Synthesis and catalytic activity of manganese dioxide (type OMS-2)

M. ANDRÉS PELUSO; LUIS GAMBARO; ESTELA PRONSATO; DELIA GAZZOLI; HORACIO J. THOMAS; JORGE E. SAMBETH

CATALYSIS TODAY

Elsevier

Lugar: Londres; Año: 2008 vol. 133 p. 487 - 492

0920-5861

Two solids were synthesized by the reaction between Mn2+ and KMnO4 in different order. The results of the characterization of both solidsshowed that: (i) they are poorly crystalline, although both belong to the Cryptomelane (OMS-2) phase; (ii) these materials are mesoporous(mesopores concentration in the order of 80%); (iii) they contain the couple Mn3+/Mn4+, being the Mn3+ concentration a function of the preparationmethod. Both catalysts were analyzed in the total oxidation of ethanol and the percentage of ethanol conversion on both solids reached 50% at155 8C. The adsorption studies of methanol and ethanol have demonstrated the presence of basic sites and two different adsorption sites. Theanalysis of the results suggest that the amount of adsorbed ethanol molecules and the lowest temperature of CO2 desorption detected is due to theMn3+ concentration. This phenomenon is ascribed to a high concentration of Mn3+ which could originate a weak Mn–O bond and the formation ofmore active oxygen species which would improve the catalytic performance.Keywords: Cryptomelane; Manganese oxide; TPD-MS; VOCs elimination