Graham J. Hutchings

Cardiff University, Cardiff, Wales, United Kingdom

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Publications (629)2354.32 Total impact

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    ABSTRACT: Glycerol is an important byproduct of biodiesel production, and it is produced in significant amounts by transesterification of triglycerides with methanol. Due to the highly functionalized nature of glycerol, it is an important biochemical that can be utilized as a platform chemical for the production of high-added-value products. At present, research groups in academia and industry are exploring potential direct processes for the synthesis of useful potential chemicals using catalytic processes. Over the last 10 years, there has been huge development of potential catalytic processes using glycerol as the platform chemical. One of the most common processes investigated so far is the catalytic oxidation of glycerol at mild conditions for the formation of valuable oxygenated compounds used in the chemical and pharmaceutical industry. The major challenges associated with the selective oxidation of glycerol are (i) the control of selectivity to the desired products, (ii) high activity and resistance to poisoning, and (iii) minimizing the usage of alkaline conditions. To address these challenges, the most common catalysts used for the oxidation of glycerol are based on supported metal nanoparticles. The first significant breakthrough was the successful utilization of supported gold nanoparticles for improving the selectivity to specific products, and the second was the utilization of supported bimetallic nanoparticles based on gold, palladium, and platinum for improving activity and controlling the selectivity to the desired products. Moreover, the utilization of base-free reaction conditions for the catalytic oxidation of glycerol has unlocked new pathways for the production of free-base products, which facilitates potential industrial application. The advantages of using gold-based catalysts are the improvement of the catalyst lifetime, stability, and reusability, which are key factors for potential commercialization. In this Account, we discuss the advantages of the using supported gold-based nanoparticles, preparation methods for achieving highly active gold-based catalysts, and parameters such as particle size, morphology of the bimetallic particle, and metal-support interactions, which can influence activity and selectivity to the desired products.
    Accounts of Chemical Research 04/2015; DOI:10.1021/ar500426g · 24.35 Impact Factor
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    ABSTRACT: The selective oxidation of linear alkanes with molecular oxygen under mild conditions remains a challenging topic in the field of catalysis. In this study we investigate the co-oxidation of C-H bonds in substrates with different relative reactivities, the aim being to couple the oxidised products in situ to form the corresponding esters. Initial attempts were made to co-oxidise octane with toluene to form octyl benzoate using Au-Pd catalysts. During the study the oxidation of octane in the presence of benzaldehyde, an oxidation product of toluene, was also investigated in order to demonstrate the potential feasibility of the reaction. This work summarises our attempts to show whether a co-oxidation system could be an effective way to oxidise linear alkanes.
    04/2015; DOI:10.1039/C5CY00453E
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    ABSTRACT: A detailed study of the selective oxidation of cyclohexane has been performed using bimetallic gold-palladium catalysts supported on magnesium oxide. Mono-metallic supported gold or palladium catalysts show limited activity for cyclohexane oxidation. However, a significantly enhanced catalytic performance is observed when supported gold-palladium alloy catalysts are used for this particular reaction. This synergy is observed for alloys spanning a wide range of gold-to-palladium molar ratios. Mechanistic studies reveal a promotion effect that occurs from alloying palladium with gold on the supported catalyst, which significantly improves the homo-cleavage of the O-O bond in cyclohexyl hydroperoxide, an important intermediate species in cyclohexane oxidation.
  • ChemInform 03/2015; 46(13). DOI:10.1002/chin.201513317
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    ABSTRACT: A Teflon AF-2400 tube-in-tube microreactor is investigated for the continuous, solvent-free, catalytic oxidation of benzyl alcohol with oxygen. The semipermeable Teflon AF-2400 tube acts as the interface between the gaseous oxidant and the liquid substrate. Because of the inherent safety of this contacting method, the use of pure oxygen is possible. The semipermeable tube was packed with 1 wt % Au-Pd/TiO2 catalyst particles and placed inside a PTFE tube to provide an annular region which was pressurized with pure oxygen. This design allowed continuous penetration of oxygen through the inner tube during the reaction, resulting in higher oxygen concentration in the catalyst bed and significantly improved conversion compared to a reactor operating with an oxygen presaturated feed. The amount of oxygen available for reaction in the tube-in-tube microreactor was 2 orders of magnitude higher than that in a nonpermeable reactor with oxygen presaturated feed. The semipermeable tube reactor performance in terms of both conversion and selectivity was enhanced by increasing the gas pressure, the catalyst contact time and by dilution of the catalyst. The highest conversion of benzyl alcohol obtained for the range of conditions investigated was 44.1%, with 73.0% selectivity to benzaldehyde, at 120 °C; catalyst contact time, 115 gcat·s/galcohol; and catalyst dilution factor, 4.
    Industrial & Engineering Chemistry Research 02/2015; DOI:10.1021/ie5041176 · 2.24 Impact Factor
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    ABSTRACT: Recent advances in the oxidation of alcohols to methyl esters using metal nanoparticles have paved the way for more environmentally benign processes, operating at lower reaction temperatures with high product selectivity. Here, we demonstrate the use of bimetallic 1 wt % Au-Pd/TiO2 catalysts that achieve high activity for the oxidation of methanol to methyl formate at low temperature. The application of a water extraction treatment to retain size-stabilized Au-Pd nanoparticles, in contrast to a more standard thermal treatment, provides the most active catalyst for this reaction. Using in situ DRIFTS, we demonstrate that in situ activation during methanol oxidation enhances the catalytic activity at low temperature and that this is a long-lived effect. Surface adsorbates, particularly formate species, build up on the catalyst surface during the reaction and are proven vital to enhancing the catalytic effect.Keywords: methanol; methyl formate; oxidation; gold−palladium; nanoparticles; active species
