Oxygen separation from air by the combined temperature swing and pressure swing processes using oxygen storage materials Y1\u2212x(Tb/Ce)xMnO3+\u03b4

Alicja Klimkowicz,Bogdan Dabrowski,Konrad Świerczek,Takao Hashizume,Kacper Cichy,Teruki Motohashi,Sayaka Tamura,Akito Takasaki

doi:10.1007/s10853-020-05158-5

Abstract

Hexagonal Y1−xRxMnO3+δ (R: other than Y rare earth elements) oxides have been recently introduced as promising oxygen storage materials that can be utilized in the temperature swing processes for the oxygen separation and air enrichment. In the present work, the average and local structures of Tb- and Ce-substituted Y0.7Tb0.15Ce0.15MnO3+δ and Y0.6Tb0.2Ce0.2MnO3+δ materials were studied, and their oxygen storage-related properties have been evaluated. The fully oxidized samples show the presence of a significant amount of the highly oxygen-loaded the so-called Hex3 phase, attaining an average oxygen content of δ ≈ 0.41 for both compositions. Extensive studies of the temperature swing process conducted in air and N2 over the temperature range of 180–360 °C revealed large and reversible oxygen content changes taking place with only a small temperature differences and the high dependence on the oxygen partial pressure. Significant for practical performance, the highest reported for this class of compounds, oxygen storage capacity of 1900 μmol O g−1 in air was obtained for the optimized materials and swing process. In the combined temperature–oxygen partial pressure swing process, the oxygen storage capacity of 1200 μmol O g−1 was achieved.

Highlights

In recent years, oxygen production has grown in importance because of the increasing demand from the industry and the health sectors
The oxygen contents derived from the X-ray diffraction (XRD) data are in good agreement with those obtained from the thermogravimetric measurements presented below
It should be mentioned that the synthesis of singlephase Y0.6Tb0.4-xCexMnO3 was successful up to x = 0.2 for samples fired at higher temperatures of 1400 °C

Summary

Introduction

Oxygen production has grown in importance because of the increasing demand from the industry and the health sectors. The driving force for the oxygen incorporation/release requires changes in the oxygen partial pressure of several orders of magnitude [8] This process is different from the surface-related pressure swing absorption, which is commercially used in systems that operate with the active material utilizing its surface selectivity for air constituents [9,10,11]. The OSMs of PSA type have been widely known since the early 1980s when the CeO2based materials were firstly implemented in the three-way catalytic converters used in the exhaust system of gasoline-fueled vehicles [12, 13] These OSMs work effectively as supporting catalysts to maintain the oxygen partial pressure in the exhaust gas at the desired level. While the usage of inert gas for reduction is possible in many cases, the slow kinetics of the process limits the practical application [22]

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Conclusion