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Synthesis and characterization of Pd membranes on alumina modified porous stainless steel supports

pubblicazioni - Articolo

Synthesis and characterization of Pd membranes on alumina modified porous stainless steel supports

Palladium composite membranes have been obtained by deposition of Pd on alumina modified stainless steel supports. The preparation procedure involves deposition of a double layer of γ-alumina (γ-Al 2 O 3 ) on the support by dip coating followed by drying and calcination, activation of the modified support, deposition of palladium by electroless plating.

SEM/EDS and Auger spectroscopy analysis coupled with sputtering allowed the identification of critical issues and a proper re-elaboration of the preparation procedure. It has been found that γ-Al 2 O 3 completely covers the support surface determining a strong reduction of the surface rugosity. Activation, however, even if performed inside the γ-Al 2 O 3 pH stability range, determines the partial dissolution of alumina; this phenomenon is enhanced while decreasing pH value. Moreover, Pd seeds, which catalyze subsequent Pd deposition, are not well distributed on the surface. As a consequence of the above observations, membrane preparation has been modified by introducing a pre-activation of the γ-Al 2 O 3 external layer consisting in the addition of palladium chloride to the alumina gel and palladium reduction in sodium boron hydride solution after calcination.

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