Hydrogenation Of Angelica Lactone On Supported PdNi Catalysts With Synergistic Effect

The usage of supported bimetallic catalysts in heterogeneous catalysis,including biomass conversion usually leads to great atomic efficiency of the reaction processes.Alpha-angelica lactone(α-AL)has been recently regarded as a new platform molecule,from which many useful chemicals can be synthesized.This thesis mainly focuses on the hydrogenation of α-AL over a Pd-NiO(Ni)bimetallic catalyst.The content consists two parts:1.The NiO(Ni)/SiO2 materials with different Ni loading(2-40 wt.%)supported very low Pd loading(0.2 wt.%)was prepared.The hydrogenation of α-AL to GVL can be successfully performed under mild conditions over a series of Pd-xNiO/SiO2 catalysts.Metallic Ni significantly suppressed the hydrogenation activity of Pd nanoparticles supported thereof.Pd-O-Ni species formed by the intimate interaction between Pd and NiO tend to be the active site.2.A systematical study on the hydrogenation activity of palladium-nickel bimetallic catalysts with varying oxidation states and particle sizes of nickel species has been carried out.The Pd-NiO/SiO2 catalysts with oxidized NiO surface show more stable activity and better coke-resistance in hydrogenation in both water and tetrahydrofuran than the reduced counterparts.The reduced Pd-Ni/SiO2 catalysts deactivate with time on stream in tetrahydrofuran and the activity loss is particle size dependent,with smaller Ni particle size showing the better stability.Water as a green solvent serves as a superior reaction medium to aprotic solvents such as tetrahydrofuran.