FI66130C - SYNTHETIC FINISHED CRYSTALS SILICONE ALUMINUM FOUNDARY FOAR DESS FRAMSTAELLNING SAMT DESS ANVAENDNING - Google Patents

Description

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France-Frankr i ke (FR) (72) Max Michel, Yerres, France-Frankrike (FR) (7 * 0 Berggren Oy Ab (5 * 0 Synthetic finely divided crystalline silica aluminate, method of preparation and use - Syntetiskt finfördelat kristalini si 1, the same number as in the case of paragraph 11 of this Regulation

The present invention relates to a novel synthetic, finely divided, crystalline silicoaluminate and to a process for its preparation and use in purification.

The general method of preparation of synthetic aeolites has long been known (Kurnakow, Journal de 1'Academie des Sciences d'URSS, 1381 (1937)). According to this method of preparation, the silicate solution and the aluminate solution are contacted so as to obtain a gel on which crystallization occurs.

The formation of these silicoaluminates depends on a large number of factors such as the concentration of the reactants, the contact temperature, the temperature of the ripening step, the duration of the ripening and the homogeneity of the reaction medium. Methods such as inoculation have also been used to obtain silicoaluminates with defined properties, for example with faujasite in a reaction medium which already contains a 4 A type zeolite according to French patent application 2,281,315.

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The presence of certain factors, and in particular sodium oxide, and the effect of alkalinity on the reaction medium have already been proved by Kurnakow.

French Patent 1 404 467 points out that the Na content of the liquid medium in which the silicoaluminate precipitate occurs is decisive for the regularity and crystal purity of the 4A zeolite obtained and that the better this content is maintained | as standard, the better the purity and homogeneity of the zeolite.

Compared to recent times, the proposed methods have been batch-type. This situation has been explained by emphasizing the complex structure of the crystals, which usually require a relatively long time to form, starting from irregular and randomly distributed compounds in the liquid and solid phases of the reaction mixture.

It is for this reason that U.S. Pat. No. 3,071,434 proposes to improve the formation kinetics of 4A-type zeolites by seeding the mixture with a slurry recycled back from a point downstream of the reaction zone.

However, this method has been criticized for its difficulty in performing U.S. Patent 3,425,800, which proposes the use of a three-layer crystallizer in which a cold-precipitated gel suspension is heated to 100 ° C and then fed to a crystallizer where crystalline silicoaluminate is formed. According to this method, crystalline silicoaluminate is recovered by decantation.

French Patent Application 2,096,360 proposes the avoidance of passage by a multi-step process comprising preheating an aqueous solution of sodium silicate to approximately the precipitation temperature and adding it hot to the aluminate solution, which is also maintained at the precipitation temperature.

The products thus obtained have mostly been valued for their very good absorbency, which selectively affects the molecules depending on their size and shape, which is why they are commonly referred to as "molecular sieves".

However, the use of these types of products has also been considered due to their other properties, in particular their cation exchange capacity. One of the most common uses in this area is the use of these compounds in cleaning compositions.

3,661 30

In fact, it has been known since biblical times to include silicoaluminate-based derivatives in cleaning products. However, interest in this possibility has greatly increased since, on the one hand, the leading role of sodium tripolyphosphate as a cleaning agent has been shaken by its contamination effect and, on the other hand, reliable and reproducible progress has been made in the production of silicate aluminates.

Cleaning aids such as sodium tripolyphosphate act in many ways and especially as cation exchangers. Since silicoaluminates also have this property, it was therefore natural to consider their use, especially when there was no need to look out for them at an ecological level.

Recently, various types of silicoaluminates, usually crystalline, have also been proposed, which are characterized by a high cation exchange capacity and / or a high exchange rate.

Unfortunately, these silicate aluminates have two disadvantages. First, they cannot completely replace sodium tripolyphosphate because they do not appear to act in the detergent environment other than as cation exchangers, instead the effect of sodium tripolyphosphate is more versatile and especially dispersing and complexing. In addition, these silicoaluminates are insoluble, which manifests itself as a phenomenon called incrustation or mineralization, which results in the deposition of said silicoaluminate particles on the fabric, especially cotton.

