Synthesis, Oxygen Permeation, and CO2-Tolerance Properties of Ce_(0.8)Gd_(0.2)O_(2-δ)-Ba_(0.95)La_(0.05)Fe_(1-x)Nb_xO_(3-δ) Dual-Phase Membranes

摘要

A series of CO2-tolerant dual-phase dense oxygen permeable membranes of stoichiometry Ce_(0.8)Gd_(0.2)O_(2-δ)-Ba_(0.95)La_(0.05)Fe_(1-x)Nb_xO_(3-δ) (CG-BLF_(1-x)N_x, x = 0, 0.025, 0.05, 0.10, and 0.15) were designed and prepared by the sol-gel method. Their stability regarding phase composition and structure, oxygen permeability, and CO2-tolerant property were investigated by X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TG-DSC), and temperature-programmed desorption of oxygen (O2-TPD). Results of the materials characterization showed excellent chemical compatibility between CG and BLF_(1-x)N_x without the formation of any impurity phase after sintering at 1200 °C in air. The oxygen-permeation experiments showed that with increasing niobium content, the oxygen permeability of the CG-BLF_(1-x)N_x membranes decreased slightly, but the compositional and structural stability in CO2 atmosphere improved significantly. The 60 wt % CG-40 wt % BLF_(0.9)N_(0.1) membrane showed simultaneously good oxygen permeability and excellent CO2 tolerance, and the oxygen-permeation flux reached 0.195 mL·cm~(-2)·min~(-1) in pure CO2 atmosphere at 925 °C using a 1.0 mm thick membrane. This work demonstrates that CG-BLF_(1-x)N_x dual-phase membranes have great application potential for separating oxygen from highly concentrated CO2 atmosphere.