Crystalline zeolite powder of type A (V)

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 6.2.mu. and with a particle spectrum: ______________________________________ Fraction (.mu.) Portion (weight %) ______________________________________ <3 10 to 60 <5 25 to 95 <10 80 to 99 <15 92 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 an optional 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 aluminate liquor having a temperature of 50.degree. to 90.degree. C. and containing 0.1 to 100 grams of Al.sub.2 O.sub.3 /l and 1 to 200 grams of Na.sub.2 O/l, feeding in with stirring an alkali silicate solution, to the turbid reaction mixture having 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/NaO=4 to 300:1, adding with stirring in two steps an aqueous sodium aluminate which contains 10 to 200 grams/l ot Al.sub.2 O.sub.3 and 10 to 250 grams/l of Na.sub.2 O and 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. inside at least 15 minutes.

Dependencies are inferred from the claim text.