Nitric oxide reduction catalyzed by amorphous copper-zirconium and copper-titanium alloys

Amorphous alloys have been regarded as interesting from the catalytic point of view because they lack of long range ordering. Moreover, the surface of amorphous alloys is rich in low-coordination sites and defects which play no important role in catalysis. Amorphous Cu-Zr and Cu-Ti ribbons were prod uced by melt spinning methods, The surface of amorphous materials was prepa red. before catalytic tests, by immersion in HF solutions or by H-2 flow re duction. A selective dissolution of first transition metals was exhibited b y HF surface pre-treatment, A porous and Cu-rich surface was obtained, in t ile reduction of NOx with propylene ill presence of O-2, amorphous ribbon e xhibited an initial high activity that decreased until the steady-state was reached. This behaviour can be explained with the oxidation of copper acti ve sites by the oxygen contained in the reaction stream. Cu-Zr alloys showe d higher catalytic activity than Cu-Ti alloys. Moreover, the HF treatment i ncreased the activity of tile materials, and the HF treated alloys were mor e active than the lit treated alloys. (C) 2001 Elsevier Science B.V All rig hts reserved.