DD229391A1 - METHOD FOR PRODUCING MIXTURES OF MOLECULARS - Google Patents

Abstract

The process according to the invention for the production of molecular sieves relates to an ion exchange process. The aim of the invention is the minimization or complete elimination of the usual in ion exchange process disadvantages, z. B. unfavorable Materialoekonomie, high content of water pollutants, formation of heavy rainfall in the sewer network of a company or similar facilities. According to the invention, the object is achieved by treating the ion exchange solution to be discarded with untreated molecular sieve and the molecular sieve which has already been exchanged once or several times in the last exchange step with fresh ion exchange solution.

Description

VEB CHEMICALS BITTERFELD _Γ , 2498

Process for preparing mixed molecular sieves

Field of application of the invention

The invention relates to a process for the preparation of mixed zeolitic molecular sieves, which are then used alone or in corresponding mixtures in separation, adsorption, catalysis and the like.

Characteristic of the known technical solutions

As the prior art it is known that zeolites can be markedly changed in their property image by a partial or complete ion exchange with one or more cations other than originally contained in the zeolite.

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The ion exchange is usually carried out by treating the zeolite with the aqueous solution (s) containing the desired cation (s) while maintaining certain conditions (temperature, time, pH). The thus treated zeolites are separated from the ion exchange solution, washed and are then available for further processing or direct use. (DD-PS 109 985 and 112 659, DE-AS 1 467 053, 2 063 and 2 233 239, DE-OS 2 239 423)

The disadvantage of this procedure is the law that, in particular to achieve a high degree of exchange and in cations that have no significantly higher selectivity than to be exchanged from the zeolite, a very high excess must be presented, since only a small part of the cations offered is exchanged, it is also disadvantageous that to achieve a very high or complete ion exchange, this procedure must be performed twice or more often and the resulting replacement solutions are discarded, creating an unfavorable material economy arises. The exchange solutions to be discarded may cause further subsequent difficulties if the cations to be exchanged with other water (wastewater) ingredients, e.g. form sparingly soluble precipitates or are water pollutants, which must not be supplied to a receiving water.

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Object of the invention

It is the object and therefore the object of the invention to develop an ion exchange process that does not overcome the known disadvantages of conventional ion exchange processes - i.b. poor material economy, failure of poorly soluble precipitates in downstream facilities, discharge of water pollutants - has.

Explanation of the essence of the invention

According to the invention, the goal is achieved, shown in the example of ion exchange (IA) in 2 discrete steps, when the molecular sieve is treated in the first ion exchange first with an ion exchange solution, which has already been exchanged, separated from this solution and then in a 2 Ion Exchange with New Ion Exchange Solution Another cation exchange is performed. The process of the invention are accessible to all zeolitic molecular sieves, z. As type A, Σ, Y, mordenite, ZSM, alone or in mixtures, provided they contain exchangeable cations, which are resistant to other cations of the periodic table of elements, for. B. the groups Ia, Ha, Va, Via, Vila, VIII, Ib, Hb, be replaced.

Two tables should clarify the principle.

2498

Table 1

Exchange in 2 steps

Cycle name Ion exchange Hr. Molsieb loading with

Designation of the IA solution according to IA

1 MS 11 new solution L 11 MS 12 new solution. L 11 (2) 2 IIS 21 L 11 (2) L 12 MS 22 new solution L 21 3 MS 31 L 21 L 22 MS 32 new solution L 31 4 MS 41 L 31 L 32 , MS 42 new solution L 41

Table 2

Exchange in 3 steps

Cycle- designation ion exchange description of 3 Mr. molecular sieve Loading with ΙΑ solution according to IA 2 1 MS 11 new solution A 21 MS 12 new solution B 3 MS 13 new solution C 22 2 MS 21 B B 31 MS 22 σ -C 23 MS 23 , new solution L 32 3 MS 31 C 2 C 41 MS 32 L 21 L MS33 new solution L 4 MS 41 L 22 L MS 42 L 31 L MS 43 new solution L

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Cycle name Ion exchange Name of the Ur. Molecular sieve loading with IA solution according to IA

