A- and B-Site Substituted Lanthanum Cobaltite Perovskite as High Temperature Oxygen Sorbent. 1. Thermogravimetric Analysis of Equilibrium and Kinetics

Abstract

Perovskite samples of the general formula La0.1A0.9Co y Fe1- y O3- δ (where A = Ca, Sr, Ba; y = 0.1, 0.5, 0.9) were synthesized in our laboratory. Further substitution of Sr to a small extent by Ag and complete substitution of La by Sr were also studied. For a fixed perovskite composition (SrCo0.5Fe0.5O3- δ), samples obtained by carbonate coprecipitation and citrate methods of synthesis were compared. Use of helium as the carrier gas produced more weight loss (i.e., higher oxygen vacancy) than nitrogen in all the perovskite samples. Oxygen sorption equilibrium and sorption kinetics were thermogravimetrically studied in the temperature range 500−800 °C at atmospheric pressure using oxygen−nitrogen mixtures in which the oxygen fraction ranged from ∼5 to 50%. Desorption kinetics were studied by allowing the equilibrated sample to desorb in pure nitrogen. For a fixed B-site substitution, oxygen capacity varied with A-site substitution in the order Sr > Ba > Ca. Considering both equilibrium capacity and sorption−desorption kinetics, SrCo0.5Fe0.5O3- δ and La0.1Sr0.8Ag0.1Co0.5Fe0.9O3- δ were found to be the more promising candidates for further investigation.

Effect of A-/B-site Doping on Oxygen Non-Stoichiometry, Structure characteristics, and O2 Releasing Behavior of La1−xCaxCo1−yFeyO3−δ Perovskites

“…Recently, perovskites have been extensively studied in applications like solid oxide fuel cells, oxygen-permeable membranes, gas sensors, catalysts, and photocatalytic materials [6][7][8][9]. Perovskite-type metal oxides have the general formula ABO 3 ; if A and/or B sites are substituted with lower valent cations, some oxygen ions are removed from the lattice in order to maintain charge neutrality, thereby giving rise to oxygen non-stoichiometry [10]. Perovskite metal oxides exhibit extremely high selectivity for oxygen due to the existence of oxygen vacancy.…”

Copper aided exchange in high performance oxygen production by CuCo binary oxides for clean energy delivery

“…13,14 Studies from the US Department of Energy indicate that inorganic membranes could reduce the cost of oxygen production by 35%, 15 an important techno-economic aspect of cost reduction in carbon capture and storage processes. 30,31 In principle, stable perovskite materials sorption and desorption cycles generally have slow kinetics due to large temperature swings and their prospect as air separation units is not attractive. 19,20 However, perovskites tend to decompose in the presence of CO 2 leading to the formation of carbonates.…”

Investigation of precursors in the preparation of nanostructured La0.6Sr0.4Co0.2Fe0.8O3−δ via a modified combined complexing method

“…LSCF and related perovskites have been synthesized by numerous methods [10][11][12][13][14][15][16]. Among them, the Pechini method has attracted extensive attention [10][11][12][13].…”