Thermal expansion and contraction behavior of zeolites is critical for understanding long term mechanical stability of zeolite. For NaX and NaY, in the low temperature range, they show thermal contraction and then with increasing temperature their volumes normally increase. Recently, Krokidas et. al. reported lattice dynamics simulation of thermal behavior of faujasites (J. Phys. Chem. C 2010, 114, 22441). To simulate the temperature effect, they devised an equation of motion where the driving force is calculated by the first derivative of the Helmholtz free energy. In this work, we carry out molecular dynamics (MD) simulations to explicitly deal with the temperature effects. We adapted the potential forms and parameters used in the lattice dynamics simulations but some parameters need to be optimized for MD simulations. We analyzed the MD trajectories to rationalize the volume change in terms of bond lengths and angles.

Temperature dependence of volume change of NaX and NaY zeolites using molecular dynamics simulations

246th National Meeting (2013)

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