Developing a procedure to optimize electroless deposition of thin palladium layer on anodic alumina membranes

In recent years, the increased demand for hydrogen in many industrial applications, like petrochemical and semiconductor processing, and sustainable energy (fuel cells) has led to a renewed interest in methods for separation and purification of hydrogen from gas mixtures. In particular, palladium-based membranes have been the subject of many studies, due to their potential use as hydrogen-selective membranes for gas separation or purification [1,2]. Owing to the high cost of palladium and in order to increase the flow rate of hydrogen, composite membranes, formed by a thin layer of palladium deposited on a porous support, are largely preferred to thick self-standing metal membranes. Different supports were extensively used to prepare composite membranes resistant to the high temperature required for fast gas permeation through a dense palladium layer. A severe drawback in using composite membranes is due to the possible presence in the palladium layer of pinholes and/or cracks, which reduce the selectivity.