Cyclohexane oxidation catalyzed by manganese oxide octahedral molecular sieves—Effect of acidity of the catalyst

Kumar, Ranjit; Sithambaram, Shanthakumar; Suib, Steven L.

doi:10.1016/j.jcat.2009.01.007

Cited by 149 publications

(88 citation statements)

References 30 publications

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“…As the conversion (ca. 6%) is also similar to that obtained from current industrial processes [11,12], this makes MB a promising catalytic system for the oxidation of cyclohexane. Indeed, this is a crucial step for the manufacture of nylon fibres, with cylohexanol used as precursor for nylon-6,6 and cylohexanone as precursor for nylon-6.…”

Section: Introductionsupporting

confidence: 79%

Insights into the Reaction Mechanism of Cyclohexane Oxidation Catalysed by Molybdenum Blue Nanorings

et al. 2015

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Molybdenum blue (MB), is a polyoxometalate with a nanoring structure comprising Mo 5+ -OMo 6+ bridges, which is active for the catalytic oxidation of cyclohexane to cyclohexanol and cyclohexanone. However, little is known about the mechanistic features responsible of this catalytic activity. In the present work, the Mo 5+ -O-Mo 6+ moieties embedded in the MB nanoring structure were characterized using diffuse reflectance-UV-Visible spectroscopy and solid state EPR spectroscopy. The amount of Mo 5+ centres was then varied by thermal treatment of the polyoxometalate in the absence of oxygen, and the resultant effect on the catalytic activity was investigated. It was observed that, an increased amount of Mo 5+ centres preserved the conversion of cyclohexane (ca. 6%) but led to a loss of selectivity to cyclohexanol giving cyclohexanone as the major product, and the simultaneous formation of adipic acid. To rationalise these results the catalysts were studied using EPR spin trapping to investigate the decomposition of cyclohexyl hydroperoxide (CHHP), a key intermediate in the oxidation process of cyclohexane. This analysis showed that CHHP has to be bound to the MB surface in order to explain its catalytic activity and product distribution.

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Section: Introductionsupporting

confidence: 79%

Insights into the Reaction Mechanism of Cyclohexane Oxidation Catalysed by Molybdenum Blue Nanorings

et al. 2015

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“…140 o C) several reaction products can be obtained, (besides cyclohexane and cyclohexane also and adipic acid, and derivatives from ring opening and reactions of -formyl radicals). In view of this, the conversion of this reaction is deliberately limited at around 4-5% in industrial processes, 194,195 with the aim to preserve selectivity to alcohol and ketone above 85%, and minimize by-product formation (Fig. 12).…”

Section: Cyclohexane Oxidation: An Exploited Case Of Autoxidationmentioning

confidence: 99%

Catalytic oxygen activation versus autoxidation for industrial applications: a physicochemical approach

Liu

Ryabenkova

Conte

2015

Phys. Chem. Chem. Phys.

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The activation and use of oxygen for the oxidation and functionalization of organic substrates is among the most important reactions in a chemist's toolbox. Nevertheless, despite the vast literature on catalytic oxidation, the phenomenon of autoxidation, an ever-present background reaction that occurs in virtually every oxidation process, is often neglected. In contrast, autoxidation can affect the selectivity to a desired product, to those dictated by pure freeradical chain pathways, thus affecting the activity of any catalyst used to carry out a reaction.This critical review compares catalytic oxidation routes by transition metals versus autoxidation, particularly focusing on the industrial context, where highly selective and "green" processes are needed. Furthermore, the application of useful tests to discriminate between different oxygen activation routes, especially in the area of hydrocarbon oxidation, with the aim of an enhanced catalyst design, is described and discussed. In fact, one of the major targets of selective oxidation is the use of molecular oxygen as ultimate oxidant, combined with the development of catalysts capable to perform the catalytic cycle in a real energy and cost effective manner on a large scale. To achieve this goal, insights from metallo-proteins that could find application in some areas of industrial catalysis are presented, as well as considering the physicochemical principles that are at the fundament of oxidation and autoxidation processes.3

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“…Synthetic cryptomelane, known as octahedral molecular sieve (OMS-2), has been reported as an efficient catalyst in many oxidation reactions [4,5]. OMS-2 is a porous manganese oxide with a composition of KMn 8 O 16 and a structure consisting of 4.6Á × 4.6Á * Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

Enhanced catalytic degradation of ciprofloxacin over Ce-doped OMS-2 microspheres

Zhang

Lyu

2016

Applied Catalysis B: Environmental

127

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Cyclohexane oxidation catalyzed by manganese oxide octahedral molecular sieves—Effect of acidity of the catalyst

Cited by 149 publications

References 30 publications

Insights into the Reaction Mechanism of Cyclohexane Oxidation Catalysed by Molybdenum Blue Nanorings

Insights into the Reaction Mechanism of Cyclohexane Oxidation Catalysed by Molybdenum Blue Nanorings

Catalytic oxygen activation versus autoxidation for industrial applications: a physicochemical approach

Enhanced catalytic degradation of ciprofloxacin over Ce-doped OMS-2 microspheres

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