Aerobic oxidation of 4-tert-butyltoluene over cobalt and manganese supported hexagonal mesoporous silicas as heterogeneous catalysts

Yu, Wei; Zhou, Chun Hui; Tong, Dong Shen; Xu, Tian

doi:10.1016/j.molcata.2012.09.004

Cited by 30 publications

(4 citation statements)

References 46 publications

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“…The origins of the observed redox peaks were assigned on the basis of the peak characteristics and results of previous studies. Mn(III) in Mn 3 O 4 nanoparticles reportedly exhibits O 2– → Mn II (210–250 nm) and O 2– → Mn III (350–390 nm) charge transfer transitions and d–d crystal field transitions in the range of 550–700 nm. − In contrast, Mn(IV) species in MnO 2 exhibit a broad peak in the region of 400 nm and shoulder peaks at approximately 575 and 700 nm . The in situ UV–vis spectral changes for the MnO NPs, in which a continuous peak between 350 and 500 nm and a broad shoulder between 500 and 700 nm were observed, are nearly identical to those previously reported for Mn(IV) species in MnO 2 nanocrystals. , Although no distinct peak was observed for Mn(V), we could not exclude the formation of Mn(V) species during catalysis.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic Investigation of Water Oxidation Catalyzed by Uniform, Assembled MnO Nanoparticles

et al. 2017

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The development of active water oxidation catalysts is critical to achieve high efficiency in overall water splitting. Recently, sub-10 nm-sized monodispersed partially oxidized manganese oxide nanoparticles were shown to exhibit not only superior catalytic performance for oxygen evolution, but also unique electrokinetics, as compared to their bulk counterparts. In the present work, the water-oxidizing mechanism of partially oxidized MnO nanoparticles was investigated using integrated in situ spectroscopic and electrokinetic analyses. We successfully demonstrated that, in contrast to previously reported manganese (Mn)-based catalysts, Mn(III) species are stably generated on the surface of MnO nanoparticles via a proton-coupled electron transfer pathway. Furthermore, we confirmed as to MnO nanoparticles that the one-electron oxidation step from Mn(II) to Mn(III) is no longer the rate-determining step for water oxidation and that Mn(IV)═O species are generated as reaction intermediates during catalysis.

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Section: Resultsmentioning

confidence: 99%

Mechanistic Investigation of Water Oxidation Catalyzed by Uniform, Assembled MnO Nanoparticles

et al. 2017

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“…Moreover, it has several features, such as being highly active, stable, inexpensive, and ecofriendly catalyst [51][52][53][54][55][56]. However, different types of manganese oxide, mixed manganese oxide, and noble metal doped/supported Mn oxides were widely employed for the catalytic oxidation of numerous organic substrates, for instance, oxidation of naphthalene to carbon dioxide [57], oxidation of carbon monoxide to CO 2 [58,59], oxidation of toluene to CO 2 [60], oxidation of ethylene and propylene to CO 2 [61], oxidation of cyclohexane to cyclohexanol and cyclohexanone [62], oxidation of alkyl aromatics to ketones [63], oxidation of 4-tert-butyltoluene to 4-tert-butylbenzaldehyde [64], and oxidation of formaldehyde to CO 2 [65].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO₃, –MnO₂, and –Mn₂O₃ Nanocomposites for Aerial Oxidation of Alcohols

Assal

Kuniyil

Shaik

et al. 2017

Journal of Chemistry

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Zinc oxide nanoparticles doped manganese carbonate catalysts [ % ZnO x -MnCO 3 ] (where = 0-7) were prepared via a facile and straightforward coprecipitation procedure, which upon different calcination treatments yields different manganese oxides, that is, [ % ZnO x -MnO 2 ] and [ % ZnO x -Mn 2 O 3 ]. A comparative catalytic study was conducted to evaluate the catalytic efficiency between carbonates and oxides for the selective oxidation of secondary alcohols to corresponding ketones using molecular oxygen as a green oxidizing agent without using any additives or bases. The prepared catalysts were characterized by different techniques such as SEM, EDX, XRD, TEM, TGA, BET, and FTIR spectroscopy. The 1% ZnO x -MnCO 3 calcined at 300 ∘ C exhibited the best catalytic performance and possessed highest surface area, suggesting that the calcination temperature and surface area play a significant role in the alcohol oxidation. The 1% ZnO x -MnCO 3 catalyst exhibited superior catalytic performance and selectivity in the aerial oxidation of 1-phenylethanol, where 100% alcohol conversion and more than 99% product selectivity were obtained in only 5 min with superior specific activity (48 mmol⋅g −1 ⋅h −1 ) and 390.6 turnover frequency (TOF). The specific activity obtained is the highest so far (to the best of our knowledge) compared to the catalysts already reported in the literatures used for the oxidation of 1-phenylethanol. It was found that ZnO x nanoparticles play an essential role in enhancing the catalytic efficiency for the selective oxidation of alcohols. The scope of the oxidation process is extended to different types of alcohols. A variety of primary, benzylic, aliphatic, allylic, and heteroaromatic alcohols were selectively oxidized into their corresponding carbonyls with 100% convertibility without overoxidation to the carboxylic acids under base-free conditions.

