Tubular zirconia–yttria electrolyte membrane technology for oxygen separation

Azeotropic distillation, ethanol washing, and freeze drying on coprecipitated gels for production of high surface area 3Y–TZP and 8YSZ powders: A comparative study

“…When 8 mol% Y 2 O 3 is alloyed in the zirconia-rich portion of the ZrO 2 -Y 2 O 3 system, fully-stabilized zirconia (8YSZ) is formed [1]. Because of its large concentration of oxygen vacancies, 8YSZ is currently the electrolyte material of choice in solid oxide fuel cells [2], and is also applied in membrane technology for oxygen separation [3], and in gas sensors [4,5]. Alternatively, addition of 3 mol% Y 2 O 3 produces stabilized tetragonal zirconia polycrystals (3Y-TZP) [1,6].…”

Atomic-Scale Observation of Migration and Coalescence of Au Nanoclusters on YSZ Surface by Aberration-Corrected STEM

“…Here, we apply aberration-corrected scanning TEM (STEM) to directly observe surface migration, coalescence, and atomic rearrangement of Au clusters on an Y:ZrO 2 (YSZ) (100) support at the atomic scale. The heterogeneous Au/YSZ system is chosen because it finds a plethora of applications as gas sensors 16 17 , gas pumps 18 , solid oxide fuel cells 19 20 , and electrochemical reactors 21 . We offer definitive evidence that the Au/YSZ heterointerface can be initially epitaxial and coherent, and demonstrate that it undergoes structural rearrangement by migration and coalescence, which finally induces transformation of Au particles and also breaks coherency of the heterointerface.…”

Oxygen removal and level control with zirconia — Yttria membrane cells

“…The temperature of the gas exiting the device is not a serious problem as it can be brought to room temperature even for flow rates as high as 3-4 litres/mirdtube with an inexpensive heat exchanger. Single tube devices have been operated previously in the oxygen generation mode for periods exceeding 7000 h and showed very low degradation [4].…”

“…The tubular design inherently requires minimal sealing and is also subjected to low thermal stresses during its use. The starting materials for the manufacture of the ceramic membrane were commercial grades of 3 tool% Y203 -ZrOa powders which were pressed into tube shapes using a dry bag isostatic press [4]. The green tubes were stacked and fired at 1400 or 1500 ~ for 4 hours in air.…”

“…In a previous publication, operation of the device for oxygen generation has been described [4]. In this paper, operation and limitations of laboratory scale prototypes constructed from tubular zirconia -yttria membranes have been described for continuous oxygen removal and generation of calibration gases with known levels of oxygen.…”