(350d) Numerical Study of Particle Dynamics during Flame Spray Synthesis of Nanoparticles

A numerical study of a process, such as flame spray pyrolysis (FSP), in which many different phenomena take place simultaneously, is important in order to gain insight in the characteristics of the final product. The properties of the synthesized particles depend on the composition, structure and size of agglomerates/aggregates and constituent primary particles [1]. Hence, the description of their evolution within the highly reactive and turbulent flame environment is of major importance for nanoparticle production by FSP. In this regard, population balance models (PBM) have been considered as an effective tool for the simulation of nanoparticle dynamics [2].

In the present study, modelling of particle dynamics during FSP is performed assuming that there is no surface growth. Monomers are formed by instantaneous chemical reactions and grow to clusters and particles due to collisions. As FSP is a complex process, mainly because of formation and growth of particles by agglomeration/aggregation and sintering, a bivariate population balance equation is solved by the quadrature method of moments (QMOM) that better describes the particle population [3]. This approach takes into consideration polydispersity of the produced particles. Particle number concentration, sintering rate and residence time of nanoparticles are calculated and the obtained results are compared with results from the monodisperse model of Kruis et al. [4], which describes the size distribution by its mean value. The obtained size values are compared with experimental data by nitrogen adsorption measurements. Coupling the control of growth processes with accurate characterization tools and modelling approaches is prerequisite for process scale-up and consequently development of high-performance materials.

References

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2. Tsantilis T., Kammler H.K., Pratsinis S.E., Population balance modeling of flame synthesis of titania nanoparticles. Chemical Engineering Series 2002;7:2139-2156.
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4. Kruis F.E., Kusters K.A., Pratsinis S.E., Scarlett B., A Simple Model for the Evolution of the Characteristics of Aggregate Particles Undergoing Coagulation and Sintering. Aerosol Science and Technology 1993;19:514-526.