Geometric model for predicting the 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. Both the size and morphology are impacted by several aerosol mechanisms, including sintering. Studies have reported the role of sintering combined with other aerosol mechanisms such as collisional growth. Many systems in which sintering occurs also have a concomitant chemical reaction. In this study, a novel geometric model (GM) is developed to predict the evolution in size and morphology of multiparticle aggregates under simultaneous sintering and chemical reaction. 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.