    ACS Catalysis 01/2015; 5(2):637. DOI:10.1021/cs501728r · 7.57 Impact Factor
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    ABSTRACT: Ruthenium-ion-catalyzed oxidation of a range of alkylated polyaromatics has been studied. 2-Ethylnaphthalene was used as a model substrate, and oxidation can be performed in either a conventional biphasic or in a monophasic solvent system. In either case the reaction rates and product selectivity are identical. The reaction products indicate that the aromatic ring system is oxidized in preference to the alkyl chain. This analysis is possible due to the development of a quantitative NMR protocol to determine the relative amounts of aliphatic and aromatic protons. From a systematic set of substrates we show that as the length of the alkyl chain substituent on a polyaromatic increases, the proportion of products in which the chain remains attached to the aromatic system increases. Larger polyaromatic systems, based on pyrene and phenanthrene, show greater reactivity than those with fewer aromatic rings, and the alkyl chains are more stable to oxidation.
    Chemistry - A European Journal 01/2015; 21(11). DOI:10.1002/chem.201405831 · 5.70 Impact Factor
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    ABSTRACT: The base-free selective catalytic oxidation of n-butanol by O2 in an aqueous phase has been studied using Au-Pd bimetallic nanoparticles supported on titania. Au-Pd/TiO2 catalysts were prepared by different methods: wet impregnation, physical mixing, deposition–precipitation and sol immobilisation. The sol immobilisation technique, which used polyvinyl alcohol (PVA) as the stabilizing agent, gave the catalyst with the smallest average particle size and the highest stable activity and selectivity towards butyric acid. Increasing the amount of PVA resulted in a decrease in the size of the nanoparticles. However, it also reduced activity by limiting the accessibility of reactants to the active sites. Heating the catalyst to reflux with water at 90 °C for 1 h was the best method to enhance the surface exposure of the nanoparticles without affecting their size, as determined by TEM, X-ray photoelectron spectroscopy and CO chemisorption analysis. This catalyst was not only active and selective towards butyric acid but was also stable under the operating conditions.
    ChemSusChem 12/2014; 8(3). DOI:10.1002/cssc.201403190 · 7.12 Impact Factor
  • Graham J. Hutchings
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    ABSTRACT: Supported gold nanoparticles are highly effective for a range of redox reactions. In these reactions the activity is often enhanced by the addition of a second or indeed a third metallic component. A model reaction that is often investigated is the selective oxidation of benzyl alcohol using molecular oxygen as terminal oxidant. In the presence of a solvent the complexity of this reaction can often be missed. However, in the solvent-free oxidation of benzyl alcohol to benzaldehyde using supported gold palladium nanoparticles as catalysts, there are two pathways to the principal product, benzaldehyde. One is the direct catalytic oxidation of benzyl alcohol to benzaldehyde by O-2, while the second is the disproportionation of two molecules of benzyl alcohol to give equal amounts of benzaldehyde and toluene. The formation of toluene is an unwanted side reaction. In this paper the research on this reaction will be reviewed and two strategies described that can be used to switch off the formation of the non desired toluene. The first involves the use of basic supports for the gold palladium nanoparticles, which is highly effective in suppressing the formation of toluene and this may be related to the morphology of the gold palladium nanoparticles and their interaction with the support. The second involves the introduction of platinum to the gold palladium nanoparticles which also switches off toluene formation on supports that permit toluene formation in the absence of platinum. This effect may be related to the relative stability of platinum hydride.
    Catalysis Today 12/2014; 238:69–73. DOI:10.1016/j.cattod.2014.01.033 · 3.31 Impact Factor
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    ABSTRACT: The discovery of novel m aterials that can be active, selective and stable catalysts for the efficient transformation of organic molecules to useful products is of high importance. In recent years, there has been significant interest in the utilisation of supported gold-based nanoparticles that can be effective catalysts for a broad range of chemical processes. In this paper, we describe and discuss the utilisation of gold-based nanoparticles as efficient catalysts for a range of important reactions, with particular emphasis placed on our team recent research.
    ChemInform 11/2014; 45(47). DOI:10.1002/chin.201447286
  • Organic Process Research & Development 11/2014; 18(11):1455-1460. DOI:10.1021/op500195e · 2.55 Impact Factor
  • Graham J. Hutchings
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    ABSTRACT: catalysts for a broad range of reactions. Most notably, for reactions such as the hydrochlorination of acetylene and the oxidation of carbon monoxide supported gold nanoparticles show exceptionally high activity. In this paper some of the discussion points raised at the Irsee VI Symposium held in July 2013 will be presented. The preparation of active supported gold nanoparticles will be described for the hydrochlorination of acetylene and the oxidation of carbon monoxide.
    ChemInform 11/2014; 45(46). DOI:10.1002/chin.201446269
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    ABSTRACT: Abstracts: * 2014 AIChE Annual Meeting20023 Catalysis with Microporous and Mesoporous.docx (15.7KB) - Uploading Abstracts
    14 AIChE Annual Meeting; 11/2014
