Reversible oxygen intercalation in hexagonal Y_0.7Tb_0.3MnO_3+δ: toward oxygen production by temperature-swing absorption in air

Abstract

The oxygen storage capacity, oxygen exchange kinetics, structure and thermodynamic stability were studied for hexagonal Y0.7Tb0.3MnO3+δ in oxygen and air to assess its applicability for oxygen separation from air by a temperature-swing adsorption process.

Oxygen separation from air by the combined temperature swing and pressure swing processes using oxygen storage materials Y1−x(Tb/Ce)xMnO3+δ

“…800°C in Ar corresponds to the oxygen-stoichiometric composition. The Hex0 phase (d & 0) of hexagonal oxides is stable at high temperatures, as it was already documented in all other papers devoted to studies of this class of materials [23,[31][32][33]. Because the substituted cerium tends to have ?4 oxidation state in air, the considered compounds show rather a mixture of the oxidized Hex1 and Hex0 phases, unless properly reduced, e.g., in Ar (Table 1).…”

“…Comparing the published structural data for nearly oxygen-stoichiometric YMnO 3 [31] and the Tb 3? -for-Y 3?…”

“…As-synthesized Y 0. . Since the oxygen intake/release proceeds with many steps, and it also involves adsorption/desorption and reduction/oxidation, and therefore, the highly developed surface through which the process proceeds improves the kinetics of the observed reactivity with oxygen [31]. If materials possess similar BET specific surface areas, the differences in the measured kinetic characteristics can be interpreted to arise mainly from the difference in the chemical composition of the compounds.…”

“…The recently reported hexagonal YMnO 3?d compound and its derivatives (Y 1-x R x MnO 3?d , R: other than Y rare earth elements) showed superior results in terms of the operating temperatures. Especially in the case of Y 0.7 Tb 0.3 MnO 3?d , very encouraging results have been obtained with T oxy-& 270°C in air with practical DT = 60°C, while in oxygen the respective T oxy & 300°C and T red-& 350°C were required [31]. Substitution of Tb into YMnO 3?d allowed to significantly increase the maximum oxygen content in the oxidized phase, up to ca.…”

“…The route utilized in this study enables synthesis at relatively low temperatures in comparison with the standard solid-state reaction method [32,38]. More details regarding the preparation procedure can be found elsewhere [31][32][33].…”