Basic studies of the kinetics of the reduction of copper oxide were made to establish the effect of the solid phase on the overall reactionnKinetics. The reaction CuO(s) + H2(g) ----> Cu(s)+ H20(g) consisted of an induction stage, an acceleration or autocatalytic stage terminating at about 35$ reduction of the oxide, and a decreasing rate stage. The reduction rates for each stage were dependent on the nature of the initial oxide, the degree of subdivision of the oxide, and the temperature, but were independent of the mass of the oxide phase. Addition of the reaction product copper had no measurable effect on the reaction. 'Water vapor, in concentrations of 25 mg per liter of hydrogen prevented reduction at 112°C The inhibiting effect decreased rapidly as the temperature was increased and disappeared entirely at 190°C. Once reduction had started, water vapor had practically no effect.nThe acceleration and decay stages were very closely approximated by a semiempirical equation based on the initial reaction occurring on certain active nuclei followed by a rapid growth of these nuclei by a branching-chain mechanism. The reduction rate reached a maximum and subsequently decreased as considerable interference occurred among the branching nuclei. Arrhenius plots gave an activation energy of 13-5 ± 1.2 kcal for the reduction.
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