Papers by Keyword: PROX

Abstract: AuNP (gold nanoparticle) supported by oxide shows a high reactivity for a PROX (preferential oxiation) reaction at low temperature. Au catalysts were usually prepared by conventional methods such as precipitation, impregnation and vapor phase grafting. In this study, we developed a novel method for the preparation of AuNPs supported on a bimodal nanoporous alumina. The AuNPs were prepared in a toluene phase by the modified Brust method. The metal particle size was able to be controlled from 2 to 50 nm via the control of the surfactant concentrations. The resulting materials were characterized by BET, FE-SEM, TEM, and XRD analyses. After calcinations at 700oC, AuNP/Al2O3 catalyst revealed a bimodal nanoporous structure, with the pore sizes of 3.5 and 7 nm, and demonstrated both a high surface area (350 m2/g) and pore volume (0.9 cm3/g).

Abstract: Au/CeO2 catalysts prepared by a deposition-precipitation and a co-precipitation method were applied to CO oxidation in the absence and presence of hydrogen. The transmission electron microscope (TEM), the temperature programmed reduction (TPR), and the X-ray absorption near edge structure (XANES) were conducted to probe structural and electronic properties of gold. Au2O3 was determined to be mainly present when Au/CeO2 was prepared by a deposition-precipitation method. However, the metallic gold was observed in a co-precipitated Au/CeO2 catalyst. Au/CeO2 containing oxidized gold species, prepared by a deposition-precipitation method, showed the decreasing CO conversion with a reaction time, which accompanied the reduction of gold from Au(+3) to Au(0). However, co-precipitated Au/CeO2 showed the stable CO conversion. The effect of pretreatment condition on CO oxidation was also examined. These results support that Au/CeO2 catalyst containing oxidized gold species was superior to Au/CeO2 catalyst containing the metallic gold for CO oxidation. This Au/CeO2 catalyst was also active for the selective CO oxidation in the presence of hydrogen.