Heats of adsorption of linear CO species adsorbed on the Au-circle and Ti+delta sites of a 1% Au/TiO2 catalyst using in situ FTIR Spectroscopy under adsorption equilibrium

摘要

The heats of adsorption of two linear CO species adsorbed on the Audegrees particles (denoted L-Audegrees) and on the Ti+delta sites (denoted LTi+delta) of a 1% Au/TiO2 catalyst are determined as the function of their respective coverage by using the AEIR procedure (adsorption equilibrium infrared spectroscopy) previously developed. Mainly, the evolutions of the IR band area of each adsorbed species (2184 cm(-1) for LTi+delta and at 2110 cm(-1) for L-Audegrees) as a function of the adsorption temperature T-a, at a constant CO adsorption pressure P-CO, provide the evolutions of the coverages theta(LTi+delta) and theta(LAudegrees). of each adsorbed CO species with T-a in isobar conditions that give the individual heats of adsorption. It is shown that they linearly vary from 74 to 47 kJ/mol for L-Audegrees and from 50 to 40 kJ/mol for LTi+delta at coverages 0 and 1, respectively. These values are consistent with literature data on model Au particles and TiO2. In particular, it is shown that the mathematical formalism supporting the AEIR procedure can be applied to literature data on Au-containing solids (single crystals and model particles).