Kinetic model for transformation from nano-sized amorphous $TiO_2$ to anatase
McCoy, Benjamin J
- Publisher: American Chemical Society
We propose a kinetic model for the transformation of nano-sized amorphous $TiO_2$ to anatase with associated coarsening by coalescence. Based on population balance (distribution kinetics) equations for the size distributions, the model applies a first-order rate expression for transformation combined with Smoluchowski coalescence for the coarsening particles. Size distribution moments (number and mass of particles) lead to dynamic expressions for extent of reaction and average anatase particle diameter, which are compared with experimental data [Chem. Mater. 2002, 14, 4145]. Data at different temperatures yield activation energies for coalescence and transformation rate coefficients, as well as an overall endothermic transformation energy for combined transformation and dehydration.