Preparation And Performance Investigation Of Novel Perovskite-type Oxygen Adsorbents

This thesis aims to synthesize some new mixed-conductingperovskite-type oxides with superior performance to use as noveloxygen absorbents for temperature swing adsorption （TSA）oxygen–producing process. Based on series of mixed-conductingperovskite-type oxides BaxSr1-xCoyFe1-yO3-, the composition ratio ofmetal elements in the composite oxides was re-adjusted, and the B-siteof the perovskite structure was doped with different metal ionsincluding some common cation receptors of low chemical valence statesuch as Al3+and Co3+as well as some some cation receptors of highvalence state just like Ti4+and Nb5+. The Ba0.15Sr0.85M0.15Fe0.85O3-（M=Fe，Al，Co，Ti，Nb）composite metal oxides were synthesized by thesolid-state reaction method.In this thesis, we focused on the stability and oxygen adsorptionproperties of the novel oxygen absorbent Ba0.15Sr0.85M0.15Fe0.85O3-（M=Al，Co，Ti）oxides. Structure stability of the oxide materials werestudied at high temperatures，and the oxygen sorption capacity and theelectrical conductivity of the Ba0.15Sr0.85M0.15Fe0.85O3-（M=Fe，Al，Co，Ti）oxides were also investigated. XRD and high-temperature XRDcharacterizations indicate that the as-synthesized oxides can keep acubic single perovskite-type structure within a wide temperature rangeup to1000℃, and still keep a single perovskite structure afterlong-term calcination at800℃for100h, which means that theBa0.15Sr0.85M0.15Fe0.85O3-（M=Al，Co，Ti）oxides possess highstructural stability. In addition, the TG results shows that the Ba0.15Sr0.85M0.15Fe0.85O3-（M=Fe，Al，Co，Ti）oxides possess excellentcapability of the oxygen absorption and desorption. As the operatingtemperature was raised and lowered regularly between300℃~925℃, the mass of the Ba0.15Sr0.85M0.15Fe0.85O3-（M=Fe， Al， Co，Ti）oxides changed correspondingly. The mass percentage changes forthe Ba0.15Sr0.85M0.15Fe0.85O3-（M=Fe，Al，Co，Ti）oxides are2.70%,2.60%,2.80%and2.45%, respectively. According to the percentages ofmass changes, the oxygen sorption capacities of theBa0.15Sr0.85M0.15Fe0.85O3-（M=Fe，Al，Co，Ti）oxides are calculatedto be18.9mL(STP) g1,18.2,19.6,17.1oxide, respectively. Since the Ba0.15Sr0.85M0.15Fe0.85O3-（M=Al，Co，Ti）oxides exhibit good oxygen sorption/desorption propertiesat high temperatures, they may act as promising oxygen absorbents forthe TSA oxygen–producing process. Furthermore, theBa0.15Sr0.85M0.15Fe0.85O3-（M=Al，Co，Ti）oxides possess good sinteringand electrical conductivity properties, they may be helpful for theseperovskite-type oxides to be further applied to the R&D of themixed-conducting oxygen semi-permeable membranes and cathodematerials of solid oxide fuel cells.