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 cataly sts is presented, concerning three nanostructured Au/TiO2 catalysts, with t he same gold loading, calcined at three different temperatures and with dif ferent 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. Fr om the experimental results, it can be deduced that: (i) at 90 K, carbon mo noxide and oxygen are molecularly and competitively adsorbed on gold step s ites; (ii) the reaction of (COO)-O-16-O-18 formation occurs if carbon monox ide is pre-adsorbed on the calcined small particles, while it is almost com pletely inhibited if oxygen is pre-adsorbed; and (iii) on the sample with s ize 10.6 nm, the reaction does not occur at all at 90 K. The role of the co ncentration of step sites on the mechanism of the reaction is discussed. (C ) 2001 Elsevier Science B.V. All rights reserved.