Effect of preparation conditions of Au-Mn co-precipitates for low temperature CO oxidation
Pankhurst, Quentin A.
Wagner, Friederich E.
|Source||Proceedings of the Asia-pacific Chemical Reaction Engineering Symposium "APCRE 99", Hong Kong SAR, China, The Hong Kong University of Science and Technology, Hong Kong SAR, China, 13-16 June 1999,p. 569-574|
|Summary||Au-Mn co-precipitates were dried at different tempertures and in different atmospheres. The co-precipitates were tested for low temperature CO oxidation without any additional thermal treatment. While a sample dried at 120 ℃ in air exhibited the highest activity for oxidation of CO, samples dried at room temperature under vacuum were less active. This result indicates that high-temperature and air drying can affect catalyst performance favourably. The catalytic properties of most fresh samples improved after the first light-off test, during which a temperature of 400 ℃ was reached. To investigate the physical and chemical state of gold and substrate, dried samples were examined by Au Mössbauer spectroscopy, x-ray diffraction (XRD) and transmission electron microscopy (TEM). Au Mössbauer spectra showed that gold existed only in metallic form, even for samples dried at room temperature. XRD analysis demonstrated that fresh samples contained a large amount of manganese carbonate. The carbonate converted to manganese oxides after the light-off test. TEM analysis indicated that the manganese substrate was present in plate-like and needle-like shapes and the shape of gold particles was elliptical or rectangular with rounded corners. The results show that the conditions of drying have a significant effect on the performance of Au-Mn co-precipitates.|
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