Catalytic hydrogenolysis, with high conversion and selectivity,promoted by supported palladium substrates in isopropanol and dioxane at a low H2 pressure (0.5 MPa), is reported for the first time. The catalysts, characterized by using BET isotherms, transmission electron microscopy (TEM), temperature-programmed reduction (TPR), powder X-ray diffractio(XRD), and X-ray photoelectron spectroscopy (XPS), were obtained by coprecipitation and impregnation techniques. The coprecipitation method allows catalysts with a metal–metal or a metal–support interaction to be obtained, which enhances the catalytic performance for both the conversion of glycerol and the selectivity to 1,2-propanediol. Analogous reactions carried out with catalysts prepared by using impregnation are less efficient. A study of the solvent and temperature effect is also presented. The obtained results allow the hydrogenolysis mechanism to be inferred; this involves both the direct replacement of the carbon-bonded OH group by an incoming hydrogen or the formation of hydroxyacetone as an intermediate, which subsequently undergoes a hydrogenation process to give 1,2-propanediol. Finally, catalytic tests on a large-scale reaction at a higher H2 pressure and recycling of the samples were carried out with the better performing catalysts (Pd/CoO and Pd/Fe2O3 prepared by using coprecipitation) to verify possible industrial achievements.

Glycerol Hydrogenolysis Promoted by Supported Palladium Catalysts

Maria Grazia MUSOLINO;FRANCESCO MAURIELLO;ROSARIO PIETROPAOLO
2011

Abstract

Catalytic hydrogenolysis, with high conversion and selectivity,promoted by supported palladium substrates in isopropanol and dioxane at a low H2 pressure (0.5 MPa), is reported for the first time. The catalysts, characterized by using BET isotherms, transmission electron microscopy (TEM), temperature-programmed reduction (TPR), powder X-ray diffractio(XRD), and X-ray photoelectron spectroscopy (XPS), were obtained by coprecipitation and impregnation techniques. The coprecipitation method allows catalysts with a metal–metal or a metal–support interaction to be obtained, which enhances the catalytic performance for both the conversion of glycerol and the selectivity to 1,2-propanediol. Analogous reactions carried out with catalysts prepared by using impregnation are less efficient. A study of the solvent and temperature effect is also presented. The obtained results allow the hydrogenolysis mechanism to be inferred; this involves both the direct replacement of the carbon-bonded OH group by an incoming hydrogen or the formation of hydroxyacetone as an intermediate, which subsequently undergoes a hydrogenation process to give 1,2-propanediol. Finally, catalytic tests on a large-scale reaction at a higher H2 pressure and recycling of the samples were carried out with the better performing catalysts (Pd/CoO and Pd/Fe2O3 prepared by using coprecipitation) to verify possible industrial achievements.
glycerol; heterogeneous catalysis; hydrogenolysis; palladium; sustainable chemistry
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12318/7614
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