Synthesis of Pure Zeolite X from Palygorskite Clay Using a Two-Stage Method

A natural mineral, palygorskite clay, was used to synthesize pure zeolite X via a two-stage method. The synthetic parameters, such as calcination, crystallization time, and SiO2/Al2O3 molar ratio, were investigated. The results indicated that calcination enhanced the extraction of silica from palygorskite clay and was beneficial for the formation of zeolite X. Micro-sized pure zeolite X with the particle size of 1-4 μm was obtained in the gel with the SiO2/Al2O3 molar ratio range of 1.93 to 3 after hydrothermal treatment at 80 °C for 5 h. The synthetic zeolite X showed high specific surface area (487 m2/g) and low Si/Al ratio (1.17).