Theoretical Study on Reactivity of Fe-Based Oxygen Carrier with CH₄ during Chemical Looping Combustion

Abstract

The mechanism of interaction between CH4and oxygen carrier surface was studied using density functional theory (DFT) calculations. The adsorption energy of CH4on Fe2O3surface Fe bridge site is the highest, indicating Fe bridge site adsorption is the most stable, and O top site follows. The CH4-Fe2O3surface reaction path was inferred as: (1) the generation of hydroxyl radical, (2) the interaction between hydroxyl radical and CH4with its intermediates in chain, and (3) the generation of H2O and CO2through oxidation. The research will provide guidance for the interaction mechanism between CH4and oxygen carrier surface and the optimization of CLC macroscopic reaction kinetics.

Methane adsorption and dissociation on iron oxide oxygen carriers: the role of oxygen vacancies

“…Although the CH 4 dissociation mechanism for various materials has been widely studied, [36][37][38][39] there are few reports on the CH 4 dissociation mechanism on iron oxide. Wang et al 40 have used the density functional theory (DFT) method to investigate the interaction between CH 4 and Fe 2 O 3 but they only used a Fe 2 O 3 cluster model and did not include the oxygen vacancies in their system. No work has been reported on the effect of Fe 2 O 3 vacancies on CH 4 and CH x radical adsorption and the corresponding CH 4 dissociation mechanism as far as we know.…”

Recent advances on first-principles modeling for the design of materials in CO2 capture technologies

“…Methane decomposition mechanisms on Fe 2 O 3 have been studied using DFT by multiple groups. Different reaction pathways have been established on Fe 2 O 3 surfaces [74], [75], [76]. Due to the complexity of methane decomposition paths, this reaction mechanism is still under debate and will likely be the subject of future research studies in this area.…”