(113f) Modeling Size and Morphology Evolution of Multiparticle Aggregates during Simultaneous Reaction and Sintering

The size and morphology of nanosized aggregates play a crucial role in determining their performance in several applications, including healthcare, energy storage, and catalysis. Thus, knowledge and control of processes that determine the primary particle size and morphology of aggregates is crucial to synthesizing nanomaterials of optimal performance. Both the size and morphology are impacted by several aerosol mechanisms, including sintering. Many systems in which sintering occurs also undergo concomitant inter/intra-particle processes such as coagulation, growth, and chemical reaction. Numerical models have successfully addressed this challenge for scenarios involving simultaneous coagulation and sintering as well as growth and sintering; however, to the best of our knowledge, scenarios with simultaneous reactions and sintering have not been addressed.

In the present study, a novel geometric model (GM) is developed to predict the evolution in size and morphology of multiparticle aggregates under simultaneous sintering and chemical reactions. The GM enables the estimation of sintering kinetics to predict changes in primary particle size, neck size, and surface area of aggregate as a function of residence time and temperature. Lignin, the second most abundant aromatic biopolymer, is used as a model compound and a furnace aerosol reactor system is then used to study the evolution of lignin nanoparticles that are impacted by sintering and reaction. Using the developed model, kinetic parameters for sintering and reaction are determined by comparing GM to the experimental results. The kinetic parameters for lignin reaction agreed well with literature-reported values. The kinetic parameters for lignin sintering, which are the pre-exponential factor and activation energy, were estimated as 6.6x10^-8 s.nm^-1 and 116.4 kJ.mol^-1, respectively. The lignin sintering rate parameters were effectively used to establish the impact on the synthesis of lignin-based high-value products, specifically nanomaterials and bio-oil. The developed GM is simple and generalizable to investigate the size and morphology changes of other materials that undergo reactions with sintering.

Reference:

S. Modi, O. Okonkwo, H. Zhou, S. Kavadiya, M. Foston, P. Biswas, Geometric Model for Predicting the Size and Morphology Evolution of Multiparticle Aggregates during Simultaneous Reaction and Sintering, Chem. Eng. J. (2023) 141423.