DE2353921C2 - Crystalline berylloalumino-silicates and processes for their manufacture - Google Patents

Description

(Analclm. Natrolllh. ChabacH. PhIIIppsit. Heulandlt, Mordenil and Faujasil). As early as 1937 and especially from 1946 onwards, based on systematic investigations of the Na ₂ O / Al.Oi / SiO ₂ / H ₂ O system, synthetic zeolites were produced by hydrothermal means.

So is z. B. in the German Auslegeschrift 12 03 239 describes a process to synthetic molecular sieves, so-called Y zeolites. that are structurally related to the faujaslt. The general formula given for Na representatives of these cubic crystallizing Y zeolites is 0.9 ± 0.2 Na ₂ O: AljO,: WSlO ₂ : XH ₂ O, where W can assume values of more than 3 up to 6 and V can be a number up to means about 9.

Such Y zeolites and also X zeolites (this type of structure can form if the molar ratio of Al ₂ Oi to SlO ₂ in the above-mentioned gross formula is less than 3) have been used in many different ways in catalytic processes.

It is. as already mentioned, an important feature of Zeolilhlian alumino-silcats. that their properties can be changed by ion exchange. So it succeeds z. B .. to form the U-shape or NH ₄ -form of a zeolite from the Na form which is preferred in the manufacture of the zeolite. The replacement of the alkali metal by alkaline earth metals such as magnesium by heavy metals or by rare earth metals, e.g. B. Lanthanum or cerium is possible. A change in the properties of the zeolite through ion exchange alone, however, is often subject to narrow limits, because the zeolite framework and thus the properties of this framework cannot be significantly changed through ion exchange. So is z. B. for the cracking of hydrocarbons an internal search with acidic character is required. The acid centers are created by exchanging the cations for protons. The azidüä thus attainable! depends in particular on *. Dimensions depend on the structure of the zeolite. In most Zeollth species, it is essentially given by the composition and therefore practically cannot be changed significantly from the outset. Ways have therefore already been inscribed to modify the Zeollthgerüt. This can be achieved by replacing the elements silicon and aluminum, which are essential for the framework, with other elements. Thus, through a work by RM Barrer et al. J. Chem. Soc. London. 1959. Pages 195 to 208. known to partially or completely replace aluminum or silicon in aluminosilicates by gallium or germanium. They become Alumlno-Germanates. Gallosillcates or, if both framework formers are completely replaced, GaUo-Germanates are obtained, which structurally belong to the zeolites and enrich the Zeollth range with their special properties.

In the German Offenlegungsschrlflen 19 59 241. 20 34 266, 20 34 267 and 20 34 268 synthetic crystalline zeolites are described which contain phosphorus in addition to aluminum and silicon. Phosphorus replaces silicon in the so-called Alumlno-Silcophosphaien isomorphic, ie the three-dimensional network structure results from AlO ₄ -. SlO ₄ and vOt tetrahedra. which are each linked via oxygen atoms. As a result of the substitution of silicon by phosphorus in the crystal lattice (ie in the tetrahedra), a decrease in the smoothing constant can be determined crystallographically. In addition to the crystallographic findings, however, the IR spectroscopy also provided evidence that silicon had been replaced by phosphorus. The named substituted zeolites, like the base bodies, are capable of ion exchange and can be activated accordingly by heating. However, they show advantages over the basic bodies of the series in some respects. So z. B. the thermal resistance of Alumino-Slllcophosphaie be greater than that of Alumino-Sillkaten. The preparation of substituted aluminosilicates is generally more difficult than that of pure aluminosilicates, since uncontrolled side reactions often take place.

If one considers the previous attempts to substitute aluminum or silicon in alumino-silicates considered, it is noticeable that so far only elements of the 3rd, 4th and 5th main group of the periodic system were applied. When replacing aluminum with gallium or silicon with germanium nothing changes with respect to the electrovalence grid / cavity. When replacing silicon with phosphorus the negative charging of the network is reduced; there can therefore be fewer cations in the total Cavities of the dteldlmenslonal network are incorporated.

On the basis of previous knowledge of zeolites, it was not to be expected that if the trivalent aluminum or high-value silicon had been replaced by the bivalent beryllium, the further negative charging of the three-dimensional network associated with it would have been compensated for by the introduction of cations into the cavities can be. DE-PS 22 56 450 describes the production of zeolites of the Faujaslttype (Y zeolite), in the structure of which _{BeO 4} tetrahedra are also involved in addition to the _{SIO 4} and AlO _{4 tetrahedra customary for aluminosilicate.}

It is suggested that the Beryllo-Alumino-Slllkate from a mixture of sodium hydroxide. Sodium aluminate. Produce sodium lumberylate and SIO ₁ sol at room temperature by letting the mixture stand for 18 to 24 hours and then heating it to 50 to 105 ° C. until solid crystalline products are formed.