5 MS 51 L 32 L 33

MS 52 L 41 L 42

MS 53 new solution L 51

From the cycle, the molecular sieve samples -2, s. Table 1, -3, s. Table 2 and the solution samples -2 (-3) discharged, the waste product exchange solution (ideally) contains no more exchangeable cations in the molecular sieve. From Table 1 or 2 it can be seen that due to the two- (three) treatment of a molecular sieve first in the sum of a higher cation supply for the molecular sieve, than after two (three) times using the exchange solution. With the 4-cycle with twice or with the 5th cycle with three times the use of the exchange solution for ion exchange, however, constant technological conditions are assumed, s. Example Ba and Ca - a balance between the amount of cation exchanged into the molecular sieve and the cation amount of the "new solution". In general, the equilibrium position sets after a certain number of cycles depending on the exchange conditions and the type of cation to be exchanged. This equilibrium position is equally influenced by the factors known for ion exchange processes (for example selectivity, exchange time, temperature, concentration, stirring geometry) and must be taken into account. When this equilibrium is reached, the procedure according to the invention begins to become fully effective.

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At a maximum degree of exchange in the molecular sieve, a minimum content in the ion exchange solution to be discarded is achieved. This procedure has a particularly advantageous effect on the target position of high degree of exchange in the molecular sieve and low selectivity of the cation to be exchanged. By reusing the replacements already subjected to one (or more) replacements, the content of the cation (s) to be exchanged in the exchange solution to be discarded is minimized against Bull, thus producing a positive effect on the material economy. This minimization option also allows the formation of poorly soluble precipitates in downstream channels, among others. prevented and the separate treatment because of the presence of cations, which are water pollutants are superfluous.

embodiments

The invention will be explained in more detail below with reference to two exemplary embodiments, without restricting it to them.

Example 1 Exchange on molecular sieve type 132

Selected conditions for the exchange of Ba ions in molecular sieve type 13Σ:

two exchanges

Molecular sieve usage (anhydrous): Experiment 1-3 100 g

Trial 4 15 »8 g Replacement solution: 1 1 Exchanging temperature: 80 ⁰ C Replacement time: 2x6 hrs

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Table 3 Specification of the result of the 4-cycle (principle see Table 1)

Ver offer Ba -Kon Ba-out Ba residual search Mol Ba ⁺⁺ : concentration exchange degree salary in Mole 132 (*) (IA-SS) IA solution (Rel%) 1 1.05: 1 4.58 88.6 5.5 cm 0,95: 1 4.15 85.8 3.0 3 0.85: 1 3.71 79.6 0.6 4 1.05: 1 0.72 95.6 4.0

Example 2 Exchange on molecular sieve type 4A

Selected conditions for the exchange of Ca ions in the molecular sieve type 4A: two exchanges

Molecular sieve usage (anhydrous): 200 g

Exchange solution: 1 1

Exchange temperature: 25 ⁰ C

Exchange time: 2 2 3 hrs.

Table 4 Specification of the result after the 5-cycle (principle see Table 1)

Experiment 1 2

Offer Mol Ca ⁺⁺ : Mol 4A 0.768: 1 0.99: '

Ca ⁺⁺ concentration (g / l) 22.2 28.6

Ca ⁺⁺ exchange rate (IA-%) 65.0 69.1

Ca residual content in IA solution (xel%) 14.8 26.0

Claims (6)

- 8 - 2498 Inventions claim 1 I I t in that the ions are Ca or Ba cations 1 · Process for the preparation of mixed zeolitic molecular sieves by ion exchange, characterized in that the Ausgangsmolekularsieb is gradually subjected to an ion exchange, first in the first step (s) already used exchange solution and only in the last step, new exchange solution is used. 2. The method according to item 1, characterized in that the exchange takes place in 3 discrete steps. 3 «method according to item 1, characterized in that the exchange is made in 2 discrete steps. 4. Method according to points 1 to 3 »characterized in that ions of the elements of the groups Ia, Ha, and / or IHb of the Periodic Table of the Elements are used as ions. 5. Method according to items 1 to 4 »characterized in that as]
be used 6. The method according to points 1 to 5, characterized in that the exchange takes place in the temperature range 10 to 95 ⁰ G.