DECHEMA

About: DECHEMA is a nonprofit organization based out in Frankfurt am Main, Germany. It is known for research contribution in the topics: Corrosion & Oxide. The organization has 756 authors who have published 1307 publications receiving 25693 citations.

Indirect electrochemical degradation and dissolution of coal by means of persulphate

Abstract: The idea of electrochemical coal conversion has recently been revived1–7. The mechanism of anodic coal oxidation has been shown to be indirect and that the electron transfer is mediated by Fe3+/Fe2+ leached out of the coal. Although the application of various mediator systems has been discussed in detail, all these systems suffer from either comparatively low reaction rates or high CO2– current efficiencies. Caro's acid (H2SO5), obtained as a hydrolysis product during anodic persulphate formation is a powerful redox mediater system for the degradation of the macromolecular coal structure in mild conditions, providing a nearly complete dissolution of coal in sulphuric acid. We propose here that the high current efficiencies accompanied by low CO2 evolution might open a route of potential interest for the electrochemical production of aromatic carboxylic acids from coal.

An Overview and Future Perspectives of Aluminum Batteries

Abstract: A critical overview of the latest developments in the aluminum battery technologies is reported. The substitution of lithium with alternative metal anodes characterized by lower cost and higher abundance is nowadays one of the most widely explored paths to reduce the cost of electrochemical storage systems and enable long-term sustainability. Aluminum based secondary batteries could be a viable alternative to the present Li-ion technology because of their high volumetric capacity (8040 mAh cm(-3) for Al vs 2046 mAh cm(-3) for Li). Additionally, the low cost aluminum makes these batteries appealing for large-scale electrical energy storage. Here, we describe the evolution of the various aluminum systems, starting from those based on aqueous electrolytes to, in more details, those based on non-aqueous electrolytes. Particular attention has been dedicated to the latest development of electrolytic media characterized by low reactivity towards other cell components. The attention is then focused on electrode materials enabling the reversible aluminum intercalation-deintercalation process. Finally, we touch on the topic of high-capacity aluminum-sulfur batteries, attempting to forecast their chances to reach the status of practical energy storage systems.

Effect of Pressure on Metal Dusting Initiation on Alloy 800H and Alloy 600 in CO-rich Syngas

Abstract: The effect of pressure on metal dusting initiation was studied by exposing conventional alloys 600 and 800H in CO-rich syngas atmosphere (H2, CO, CO2, CH4, H2O) at ambient and 18 bar total system pressure and 620 °C for 250 h. It was verified that, at constant temperature, increasing the total system pressure increases both oxygen partial pressure (pO2) and carbon activity (a C), simultaneously. Both samples exposed at ambient pressure showed very thin oxide scale formation and no sign of metal dusting. By contrast, samples exposed in the high-pressure experiment showed severe mass loss by metal dusting attack. Iron- and chromium-rich oxides and carbides were found as corrosion products. The distinct pressure-dependent behavior was discussed by considering both thermodynamic and kinetic aspects with respect to the protective oxide formation and pit initiation.

Sauerstoffaufnahme von Vanadium, Niob und Tantal bei hohen Temperaturen und niedrigen Drücken

Abstract: Es wird eine Ubersicht uber die Sauerstoffaufnahme von Vanadium, Niob und Tantal bei Temperaturen oberhalb von 1000°C und bei Sauerstoffpartialdrucken unterhalb von 10−2 Torr gegeben. Dabei wird die Kinetik der Sauerstofflosung ausfuhrlich behandelt und auf die Oxidation nur kurz eingegangen. Die Ubersicht enthalt eine theoretische Behandlung der Sauerstofflosung. Fernerhin werden quantitative Beziehungen angegeben, die eine Abschatzung der Sauerstofflosung in Vanadium, Niob und Tantal bei gegebenen Bedingungen von Temperatur und Sauerstoffdruck erlauben. Oxygen absorption by vanadium, niobium and tantalum at high temperatures and low pressures A general view is presented of the oxygen absorption by vanadium, niobium and tantalum at temperatures above 1000°C and at oxygen partial pressures below 10−2 torr. In this context the kinetics of oxygen dissolution is given a detailed treatment while oxidation is dealt with but shortly. The review includes a theoretical treatment of oxygen dissolution. In addition quantitative relations are given which enable the oxygen dissolution in vanadium, niobium and tantalum to be estimated at given conditions of temperature and oxygen pressure.