Kinetic isotope effects in the N2O decomposition over NiO

Abstract

The 15N and 18O kinetic isotope effects (KIEs) in the catalytic decomposition of nitrous oxide on NiO powder were determined in the temperature range of 625-825 K, and the following temperature dependencies were found: KIE(15N) = (0.821 ± 0.180) + (1445 ± 128)/T and KIE(18O) = (1.384 ± 0.124) + (1450 ± 89)/T. At initial pressures of N2O between 40 and 60 kPa, the reaction is first order in N2O and has an apparent activation energy of 131 ± 3 kJ mol-1. According to Bigeleisen's formalism, a bent, product-like NNO transition state and a fork-type NNOO transition state best fit the experimental results.