Palladium and palladium alloy composite membranes prepared by metal-organic chemical vapor deposition method (cold-wall)

Thin Pd and Pd–Ni alloy membranes were prepared by the MOCVD method using an cold-wall technique. Pd(C3H5)(C5H5) and Ni(C3H5)(C5H5) were decomposed into densely aggregated metal crystallites that were to plug mesoporous nickel-stainless steel (Ni-SUS) or γ-Al2O3/α-Al2O3 supports. The use of highly volatile organometallic precursors enabled continuous and controlled deposition mode, which resulted in reproducible formation of thin impervious Pd or Pd–Ni alloy membranes. Pd(C3H5)(C5H5) and Nb(C3H5)(C5H5)5 were deposited in a layer by layer deposition method. The H2 permeance of the Pd/Ni-SUS membrane was 2.0–5.0×10−2 cm3 cm−2 cmHg−1 s−1 (723 K); the H2/N2 selectivity was 1600. The H2 permeance of the Pd/Al2O3 was 1.5×10−2 cm3 cm−2 cmHg−1 s−1 (723 K); the H2/N2 selectivity was >1000.