Kinetics of irreversible chemisorprion: Surface reduction of MnO₂ by cyclohexane, cyclohexene, and 1,3- and 1,4-cyclohexadiene

The surface reduction of MnO₂ by cyclohexane, cyclohexene, and both 1,3- and 1,4-cyclohexadiene produces benzene and water. A kinetic study and electrical measurements were performed in order to determine the rate-determining step of the reduction. The variations of the rate with temperature are identical to the variations of the number of active oxygen atoms; the apparent activation energy increases in the order cyclohexadienes (7.2 kcal/mole), cyclohexene (8 kcal/mole) and cyclohexane (11 kcal/mole). It has been found that it is the activation of the surface oxygen under the influence of the organic compound-by means of the CH bond-which determines the rate.