The rational design of oxygen carriers (OCs) is critical for enhancing biomass chemical looping gasification (BCLG) performance. This work systematically investigated the effects of different supports (Al2O3, ZrO2, TiO2, SiO2) on the performance of NiFe-based OCs with oxidation and catalytic reforming functions. The gasification reactivity and support-active phase interaction of OCs in both oxidized and reduced states were evaluated. XRD, H2-TPR, XPS, and SEM techniques were employed to characterize the phase composition, synergistic interactions, and surface morphology. The results showed that NiFeAl exhibited the optimal gasification performance in both oxidized and reduced states, achieving a syngas (H2 + CO) yield of approximately 1.4 m3/kg (dry walnut shell). NiFeAl featured a higher Fe binding energy, abundant cavity structures, and the uniform dispersion of Ni and Fe on Al2O3, which confirm the formation of an appropriately strong Ni-Fe-Al ternary system. In contrast, NiFeZr suffered from the higher CO2 yield, attributed to the over-oxidation caused by the weak interactions. NiFeTi and NiFeSi had lower syngas yields due to their poor reducibility induced by excessively strong interactions. This work verifies that moderate support-active phase interactions in OCs are optimal for BCLG.
Chen et al. (Thu,) studied this question.