Analysis and improvement of chemical stability of Y-doped BaCeO3 as proton conducting electrolytes in C3H8-O-2 fuel cells

摘要

The stability of Y-doped BaCeO3 has been investigated as a proton-conducting electrolyte for use in fuel cells for propane dehydrogenation. Although this material was chemically stable in propane at high temperatures, a 120 h stability test showed that the conductivity of Y-doped BaCeO3 electrolyte varied over time. SEM and EDX analysis showed that the anode surface of the electrolyte membrane deteriorated when exposed to a low concentration of carbon oxides arising from oxidation of anode fuel by trace amounts of oxygen that diffused through the sealant, which became porous during sintering. The fuel cell set-tip was redesigned with suitable sealants, after which carbon oxides in the fuel cell were dramatically suppressed so that concentrations of carbon oxides were constricted to below 30 ppm under,fuel cell operating conditions (temperature: 600 - 700 degrees C and propane flow rate: 50- 200 ml/min). With the new set-ups, there was no obvious degradation of the conductivity of Y-doped BaCeO3 after 120 h, and SEM showed no changes on the surfice of electrolyte membrane. In addition through improving fuel cell set-up designs, fuel cell performance apparently increased by dramatically suppressing carbon monoxide that is a poison to the platinum catalyst.