US 4,303,629 AGranted

Crystalline zeolite powder of type A (I)

AssigneeDegussa & Henkel Kommanditgesellschaft auf Aktien

InventorsHans Strack, Wolfgang Roebke, Dieter Kneitel, Ehrfried Parr

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Abstract

There are produced crystalline zeolite powders of Type A with the composition 1.0.+-.0.2 M.sub.2/n O:Al.sub.2 O.sub.3 :1.85.+-.0.5 SiO.sub.2 .multidot.y H.sub.2 O where M is a metal cation, n is its valence and y has a value up to 6 with 50 weight % of the particles not over 4.0.mu. and with a particle spectrum ______________________________________ Fraction (.mu.) Portion (weight %) ______________________________________ <3 35 to 60 <5 82 to 95 <10 93 to 99 <15 96 to 100 ______________________________________ by hydrothermally crystallizing a SiO.sub.2, Al.sub.2 O.sub.3, Na.sub.2 O and water containing alkali aluminate, water, silicate synthesis mixture with optionally a tempering step wherein in a given case during the crystallization or tempering step instead of stirring shearing forces are employed. The process comprises providing an aqueous alkali silicate soluton, heating it to a temperature between 30.degree. and 80.degree. C., adding to the alkali silicate solution with stirring aqueous sodium aluminate having a content of 0.1 to 100 grams Al.sub.2 O.sub.3 /l and 1 to 200 grams Na.sub.2 O/l and which had been pre-warmed to from 30.degree. to 100.degree. C. until the turbidity point of the reaction mixture within 10 to 60 minutes, adding with stirring to the turbid reaction mixture which had the composition SiO.sub.2 /Al.sub.2 O.sub.3 =2 to 50:1, Na.sub.2 O/SiO.sub.2 =0.2 to 20:1 and H.sub.2 O/Na.sub.2 O=4 to 300:1 an aqueous sodium aluminate which contains 10 to 200 grams/l of Al.sub.2 O.sub.3 and 10 to 250 grams/l of Na.sub.2 O having a temperature of 10.degree. to 100.degree. C. and allowing the thus obtained synthesis mixture to crystallize at a temperature within between 20.degree. and 175.degree. C. in at least 15 minutes.

Claims10

Dependent claims

A process of preparing a crystalline zeolite powder of Type A with the composition

1.0.+-.0.2 M.sub.2/n O:Al.sub.2 O.sub.3 :1.85.+-.0.5 SiO.sub.2.yH.sub.2 O
where M is a sodium cation, n is its valence and y has a value up to 6 with 50 weight % of the particles not over 4.0.mu. and with a particle spectrum:
______________________________________ Fraction (.mu.) Portion (weight %) ______________________________________ <3 35 to 60 <5 82 to 95 <10 93 to 99 <15 96 to 100 ______________________________________
comprising hydrothermally crystallizing a SiO.sub.2, Al.sub.2 O.sub.3, M.sub.2 O and water containing alkali aluminate, water, alkali silicate synthesis mixture where M is sodium, said process including the steps of providing an aqueous sodium silicate solution containing 50 to 150 grams of Na.sub.2 O/l and 200 to 450 grams of SiO.sub.2 /l, heating it to a temperature between 30.degree. and 80.degree. C., adding to the sodium silicate solution with stirring aqueous sodium aluminate having a content of 0.1 to 100 grams Al.sub.2 O.sub.3 /l and 1 to 200 grams of Na.sub.2 O/l and having a temperature of from 30.degree. to 100.degree. C. until the turbidity point of the reaction mixture is reached within 10 to 60 minutes, adding with stirring in two steps to the turbid reaction mixture which had the composition SiO.sub.2 /Al.sub.2 O.sub.3 =2 to 50:1, M.sub.2 O/SiO.sub.2 =0.2 to 20:1 and H.sub.2 O/M.sub.2 O=4 to 300:1 an aqueous sodium aluminate which contains 10 to 200 grams/l of Al.sub.2 O.sub.3 and 10 to 250 grams/l of Na.sub.2 O having a temperature of 10.degree. to 100.degree. C., the speed of addition in the second step being 2 to 10 times higher than the in the first step and allowing the thus obtained synthesis mixture to crystallize at a temperature within between 20.degree. and 175.degree. C. for at least 15 minutes.

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Dependencies are inferred from the claim text.