Detection and Measurement of Surface Electron Transfer on Reduced Molybdenum Oxides (MoOx) and Catalytic Activities of Au/MoOx

Wang, Feng; Ueda, Wataru; Xu, Jie

doi:10.1002/ange.201105922

Cited by 15 publications

(6 citation statements)

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“…It is reported that the presence of negative charge on the Au core would enhance the catalytic activity of Au for aerobic oxidations. [64][65][66] Recent theoretical calculations also confirm that this interaction can increase the reaction activity. [67] Therefore, we conclude that these strong interactions transfer the charge to the Au cluster and lead to the high performance of the reaction (Scheme 1 B), besides protecting the gold nanoclusters against sintering.…”

Section: Resultsmentioning

confidence: 83%

“…This charge transfer makes the gold cluster more electronegative, which facilitate the HMF oxidation. It is reported that the presence of negative charge on the Au core would enhance the catalytic activity of Au for aerobic oxidations 64–66. Recent theoretical calculations also confirm that this interaction can increase the reaction activity 67.…”

Section: Resultsmentioning

confidence: 93%

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Gold Nanoclusters Confined in a Supercage of Y Zeolite for Aerobic Oxidation of HMF under Mild Conditions

Cai

Zhang

et al. 2013

Chemistry A European J

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192

104

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Au nanoclusters with an average size of approximately 1 nm size supported on HY zeolite exhibit a superior catalytic performance for the selective oxidation of 5‐hydroxymethyl‐2‐furfural (HMF) into 2,5‐furandicarboxylic acid (FDCA). It achieved >99 % yield of 2,5‐furandicarboxylic acid in water under mild conditions (60 °C, 0.3 MPa oxygen), which is much higher than that of Au supported on metal oxides/hydroxide (TiO2, CeO2, and Mg(OH)2) and channel‐type zeolites (ZSM‐5 and H‐MOR). Detailed characterizations, such as X‐ray diffraction, transmission electron microscopy, N2‐physisorption, and H2‐temperature‐programmed reduction (TPR), revealed that the Au nanoclusters are well encapsulated in the HY zeolite supercage, which is considered to restrict and avoid further growing of the Au nanoclusters into large particles. The acidic hydroxyl groups of the supercage were proven to be responsible for the formation and stabilization of the gold nanoclusters. Moreover, the interaction between the hydroxyl groups in the supercage and the Au nanoclusters leads to electronic modification of the Au nanoparticles, which is supposed to contribute to the high efficiency in the catalytic oxidation of HMF to FDCA.

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Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 93%

Gold Nanoclusters Confined in a Supercage of Y Zeolite for Aerobic Oxidation of HMF under Mild Conditions

Cai

Zhang

et al. 2013

Chemistry A European J

Self Cite

192

104

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“…Wang et al have used a supported Au/MoO x heterogeneous catalyst for the aerobic oxidation of alcohols to aldehydes in high yields (eq 26). 28 In their study, the authors confirmed that electron transfer from the partially reduced MoO x support to the Au NPs would result in negatively charged Au cores, yielding highly active catalysts for the selective aerobic oxidation of alcohols. In a related earlier study, Au clusters smaller than 1.5 nm stabilized by poly(Nvinyl-2-pyrrolidinone) (PVP) were used as active catalysts for the aerobic oxidation of alcohol to aldehyde (eq 27).…”

Section: Semiconductor-metal Nanocompositesmentioning

confidence: 86%

“…Wang et al have used a supported Au/MoO x heterogeneous catalyst for the aerobic oxidation of alcohols to aldehydes in high yields (eq ) . In their study, the authors confirmed that electron transfer from the partially reduced MoO x support to the Au NPs would result in negatively charged Au cores, yielding highly active catalysts for the selective aerobic oxidation of alcohols.…”

