1. Temperature and Isotope Dependent Kinetics of Nickel-Catalyzed Oxidation of Methane by Ozone
- Author
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Nicholas S. Shuman, Melanie C. White, Brendan C. Sweeny, David C. McDonald, Joshua J. Melko, Albert A. Viggiano, Shaun G. Ard, and Jennifer E. Ruliffson
- Subjects
010405 organic chemistry ,Chemistry ,Kinetics ,Non-blocking I/O ,Analytical chemistry ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Methane ,0104 chemical sciences ,Catalysis ,Reaction coordinate ,Nickel ,chemistry.chemical_compound ,Reaction rate constant ,Catalytic cycle ,Physical and Theoretical Chemistry - Abstract
The temperature dependent kinetics of Ni+ + O3 and of NiO+ + CH4/CD4 are measured from 300 to 600 K using a selected-ion flow tube apparatus. Together, these reactions comprise a catalytic cycle converting CH4 to CH3OH. The reaction of Ni+ + O3 proceeds at the collisional limit, faster than previously reported at 300 K. The NiO+ product reacts further with O3, also at the collisional limit, yielding both higher oxides (up to NiO5+ is observed) as well as undergoing an apparent reduction back to Ni+. This apparent reduction channel is due to the oxidation channel yielding NiO2+* with sufficient energy to dissociate. 4NiO+ + CH4 (CD4) (whereas 4NiO+ refers to the quartet state of NiO+) proceeds with a rate constant of (2.6 ± 0.4) × 10–10 cm3 s–1 [(1.8 ± 0.5) × 10–10 cm3 s–1] at 300 K and a temperature dependence of ∼T–0.7±0.3 (∼T–1.1±0.4), producing only the 2Ni+ + 1CH3OH channel up to 600 K. Statistical modeling of the reaction based on calculated stationary points along the reaction coordinate reproduces ...
- Published
- 2018