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.

Performance criteria and nomenclature in electrochemical engineering

Abstract: This paper is a recommendation of the Working Party on Electrochemical Engineering of the European Federation of Chemical Engineering. It was prepared by a sub-committee composed of: G. Kreysa (Frankfurt am Main) Chairman F. Coeuret (Rennes) A. Storck (Nancy) H. Wendt (Darmstadt) The helpful discussions and comments of colleagues in the Working Party are gratefully acknowledged.

Reaktions- und verfahrenstechnische Aspekte elektrochemischer Fest- und Wirbelbett-Zellen

Abstract: Elektrochemische Festbett- und Wirbelbett-Zellen eignen sich in hervorragender Weise fur eine Anwendung bekannter verfahrens- und reaktionstechnischer Prinzipien aus dem Gebiet der technischen Chemie. Die Makrokinetik dieser Elektrodensysteme weist einige Besonderheiten auf, die sich auf die Vergroserung der spezifischen Elektroden-Oberflachen, die Intensivierung des Stofftransports und die Potentialverteilung in der Elektrode zuruckfuhren lassen. Unter Beachtung gewisser Restriktionen, wie sie durch die wirksame Betthohe gegeben sind, konnen auf der Grundlage der Theorie des Stromungsrohrreaktors brauchbare Naherungsformeln fur das Scale-up entwickelt werden. Das technische Potential von Festbett- und Wirbelbettzellen liegt hauptsachlich auf dem Gebiet der Metallabscheidung aus verdunnten Losungen, Oxidation oder Reduktion von anorganischen und organischen Reaktanden niedriger Konzentration sowie der Umsetzung von Spurenbestandteilen, z. B. Verunreinigungen. Die Entwicklungsarbeiten konzentrieren sich im wesentlichen auf die Gewinnung von Metallen aus armen Erzen und Ablaugen niedriger Konzentration sowie auf die Reinigung von Abwassern.

Investigation of the effect of the alloy 600 substrate for the stability of a Ni3Sn2 coating for metal dusting protection at 620 °C

Abstract: Under specific conditions carbon containing gas species can attack and degrade steels and nickel base alloys via a corrosion mechanism called metal dusting. These conditions occur at temperatures in the range of 400 to 800 °C, low oxygen partial pressures and carbon activities higher than one. Carbon activity higher than one means that the gas phase is out of equilibrium but due to high gas velocities carbon segregation is kinetically hindered by simply reducing the holding time of the gas in the critical temperature range. The kinetic hindering is superimposed by the catalytic activation of the deposition process by the metal surfaces of reactors. High amounts of atomic carbon deposit on the metal surface, diffuse inwards into the material and precipitate as graphite in the metal matrix causing the total disintegration and the formation of ‘metal dust’. Metals triggering this corrosion attack include iron, nickel and cobalt. To inhibit the catalytic activation of the carbon deposition a catalytic poisoning concept has been invented. Tin has been shown to be very useful to occupy the catalytical active centers of nickel on the metal surface via the formation of the intermetallic Ni 3 Sn 2 -phase for at least 3000 h of exposure at 620 °C. The performance of the coating does not only depend on its stability towards the aggressive atmosphere but is also strongly determined by the diffusion processes occurring at the coating/substrate interface. On nickel base alloys the Ni 3 Sn 2 -phase should transform into the Ni 3 Sn phase due to the vicinity of a high nickel reservoir but this was not observed for the substrate alloy 600 after 3000 h of exposure. This behavior was investigated in this work and shall be focused on in this article to gain a better understanding of the coating/substrate interaction for a better lifetime prediction.

Product recovery of an enzymatically synthesized (-)-menthol ester in a deep eutectic solvent.

Abstract: Deep eutectic solvents (DESs) have gained increased attention as alternative reaction media for biocatalysis in recent years. There are many investigations on biotransformations in a variety of DESs, but the purification of bioproducts from DES reaction mixtures has not yet been sufficiently addressed. The present study demonstrates a product recovery strategy from a DES reaction medium composed of (−)-menthol and dodecanoic acid. Since the DES is not formed by equimolar amounts of the substrates, but the eutectic point occurs at a 3:1 molar ratio, product isolation is an important task for effective biocatalytic process development, even if the limiting substrate is converted completely. Both DES compounds acted as substrates and reaction solvent in the lipase-catalyzed esterification to synthesize (−)-menthyl dodecanoate. The product (−)-menthyl dodecanoate ester was separated from the DES reaction mixture by a vacuum distillation step and a second esterification reaction can be performed with the recovered (−)-menthol.