Syngas production by chemical looping gasification of biomass with steam and CaO additive

Abstract

In the present work chemical looping gasification (CLG) of biomass, with introduction of steam and CaO, was conducted in a fixed bed to produce syngas. The addition of steam facilitated both the reforming reaction and water gas shift reaction to produce more gaseous products, especially H2. Depending on gas yield and gasification efficiency, the requirement of steam was sufficient for CLG at steam flow n = 0.6 r/min. It was also confirmed that CaO had a positive effect in gasification and the addition in the ratio of CaO/C = 1 was adequate for syngas production. Moreover, CaO mainly played a role as CO2 absorbent at low temperature but as catalyst above 700 °C. However, the catalysis of CaO received the major attention because of its availability for high syngas yield (1.367 m3/kg) and efficiency (carbon conversion efficiency was 89.28% and gasification efficiency was 88.81%) at 800 °C. CaO was found to retard the sintering and porosity reduction of Fe2O3, the oxygen carrier, by covering Fe2O3 and forming calcium ferrites during multiple redox cycles.