Effect of calcium ferrites on carbon dioxide gasification reactivity and kinetics of pine wood derived char

Abstract

Biochar gasification is an essential stage of chemical looping biomass gasification, a promising sustainable source of energy that may limit anthropogenic carbon dioxide emissions. Here, the performance of calcium ferrite oxygen carriers (CaFe2O4, and Ca2Fe2O5) on the CO2 gasification reactivity and kinetics of pine wood char is investigated by a thermogravimetric analyzer. The morphology and graphitization degree of the pine wood derived biochar were characterized by using high-resolution transmission electron microscope (HRTEM) and Raman spectroscopy. A random pore model is established and the best matching structural parameter, Ψ, is used to indicate the pore structure of the initial char samples. Results indicate that the activation energy under biochar with no oxygen carrier, biochar loaded with 10 wt% Fe2O3, 10 wt% Ca2Fe2O5, and 10 wt% CaFe2O4 are 169.76 kJ/mol, 176.03 kJ/mol, 173.81 kJ/mol, and 178.83 kJ/mol, respectively. The introduction of oxygen carriers increases the activation energy for CO2 gasification, potentially due to competition with calcium ferrite reduction, resulting in decreased CO2 partial pressure.