Toyo Soda Manufacturing Co., Ltd.

Shinichi Hashimoto

Hiroshi Miyazaki

Isao Miyanohara

A Y-type zeolite having a SiO.sub.2 /Al.sub.2 O.sub.3 ratio of at least about 4 is produced by the following process. In the first step of the process, an aqueous alkali silicate solution and an aqueous alkali aluminate solution are mixed together in the presence of an alkali in an amount such that the ratio of M.sub.2 O(M: an alkali metal)/Al.sub.2 O.sub.3, present in the mixed solution, is at least about 5 by mole, followed by forming a gel in the mixed solution and, then, separating the gel therefrom. In the second step, the separated gel is incorporated in an aqueous alkali silicate solution or an aqueous alkali silicate-alkali mixed solution to obtain a slurry and, then, a Y-type zeolite crystal is formed in the slurry.

Process for producing Y-type zeolite

Zeolite substantially free from a free alkali ingredient is produced by a process wherein a silica source and an alumina source is reacted in an aqueous reaction medium containing an excessive amount of an alkali ingredient to form zeolite, followed by separating the so formed zeolite from the aqueous alkaline reaction medium or from an aqueous medium in which the zeolite, after being separated from the aqueous alkaline reaction medium, has been slurried. The separation of the zeolite from the aqueous alkaline reaction medium or from the aqueous medium, in which the zeolite has been slurried after being separated from the aqueous alkaline reaction medium, is effected in the added presence of an alkali metal or alkaline earth metal salt of aluminic acid.

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Shin Nanyo, Japan

Shinichi Hashimoto