Resumo

ERASMUS, Elizabeth. Hydrogenation of cinnamaldehyde over an ionic cobalt promoted alumina-supported palladium catalyst. S.Afr.j.chem. (Online) [online]. 2013, vol.66, pp.00-00. ISSN 1996-840X.

Nano γ-alumina-supported transition metal-based mono- (Pd⁰/γ-Al₂O₃ or Co^III/γ-Al₂O₃) and bimetallic catalysts (Pd⁰Co^III/γ-Al₂O₃), were prepared by wet impregnation, oxidation and in situ reduction of the palladium. The palladium(II) acetate [Pd^II₃(OOCCH₃)₆], cobalt(II) acetate [Co^II(OOCCH₃)₂]^.4H₂O and palladium, cobalt bridging tetraacetate [Pd^IICo^II(OOCCH₃)₄]^.H₂O^.2CH₃COOH, were used as catalyst precursors to prepare a 7.4 % mol catalyst/support loading. The oxidation states of these activated catalysts were studied by XPS. These catalysts were evaluated for hydrogenation of cinnamaldehyde in a biphasic reaction under 3 MPa of hydrogen at 80 °C. The Pd⁰/γ-Al₂O₃ selectively catalyzed the hydrogenation of C=C bond in cinnamaldehyde to form phenylpropanol (100 %). In contrast, catalysis with Pd⁰Co^III/γ-Al₂O₃ hydrogenated both C=C and C=O bonds consecutively, forming 65 % phenylpropanal and 35 % phenylpropanol with TOF = 47.2 h^-1. No reaction occurred when Co^III/γ-Al₂O₃ was used.

Palavras-chave : Bimetallic heterogeneous catalyst; palladium; cobalt; hydrogenation; unsaturated aldehydes.

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