Über Kinetik und Reaktionsmechanismus der Oxydation von Acetaldehyd in flüssiger Phase

Abstract

The oxidation of acetaldehyde in the liquid phase with molecular oxygen (air) at 75 °C and 30 at has been studied. Acetic acid is formed generally through the intermediate peracetic acid, but also by a simultaneous step through diacetyl. The latter is formed by dimerisation of acetyl-radicals and gives through further oxidation, beside acetic acid, a certain amount of carbon dioxide and water. By the means of kinetic analysis, it is shown that two routes lead to the simultaneous formation of carbon dioxide and methane. One is the direct degradation of acetaldehyde and the other is the degradation of acetic acid. The former is neither influenced by catalyst concentration nor by air-throughput, but the degradation of acetic acid can be practically avoided by increasing the amount of the catalyst. Catalyst concentration and air-throughput are alternating with each other in that sense that with increasing catalyst concentration and decreasing air-throughput, the selectivity of acetic acid formation is increased. On the basis of the kinetic analyses a new formulation of the microreaction mechanism is proposed.