THE EFFECT OF H2S ON THE LONG-TERM STABILITY OF Pd/Cu MEMBRANES AND THE CHARACTERISITICS OF H2S POISONING OF ELECTROLESS DEPOSITED Pd

Hydrogen selective Pd and Pd alloy membranes can improve the efficiency and cost effectiveness of the coal gasification process by recovering high purity H2 from the syngas. Also, the high pressure CO2 in the retentate reduces the cost of carbon capture required for carbon sequestration. However, small quantities of H2S present in the gas stream poison the Pd membranes and reduce the hydrogen permeance by either adsorbing on the surface or reducing the selectivity of the membrane by forming a sulfide scale. Pd/Cu membranes have been tested and shown to be more tolerant to H2S than pure Pd, but bulk analysis methods such as EDS (Energy Dispersive Spectroscopy) and XRD (X-ray Diffraction) were not sufficiently surface sensitive to detect the adsorbed sulfur on poisoned membrane surfaces. Therefore, the objective of this study was to examine the interactions of H2S with Pd that led to membrane poisoning with the more surface sensitive technique of XPS (X-Ray Photoelectron Spectroscopy), and to test the long-term stability of Pd/Cu membranes in the presence of H2S with the purpose of designing sulfur tolerant membranes.