Christian Knoll

An unusually water-poor 5,5′-azobistetrazolate of dysprosium: stabilization of a nitrogen-rich heterocycle by a minimum of hydrogen bonds

In inorganic 5,5′-azobistetrazolate (C2N102−; ZT) compounds, the energetic ZT moiety is usually stabilized by H-bonds to lattice H2O and/or coordination of an N-atom of the tetrazole ring to the metal ion. Here we present the synthesis and characterization of a novel, salt-like compound, [Dy(H2O)8]2ZT3, which constitutes a unique exception to the above rule. We used supercritical CO2 as an unconventional desiccant in a straightforward metathesis reaction without abstaining from the benefits aqueous chemistry offers. It caused the crystallization of the title compound with a complex system of H-bonds between [Dy(H2O)8]3+ and ZT2− that involves almost every N-atom of the ZT2− anions as H-bond acceptors, which sufficiently stabilizes the energetic ZT despite the lack of lattice H2O or a coordinative bond to the metal ion.

Cycle Stability and Hydration Behavior of Magnesium Oxide and Its Dependence on the Precursor-Related Particle Morphology

Thermochemical energy storage is considered as an auspicious method for the recycling of medium-temperature waste heat. The reaction couple Mg(OH)2–MgO is intensely investigated for this purpose, suffering so far from limited cycle stability. To overcome this issue, Mg(OH)2, MgCO3, and MgC2O4·2H2O were compared as precursor materials for MgO production. Depending on the precursor, the particle morphology of the resulting MgO changes, resulting in different hydration behavior and cycle stability. Agglomeration of the material during cyclization was identified as main reason for the decreased reactivity. Immersion of the spent material in liquid H2O decomposes the agglomerates restoring the initial reactivity of the material, thus serving as a regeneration step.

Methodology to determine the apparent specific heat capacity of metal hydroxides for thermochemical energy storage

Thermochemical energy storage uses reversible thermochemical reactions to store and release heat, representing a promising technology for energy conservation and utilizing fluctuating renewable energy sources and waste heat. Many recent studies have focused on determination of the enthalpy of reaction of possible thermochemical materials (TCM) based on thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). So far, comparatively few attempts have been made to characterize the apparent specific heat capacity at constant pressure

A Modified Synthetic Pathway for the Synthesis of so far Inaccessible N1-Functionalized Tetrazole Ligands – Synthesis and Characterization of the 1D Chain-Type Spin Crossover Compound [Fe(3ditz)3](BF4)2

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High-Temperature Energy Storage: Kinetic Investigations of the CuO/Cu2O Reaction Cycle

cpappT of the investigated TCM. The purpose of this study is to outline a measurement and analysis procedure to evaluate

Combining in-situ X-ray diffraction with thermogravimetry and differential scanning calorimetry – An investigation of Co3O4, MnO2 and PbO2 for thermochemical energy storage

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