Aqueous biphasic hydrogenations catalyzed by new biogenerated Pd-polysaccharide species

Authors: Stefano Paganelli, Oreste Piccolo, Franco Baldi, Riccardo Tassini, Michele Gallo, Giorgio La Sorella

Abstract:
A palladium species bound to an exopolysaccharide (Pd-EPS) was obtained from alive bacterial cells of Klebsiella oxytoca BAS-10 grown in static mode in the presence of Pd(NO₃)₂. Pd-EPS, after isolation and purification, was used as catalyst in the aqueous biphasic hydrogenation either of unfunctionalyzed olefins, as styrene, 1-octene and 1,3-diisopropenylbenzene, or of some ,-unsaturated aldehydes. The catalytic system was very active under mild reaction conditions and its activity was maintained in some recycle experiments. Even more efficient was the “activated Pd-EPS”, obtained by a pre-treatment of PdEPS with 1 MPa of H2 at 30 ^◦C for 21 h; while Pd-EPS originally contains only Pd(II), as demonstrated by XPS measurements, the activated catalyst shows the presence of both Pd(II) and Pd(0) in the ratio 1.9/1. The two catalytic systems show different structures at TEM observations evidencing the transformation of electron ultradense nanoaggregates (Pd-EPS) into jagged microaggregates (“activated Pd-EPS”).

Keywords:
Palladium
Biphasic hydrogenation
Catalyst
Klebsiella oxytoca
Polysaccharide

Published in: Applied catalysis A: General  (Volume 451, Pages 1-288, 31 January 2013)

Publisher: Elsevier

ISSN Information: 0926-860X

Aqueous biphasic hydrogenations catalyzed by new biogenerated Pd-polysaccharide species

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