Section: Semiconductor-metal Nanocompositesmentioning

confidence: 91%

Nanostructured Catalysts for Organic Transformations

2013

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The development of green, sustainable and economical chemical processes is one of the major challenges in chemistry. Besides the traditional need for efficient and selective catalytic reactions that will transform raw materials into valuable chemicals, pharmaceuticals and fuels, green chemistry also strives for waste reduction, atomic efficiency and high rates of catalyst recovery. Nanostructured materials are attractive candidates as heterogeneous catalysts for various organic transformations, especially because they meet the goals of green chemistry. Researchers have made significant advances in the synthesis of well-defined nanostructured materials in recent years. Among these are novel approaches that have permitted the rational design and synthesis of highly active and selective nanostructured catalysts by controlling the structure and composition of the active nanoparticles (NPs) and by manipulating the interaction between the catalytically active NP species and their support. The ease of isolation and separation of the heterogeneous catalysts from the desired organic product and the recovery and reuse of these NPs further enhance their attractiveness as green and sustainable catalysts. This Account reviews recent advances in the use of nanostructured materials for catalytic organic transformations. We present a broad overview of nanostructured catalysts used in different types of organic transformations including chemoselective oxidations and reductions, asymmetric hydrogenations, coupling reactions, C-H activations, oxidative aminations, domino and tandem reactions, and more. We focus on recent research efforts towards the development of the following nanostructured materials: (i) nanostructured catalysts with controlled morphologies, (ii) magnetic nanocomposites, (iii) semiconductor-metal nanocomposites, and (iv) hybrid nanostructured catalysts. Selected examples showcase principles of nanoparticle design such as the enhancement of reactivity, selectivity and/or recyclability of the nanostructured catalysts via control of the structure, composition of the catalytically active NPs, and/or nature of the support. These principles will aid researchers in the rational design and engineering of new types of multifunctional nanocatalysts for the achievement of green and sustainable chemical processes. Although the past decade has brought many advances, there are still challenges in the area of nanocatalysis that need to be addressed. These include loss of catalytic activity during operation due to sintering, leaching of soluble species from the nanocatalysts under harsh reaction conditions, loss of control over well-defined morphologies during the scale-up synthesis of the nanocomposites, and limited examples of enantioselective nanocatalytic systems. The future of nanocatalyst research lies in the judicious design and development of nanocomposite catalysts that are stable and resistant to sintering and leaching, and yet are highly active and enantioselective for the desired catalytic organic transformations, e...

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“…In this way, the conversion of transesterification (X b ) was obtained from GC injection of the extracted product, and a linear relationship was provided between À ln(1-X b ) and the reaction time in agreement with the literature. [35,36] Also, the kinetics was obtained for normal MeOH (Figure 2a).…”

Section: Catalyst Activitymentioning

confidence: 90%

Metal‐ and Solvent‐Free Transesterification and Aldol Condensation Reactions by a Homogenous Recyclable Basic Ionic Liquid Based on the 1,3,5‐Triazine Framework

Ren

Kazemnejadi

2021

ChemistryOpen

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A new recyclable basic ionic liquid was introduced as an efficient catalyst for aldol condensation and transesterification reactions under environmentally friendly conditions. The catalyst was prepared based on methyl imidazolium moieties bearing hydroxide counter anions via the Hofmann elimination on a 1,3,5‐triazine framework. The ionic liquid with two functionalities including anion stabilizer and high basicity, was used as an efficient catalyst for aldol condensation as well as transesterification reaction of a variety of alkyl benzoates. All reactions were performed in the absence of any external reagent, co‐catalyst, or solvent, in line with environmental protection. The kinetics isotope effect (KIE) was conducted for the transesterification reaction to elucidate the mechanism and rate determining step (RDS). It worth noted that, the homogeneous catalyst could be recycled from the reaction mixture and reused for several consecutive runs with insignificant drop of basicity and conversion.

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Detection and Measurement of Surface Electron Transfer on Reduced Molybdenum Oxides (MoO_x) and Catalytic Activities of Au/MoO_x

Cited by 15 publications

References 50 publications

Gold Nanoclusters Confined in a Supercage of Y Zeolite for Aerobic Oxidation of HMF under Mild Conditions

Gold Nanoclusters Confined in a Supercage of Y Zeolite for Aerobic Oxidation of HMF under Mild Conditions

Nanostructured Catalysts for Organic Transformations

Metal‐ and Solvent‐Free Transesterification and Aldol Condensation Reactions by a Homogenous Recyclable Basic Ionic Liquid Based on the 1,3,5‐Triazine Framework

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