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    ABSTRACT: The oxidation of dec-1-ene is investigated under solvent-free conditions using gold nanoparticles supported on graphite and in a batch reactor in the presence of a radical initiator using oxygen from air as the terminal oxidant. The evolution of the products with reaction time shows that there is an initial induction period and during this time very little epoxide is fomed and the products of allylic oxidation are dominant. Subsequently the epoxide becomes the major product prior to the diol being formed from hydrolysis due to the presence of by-product water formed from the selective oxidation reaction. It is considered that the allylic oxidation products are in part converted in situ into aldehydes which form peracids during the induction period; the peracid leads to epoxide formation as the major product as the conversion is increased. The effect of addition of a number of aldehydes is investigated, all leading to enhanced epoxide formation when added in small amounts. Molar enhancements of epoxide yield can approach twice the amount of aldehyde initially added. This behaviour is in contrast to earlier studies which utilise aldehydes in greater than stoichiometric amounts as sacrificial reactants. The importance of in situ aldehyde formation is also demonstrated by the addition of benzyl alcohol which under the reaction conditions rapidly gives benzaldehyde and enhanced epoxide formation. Possible mechanistic interpretations of the observations are discussed.
    11/2014; 5(2). DOI:10.1039/C4CY01355G
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    ABSTRACT: The development of efficient photocatalytic routines for producing hydrogen is of great importance as society moves away from energy sources derived from fossil fuels. Recent studies have identified that the addition of metal nanoparticles to TiO2 greatly enhances the photocatalytic performance of these materials towards the reforming of alcohols for hydrogen production. The core-shell structured Au-Pd bimetallic nanoparticle supported on TiO2 has being of interest as it exhibited extremely high quantum efficiencies for hydrogen production. However, the effect of shell composition and thickness on photocatalytic performance remains unclear. Here we report the synthesis of core-shell structured AuPd NPs with the controlled deposition of one and two monolayers (ML) equivalent of Pd onto Au NPs by colloidal and photodeposition methods. We have determined the shell composition and thickness of the nanoparticles by a combination of X-ray absorption fine structure and X-ray photoelectron spectroscopy. Photocatalytic ethanol reforming showed that the core-shell structured Au-Pd promoters supported on TiO2 exhibit enhanced activity compared to that of monometallic Au and Pd as promoters, whilst the core-shell Au-Pd promoters containing one ML equivalent Pd provide the optimum reactivity.
    Physical Chemistry Chemical Physics 11/2014; 16(48). DOI:10.1039/c4cp04693e · 4.20 Impact Factor
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    ABSTRACT: We studied the reactivity of 1,6-enynes with thioacetic acid (AcSH) under either thermal conditions or in the presence of catalytic amounts of supported Au or Au–Pd nanoparticles (NPs) under mild conditions. The 1,6-enynes undergo a tandem thioacylation/cyclization to original cyclic products featuring either a homoallylic thioester function or an enol thioester function depending on the substrate topology. Interestingly, the former process was found more efficient when performed in the presence of Au–Pd NPs while the latter process can be efficiently carried out under thermal conditions (100 °C). The reaction proceeds by a radical mechanism and the presence of precious metal NPs seems to stabilize the formation of free radical intermediates, as supported by experimental and theoretical results.
    Tetrahedron 11/2014; 46(16). DOI:10.1016/j.tet.2014.10.077 · 2.82 Impact Factor
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    ABSTRACT: As co-catalyst materials, metal nanoparticles (NPs) play crucial roles in heterogeneous photocatalysis. The photocatalytic performance strongly relies on the physical properties (i.e., composition, microstructure, and surface impurities) of the metal NPs. Here we report a convenient chemical vapour impregnation (CVI) approach for the deposition of monometallic-, alloyed, and core-shell structured metal co-catalysts onto the TiO2 photocatalyst. The as-synthesised metal NPs are highly dispersed on the support and show narrow size distributions, which suit photocatalysis applications. More importantly, the surfaces of the as-synthesised metal NPs are free of protecting ligands, enabling the photocatalysts to be ready to use without further treatment. The effect of the metal identity, the alloy chemical composition, and the microstructure on the photocatalytic performance has been investigated for hydrogen production and phenol decomposition. Whilst the photocatalytic H2 production performance can be great
    Dalton Transactions 10/2014; DOI:10.1039/C4DT01309C · 4.10 Impact Factor
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    ABSTRACT: Molybdenum blue (MB), a multivalent molybdenum oxide with a nano-ring morphology is well-known in analytical chemistry but, to date it has been largely ignored in other applications. In the present work, MB has been characterized by STEM-HAADF imaging for the first time, showing the nano-ring morphology of this complex molybdenum oxide and the ordered super-molecular framework crystals that can result from the self-assembly of these MB nano-ring units. The potential of MB as an oxidation catalyst has also been investigated, where it is shown to have excellent catalytic activity and stability in the selective oxidation of cyclohexane to cyclohexanol and cyclohexanone which are important intermediates in the production of nylon.
    10/2014; 5(1). DOI:10.1039/C4CY01213E
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    ABSTRACT: Supported gold nanoparticles are very effective catalysts for the selective oxidation of glycerol which represents an important bio-derived feedstock. In this paper we report that the effect of the acid/base properties, especially the acid site density, of these catalysts is the key factor available to tune the selectivity. A range of supported AuPt catalysts have been prepared by sol immobilization using acidic (H-Mordenite, SiO2, MCM-41, sulfated ZrO2) and basic (NiO, MgO) oxides as supports. In particular, using MCM-41 as support, a high selectivity to glyceraldehyde, an important labile intermediate, was found.
    10/2014; 5(2). DOI:10.1039/C4CY01246A
  • Handbook of Advanced Methods and Processes in Oxidation Catalysis. From Laboratory to Industry, 1st edited by Daniel Duprez, Fabrizio Cavani, 09/2014: chapter Supported metal nanoparticles in liquid-phase oxidation reactions: pages 631-678; World Scientific Publishing,., ISBN: 978848167506

