Direct methane oxidation over a Bi2O3–GDC system

A novel ceramic system was prepared by adding Bi2O3 to gadolinia-doped ceria (GDC). This Bi2O3–GDC system was characterized by temperature-programmed and fixed-temperature reaction of methane in the absence of gas-phase oxygen. It was found that adding Bi2O3 to GDC can promote the catalytic activity for direct methane oxidation. A Bi2O3 loading of 25 wt% in the Bi2O3–GDC system maximized the activity of direct methane oxidation. Possible carbon deposition after the reaction can be negligible. In the temperature range of an intermediate-temperature solid oxide fuel cell (SOFC), pre-reduction promotes methane oxidation activity. At temperatures of about 600 °C or lower, only CO2 and H2O are produced. However, CO and H2 can be produced only at a temperature of about 700 °C or higher. This Bi2O3–GDC system can be applied to design SOFC anode materials for complete methane oxidation and thus full electricity generation, without syngas cogeneration, at low temperature.