IR study of CO adsorption at 77K on alfa-Al2O3

The low-temperature (77 K) adsorption of CO onto a low surface area microcrystalline specimen of alfa-Al203 has been studied by FTIR spectroscopy. CO uptake yields a broad complex absorption, in which (at least) two poorly resolved componenbare present, ascribed to the weak sigma-coordination onto coordinatively unsaturated Al ions in octahedral coordination, and to the interaction with surface OH groups. Though hardly observable in the vOH spectral region, OH groups are still present also after activation at hi& temperatures, and are perturbed by CO uptake.