The patent mentioned shows that there is only about 50 ^l \. Have beryllium, based on aluminum, built into the aluminum osillkat. Berylloalumino-Slllkate can be obtained, which have a mol ratio SiO1 / AljO, from about up to 7.

The invention relates to crystalline berylloalumino-sulfates of the molar composition 1.4-2.6 Na ₂ O · Al ₂ O, 7-10 SlO ₂ · 0.5-1.5 BeO · 0-9 H ₂ O. which are an X-ray diffraction image with the following d -Values show:

23 53 921 d (k) intensity from ... to very strong hkl 14.20-14.00 middle 111 8.70-8.60 middle 220 7.42- 7.35 strong 311 5.65-5.59 middle 331 4.73-4.69 middle 331,511 4.35-4.30 strong 440 3.75-3.71 strong 533 3.29-3.25 middle 642 3.01-2.97 middle 733 2.90-2.86 strong 822, 660 2.84-2.80 middle 751.555 2.75-2.71 middle 840 2.62-2.58 middle 664 2.37-2.33 10,2,2; 666

The invention also relates to a process for the production of crystalline berylloalino-silicates of the type mentioned above by producing a mixture of sodium hydroxide, sodium aluminate, sodium lumberylate and SiO ₂ sol at room temperature, allowing the mixture to stand for 18 to 24 hours, then heating to temperatures in Range between 50 and 105 ° C until a solid, crystalline product has formed. Separating this product from the liquid, washing and drying, in which a mixture of the molar composition:

BeO / Al ₂ O, = 0.5 to 1.5

SlO ₂ / Al ₂ O ₃ = 12 to 30

Na ₂ O / SlO ₂ = 0.2-0.6

H ₂ 0 / Na ₂ 0 = 30 to 70

manufactures.

It has been found that aluminum can be substituted to a significantly greater extent by beryllium In these Alumlnoslllkaten, thereby resulting Beryllo-Alumlno-Sillkate having a molar ratio of SIO ₂ / Al ₂ O ₃ 7 to 10 It has been shown that beryllo-aluminum silcates of the faujasite type with more than 50% beryllium and up to 150 mol% beryllium, based on the aluminum, can be produced. These beryllo-alumino-silicates are generally produced by adding sodium lumberylate to a reaction mixture of aluminum and silicate components. It is essential for the production of the beryllium-rich zeolites of the faujasite type according to the invention that the SlO ₂ / Al ₂ O ₃ molar ratio in the reaction mixture is _{adapted to the respective BeO.'Al 2} O ₃ molar ratio in such a way that a large BeO / Al ₂ O ₃ molar ratio, a large SiO ₂ / Al ₂ O ₃ molar ratio is also selected (cf. example 3 b). If this rule is not observed, zeolites containing beryllium with a different structure are obtained (cf. example 3 a).

Berylllum-Zeollthe have a structure that is similar to the structure of the mineral Faujaslt. The d-values of the X-ray diffraction diagram can be assigned to a cubic unit cell. Lattice constants of 24.4 to 24.6 A occur. The dimensions of the unit cell are dependent on the beryllium content of the Depending on zeolites and can be in the above range, with higher beryllium contents being one lower lattice constant of the Berylllum-Zeollth. The table below contains the evaluation of an X-ray diagram of a typical Berylllum-Zeollth representative. In the table are essential and characteristic d-values of a Berylllum-Zeollth are given. It is important to note that the d-values likewise how the associated intensities depend on the beryllium and aluminum content of the zeolite and the Values of the representative of Berylllum-Zeollthe named in the table, therefore, in this form not for all Representatives apply. It is believed that beryllium substitution occurs by one of the following mechanisms expires:

1. 2 (AIO ₂ ) - = (BeSlO ₄ ) ² -

2. (AlO ₂ ) - = (BeO (OH)) -

However, other reaction mechanisms that can take place in the crystal at the same time are also conceivable.

It is known that the lattice constant of Faujaslt and of artificial zeolites of the Faujaslt type In

Dependence on the number of aluminum atoms in the unit cell Varies within relatively wide limits. the The dependence of the lattice constant on the composition of the unit cell can be given by the following equation be reproduced:

a "- ^192b

b and C are constants and stand for values of 0.00868 for b and 24.191 for C (compare Breck and Flanlgen. Molecular Sieves, edited by Soc. of Chemical Industry, London, 1968, Selten 54 ff).