Publication Stats

15k Citations
2,354.32 Total Impact Points

Institutions

  • 1998–2015
    • Cardiff University
      • School of Chemistry
      Cardiff, Wales, United Kingdom
  • 2006–2014
    • University of South Wales
      Понтиприте, Wales, United Kingdom
    • Universität Stuttgart
      • Institute of Organic Chemistry
      Stuttgart, Baden-Württemberg, Germany
  • 2005–2013
    • Lehigh University
      • Department of Materials Science and Engineering
      Bethlehem, PA, United States
  • 2010
    • University of Aberdeen
      • Department of Chemistry
      Aberdeen, Scotland, United Kingdom
  • 1999–2010
    • University of Reading
      • Department of Chemistry
      Reading, England, United Kingdom
    • University of Wales
      • Department of Chemistry
      Cardiff, Wales, United Kingdom
  • 1990–2010
    • University of Liverpool
      • Department of Chemistry
      Liverpool, England, United Kingdom
  • 1985–2010
    • University of the Witwatersrand
      • School of Chemistry
      Johannesburg, Gauteng, South Africa
  • 2003
    • University of California, Berkeley
      • Department of Materials Science and Engineering
      Berkeley, California, United States
    • University of Sistan and Baluchestan
      • Department of Chemistry
      Dowzdāb, Sīstān va Balūchestān, Iran
  • 2001
    • Loughborough University
      • Department of Chemistry
      Loughborough, England, United Kingdom
  • 1994–1997
    • French National Centre for Scientific Research
      • Institut de recherches sur la catalyse et l`environment de Lyon (IRCELYON)
      Lutetia Parisorum, Île-de-France, France
  • 1992–1997
    • University of Dundee
      Dundee, Scotland, United Kingdom
  • 1996
    • Nottingham Trent University
      Nottigham, England, United Kingdom