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Ind. Eng. Chem. Res. 2009, 48, 5666–5670
Preferential Oxidation of CO in H2 Stream on Au/TiO2 Catalysts: Effect of Preparation Method Palanivelu Sangeetha, Li-Hsin Chang, and Yu-Wen Chen* Department of Chemical and Materials Engineering, National Central UniVersity, Chungli 320 Taiwan
A series of Au/TiO2 catalysts were prepared by either photodeposition or deposition-precipitation methods. The catalysts were characterized by inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The catalytic performance of these catalysts was investigated by preferential oxidation of carbon monoxide in a hydrogen stream. A high gold dispersion and narrow size distribution was obtained for Au/TiO2 catalysts prepared by both photodeposition or deposition-precipitation methods. The photodeposition method facilitates the preparation of gold particles as small as 1.5 nm on the support, whereas in the deposition-precipitation method, the gold particles were found to be around 2-3 nm. The catalyst prepared by the photodeposition method showed higher CO conversion and CO selectivity than those prepared by the deposition-precipitation method. The selectivity of CO reacting with O2 decreased with increasing reaction temperature due to H2 competing with CO at high temperatures. Au/TiO2 catalysts prepared by the photodeposition method showed relatively higher CO selectivity below 65 °C when compared with the deposition-precipitation method. The differences in activity could be attributed to the difference in chemical state of gold particles and the particle size of gold. The catalyst prepared by photodeposition had a smaller particle size (1.5 nm). It had higher CO conversion at low temperature (
