F-type centres can be produced by contacting the MgO surface with Mg vapour at ~873 K. CO adsorption at 77 K on such a Mg/MgO system was studied by infrared spectroscopy. Comparison with CO adsorption at 77 K on undoped MgO shows that, besides the monomeric, dimeric and trimeric species observed on pure MgO, new carbonylic entities are formed on Mg doped MgO. Two isomeric structures of C202’-, acetylenediolate ions and other carbonylic compounds which have Mg,(CO), and/or possibly CO- formula are produced. C20a2- species are very sensitive to oxygen. These data confirm that Ftype centres produced on Mg/MgO are very reactive toward simple molecules and strengthen the opinion that the spectroscopic and adsorptive properties of such special sites cannot be confused with those of active centres present on the surface of thermally activated MgO.
Novel dimeric species produced by CO interaction with surface F-Type centres on Mg-doped MgO: an IR study
COLUCCIA, Salvatore;MARTRA, Gianmario;GIAMELLO, Elio;
1991-01-01
Abstract
F-type centres can be produced by contacting the MgO surface with Mg vapour at ~873 K. CO adsorption at 77 K on such a Mg/MgO system was studied by infrared spectroscopy. Comparison with CO adsorption at 77 K on undoped MgO shows that, besides the monomeric, dimeric and trimeric species observed on pure MgO, new carbonylic entities are formed on Mg doped MgO. Two isomeric structures of C202’-, acetylenediolate ions and other carbonylic compounds which have Mg,(CO), and/or possibly CO- formula are produced. C20a2- species are very sensitive to oxygen. These data confirm that Ftype centres produced on Mg/MgO are very reactive toward simple molecules and strengthen the opinion that the spectroscopic and adsorptive properties of such special sites cannot be confused with those of active centres present on the surface of thermally activated MgO.
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