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.