The stability of composite palladium membranes is of key importance for their application in hydrogen energy systems. Most of these membranes are prepared by electroless plating

and beforehand the substrate surface is activated by a SnCl

2

-PdCl

2

process

but this process leads to a residue of Sn

which has been reported to be harmful to the membrane stability. In this work

the Pd/Al

2

O

3

membranes were prepared by electroless plating after the SnCl

2

-PdCl

2

process. The amount of Sn residue was adjusted by the SnCl

2

concentration

activation times and additional Sn(OH)

2

coating. The surface morphology

cross-sectional structure and elemental composition were analyzed by scanning electron microscopy (SEM)

metallography and energy dispersive spectroscopy (EDS)

respectively. Hydrogen permeation stability of the prepared palladium membranes were tested

at 450-600℃ for 400 h. It was found that the higher SnCl

2

concentration and activation times enlarged the Sn residue amount and led to a lower initial selectivity but a better membrane stability. Moreover

the additional Sn(OH)

2

coating on the Al

2

O

3

substrate surface also greatly improved the membrane selectivity and stability. Therefore

it can be concluded that the Sn residue from the SnCl

2

-PdCl

2

process cannot be a main factor for the stability of the composite palladium membranes at high temperatures.