SK7542001A3 - A method for producing synthetic zeolites with enlarged grain size and zeolites with enlarged grain size produced by the said method - Google Patents

Abstract

A process for producing synthetic NaA, NaX, NaY zeolites or their mixtures comprising: a gel is prepared by means of mixing together intensively a mixture of sodium aluminate solution, water-glass solution and water (solution 'A'), a mixture of water-glass solution and water (solution 'B') and intensive stirring of synthesis nuclei solution formed by intensive mixing together of solutions 'A' and 'B', the formed gel is crystallized with a slow stirring up to the moment of the highest crystallization rate (tinfl), then a crystal size growing gel, free of synthesis nuclei and having mole ratio limits identical with initial gel is added in one or several portions and the crystallization proceeds with a slow stirring, and if required, the addition of the crystal size growing gel and the following crystallization are once or more times repeated, thereafter the obtained crystals are separated, washed and dried by a known method.

Description

Process for producing synthetic zeolites NaX, NaY and variants thereof

Technical field

The present invention relates to a process for the production of synthetic zeolites NaA, NaX, NaY or mixtures thereof, characterized by an increased grain size.

A further object of the invention are zeolites and mixtures thereof prepared as described above. The advantage of the increased grain size zeolites of the present invention is the improved surfactant retention capability and greater grain size distribution homogeneity.

BACKGROUND OF THE INVENTION

It is known that natural and artificial zeolites crystallize spontaneously. According to Breck's manual (E.D.W. Breck: Zeolite Molecular Sieves, J. Wiley, 1974), 17 types of zeolites can be formed in a quaternary system containing components S1O2, Al2O3, Na2O and H2O.

These zeolites do not crystallize in a well-defined composition, but crystallize in a more or less wide range of different compositions, which are usually illustrated by a ternary diagram (at constant temperature and H ₂ O content), see p. 270 of Breck's Manual).

In FIG. 1 is a crystallization field or range indicated by a dotted surface in which NaA is able to crystallize in a composition corresponding to a defined point of the ternary diagram, based on 1 mole of Al 2 O 3, at H 2 O = 94 mol and T = 88 ° C.

Methods for producing NaA zeolite are described in Hungarian patent no. 198,892 and U.S. Pat. 4,222,995, 4,230

627, 4 303 628, 4 305 916, further in German documents unloaded for public inspection (Auslegeschrift) 2 651 419, 2 651 420, 2 651 436, 2 651 437, 2 651 278.

In the above diagram, the formation of crystallization nuclei within area T is rapid, at point B it is much slower and more stable and at point C the spontaneous formation of crystallization nuclei is practically zero.

It is known that the tendency to form cores increases with increasing amounts of gel-facilitating ingredients (in fact Na2O) under otherwise unchanged other conditions.

The crystalline phase composition (zeolite), i. the most typical Si / Al ratio may vary to some extent, which is typical of a zeolite type structure (with identical radiographic lattice structure such as FAU = faujasite, MFI = ZSM-5, with the highest thermal stability), must reduce by the ratio of which concentration if the variant is produced

Si / Al (i.e., the highest defined (i.e., characterized by an alkaline step that ensures complete loss of crystallization) is also performed when the aluminum silicate is not due to the alkaline agent but to the formation, i.e., the fluoride ion.

This implies that nuclei formation and gel crystallization are separated in space and time during the synthesis of artificial zeolites.

reagent ability spontaneous

This dissolved complex,

This procedure is necessary in some cases and advantageous in others.

Without these conditions, the crystalline phase could not be produced primarily as structurally pure and if only with great difficulty or not at all.

The homogeneity of the zeolite phase should be ensured but in some cases may not be ensured.

For some specific purposes (e.g., water softening) in various industrial applications (such as detergent production), not one but two types of zeolites are used, and a process wherein not one but two phases simultaneously (NaA [ LTA] and NaX [FAU], as shown in the example).

It is well known from many patents to promote crystallization, which utilizes gel maturation, introduction of crystallization cores, as well as seeding with various crystallization cores.

To promote the crystallization of NaX and NaY, the cores are produced by the gel maturation method of Breck's original patent of 1964 (US Patent No. 3,130,007) and US Pat. No. 3,518,051 and 3,227,660. U.S. Pat. No. 4,264,562 relates to the formation of crystallization cores.

According to U.S. Pat. No. 4,264,562, activation of Nametasylikate is accomplished by the addition of Al2O3 to the metasilicate. The methods described in U.S. Pat. 3,071,434 and 3,322,272 use synthetically produced NaA, NaX and NaY as crystallization cores.

According to U.S. Pat. No. 4,404,823, NaX cores are used for the simultaneous production of NaA and NaX.

The crystallization of zeolite is according to U.S. Pat. No. 4,166,099 supported by cores with significantly larger surface area (~ 0.1 to 0.01 µm in size).

Crystallization cores are described in German documents unloaded for public inspection (Auslegeschrift) no. 2,447,206.

U.S. Pat. No. 4,178,352 and 4,340,573, a solid gel suspended in water is used as the core and, moreover, according to the latest patent, A1 cores are used to crystallize NaA.

Aging of gels and the addition of the silicate component to Al2O3 in an amount of 500-2000 ppm, as described in the aforementioned processes, it is difficult to reproduce in an industrial scale (as the commercially available water glass always contains a certain amount of A1 ₂ O ₃ as an impurity).

