Catalytic performance of gold nanoparticles using different crystallinity HAP as carrier materials

Gold (Au) was loaded on hydroxyapatite (HAP) supports with three different degree of crystallinity by deposition-precipitation method. Amorphous HAP and higher crystalline HAP nanoparticles were synthesized respectively by a direct precipitation process of which the aging time was 12 h or hydrothermal treatment at 180 °C. CO oxidation reaction was used to evaluate the behavior of catalysts. The physical properties of the catalysts were characterized by BET and TEM. The result found the catalyst with the lowest specific surface area had the highest initial activity. Patterns of XRD and XPS revealed that the HAP supports with higher crystallinity could produce more Au° over their surface which resulted in higher initial activity. This study suggested that the crystallinity of HAP supporter was another main factor to improve catalytic activity despite of specific surface area of the Au/HAP nanocatalysts.