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“…Examples of heterogeneous NHPI catalysts include NHPI immobilized on silica gel by physical interaction [19], NHPI immobilized by chemical bonds on silica gel [20,21], polystyrene [22], copolymer microspheres of glycidyl and methyl methacrylate (GMA/MMA) [23] or glycidoxypropyl-SBA-15 [24] and NHPI incorporated into metal organic framework [25][26][27][28][29]. On the other hand, silica supported cobalt(II) [30,31], cobalt and manganese supported hexagonal mesoporous silicas [32] or cobalt Shiff base complex anchored on starch-coated magnetic nanoparticles [33] were also examined in the presence of homogeneous NHPI. The activity of these catalytic systems was demonstrated in aerobic oxidations of cyclohexane and other cyclic hydrocarbons [19,25,[27][28][29]32], toluenes [20][21][22]24], ethylbenzenes [23,25,30,31,33], styrenes [26] as well as other alkyl aromatic compounds [29,31,33] and benzylic alcohols [33].…”

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confidence: 99%

“…On the other hand, silica supported cobalt(II) [30,31], cobalt and manganese supported hexagonal mesoporous silicas [32] or cobalt Shiff base complex anchored on starch-coated magnetic nanoparticles [33] were also examined in the presence of homogeneous NHPI. The activity of these catalytic systems was demonstrated in aerobic oxidations of cyclohexane and other cyclic hydrocarbons [19,25,[27][28][29]32], toluenes [20][21][22]24], ethylbenzenes [23,25,30,31,33], styrenes [26] as well as other alkyl aromatic compounds [29,31,33] and benzylic alcohols [33]. For example, when toluene was oxidized with oxygen in the presence of both NHPI and Co(II) chemically bonded to silica gel in AcOH as solvent, conversion of 18 % was achieved (100 °C, 0.1 MPa, 20 h) [20].…”

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confidence: 99%

N-Hydroxyphthalimide Immobilized on Poly(HEA-co-DVB) as Catalyst for Aerobic Oxidation Processes

et al. 2016

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was tested in aerobic oxidation of p-methoxytoluene and α-methylstyrene. The studied reactions were carried out in the presence of AIBN and/or Co(II) salt without solvent or in acetic acid as solvent. It was found that the obtained polymer-supported NHPI catalyst showed the best catalytic performance, which was attributed to a high content of accessible NHPI moieties. The recovery and recycling of the obtained HEA/DVB-NHPI was only possible in reactions proceeded in solvent-free conditions. Abstract In the present study, poly(HEA-co-DVB) was synthesized (loading of OH groups: 8.07 mmol OH/g, crosslinking degree: 6 % DVB) and used for N-hydroxyphthalimide (NHPI) immobilization via ester bond (NHPI loading: 2.06 mmol NHPI/g). The obtained polymeric support and poly(HEA-co-DVB)/NHPI catalyst were characterized by FT-IR and XPS spectroscopy, elemental analysis, thermogravimetry and particle size measurement. The novel polymer-supported NHPI catalyst 1 3

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Aerobic oxidation of 4-tert-butyltoluene over cobalt and manganese supported hexagonal mesoporous silicas as heterogeneous catalysts

Cited by 30 publications

References 46 publications

Mechanistic Investigation of Water Oxidation Catalyzed by Uniform, Assembled MnO Nanoparticles

Mechanistic Investigation of Water Oxidation Catalyzed by Uniform, Assembled MnO Nanoparticles

Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO₃, –MnO₂, and –Mn₂O₃ Nanocomposites for Aerial Oxidation of Alcohols

N-Hydroxyphthalimide Immobilized on Poly(HEA-co-DVB) as Catalyst for Aerobic Oxidation Processes

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Aerobic oxidation of 4-tert-butyltoluene over cobalt and manganese supported hexagonal mesoporous silicas as heterogeneous catalysts

Cited by 30 publications

References 46 publications

Mechanistic Investigation of Water Oxidation Catalyzed by Uniform, Assembled MnO Nanoparticles

Mechanistic Investigation of Water Oxidation Catalyzed by Uniform, Assembled MnO Nanoparticles

Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO3, –MnO2, and –Mn2O3 Nanocomposites for Aerial Oxidation of Alcohols

N-Hydroxyphthalimide Immobilized on Poly(HEA-co-DVB) as Catalyst for Aerobic Oxidation Processes

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Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO₃, –MnO₂, and –Mn₂O₃ Nanocomposites for Aerial Oxidation of Alcohols