Au/TiO2 nanostructured catalyst:: effects of gold particle sizes on CO oxidation at 90 K

An FTIR study of CO adsorption and oxidation at 90 K on gold-titania catalysts is presented, concerning three nanostructured Au/TiO2 catalysts, with the same gold loading, calcined at three different temperatures and with different gold particle mean sizes of 2.4, 2.5 and 10.6 nm. On all the samples, the CO adsorption and different CO-O-18(2) interactions were examined. From the experimental results, it can be deduced that: (i) at 90 K, carbon monoxide and oxygen are molecularly and competitively adsorbed on gold step sites; (ii) the reaction of (COO)-O-16-O-18 formation occurs if carbon monoxide is pre-adsorbed on the calcined small particles, while it is almost completely inhibited if oxygen is pre-adsorbed; and (iii) on the sample with size 10.6 nm, the reaction does not occur at all at 90 K. The role of the concentration of step sites on the mechanism of the reaction is discussed. (C) 2001 Elsevier Science B.V. All rights reserved.