Use of CuO/MgAl2O4 and La0.8Sr0.2FeO3/gamma-Al2O3 in Chemical Looping Reforming System for Tar Removal from Gasification

Biomass gasification gas contains condensable hydrocarbons usually referred to as "tars." The use of chemical-looping reforming (CLR) has been proposed as a downstream technology for tar removal. The tar removal capabilities and the regeneration properties of two particularly promising bed materials, CuO/MgAl2O4 and La0.8Sr0.2FeO3/gamma-Al2O3, were investigated using C2H4, C6H6, and C7H8 as tar surrogates. The material La0.8Sr0.2FeO3/gamma-Al2O3 exhibited high levels of conversion of all tar surrogates investigated, whereas CuO/MgAl2O4 showed less promising behavior. For this material, the C2H4 conversion in the absence of aromatic compounds was very high, but in the presence of monoaromatic compounds, the conversion of aromatics and C2H4 was poor. This indicates that monoaromatic compounds hinder the conversion of C2H4 effectively. Therefore, C2H4 may not always be a good choice as a tar surrogate and its suitability may depend on the mechanism of hydrocarbon conversion on the bed material surface in question