Solid gels dissolved in water have a non-reproducible structure, which can cause difficulties in large scale zeolite production. The same is true when zeolites with a non-homogeneous particle size distribution are used as cores. In this case, the heterodisperse nature of the particle size distribution will be inadvertently transferred to the product.

Separation carried out on a large scale by sedimentation or other methods entails considerable financial costs.

The use of crystallization cores should meet the following requirements:

(I) The first requirement is that the production of cores is reproducible both in the laboratory and in large-scale production, with a relative error of less than ± 20%. Since the cores embedded in the gel structure and the more or less crystalline reagents cannot be reproduced with such high precision, a core solution should be considered and preferred (this solution actually contains particles of colloidal size, less than 50 nm). (This knowledge has forced us to develop solutions of the present invention that contain N = 4.4 (± 0.9 ^ 10 ¹¹ crystallization cores per gram of liquid).

II) The amount of N cores should be sufficient to suppress, inhibit the possible formation of parasitic zeolite cores by eliminating the structure-forming components from the solution phase (usually aqueous).

III) The fulfillment of this condition depends on the structure of the crystallized zeolite:

NaA zeolite is undemanding in this respect. The amount of 0.1 * N (g ^-1 ) cores is certainly sufficient and 0.01 * N (g ^-1 ) is safely sufficient to control the actual crystallization of NaA in the slurry associated with the formation of NaA.

We have found that the same core solution is useful for crystallization of NaX and NaY. This means that the NaX and NaY cores are equal. Like NaX, zeolite cores crystallize in the rest of the silicate. As a result, no Al-core, as suggested in U.S. Pat. 4,340 573.

IV) The added cores must grow so that the zeolite has an optimum useful grain size Φ (μιη) and its homogeneous distribution in a batch of a defined quantity.

In addition to the conditions described in para. II there are certain independent conditions, the fulfillment of which is not automatically guaranteed.

There may be three cases:

The amount of nuclei N (g ^-1 ) contained in the weight unit of the core solution may vary to some extent, so that condition II is satisfied for a given bait. During this procedure, grains will form within a certain size range (<D _m i _n to Φ _ΜΧ ).

If the desired grain size Φ is within this range ( _{min min} to Φπιβχ), the grain size of the product may be increased by slightly reducing the amount of core solution added to the batch, or the grain size may be reduced by increasing the amount of solution, thereby meeting conditions II and III. .

If the desired grain size Φ is less than Φιηίη, then the amount of core solution added to the batch will increase.

In most cases the required grain size Φ is greater than 0 _max , so the number of cores N (g ^-1 ) should decrease in a certain batch. However, it cannot be reduced because condition II would not be fulfilled and in this case, a zeolite other than the desired one would crystallize due to the parasitic cores.

SUMMARY OF THE INVENTION

The present invention proposes a relatively simple process in which conditions II and III are simultaneously met and the requirement that allows the production of zeolite with any predetermined grain size Φ in the range of 1 to 20 µm, preferably in the practical range of 3 to 8 µm, is met.

On the basis of our research, the present invention relates to a deliberate, predefined grain size increase of synthetic zeolites which essentially consists in adding a gel without crystallization cores to the slurry to be crystallized, suitably at the time t _in fi »in the amount required. to achieve a predefined grain size Φ so that the maximum speed under the given conditions remains unchanged throughout the addition.

For this, it is necessary to adjust the composition of the added gel so as to avoid spontaneous formation of crystalline nuclei.

The slurry (i.e., gel + solution) meeting the above condition should be vaccinated to meet condition II, or the slurry must be prepared from a waterglass solution containing crystallization cores.

This waterglass solution is always doped with aluminum silicate (containing 8 moles of Al ₂ O ₃ to 15 moles of SiO ₂ ) and is very alkaline with a free NaOH content of 16 to 24% by weight.

Kernel formation is relatively fast under these conditions (only a few hours).

According to the invention, the addition of the grafted waterglass can be carried out in any sequence. However, it is preferable to add water glass to the finished gel.

Then, the slurry is heated to crystallization temperature and crystallization is started.

Zeolite with too small grain size should be taken without further intervention.

To avoid this, a slurry without crystallization cores is added to the crystallization vessel at a certain stage of crystallization, at a rate calculated according to the crystallized zeolite type and the desired grain size Φι. The crystallization is then continued at the maximum possible rate until the gel phase appears and a particle size of Φχ is reached.

It is important to define the gel addition time.

The crystallization rate is described by the differential relation.

(D where m / g / - is the weight of zeolite (grains or given number of grains) f (c) - is a function containing the concentration of aluminum silicate components (c) needed to build a crystal lattice

F / m ² / - is the surface area of the crystal (ον) exposed to the solution.

If the gel is present in an appropriate amount, i. f (c) = constant, this function can be replaced by the constant Ci.

Under these conditions, the differential relationship of the solution takes the form of a third-order polynomial time function for all crystalline forms:

m = Co + C _x t + C ₂ t ³ M + C ₃ t ³ M (2) which is an increasing convex function of time t.

With time, the gel is consumed and neither the condition f (c) = const, and consequently the relation 2, is fulfilled.

The convex nature of the function becomes concave at time t _inf i.

dm / dt decreases and points to zero, with increasing time the function m (t) reaches a constant cut-off value, as shown in FIG. Second

The core-free batch should preferably start at time tmfi and follow a certain time schedule until the optimum crystallization rate is reached.

It is preferred to add the gel continuously.

The rate of addition (g / s) should be appropriate so that the weight ratio of the zeolite-forming components corresponds to (dm / dt), i. zeolite crystallization rates.

