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Fe-Co alloy catalyst for NH3 decomposition to COx-free hydrogen
|Weiqing Zheng , Jian Zhang , Robert Schlögl , Dangsheng Su|
Fritz-Haber-Institute of Max-Planck-Gesellschaft, Faradayweg 4-6, Berlin D-14195, Germany
In order to reduce the pollution arising from automobiles exhausts, hydrogen has been extensively studied as the ultimate clean energy carrier to replace fossil fuel. Nowadays, ammonia decomposition to provide COx-free hydrogen has attracted renewed interest due to its oustanding advantages over the conventional routes based on carbonaceous materials. In this study, we studied the microstructure and catalytic performances of Fe-Co alloy nanoparticles, with different Fe/Co ratios, supported on commercial carbon nanotubes for ammonia decomposition. Elemental mapping of energy filtered transmission electron microscopy (EFTEM), electron energy-loss spectroscopy (EELS) and powder X-ray diffraction (XRD) results suggest an almost complete alloy state between Fe and Co in all bimetallic samples. Catalytic activity and stability tests of different catalysts were carried out with 36000 ml/(h gcat) NH3 space velocity at given temperatures. Results indicated that replacing Co by less active but much cheaper Fe was found to keep the high activity but greatly improve the stability. We attributed these improvements to the electron donation effect of Co to Fe, which could assist the N adatoms to desorb from surface with a low activation barrier.
Presentation: Poster at E-MRS Fall Meeting 2008, Symposium D, by Weiqing Zheng
See On-line Journal of E-MRS Fall Meeting 2008
Submitted: 2008-05-11 13:42 Revised: 2009-06-07 00:48