Improved cyclic redox reactivity of lanthanum modified iron-based oxygen carriers in carbon monoxide chemical looping combustion

Abstract

Improved cyclic redox reactivity of low concentration La-doped iron-based oxygen carriers in CO combustion with a chemical looping concept.

Advances in Carbon Management Technologies

“…Li was selected as the dopant because of its high catalytic function in OCM and its similar ionic radius to Mg (Ito and Lunsford, 1985). However, a high Li-dopant concentration may modify the crystal phases of the oxygen carrier which, in turn, leads to a decrease of the oxygen carrying capacity of the oxygen carrier (Qin et al, 2017). Thus, the Li dopant concentration was controlled at a low value of around 1%.…”

Driving Towards Highly Selective and Coking‐Resistant Natural Gas Reforming Through a Hybrid Oxygen Carrier Design

“…The nature of lattice oxygen mediated chemical looping technology is redox reactions involving methane molecules absorption and CÀ H bond dissociation on metal-oxide based oxygen carrier surfaces, lattice oxygen ion diffusion, oxygen vacancy creation and annihilation at high temperatures. [23,24] The state-of-the-art process design has achieved an overall chemical looping operation over 3000 cycles. [25] One key challenge in chemical looping process is to improve the catalytic reactivity of oxygen carrier in activating the CÀ H bond significantly.…”

“…Nevertheless, the reactivity of FO to methane is low to moderate at temperatures below 900°C. [19,39,40] In this work we develop a hybrid LFO-FO material that fuses the advantages of LFO and FO together by utilizing a low concentration of LFO as the active component and a high concentration of FO as a dynamic oxygen reservoir. Atomistic level understanding of CH 4 activation and carbon dissipation/deposition on LFO obtained from density functional theory (DFT) calculations guides the design concept of hybrid LFO-FO oxygen carriers.…”

“…By preventing the direct contact between methane and air, a highly concentrated product stream can be collected which eliminates the energy‐intensive penalty for downstream gaseous product purification. The nature of lattice oxygen mediated chemical looping technology is redox reactions involving methane molecules absorption and C−H bond dissociation on metal‐oxide based oxygen carrier surfaces, lattice oxygen ion diffusion, oxygen vacancy creation and annihilation at high temperatures [23,24] . The state‐of‐the‐art process design has achieved an overall chemical looping operation over 3000 cycles [25] .…”

“…On the other hand, hematite Fe 2 O 3 (FO) has long been considered as a promising material for commercialized oxygen carrier due to its high oxygen carrying capacity, stable structure, low cost, and low environmental impact. Nevertheless, the reactivity of FO to methane is low to moderate at temperatures below 900 °C [19,39,40] . In this work we develop a hybrid LFO‐FO material that fuses the advantages of LFO and FO together by utilizing a low concentration of LFO as the active component and a high concentration of FO as a dynamic oxygen reservoir.…”