Faujasite zeolite preparation process

摘要

Disclosed is a process for the preparation of a faujasite zeolite. A starting zeolite of the faujasite structure having a silica to alumina ratio of from 4.5 to 6.5 and an alkali level of less than 1.5% wt is steam calcined to produce an intermediate zeolite. The intermediate zeolite is treated with an acidified solution having specificately defined characteristics.

主权项

1. A process for the preparation of a zeolite having a unit cell size in the range of from 24.42 to 24.52 Å; a bulk silica to alumina molar ratio (SAR) in the range of from 10 to 15; and a surface area of from 910 to 1020 m2/g, which process comprises:
a) providing a starting zeolite of the faujasite structure having a silica to alumina ratio of from 4.5 to 6.5 and an alkali level of less than 1.5% wt; b) steam calcination by treating said starting zeolite at a temperature in the range of from 550 to 750° C. and at a partial pressure of steam in the range of from 5 to 50 vol %, basis total gas present, for a time effective to produce an intermediate zeolite having a unit cell size of from 24.40 to 24.50 Å; c) contacting the intermediate zeolite with an acidified solution comprising of from 4 to 9 mmole of acid having a pKa below 0 per gram of zeolite and optionally an ammonium salt under conditions effective to produce a zeolite having a unit cell size in the range of from 24.42 Å to 24.52 Å; a SAR in the range of from 10 to 15; and a surface area of from 910 to 1020 m2/g; and d) recovering said zeolite.