Effect of Zirconium Doping on Hydrogen Permeation through Strontium Cerate Membranes

SrCe0.95Tm0.05O3-delta perovskite-type ceramic membranes offer high hydrogen selectivity, thermal stability, mixed protonic-electronic conductivity, and mechanical strength at temperatures above 600 degrees C. However, in order for the SrCeO3-based membranes to be used in industrial applications, the chemical stability of the membranes in various environments must be improved. The effect of doping zirconium on the chemical stability, lattice Structure, protonic and electronic conductivity, and hydrogen permeation properties of SrCe0.95-xZrxTm0.05O3-delta (0 <= x <= 0.40) was studied. X-ray diffraction analysis verifies that all samples consist of a single perovskite phase. Doping zirconium in SrCe0.95Tm0.05O3-delta results in a decrease in both the protonic and electronic conductivity of the materials under reducing conditions, and a more significant decrease in hydrogen permeability of the membrane in CO2 free gas streams. In a CO2-containing environment SrCe0.75-xZr0.20-Tm0.05O3-delta membranes have a larger steady-state H-2 flux and superior chemical stability over SrCe0.95Tm0.05O3-delta membranes.