Chemical Looping Gasification of Torrefied Biomass Using NiFe2O4 as an Oxygen Carrier for Syngas Production and Tar Removal

The aim of this study was to investigate the effect of torrefaction severity and ratio of the oxygen carrier to feedstock on syngas production and tar removal during chemical looping gasification of eucalyptus using NiFe(2)O(4)as an oxygen carrier. Torrefaction of eucalyptus was conducted in a fixed bed reactor with varying torrefaction temperatures and residence times. The chemical looping gasification of torrefied eucalyptus and its derived char using NiFe2O4 as an oxygen carrier was systematically investigated by thermogravimetric analysis-mass spectrometry and analytical pyrolysis-gas chromatography/mass spectrometry. The results showed that torrefaction of eucalyptus can improve its char reactivity and reduce tar formation during chemical looping gasification. In addition, the optimal torrefaction severity of eucalyptus for chemical looping gasification was 280 degrees C with a residence time of 40 min. Furthermore, the chemical looping gasification of eucalyptus torrefied at 280 degrees C with a varying mass ratio of NiFe2O4 to feedstock was carried out in a fixed bed reactor to verify the possibility of obtaining clean syngas. The results demonstrated that the optimal mass ratio of NiFe2O4 to feedstock for chemical looping gasification of torrefied eucalyptus was 1.25. Chemical looping gasification of torrefied eucalyptus at this condition can achieve the highest total gas yield of 1.05 Nm(3)/kg and the lowest tar content of 3.5 g/Nm(3). These findings provide a novel and efficient method to obtain clean syngas production with low tar content from biomass.