Esben Taarning

Haldor Topsøe, Lyngby, Capital Region, Denmark

Are you Esben Taarning?

Claim your profile

Publications (25)137.48 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Furylglycolic acid (FA), a pseudoaromatic hydroxy-acid suitable for copolymerization with lactic acid, can be produced from glucose via enzymatically derived cortalcerone using a combination of Brønsted and Lewis acid catalysts. Cortalcerone is first converted to furylglyoxal hydrate (FH) over a Brønsted acid site (HCl or Al-containing beta-zeolite), and FH is subsequently converted to FA over a Lewis acid site (Sn-beta zeolite). Selectivity for conversion of FH to FA is as high as 80% at 12% conversion using tetrahydrofuran (THF) as a solvent at 358 K. Higher conversion of FH leads to FA-catalyzed degradation of FH and subsequent deactivation of the catalyst by the deposition of carbonaceous residues. The deactivated catalyst can be regenerated by calcination. Cortalcerone can be produced from 10% glucose solution using recombinant Escherichia coli strains expressing pyranose 2-oxidase and aldos-2-ulose dehydratase from the wood-decay fungus Phanerochaete chrysosporium BKM-F-1767. This enzymatically derived cortalcerone is converted in one pot to FA in a methanol/water solvent over an Al-containing Sn-beta zeolite possessing both Brønsted and Lewis acid sites, achieving 42% selectivity to FA at 53% cortalcerone conversion.
    ACS Catalysis 10/2013; 3(12):2689–2693. · 5.27 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Solid acid catalysts were studied at temperatures near 523 K for the production of benzene, toluene, and p-xylene by the reaction of ethylene with furan, 2-methylfuran, and 2,5-dimethylfuran, respectively, through the combination of cycloaddition and dehydrative aromatization reactions. Catalysts containing Brønsted acid and Lewis acid sites (i.e., WOx–ZrO2, niobic acid, zeolite Y, silica–alumina) were more active than catalysts containing predominantly Lewis acid sites (γ-Al2O3, TiO2), which indicates the importance of Brønsted acidity in the production of aromatics. Microporosity is not required for this reaction, because amorphous solid acids and homogeneous Brønsted acids demonstrate significant activity for p-xylene production. The production of p-xylene from 2,5-dimethylfuran proceeded at higher rates compared with the production of toluene and benzene from 2-methylfuran and furan, respectively. Both WOx–ZrO2 and niobic acid demonstrate superior activity for aromatics production than does zeolite Y. WOx–ZrO2 demonstrates a turnover frequency for p-xylene production that is 35 times higher than that demonstrated by zeolite Y. In addition, mesoporous materials such as WOx–ZrO2 offer higher resistance to deactivation by carbon deposition than do microporous materials. Results from Raman spectroscopy and the trend of turnover frequency with varying tungsten surface densities for a series of WOx–ZrO2 catalysts are consistent with previous investigations of other acid-catalyzed reactions; this suggests that the high reactivity of WOx–ZrO2 is mainly associated with the presence of subnanometer WOx clusters mixed with zirconium, which reach a maximum surface concentration at intermediate tungsten coverage.
    ChemCatChem 07/2013; 5(7). · 5.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The selective conversion of biomass-derived substrates is one of the major challenges facing the chemical industry. Recently stannosilicates have been employed as highly active and selective Lewis acid catalysts for a number of industrially relevan reactions. In the present work, four different stannosilicates have been investigated: Sn-BEA, Sn-MFI, Sn-MCM-41 and Sn-SBA-15. When comparing the properties of tin sites in the structures, substantial differences are observed. Sn-beta displays the highes Lewis acid strength, as measured by probe molecule studies using infrared spectroscopy, which gives it a significantly highe activity at low temperatures than the other structures investigated. Furthermore, the increased acid strength translates int large differences in selectivity between the catalysts, thus demonstrating the influence of the structure on the active site and pointing the way forward for tailoring the active site to the desired reaction.
    Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences 07/2012; 468(2143):2000-2016. · 2.38 Impact Factor
  • 03/2012;
  • ChemInform 02/2012; 43(7).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Conversions of various pentoses and hexoses into methyl lactate has been demonstrated for the Sn-Beta catalyst. It is found that pentoses are converted to methyl lactate in slightly lower yields (40%) than what is obtained for hexoses (50%), but higher yields of glycolaldehyde dimethyl acetal are observed for the pentoses. This finding is in accordance to a reaction pathway that involves the retro aldol condensation of the sugars to form a triose and glycolaldehyde for the pentoses, and two trioses for hexoses. When reacting glycolaldehyde (formally a C2-sugar) in the presence of Sn-Beta, aldol condensation occurs, leading to the formation of methyl lactate, methyl vinylglycolate and methyl 2-hydroxy-4-methoxybutanoate. In contrast, when converting the sugars in water at low temperatures (100 °C), Sn-Beta catalyses the isomerisation of sugars (ketose–aldose epimers), rather than the formation of lactates.
    Green Chemistry 01/2012; 14(3):702-706. · 6.83 Impact Factor
  • Angewandte Chemie 11/2011; 123(45).
  • Angewandte Chemie International Edition 11/2011; 50(45):10502-9. · 11.34 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Heterogeneous catalysts have been a central element in the efficient conversion of fossil resources to fuels and chemicals, but their role in biomass utilization is more ambiguous. Zeolites constitute a promising class of heterogeneous catalysts and developments in recent years have demonstrated their potential to find broad use in the conversion of biomass. In this perspective we review and discuss the developments that have taken place in the field of biomass conversion using zeolites. Emphasis is put on the conversion of lignocellulosic material to fuels using conventional zeolites as well as conversion of sugars using Lewis acidic zeolites to produce useful chemicals.
    Energy & Environmental Science 03/2011; 4(3):793-804. · 11.65 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hierarchical (or mesoporous) zeolites have attracted significant attention during the first decade of the 21st century, and so far this interest continues to increase. There have already been several reviews giving detailed accounts of the developments emphasizing different aspects of this research topic. Until now, the main reason for developing hierarchical zeolites has been to achieve heterogeneous catalysts with improved performance but this particular facet has not yet been reviewed in detail. Thus, the present paper summaries and categorizes the catalytic studies utilizing hierarchical zeolites that have been reported hitherto. Prototypical examples from some of the different categories of catalytic reactions that have been studied using hierarchical zeolite catalysts are highlighted. This clearly illustrates the different ways that improved performance can be achieved with this family of zeolite catalysts. Finally, future opportunities for hierarchical zeolite catalysts are discussed, and the virtues of various preparation methods are outlined, including a discussion of possible pitfalls in the evaluation of new, potential hierarchical zeolite catalysts.
    Catalysis Today - CATAL TODAY. 01/2011; 168(1):3-16.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Presently, very few compounds of commercial interest are directly accessible from carbohydrates by using nonfermentive approaches. We describe here a catalytic process for the direct formation of methyl lactate from common sugars. Lewis acidic zeotypes, such as Sn-Beta, catalyze the conversion of mono- and disaccharides that are dissolved in methanol to methyl lactate at 160 degrees C. With sucrose as the substrate, methyl lactate yield reaches 68%, and the heterogeneous catalyst can be easily recovered by filtration and reused multiple times after calcination without any substantial change in the product selectivity.
    Science 04/2010; 328(5978):602-5. · 31.20 Impact Factor
  • ChemCatChem 01/2010; 2(8):943-945. · 5.18 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Lactic acid is an interesting platform chemical with many promising applications. This includes the use as a building block for the production of biodegradable plastics and environmentally friendly solvents. A study of the liquid-phase conversion of the triose-sugars, glyceraldehyde and dihydroxyacetone directly to methyl lactate and lactic acid catalyzed by inexpensive commercially available zeolites is presented. One particular zeolite, H-USY (Si/Al=6) is shown to be quite active with near quantitative yields for this isomerization. Deactivation of the H-USY-zeolite was studied by correlating the catalytic activity to data obtained by TPO, XRD, N2-sorption, and NH3-TPD on fresh and used catalysts. Coking and irreversible framework damage occurs when lactic acid is produced under aqueous conditions. In methanol, methyl lactate is produced and catalyst deactivation is suppressed. Additionally, reaction rates for the formation of methyl lactate in methanol are almost an order of magnitude higher as compared to the rate of lactic acid formation in water.
