Application of sputter deposition technique to the preparation of amorphous alloy-derived catalysts for NO decomposition

Sputter deposition technique has been applied to the preparation of amorphous alloy precursors of catalysts on a fine oxide powder, in order to overcome the low surface area of the catalysts prepared from melt-spun amorphous alloy precursors. Amorphous Ni-Ta-Pd alloys have been sputter-deposited onto the γ-alumina powder with a high surface area, and then pre-oxidized at 1023 K in a 0.5% NO atmosphere. During the preoxidation, the amorphous alloys have been converted to palladium catalysts supported on the NiTa₂O₆ double oxide. The BET areas of the catalysts thus prepared (sputter-deposited catalysts) are approximately 50 times higher than those prepared from a melt-spun Ni-40Ta-1Pd alloy precursor (melt-spun catalyst). The catalytic activity of the sputter-deposited catalysts for NO decomposition becomes about twice as high as that of the melt-spun catalyst. Furthermore, the selectivity of nitrogen formation is also improved compared with the melt-spun catalyst. Accordingly, the application of sputtering technique is quite suited for preparing amorphous alloy catalyst precursors with a high surface area.