Modeling the precursor utilization in atomic layer deposition on nanostructured materials in fluidized bed reactors

We present a multiscale dynamic model as a means of understanding and optimizing the precursor utilization during atomic layer deposition (ALD) on nanoparticles and micron-sized nano-porous particles in fluidized bed reactors. We used as case study the deposition of alumina using trimethylaluminum and water on both, titania nanoparticles and micron-sized nano-porous γ-alumina particles under low (∼1 mbar) and atmospheric pressure. In doing so, we assess the effect of the precursor transport, from the inlet of the reactor to the particles active surface, on the precursor utilization efficiency. Our results show that, at proper operating conditions, fast ALD reaction kinetics enables the saturation of the particles surface area with hardly any loss of precursors. Finally, simple scaling rules for the optimization of the precursor utilization are proposed.