Pyridine adsorption on α-Fe2O3 has been studied by IR spectroscopy. The splitting of the 8a band of chemisorbed pyridine at infrared beam temperature has been interpreted as due to the existence on the haematite surface of at least two types of Lewis acid sites, possibly tetrahedrically and octahedrically coordinated cations, with a medium electron acceptor strength. Chemisorbed pyridine undergoes chemical transformations under heating, producing at 150°C a species identified, from the comparison of its spectrum with that of bipyridyl chemisorbed on the same surface, as 2,2′-bipyridyl in cis form. The reaction is probably realized via radical-anion formation, so confirming the electron transfer ability of haematite surface. At 400°C both pyridine and bipyridyl transform into a new species, without the opening of pyridine rings. © 1981.
Infrared study of chemisorption and reactivity of pyridine on haematite
BUSCA, GUIDO;
1981-01-01
Abstract
Pyridine adsorption on α-Fe2O3 has been studied by IR spectroscopy. The splitting of the 8a band of chemisorbed pyridine at infrared beam temperature has been interpreted as due to the existence on the haematite surface of at least two types of Lewis acid sites, possibly tetrahedrically and octahedrically coordinated cations, with a medium electron acceptor strength. Chemisorbed pyridine undergoes chemical transformations under heating, producing at 150°C a species identified, from the comparison of its spectrum with that of bipyridyl chemisorbed on the same surface, as 2,2′-bipyridyl in cis form. The reaction is probably realized via radical-anion formation, so confirming the electron transfer ability of haematite surface. At 400°C both pyridine and bipyridyl transform into a new species, without the opening of pyridine rings. © 1981.
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