Crystallization mechanism and catalytic properties with amount of the precipitated CePO4 for cerium phosphate glass catalyst

Abstract

The crystallization kinetics and catalytic properties with amount of precipitated CePO4 of a 60P2O59B2O324ZnO7CeO2 glass was investigated. The kinetic parameters, activation energy for crystallization (Ec), and Avrami constant (n) were evaluated under non-isothermal conditions using different thermal analysis (DTA) performed at different heating rates. The DTA curves exhibited two overlapping exothermic peaks associated with the crystallization of the glass. BPO4 was the first crystalline phase to be formed, and it was followed by the formation of CePO4, as identified by XRD. The calculated values of the local activation energies for the growth of BPO4 were 663 kJ mol11, obtained using the Kissinger method, and 669 kJ mol11, obtained by the Marotta method. The calculated values of the local activation energies for the growth of CePO4 were 452 kJ mol-1, obtained by Kissinger method, and 464 kJ mol-1, obtained by the Marotta method. The Avrami constants of BPO4 and CePO4 were 1.832.56 and 1.401.54, respectively. The catalytic properties with the amount of precipitated CePO4 were studied by thermogravimetric analysis (TGA), which showed that the greater the amount of CePO4 precipitated, the more the catalytic properties of the glass decreased.