It follows from formula (2) that dm / dt is a quadratic function of time, which means that, in order to ensure an optimal crystallization process, the filling should be carried out in a uniformly accelerated manner.

For this reason, it is advantageous to add the gel evenly with increasing speed. Although for technical reasons this condition cannot be met precisely, it may nevertheless approach this condition in various ways.

The total amount of gel subsequently added is determined from the desired grain size Φ (pm). It can be calculated, but is preferably determined experimentally to ensure reliable production.

These principles can be applied to different types of zeolites with appropriate treatment.

The product obtained by the process of the invention is considerably more homogeneous than using any other process where spontaneous core formation slows over time.

An unexpected result is that the crystallized zeolites exhibit longer sections of the periodic arrangement of their lattices than zeolites produced by another method, which usually manifest themselves in X-ray diffractograms of surprisingly intense reflexes at high 2 Θ angles.

We assume that transport processes occur more rapidly in a structure without sliding layers and other dislocations that can favorably affect adsorption as well as catalytic activity (for NaY zeolite).

The arrangement of the zeolite lattice makes it possible to increase the transport of ions in the aqueous environment and thus the rate of ion exchange. As a result, the wash water softens in a few minutes. For the process of the invention is characterized in that the slurry containing components of _SiO2, Al2O3, Na ₂ O and H ₂ 0, and crystallized crystallization nuclei in the course of time the _N fi, if the conditions of the highest crystallization rate. A new slurry containing the components SiO ₂ , Al ₂ O ₃ , Na ₂ O and H ₂ O without crystallization cores is then continuously fed into the mixture until the crystals have reached the desired grain size.

As mentioned above, the process of the invention is applicable to the production of a large number of different zeolites. Not only NaA and NaX type zeolites, but also NaY zeolites and mixtures thereof can be prepared by the above process.

The process has proven to be particularly advantageous for the production of Zeolite NaX or a mixture of NaX and NaA.

According to one variant of the invention, the NaX module zeolite m = 2.0 to 5.3 can be advantageously produced at pH =

13.2 by increasing the average grain size by several steps, using the production and addition of crystallization cores.

One important condition is that the pH of the slurry should not exceed 13.2 since spontaneous core formation begins at pH 13.3 to 13.4, and the addition of cores is then unnecessary.

The process for producing a zeolite with a grain size of Φ> 1 to 2 μιη consists of the following steps:

carrying out the first synthesis up to t _in fi results in the formation of a grain size product Φχ carrying out a second synthesis starting from time t _inf i which provides a grain size product Φ ₂ carrying out a third synthesis providing a grain size product Φ3 which can be vary between 3 and 10 μιη.

The question of whether crystallization cores should be added or not is addressed by the molar ratio of SiO ₂ , Al ₂ O ₃ and H ₂ O components in the slurry for the first synthesis.

To ensure that the pH of the first slurry never exceeds 13.2, it should be observed the following molar ratio: SiO ₂ / Al ₂ O 3 = 1.5 to 5.3 Na ₂ O / Al ₂ O ₃ = 1.5 to 2 5

H ₂ O / Al ₂ O ₃ = 88 to 260

To avoid spontaneous core formation, the slurries used for subsequent syntheses should have similar molar ratios.

During the following tests, we came to the conclusion that the stated goal can be easily achieved without producing and selling crystallization cores. As a result, the second variant, variant b of the process according to the invention, consists of producing zeolite NaX or a mixture of zeolites NaA and NaX, with a silicon to aluminum ratio of m = 2.5 to 5.3 and an average grain size Φ> 2 gm. NaY-type zeolite can also be produced in this way.

With increased alkali concentration, crystallization cores need not be produced and added.

The procedure consists of the following steps:

water glass, sodium aluminate, NaOH solution and distilled water are mixed to form solution A, i. a first synthesis slurry;

initiating a crystallization process;

water glass, sodium aluminate, NaOH solution and distilled water are mixed to produce solution C, i. a second synthesis slurry;

solution C is added to solution A, where crystallisation takes place;

completing the crystallization;

filtration, washing and drying the crystals.

It is essential to add solution C, which is prepared from the same components as solution A, at the appropriate time t _in fi after crystallization of solution A begins, as this ensures the form of NaX type zeolites of the correct grain size and avoids other undesirable zeolite types, e.g. . P zeolite (fillipsit), sodalite, etc. The molar ratios of the components in slurry A, based on 1 mole of Al ₂ O ₃ , are within the following ranges:

S1O2 / AI2O3 = 2 to 5.3 Na ₂ O / Al ₂ O ₃ = 2.5 to 7.5

H ₂ O / Al ₂ O ₃ = 88 to 260

The molar ratios of solution C have a much broader range, since spontaneous formation is guaranteed in its entirety.

The proportions of the components SiO ₂ , Al ₂ O ₃ , Na ₂ 0 and H ₂ 0 calculated per 1 mol of Al ₂ O ₃ are as follows:

SiO ₂ / Al ₂ O ₃ = 2 to 100 Na ₂ O / Al ₂ O ₃ = 2.5 to 100 H ₂ O / Al ₂ O ₃ = 88 to 5000

The size of the crystals formed can be very well controlled by selecting the correct moment of addition of solution C.

The appropriate moment, ie _n fi, is recommended to be determined in advance, experimentally.

If zeolite with an average grain size of 5 to 8 μιη is to be produced, solution C is added 1 to 2 hours after the start of crystallization of solution A.

