Highly dispersed silver nanoparticles supported on a hydroxyapatite catalyst with different morphologies for CO oxidation

Supported nano-silver (nano-Ag) catalysts have been widely used in heterogeneous catalysis. However, their poor thermal stability restricts their practical application. In order to solve this issue, we report a novel supported nano-Ag catalyst by employing the strong metal-support interactions (SMSIs) between the Ag nanoparticles (NPs) and hydroxyapatite (HAP). The home-made HAP was prepared via a facile hydrothermal or co-precipitation method, which can effectively anchor small size Ag NPs prepared by an impregnation method. Taking advantage of the unique confinement effect with different morphology HAP and the protective effect of hydroxyl groups on the HAP surface, highly dispersed Ag NPs were obtained. These Ag/HAP catalysts were characterized by XRD, N-2 physical adsorption, SEM, TEM and XPS. It was found that the particle size of Ag NPs was strongly related to the morphology and structure of the HAP supports, and it significantly affects the CO oxidation performance. The nano-Ag catalyst with a lamellar nanosheet structure HAP has the highest content of Ag-0, and 100% CO conversion can be achieved at 160 degrees C. The Ag NPs loaded on HAP nanosheets with a large specific surface area showing excellent CO oxidation activity demonstrating that the strategy may open a new way to design and develop highly dispersed nano-Ag catalysts for heterogeneous catalysis.