The synthesis and characterization of several dispersed molybdena catalysts on silica support (MoO3-SiO2) prepared from a variety of precursors (Mo(VI)-acetylacetonate, oxo-peroxo Mo-species, hydrated ammonium heptamolybdate) and preparation methods (deposition of the Mo-phase on finite SiO2 support by aqueous and methanol impregnations, by adsorption, by oxo-peroxo route-like, and by one-step synthesis of MoO3-SiO2 system with molecular precursors) are presented. The molybdena concentration on silica was comprised in a large interval (1.5 - 14 wt%) depending on the preparation method which governed the Mo-loading on silica. Convenient comparisons among samples at similar Mo-concentration have been made discussing the morphologic-structural (XRD, XPS, UV-vis-DRS, and N2-adsorption) and physicochemical (TG-DTG, TPR, and n-butylamine-TPD) sample properties. Polymeric octahedral polymolybdate aggregates predominated in the samples prepared by aqueous and methanol impregnations, which were at high Mo-concentration. On the contrary, isolated Mo(VI) species in distorted Td symmetry predominated in the sample prepared by adsorption which was at very low Mo-concentration. The sample acidity was composed of a weak acidy site population, associated with the silica support, and a strong acid site population associated with the Mo-dispersed phase. Oxidation tests of formaldehyde, an oxygen-containing VOC (Volatile Organic Compound), were performed to determine the prevalent redox or acidic function of the Mo-species at the surface of the catalysts.
Property and activity of molybdates dispersed on silica obtained from various synthetic procedures / A. Gervasini, L. Wahba, M.D. Finol, J.F. Lamonier. - In: MATERIALS SCIENCES AND APPLICATIONS. - ISSN 2153-117X. - 3:4(2012), pp. 195-212.
|Titolo:||Property and activity of molybdates dispersed on silica obtained from various synthetic procedures|
GERVASINI, ANTONELLA (Primo) (Corresponding)
|Parole Chiave:||Molybden Characterization; Catalytic Oxidation; Formaldehydea-Silica Mixed Oxides; Molybdenum Dispersed Phase; Catalyst Preparation; Catalyst|
|Settore Scientifico Disciplinare:||Settore CHIM/02 - Chimica Fisica|
|Data di pubblicazione:||2012|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.4236/msa.2012.34030|
|Appare nelle tipologie:||01 - Articolo su periodico|