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Author: search.filters.author.Coluccia, SalvatoreSubject: search.filters.subject.Infrared spectroscopy

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    Infrared Study of Carbon Monoxide Adsorption on Calcium and Strontium Oxides
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1981, 77 (05), 1981) Coluccia, Salvatore; Garrone, Edoardo; Guglielminotti, Eugenio
    CO adsorption on CaO and SrO takes place, as on MgO, via a disproportionation reaction leading to both surface carbonates and unusual surface species with a complex vibrational spectrum in the low-frequency range. These are thought to be negatively charged CO polymers, the simplest ones being (CO)2–2. A strong electrostatic interaction between negative species and surface cations accounts for the marked dependence of the infrared signal on the lattice parameter of the solids. The increasing basicity along the series MgO, CaO, SrO causes: (i) a marked increase in the total adsorptive capacity; (ii) an increase in the relative population of polymers with respect to dimers; (iii) an increase in the importance of a Boudouart-like reaction upon desorption.
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    I.r. Spectroscopic Study of CO2 Adsorption onto q-Al2O3
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1977, 73 (10), 1977) Morterra, Claudio; Zecchina, Adriano; Coluccia, Salvatore; Chiorino, Anna
    The adsorption of CO2 at room temperature onto η–Al2O3 dehydrated at various temperatures between 25 and 800°C was studied by i.r. and microgravimetric techniques. The following surface species are formed; three σ-coordinated linear structures, two bicarbonates that can be interconverted, several “organic” carbonates and minor amounts of mono- and bi-dentate carbonates. Relative concentrations of these species depend strictly on pretreatment conditions, while the nature of the species is primarily determined by the coordination of surface cations. The overall coverage is quite small, (θ⩽ 10 %) and nearly the same as in all transition aluminas. A cooperative mechanism for CO2 adsorption is thus invoked to account for this and other features. The interaction between CO2 adsorption and catalytic activity is considered, and the probable nature of the centres responsible for exchange and equilibration reactions is suggested.