Defect Engineering of Supported Metal Catalysts for Selective Hydrogenation

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Supported metal catalysts have been used extensively in industry. To construct supported metal catalysts with low cost and high catalytic performance, high dispersion of metal on the support material is greatly favored in recent years. With the downsizing of metal active phase, new challenges in catalyst synthesis and characterization have emerged. The highly dispersed metal active phase is prone to aggregate to decrease surface free energy, which requires innovative synthesis strategy to stabilize the metal species on support. High metal dispersion also created more interfacial sites and bonds between metal and support, therefore the metal-support interaction has more significant effects on the catalytic properties of high dispersion catalysts. Defect engineering has attracted much attention due to its ability to help stabilizing metal species and tune the metal-support interaction.This dissertation focuses on utilizing defect engineering to develop catalysts with high activity and selectivity in hydrogenation reaction. Harsh pH condition was applied in wetness impregnation process to generate cavity sites on TiO2 support surface, which resulted in stronger metal-support interaction between Pt and TiO2. The catalyst synthesized under harsh condition showed higher hydrogenation activity towards -NO2 group. Laser engraving was used as another defect engineering technique to create defects on TiO2 support. The laser engraved support showed distinct electronic and redox properties, which enhanced the electronic metal-support interaction of Pt and TiO2 support. The Pt/TiO2-LE catalyst showed superior activity and selectivity in the hydrogenation of 3-nitrostyrene and furfural alcohol. In addition, an effective method to probe the metal dispersion of Pt by styrene hydrogenation reaction kinetics was developed. This method has the potential to be applied to other catalysts systems and could be used to study the metal-support interaction in catalysts.