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.

Electrode for use in electrolytic processes

Abstract: The invention relates to an electrode for use in electrolytic processes, whose electrochemically active surface consists at least in part of an amorphous alloy which contains at least two of the metals iron, nickel and cobalt as essential constituents. The amorphous alloys used in the electrode according to the invention have considerably lower overvoltages for the electrochemical generation of hydrogen and/or oxygen and thus have a better electrocatalytic behaviour than any of their metallic basic constituents.

Integrierte Bioproduktion und selektive Aufreinigung von Perillasäure

Abstract: Fur die erfolgreiche industrielle Anwendung biotechnologischer Produktionsverfahren sind hohe Raum-Zeit-Ausbeuten und kostengunstige Aufreinigungsverfahren essenziell. Fur produktinhibierte Bioprozesse stellt die Integration einer In-situ-Produktabtrennung (in situ product removal, ISPR) einen vielversprechenden Losungsansatz dar. Der vorliegende Beitrag beschreibt das Vorgehen fur die Optimierung der mikrobiellen Umwandlung von Limonen zu Perillasaure, einer bioaktiven Monoterpensaure, mittels ISPR.

Untersuchungen über die Korrosion einiger Metalle und Metalloxyde in Natriumhydroxydschmelzen

Abstract: Ziel der Untersuchungen war, einen Beitrag zur Aufklarung der Reaktionsablaufe zu leisten, die in den besonders fur die Entzunderung von hochlegierten Chrom- und Chrom-Nickel-Stahlen benutzten Die Untersuchungen erfolgten an den Metallen Silber, Gold, Platin, Nickel und Eisen und an den Metalloxyden FeO, Fe3O4, Fe2O3 und Cr2O3 in NaOH-Schmelzen bei Temperaturen um 500°C. Besondere Aufmerksamkeit wurde dem Einflus der Gasatmosphare auf die Korrosionsgeschwindigkeit gewidmet. Mit Ausnahme des Silbers ist die Korrosion aller untersuchten Metalle und Oxyde unter Sauerstoff erheblich groser als unter Stickstoff, wobei ein Zusatz von Wasserdampf besonders unter Sauerstoff die Korrosion stark inhibiert. Unter wasserdampfhaltigem Stickstoff ist der Angriff der reinen NaOH-Schmelzen praktisch vernachlassigbar. Nur Silber korrodiert bei Gegenwart von Wasserdampf starker als unter trockenen Gasen. Die Korrosionsprodukte wurden chemisch, metallographisch sowie durch Rontgen- und Elektronenbeugung untersucht. Die geringe Korrosion unter Stickstoff zeigt, das die Reaktion zwischen Metallen bzw. Metalloxyden und der NaOH-Schmelze nicht oder nur recht langsam ablauft. Die beschleunigende Wirkung des Sauerstoffs und die inhibierende des Wasserdampfes deuten darauf hin, das der Natriumperoxydgehalt der Schmelze in den meisten Fallen entscheidend fur die Korrosionsgeschwindigkeit ist. Research on the corrosion of some metals and metal oxides in sodium hydroxide melts The investigations were aimed at contributing to the clarification of reactions encountered in the salt baths specially used for the descaling of high-alloyed chrome and chrome-nickel steels, particularly the Hooker bath. The investigations were carried out on the metals silver, gold, platinum, nickel and iron and on the metal oxides FeO, Fe3O4, Fe2O3 and Cr2O3 in NaoH melts at temperatures around 500°sC. Special attention was paid to the influence of the gas atmosphere on the corrosion rate. With the exception of silver, the corrosion of all the metals and oxides investigated is considerably more intense under oxygen than under nitrogen, and an admixture of water vapour has a strong corrosion inhibiting effect, especially under oxygen. Silver was found to be the only metal to show a higher corrosion rate in the presence of water vapour than under dry gases. The corrosion products were examined chemically, metallographically, and by means of X-ray and electron diffraction. The low corrosion rate under nitrogen shows that the reaction between metals or metal oxides and the NaOH melt takes place rather slowly, if at all. The accelerating effect of oxygen and the inhibiting effect of water vapour indicate that, in most cases, it is the sodium peroxide content of the melt which governs the corrosion rate.

Microstructure and area specific resistance of cathodic half cells for solid oxide fuel cells composed of perovskite-type cathodes and Co-alloy-coated ferritic stainless steel interconnects

Abstract: In order to prevent oxidation and Cr poisoning, a Co-W coating has been applied on ferritic stainless steel (FSS), which is used as the interconnect parts of solid oxide fuel cells (SOFCs). However, the electrical properties of the Co–W-coated stainless steels have not yet been evaluated. In this study, cathodic half-cells were experimentally manufactured with La0.8Sr0.2MnO3 (LSM) and La0.8Sr0.2Co0.8Fe0.2O3 (LSCF) as cathodes, and uncoated, Co-coated, and Co–W-coated FSSs as interconnects, respectively. Then their oxidation property and area-specific resistance (ASR) were evaluated at 800 °C. Based on phase identification and microstructural analysis, the Co–W-coating was confirmed to effectively suppress the Cr poisoning of the cathode. The ASR values of the Co–W-coated steel with LSM and LSCF as cathodes were 102 and 97 mΩ cm2, respectively, which are adequate for SOFC application. Furthermore, when the LSM was applied as a cathode material, the formation of Mn spinels enhanced the adherence between the cathode and interconnected parts. Thus, the combination of Co–W-coated FSS steel with LSM as the cathode material exhibited the optimal combination of electrical conductivity and microstructural stability. Graphic abstract.

Sulphur and nitrogen conversion from oxide to elemental form

Abstract: In SOx and NOx transformation into elementary S and N2 by sorption on (esp. coal-derived) solid or liq. sorbants, desorption at high temp. and opt. reduced pressure and then redn. of the oxides to the elements, the novelty is that (a) desorption is carried out by reducing gas passage through the sorbent; and (b) the SOx and NOx are electrochemically reduced in the gaseous phase to elementary S and N2 in a desorbent flow subjected to low temp. electric discharge.Adsorption is effected at 60-160 deg.C and desorption is effected at 200-500 deg.C. The reducing gas used for desorption is selected from natural gas, coke oven gas, H2, CO, methanol, methane and ammonia. The gas flow rates are 2-8 cu.m/kg sorbant/hr. Redn. is carried out in reactors equipped with low temp. electrical discharge generators.