Reduction Kinetics of Perovskite-Based Oxygen Carriers for Chemical Looping Combustion

Abstract

LaMnO3 and LaMnO3@mSiO2 oxygen carriers were studied in a mini-fluidized bed reactor for chemical looping combustion, and their reduction behavior was first simulated using the following two classical kinetic models: the nucleation and nuclei growth model (NNGM) and the unreacted shrinking-core model. Furthermore, another model designated as the oxygen ions diffusion model was derived by assuming oxygen ion diffusion as the rate-limiting step for the reduction of both oxygen carriers. These materials were characterized using XRD for phase identification, BET for determination of specific surface area, pore volume and pore size distribution, SEM and TEM for morphology, particle size and shell thickness determination, H2-TPR and TPD-O2 for oxido–reduction properties analysis. H2-TPR results of LaMnO3@mSiO2 core–shell structured material indicated that the reduction of Mn3+ into Mn2+ is more difficult than in LaMnO3 as the low-temperature reduction peak was shifted to a higher temperature. Both carriers exhi...