Authors: J.-Ch. Buhl, S. Cramm
Affilation: Leibniz University Hannover, Germany
Pages: 284 - 287
Keywords: nano-zeolites, nitrate storage, hydrothermal synthesis, stacking disorder
Synthesis of nitrate enclathrated nanocrystalline aluminosilicate zeolite was performed in the system Na2O-SiO2-Al2O3-H20-NaNO3-(TEA) under superalkaline low temperature conditions at 333 K. Formation of nanoparticles occurred already after 3 hours with sizes not exceeding 50 nm and total batch compositions of Na7.5[AlSiO4]6(NO3)184.108.40.206H2O. XRD revealed the nanocrystallites as nitrate enclathrated intermediate phase (INT) between the structures of zeolites sodalite (SOD) and cancrinite (CAN). INT can be characterized by one dimensional stacking disorder of aluminosilicate layers along hexagonal c-axis. In CAN framework these layers show AB-stacking and SOD exhibits cubic ABC-sequence. It was further found that TEA acts as an effective agent to influence the morphology of nanoparticles in the NaNO3 bearing high alkaline aqueous reaction system. INT was found here as big spheres formed by countless nanocrystalline rods of about 40 nm diameter and about 250 nm in length. The low temperature and short synthesis times are revealing INT as an economic material for nitrate uptake and storage. Further properties like thermal behaviour will be presented and compared with microcrystalline nitrate CAN.