Comparison of the Coverage of the Linear CO Species on Cu/Al2O3 Measured under Adsorption Equilibrium Conditions by Using FTIR and Mass Spectroscopy

The adsorption of CO at several adsorption temperatures T a in the range of 300−480 K on a reduced 4.7%Cu/Al 2 O 3 catalyst is studied by both FTIR spectroscopy and a volumetric method using a mass spectrometer as the detector. Only a linearly adsorbed CO species is detected with an IR band at 2092 cm -1 at 300 K after adsorption of 1%CO/He. The coverages θ L of this adsorbed CO species at several adsorption temperatures are determined using either the amount of adsorbed CO (volumetric method) or the IR band area, assuming a linear relationship with the amount of adsorbed species on the surface. The two analytical methods provide the same values of the coverage of the L species in the range of θ L = 0−1. This proves that the assumption involved in the quantitative exploitation of the FTIR spectra is valid and that quantitative studies using FTIR spectra of the adsorbed CO species (i.e., determination of the heat of adsorption of the L species) can be reasonably performed.