Abstract: The crystallinity of rare earth (RE) exchanged zeolite Y is determined by XRD method. Results show that with the increase of RE contents in zeolite, the zeolite crystallinities decrease significantly, and the changes of crystallinity are not reflecting vary from zeolite crystal structure, just because the determination of zeolite crystallinity by XRD is disturbed by the existence of rare earth cations. The distribution of RE in zeolite trends to be even during calcination, thus the effect of RE cations on the determination of crystallinity is less for calcined RE-exchanged zeolite Y. By mathematical fitting, a formula is established between the changes of zeolite crystallinity and the contents of rare earth oxide in zeolite.

Key words: XRD, zeolite, crystallinity, rare earth