A Study of the Preparation of Porous Amorphous Alloys and Their Catalysis

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In the series of study on catalysis by amorphous metal alloys, we found that the alloys revealed high turnover frequencies in hydrogenation and/or dehydrogenation reactions. However, the surface area of the alloy is small and the catalytic activity normalized to a unit mass is substantially lower than that of conventional catalysts.In the present study, the enlargement of surface area has been attempted by adopting a technique : doping and leaching of zinc or aluminum. Doping of additional metal is performed by two manners : 1) heating a mixture of zinc or aluminum powder and an amorphous alloy powder, 2) thermal decomposition of zinc formate adsorbed on the surface of alloy powder. The second method is found to be suitable for preparation of porous amorphous alloys with high surface area. For leaching process of the doped metals, a treatment of dilute NaOH solution is found to be suitable. Thus, porous amorphous alloys th surface area of 7-9 m^2 g^<-1> were obtained.These alloys revealed high catalytic activity in hydrogenation of butadiene or dehydrogenation of methanol to methyl formate. Detailed studies on dehydroqenation of methanol by porous Cu-Ti and Cu-Zr catalysts have been carried out to investigate the effects of pretreatments and reaction conditions on the activity and selectivity.