Thermodynamic and structural properties of tet-ZSM-5 and cal-ZSM-5 with different Si:Al ratios

Abstract

The thermodynamic and structural properties of different Si:Al ratios (Si96-yO192. AlyHy; 0≤ y ≤16) within crystalline siliceous zeolites: tet-ZSM-5 and cal-ZSM-5 have been calculated by using the lattice statics approach. Configurational averaging technique is adopted to obtain the thermodynamic and structural properties of ZSM-5 containing various ratios of Al content. The energy minimizations have been performed by GULP code with the shell model. The results show that pure siliceous ZSM-5 yields lowest lattice enthalpy compared to the other (Al,H)-ZSM-5 zeolites, Si96-yO192. AlyHy (1≤ y ≤16). Within the investigated systems with different Al contents, the orthorhombic-monoclinic-triclinic phase transformation of tet-ZSM-5 structure and the monoclinic-triclinic transformation of cal-ZSM-5 structure were observed.