Preferential oxidation of CO in H₂ stream on Au/CuO-CeO₂ catalysts: Effects of calcination temperature

Nanoscaled gold particle supported on CuO-CeO₂ was used for preferential oxidation of carbon monoxide in hydrogen stream (PROX). CuO-CeO₂ support was prepared by co-precipitation method in order to incorporate more CuO into CeO₂ lattice. Gold was loaded on the support by deposition-precipitationmethod. These catalysts were characterized by N₂-sorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM), and X-ray photoelectron spectroscopy (XPS). The PROX reaction was carried out in a fixed bed continuous flow reactor with a feed of CO:O₂:H₂:He = 1.33:1.33:65.33:32.01 in volume ratios. CO/O₂ molar ratio was fixed at 1 in the feed in order to magnify the difference between different catalysts. The particle size of gold was around 2-5 nm and Au particles were dispersed well on the support. CuO was incorporated into the lattice structure of CeO₂, resulting in increasing the lattice oxygen vacancy. The excess CuO would be on the surface of CeO₂. The incorporation of copper ion into ceria lattice promoted the oxygen storage capacity of ceria support and enhanced the activity of catalyst. The higher calcination temperature for the support resulted in higher crystallinity of CeO₂, leading to the higher activity. The CO selectivity increased with increasing CuO content. However, overloading of CuO would retard the CO conversion and selectivity of oxygen reacting with CO. The results showed that the catalyst with optimum CuO content and high calcination temperature could reach 100% CO conversion in hydrogen stream at the PEM fuel cells operating temperature (80-100 °C).