It has been thought that the inlay phenomenon could be reduced by using fine granulometry. But in reality, the effect of granulometry on the cleaning ability and especially on the inlay phenomenon is so far poorly known.

It is simply stated that the particles must be well identified. More specifically, with respect to the replacement of sodium tripolyphosphate with alkaline silicoaluminate, it is found that the more critical the relative amount of tripolyphosphate relative to the amount of silicoaluminate, the more critical the operating conditions.

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However, a new type of crystalline, finely divided, well-dispersed sodium silicoaluminate corresponding to the general formula x SiO 2> yAl 2 O 3, z Na 2 O, wH 2 O where y = 1, x = 1.5 to 6, z = 1 and w = 0 * 5 has now been invented.

Preferably, this silicoaluminate corresponds to the formula where x = 1.85, y = 1, w = 4 to 5 and z = 1 and is of type 4 A.

Microscopic examination reveals the existence of small individualized cubes with a particle size substantially between 0.2 and 8 u u and a large specific surface area between 0.5 and 10 mVg.

The silicoaluminates according to the invention have very specific particle sizes over a wide range of average particle sizes, which makes them suitable for use in a variety of applications such as detergents, binder drying and separation.

In the case of use in purification, it is stated that it is necessary to select a silicoaluminate according to the invention having a small particle size, namely 0.2-3 μm, a high specific surface area, namely 1-10 mVg, and high cation exchange capacity and exchange rate.

Such a silicoaluminate is particularly well suited for use in cleaning, where it has properties that can withstand comparison with the best known silicoaluminates, but where its inlay ratio is considerably lower.

This novel silicoaluminate of the present invention can be produced by a batch process, but in practice it is preferable to use a continuous process.

The method according to the invention is generally characterized in that the gelation step takes place in a thick and homogeneous environment.

Preferably according to the present invention: a sodium aluminate solution is first formed, this solution is cooled to below ambient temperature, sodium silicate solution is added, stirring so as to keep the environment homogeneous, the temperature is raised to between 60-100 ° C, allowing the environment to gel, this temperature is maintained for a period of 0.2 to 5 hours until the silicoaluminate formed in the suspension state is completely dispersed again.

Preferably, the starting mixture consists of a sodium aluminate solution cooled to a temperature between -10 ° C and + 10 ° C and a sodium silicate solution at an ambient temperature substantially above 10 ° C.

The mixing is carried out with stirring, with the aid of any suitable device, by which the medium is homogenized in a time shorter than the gel time of the mixture at the equilibrium temperature of said mixture. This time is preferably less than 15 minutes.

The concentrations of the two reactants are chosen so that at the end of the development a liquid phase with a titer of at least 70 g / l Na2O and 10 g / l Αΐ2Οβ is obtained, in equilibrium with at least 200 g / l molecular sieve.

In the case of a small particle size of 0.2-3 μm, the concentrations of reactants are chosen so that at the end of the evolution a liquid phase with a titer of at least 100 g / l Na 2 O and 30 g / l Αΐ2Οβ is obtained at equilibrium at least 200 g / l molecular sieve, while for a larger particle size, a liquid phase with a titer of less than 100 g / l, preferably 70-100 g / l Na 2 O and less than 30 g, preferably 10-30 g / l Al 2 O-j is preferably selected. .

It is obvious that the process according to the invention can be carried out as a batch process; but it has the advantage that it can be performed continuously.

In practice, proceed as follows: 6 66130

First, mixing of the sodium aluminate solution cooled to said temperature range and the sodium silicate solution at approximately ambient temperature is performed, before the gel is formed, the mixture is sprayed into a first zone having a density lower than the density of the aqueous mixture and heated to a temperature the first zone is formed by a non-water-miscible carrier such as oil or kerosene bath, the temperature is maintained in the second downstream zone in the bath until the transition to the crystalline phase is complete, while ensuring piston-like progression to this downstream zone, silica-aluminate crystals, said crystals being separated from the suspension by any known means such as filtration or centrifugation, washed and taken I recover.

Preferably, the first zone is the deposition zone, where the reaction mixture is subjected to agitation for a very short duration, 1-2 seconds, while the second zone is the piston propagation zone and corresponds to a much longer residence time.

As mentioned above, the products of the present invention are suitable for use with a particular yeast in cleaning compositions, although this use is in no way limiting.

