Oxygen chemisorption by γ-Al2O3 phthalocyaninato cobalt(II). Influence of the surface species γ-Al2O3 on O –2 fixation

Abstract

The degree of hydration of the γ-Al₂O₃ surface governs (a) the type of interaction between phthalocyaninato cobalt(II), [Co(pc)], and γ-Al₂O₃; (b) the activation of [Co(pc)] towards O₂ reduction; (c) the fixation of O^–₂ to Al³⁺ centres.

Thermal, spectroscopic and spectromagnetic analyses show that: (a) the complex [Co(pc)] interacts with the support, as expected for a basic molecule fixed to an acidic surface; (b) O₂ is reduced by the cobalt complex; (c) the initial stage of interaction between γ-Al₂O₃[Co(pc)] and O₂ is formation of the adduct [Co(pc)]O₂ on the γ-Al₂O₃ surface, followed by O^–₂ fixation on the Al³⁺ centres. Competition exists between [Co(pc)] and Al³⁺ as for O^–₂ coordination.