An Intermediate-Temperature Oxygen Transport Membrane Based on Rare-Earth Doped Bismuth Oxide Dy_0.08W_0.04Bi_0.88O_2-δ

Abstract

In this work, a ceramic oxygen pump based on dysprosium and tungsten co-doped bismuth oxide (DWSB) was synthesized and characterized. The DWSB oxygen ion conducting electrolyte with a composition of Dy 0.08 W 0.04 Bi 0.88 O 2-δ displayed the highest oxygen ion conductivity and was chemically compatible with the La 0.8 Sr 0.2 MnO 3-δ (LSM) electrode material. A composite electrode was fabricated with DWSB-LSM in the mass fraction of 50:50 exhibiting the lowest polarization resistance with the DWSB electrolyte. In the composite electrode, larger DWSB particles act as backbone for the oxygen transport pathway, while LSM particles deposited on the surface of the DWSB backbone serve as mixed ionic-electronic conductors accelerating surface oxygen exchange. An oxygen flux of 5.9 mL cm −2 min −1 at 650 • C under 1 V applied bias was realized in the DWSB electrolyte (0.75 mm) supported membrane incorporating DWSB-LSM electrodes on feed and permeate sides. Further improvements to the electrochemical performance were achieved by fabricating a thin, electrode supported DWSB membrane (∼12 µm). The current density for the electrode-supported cell was 5.4 Acm −2 under 2 V applied bias at 650 • C which corresponds to an oxygen flux of 17 mL cm −2 min −1. Higher bias voltages were observed to accelerate the electrode reaction process leading to reduced polarization resistance that resulted in a remarkable growth of current density. This intelligent DWSB based oxygen pump is a promising materials system for high performance electrochemical oxygen separation.

A high performance IT-EOG cell based on a solid/molten Bi2O3–B2O3 composite electrolyte

“…In majority of IT-EOGs, the samaria-doped ceria Ce 0.8 Sm 0.2 O 2Àd (SDC), ittria-stabilized bismuth oxide Bi 1.46 Y 0.54 O 3 (YSB), erbia-stabilized bismuth oxide Bi 1.6 Er 0.4 O 3 (ESB), dysprosium-and tungsten-stabilized bismuth oxide Dy 0.08 W 0.04-Bi 0.88 O 1.56 (DWSB), and bilayer SDC/ESB ceramic electrolytes are used. [7][8][9][10][11][12][13] However, the ionic conductivity of these ceramic electrolytes is lower than that of the newly developed solid/ molten Bi 2 O 3 -0.2 wt% B 2 O 3 composite electrolyte (Fig. 1b).…”

Oxygen pumping based on <i>c</i>-axis-oriented lanthanum silicate ceramics: challenge toward low operating temperature

“…11)13) Among them, Hong et al recently reported an excellent oxygen pumping system based on the Dy 0.08 W 0.04 Bi 0.88 O 2¹¤ (DWBO) electrolyte, which shows a high oxide ionic conductivity of 0.13 S cm ¹1 at 650°C, with a La 0.6 Sr 0.4 MnO 3¹¤ /DWBO composite electrode, and demonstrated a high oxygen flux of 2.4 mL cm ¹2 min ¹1 under a DC of 1.0 V at 600°C. 13) This result strongly indicates that the high oxide ionic conductivity of the electrolyte plays an important role in design of a low-power consumption oxygen separation system. Hence, the use of a material whose oxide ionic conductivity exceeds that of DWBO can lead to a further reduction in the operation temperature.…”

Solid Oxide Electrochemical Cells for Nitrogen and Oxygen Production

“…One of the important applications is producing N 2 for electrified or retrofitted Haber-Bosch ammonia production plant using green hydrogen produced from water electrolysis. Electrochemical oxygen pumping using cells with oxygen ion conductor such as rareearth doped bismuth oxide Dy 0.08 W 0.04 Bi 0.88 O 2-δ and yttria doped zirconia (YSZ) have been reported for producing high pure oxygen from air (1)(2)(3)(4), with excess air supplied from the cathode compartment. Such a concept has been further developed for N 2 production with controlling the cathode feeding air and oxygen extraction rate for pure oxygen production at the anode compartment and N 2 production at the cathode compartment (5).…”