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

• Published in: Catalysis today Vol. 107; pp. 133 - 138
• Main Authors: Lamaita, Luciano, Peluso, M. Andrés, Sambeth, Jorge E., Thomas, Horacio, Mineli, Giuliano, Porta, Piero
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 30.10.2005; Elsevier Science
• Subjects: Catalysis; Chemistry; DRIFTS; Exact sciences and technology; Extended Hückel method (EHMO)-ASED; General and physical chemistry; Manganese oxides; Nsutite; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; VOCs; VOCs; Manganese oxides; Extended Hückel method (EHMO)-ASED; Nsutite; DRIFTS; Theoretical study; Volatile organic compound; Experimental study; Chemical reduction; Infrared spectrometry; Heterogeneous catalysis; Catalyst; Environmental protection
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2005.07.155

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 MnCO 3 under flowing oxygen saturated with water and (2) oxidation of a MnSO 4 dissolved in H 2SO 4. 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 (γ-MnO 2). 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 (Mn 4+ vacancies, presence of Mn 3+ ions and OH groups). The catalyst obtained by decomposition of MnCO 3 is the best catalyst because it is easier to prepare. The theoretical results revealed two possible adsorption–oxidation sites of C 2H 5OH on the nsutite phase; the OH groups formed from Mn 4+ vacancies, where ethanol could be oxidized to CO 2 and the terminal oxygen of the pyrolusite lattice, where ethanol could be partially oxidized to acetaldehyde, which it could be oxidized to CO 2.