Impact of the support on the heat of adsorption of the linear CO species on Pt-containing catalysts

Abstract

It has been previously shown that the individual heats of adsorption of each adsorbed CO species (linear, bridged and three-fold coordinated) on Pt/Al 2O 3 catalysts can be obtained from the change of their characteristic IR bands with the adsorption temperature T a (in the range of 300–800 K) at a constant CO partial pressure P a according to a procedure denoted adsorption equilibrium infrared spectroscopy. In the present study, this procedure is used to reveal the impact of the nature of the support TiO 2, CeO 2 and Y 2O 3/ZrO 2 (two solids with high (104 m 2/g) and low (14 m 2/g) BET surface area) on the heat of the adsorption of the L CO species that dominates the CO adsorption. These reducible supports have been selected because of their expected interactions with Pt particles according to different SMSI effects. In the wavenumber range characteristic of the L CO species on Pt sites, the FT-IR spectra are dependent on the nature of the support: two strongly overlapped IR bands are detected with an intensity ratio depending on the support. However, it is shown that the nature of the support only has a slight impact on the average heats of adsorption of the L CO species (<20 kJ/mol as compared to Pt/Al 2O 3).