If solution C is added to crystallization slurry A later, 3 to 24 hours after the start of crystallization, the zeolite crystals may grow to an average size of Φ = 15 to 30 μπι.

Accordingly, the present invention provides a process for producing synthetic zeolites of the NaA, NaX, NaY or mixtures thereof from sodium aluminate and water glass solutions.

From the above it can be stated that the characteristic features of the production method according to the invention are as follows:

Variant a)

A gel having the following composition is produced:

1.5 to 5.3 moles of SiO ₂ / l moles of Al ₂ O ₃

1.5 to 2.5 moles Na ₂ O / 1 mol Al ₂ O ₃ to 260 moles H ₂ O / 1 mol Ä1 ₂ O ₃ at the highest pH of about 13.2 by preparing a mixture of sodium aluminate solution, water glass solution and water (solution A) and a mixture of water glass and water solution (solution B). Solutions A and B are mixed by vigorous stirring to give a solution of synthetic cores. The above gel is seeded at the correct ratio of crystallized core solution with slow agitation until the highest crystallization rate (t _in fi) is reached, then a gel with the same molar ratio, without crystallization cores, is added to the primary gel in one or more portions, to increase the crystal size, and then crystallization is continued with slow agitation. The addition of the core-free gel can be repeated until the desired particle size is reached. The product is collected by filtration, washed and dried by known methods.

Variant b)

Mash A with a pH of at least 13.3, having the following composition:

2.0 until 5.3 M SiO ₂ / l M A1 ₂ O ₃ 2/5 until 7.5 M Na ₂ O / l M ai ₂ o ₃ 88 until 260 M H ₂ O / 1: M ai ₂ 0 ₃

is prepared by vigorously stirring the sodium aluminate solution, the water glass solution, and the resulting gel crystallizes at the right time, then solution C of the composition is added.

2.0 to 100 moles of SiO ₂ / l moles of Al ₂ O ₃

2.5 to 100 mole Na2O / Al2O3 mole to 5000 moles H ₂ O / 1 mol of Al2O3, obtained by homogeneously mixing a sodium aluminate solution, water glass solution and distilled water was added in one or more portions to the mixture, and crystallization is continued by one or more steps until the desired crystal size is achieved. Subsequently, the crystals produced are separated, washed and dried by known methods.

In addition, the present invention relates to NaA, NaX and NaY type zeolites or mixtures thereof produced by the above processes, characterized in that the average particle size is at least 1.0 μιη, preferably between 1.0 and 20.0 μπι.

The increased grain size zeolites of the present invention can be used in a wide range of applications.

The advantages of the zeolites produced according to the invention are as follows:

The most advantageous product can be used in a specific field of application due to the deliberate adjustment of the average grain size.

The grain size distribution and long portions of the periodic crystal lattice arrangement are more uniform than in the case of zeolites produced by traditional methods.

The production method and products of the invention are illustrated in the following examples.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

NaX-type zeolite is produced with a modulus of m = 2.6 (Si / Al = 1.3), at a pH of about 13.1, with an average grain size of about Φ = 3, in three steps:

Manufacture of synthetic cores

Two solutions labeled A and B are prepared as follows:

Preparation of solution

53.4 g of solid NaOH (containing 87% by weight of NaOH) are dissolved in 137.0 g of H ₂ O. This solution is added in 1: 1 weight portions to 14.1 g of alkali aluminate with a molar ratio of 1.58 Na ₂ % O / Al ₂ O ₃ and a NaOH concentration of 15.9 wt. and to 77.4 g of a waterglass solution with Na ₂ O concentrations of 8.6 wt. and SiO ₂ 28.0 wt.

The above-mentioned aluminate and waterglass solutions are heated to 60 ° C and mixed together with vigorous stirring, further stirred for 5 minutes and held at 60 ± 2 ° C for 70 minutes.

(A small amount of flocculent precipitate may form, which dissolves during heating.)

This homogeneous solution may be stored in the refrigerator for at least one week. To improve storage at room temperature, it can be mixed with waterglass B solution.

Preparation of solution

500 g of a waterglass solution with Na ₂ O concentrations of 8.6 wt. and SiO ₂ 28.0 wt. was diluted with 350 g H ₂ O.

To solution B, solution A is added with vigorous stirring. This mixture will hereinafter be referred to as cores. The mixture of these cores has the following composition: (96.6 SiO ₂ , 1.0 Al ₂ O ₃ , 49.8 Na ₂ O, 1858.0 H ₂ O) g of these cores contains 4.3 * 10 ¹¹ , with a relative deviation of ± 5%, cores of NaX and NaA type with grain size below 5 nm (undefined structure).

Performing the first synthesis

2000.0 g of H ₂ O and 432.2 g of cores was added to 1542.9 g water glass solution with a concentration of Na ₂ O 8.6% by weight. and SiO ₂ 28.0 wt. and the resulting solution is set aside.

3670.0 g of H ₂ O are added to 1362 g of sodium aluminate with a molar ratio of Na ₂ O / Al ₂ O _{3 of} 1.58 and a NaOH concentration of 15.9% by weight.

The two solutions are mixed with shear under intensive mixing. This procedure results in a gel. The gel is further stirred for 15 minutes. After stirring, the pH is 13.2.