From the known chemical analysis, with the help of this equation, the expected value of the i " Lattice constant a <, calculate. It has been shown that the lattice constant of all-encircling zeolites is always smaller Is than the expected value that can be obtained from equation 1 with the aid of the known Si / Al molar ratio can calculate, while with berylllumfrelen zeolites a good agreement of the experimentally found Lattice constants can be determined with the values calculated according to the above formula. This Finding is therefore also very plausible, since beryllium has about the same ion size as silicon.

There is still further evidence that the beryllium intervenes in the course of the reaction in the production of the beryllo-aluminum chloride and is incorporated into the zeolite. The molar ratio SlCVAI] O) is always smaller in herylum-containing zeolites than in the heryl-Hurnfrel zeolites, which have been produced with the same reaction methods. In the case of Berylllum-Zeollthen of the Faujaslt type, molar ratios SIO ₂ MI ₂ Oj of up to 10 can therefore be achieved. - '"

This is surprising. It is indeed stated in the patent literature for unsubstituted aluminum silicates, zeolites Y, that the molar ratio SIO ₂ ZAI ₁ Oj can be values from 3 to 6 (see German Auslegeschrift 12 03 239). In fact, however, only zeolites are described in the explanatory notes of this publication which have values for the molar ratio SIO ₂ / Al ₂ Oj of a maximum of 4.44. The difficulty of producing aluminum silicates with molar ratios SlO ₂ / Al ₂ Oj of greater than S is also evident from DE-OS 16 67 477, whereby special measures in the production of the zeolite molar ratios of a maximum of 5.8 are achieved. Compare Examples 5 and 6. Requests that support the above statements can be found on page 3, paragraphs 1 and 2, of the cited publication.

The Berylllum-Zeollthe are made from aqueous mixtures containing aluminum, silica, beryllium and contain exchangeable cations. The molar composition of the aforementioned mixture must be · '" There are very specific limits so that the desired beryllium-containing zeolites of the Y-type on hydrothermal Paths emerge.

The alkali metals, in particular sodium, are preferably used as exchangeable cations. An aqueous sodium berylate solution is particularly suitable as the beryllium source. To prepare the sodium berylate solution, in addition to the commercially available beryllium salts, such as. B. Be (NO ₁ )], κ minerals containing beryl, such as beryl, are digested. The alkaline digestion solution of beryl, a mineral which, in addition to beryllium, also contains aluminum and silica, can be used directly for the synthesis. The other participants in the reaction are: Silicic acid preparations such. B. silica gel. Silica sol. Silica and sodium silicate. Particularly reactive aluminum oxides such as γ- Al] O, or sodium aluminum oxide or aluminum hydroxides serve as the aluminum source. In order to set the necessary pH value, alkali hydroxides are preferably used, which provide the exchangeable cations.

The reactants are mixed in water in the cold and then hydrothermally treated until Crystallization occurs. To obtain solid, crystalline Berylllum Zeollthe which are crystallographically of the Faujaslt type (Y type), the mixture of the reaction participants must have the following composition (all information in molar ratios of the oxides):

BeO / Al ₂ O ₃ = 0.5 to 1.5

SiO ₂ / Al ₂ O, = 12 to 30

NajO / SIOj = 0.2 to 0.6

HjO / Na ₂ O = 30 to 70 *>

Reaction mixtures of the following have proven particularly preferred for the production of Berylllum-Zeollthen Composition, based on molar ratios of the oxides, proven:

BeO / Al ₂ O ₃ = 0.5 to 1.0

SlO ₂ / Al ₂ O ₃ = 12 to 15

Na ₂ O / SlO ₂ = 0.3-0.5

H ₂ 0 / Na ₂ 0 = 30 to 60

The reactants mentioned are first mixed at room temperature and about 18 to 24 STUN ^ω to the left at this temperature itself. The temperature is then slowly increased to 70 ° to 80 ° with stirring. The mixture is kept at this temperature until it takes on a slightly liquid consistency. The temperature is then increased somewhat, values between 95 and 105 ° C. are preferably maintained until crystallization occurs. This is generally the case after 2 to 150 hours, preferably after 10 to 40 hours. The crystals are separated from the aqueous phase by filtration and dried.

