Cycling Performance and Hydriding Kinetics of LaNi5 and LaNi4.73Sn0.27 Alloys in the Presence of CO

G. O. MEYER; E.M. BORZONE; M.V. BLANCO; A. BARUJ

Rio de Janeiro

Conferencia; International Conference on Hydrogen Storage, Embrittlement and Applications (Hy-SEA 2014); 2014

U.F. Rio de Janeiro

Two AB5 alloys, LaNi5 and LaNi4.73Sn0.27, were cycled in H2 gas containing 10 and 100 ppm of CO to evaluate their potential for hydrogen purification applications. No significant loss of capacity was observed when samples were given enough time to complete the reaction, in contrast with works availabe in the literature that report a strong poisoning effect. Instead, the reaction kinetics was progressively retarded during the first few cycles and then it reached a stationary, repeteable condition. No further degradation was observed after this point. The results also suggest that a fraction of the adsorbed CO is released during the desorption process. Differences between present and previous results are discussed in terms of the experimental conditions. The effect of temperature was studied for the Sn-containing alloy. The main results indicate that at 90ºC the reaction is only slightly retarded by the presence of 10 ppm of CO, showing a half-time of less than a minute. At 40ºC, on the other hand, the retarding factor in the presence of 100 ppm of CO with respect to the kinetics in pure hydrogen is of about 600. The reaction is more retarded with increasing CO concentration and decreasing temperature. Results of these alloys? cycling performance in pure H2 are included for comparison.