Theoretical study of hydration of zeolite NaA

Abstract

In this theoretical study of the hydration of zeolite NaA, the radius of the model compound is 11A, and it``s repeating unit is ($SiO_2AlO_2$). In the framework of A type zeolite, there are three kinds of oxygens. The obtained net charges of each oxygen atoms are $\delta_{0(1)}$=-0.395, $\delta_{0(2)}$=-0.440, and $\delta_{0(3)}$=-0.399 respectively. There are four kinds of hydrated waters in the α cage. The average binding energy of water(1), water(2), and water(3) are -29.847, -25.344, and -15.888 Kcal/mole respectively. The binding energy of water(4) is 52.147 Kcal/mole. Water(1) is bound to Na(1), water(2) is bound to Na(2), and water(3) form a hydrogen bonding with water(1). Water(4) is bound to Na(3) in dodecahedral cage. Water(1) and water(3) form a distorted dodecahedral cage. In the case of hydrated zeolite NaA, Na(3) is located in dodecahedral cage and is bound to water(4).