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CVD synthesis and gas permeation properties of thin palladium/alumina membranes
Author(s) -
Xomeritakis George,
Lin YueSheng
Publication year - 1998
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690440118
Subject(s) - permeance , palladium , membrane , permeation , chemical engineering , metal , materials science , knudsen diffusion , diffusion , chemical vapor deposition , mesoporous material , inorganic chemistry , chemistry , polymer chemistry , metallurgy , nanotechnology , organic chemistry , catalysis , biochemistry , physics , engineering , thermodynamics
Thin (0.5–5‐ μm) palladium (Pd) membranes were prepared inside pores or on the suface of mesoporous (pore size 4–6 nm), sol – gel‐derived γ‐Al 2 O 3 supports by the chemical vapor deposition (CVD) method using palladium acetylacetonate and palladium chloride (together with hydrogen) as Pd precursors. When Pd is deposited in the form of metal plugs inside pores of γ‐Al 2 O 3 , He permeance of the composite membranes increases exponentially with temperature, indicating activated diffusion through the rnicroporous metal deposit defects, while only modest permselectivity for H 2 is observed. When Pd is deposited in the form of a metal film on the surface of γ‐Al 2 O 3 , He permeance is governed by Knudsen‐viscous flow through meso/macroporous metal film defects. The H 2 permeance of different palladium membranes prepared by CVD appears to increase with palladium crystal grain size. The highest H 2 permeance and H 2 :He permselectivity for membranes prepared in this study are about 1.0–2.0 × 10 −7 mol·m −2 ·s −1 ·Pa −1 and 200–300 at 300°C, respectively.