Journal of Materials Science, Vol.46, No.13, 4690-4694, 2011
Proton conduction in BaxCe0.8Y0.2O3-alpha+0.04ZnO at intermediate temperatures and its application in ammonia synthesis at atmospheric pressure
Dense ceramic samples Ba (x) Ce0.8Y0.2O3-alpha + 0.04ZnO (x = 1, 0.98, 0.96, 0.94) were successfully prepared by a solid-state reaction method, whose sintering temperature was about 573 K lower than a traditional solid state reaction method without sintering aid. XRD patterns indicated that all the samples exhibited a single-phase of orthorhombic perovskite structure. The conduction behavior was investigated by alternating current impedance in wet hydrogen atmosphere at 673-1073 K. It was found that the conductivities were affected by the nonstoichiometric amount of Ba, and increased in the order: sigma (x = 0.94) < sigma (x = 1) < sigma (x = 0.96) < sigma (x = 0.98). It was also found that the samples were almost pure ionic conductors and contributed mainly by proton and partially by oxide ion in wet hydrogen atmosphere at 773-1073 K. The ammonia synthesis at atmospheric pressure was successfully conducted using an electrolytic cell based on Ba0.98Ce0.8Y0.2O3-alpha + 0.04ZnO. The ammonia formation rate reached 2.36 x 10(-9) mol s(-1) cm(-2) under the suitable conditions of 0.8 mA and 773 K.