Air separation and selective oxygen pumping via temperature and pressure swing oxygen adsorption using a redox cycle of SrFeO3 perovskite

Isothermal relaxation kinetics for the reduction and oxidation of SrFeO3 based perovskites

“…where m is the sample mass, M O is the molar mass of molecular oxygen and M sample is the molar mass of the sample at the reference point. The reference point was T = 803 K and p O 2 = 1 bar, with two previous studies on the SrFeO 3Àd perovskite system indicating that this reference point corresponds to SrFeO 2.77 , 4,6 giving M sample = 187.78 g mol À1 . For SCFCO, the oxygen nonstoichiometry at the reference point was assumed to be the same as SrFeO 3 .…”

“…The oxygen non-stoichiometry d, decreases with temperature, 3 but has been found to persist at relatively low temperatures, T o 673 K. 4 For this reason SrFeO 3 based perovskites have been extensively investigated as oxygen storage materials, which can be utilized in oxygen separation and production processes. [5][6][7][8] These processes operate via a redox cycle, where oxygen is absorbed in an oxidation step and released again in a reduction step. They can use a temperature swing, 9 and/or a pressure swing, [10][11][12] to switch between oxidation and reduction of the oxide.…”

“…However, lower temperatures will also hinder the kinetic activity of the redox reaction. Isothermal relaxation experiments on reduced SrFeO 3 powder have shown rapid oxidation kinetics for temperatures above 673 K, 16 where thermodynamic equilibrium was reached in approximately 1-2 min at 723 K. 6,16 However, at 523 K 300 hours was insufficient time for a dense disk of the reduced perovskite SrFeO 2.5 to reach equilibrium. 4 These results suggest that oxidation reaction kinetics can become a critical limitation for temperatures below 723 K.…”

A‐ and B‐site Codoped SrFeO3 Oxygen Sorbents for Enhanced Chemical Looping Air Separation

“…Chemical‐looping air separation (CLAS) represents another promising approach for air separation . Based on the redox chemistry of metal oxides, high‐purity oxygen can be produced when the oxide is heated at high temperature or exposed to low oxygen partial pressure . After releasing oxygen, the reduced metal oxide can be re‐oxidized by exposure to air to store the oxygen as O 2− in the lattice.…”

Sr1-xCaxFe1-yCoyO3-δ as facile and tunable oxygen sorbents for chemical looping air separation

“…By oxygen partial pressure swing between air and helium at 600 • C,~1 wt% oxygen capacity was achieved for oxygen production [39]. Recently, SrFeO 3 based oxygen sorbents have received many research interests, owing to its large oxygen capacity and low operating temperature [40][41][42]. The versatile structure of SrFeO 3 offers many opportunities to introduce dopants at A and/or B site to further tuning the redox property [43][44][45].…”