Study on the reaction characteristics of tar model compounds with an Fe-based oxygen carrier

This work investigated the conversion characteristics of iron-based oxygen carrier (70%Fe₂O₃/30% Al₂O₃) with TMCs in a two-stage fixed-bed reactor using tar model compounds (TMCs) of biomass/coal, and evaluated the reactivity of different TMCs and the factors affecting their conversion. It was found that the reaction degree of TMCs with oxygen carrier was phenol>anthracene>naphthalene, and the conversion of phenol to carbon deposition was the highest (64%), while the conversion of naphthalene to carbon deposition was the lowest (40%); the degree of reaction between oxygen carriers and naphthalene was relatively high, but easily led to the sintering of oxygen carrier. Besides, activity characterization of the carbon deposition showed that the carbon deposition generated from naphthalene had the highest stability among the three TMCs. Increasing the amount of oxygen carrier and reaction temperature was beneficial to the further conversion of naphthalene and anthracene, and could also increase the fraction of CO₂ in gaseous products. The high reaction activity and strong cracking effect of phenol led to a small change in the conversion rate with increasing the amount of oxygen carrier and reaction temperature. However, high reaction temperature (1000 ℃) could lead to severe cracking of the tar to generate a large amount of carbon deposition. The results of the cycle experiment showed that the oxygen carrier reacting with naphthalene was most severely deactivated.