Effect of the atomic arrangement of amorphized zeolite on the recrystallization behavior to crystalline zeolite

Abstract

Different types of amorphous solids derived from Na- and K-zeolite A were prepared by mechanical or post-mechanical thermal treatments and changes in the atomic arrangement of these solids were characterized by high-energy X-ray diffraction (HEXRD). HEXRD measurements revealed that the structures of the amorphous solids after mechanical and post-mechanical thermal amorphization were different from one another. These amorphous solids were recrystallized to zeolite and the effect of the atomic arrangement of the raw materials on zeolite crystallization behavior was investigated. It was also shown that the recrystallization behavior of amorphous solids back to zeolite is different in mechanically and post-mechanical thermally amorphized samples. This arises from the difference in the medium range order in the amorphous solids; that is, post-mechanical thermally amorphized samples were more able to change into dense phases since the ring structure of zeolite A was more distorted and/or destroyed than in only mechanically amorphized samples.