Impact of ceria loading on the preferential CO oxidation over gold catalysts on CeO2/Al2O3 and Y-doped CeO2/Al2O3 supports prepared by mechanical mixing

Gold catalysts on CeO2/Al2O3 and Y-doped CeO2/Al2O3 supports prepared by mechanical mixing were tested in the preferential CO oxidation in hydrogen rich stream (PROX). The samples were characterised by XRD, HRTEM/HAADF, XPS and TPR measurements and the effect of preparation method on the textural, structural, reductive and catalytic properties was commented. The difference in the catalytic behaviour at the temperatures of interest for fuel cells application (80-120 degrees C) was not very substantial showing a degree of CO conversion in the range of 60 and 70%. An exception was the highest CO conversion at 80 degrees C observed over the gold catalyst on CeO2/Al2O3 with 20 wt.% ceria loading. The explanation of the lower activity of gold catalyst on Y-doped CeO2/Al2O3 with the same ceria amount was related to gold dispersion as a key factor for CO oxidation. The positive effect of yttrium was evidenced during long run tests in PROX with CO2 and water addition to gas stream. The better stability caused by the Y-presence was in agreement with the CO2-TPD results showing lower surface basicity.