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Author: Peppel, Tim × End date: 2019 × Start date: 2010 × DDC: 600 × WGL Institute: LIKAT ×

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Now showing 1 - 2 of 2
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    Low-melting manganese(II)-based ionic liquids: Syntheses, structures, properties and influence of trace impurities
    (Basel : MDPI, 2019) Peppel, Tim; Geppert-Rybczyńska, Monika; Neise, Christin; Kragl, Udo; Köckerling, Martin
    The synthesis of more than 10 new magnetic ionic liquids with [MnX4]2− anions, X = Cl, NCS, NCO, is presented. Detailed structural information through single-crystal X-ray diffraction is given for (DMDIm)[Mn(NCS)4], (BnEt3N)2[Mn(NCS)4], and {(Ph3P)2N}2[Mn(NCO4)]·0.6H2O, respectively. All compounds consist of discrete anions and cations with tetrahedrally coordinated Mn(II) atoms. They show paramagnetic behavior as expected for spin-only systems. Melting points are found for several systems below 100 °C classifying them as ionic liquids. Thermal properties are investigated using differential scanning calorimetry (DSC) measurements. The physicochemical properties of density, dynamic viscosity, electrolytic conductivity, and surface tension were measured temperature-dependent of selected samples. These properties are discussed in comparison to similar Co containing systems. An increasing amount of bromide impurity is found to affect the surface tension only up to 3.3%.
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    Combination of chemo- and biocatalysis: Conversion of biomethane to methanol and formic acid
    (Basel : MDPI, 2019) Kunkel, Benny; Seeburg, Dominik; Peppel, Tim; Stier, Matthias; Wohlrab, Sebastian
    In the present day, methanol is mainly produced from methane via reforming processes, but research focuses on alternative production routes. Herein, we present a chemo-/biocatalytic oxidation cascade as a novel process to currently available methods. Starting from synthetic biogas, in the first step methane was oxidized to formaldehyde over a mesoporous VOx/SBA-15 catalyst. In the second step, the produced formaldehyde was disproportionated enzymatically towards methanol and formic acid in equimolar ratio by formaldehyde dismutase (FDM) obtained from Pseudomonas putida. Two processing routes were demonstrated: (a) batch wise operation using free formaldehyde dismutase after accumulating formaldehyde from the first step and (b) continuous operation with immobilized enzymes. Remarkably, the chemo-/biocatalytic oxidation cascades generate methanol in much higher productivity compared to methane monooxygenase (MMO) which, however, directly converts methane. Moreover, production steps for the generation of formic acid were reduced from four to two stages. © 2019 by the authors.