Process design for gas-phase synthesis of iron nanoparticles from iron pentacarbonyl

Abstract

Gas-phase synthesis of iron nanoparticles (Fe NPs) by thermal decomposition of iron pentacarbonyl, ${\text{Fe}\left(\text{CO}\right)}_5$, is simulated using a simple particle dynamics model coupled with gas-phase chemistry. The performance of a detailed chemical kinetics model for the decomposition of ${\text{Fe}\left(\text{CO}\right)}_5$ is compared with that of a global decomposition rate. The particle dynamics model interfaces with gas-phase chemistry through particle inception and surface growth. Using the size-dependent melting temperature of primary particles (PP), the available characteristic sintering time, ${\tau }_s$, for Fe NPs is modified and its performance in predicting PP diameter, $d_p$, is benchmarked with literature data. The modified ${\tau }_s$ significantly enhances the prediction of $d_p$ and agglomerate morphology, highlighting the importance of sintering during high temperature synthesis of Fe NPs. Diagrams for the degree of hard-agglomeration are developed in terms of the reactor initial precursor concentration, maximum temperature, cooling rate, and particle residence time. The results of the PP size of Fe agglomerates are compared with TEM measurements available in the literature for the synthesis of Fe NPs. The model predictions are in good agreement with the measured $d_p$ and concentration of Fe NPs produced by thermal decomposition of ${\text{Fe}\left(\text{CO}\right)}_5$.