This gel is allowed to crystallize by shear stirring slowly at 88 ± 2 ° C. Samples are taken at regular time intervals for X-ray diffraction analysis. The results of the measurements form a crystallization graph which is shown in FIG. Second

The molar ratios are as follows:

SiO ₂ A1 ₂ O ₃ Na ₂ O H ₂ O 2.99 1.0 2,489 165.27

The intensity of the corresponding maximum X-rays is proportional to the weight of the crystalline phase present in the volume of the sample.

The ordinates of FIG. 2 shows the summarized intensities of the most intense reflection, indexes [111], [220], [535], [642] / [646], [555], [157] / [751] samples taken at time intervals. A good result is also obtained when the measurement is performed only with reflection [555] / [157] / [751], which occur around a diffraction angle 2Θ = 30.9 ° (half the measured width * height).

From a graph constructed from the crystallization data of several batches, it can be seen that crystallization is complete after 5.5 to 6.0 hours (if only this single batch crystallized).

The time corresponding to the inflection point is: t _in fi = 3.2 hours

After six hours of crystallization, the product is filtered off, washed with hot distilled water to pH = 10.5, then dried with a stream of air at 100 ° C and finally stored over a saturated NH ₄ Cl solution.

The Si / Al ratio is defined using an atomic adsorption spectroscopy (AAS) system such as Si / Al = 1.36, modulus m = 2.72.

The composition of an elementary cell is:

Na8i [AlC> 2) 81 (SiO2) in] ~ 260 H2O which differs only by 5 to 6% from the typical NaX composition:

Na86 [A102) 86 (SiO2) 10O] - 264 H2O

The theoretical yield is determined on the assumption that the total amount of Al ₂ O ₃ is transferred to the product (with a high approximation).

The weight of the zeolite containing 1 mol Al ₂ O ₃ should be:

2.27 SiO ₂ 1.0 Al ₂ O ₃ 1.0 Na ₂ 0 6, 4 H ₂ O = 442.6 g The theoretical yield (the above batch) is therefore: 2.655 * 442.6 = 1175.1 g

Weight of crystallized slurry: 9056.0 g (also for the above batch)

As a result, Φ = 1175.1 / 9056 = 0.130 g of zeolite, which represents 13.0% per weight of slurry, crystallizes.

(We took several samples from the crystallization system, so we did not test the yield.)

An integral graph of the grain size distribution of the product, as determined by the sedimentation method, is shown in FIG. 3, from which the average grain size Φ is 1.45 pm.

A diffraction pattern of zeolite constructed using Cu Kα radiation is shown in FIG. 4. It is noteworthy, such as reflections of 2Θ = 23 ° (planes [533] at 2Θ = 23.5 °, reflection [642] / [246] at 20 to 26.9 °, planes [555] / [157] at 2Θ ~ 31.2 °) intensively, indicating long sections of the periodic grid arrangement.

If the grain size Φ = 1.45 pm is insufficient in this experiment, crystallization is continued after 3.2 hours with the second step.

Batch 1 currently has the highest crystallization rate.

After this time, the velocity slows because the amount of gel is greatly reduced (and thus also the amount of so-called secondary builders present in the solution is minimized, which is taken into account by function f (c)). This can be avoided by step lc of this procedure.

Performing a second synthesis

Adding a gel of substantially identical composition begins at the time of crystallization of the _AF i = 3.2 hours and leads to an increase in grain size.

However, this gel must not contain crystallization cores.

The gel of the following composition is uniformly added to the crystallization vessel for 1.5 hours.

1763.3 g of water glass with concentrations of 8.6 wt. % NaO and 28.0 wt. The SiO ₂ is diluted with 2600.0 h H2O.

1362.7 g of sodium aluminate with a concentration of 19.9% by weight and a molar ratio of Na ₂ O / Al ₂ O _{3 of} 1.58 are diluted with 2807.7 g of H ₂ O.

The two solutions are mixed together at the desired lower temperature (but at least at room temperature), with vigorous stirring.

The gel formed is used without aging.

The composition of the gel is as follows:

SiO ₂ A1 ₂ O3 Na ₂ O H ₂ O (mol) 3, 00 1.0 2,409 156,33

The absolute time is 3.2 + 1.5 = 4.7 hours. until the addition is complete.

Crystallization is continued for up to 7 hours to produce a product characterized by crystallinity identical to 1b as seen in the diffractogram of FIG. 5th

By subtracting from the graph the integral grain size distribution in FIG. 6, the average grain size is Φ = 2.45 pm.

Si / Al parameters = 1.32 and modulus m = 2.64 were determined by the AAS method.

Basic cell composition is:

Naa3 [A102) 83 (S1O2) 109] ~ 260 H2O so the difference is only 3.6% from the composition of NaX, which is considered typical.

The weight of the batch described above is 8584.4 g and 1158.0 g of zeolite can be produced.

If the grain size Φ = 2.45 pm is still too small, the third synthesis stage is approached at 7 am (absolute time is used in the calculation).

Performing a third synthesis

The gel used for the second synthesis was prepared in double the amount (weight 17168.8 g). Starting at seven o'clock, this gel is added in a similar manner to the slurry in the crystallization vessel for 1.5 hours. Crystallization is continued with slow stirring until ten hours. The crystals are then filtered off, washed and dried as in the previous procedures. Also, the diffractogram of FIG. 7 shows excellent crystallinity. Fig. 4 and 7 are almost identical.

Si / Al ratio defined by the method AAS (Si / Al = 1.31) the virtually unchanged. chart integral distribution size grain is a displayed FIG. 8, para inflexie je at Φ = 3.2 μιη. On the the higher described examples they can a flat

The following questions were answered:

(i) how much gel should be added to the batches (in grams or how many weight units per batch is needed) to achieve a predefined grain size Φ.

