“…Therefore, in Fe 2 O 3 -(SG+AD), the Fe catalyst reacted at a relatively low temperature. A similar result was reported in Zhang et al's study [18], in this case, iron catalyst was considered to be coordinated to a range of oxygen-containing ligands in coal or biomass, including O 2 − , OH − , and COO − , which were generally associated with tar precursors. In our study, SG produced a large amount of tar during pyrolysis, this may be an important reason why the difference appeared after SG added.…”