Catalytic effect and kinetic mechanism of alkali metal carbonates on the reduction reaction of biochar with iron oxide

Abstract

Previous studies have shown that alkali metals catalyse the pyrolysis and gasification processes of biomass. However, whether alkali metals have the same catalytic effect on the reduction reaction of biochar with iron oxide has not been investigated. In this article, the effect of alkali metals on the reduction behaviour of biochar with iron oxide was investigated. It was shown that adding alkali metal carbonate could increase the reaction rate of CSC reduction stages 1 and 2, but it played an inhibitory role for the first and middle periods of stage 3. Moreover, adding alkali metals resulted in higher total CO₂ gas production and reduced total CO gas production for the reduction reaction. The GB1 model was the best mechanistic model for stages 1 and 2 of the CSC-2K and CSC-2Na reduction reactions, while the C1 model was the best mechanistic model for stage 3.