DE2725496A1 - METHOD OF PREPARING ZEOLITE A - Google Patents

Description

DR. BERG DIFL I. ^W G. STAPF

DIPL.-ING. SCH ^ ABK Dk UR. SANDMAIR 2 7 2 5 A 9 6 PATENT LAWYERS

P.O. Box 860245, 8000 Munich 86 Attorney's file 28 051 JUNE 6! 1977

Be / ßch

Ethyl Corporation Richmond, Virginia / USA

"Process for the production of zeolite A"

This invention relates to an improved method of manufacture des Zeolite A. In particular, this improved process gives this product, in which one in a single stage metakaolin and sodium hydroxide (NaOH) in aqueous solution. According to the invention, shorter process times are possible in addition to the advantage of a one-step process.

Case 4231

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t (OK) 911272 MauefkiRhenu 45 MOO Some W banks:

* ^C73 telegrams: Bayerische Veransbank Manchen 453100

OC74 BERGSTAPFPATENT Manchen Hypo-Bank Manchen 3190002624

«■ 3310 TELEX 0524 5MBERGd Pouscheck Manchen 65343-HS

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The properties , . Formulas and the preparation of zeolite A are well known and are described, for example, in U.S. patents 3,114,603 and 3,119,659, all of which are incorporated herein by reference.

According to the process of US Pat. No. 3,114,603, synthetic zeolite A is produced in a two-stage process, in which the reactants are combined and digested at a temperature of 20 to 55 ° C. for at least 2 hours in a first stage and then in a second stage heated for a longer period of time at least 75 ° C. In general, the preferred total time for the two steps in the examples of US Pat. No. 3,114,603 is from 7.5 to 48 hours.

According to the present invention, superior results are achieved when metakaolin and sodium hydroxide (NaOH) are reacted in aqueous solution at a temperature of about 80 to 85 ° C. for about 1 hour or longer to about 15 hours, although the short reaction times of 1 to 3 Hours are high performing . Metakaolin, water and NaOH are used in proportions which correspond to the desired Na, Al, Si and acid-off ratios of the Zeolite A, the molar ratio H ₂ 0 / Na ₂ 0 in the system from about 15 to about 200, preferably before is about 25 to 50 and especially 40.

The zeolite A has the formula

1.0 + 0.2 Na ₂ OiAl ₂ O ₅ : 2.0 + 0.5 SiO ₂ : YH ₂ O,

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& ■■ && ■ '■'

wherein Y can have a value up to about 5 »1.

A preferred zeolite is shown in Belgian patent 814 8-4 with the formula

wherein χ is a number from 20 to 30, preferably about 27. According to the method of the present invention is the manufacture such zeolites are desirable.

Prior art such as the U.S. patent 3 114 603 it is known that the aforementioned zeolites can be produced on the one hand by one reacts metakaolin and NaOH in aqueous solution; however use it such prior art processes involve a two-step process in order to obtain a product of high purity (about 80 # zeolite A B unit) in which the reactants put together and at room temperature (20 to 25 ° C) for several hours, after which the temperature is set to a Temperature in the range of 75 to 110 ° C for a longer crystallization process elevated. Obviously afterwards it is known that the two-step process is required to avoid the presence of by-products or impurities such as others Zeolite, hydroxysodalite or amorphous substances in the desired product to avoid »the decrease.

In contrast, it has now been found that a one-step process is possible if a reaction time of 2 to hours is used and that with such a shortened time

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for a one-step process, the zeolite A with a purity of 90 # or higher can be easily obtained. It's on it to point out that the present plague makes it possible the design of the equipment used to manufacture Zeolite A. to simplify, such simplification translating into cost reductions. It has been found that, for example a reaction time of 2 hours at 85 ° C is sufficient for substantially complete reactions to final product purity of 95 # or higher.

The product thus obtained is easily filtered or centrifuged won, after which the product obtained to remove residues of mother liquor and impurities washes. The washed product is then dried to remove residual water.

Although the mother liquor removed from the product and the washing water are completely or partially in the reaction stage however, can generally be used with the addition of fresh feed reactants less preferred than performing one or more additional crystallizations to remove what is still contained therein Winning product. In such a preferred process sequence, a water solution is obtained according to the present process of NaOH, which one would rather react with metakaolin than circulating an aqueous NaOH solution Mother liquor, _ for implementation. With Me ^ akaolln. Mlde ± _ »

Of course, it is clear that the present method uses the circle ' ⁰

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running of the mother liquor and the washing liquors from the reaction system does not exclude and that such a cycle can be advantageous under suitable conditions. It should also be pointed out that the overall recycling of the mother liquor is usually not desirable in such systems; because purification of some of the circulated stream is usually desirable or necessary to avoid the build-up of contaminants.

