Silica supported Group VIII metal catalysts (Pd, Pt, Ru, Rh and Ir) have been tested at 303K in liquid phase reaction of cis-2-butene-1,4-diol with hydrogen at atmospheric pressure. The catalysts have been characterized by TPR, XRD and TEM. The catalytic activity changes in the order: PdRh > Pt > Ru > Ir. Significant differences were observed in products distribution. Ir/SiO2 and Pt/SiO2 favour the hydrogenation reaction to butane-1,4-diol, whereas Rh/SiO2, Pd/SiO2 and Ru/SiO2 significantly promote double bond and geometric isomerization processes, leading to 2-hydroxytetrahydrofuran and trans-2-butene-1,4-diol, respectively. Formation of products, deriving from isomerization and hydrogenation reactions, is explained on the basis of a mechanism involving a common -alkyl metal bonded intermediate and the variation in products distribution among the various metals is rationalized taking into account electronic factors.

Hydrogenation versus isomerization in the reaction of cis-2-butene-1,4-diol over supported catalysts: the role of Group VIII transition metals in driving the products selectivity

Maria Grazia MUSOLINO;MAURIELLO F;R. PIETROPAOLO
2010

Abstract

Silica supported Group VIII metal catalysts (Pd, Pt, Ru, Rh and Ir) have been tested at 303K in liquid phase reaction of cis-2-butene-1,4-diol with hydrogen at atmospheric pressure. The catalysts have been characterized by TPR, XRD and TEM. The catalytic activity changes in the order: PdRh > Pt > Ru > Ir. Significant differences were observed in products distribution. Ir/SiO2 and Pt/SiO2 favour the hydrogenation reaction to butane-1,4-diol, whereas Rh/SiO2, Pd/SiO2 and Ru/SiO2 significantly promote double bond and geometric isomerization processes, leading to 2-hydroxytetrahydrofuran and trans-2-butene-1,4-diol, respectively. Formation of products, deriving from isomerization and hydrogenation reactions, is explained on the basis of a mechanism involving a common -alkyl metal bonded intermediate and the variation in products distribution among the various metals is rationalized taking into account electronic factors.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.12318/5220
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