Evaluation of Fe substitution in perovskite LaMnO3 for the production of high purity syngas and hydrogen.

Chemical looping reforming of methane (CLRM) technology is a new approach for syngas and pure hydrogen generation. During the whole reaction, methane is first partially oxidized to syngas by the lattice oxygen of the oxygen carrier, and then the lattice oxygen of the reduced oxygen carrier is recovered by thermal water splitting, with pure hydrogen produced. LaMnO 3 is used as an oxygen carrier for the CLRM. It obtains a high resistance to carbon deposition, while a lower CH 4 conversion due to the unstable structure. Fe ion substitution in LaMnO 3 can be used to improve its reactivity and thermal stability. La 1-x MnFe x O 3 /LaMn 1-x Fe x O 3 (x = 0.05, 0.1, 0.15, 0.2) oxygen carriers own higher reactivity and better resistance to carbon deposition, producing high purity syngas and hydrogen. La 0.85 MnFe 0.15 O 3 sample exhibits the highest CO selectivity (~99%), syngas productivity (3.78 mmol g−1) and H 2 productivity (1.76 mmol g−1) due to the higher oxygen vacancy concentration, and its H 2 /CO molar ratio is maintained at the ideal ratio of 2.0 (1.93–2.07) during the whole process. Notably, no carbon deposition is generated over LaMnO 3 , La 0.85 MnFe 0.15 O 3 and LaMn 0.9 Fe 0.1 O 3 oxygen carriers even after 20 redox cycles, and La 0.85 MnFe 0.15 O 3 exhibits superior resistance to carbon deposition due to the better structural and thermal stability. Image 1 • The doping of Fe to LaMnO 3 promotes the production of syngas and pure hydrogen. • La–Mn–Fe–O oxygen carriers possess higher reactivity and ideal H 2 /CO molar ratio. • La 0.85 MnFe 0.15 O 3 exhibits the optimal performance during 20 redox cycles. [ABSTRACT FROM AUTHOR]