Ecological and Economic Evaluation of Hydrogen Production by Different Water Electrolysis Technologies

The economic and ecological production of green hydrogen by water electrolysis is one of the major challenges within Carbon2Chem® and other power-to-X projects. This paper presents an evaluation of the different water electrolysis technologies with respect to their specific energy demand, carbon footprint and the forecast production costs in 2030. From a current perspective alkaline water electrolysis is evaluated as the most favorable technology for the cost-effective production of low-carbon hydrogen with fluctuating renewables.     

Indentation densification of fused silica assessed by raman spectroscopy and constitutive finite element analysis

Inelastic deformation of anomalous glasses manifests in shear flow and densification of the glass network; the deformation behavior during indentation testing is linked strongly to both processes. In this paper, the indentation densification field of fused silica is investigated using depth-resolved Raman spectroscopy and finite element simulations. Through affecting the size of the indent, the normal load and the Raman laser spot size determine the spatial sampling resolution, leading to a certain degree of structural averaging. For appropriate combinations of normal load (indent size) and laser spot diameter, a maximum densification of 18.4% was found at the indent center. The indentation behavior was modeled by extended Drucker-Prager-Cap (DPC) plasticity, assuming a sigmoidal hardening behavior of fused silica with a densification saturation of 21%. This procedure significantly improved the reproduction of the experimental densification field, yielding a maximum densification of 18.2% directly below the indenter tip. The degree of densification was found to be strongly linked to the hydrostatic pressure limit below the indenter in accordance to Johnson's expanding cavity model (J. Mech. Phys. Solids, 18 (1970) 115). Based on the good overlap between FEA and Raman, an alternative way to extract the empirical correlation factor m, which scales structural densification to Raman spectroscopic observations, is obtained. This approach does not require the use of intensive hydrostatic compaction experiments.     

Erster und zweiter Rettungsweg in Wohngebäuden

First and second escape ways in residential buildings The existence of two redundant escape ways is a fundamental concept to ensure a safe egress of occupants in the event of fire. Fire safety requirements for means of egress are defined by the state specific building codes in Germany. This publication focuses on a further clarification of existing requirements and amongst others explains why some means of egress, such as permanent installed ladders are not suitable for this purpose. However, in contrast to this fire service equipment can also provide the second escape way in particularly for residential buildings. Different means are used depending on the applied strategy and infrastructure of the fire service. A summary of reported fire incidents of the Berlin fire service in the years 2012 and 2013 shows that smoke filled stairwells were also used to evacuate trapped occupants. In order to protect these occupants from smoke intoxication, escape hoods or positive pressure ventilation fans, to allow for a smoke free stairwell, have been used.     

Darstellung und selektive Komplexbildung von Bisorganylsulfiden auf [2.2.2]Paracyclophan‐Basis

The synthesis of a variety of novel functionalized bisorganyl sulfides 2 – 10 based on the [2.2.2]paracyclophane skeleton is described. The aim was to increase the endohedral silver(I) complexation of the unsubstituted [2.2.2]paracyclophane 1 by combining the cyclophane framework with a sulfur containing pendant arm bearing an additional π‐donor. The complexation behaviour of the new ligands was studied by liquid–liquid extraction from aqueous into organic solution. The new ligands reveal a higher extraction with a decreased selectivity for silver(I) compared to 1 caused by preferential interactions with the sulfur donor atoms in the molecule. Molecular modeling calculations show the different coordination patterns for the 1:1‐, 1:2‐ and 2:1‐complexes (M:L) formed in the organic phase.     

Oxidation of Hydroquinones and Hydroquinone Monomethyl Ethers to Quinones with tert‐Butyl Hydroperoxide and Catalytic Amounts of Ceric Ammonium Nitrate (CAN)

Mono‐ and bicyclic hydroquinones and hydroquinone monomethyl ethers 1, 2 are oxidized in 82—91% yield to the corresponding quinones using only 2 mol% of ceric ammonium nitrate (CAN) and 2.5 equivalents of tert‐butyl hydroperoxide.