The effect of Fe/Co ratio on the structure and oxygen permeability of Ca-containing composite membranes

Abstract

Ceramic composite oxygen transport membranes 60 wt%Ce_0.9Pr_0.1O_2−δ–40 wt%Pr_0.6Ca_0.4Fe_1−xCo_xO_3−δ (0 ≤ x ≤ 1) were synthesized via the Pechini one-pot method. X-ray diffraction patterns indicated that membranes of all compositions maintained the same crystal structure at the room temperature, whereas with the decrease in the Fe/Co ratio, it was more easier to find phase decomposition under Ar environment at an elevated temperature. SEM images demonstrate that the mechanical compatibility of the two phases becomes worse and the grain size gradually increases with the increase in the Co content. Oxygen permeability test results showed that the reduction in the Fe/Co ratio improved the oxygen permeability of the membrane for x ≤ 0.6, while the reduction in the Fe/Co ratio had an adverse impact on the oxygen permeability for x ≥ 0.8. Among all the composition membranes, 60 wt%Ce_0.9Pr_0.1O_2−δ–40 wt%Pr_0.6Ca_0.4Fe_0.4Co_0.6O_3−δ membrane possessed the highest permeation flux of about 0.85 mL min⁻¹ cm⁻² at 1000 °C under air/He atmosphere. The final stability testing indicated that it possessed good stability under air/He, and thereby has potential application prospects in high temperature oxygen consumption industries.