Platinum catalysts supported on silicas: effect of silica characteristics on their catalytic activity in carbon monoxide oxidation
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Platinum catalysts supported on silicas with various physicochemical properties were prepared in order to investigate the effect of silica characteristics on their platinum dispersion and catalytic activity in the oxidation of carbon monoxide. Although titania-incorporation into silica and further treatment of the impregnated platinum precursor with hydrogen peroxide were effective for improving the dispersion and stability of platinum catalysts supported on silicas, regardless of the characteristic of the silicas, the platinum catalysts supported on fumed silica with a medium level of surface hydroxyl group concentration exhibited the highest catalytic activity among those supported on mesoporous silica, silica gel, and precipitated silica. The required properties of the highly active platinum catalyst seemed to be a high dispersion of platinum, the formation of a stable titania layer, and the generation of strong acid sites. By contrast, the precipitated silica with a small surface area and high concentration of surface hydroxyl groups was not appropriate for a catalytic support for platinum catalysts.
KeywordsPlatinum Silica support Titania Dispersion CO oxidation
This work was supported by the Ministry of Education, Science and Technology, Republic of Korea (2010) (“The support Program for the Advancement of National Research Facilities Equipment”). TEM photos of the platinum catalysts were obtained from the Korea Basic Science Institute, Gwangju Branch. We also acknowledge the Pohang Accelerator Laboratory for the XAFS measurements.
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