EFFECT OF PRETREATMENT CONDITION ON HYDROGENATION ACTIVITY OF AMORPHOUS NI-CE-P ALLOY

Amorphous Ni82.0Ce0.31P17.7 and Ni82P18 alloys in the form of ca. 5 mm wide and 10-20-mu-m thick ribbon were prepared by vacumm rapid quenching method. DSC results indicated that amorphous Ni-P alloy start to crystallized at 360-degrees-C. With the addition a small amount of Ce to Ni-P amorphous alloy, its crystallizing temperature increased to 520-degrees-C. Liquid-phase hydrogenation of styrene was selected as probe reaction to study the effect of pretreatment condition on the catalytic activities of the amorphous alloy. Their hydrogenation activities increased after pretreated with O2 and H-2, and the best pretreatment condition was to oxidize the amorphous alloy at 240-degrees-C for 1h, and then to reduce at 300-degrees-C for 2h. Catalytic activity of Ni-Ce-P amorphous alloy was found to be 3-4 times active as Ni-P amorphous alloy, and catalytic activites of both Ni-P and Ni-Ce-P decreased after crystallization. AES and XPS results showed that the pretreatment with O2 and H-2 not only increased the concentration of Ni, but also changed the electronic state of Ni on the Ni-Ce-P surface.