A theoretical and experimental study of manganese oxides used as catalysts for VOCs emission reduction

LUCIANO LAMAITA, MIGUEL PELUSO, JORGE SAMBETH, HORACIO THOMAS, GIULIANO MINELLI, PIERO PORTA

CATALYSIS TODAY

Elsevier

Lugar: Amsterdam; Año: 2005 vol. 107 p. 133 - 138

0920-5861

Abstract Complete oxidation of ethanol, as model volatile organic compound, was investigated on manganese oxides catalysts. The catalysts were prepared by two different methods: (1) oxidative decomposition of MnCO3 under flowing oxygen saturated with water and (2) oxidation of a MnSO4 dissolved in H2SO4. The solids were characterized by XRD, diffuse reflectance IR spectroscopy (DRIFTS), DRS–UV–vis and thermogravimetric analyses (TGA). The results showed that both solids belonged to the nsutite phase (g-MnO2). Both catalysts showed similar catalytic activity in the complete oxidation of ethanol. The maximum activity of the catalysts was related to the structure of the catalysts (Mn4+ vacancies, presence of Mn3+ ions and OH groups). The catalyst obtained by decomposition of MnCO3 is the best catalyst because it is easier to prepare. The theoretical results revealed two possible adsorption–oxidation sites of C2H5OH on the nsutite phase; the OH groups formed from Mn4+ vacancies, where ethanol could be oxidized to CO2 and the terminal oxygen of the pyrolusite lattice, where ethanol could be partially oxidized to acetaldehyde, which it could be oxidized to CO2.3 under flowing oxygen saturated with water and (2) oxidation of a MnSO4 dissolved in H2SO4. The solids were characterized by XRD, diffuse reflectance IR spectroscopy (DRIFTS), DRS–UV–vis and thermogravimetric analyses (TGA). The results showed that both solids belonged to the nsutite phase (g-MnO2). Both catalysts showed similar catalytic activity in the complete oxidation of ethanol. The maximum activity of the catalysts was related to the structure of the catalysts (Mn4+ vacancies, presence of Mn3+ ions and OH groups). The catalyst obtained by decomposition of MnCO3 is the best catalyst because it is easier to prepare. The theoretical results revealed two possible adsorption–oxidation sites of C2H5OH on the nsutite phase; the OH groups formed from Mn4+ vacancies, where ethanol could be oxidized to CO2 and the terminal oxygen of the pyrolusite lattice, where ethanol could be partially oxidized to acetaldehyde, which it could be oxidized to CO2.