Thermal decomposition of ammonia over nickel/gadolinium-doped ceria cermet

Abstract

A biogas, which contains 60% of methane, 40% of carbon dioxide and a small amount of hydrogen sulfide and ammonia, is a possible fuel of solid oxide fuel cell. Thermal decomposition of 1000 ppm NH3 in Ar gas was measured over Ni (30 vol%)/ Ce0.8Gd0.2O1.9 (GDC) electrode attached to dense GDC electrolyte at 673-1073 K. Pyrolysis of NH 3 started above 773 K and reached 94% at 1073 K. Although N 2 gas was detected in the exhaust gas, H2 gas was not measured. Furthermore, the oxygen partial pressure of the outlet gas was high. These results are discussed with the properties of GDC mixed conductor (oxide ions and electrons). © 2008 The Ceramic Society of Japan. All rights reserved.