(696a) Fabrication of Robust Pd-Ag and Pd-Cu Membranes On Microporous Stainless Steel Support by a Novel Electroless Plating Process

Dense Pd, Pd-Ag and Pd-Cu composite membranes on miceroporous stainless steel substrate (MPSS) were fabricated by novel electroless plating (EP) process [1]. In conventional Pd-EP process, the oxidation-reduction reactions between Pd-complex and hydrazine result in evolution of NH3 and N2 gas bubbles. When adhered to the substrate surface and in the pores, these gas bubbles hinder uniform Pd-film deposition which results in dendrite growth leading to poor film formation. We addressed this problem by introducing cationic surfactant in the electroless plating process what we call surfactant induced electroless plating (SIEP). The unique features of this innovation provides: (1) control of Pd-deposition rate, and (2) control Pd-grain size distribution. The surfactant molecules play an important role in the plating process in tailoring grain size and the process of agglomeration by removing tiny gas bubbles through adsorption at the gas-liquid interface. The water soluble surfactants which have almost neutral hydrophilic-lipophilic balance (HLB) value are believed to have stronger capability of removing gas bubbles from the substrate surface and the pores. The pre- and post-annealing characterizations of these membranes (Pd, Pd-Ag, and Pd-Cu on MPSS substrate) were carried out by SEM, XRD, EDX, and AFM analysis. SEM images showed significant improvement of the membrane surface morphology, in terms of metal grain structures compared to the membranes fabricated by conventional EP process. From x-sectional SEM and EDX study, we confirmed alloying of Pd-Ag and Pd-Cu at the annealing condition of about 500 C with different annealing time in hydrogen environment. These membranes were also studied for hydrogen perm-selectivity as a function of temperature and feed pressure. Some of these results will be discussed in this presentation.

1. Ilias, S., and Islam, M.A., "Methods for Preparing Thin Films by Electroless Plating." US Patent Application #20100068391, March 18, 2010.