DD152525A1 - PROCESS FOR THE PRODUCTION OF ALUMOSILICATES - Google Patents

Abstract

The invention relates to a process for the preparation of semicrystalline and crystalline aluminosilicates of the zeolite type A, wherein the invention relates to a technically simple to carry out process. According to the invention, the continuous reaction of sodium aluminate and sodium silicate solution is carried out by heating starting materials to the reaction temperature and passing them successively through two or more stirred containers, whereby certain ratios of the stirring intensities and volumes of the stirred containers are to be maintained. The aluminosilicates prepared by the process according to the invention can be used as ion exchangers, adsorbents, catalysts, catalyst carriers and for the preparation of suspensions or as thickeners.

Description

223 336 - * -

OF THE INVENTION: Process for the preparation of aluminosilicates

Field of application of

The present invention relates to a process for the preparation of partially crystalline and crystalline aluminosilicates of the type zeolite A, which as a water softener, ion exchange, drying, and adsorbents and as Trä ~ ger,? J, B _e for heterogeneous catalysts find application "

Characteristic of the known technical solutions

Semicrystalline and crystalline aluminosilicates of the type zeolite A having the general formula

° 3 · y ^Si0

in the anhydrous state, where χ numbers between 0.85 and 1.2, y can take between 1.7 and 2.25, are now produced by multi-stage process, which are designed mainly discontinuous. In this case, first of all, an aqueous aluminosilicate and sodium silicate solutions which contain sodium hydroxide in excess, based on the above formula, are used to prepare a sodium aluminosilicate gel. Thereafter, one after the other in separate vessels aging of the gel and after heating to temperatures of 90 to 100 ⁰ G, the crystallization sum desired zeolite A.

This procedure requires a large temporal and apparative Aufv / and compliance with many physical and chemical 'parameters * There are numerous proposals to reduce the expenditure on equipment, the required reaction time and in particular to reduce crystallization time and

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to make the procedure as continuous as possible

In the case of discontinuous processes, this should be achieved inter alia by heating the starting materials and preparing the aluminosilicate gel "at the crystallization temperature (DT-OS 2,127,754, 2,329,481) by using a specially designed column for the mixing of aluminate and silicate solution (DD-WP 107 428) by the addition of seed crystals (J _e L. Guth, "Caullet and R. Wey, Bull Soc Chim JJHS" 2375) or with partial recycling of end product, for example, mother liquor (US Pat 434, DOS 2 633 304, 2 744 784, 2 824 342).

Continuous processes require specially constructed apparatus in which the individual process stages; Run mixing of the starting materials, gelation, aging and crystallization in a reactor and is ensured by partial backmixing for the constant presence of a sufficient number of seed crystals (DD-YIP 138 968, 132 069). Other proposals are based on the use of specially designed mixing devices (DD-WP 107 428) or on the use of a further phase in which crystallization and separation into zeolite A and mother liquor takes place (US Pat. No. 3 425 800).

The use of semi-crystalline or crystalline zeolite J in detergents requires products with very small grain sizes (<5 / To) "^ ¹ Ur the production of aluminosilicates of zeolites A with these small grain sizes is the use of high shear proposed (D2 ~ 0S 2333 068, 2 517 218, 2 704 310, 2 734 296). However, this leads to the partial destruction of the crystal structure, whereby the ion exchange and adsorption properties are impaired.

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All of these proposals are only suitable for the preparation of aluminosilicates of zeolite A having certain desired physicochemical properties, e.g. high CaO-Bindevermogen, a relatively narrow range of grain or a high Y / assera & sorp ti ons assets, but not with all-round optimal application properties "Of Lachteil here is the use and the necessary construction of special equipment, which is costly · Furthermore, the formation of unwanted zeolite phases or Recrystallizations in the proposed embodiments can not be ruled out *

In DS-OS 2,127,754, one or more stirrers connected in series are finished in a purity of 90 to 95 % for the production of crystalline aluminosilicate of the zeolite type A. In this case the starting materials sodium aluminate solution and sodium silicate solution are mixed in compliance with certain conditions, essentially the already known molar ratios of ifa ₂ 0 / ill ₂ 0 ₃ , Ua ₂ 0 / Si0 ₂ and ITa ₂ OZAl ₂ O- + SiO ₂ . and the resulting sodium aluminum silicate crystallizes in the same vessel under high shear forces. " It is also possible to divide the reactor volume into two stirred vessels of different stirring intensity, so that mixing of the output products and partial reaction takes place in the first vessel, which is completed in the second vessel. In the cited patent specification, it is essential to maintain a constant temperature with ± -5 ⁰ C deviation considered for a continuous procedure. The occurrence of non-crystalline materials or in the form of Fehlkristallisaten Hydroxisodalith is entgeg closely ewirkt by lengthening or shortening of the duration of precipitation, "but not in the entire area in the indicated molar ratios, a continuous production of aluminosilicate with a ge ~ en Eristallinitätsgrad wished possible. In particular, the description of the agitation intensity in or on the successive agitation vessels and the tuning of the molar ratios