The Berylllum Zeollthe according to the invention are preferably used in the alkali or, in particular, in the Sodium form, manufactured; by treatment with aqueous solutions, they can be one-, two-, three- or vlerwer-

tiger Metalic are subjected to ion exchange. Particularly preferred are the alkali, in particular Sodium ions exchanged for ammonium or hydrogen ions, the so-called ammonium or H-forms of the Bcrylllum-Zcollthc are formed. These can then be calcined in in particular reactive sorbent masses or catalysts are transferred.

The Berylllum-Zeollthe are particularly suitable for replacing the pure Alumlno-Slllkatc in the known ones technical processes in absorption or in catalysis. They are characterized by a comparable WT '.- ί higher temperature resistance. This is particularly important in the regeneration of In catalysis Berylllum-Zcollthen played an important role.

The following starting materials were used for the experiments described in the examples below used in:

1. SlO ₂ -SoI with 29; 28.3 and 26.5 wt. SlO ₂

2. Technical sodium aluminumate

33% by weight Na ₂ O. 48.9% by weight Al ₂ O ₁ . 18 wt .- '\. HjO

^l% 3. Technical sodium hydroxide with 77.5% by weight. Na ₂ O and 22.5 wt% HjO
4. Sodium Cryllate Solution

became from Beryllluninilral. by falling Bcrylllumhydroxld with the calculated amount of sodium hydroxide and dissolving ilp «vpw: i« -hpnon Berylllunihydmxlds In sodium hydroxide, prepared.

example 1 27 g of sodium hydroxide and 27.5 g of sodium hydroxide (2.) were dissolved in 160 g of water and the solution was clear Solution 60 ml of sodium lumberylate solution added, the 0.162 mol of BeO, 0.2924 mol of Na ₂ O and 5.5 mol of water

' ^s Contained in 100 ml of solution. This was added to 400 g of SIOJ-SoI (I) (28.3 '\.

SlOj) given and stirred well for 3 to 5 minutes. The resulting reaction mixture had the following Composition, expressed in molar proportions of the oxides:

BeO / AljO, = 0.666

· '· "HjO / Na ₂ O = 43.6

SlO ₁ ZAl ₁ O, = 14.3

Na ₂ O / SIOj = 0.35

The mixture was allowed to stand for 16 hours at room temperature, then with stirring to 80 ⁰ C ^and heated and digested for 5 hours at this temperature until the mixture has a light liquid consistency had assumed. The temperature was then increased to 95 ° C. and the mixture was kept at this temperature for a further 80 hours until a crystalline product was formed. The crystalline product was nitrated, washed and dried. According to the X-ray findings, it consisted of crystalline Berylllum-Zeollth with the lattice constant B ₀ = 24.500 Å (cubic Y-type). The SlO ₂ / Al ₂ O, molar ratio results in about 8.0

Example 2

13 g of sodium hydroxide and 12 g of sodium aluminate (2.) were dissolved in 80 g of water. 40 ml of sodium lumberylate solution containing 3 mol of BeO and 6 mol of Na ₂ O in 1900 ml of solution, corresponding to 2415 g, were added to this solution. This was added to 200 g of sol (t.) (29% SlO ₂ ) at room temperature with stirring and stirred well for 3 to 5 minutes. The resulting reaction mixture had the following composition, expressed in molar ratios of the oxides:

N> BeO / AI ₁ O, = 1.09

H, O / Na ₂ O = 42

SlO ₂ / Al ₂ O ₁ = 16, S.

Na ₂ O / SlO ₂ = 0.365

>> The mixture for 16 hours at room temperature, was allowed to stand, then heated with stirring to 50 ⁰ C and digested for 17 hours at this temperature. The temperature was then increased to 100 ^° C. and the mixture was kept at this temperature for a further 80 hours. The crystalline product formed after this period was filtered, washed and dried. According to X-ray analysis, it consisted of crystalline Berylllum-Zeollth (cubic, Y-type). The analysis showed an SKVA1 ₂ O, molar ratio of 9.2.

Example 3

a) 21.9 g of sodium aluminate (2.) and 9.55 g of sodium hydroxide were dissolved in 80 g of water and 38.7 ml of sodium lumberylate solution were added to this solution, the 3 mol of BeO and 6 mol of Na ₁ O in 1300 ml

(·> Solution, corresponding to 1760 g, contained. This was at room temperature with stirring to 250 g of silicon

dloxldsol (1st) (26.5%) and the mixture stirred well.

b) In a parallel experiment, the same amounts of water were used. Alumina! and berylate produced a reaction mixture with a higher SiOj / AljOt-MoI ratio.