(ii) what addition rate should be maintained to ensure optimal crystallization rate.

The NaX zeolite (as well as NaY) crystallizes in the form of more or less distorted octahedral crystals in which the corner distance is characterized by their size.

Instruments based on the sedimentation principle and used to determine the integral particle size distribution make the choice of crystals not according to sedimentation rate.

crystal size equal corners distance,

If the obtained sedimentation hexaedric mass bias considering crystals, results in zeolite m for this

There is the following (g) either in or cluster of crystals using the octahedral principle or should not cause an excessive relationship between the crystal, the form of a single approximately equal size and the crystal size Φ (defined preferably in μπι):

(2)

The weight of the batch as a weight unit should be taken as the unit m, the average grain size Φ may be considered as a function of the quantity of batches.

It is known that Φι = 1.45 pm at m = 1, so according to (3)

Cl = = 1.45 for m = 2 Φ = 1.45 * V2 = 1.83 // ^ for m = 3 Φ = 1.45 * VI = 2.10 ///// for m = 4

Φ = 1.45 * V4 = 3.20 // ^ e r: '

A continuous curve constructed on the basis of these calculated points is shown in Figure 9.

Experimental values are denoted by »- _s (where m = 1 is the base point).

The values ané measured experimentally (by the sedimentation method) are higher than those calculated, but the decreasing characteristic of the measured increments ΔΦ confirms the function according to Vw ·

The inaccurate match of the curves may be due to different definitions of geometric dimensions and sedimentation dimensions, but the crystallizing slurry is probably not completely homogeneous and partially recrystallizes during crystallization.

In addition, due to the absence of shear, the crystals partially aggregate (as explained by the elongated tail of the sedimentation curve) and, as shown by electron micrographs, double crystals are formed by epitaxial overgrowth.

The most convenient way to determine m for the chosen Φ is to calculate using function (3), where the laboratory measurement data are taken as a basis and interpolated according to the theoretical relationship (m can of course also be a real value).

To produce Φ = 2,0 pm, m = 0,4 batch (0,4 * 8548,4 = 3419,4 g of slurry), to reach Φ = 3,0 pm it must be added to the first batch m Ξ 2,2 batch (2.2 * 8548.4 = 19661.3 g slurry).

At the same time, the function (2) describing the change in mass versus time means that the characteristic grain size Φ is a linear function of time:

Φ = A _o + Aiti = Aiti (ie dΦ / dt = Ai = const.) (4) because at t -> 0 Φ -> 0 (ie the core size is negligible).

If the velocity of the gel was not reduced due to the reduction of the gel amount, the crystal size may reach Φ = 1.45 μπι (analogous to the first batch) after 4.28 hours, according to the crystallization graph in FIG. 2. As a result

45 ^, = - = 0339 // ^ / ^ ¹ 4.28

According to (4) a grain size of Φ = 3.2 μιη, the crystallization time is 7.2 hours (in the case of unlimited growth).

The following proportionality exists between size Φ and mass m (where m can be the weight of a single crystal or any almost homogeneously dispersed conglomerate):

m ~ Φ ³ = Ai ³ t ³ = Bt ³ m = 1175.1 g after crystallization continued until ti = 4.28 hours (in the case of unrestricted growth), consequently and thus further

Practically for this reason

using

175.1 1175.1 (4.37) ³

1165.1

78.40 = 15.0 m = 15 * t ³ dm 2 - = 45.0 * / dt only 70% of this speed can be achieved, we can use the following formula:

- Ξ 32.4 * of ¹ df of the symbol M for the weight of the gel we can establish a simple relation:

\ t dm / 32.4 M / ² ₂ - = - = ---- = ^240/2 Aďt dt between 0.135 dm / dt and the rate of addition of the gel dM / dt.

As a result, the gel should be added at a rate increasing with the square of time t in order to maintain an optimal crystallization rate. This condition cannot be met for most existing pumps.

dM / dt is in the illustrative graph of FIG. 10 shown as function t.

Area under the curve, t. j. the integral dM / dt from t = 3.2 hours to t = 7.2 hours is the same as the weight of three batches (3 * 8584.4 g = 25753.2 g).

If only one pumping rate is used, dosing is performed at the rate

During the first two hours, however, it allowed to use the feeding rate of less than wo and a higher feed rate than w ₀ for the other two hours.

If the graph dM (t) dt is expressed in exact circumstances, the time of change from slower to faster pumping speed can be easily calculated. However, the accuracy of the graph is only approximate, so for the first two hours the pumping rate wi = 4200 g / h (weight of added gel is 8400 g) must be selected and the remaining amount of 17353 g is dosed at:

which is approximately twice as fast for the next one hour.

The dosing speed can easily be doubled using two pumps.

This principle clarifies about twice the feed rate in the third synthesis.

Example 2

The aim is to produce a mixture of NaA-NaX zeolites with an average grain size of Φ = 8 to 9 μπι and with a high ability to bind calcium and magnesium ions in ion exchange reactions.

Preparation of solution A, initiation of crystallization

4800 g of 8.9% waterglass solution

weight. At ₂ 0 % and 28.1 wt. The SiO ₂ is mixed with 4850 in the vessel g H ₂ O a 1000 g NaOH with a concentration of 45.17 wt. IN another container 9000 g of aluminate are mixed sodium with molar ratio 1.5 Na ₂ O / Al ₂ O ₃ and concentration 15.8 % weight. with 4850 g H ₂ O and 1000 g NaOH with concentration 45.17 % weight.

