Oxidation of cyclohexane—A significant impact of stainless steel reactor wall

Hao, Jianmin; Cheng, Haiyang; Wang, Hongjun; Cai, Shengbao; Zhao, Fengyu

doi:10.1016/j.molcata.2007.02.031

Cited by 25 publications

(11 citation statements)

References 21 publications

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“…Blank experiments with unmodified silica, but without the Pd catalyst, were also examined, giving maximum conversions to cyclohexanol and cyclohexanone of 1.1 and 0.3%, respectively (under the same conditions of run 4, Table 1). This low conversions, although detectable, activity can result, at least in part, from the effect of the autoclave walls [19], but this was not investigated further, in the present study, in view of its low significance. The strong smell at the end of the reaction, when carried out in the presence of the Pd catalysts, indicated the product formation which was further confirmed by GC and GC-MS analyses that allow to quantify the amounts of KA oil as the main products and very little amount of acids formed as by product.…”

Section: Resultsmentioning

confidence: 73%

Oxidation of Cyclohexane with Molecular Oxygen Catalyzed by SiO2 Supported Palladium Catalysts

Mishra¹,

Sinha

2008

Catal Lett

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The di(ethylthio)ethane palladium (A) and di(ethylthio)propane palladium (B) complexes have been immobilized on the surface of silica gel and these catalyst systems are shown to serve as effective supported Pd catalysts for cyclohexane oxidation with O 2 under solvent free condition. The supported catalyst A provides best results (overall ca. 16.2% conversion, with a selectivity of 72 or 24% for cyclohexanol or cyclohexanone, respectively, which are further promoted in the presence of 2-pyrazinecarboxylic acid which acts as a co-catalyst (overall ca. 21.2% conversion).

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Section: Resultsmentioning

confidence: 73%

Oxidation of Cyclohexane with Molecular Oxygen Catalyzed by SiO2 Supported Palladium Catalysts

Mishra¹,

Sinha

2008

Catal Lett

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“…The particularly high surface-to-volume ratio in a micro structured reactor (the inner surface area of a 16 mL coil with an inner diameter of 1 mm is 640 cm 2 ) may entail pronounced reactor wall effects and unexpected/undesired side and degradative reactions [ 33 ]. The stainless steel reactor contains a variety of metals and the reactor walls could possibly act as heterogeneous catalysts (surface catalysis) [ 34 ]. Furthermore, the surface can potentially be considered as a metal oxide which usually forms surface hydroxyl groups in contact with water.…”

Section: Resultsmentioning

confidence: 99%

Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor

Gutmann¹,

Glasnov²,

Razzaq³

et al. 2011

Beilstein J. Org. Chem.

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SummaryThe decomposition of 5-benzhydryl-1H-tetrazole in an N-methyl-2-pyrrolidone/acetic acid/water mixture was investigated under a variety of high-temperature reaction conditions. Employing a sealed Pyrex glass vial and batch microwave conditions at 240 °C, the tetrazole is comparatively stable and complete decomposition to diphenylmethane requires more than 8 h. Similar kinetic data were obtained in conductively heated flow devices with either stainless steel or Hastelloy coils in the same temperature region. In contrast, in a flow instrument that utilizes direct electric resistance heating of the reactor coil, tetrazole decomposition was dramatically accelerated with rate constants increased by two orders of magnitude. When 5-benzhydryl-1H-tetrazole was exposed to 220 °C in this type of flow reactor, decomposition to diphenylmethane was complete within 10 min. The mechanism and kinetic parameters of tetrazole decomposition under a variety of reaction conditions were investigated. A number of possible explanations for these highly unusual rate accelerations are presented. In addition, general aspects of reactor degradation, corrosion and contamination effects of importance to continuous flow chemistry are discussed.

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“…steel reactors can initiate radical formation. 152,153 Kinetic explosions can take place where radicals are uncontrollably formed. Termination of the radical chain reaction can typically occur at the reactor surface.…”

Section: Safety Aspectsmentioning

confidence: 99%

Beyond Organometallic Flow Chemistry: The Principles Behind the Use of Continuous-Flow Reactors for Synthesis

Noël

Hessel

2015

Topics in Organometallic Chemistry

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Flow chemistry is typically used to enable challenging reactions which are difficult to carry out in conventional batch equipment. Consequently, the use of continuous-flow reactors for applications in organometallic and organic chemistry has witnessed a spectacular increase in interest from the chemistry community in the last decade. However, flow chemistry is more than just pumping reagents through a capillary and the engineering behind the observed phenomena can help to exploit the technology's full potential. Here, we give an overview of the most important engineering aspects associated with flow chemistry. This includes a discussion of mass-, heat-, and photon-transport phenomena which are relevant to carry out chemical reactions in a microreactor. Next, determination of intrinsic kinetics, automation of chemical processes, solids handling and multistep reaction sequences in flow are discussed. Safety is one of the main drivers to implement continuous-flow microreactor technology in an existing process and a brief overview is given here as well. Finally, the scale-up potential of microreactor technology is reviewed.

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Oxidation of cyclohexane—A significant impact of stainless steel reactor wall

Cited by 25 publications

References 21 publications

Oxidation of Cyclohexane with Molecular Oxygen Catalyzed by SiO2 Supported Palladium Catalysts

Oxidation of Cyclohexane with Molecular Oxygen Catalyzed by SiO2 Supported Palladium Catalysts

Unusual behavior in the reactivity of 5-substituted-1H-tetrazoles in a resistively heated microreactor

Beyond Organometallic Flow Chemistry: The Principles Behind the Use of Continuous-Flow Reactors for Synthesis

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