Hydrogenation of the aromatic rings of 2-ethylanthraquinone on palladium catalyst

Hydrogenation of anthraquinones at the oxygen is a key step in the industrial production of hydrogen peroxide. The reaction is very fast in the presence of palladium supported catalysts. However, these catalysts also promote the hydrogenation of the aromatic rings of the anthraquinone molecules giving place to substances not participating in the formation of hydrogen peroxide and causing a loss of active quinone. 2-ethylanthraquinone can also give tautomerization to oxanthrone and derivatives with a further loss of active quinone. The kinetics of the hydrogenation of the aromatic rings of 2-ethylanthraquinone are studied. A dual site reaction mechanism well explains the experimental findings. On the basis of this mechanism, kinetic expressions have been developed and the kinetic parameters determined. The contribution of tautomerization to the kinetic pattern has also been ascertained.