Phase-Controlled Synthesis of Zeolites from Sodium Aluminosilicate under OSDA/Solvent-Free Conditions

OSDA/solvent-free synthesis of zeolites is suitable for practical commercialization due to low environmental damage and low cost. However, only a few types of zeolites have been successfully synthesized by this method. In this study, ANA, CAN, GIS, SOD, FAU and LTA type zeolites were synthesized by the OSDA/solvent-free synthesis method by changing the Si/Al ratio and crystallization temperature in detail. At higher Si/Al ratios, FAU, GIS and ANA type zeolites were obtained with an increase of crystallization temperature. Meanwhile, at lower Si/Al ratios, LTA, SOD and CAN type zeolites were obtained with an increase of crystallization temperature. It was found that zeolites with high T atom density were synthesized with an increase of the crystallization temperature; zeolite with a high T atomic density is more stable. This work reveals the correlation between the Si / Al ratio and the crystallization temperature in OSDA/solvent-free synthesis of zeolites, which provides a clear guideline for the OSDA/solvent-free synthesis of zeolites.