However, the present invention will be more readily apparent from the accompanying drawing and the following examples, which are given by way of illustration only and not by way of limitation.

In order to better demonstrate the properties of the product according to the invention, comparative experiments have been performed with known products and the following tests have been used:

Particle size distribution: This was performed using a Coulter calculator selecting the following solution (wt%) as the electrolyte: 66130 water 78% glycerol 20%

NaCl 1%

Na-hexametaphosphate 0.5% formol 0.5%

Dispersion for 2 minutes (ultrasound) - 40,000 Herz - 100 watts. Cleaning power:

The cleaning efficiency has been demonstrated in washing experiments at 90 ° C with cotton samples soaked in normalized dirt prepared by the Waschereiforschungsinstitut Krefeld.

The experiments were performed on a LINITEST instrument (manufactured by Original Hanau). Two soiled samples (4.2 g) and two uncontaminated cotton samples (4.2 g) and 100 ml of cleaning solution having the composition shown below were placed in each vessel. Washing was followed by four consecutive 30-second rinses.

Water with a hardness of 28.5 ° TH was used. The cleaning mixture used in a ratio of 9 g / l was as follows: alkyl benzene sulfonate LAB 5.3% non-ionic (C 16/14 OE) 2% sodium stearate 2.8% sodium tripolyphosphate 4.2% sodium silicoaluminate 45% perborate 22.1% sodium silicate 2.5% carboxymethylcellulose 1.2% magnesium silicate 1.7% sodium sulfate 2.1% H 2 O 100% The reflectance of the samples was measured before and after washing with a photoelectric photometer Elrepho (trade name Zeiss), using filter 6.

Incrustation effect A mixture having the following composition was used: 8,661 30 silicoaluminate 2.4 g / l sodium tripolyphosphate 1.6 g / l LAB (alkylbenzenesulfonate) 0.8 g / l ethoxylated alcohol (cSmulsol DB 25/17) 0.4 g / 1 sodium stearate 0.4 g / l sodium sulphate 0.8 g / l

Washing was performed on a Lini Test instrument. Cotton samples (the cotton used was manufactured by TEST FABRICS INC., Reference Bleached Cotton Sheeting, Style 405) measuring 10 x 12 cm each received 450 cm 3 of the solution described above. The water hardness was 30 ° TH. (NFT 90 003).

The actual washing was performed at 60 ° C and lasted 35 min (25 min temperature rise + 10 min at 60 ° C).

Two rinses were then performed, one rapid rinsing for about 1 min in 350 cm of water, the other a slow, 5 min rinsing in 450 cm of urban tap water (30 ° TH).

Drain and dry.

Finally, cotton samples were calcined at 900 ° C for 2 hours. The ash was collected and weighed.

It is appropriate to add to these tests the tests for the product itself: specific surface area exchange rate.

Example 1 1 liter of sodium aluminate solution with a titer of 200 g / l Na 2 <3 and 200 g / l Al 2 O 3 is cooled to 4 ° C in a round-bottomed flask.

0.4 l of sodium silicate solution at a temperature of 20 [deg.] C. and a titer of 25.3% by weight of H2O and 7.42% of Na2O are then added with vigorous stirring so that the mixture remains homogeneous at all times. At the end of the addition, the temperature is raised to about 15 ° C, at which point the reaction mixture is still quite fluid. Stirring is stopped and the temperature is allowed to rise close to ambient temperature, causing the reaction mixture to form a gel. The round-bottomed flask is then kept in a water-thermostat set at 83 ° C for 2 hours; at present, the rigid mass of the original gel has been transformed into a suspension of microcrystals, which is dried by centrifugation and washed continuously with a filter wall with a central orifice size of 1 micron. The amount of crystalline silicoaluminate contained in the microcrystalline suspension is about 320 g / l. The washed cake is then dried to constant weight in an oven at 100 ° C before analysis.

The dried and analyzed zeolite essentially corresponds to the formula: 1.85 SiO 2, 1 Αΐ2θ3, 1 Na 2 O, 3 H 2 O.

As determined by X-rays, it turns out to have the structure of a 4A-molecular sieve.

The electron microscope detects very small, individualized cubes with a uniform particle size and smaller than a micron or order of micron size, well distributed, as shown in Figure 1 at 4500x magnification.

