Phase equilibria in the H 3Oβ″Al 2O 3H 2O 2H 2O system and the thermodynamic stability of H 3Oβ″Al 2O 3

Abstract

The thermodynamic stability of H 3Oβ″Al 2O 3 is considered via phase equilibria calculations in the H 3Oβ″Al 2O 3H 2, −O 2 and −H 2O systems. The results show that the vaporization of H 2O leads to the decomposition of H 3Oβ″Al 2O 3, that appreciable dehydration takes place >; 400 K and that an equilibrium composition of (H 3O) 2O:8–9Al 2O 3 is maintained 500–700 K under 0.3–1 atm steam pressure. It was also determined that oxygen and hydrogen pressure have insignificant influence on dehydration. Equilibrium relationships between the nonstoichiometric compositions of H 3Oβ″Al 2O 3, and the partial pressure of H 2O and temperature are developed.