Solid transformation of zeolite NaA to sodalite

Sodalite was successfully synthesized by solid-state transformation of NaA in the presence of excess NaCl. The transformation conditions, effect of cation exchange, and treatment agents were investigated. The transformation mechanism is proposed as zeolite A → carnegieite → sodalite. When the temperature is above a threshold value, the transformation is abruptly accelerated. K- and Cs-exchanged zeolite A are transformed more rapidly than NaA. Sodalite could not be formed when the NaA was treated with KCl.