The reaction mixtures obtained from batches a) and b) had the following composition, expressed In molecular compounds of oxides:

; i) 0.845 b) 0.845 BeP'AI.O., 41.5 BeOM Ι.Ό., 43.6 H.O / NajO 10.5 HjO / NujO 16.5 SiOj / AliO.1 0.375 SiOj / AljO., 0.357 Na.O / SiO. Na> O / SiOi

The mixtures were allowed to stand at room temperature for 24 hours, then heated to 95 ° C. with stirring and left at this temperature until crystallization occurred. According to the X-ray diagram the reaction mixture a did not turn into a beryllo-aluminum silicate from the faujaslllyp (Y), but a beryllumhaltlger Zeollth A received. Reaction gcmlsch b), on the other hand, became a Bcrylllum-Zeollth with a faujaslt structure obtained, which had a SJO./A1>O.- ratio of approx. 8.5 um) whose RyvmgcmJ!; u> ™ .rnrn «! eh. with the Lattice constant a ,, = 24.50 cubic indicative.

Tabel

hkl

i- + k- + Γ

rcl. intensity

111 3 14.14 very strong 220 8th 8.66 middle 311 11th 7.39 middle 331 19th 5.62 strong 333,511 27 4.71 middle 440 32 4.32 middle 531 35 4.14 very weak 620 40 3.8? weak 533 43 3.73 strong 711,551 51 3.43 weak 642 56 3.27 strong 733 67 2.99 middle 822, 660 72 2.88 middle 751.555 75 2.83 strong 840 80 2.73 middle 911.753 83 2.69 very weak 664 88 2.61 middle 844 96 2.50 very weak 10.2.0; 862 104 2.40 very weak 10,2,2; 666 108 2.35 middle

Claims (2)

Patent claims: Λ. Crystalline Bcryllo-Alumlno-Slllkaie, characterized in that they have the molar composition 1.4-2.6 Na.O-ΑΙ.Ο, -7-lO SlO. 0.5-1.5 BeO 0-9 11.0 and show an X-ray diffraction image with the following d-values: ί / (λ)
hkl from his intensity very strong middle middle strong middle middle strong strong middle middle strong middle middle middle 2. A process for the production of crystalline beryllo-alunilno-Slllkate according to claim 1 by producing a mixture of sodium hydroxide. Sodium aluminate. Sodium berylate and SiO ₂ -SoI at room temperature, let the mixture stand for 18 to 24 hours, then heating to temperatures in the range between 50 and 105 "C until a solid, crystalline product has formed. Separate this product from the liquid, washing and Drying, characterized in that a mixture of the molar composition is used: BeO / AI ₂ O, = 0.5 to 1.5 SlOj / AljO, = 12 to 30 Na ₂ O / SlO ₂ = 0.2 to 0.6 H ₂ 0 / Na ₂ 0 = 30 to 70 manufactures. Ill 14.20-14.00 220 8.70-8.60 311 7.42- 7.35 331 5.65-5.59 331,511 4.73-4.69 440 4.35-4.30 533 3.75-3.71 642 3.29-3.25 733 3.01-297 822,660 2.90-2.86 751.555 2.84-280 840 2.75-2.71 664 2.62-2.58 10.2.2; 666 2.37-2.33 The present invention relates to synthetic, crystalline berylloalumino-Slllkate, which to the structure type Faujasite (Y-Zeollthe) are to be expected as well as a method for their production. Among the aluminum silicates, zeolites are of great economic importance today. In the past decade, zeolites have gained technical importance as ion exchangers, molecular sieves and catalysts. They are used, among other things, as selective absorbents for hydrocarbons and water or as catalysts for the catalytic and hydrogenative splitting of hydrocarbons or as carrier material for active metals. The properties of the zeolites, especially their ability to act as an ion exchanger or as a body with molecular sieve properties and as catalysts, are structure-dependent. The zeolites are made up of SIO ₄ and AlO <tetrahedra linked three-dimensionally via oxygen atoms. This results in a three-dimensional network with cavities of a certain size. These cavities contain both water molecules and cations that saturate the electrovalence of the AIO ₄ tetrahedra. The cations located in the cavities, e.g. B. Alkall or Erdalkallkatlonen, are exchangeable and can be exchanged for other cations using well known ion exchange techniques. Zeolites can be activated. By heating them to a temperature at which the In den Water of crystallization bound to the cavities is released. After this activation, zeolites are able to form gases and selectively adsorb liquids. Alumlno-Slllkaie with Zeollth structure are widespread in nature. Due to structural differences Zeolites are divided into several classes, which were named after naturally occurring representatives