Aerobic oxidation of cyclohexane by gold-based catalysts: New mechanistic insight by thorough product analysis

Hereijgers, Bart P. C.; Weckhuysen, Bert M.

doi:10.1016/j.jcat.2009.12.003

Cited by 167 publications

(125 citation statements)

References 43 publications

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“…179,186 The total selectivities for KA oil were very high and nearly constant regardless of the conversion; the selectivities were as high as µ99% for smaller 0.2Au n /HAP (n = 1039), whereas the selectivity was slightly smaller (µ95%) for 0.2Au µ85 /HAP. This is in sharp contrast to the previously reported trade-off relationship between conversion and selectivity 181,185 Figure 21 shows a plot of the TOF values (defined as the number of cyclohexane converted per Au atom in the cluster per hour) as a function of cluster size n. The TOF values increase monotonically with increasing size in the range n = 10 to 39, but decrease in the range n = 39 to µ85.…”

Section: Catalysis For Aerobic Oxidation Of Cyclohexanementioning

confidence: 99%

Toward an Atomic-Level Understanding of Size-Specific Properties of Protected and Stabilized Gold Clusters

Tsukuda

2012

Bulletin of the Chemical Society of Japan

232

230

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Metal clusters consisting of fewer than 100 atoms (diameter <2 nm) are highly promising as a new class of building units for functional materials because of their novel and size-dependent properties. Nevertheless, basic and applied studies of metals clusters have been hampered by the lack of specific guidelines for design and precise synthetic methods. This account surveys recent investigations of gold clusters focusing on our effort toward an atomic-level understanding and control of their size-specific properties. We have developed a size-controlled method for synthesizing gold clusters protected by ligands, stabilized by polymers, and supported on solids. Remarkable size-effects on stabilities and various properties including catalysis were observed. Their mechanisms are discussed based on fundamental knowledge of bare gold clusters in the gas phase.

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Section: Catalysis For Aerobic Oxidation Of Cyclohexanementioning

confidence: 99%

Toward an Atomic-Level Understanding of Size-Specific Properties of Protected and Stabilized Gold Clusters

Tsukuda

2012

Bulletin of the Chemical Society of Japan

232

230

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“…The cumulative effect of all these aspects shows the complexity of autoxidation reactions, along with any oxidation reaction that produces alkyl peroxides or alkyl hydroperoxide species during the process, as this will result in a parallel autoxidation pathway that can mask the actual catalytic efficiency of a system. 148,154,155 …”

Section: Characterization Of the Reaction Products In Autoxidation Prmentioning

confidence: 99%

“…202 In contrast the use of metal nanoparticle based systems like Au/MgO or Au/ZSM-5 in liquid phase, showed an enhancement of the autoxidation pathway only, thus suggesting that the metal in this case is actually a promoter. 148,154 To date one of the most complete schemes in the propagation reaction of the alkyl peroxide radical is the one obtained by Jacobs and coworkers (Scheme 9) It also considers the formation of ring opening products like formyl species 165 thus showing the variety of combinations that reactions just involving ground state triplet oxygen can achieve when compared to pure catalytic processes involving heterolytic oxygen activation. Scheme 9.…”

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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“…However, some gold catalysts supported on MSM have been synthesized using this approach, as summarized in Table 5. For example, Hereijgers and Weckhuysen [173] prepared Au/SBA-15 by DP from a dilute solution of HAuCl 4 in HCl at pH of 9.5 using ammonia solution. After calcination, AuNPs with average value of 4.0 nm were obtained, but the structure of the SBA-15 support was slightly damaged because of the high pH effect.…”

Section: Deposition-precipitationmentioning

confidence: 99%

Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments

2011

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Mesoporous silica materials (MSM) with ordered and controllable porous structure, high surface area, pore volume and thermal stability are very suitable catalyst supports, because they provide high dispersion of metal nanoparticles and facilitate the access of the substrates to the active sites. Since the conventional wet-impregnation and deposition-precipitation methods are not appropriate for the incorporation of gold nanoparticles (AuNPs) into MSM, considerable efforts have been made to develop suitable methods to synthesize Au/MSM catalysts, because the incorporation of AuNPs into the channel system can prevent their agglomeration and leaching. In this review, we summarize the main methods to synthesize active gold catalysts supported on MSM. Examples and details of the preparative methods, as well as selected applications are provided. We expect this article to be interesting to researchers due to the wide variety of chemical reactions that can be catalyzed by gold supported catalysts.

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Aerobic oxidation of cyclohexane by gold-based catalysts: New mechanistic insight by thorough product analysis

Cited by 167 publications

References 43 publications

Toward an Atomic-Level Understanding of Size-Specific Properties of Protected and Stabilized Gold Clusters

Toward an Atomic-Level Understanding of Size-Specific Properties of Protected and Stabilized Gold Clusters

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

Synthesis of Gold Catalysts Supported on Mesoporous Silica Materials: Recent Developments

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