Effect of thermal treatment on various characteristics of undoped and V2O5-doped Co3O4/TiO2 catalysts

Catalytic and physical characteristics of axially modified cobalt (III) tetraphenyl porphyrin immobilized on chemically different supports

“…The dissolution was carried out in a mixture of CHCl 3 /DMF (1:1 by volume) applying the same procedure described previously [22,23,31]. Estimation of this fraction was followed up spectophotometrically at l max = 416 nm for the complex and 510 nm for the ligand [22].…”

“…The degree of dispersion of the supported complex in the prepared samples was calculated from H 2 chemisorption isotherms measured at room temperature in a micro-volumetric apparatus [31]. A standard pretreatment of the different samples involved outgassing at room temperature for 2 h at p $ 10 À5 Torr (1 Torr = 1.33 Â 10 2 Pa).…”

“…These values were converted into number of surface complex molecules per gram complex, [n CoPM ]. The surface area of the supported complex (S CoPM ), could be calculated by applying the equation [31], S CoPM = (Ns CoPM /M)D, where N is the Avogadro's number, s CoPM is the cross-sectional area of one complex molecule taken, to first approximation, as 152.5 Â 10 À20 m 2 [33], M is the molecular weight of the complex and D is the degree of complex dispersion, being calculated as the ratio of [n H 2 ] or equivalently [n CoPM ]: total number of complex molecules in the sample, [N CoPM ] tot [23].…”

“…The catalase-like activities were evaluated from the gasometric measurements of the volume of O 2 in the decomposition reaction of H 2 O 2 at pH 10, where it is present as perhydroxyl ions, HO 2 À [31]. The activity parameter (A), denoting the number of H 2 O 2 molecules decomposing per second per gram of active complex phase on the support surface, was calculated applying the equation described elsewhere [33,34].…”

“…The chemisorption technique of H 2 and O 2 was used widely in our laboratories to study the mode of dispersion of surface species in several supported cobalt metal, metal oxide and metal complex systems [23,31,34,35]. Molecular adsorption of O 2 was reported for a number of metal phthalocyanines (MPc) and tetraphenyl porphyrines (MTPP), taking place on the central metal ion [39,40], which could be accessible for O 2 either from one side or from both sides of the complex, depending on the nature of the support and the mode of complex-support interaction [23,24].…”