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| Low-temperature CO oxidation over Au-doped OMS-2 catalysts: preparation and catalytic activity |
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Abstract Au/OMS-2 catalysts were prepared by pre-incorporation (QI), typical wet impregnation (IM) and deposition-precipitation (DP) methods. The influences of prepared methods and conditions on the catalytic activity of CO oxidation were studied. The samples were characterized by X-ray diffraction (XRD) and Brunaner-Emmett-Teller (BET). As compared with pre-incorporation and typical wet impregnation methods, Au/OMS-2-DP prepared from deposition-precipitation (DP) method revealed the highest activity, due to the largest surface area and the smallest Au particle size. A study was conducted on the effects of different preparation conditions (i.e., precipitating agents, pH of solution, Au loading and calcinations temperature) on the catalytic oxidation of CO over Au/OMS-2-DP. Effects of precipitating agents on catalytic activity were obvious. The best catalytic activity was shown by the Au/OMS-2-DP catalyst prepared with KOH as a precipitating agent, which could be explained in terms of the smallest Au particle size. A pH of 9 generated greater amounts of Au loading and smaller Au particles on OMS-2 than other pH value. The sample calcined at 300℃ showed the highest activity, which may be due to the sample’s calcined at 200℃ inability to decompose completely to metallic gold while the sample calcined at 400℃ had larger particles of gold deposited on the support. Au/OMS-2-DP prepared from a gold solution with KOH as a precipitating agent, pH of 9, Au loading at 5 wt%, and a calcination temperature of 300℃ provides the optimum catalytic activity for CO oxidation, i.e. 100% CO conversion at 67℃.
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Received: 01 July 2011
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| [1] |
. [J]. CHINA ENVIRONMENTAL SCIENCECE, 2002, 22(1): 0-0. |
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