Effect of HF pretreatment on H2 reactivity with LaNi5 and LaNi4.7Al0.3

Abstract The effect of fluorination of LaNi 5 and LaNi 4.7 Al 0.3 surfaces on the initial activation of hydrogen absorption was examined at 298 K by the measurement of H 2 reaction probability under ultra high vacuum and low vacua conditions, and by the measurement of the initial rate of hydrogen absorption at pressures over 10 6 Pa. The HF pretreated LaNi 4.7 Al 0.3 and LaNi 5 alloys degassed up to ultra high vacuum, and no improvement or even a marked reduction in the H 2 reaction rate was observed. However, the HF pretreated LaNi 4.7 Al 0.3 degassed at low vacuum exhibited a much higher reactivity than the sample degassed in ultra high vacuum. The results obtained show the importance of alumina present in the fluorination, and a possible enhancement of catalytic properties by the oxidation of fluorinated LaNi 4.7 Al 0.3 .