Explaining the role of vanadium in homogeneous glucose transformation reactions using NMR and EPR spectroscopy

Albert, Jakob; Mendt, Matthias; Mozer, Michael C.; Voß, Dorothea

doi:10.1016/j.apcata.2018.10.030

Cited by 30 publications

(49 citation statements)

References 53 publications

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“…A reason for the higher FA‐yield observed for the POM‐Ionosolv concept with higher water content (40 wt%) compared to the classical ionosolv treatment (20 wt.%) could be that the water content affects the type of vanadium species that is formed. It is known that the oxidation of dissolved carbohydrates is highly dependent on the vanadium species present in the liquid phase . To verify this we carried out 51 V NMR spectral analysis.…”

Section: Resultsmentioning

confidence: 99%

“…It is known that the oxidation of dissolved carbohydrates is highly dependent on the vanadium species present in the liquid phase. [59] To verify this we carried out 51 Figure S1) showed predominantly the expected HPA-5 species (À 560 ppm), whereas the 51 V NMR spectrum of HPA-5 in [TEA] [HSO 4 ] with 20 wt.% H 2 O (Supporting Information, Figure S3) showed the presence of lower V substituted species such as HPA-1 (À 533 ppm) and HPA-2 (À 537 ppm), as well as VO 2 + /HPA-3 (broad peak at À 540 to À 560 ppm) and the decavanadate species H 2 V 10 O 28 4À (À 510 ppm). As the more highly substituted HPA species are known to be the most active ones for oxidative formic acid production from lignocellulosic biomass, the higher yield and selectivity observed for the IL solution containing 40 wt.% water is likely due to the HPA-5 catalyst species being stable at this water content.…”

Section: Influence Of the Water Content In The New Pom-ionosolv Conceptmentioning

confidence: 99%

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Combining Cost‐Efficient Cellulose and Short‐Chain Carboxylic Acid Production: The Polyoxometalate (POM)‐Ionosolv Concept

et al. 2020

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Full cost‐effective exploitation of all wood components is key to growing a commercially successful biorefining industry. An innovative process is reported that combines fractionation of lignocellulosic biomass using a low‐cost ionic liquid (Ionosolv) and production of bio‐derived formic acid using polyoxometalates and molecular oxygen (OxFA process). We show that the hemicellulose and part of the lignin were selectively dissolved into the ionic liquid triethylammonium hydrogen sulfate and oxidised in situ to short‐chain, distillable carboxylic acids by a Keggin‐type polyoxometalate with high yields and selectivities. Characterization by several techniques, including ICP‐OES, FTIR, GC, HPLC and NMR spectroscopy confirmed stability of the catalyst over three consecutive POM‐Ionosolv recycles and stable formic acid yields.High formic acid yields of 26 % (pine chips), 23 % (beech chips), and 18 % (Miscanthus) were obtained with respect to the initial carbon content of the biomass, with unprecedented oxidation selectivities for formic acid of 54–62 % depending on vanadium substitution in the polyoxometalate, the processing temperature and the water content in the reaction mixture.. We also demonstrate that the cellulose rich pulp is a suitable source of glucose via enzymatic saccharification. We report cellulose yields of 37% for Miscanthus (from originally 48% glucan content), 33% for pine (from originally 49%) and 31% for beech (from originally 41%) were achieved, and a saccharification yield of up to 25% without optimisation. With further optimisation, this concept has the potential to generate two chemical products directly from lignocellulose in high yields and selectivities and hence a novel avenue for full utilisation of cellulose, hemicellulose and lignin.