22333.6

Na ₂ OZAl ₂ O-, Ha ₂ 0 / Si0 ₂ , H ₂ 0 / Ha _o 0 and AlgOySiOg in the Ausgangslösimg s with the required reaction times or residence times in discontinuous or continuous processes insufficient ^ s is possible in that with too high alkali content and long reaction times, the patent specifies 45 minutes to 10 hours, is operated at high stirring intensities, whereby the formation of hydrozisodalite and other Fehlkristallisaten is favored. Details about the stirring intensities when using several reaction vessels are missing. However, this is necessary in order to produce aluminosilicates with a certain degree of crystallinity. * Compliance with a certain degree of crystallinity is necessary to control the kinetics of Ca ⁺ " ⁵ " and% ⁺ * exchange.

Object of the invention:

The aim of the invention is to eliminate the described deficiency of the known technical solutions au and to achieve a fast and continuous production of Alurao silicate with desired degree of crystallinity ¹ ^ ^he reproducible conditions and in short reaction times.

Invention:

The invention has for its object to provide a method that allows the production of aluminosilicates with the desired degree of crystal luster and in a technically easy to implement Rülirkesselkaskade.

According to the invention the object is achieved in that at 80 to 99 ⁰ G, preferably 90 to 95 ° C, aufgeheiste Natriumaluminat- and silicate silicate solutions in a known ratio of 1.6 to 2.2 mol SiO / AlgO ^, 1.8 to 4 moles of IJa ₂ O / Al ₂ O ₃ and 15 to 40 moles of H ₂ OATa ₂ O are simultaneously introduced continuously into a reaction vessel, wherein the products

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intensively stirred at the same or deviating temperature and after a mean residence time of 10 to 45 minutes are transferred to one or more downstream reaction vessels in which the reaction products at the same or + 10 ⁰ C deviating temperature 10 to 20 minutes with less movement The reaction radii of the agitators from the reaction vessel one to the subsequent reaction vessel (s) such as 10 to 25 to 1 and the volumes of the reaction vessel are from 0.5 to 4 to 1.

There are no special requirements for the sodium aluminate and sodium silicate solutions used. They should be free from insoluble substances and the content of heavy metal ions, such as iron, B, should be as low as possible to avoid contamination of the desired end product and erroneous crystallizations.

If the amounts of alkali available are too high in the aluminate and silicate solutions used , then the alkali to be added may be added to both the aluminate and silicate solutions, or any proportion of both solutions. The Ha ^ O / Al ^ Oo ratio must be matched with the desired residence time and the desired degree of crystallinity of the aluminosilicates to be prepared v / ground. Very short residence times, under 30 minutes, require a molar ratio of Ila ^ O / O ^ O, from 2.5 to 4, "S ¹ Ur residence times of 30 to 75 minutes is a molar ratio of 1.8 to 2.5 is sufficient ( Table 1).

For the Durchgangsung of the starting products and the reaction solution is to work in the cascade with different stirring intensities. Engraving intensity can be named after Serner (Chem. Engae. 52 (1950) 4, 123) with an "effective radius of the stirring effect or, as such," effective radius ".

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be written. It can be used for turbine and propeller stirrers after the rollover formula

H . , _a . o, 15. JLJ

⁰ "* £. 0.00211

where R = effective radius, a = friction loss, H = stirrer power, ** g = dynamic toughness of the reaction solution.

The ratio of the radii of action in 1 _e and 2 resp

 further reaction vessels is achieved, for example, by using a turbine stirrer in a 1 "reaction vessel and a propeller stirrer in the 2 × reaction vessel. However, other stirring systems, such as vibrating stirrers or mixing nozzles in the 1e reaction vessel and bar or paddle stirrer in the second reaction vessel, are also possible. If further reaction vessels are connected downstream, then it is possible to work with the same or lower stirring intensity as in the second reaction vessel

 The reaction volumes of the reaction vessels used are coordinated so that between the volume of the reaction vessel one to the subsequent reaction vessels or a ratio of 0.5 to 4 to 1.

The reaction or residence side can be further shortened by pumping back a portion of the reaction solution, including the solid substance contained therein, from the reaction chamber or a downstream reaction vessel into the first reaction vessel. The reaction solution thereby circulating should amount to 5 to 30% by volume of the total reaction solution.

