Surface properties of binary and ternary alloys under the presence of CO, CO2 and H2S.

A. DALLA FONTANA, L. M. CORNAGLIA, AND A. M. TARDITI.

SANTA FE

Conferencia; VI San Luis Conference on Surfaces, Interfaces and Catalysi; 2018

Pd-based membranes are the most promising technology to be employed in hydrogen purification processes, due to their high permeability and infinite selectivity. The permeation mechanism through Pd films is the solution-diffusion which Vconsists of the following stages: (i) molecular hydrogen adsorption on the surface, (ii) molecular dissociation, (iii) atomic diffusion through the alloy, (iv) recombination and (v) desorption of H2 from the permeate side. Although their excellent properties, Pd and most of its alloys are very sensitive to sulfur compounds even at low ppm levels1,2. Along with H2S, CO is another important contaminant normally present when generating H2 from fossil fuels. For this reason, different binary and ternary Pd-based alloys have been studied. The study of surface properties of the membranes exposed to operation conditions, is a necessary step for a better understanding of the phenomena involved in the hydrogen permeation and for the optimization of their performance. With the aim to analyze the effect of CO, CO2 and H2S on the surface properties of PdAu and PdAgAu alloys, XPS and LEIS experiments were performed after exposure to different treatments: i) H2/Ar, ii) CO/He, iii) CO2/Ar and iv) after exposure to H2S(100 ppm)/H2.