The present invention uses the meta-Porm amorphous kaolin, the so-called metakaolin or the equivalent product, which is preferably obtained by calcining kaolin at a temperature of about 550 to about 900 ⁰ C. Such firing is known to those skilled in the art and no further details need to be explained here because it is described, for example, in US Pat. No. 3,114,603, which is incorporated herein by reference. As discussed in US Pat. No. 3,114,603, it is usually desirable to avoid a prolonged lapse of time between the firing of the charge kaolin and its use in the present process.

The following examples show preferred embodiments and objects of the present invention.

example 1

250 g of H ₂ O are poured into a 1 liter round-bottomed flask equipped with a heating jacket and stirrer at room temperature. Then 34.5 g of NaOH beads are added and the mixture is stirred,

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until the HaOH is dissolved . 4Ό g of metakaolin are added and the mixture is heated to 85 ° C. The flask and contents are kept for 2 hours at 85 ° C. with stirring.

Remove the heating arm jacket and filter the contents of the flask with a Buchner funnel to collect the solid product . The product is washed with 300 g of water and dried in an oven at 100 ° C. for 5 hours or more.

If a sample of the product is analyzed by means of X-ray diffraction, it can be determined that a zeolite A of 95 or higher purity is obtained (ASTM X-ray powder diffraction pattern "Pile Card No. 11-590").

In this example the following molar ratios are used:

«2

3 " ² H ₂ OZAl ₂ O, - 78

- 39

Example 2

Example 1 is repeated using 125 g of water instead of 250 g and a temperature of 80.degree. C. instead of 85.degree. Similar results are obtained. The H ₂ 0 / Na ₂ 0 ratio is 20.

example 3

It is 579 1 deionized water in a reactor

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94-6 1 capacity, which is equipped with a steam jacket and agitator. 83 kg of sodium hydroxide beads are then added to the reactor. The mixture was heated at 81.6 ⁰ C (179 ⁰ S ¹⁾ and stirred for so long, until the beads are dissolved. Then 92.5 kg metakaolin is added to the reactor and raising the temperature to 85 ⁰ C (185 ° F). This temperature is maintained for 2 1/2 hours while the mixture is stirred. The reaction mixture is cooled to about room temperature and removed in four batches in a centrifuge in order to remove the supernatant mother liquor. The centrifuge cake is washed with 992 liters of deionized water. 1 kg of zeolite A are obtained. The product is essentially 100% zeolite A, determined by means of X-ray diffraction.

Example 4

Example 1 is repeated in various experiments under changing conditions. The results are in the table together with the results of Examples 1 and 2, here as Experiments I and II, respectively.

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Tabel

¹ T)
eat Ver
search H ₂ O
(κ) NaOH meta-
kaolin
(K) Temp.
( ⁰ C) Time Zeolite Product (JlS) Phillip
sit Ct
(D I. 250 34.5 40 85 2 hours. 95 A zeolite C - Ct
0> II 125 34.5 40 80 "2 hours 95 - - 3
CO IV 250 34.5 40 90 2 hours 63 - - 4th V 250 34.5 40 85 2.5 hours 96 - - O VI 250 34.5 40 85 3.5 hours 103 0 - VII 250 34.5 40 90 2 hours 78 0 some VIII 250 34.5 40 90 3 hours 76 0 some IX 250 34.5 40 90 4 hours 71 0 0 (O X 250 34.5 40 85-86 1 hour 0 α>
■ r » XI 250 34.5 40 85-86 2 hours 96 amorphous material - to
^, XII 250 34.5 40 85-86 3 hours 94 0 - XIII 250 34.5 40 85-86 4 hours 93 0 - approx XIV 250 34.5 40 85 2.5 hours 113 0 - -4 XV 160 34.5 40 90 65 min. 54 0 - XVI 160 34.5 40 90 2 hours 52 11 - XVII 160 34.5 40 90 2.5 hours 50 13th - XVIII 160 34.5 40 85 63 min. 60 12th - XIX 160 34.5 40 85 123 min. 62 11 - XX 160 34.5 40 85 183 min. 60 11 - XXI 160 34.5 40 80 2 hours 104 14th - XXII 160 34.5 40 80 185 min. 104 0 - Q

Claims (2)

Claims J ΠΑ Process for the preparation of sodium zeolite A by reacting liletakaolin and HaOH in aqueous solution, characterized in that the reaction is carried out in a one-step process at a temperature of about 80 to 85 ° C and about 1 hour or longer, whereby the solid sodium zeolite is carried out A receives. 2. The method according to claim 1, characterized in that g e k e η η draws that metakaolin, V / ater and UaOH in a ratio is employed to provide the desired IJa, Al and Si ratios of a desired zeolite A, and that the molar ratio HpO / NapO of the system is in the range of about 15 to about 100. 7fl9RA9 / 1 1 97