Then, the two solutions are mixed together by vigorous stirring, and crystallization is initiated at 25 ° C.

The molar ratios are as follows:

SiO ₂ A1 ₂ O ₃ Na ₂ O H ₂ O (mol) 2.64 1.0 3, 65 114.74

Preparation of solution

1493 g of a 8.9% by weight aqueous glass solution. % Na ₂ O and 28.1 wt. SiO ₂ is mixed in the vessel with 177 g solid NaOH dissolved in 360 g H ₂ O.

In another vessel, 433 g of sodium aluminate is mixed with a Na ₂ O / Al ₂ O ₃ molar ratio of 1.5 and a NaOH concentration of 15.8% by weight. 177 g of solid NaOH dissolved in 360 ml H ₂ O.

Finally, the two solutions are mixed by vigorous stirring to obtain solution C with the following molar ratios:

SiO ₂ A1 ₂ O ₃ Na ₂ O H ₂ O (mol) 13, 63 1.0 14.31 224.91

To perform crystallization:

Solution C was added to solution A, which crystallized with vigorous stirring for 1 hour and the temperature was raised to 60 ° C.

After 3 hours, the temperature is raised to 80 ° C and crystallization is continued after addition with slow stirring for 6 hours.

Filtration and washing

The zeolite crystals were filtered through a Buchner funnel and washed with condensed water to pH <10.

Composition of the product obtained:

parameter Measured value Meramia method NaX% 91 XRD PW 1710 NaA% 9 XRD PW 1710 SiO2 / Al2O3 molar ratio 2.37 Gravimetry, titration CaO ion exchange capacity mg / g 138 Complexometry MgO ion exchange capacity mg / g 85 Complexometry Average grain size Φ pm 8.7 Laser diffraction, CILAS 1064 Collection of surfactants ml / 100 g 200 Modified standard DIN-ISO 787/5 BET nc / g 47 GEMINI Z 370

Thereby a zeolite filler is obtained, which is well applicable to modern washing powders.

Example 3

The aim is to produce a type X zeolite with a high surfactant and Ca and Mg ion binding capacity, with an average grain size of Φ = 4 to 6 μιη and a SiO ₂ / Al ₂ O ₃ molar ratio = 2.45.

Preparation of solution A, initiation of crystallization

4700 g of a 8.9% by weight aqueous glass solution. % Na ₂ O and 28.1 wt. SiO ₂ is mixed in the vessel with 5400 g H ₂ O and 100 g NaOH solution with a concentration of 45.17 wt.

In another vessel, 9500 g of sodium aluminate are mixed with a Na ₂ O / Al ₂ O ₃ molar ratio = 1.62 and a NaOH concentration

15.5 wt. with 5400 g H ₂ O and 100 g NaOH solution with a concentration of 45.17 wt.

Then the two solutions are mixed together by vigorous stirring and crystallization is initiated at 25 ’C.

The molar ratios are as follows:

SiO ₂ A1 ₂ O ₃ NčijO H ₂ O (mol) 2.63 1.0 2.77 127.66

Preparation of solution

1515 g of a 8.9% by weight aqueous glass solution. % Na ₂ O and 28.1 wt. SiO ₂ is mixed in a vessel with 113 g solid NaOH dissolved in 1573 g H ₂ O.

In another vessel, 114 g of alkaline aluminate with a molar ratio of Na ₂ O / Al ₂ O ₃ = 1.62 and a concentration of NaOH are mixed

15.5 wt. with 112 g of solid NaOH dissolved in 1572 g of H ₂ O.

Finally, the two solutions are mixed by vigorous stirring to give solution C.

The molar ratios are as follows:

SiO ₂ A1 ₂ O ₃ Na ₂ O H ₂ O (mol) 53,87 1.0 39, 54 1,788.93

To perform crystallization: solution C is added to solution A, which at intensive stirring for 1 hour crystallized and temperature the will increase to 60 ° C Mon 3 hours the temperature is raised to 80 ’C and crystallization continued at this temperature 6 hours at

stirring slowly.

Filtration and washing

The zeolite crystals were filtered through a Buchner funnel and washed with condensed water to pH <10.

Composition of the product obtained:

parameter Measured value Meramia method NaX% 100 XRD PW 1710 SiO ₂ / Al ₂ O ₃ molar ratio 2.45 Gravimetry, titration CaO ion exchange capacity mg / g 132 Complexometry MgO ion exchange capacity mg / g 69 Complexometry Average grain size Φ pm 6, 6 Laser diffraction, CILAS 1064 Collection of surfactants ml / 100 g 145 Modified standard DIN-ISO 787/5 BET n / g 6.5 GEMINI Z 370

Thereby a zeolite filler is obtained, which is well applicable to modern washing powders.

Example 4

The aim is to produce a mixture of NaA and NaX zeolites with good ion-exchange properties for Ca and Mg ions, with an average grain size of Φ = 15 to 20 µm.

Preparation of solution A, initiation of crystallization

4700 g of a 8.6% wt. % Na ₂ O and 27.4 wt. SiO ₂ is mixed with 4800 g H ₂ O and 850 g NaOH solution with a concentration of 45.17 wt.

In another vessel, 10200 g of sodium aluminate are mixed with a Na ₂ O / Al ₂ O ₃ molar ratio = 1.65 and a NaOH concentration of 15.05 wt%. 4800 g H ₂ O and 850 g NaOH solution with a concentration of 45.17 wt.