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Table 11 Influence of residence time and molar ratio

pOo on the crystallinity of aluminosilicate

Residence time in ΪΓβ _? 0 / Α1 _? 0 ₃ in the crystallinity of the cascade 3 :) Initial solutions of the obtained

aluminosilicate

37.5 2.3 97

18.5 4.0 87

44.0 2.1 100

23 * 2 3.5 84

^J Cascade of two stirred vessels, ratio of the radii of action 15 si

For example, see Example 1

Aluminates and silicate solution with molar ratios of 2.3 ₂ AlpOo ί 1.7 SiOp: 75 HpO are continuously pressed by dosing pumps through a heat exchanger and heated here to 95 ⁰ C · They are then introduced into a reaction vessel with Surbinenrülirer, which is filled with water "Via an overflow, the reaction solution then enters a second reaction vessel with bar stirrer. The (temperature in the two reaction vessels is 93 ⁰ C, wherein the Wirkungsraaien the stirrer as 15: 1 and the reaction volumes of the two reaction vessels behave like 1i1 The average residence time of the reaction solution is a total of 30 min, 15 min each in the reaction vessels one and two After the stationary operating state has been reached, separation of the mother liquor from the formed crystalline aluminosilicate of type A takes place continuously, which has the following characteristics:

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Chemical composition in the decomposed state 0,96 ^ a ₂ O: Al ₃ O ₃ : 1 ,? SiOg

Crystallinity: 88 %, based on a standard type A zeolite; CaO uptake (rapid test, 15 min) 153 mg CaO / g active substance; H ₂ 0 ~ Adsorpti © ii (static conditions 80 Pa _Q ) 18,1

Example 2

According to Example 1, an aluminate and silicate solution having the molar ratios of 1.99 Na ₅₁ O: Al ₉ O-. : 1.7 SiO ₉ : 63.5 H ₉ O, which are heated to 99 ° C. Notwithstanding Example 1, the temperature of the reaction vessel is one 93 ⁰ C, the reaction vessel two 96 ⁰ C. ®a, s ratio of the radii of action of the stirrer is 10: 1, the reaction volumes of the reaction vessels are in the ratio 1.5 ί 1 _S the entire Lingering since is 26 min, 16 min in the vessel one and 10 min in the vessel two. The resulting crystalline aluminosilicate of type A has the following characteristics:

Chemical composition: 0.92 Sa ₂ O: Al ₂ O ₃ : 1.75 SiO ₂ ; Crystallinity: 82%; CaO uptake: 123 mg CaO / g; HgO ^ dsorption: 19.1 wt _e -% "

Example 3

According to Example 1, an alumnate and silicate solution with the molar ratios 2.05 Na ₂ O; Al ₂ O ₃ : 1.7 SiO ₂ : 75 H ₂ O, which are heated to 99 ° C. The temperature in the reaction vessel one amounts to 91 ° G, in the reaction vessel 94, two ⁰ C * The ratio of Y / irkungsradien the stirrer is 10: 1, the reaction volumes of the reaction vessels are in the ratio 0.5! 1 »the total convection time is 42 min, 14 min in vessel one and 28 min in vessel 2 * The obtained crystalline aluminosilicate of type A has the following characteristics: Chemical composition: 0.94 Ma ₂ O: Al ₃ O ₃ : 1 , 72 crystallinity: 94%; OaO uptake: 151 mg CaO / g; ion: 20.7% by weight.

"O

Claims (1)

-9- 22 3 33 6 invention claim Process for the preparation of semicrystalline and crystalline aluminosilicates of the type zeolite A from ITatriuraaluniinat- and Hatriumsilikatlösungen in a ratio of 1.6 to 2.2 mol SiO ₂ ZAIgO ₃ , 1.8 to 4 moles of Na ₂ OAl ₂ O ₃ and 15 to 40 Mol HgO / HagO, characterized in that the Hatriumaluminät- and IJatriumsilikatlösungen first to 80 to 99 ⁰ C, preferably 90 to 95 ⁰ C, heated and continuously be introduced simultaneously into a reaction vessel, wherein they at the same barder + 10 ⁰ C deviating temperature stirred intensively and after a mean residence time of 10 Ms 45 minutes in one or more downstream reaction vessels are transferred, in which the reaction products at the same or hk 10 ⁰ C deviating temperature for 10 to 20 minutes linger with less movement, v / if the Y From the reaction vessel one to the one or more subsequent reaction vessels such as 10 to 25 su 1, and the volumes of the Re action vessel one to your or the subsequent reaction vessels such as 0.5 to 4 to 1 behave »