to the zeolite obtained in Example 1 in terms of Ca ion exchange ability. Electron microscopy (1000x magnification) reveals that the particles are non-uniform and are secondary agglomerated.

Table l *Calcium chloride aqueous solution at S℃ (concentration 3001
90 aO/J) with zeolite [Nano @Aj
2o, -5io,] to a concentration of /f/JL, stirred for is minutes, and measured the calcium concentration in the liquid.

[Brief explanation of the drawing]

FIG. 1 is an electron micrograph of a zeolite obtained according to the present invention, and FIG. 1 is a ring micrograph of a zeolite obtained in a comparative example. Patent applicant Nihon Kagaku Kogyo Co., Ltd. +-, -'4-. il

Claims (1)

[Claims] In the method, an aluminosilicate gel is produced by continuously reacting a sodium silicate aqueous solution and a sodium aluminate aqueous solution using a tubular reactor under a mixed flow having a flow rate of com/sec or more. A method for producing Afi zeolite, which is characterized by aging and crystallizing the gel obtained. The molar ratio (Sin, /AJ, 0.) of the sodium silicate aqueous solution and the sodium aluminate aqueous solution is o, s or co,
5. The method for producing A-type zeolite according to claim 1, wherein the reaction is carried out in a range of 5. 3. A according to claim 7 or 1, wherein the tubular reactor for reacting the sodium silicate aqueous solution and the sodium aluminate aqueous solution is made of polyvinyl chloride.
Manufacturing method of m-zeolite. Group A according to claim 1, wherein the gel is matured by an operation that provides a forced diffusion state of at least one of high-speed stirring, ultrasonic vibration, shearing force, and wet grinding. Zeolite manufacturing method. The method for producing type A zeolite according to claim 1 or 5, wherein the forced diffusion state is the entire period during which the gel matures and crystallizes. (v) Claim 1 or S characterized in that the forced diffusion state occurs during a part of the period during which the gel matures and crystallizes.
The method for producing Am zeolite described in Section 1. ! The method for producing Am zeolite according to claim 1, d, 5 or j1!61, characterized in that crystallization by aging of the gel is carried out by stirring and mixing and forced diffusion.