Tuning the Support Properties toward Higher CO2 Conversion during a Chemical Looping Scheme

The chemical looping process is promising for CO2 conversion because of the much higher CO2 conversion efficiency than the photocatalytic and electrocatalytic processes. Conventional oxygen carriers have to include a high content of inert support, typically Al2O3, to avoid sintering, thus leading to...

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Bibliographic Details
Published in:Environmental science & technology 2020-10, Vol.54 (19), p.12467-12475
Main Authors: Zeng, Dewang, Qiu, Yu, Ma, Li, Li, Min, Cui, Dongxu, Zhang, Shuai, Xiao, Rui
Format: Article
Language:English
Subjects:
Aluminum oxide
Carbon dioxide
Conductivity
Energy and Climate
Ferric oxide
Gadolinium
Oxygen
Redox reactions
Splitting
Stability
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Summary:The chemical looping process is promising for CO2 conversion because of the much higher CO2 conversion efficiency than the photocatalytic and electrocatalytic processes. Conventional oxygen carriers have to include a high content of inert support, typically Al2O3, to avoid sintering, thus leading to a trade-off between reactivity and stability. Here, we propose the use of ion-conductive Gd x Ce2–x O2−δ (GDC) to prepare the supported oxygen carriers. The resulting Fe2O3/GDC materials achieve both high reactivity and stability. Fe2O3/Gd0.3Ce1.7O2−δ shows high CO productivity (∼10.79 mmol·g–1) and CO production rate (∼0.77 mmol·g–1·min–1), which are twofold higher than that of Fe2O3/Al2O3. The performance remains stable even after 30 cycles. The mechanism study confirmed the rate-limiting role of the oxygen-ion conductivity, and the GDC support enhanced the oxygen-ion conductivity of oxygen carriers during the redox reactions, thus leading to improved CO2 splitting performance. A roughly linear relationship between the oxygen-ion conductivity and CO2 yield is also obtained and verified in our testing conditions. This relation can be used to predict and select oxygen carriers with high CO2 splitting performance.
ISSN:0013-936X
1520-5851
DOI:10.1021/acs.est.0c01702