The specific surface area BET is equal to 7 m2 / g.

For comparison, the following experiment 2 was performed:

One liter of sodium aluminate solution with a titer of 74 g / l Al 2 O 3 and 127 g / l Na 2 O was heated to 83 ° C with good stirring in a round bottom flask.

0.271 L of the silicate solution obtained by diluting 50 ml of a commercial sodium silicate solution with a titer of 477 g / l and 239 g / l Na 2 O was then rapidly introduced. After the temperature rose again to 83 ° C, the mixture was kept at the level for 2 hours, stirring constantly. The crystal suspension was then dried by centrifugation and washed on the filter without special precautions. The washed cake was then dried and analyzed as in the previous example.

The dried zeolite corresponds to the formula: 1.85 SiO 2, 1 Al 2 O 3, 1 Na 2 O, 3.8 H 2 O By X-rays, its structure is found to be the structure of a type 4A molecular sieve, the appearance of which is shown in Figure 2 (magnification 4500 x).

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The electron microscope detects micron-sized, fairly well-identified cubes with a wide particle size distribution (1-5 microns). The specific surface area BET is equal to 1.2 m 2 / g.

The powders of Experiments 1 and 2 are subjected to a Nai == * Ca ion exchange rate test as follows: 1 g of a dried powder with a temperature of 100 ° C and an annealing loss at 1000 ° C of 19% is placed in 1 liter of a solution containing 594 mg of Cl2Ca In 1 minute by means of an ultraturax turbine with a speed of 9000 rpm and equipped with a T 45 K top. After dispersion, the suspension is kept under a magnetic stirrer for 1 minute, 4 minutes and 14 minutes before being rapidly (20 seconds) evacuated by vacuum centrifugation on a RAWP 047 millipore filter to analyze the amount of Ca 2+ ions Ca ions remaining in solution.

The following results are obtained, which show that the very finely divided silicoaluminate according to the invention has a clear exchange kinetic advantage: the exchange rate of 2+ MEQ / G Ca ions is MEQ / G sec. per after 2 min after 5 min after 15 min

Experiment 1 4.9 5.12 5.3

Experiment 2 2.1 3.2 4

Theoretical ability 5.8.

cleaning power

Reflectivity before Reflection after washing

Silico aluminate according to the invention 39.4 59.1

Comparison 39.3 60.7

It is stated that the cleaning efficiency is essentially the same.

Inkrustaatiovaikutus

Results as% by weight of tissue

According to the invention 0.35%

Comparison 0.9% A fairly clear difference is observed here.

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Example 2

A 4A type silicoaluminate having the same properties as described in Example 1 is prepared using a continuous process according to which the invention can be used in industry (see Figure 4).

A sodium aluminate solution with a titre of 200 g / l Na 2 O and 200 g / l Al 2 O 3 is cooled to -4 ° C in a tubular heat exchanger at a rate of 1 to 10 liters per hour. The cooled stream is continuously stirred in a stream of 4 l / h 3 sodium silicate solution at a temperature of 20 ° C and a titer of 25.4% SiO 2 and 7.42% Na 2 O by weight in a stirred reactor 2.

A homogeneous mixture with a temperature of about 15 ° C is fed by a screw pump 4 to a jet 5 with 0.5 mm diameter capillaries, which continuously forms droplets which fall on the top of the reactor 6 filled with kerosene, the temperature of which is maintained at 85 ° C. by circulating heated salt water 7.

The density of the bath is set so that the average falling time of the droplets formed by the capillaries is 3 seconds. After this time, the spherical particles gel and accumulate on the grid 8 located at the bottom of the reactor and gradually turn into a flowable silicoaluminate suspension which collects in the conical part 9 of the reactor 6. This suspension is continuously sucked out by a suction tube 10 1 hour, so that the average residence time of the reactants in the reactor becomes 1 hour.

the aspirated suspension is then dried by centrifugation and washed in any known manner.

Example 3

Proceed as in Example 1, except that 0.6 l of silicate solution is added instead of 0.4 liters.

This gives a silica aluminate suspension with a consistency of about 450 g / l.

It is observed that the average particle size of the silicate aluminate is larger, as shown in Figure 3, where the magnification is 4500 times.

