Composite Pd and Pd Alloy Porous Stainless Steel Membranes for Hydrogen Production and Process Intensification

Abstract

The synthesis of composite Pd membranes has been modified by the addition of a Al(OH) 3 graded layer and sequential annealing at high temperatures to obtain membranes with high permeance and outstanding selectivity stability for over 4000 hours at 450°C. Most of the membranes achieved in this work showed H 2 flux well above 2010 DOE targets and in some case, also above 2015 DOE targets. Similar composite membranes were tested in water gas shift reaction atmospheres and showed to be stable with high CO conversion and high hydrogen recovery for over 1000 hours. The H 2 permeance of composite Pd-Au membranes was studied as well as its resistance in H 2 S containing atmospheres. H 2 S poisoning of Pd-based membranes was reduced by the addition of Au and the loss undergone by membranes was found to be almost totally recoverable with 10-30 wt%Au. PSA technique was studied to test the possibility of H 2 S and COS removal from feed stream with limited success since the removal of H 2 S also led to the removal of a large fraction of the CO 2. The economics of a WGS bundle reactor, using the information of the membranes fabricated under this project and integrated into an IGCC plant were studied based on a 2D reactor modeling. The calculations showed that without a government incentive to impose a CO 2 tax, application of WGS membrane reactors in IGCC would be not as economically attractive as regular pulverized coal plants.