Synthesis of molecular sieves from Chilean kaolinites: 1. Synthesis of NaAtype zeolites

The synthesis of NaA type zeolites has been studied at autogenous pressure using Chilean kaolins as starting materials. The ratios of SiO2/Al2O3, Na2O /SiO2, H2O/Na2O have been set at 1.9 or 2.5, 0.6 or 1.0 and 50 or 90, respe ctively. Reaction times have been 5 or 15 h and reaction temperature 80 or 100 degrees C. The influence of these parameters on the textural and struct ural properties of the zeolite has been studied. All samples have been char acterized by X-ray diffraction, infrared spectroscopy, scanning electron mi croscopy, differential thermal analysis and cation exchange capacity. The b est conditions for synthesis are: SiO2/Al2O3 = 2.5, Na2O/SiO2 = 1.0, H2O/Na 2O = 50 and 15 h reaction time at 100 degrees C. (C) 1999 Society of Chemic al Industry.