Novel carbon-based Ni/Fe catalysts derived from peat for hot gas ammonia decomposition in an inert helium atmosphere

Two novel carbon-based Ni/Fe catalysts were developed and tested for catalytic decomposition of ammonia into N-2 and H-2. These catalysts were prepared using a mesoporous activated carbon (AC) support derived from a Canadian peat by H3PO4 activation. The newly developed catalysts proved to be highly active for ammonia decomposition. The conversion of 2000 ppm NH3 diluted in helium over the Fe catalyst reached as high as 90% at 750 degrees C and at the space velocity of 45,000 h(-1), compared with only about 15% with the activated carbon alone without metal loading. The new catalyst of Fe/AC was also much more active than the Fe catalyst supported on a commercial activated carbon reported previously. In addition, the new Fe/Ni catalysts showed superior performance with respect to their resistance to catalyst deactivation. Both catalysts remained active as the reaction time increased up to 10 h without showing a sign of deactivation. Fresh and spent catalysts were characterized by XRD and XPS. A cycle mechanism, involving both metal phosphides and metal nitrides, was proposed for the NH3 decomposition reactions over these new Fe/Ni catalysts. (C) 2009 Elsevier B.V. All rights reserved.