Effects of sulfur poisoning on hydrogen desorption from palladium

We present an analysis of the effect of sulfur poisoning on hydrogen desorption kinetics from palladium samples with different geometry and surface-to-volume ratios (fine powder, granules, foils and wires). The desorption process was studied by thermal desorption spectroscopy (TDS). The main effect of poisoning is a decrease of the desorption rate that shifts the TDS spectra towards higher temperatures in an amount that ranges from 30 to 80 K depending on the surface-to-volume ratio. The hydrogen storage capacity of the material remains unchanged after poisoning. The observed behavior could be well explained assuming a surface blocking effect produced by sulfur. (C) 2002 Elsevier Science BY All rights reserved.