Improving the carbon resistance of iron-based oxygen carrier for hydrogen production via chemical looping steam methane reforming: A review

Chemical looping steam methane reforming (CL-SMR) is a promising and efficient technology for generating high-purity hydrogen with low energy penalty and minimum carbon footprint. As the key for CL-SMR process, oxygen carriers (OCs) constructed by iron-based oxides have attracted particular attention these years due to the inexpensive and environmentally friendly features. However, these OCs are prone to carbon deposition during methane atmosphere due to insufficient oxygen mobility, which in turn renders limited hydrogen yield or lowered hydrogen purity due to contamination by formed carbon monoxide in water splitting process. This work analyzes the mechanism for coke deposition with special emphasis on the strategies in improving the carbon resistance of iron-based OCs, including natural iron ores, supported iron oxides, spinel, perovskite, hexaaluminate, and garnet etc. It is anticipated that the discussion presented here would provide valuable guidance for designing perspective OCs for CL-SMR process.