REACTION NETWORK AND KINETICS FOR THE CATALYTIC-OXIDATION OF TOLUENE OVER V2O5

The oxidation of three methyl-diphenylmethane isomers and of bibenzyl, benzyl alcohol, and benzaldehyde, which are intermediates in the catalytic oxidation of toluene over V2O5, has been studied to elucidate the reaction network and relative importance of various reactions. Selectivity dependences reveal that the network is composed mainly of three parallel reaction routes: (1) sidechain oxidation with consecutive reactions, (2) oxidative coupling with both parallel and consecutive reactions, and (3) carbon oxide formation. Coupling products are not negligible, with an initial selectivity of 29% (400°C). Anthraquinone is produced mainly from o-methyl-diphenylmethane through o-methyl-diphenylmethanone. Initial ring oxidation products were not found with the conditions and catalyst used. Selectivity depencences suggested product lumping and a simplified network. Kinetic analysis of this reaction network indicates that higher temperatures favor route 2 over route 1. The same initial intermediates for route 1 of side-chain oxidation and for route 2 of oxidative coupling are suggested. © 1990.