Grace : Development of Pd-zeolite composite membranes for hydrogen production by membrane reactor

•  Pd–zeolite composite membranes have been prepared over the external surface of macroporous a-alumna tubular supports by secondary growth of zeolite layers followed by Pd modification. Pd nanoparticles (few nanometers in size) filtration and/or impregnation þ in situ reduction of an organic Pd precursor have been explored as deposition techniques devoted to enhance the H2 separation performance of the non-defect free A-type zeolite membranes. The Pd deposition aims toward the partial blockage of the non-selective intercrystalline pathways, which may account for a significant fraction of the total permeation flux. The Pd–zeolite composite substrates have been characterized by XRD, SEM and EDX. The study of the permeation properties of these substrates for single (N2) and binary mixtures (H2–CO2) before and after Pd modification, reveals some improvements in terms of H2 separation performance. The impregnation þ in situ reduction of palladium acetylacetonate solution (Pd(acac)2) carried out over KA zeolite membranes previously seeded with Pd nanoparticles appears as the most adequate among the tested methods. Separation factors for H2-CO2 binary mixtures up to 145 have been achieved, although further optimization is required to improve the H2 permeation fluxes (around 1028 mol H2/m2 s Pa).

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering (hsv//eng)

Nyckelord

Chemical engineering

Kemiteknik

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