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Section: Resultsmentioning

confidence: 99%

Section: Influence Of the Water Content In The New Pom-ionosolv Conceptmentioning

confidence: 99%

Combining Cost‐Efficient Cellulose and Short‐Chain Carboxylic Acid Production: The Polyoxometalate (POM)‐Ionosolv Concept

et al. 2020

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“…This product distribution is well in line with literature proposed reaction pathways. [7][8][9] GA is the intermediate product of the oxidation of glucose to formic acid and CO 2 , while AA is most likely formed by thermal induced conversion of glucose to HMF and levulinic acid (LA) (see Fig. 3).…”

Section: Inuence Of Nb-and Ta-doping On Product Distribution At Highmentioning

confidence: 99%

“…Hereby, mostly vanadiumcontaining catalysts like polyoxometalates (POMs), [5][6][7] or water-soluble vanadium salts are used. 8,9 In particular POMs are highly promising catalysts for these kinds of reaction due to their strong Brønsted acidity combined with a high redox activity and high stability in aqueous solution. 10,11 Within the redox-cycle, shown schematically in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Combining autoclave and LCWM reactor studies to shed light on the kinetics of glucose oxidation catalyzed by doped molybdenum-based heteropoly acids

et al. 2019

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In this work we combined kinetic studies for aqueous-phase glucose oxidation in a high-pressure autoclave setup with catalyst reoxidation studies in a liquid-core waveguide membrane reactor. Hereby, we investigated the influence of Nb-and Ta-doping on Mo-based Keggin-polyoxometalates for both reaction steps independently. Most importantly, we could demonstrate a significant increase of glucose oxidation kinetics by Ta-and especially Nb-doping by factors of 1.1 and 1.5 compared to the classical HPA-Mo. Moreover, activation energies for the substrate oxidation step could be significantly reduced from around 80 kJ mol À1 for the classical HPA-Mo to 61 kJ mol À1 for the Ta-and 55 kJ mol À1 for the Nb-doped species, respectively. Regarding catalyst reoxidation kinetics, the doping did not show significant differences between the different catalysts.

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Alcohol‐Activated Vanadium‐Containing Polyoxometalate Complexes in Homogeneous Glucose Oxidation Identified with ⁵¹V‐NMR and EPR Spectroscopy

2021

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Alcoholic solvents, especially methanol, show an activating affect for heteropolyacids in homogenously catalysed glucose transformation reactions. In detail, they manipulate the polyoxometalate‐based catalyst in a way that thermodynamically favoured total oxidation to CO2 can be completely supressed. This allows a nearly 100 % carbon efficiency in the transformation reaction of glucose to methyl formate in methanolic solution at mild reaction conditions of 90 °C and 20 bar oxygen pressure. By using powerful spectroscopic tools like 51V‐NMR and continuous wave EPR we could unambiguously prove that the vanadate‐methanol‐complex[VO(OMe)3]n is responsible for the selectivity shift in methanolic solution compared to the aqueous reference system.

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Explaining the role of vanadium in homogeneous glucose transformation reactions using NMR and EPR spectroscopy

Cited by 30 publications

References 53 publications

Combining Cost‐Efficient Cellulose and Short‐Chain Carboxylic Acid Production: The Polyoxometalate (POM)‐Ionosolv Concept

Combining Cost‐Efficient Cellulose and Short‐Chain Carboxylic Acid Production: The Polyoxometalate (POM)‐Ionosolv Concept

Combining autoclave and LCWM reactor studies to shed light on the kinetics of glucose oxidation catalyzed by doped molybdenum-based heteropoly acids

Alcohol‐Activated Vanadium‐Containing Polyoxometalate Complexes in Homogeneous Glucose Oxidation Identified with ⁵¹V‐NMR and EPR Spectroscopy

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Explaining the role of vanadium in homogeneous glucose transformation reactions using NMR and EPR spectroscopy

Cited by 30 publications

References 53 publications

Combining Cost‐Efficient Cellulose and Short‐Chain Carboxylic Acid Production: The Polyoxometalate (POM)‐Ionosolv Concept

Combining Cost‐Efficient Cellulose and Short‐Chain Carboxylic Acid Production: The Polyoxometalate (POM)‐Ionosolv Concept

Combining autoclave and LCWM reactor studies to shed light on the kinetics of glucose oxidation catalyzed by doped molybdenum-based heteropoly acids

Alcohol‐Activated Vanadium‐Containing Polyoxometalate Complexes in Homogeneous Glucose Oxidation Identified with 51V‐NMR and EPR Spectroscopy

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Alcohol‐Activated Vanadium‐Containing Polyoxometalate Complexes in Homogeneous Glucose Oxidation Identified with ⁵¹V‐NMR and EPR Spectroscopy