Hydrogenolysis of glycerol on bimetallic Pd-Cu/solid-base catalysts prepared via layered double hydroxides precursors

A series of bimetallic Pd-Cu/solid-base catalysts were prepared via thermal decomposition of PdxCu0.4Mg5.6−xAl2(OH)16CO3 layered double hydroxides precursors and used in hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO). X-ray diffraction (XRD), scanning electron microscopy (SEM) and N2O oxidation and followed H2 titration characterizations confirmed that well structured layered double hydroxides PdxCu0.4Mg5.6−xAl2(OH)16CO3 crystals could be prepared when the amount of added Pd was less than x < 0.04. Pd and Cu dispersed highly in reduced PdxCu0.4/Mg5.6−xAl2O8.6−x and Pd improved the reduction of Cu. Hydrogenolysis of glycerol proceeded easily on bimetallic Pd-Cu/solid-base catalysts than separated Pd and Cu. On Pd0.04Cu0.4/Mg5.56Al2O8.56, the conversion of glycerol and selectivity of 1,2-PDO reached 88.0 and 99.6%, respectively, at 2.0 MPa H2, 180 °C, 10 h in ethanol solution. And this catalyst is stable in five recycles. It was concluded that H2-spillover from Pd to Cu increased the activity of PdxCu0.4/Mg5.6−xAl2O8.6−x in hydrogenolysis of glycerol.

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► Pd-Cu bimetallic catalyst exhibited synergistic effect for glycerol hydrogenolysis.
► This synergistic effect was attributed to hydrogen spillover from Pd to Cu.
► Glycerol hydrogenolysis performed sufficiently in ethanol solution.
► Solid base can suppress the cleavage of C–C bond in glycerol.
► Cu leaching in the polar medium would bring deactivation.