Pyrolysis kinetics-dependent suitability of Al-based MOFs (CAU-10) for controlling amorphous γ-Al2O3 generation

Abstract

The thermal degradation of Al-based MOF (CAU-10) were analyzed based on an isoconversional calculation method. The ɤ-Al 2 O 3 formation were characterized using XRD, FTIR, 27 Al NMR-MAS and SEM/EDX. The apparent activation energy E a was evaluated using the iterative isoconversional method. The values of these energies related to the first step (deshydration) and the second step (framework destruction) for the thermal decomposition of CAU-10 reached 35 and 217 kJ/mol, respectively. This indicates that the second step is a complex kinetic process. In addition, the kinetic processes occur in a single step and can be characterized by a unique kinetic triplet (Ea, A, g(α)). For both decomposition steps of CAU-10, the mechanism includes chemical reactions, nucleation, branched nuclei, and three-dimensional diffusion in the first and second phases. According to the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa ( FWO) models in the first step, the Gibbs free energy is between 91.099 kJ/mol and 97.824 kJ/mol; between 242.651 kJ/mol and 244.285 kJ/mol, respectively. This analysis based on thermal measurements combined with structural measurements has highlighted the energetic potential of MOFs synthesis from aluminum exposed to a vapor explosion in a basic context.