    Journal of Catalysis - J CATAL. 01/2010; 269(1):122-130.
  • [Show abstract] [Hide abstract]
    ABSTRACT: This Full Paper illustrates the use of the C factor (CO(2)/product mass ratio) as a parameter to evaluate the CO(2)-burden of a product. The C factor contains information of the total amount of CO(2) emitted in order to produce a product, and thus enables a direct comparison of different processes from a CO(2) aspect. We illustrate how this simple concept can be used to evaluate different resource types and processes. The C factors for different chemicals such as methanol, synfuels, and acetic acid are calculated for oil, coal, natural gas, and biomass. Based on these calculations, the combination of biomass and natural gas is an attractive alternative to coal, leading to products that have significantly lower C factors.
    ChemSusChem 12/2009; 2(12):1152-62. · 7.48 Impact Factor
  • ChemSusChem 07/2009; 2(7):625-7. · 7.48 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2009; 40(50).
  • Source
    Esben Taarning, Robert Madsen
    [Show abstract] [Hide abstract]
    ABSTRACT: A one-pot procedure is described for using alpha,beta-unsaturated aldehydes as olefin equivalents in the Diels-Alder reaction. The method combines the normal electron demand cycloaddition with aldehyde dienophiles and the rhodium-catalyzed decarbonylation of aldehydes to afford cyclohexenes with no electron-withdrawing substituents. In this way, the aldehyde group serves as a traceless control element to direct the cycloaddition reaction. The Diels-Alder reactions are performed in a diglyme solution in the presence of a catalytic amount of boron trifluoride etherate. Subsequent quenching of the Lewis acid, addition of 0.3% of [Rh(dppp)2Cl] and heating to reflux achieves the ensuing decarbonylation to afford the product cyclohexenes. Under these conditions, acrolein, crotonaldehyde and cinnamaldehyde have been reacted with a variety of 1,3-dienes to afford cyclohexenes in overall yields between 53 and 88%. In these transformations, the three aldehydes serve as equivalents of ethylene, propylene and styrene, respectively.
    Chemistry 07/2008; 14(18):5638-44. · 5.83 Impact Factor
  • ChemSusChem 02/2008; 1(1-2):75-8. · 7.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The possibilities for establishing a renewable chemicals industry featuring renewable resources as the dominant feedstock rather than fossil resources are discussed in this Concept. Such use of biomass can potentially be interesting from both an economical and ecological perspective. Simple and educational tools are introduced to allow initial estimates of which chemical processes could be viable. Specifically, fossil and renewables value chains are used to indicate where renewable feedstocks can be optimally valorized. Additionally, C factors are introduced that specify the amount of CO2 produced per kilogram of desired product to illustrate in which processes the use of renewable resources lead to the most substantial reduction of CO2 emissions. The steps towards a renewable chemicals industry will most likely involve intimate integration of biocatalytic and conventional catalytic processes to arrive at cost-competitive and environmentally friendly processes.
    ChemSusChem 02/2008; 1(4):283-9. · 7.48 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Over the past decades it has become clear that supported gold nanoparticles are surprisingly active and selective catalysts for several green oxidation reactions of oxygen-containing hydrocarbons using molecular oxygen as the stoichiometric oxidant. We here report that bifunctional gold–titaniacatalysts can be employed to facilitate the oxidation of amines into amides with high selectivity. Furthermore, we report that pure titania is in fact itself a catalyst for the oxidation of amines with molecular oxygen under very mild conditions. We demonstrate that these new methodologies open up for two new and environmentally benign routes to caprolactam and cyclohexanone oxime, both of which are precursors for nylon-6.
    Green Chemistry 01/2008; 10(4). · 6.83 Impact Factor