Enhanced oxygen intake/release kinetics of BaYMn2O5+.DELTA. fine powders prepared by a wet-chemical route

Abstract

The effect of grain size on the oxygen intake/release kinetics were investigated for double-perovskite type BaYMn 2 O 5+¤ (¤ = 0.0 1.0). The preparation of BaYMn 2 O 5+¤ with larger specific surface area was achieved by low-temperature firing (down to 900°C) of precursors obtained from a wet-chemical route. The oxygen intake/release rates at 500°C were found to increase significantly in the resultant BaYMn 2 O 5+¤ fine powders, indicating a key role of the powder surface in the oxygen intake/release processes.

Crystal structure and oxygen storage properties of BaLnMn2O5+δ (Ln: Pr, Nd, Sm, Gd, Dy, Er and Y) oxides

“…7. For reduction of BaGdMn 2 O 6 the oxygen release rate, as defined in work [35], reached 1.6 wt.% min À1 during the 5th reduction, matching the values obtained for the optimized BaYMn 2 O 6 with larger specific surface area. a Data from Ref.…”

“…As can be expected, apart from chemical composition, also grain size and morphology of the powder should have strong influence on the speed of reduction and oxidation [35]. Fig.…”

Redox characteristics variations in the cation-ordered perovskite oxides BaLnMn2O5+δ(Ln = Y, Gd, Nd, and La) and Ca2Al1−xGaxMnO5+δ(0 ≤ x ≤ 1)

“…28 As demonstrated in Fig. S2 of the ESI, all of the Ln-products consist of coarse particles with a similar size of 1 ~ 2 µm, although the grain shape in the La-product is somewhat different from the other products.…”

A determination of the oxygen non-stoichiometry of the oxygen storage material YBaMn2O5+

“…Based on the previous work, the possibility of using YBaMn 2 O 5 þ δ in a chemical looping application gave us an interest in further studying this system. The oxygen uptake/release kinetics of YBaMn 2 O 5 þ δ have been studied by Motohashi et al, who also determined the pO 2 dependence of the inter-conversion of YBaMn 2 O 5.5 and YBaMn 2 O $ 6 by thermogravimetric analysis in the pO 2 range 10-10 5 Pa (10 À 4 to 1 atm) and also the range of composition of 'O 6 ' [22][23][24]. We note also that systems with Y partially or completely substituted with other rare-earth elements (La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, and Er) have been investigated [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44].…”