The kinetics of dehydrocyclization of n-hexane on rhodium and copper-rhodium films

The effect of copper present in amounts of a 0.3 and 0.5 monolayer on the catalytic activity of a continuous rhodium film in the formation of cyclohexane was studied in the temperature and hexane pressure ranges 560-733 K and 0.6-10 Pa, respectively. A higher activity of RhCu compared with Rh was explained by the formation of bimetallic active centers. The introduction of copper increased the experimental activation energy of the reaction (Ea). Depending on the conditions, the rate of the reaction either did not depend on the initial hexane pressure p0 or increased proportionally to p0 on Rh and to ∼ p1/20 on RhCu. For RhCu (0.5 monolayer), the rate of catalyst cooling (fast or slow) after thermal treatment influenced the rate of the reaction and the Ea value.