Abstract
The process of pyridine and n-butylamine adsorption and desorption at a pyrogenic aluminium oxide surface has been studied using IR spectroscopy. It has been found that both Lewis and Brönsted acid centres are present on an Al2O3 surface annealed in vacuum at 200°C, with coordination-bonded water possessing stronger proton-donor properties than hydroxy groups. Dehydroxylation of the surface gave rise to new types of strong electron-acceptor centres. The surface hydroxy groups did not exhibit acidic properties at room temperature and formed a hydrogen bond with pyridine, whilst for desorption at elevated temperatures the IR bands observed indicated the formation of a pyridinium ion, i.e. proton transport to the adsorbed base became possible.