Reaction performance of Ce-enhanced hematite oxygen carrier in chemical looping reforming of biomass pyrolyzed gas coupled with CO2 splitting

Hematite enhanced by CeO2 were investigated in chemical looping reforming (CLR) coupled with CO2 splitting to achieve high quality synthesis gas and recycle CO2 into CO. CeO2, Fe2O3 and CeFeO3 solid solution generated from integration of Fe3+ and CeO2 lattice were detected in mixed oxygen carriers as major components. Owing to the charge compensation and oxygen defects formation in lattice rearrangement, CeFeO3 solid solution contributed to promoting oxygen mobility and creating oxygen vacancies. Fe2O3 particles helped provide oxygen spillover pathway from subsurface to surface and improve lattice oxygen transfer through direct contact with the surface of CeFeO3 solid solution. CeO2 enhanced metallic interaction and catalytic oxidation reactivity. The highest gas product amount and H-2/CO in CLR process increased by 43.46% and 51.31%, respectively. Also, the instantaneous CO productivity of 2.47 mmol/min/g with 86.13% CO2 conversion was realized in CO2 splitting. Reaction parameters including temperature, CeO2 content and MCO2/mOC indicated positive correlation with CO productivity. The mixed oxygen carrier maintained its reactivity and stability after 15 cycles reaction following the pathway of Ce2O3/Fe2O3/CeFeO3/Ce2O3/Fe/CeFeO3/CeO2/Fe3O4, though sintering behavior was observed in reacted sample. FeeCe interactions and oxygen mobility were improved by successive redox reactions, which can offset the negative effects of sintering. (C) 2020 Published by Elsevier Ltd.

Automated summary

Hematite enhanced by CeO2 in chemical looping reforming (CLR) showed a promotion in oxygen mobility and creation of oxygen vacancies, contributing to high quality synthesis gas production and CO2 conversion into CO. Adjustment of reaction parameters can enhance CO productivity, and the mixed oxygen carrier maintained stability after 15 cycles of reaction.