Influence of synthesis parameters on the morphology and particle size distribution of zeolite L

Zeolite L was synthesized hydrothermally from the substrate mixture of Na2O-K2O-Al2O3-SiO2-H2O system at temperatures of 373similar to443 K, and the influence of various synthesis parameters on the particle size distribution and surface morphology was investigated. The crystalline zeolite L samples obtained were characterized by means of X-ray powder diffraction, scanning electron microscopy, and particle size analysis. It was established that as the synthesis temperature increased, the average crystal size becomes larger with a broader particle size distribution. Particle size distribution and morphology of zeolite L was also affected by the silica source and the molar ratios of SiO2/Al2O3, (K2O+Na2O)/SiO2, Na2O/(K2O+Na2O), and H2O/(K2O +Na2O). The crystal size decreased significantly by stirring the gel during the synthesis or subjecting the substrate mixture to an aging treatment at room temperature before hydrothermal treatment. Different heating rates applied prior to subsequent isothermal crystallization at 443 K also significantly influence the particle size distribution and the morphology of zeolite L.