Effects of various alkali-acid additives on the activity of a manganese oxide in the catalytic combustion of ketones

The catalytic combustion of acetone and methyl-ethyl-ketone (MEK) has been studied over a manganese oxide, Mn2O3, The reactant conversion has been fol lowed as a function of the reaction temperature and it has been observed th at lower temperatures are required for the combustion of acetone than for M EK. The performance of Mn2O3 in the, combustion reactions when alkali and a cid ions are added to the oxide has also been investigated. A significant i mprovement of the catalyst performance is observed when Cs+ and Na+ are use d as additives. The data of the ignition curves have been fitted to a simpl ified model where both ketone combustion reactions are assumed to have powe r law rate equations, which are first-order with respect to the correspondi ng organic molecule and do not depend on the oxygen partial pressure. Diffe rences in the apparent activation energy values estimated with this model f or acetone and MEK combustion are significant only when acid ions additives are present. (C) 2001 Elsevier Science B.V. All rights reserved.