Natural Iron Ore as Oxygen Carrier Modified with Rare Earth Metal for Chemical Looping Hydrogen Production
Haiming Gu, Xiaobo Cui, Jian‐Qiang Wang, Wanqi Li, Xuyang Wu, Liang Wang, Shanhui Zhao, Zhenghui Qiao, Miaomiao Niu
Abstract
Chemical looping hydrogen production (CLHG) represents a novel technology for H2 production. Natural iron ore is a potential oxygen carrier for CLHG but is facing a challenge of low deep reduction reactivity. This paper aims at promoting the reduction reactivity of iron ore and H2 production using Ce-doped and La-doped iron ore with an impregnation method. The oxygen carriers were characterized by SEM-EDX, XRD, and XPS. The reactivity and stability of the doped iron ore were evaluated in TGA. The CLHG process was carried out in a fixed bed system, and the effect of rare earth metal on oxygen carrier conversion and H2 production was evaluated. The results indicate that both Ce-doped and La-doped iron ore as oxygen carriers exhibited a higher reduction reactivity than the raw iron ore and a relatively stable redox performance at 900 °C after the initial activation process. Reasonable Ce loading (5–10%), La loading (2.5–15%), and temperature (above 850 °C) could promote oxygen carrier conversion and enhance H2 production. The La-Fe interaction enabled the iron ore to be oxidized to LaFeO3 (Fe3+) during water splitting, promoting H2 production. Carbon deposition was not formed during the reduction process, and H2 purity remained at 100% during the whole water splitting process.