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Example 4

A 4 A-type silicoaluminate according to the invention is prepared using the continuous process shown in Figure 4, which enables the industrial application of the invention.

A sodium aluminate solution with a titre of 110 g / l Na2 <3 and 150 g / l Al2O3 is cooled to 0 ° C in a tubular heat exchanger at a rate of 1 to 10 liters per hour. The cooled stream is continuously stirred in a sodium silicate stream at a rate of 4 1 / h and a temperature of 20 ° C with a titer of 25% by weight SiO 2 and 11.6% by weight Na 2 O in a stirred reactor 2.

The homogeneous mixture, which has a temperature of about 12 ° C, is fed by a screw pump 4 to a jet 5 with 0.5 mm diameter capillaries, which continuously forms droplets which fall into the top of the reactor 6 filled with kerosene maintained by circulating brine heated at 85 ° C.

The density of the bath is set so that the average falling time of the droplets formed by the capillaries is 3 seconds. After this time, the spherical particles gel and accumulate on the grid 8 at the bottom of the reactor and gradually turn into a fluid silicoalurinate suspension which collects in the conical part 9 of the reactor 6. This suspension is continuously sucked out of the suction pipe 10 at a rate of hours so that the average residence time of the reactants in the reactor becomes 2 hours.

In this example, the crystalline sodium silicoaluminate of the microcrystalline suspension has a consistency of about 340 g / l, and the titer of the liquid phase, which is practically free of SiO 2, is 76 g / l Na 2 O and 12 g / l Al 2 O 3. The resulting microcrystalline suspension is dried by centrifugation and washed with a filter medium having an average hole size of 1. The washed cake is then dried to constant weight in an oven at 100 ° C before analysis.

The resulting product, type 4 A, has a homogeneous particle size and an average of 3-4 and is well distributed as shown in Figure 5 (magnification 4500 x). The specific surface area BET of the product is 1 m 2 / gl 13 661 30

The ion exchange

2+

Amount of exchanged Ca ions MEQ / G sec after 2 min after 5 min after 15 min 4.2 4.7 5.3

The following table shows the particle sizes according to Coulter after drying with the control sample, the product of Example 2 and the product of Example 4.

Comparative sample Eg 2 Eg 4 l ^ u smaller particles 0 20 2 2 yU "12 68 20 5 yU" 87 95 92 10 yU "95 98 98

Mean particle diameter ^ u 3 1.5 3

It is observed that on the one hand smaller particle sizes can be obtained and on the other hand with the same average particle size the particle size distribution is different.

The inlay ratios are shown in the following table:

Average Example 2 Example 4 1 wash 0.3 0.15 0.25 10 wash 1.0 0.45 0.9

Claims (7)

A process for preparing synthetic crystalline silicone aluminate by adding in an alkaline aluminate solution an alkaline silicate solution, ripening at elevated temperature and then separating the obtained silicoaluminate crystals, characterized by forming a mixture of a sodium aluminate solution, a temperature below ambient temperature, and a sodium silicate solution, whereby the environment is poured homogeneously, and the homogeneous environment is caused to form a gel by raising the temperature to 60-100 ° C, the concentrations of the two reagents being such that the concentration of the silica aluminate in the environment , when the development ceases, is at least 200 g / liter. Process according to claim 1 for the preparation of silico-aluminate, characterized in that the initial mixture consists of a sodium aluminate solution cooled to a temperature between -10 and + 10 ° C, and a sodium silicate solution having the ambient temperature. Process according to claim 1 or 2 for the production of silicoaluminate, characterized in that the homogenisation of the environment is carried out by stirring for a time shorter than 15 minutes. Process according to any one of claims 1-3 for continuous preparation of crystalline silica aluminate, characterized in that - first mixing a sodium aluminate solution cooled to a temperature below ambient temperature with a sodium silicate solution - spraying this mixture before gel formation in a first zone, which is constituted by a water immiscible heating environment, the density of which is less than the density of the aqueous mixture and which is heated to such a temperature that said aqueous mixture assumes the developmental temperature of the reaction so that a heat transfer occurs, - in the bath, this temperature in a second downstream zone until development ceases; at the same time, a piston-like forward progression is secured into this downstream zone,