Then, the two solutions are mixed together by vigorous stirring, and crystallization is initiated at 30 ° C.

The molar ratios are as follows:

SiO ₂ A1 ₂ O ₃ Na ₂ O H ₂ O (mol) 2.63 1.0 3.71 120.45

Preparation of solution

2070 g of a 8.6% wt. % Na ₂ O and 27.4 wt. SiO ₂ is mixed in a vessel with 245 g solid NaOH dissolved in 500 g H ₂ O.

In another vessel, 600 g of sodium aluminate is mixed with a Na ₂ O / Al ₂ O ₃ molar ratio = 1.65 and a NaOH concentration of 15.05 wt%. with 245 g of solid NaOH dissolved in 500 g of H ₂ O.

Finally, the two solutions are mixed by vigorous stirring to give solution C.

The molar ratios are as follows:

SiO ₂ A1 ₂ O ₃ Na ₂ O H ₂ 0 (mol) 15.0887 1.0 16, 01 257.899

To perform crystallization:

% of solution C was added to solution A, which crystallized with vigorous stirring for 1 hour, then crystallized.

% of solution C is added to the previous slurry in the second hour of crystallization with vigorous stirring and the temperature is raised to 60 ° C.

After 3 hours, the temperature was raised to 80 ° C and crystallization was continued at this temperature for 6 hours, with slow stirring.

Filtration and washing

The zeolite crystals were filtered through a Buchner funnel and washed with condensed water to pH <10.

r r

Composition of the product obtained:

parameter Measured value Meramia method NaX% 68 XRD PW 1710 NaA% 31 XRD PW 1710 SiO ₂ / Al ₂ O ₃ molar ratio 2.28 Gravimetry, titration CaO ion exchange capacity mg / g 47.3 Complexometry MgO ion exchange capacity mg / g 80.2 Complexometry Average grain size Φ pm 17.9 Laser diffraction, CILAS 1064 Collection of surfactants ml / 100 g 125 Modified standard DIN-ISO 787/5 BET m ² / g 18 GEMINI Z 370

A special zeolite is thus obtained, which can be applied as a large-size molecular sieve.

Claims (10)

PATENT CLAIMS A process for producing synthetic NaX, NaY zeolites or mixtures thereof, or mixtures thereof with NaA zeolites, from sodium aluminate and water glass solutions, characterized in that: (a) a gel containing: 1.5 until 5.3 M SiO ₂ / l M A1 ₂ O ₃ 1.5 until 2.5 M Na ₂ O / l M ai ₂ o ₃ 88 until 260 M H ₂ O / 1: M ai ₂ o ₃ pH maximum = 13.2 is prepared by intensive mixing of a mixture of sodium aluminate solution, water glass and water - solution of glass and water of synthetic solutions A-, a mixture of aqueous-solution B- and vigorous mixing of the core solution formed by vigorous mixing and B, the gel formed at the highest point -tinfi ^- , then the gel of crystals, without synthetic cores and with ratio limits identical to or several doses of slow agitation is added, and if to increase the size of slow agitation crystallization to increase the molar with the original gel, in one and crystallization takes place as desired the addition of the gel gel and the subsequent crystallization are repeated one or more times and then the crystals obtained are separated, washed and dry by known methods, or (b) solution A of composition 2.0 to 5.3 moles SiO2 / mole of A1 ₂ O ₃ 2.5 to 7.5 moles of Na ₂ O / l moles of Al ₂ O ₃ 88 to 260 mol of H ₂ O / 1 mol of Al ₂ O ₃ pH maximum = 13.3 is prepared by intensive mixing of sodium aluminate solution, water glass solution, the gel formed crystallizes with slow stirring until the composition is reached 2.0 to 100 moles _SiO2 / mole of A1 ₂ O ₃ the maximum crystallization rate, then a solution of C 2.5 to 100 moles Na ₂ O / l mol Ä1 ₂ O ₃ 88 to 5000 moles of H ₂ O / 1 mol of Al ₂ O ₃ , formed by vigorously mixing a solution of sodium aluminate, water glass and distilled water in one or more portions into a mixture containing crystals followed by crystallization in one or more steps until the desired size The crystals produced are separated, washed and dried according to known methods. Process variant (a) according to claim 1, characterized in that the crystal size-increasing gel is added continuously in a uniformly accelerated manner. Process variant (a) according to claim 1, characterized in that the crystallization is carried out at a temperature of 88 ± 2 ° C. Process variant (b) according to claim 1, characterized in that the first crystallization step is carried out at a temperature of 22 to 30 ° C, followed by a subsequent step at a temperature of 60 to 80 ° C. Process variant (b) according to claim 1, characterized in that solution C is added in a single dose. Process variant (b) according to claim 1, characterized in that solution C is added in several portions. Synthetic zeolites or mixtures thereof according to variant (a) or (b) of claim 1, characterized in that the average particle size of the zeolites is at least 1.0 μιη, preferably 1.0 to 20.0 μιη. 8th Zeolites or mixtures thereof according to claim 7, in that the average particle size of the zeolites is 9th The zeolites or mixtures thereof according to claim 1, wherein the average particle size of the zeolites is 10th Zeolites or mixtures thereof according to claim 7, in that the average particle size of the zeolites is indicative 3, 2 μιη. characterized 8,7 μιη. characterized 17,9 μιη.