Technical Report 49, c4e-Preprint Series, Cambridge

Authors: Richard H. West, Matthew S. Celnik, Oliver R. Inderwildi, Markus Kraft*, Gregory J.O. Beran, and William H. Green

Reference: Technical Report 49, c4e-Preprint Series, Cambridge, 2007

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The combustion of TiCl₄ to synthesize TiO₂ nanoparticles is a multi-million tonne per year industrial process. This paper aims to further the understanding of this process. Work towards three aspects of this multi-scale problem is presented herein: gas-phase chemistry, surface chemistry, and the solution of a multidimensional population balance problem coupled to detailed chemical mechanisms.
Presented here is the first thermodynamically consistent mechanism with physically realistic elementary-step rate constants by which TiCl₄ is oxidised to form a stable Ti₂O_xCl_y species that lies on the path to formation of TiO₂ nanoparticles. Secondly, progress towards a surface chemistry mechanism based on density functional theory (DFT) calculations is described. Thirdly, the extension of a stochastic 2-dimensional (surface-volume) population balance solver is presented. For the first time the number and size of primary particles within each agglomerate particle in the population is tracked.
The particle model incorporating inception, coagulation, growth, and sintering, is coupled to the new gas phase kinetic model using operator splitting, and is used to simulate a heated furnace laboratory reactor and an industrial reactor. Using the primary particle information, TEM-style images of the particles are generated, demonstrating the potential utility of first-principles modelling for the prediction of particle morphology in complex industrial systems.

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