Ultra-stable Ni-overdoped yttria-stabilized zirconia oxygen separation membranes for methane partial oxidation

Ceramic oxygen separation membranes have advantages over cryogenic distillation and pressure swing adsorption in terms of oxygen production. However, the application of ceramic membranes is restricted by membrane stability issues at high operation temperatures. This study develops ultra-stable oxygen separation membranes through the over-doping of Ni into yttrium-doped zirconia (NYSZ). The Ni doping amount reaches 18.1 mol%, and Ni dissolution substantially increases the electronic conductivity of the yttrium-doped zirconia membranes under both oxidizing and reducing atmospheres, which is as high as 0.96 S cm -1 . Accordingly, high oxygen permeation rates of up to 1.68 mL min -1 cm -2 at 800 °C were achieved, which are comparable with those of conventional perovskite membranes (3.53 mL min -1 cm -2 ). The ultra-stable NYSZ membranes were confirmed with stable electrochemical reforming of methane for 310 h. Therefore, the robust NYSZ membranes demonstrate great potential in practical applications.