Ni-Promoted Fe₂O₃/Al₂O₃ for Enhanced Hydrogen Production via Chemical Looping Methane Reforming

Abstract

Chemical looping methane steam reforming shows promise for hydrogen production due to in situ CO2 capture and inherent hydrogen production but is limited by the low reactivity of the oxygen carriers. In this work, we propose several Ni-promoted Fe2O3/Al2O3 to generate hydrogen via chemical looping methane reforming and investigated the origin for the promoted redox performance; 10 wt % NiO–Fe2O3/Al2O3 shows high CH4 conversion (96%), H2 yield (3.3 mmol/g), and low carbon deposition (0.093 mmol/g). DFT calculations demonstrate that metallic Ni can decrease the energy barriers (1.24 eV) for methane activation. Characterizations manifest that 10 wt % NiO–Fe2O3/Al2O3 can significantly increase the reduction depth of Fe2O3, thus providing more oxygen vacancies for hydrogen production. A further increase in Ni content would decrease the oxygen capacity, reducing the potential for hydrogen production. Therefore, the enhanced redox performance of 10 wt % NiO–Fe2O3/Al2O3 results from the ability of Ni to facilitate CH4 activation, improving the reduction of Fe2O3 without significantly improving carbon deposition. We anticipate that the synergy between Ni and Fe2O3 can lead to the development of highly active and stable oxygen carriers.

Carbon Dioxide Capture and Hydrogen Production with a Chemical Looping Concept: A Review on Oxygen Carrier and Reactor

“…From a thermodynamic point of view, reactions – are favorable, while reactions – are opposite. This means that the deep reduction product (metallic Fe) can recover part of the lattice oxygen in the oxidizer to generate Fe 3 O 4 and further can completely regenerated Fe 2 O 3 through air oxidation. , Therefore, the Fe 2 O 3 OC is very suitable for chemical looping steam reforming to produce H 2 . Previously, researchers used the high activity of Fe-based OC for water splitting, combined with the excellent activation performance of Ni-based OC for CH 4 , developed Fe–Ni oxygen carrier for hydrogen production in CLSR process, thus obtaining H 2 yield of 28.2 mol/kg OC and 97.5% CH 4 conversion .…”