کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
40562 | 45858 | 2013 | 9 صفحه PDF | دانلود رایگان |
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 α,β-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 Pd-EPS 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”).
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► Pd-EPS was prepared by Klebsiella oxytoca fermentation in the presence of Pd(NO3)2.
► Activated Pd-EPS was obtained by hydrogen treatment of Pd-EPS.
► Both palladium catalysts were active only in the presence of water.
► Both catalysts were easily recovered and reused in recycling experiments.
Journal: Applied Catalysis A: General - Volume 451, 31 January 2013, Pages 144–152