Cyclohexane oxidation with an O2–H2 mixture in the presence of a two-component Pt/C–heteropoly acid catalyst and ionic liquids
- Authors: Kuznetsova L.I.1, Kuznetsova N.I.1
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Affiliations:
- Boreskov Institute of Catalysis, Siberian Branch
- Issue: Vol 58, No 5 (2017)
- Pages: 522-532
- Section: Article
- URL: https://journals.rcsi.science/0023-1584/article/view/163228
- DOI: https://doi.org/10.1134/S0023158417050147
- ID: 163228
Cite item
Abstract
Approaches to increase the efficiency of Pt/C–heteropoly acid catalyst in a liquid-phase oxidation of cyclohexane using an O2–H2 mixture were studied. It was shown that small additives of ionic liquid (BMImBr, Bu4NBr, or Bu4NHSO4) significantly improve the catalytic effect of the Pt/C–H3PMo12O40–CH3CN system at 35°C, by slowing the rate of side reactions resulting in water formation, increasing the rate of oxygenate formation, and inhibiting their secondary oxidation reactions. The efficiency of H2 consumption increases from 2 to 18–25%, while the selectivity of cyclohexane conversion is 92–98%. The substitution of one or two Mo(VI) ions by V(V) in the structure of the heteropoly acid decreases these parameters. In the presence of Bu4NHSO4, a Pt/C catalyst can be used many times. During the reaction, the heteropoly acid present in the solution is in a reduced state under the action of the reaction medium and undergoes reversible redox transformations. The nature of the catalytic action of the studied system is explained from the viewpoint of the effect of ionic liquids on the properties of a Pt/C catalyst in activating O2, heteropoly molybdate chemistry, and the known mechanisms of the peroxide oxidation of hydrocarbons.
Keywords
About the authors
L. I. Kuznetsova
Boreskov Institute of Catalysis, Siberian Branch
Author for correspondence.
Email: livkuzn@catalysis.ru
Russian Federation, Novosibirsk, 630090
N. I. Kuznetsova
Boreskov Institute of Catalysis, Siberian Branch
Email: livkuzn@catalysis.ru
Russian Federation, Novosibirsk, 630090