Fast hydrothermal ammonium exchange of zeolite Na-Y

Abstract

Hydrothermal heating to 433 K is shown to reduce drastically the time needed for attaining 70–100% ammonium exchange of zeolite Na-Y without impairing the zeolite. Upon approaching complete ammonium exchange the affinity of zeolite Y for ammonium falls sharply. Complete exchange requires a total molar ammonium : sodium ratio of more than 200. Extensive ammonium exchange is accompanied by an expansion of the faujasite framework eventually leading to sodalite cages of sufficient size to accommodate two ammonium ions.