Tailoring of new amorphous alloy catalysts for conservation of atmosphere

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Since non-equilibrium alloys become a single phase supersaturated solid solution by additions of large amounts of various elements, tailoring of catalysts for conservation of environments by combination of elements necessary for high reactivity and selectivity was aimed.1. Catalysts for decomposition of nitrogen oxides : For direct decomposition of nitrogen oxide to nitrogen and oxygen, Pd/NiTaO_6 catalyst formed from amorphous Ni-Ta-Pd alloys showed the most stable high reactivity in a wide temperature range up to 900ﾟC.When this was used as a catalyst for reduction of nitrogen monoxide by propane in oxygen containing atmosphere, a high conversion was observed at low temperatures such as 300ﾟC2. Catalysts for decomposition of chlorofluorocarbon : Amorphous Ni-Zr alloys possess high reactivity and durability for hydrolytic decomposition of CFC-12 into CO_2, HC1 and HF.The durability increased remarkably by the addition of phosphorus. Active species formed from the alloys were ZrF2, (F,O)_<2,706> and Zr(F,O)_<3.80ﾟ>3. Catalysts for methanation of carbon dioxide : Amorphous Ni-Zr alloys have the highest activity and 100% selectivity for methane formation by the reaction of CO_2 with H_2 in comparison with conventional Ni-impregnated ZrO_2, crystalline Ni-Zr and precious metal catalysts. Because nickel supported on tetragonal ZrO_2, which is an essentially metastable phase and formed during the reaction, showed a selectively high activity and because the addition of rare earth elements stabilizes the tetragonal ZrO_2 phase, the most active catalysts were obtained from amorphous Ni-Zr-rare earth element alloys.4. Hydrogen evolution cathodes for seawater electrolysis : Tailoring of highly active electrodes for production of hydrogen necessary for methanation of CO_2 was carried out by preparing amorphous alloys. Modification of the electronic structure of nickel by the addition of molybdenum resulted in the cathodes whose activities are competitive to that of platinum.