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.

Corrosion testing of diffusion-coated steel in molten salt for concentrated solar power tower systems

Abstract: In the course of energy transition the development of sustainable technologies for power generation providing base load supply is of particular importance In comparison to photovoltaics concentrated solar power (CSP) Systems have great potential to fulfil this requirement by the use of thermal storage systems utilizing molten salt mixtures as heat transfer fluids For this purpose, molten nitrates are frequently discussed due to their beneficial thermal and physical properties as well as high operation temperatures In order to protect the piping system from degradation, coatings can be applied on the surface of the employed materials, which are commonly steels or Ni-based alloys The goal is to achieve cost reduction to ensure an even more competitive position of the CSP technology with respect to other renewable sources on the market In this study, the corrosion behavior of coated and uncoated ferritic-martensitic steels of type T91 and VM12 in molten salt (mixture of NaNO3 and KNO3) has been investigated under isothermal conditions The diffusion coatings are based on potentially protective elements such as Al, Si or Cr and were applied on the steels either by pack cementation or slurry deposition Characterization of the samples was conducted by means of optical microscope and EPMA in order to gain a deeper understanding of the occurring corrosion mechanisms and for the purpose of lifetime analysis

The corrosion behavior of several heat resistant materials in air + 2 vol-% Cl2 at 300 to 800 °C Part I - Fe-base and Fe-containing alloys

Abstract: In the present paper the corrosion behavior of 2 1 / 4 Cr1Mo steel, Alloys 800H, AC66, 45TM and 690 was investigated at 300 to 800 °C in dry air and synthetic air with 2 vol.-% Cl2. The data reveal that the major role determining corrosion resistance are played by Fe in the alloys. In particular if the same Cr-contents are present in the alloys it is only the Fe content which decides on resistance against Cl-attack while additions of even almost 3 % of Si evidently have only little effort. Das Korrosionsverhalten verschiedener hitzebestandiger Werkstoffe in Luft mit 2 % Cl2 bei Temperaturen von 300 bis 800 °C. Teil I – Fe-Basis- und Fe-haltige Legierungen In der vorliegenden Arbeit wurde das Korrosionsverhalten der Werkstoffe 10CrMo910, Alloy 800H, AC66, 45TM und 690 in trockener Luft und synthetischer Luft mit 2 % Cl2 bei Temperaturen von 300 bis 800 °C untersucht. Es zeigt sich, das die Korrosionsbestandigkeit der Werkstoffe in erster Linie durch den Fe-Gehalt der Legierungen bestimmt wird. Dies gilt insbesonders, wenn Werkstoffe mit gleichen Cr-Gehalten verglichen werden. Zusatze von fast 3 % Si schienen dagegen nur eine vergleichsweise geringe Wirkung zu besitzen.

Thermal polymerization of styrene — the formation of oligomers and intermediates, 1. Discontinuous polymerization up to high conversions

Abstract: During the thermal polymerization of styrene small quantities of dimeric and trimeric styrenes are formed which affect essential properties of the polymer. The kinetics of the oligomer formation are investigated under industrially important reaction conditions and the concentrations of the intermediates formed during the initiation reaction are determined by UV-spectroscopy. The results show that no gel effect occurs in the reactions investigated. Using the kinetic fomulae and reaction rate constants obtained it is possible to describe the formation of oligomers and intermediates at temperatures of 137°C and 180°C up to 97% monomer conversion. Bei der thermischen Polymerisation von Styrol entstehen in geringen Mengen dimere und trimere Styrole, welche wesentliche Eigenschaften des Polymeren beeinflussen. Die Kinetik der Oligomerenbildung wird bei technisch interessierenden Reaktionsbedingungen untersucht, und die Konzentrationen der bei der Startreaktion gebildeten Zwischenprodukte werden UV-spektroskopisch bestimmt. Die Ergebnisse zeigen, das bei den untersuchten Reaktionen kein Geleffekt auftritt. Mit den erhaltenen kinetischen Gleichungen und Reaktionsgeschwindigkeitskonstanten kann die Bildung der Oligomeren und der Zwischenprodukte bei Temperaturen von 137°C und 180°C bis zu Monomerumsatzen von 97% beschrieben werden.

Coupling of electrochemical and optical measurements in a microtiter plate for the fast development of electro enzymatic processes with P450s

Abstract: Electro enzymatic processes offer novel opportunities in catalysis by combining advantages of enzyme catalysis and electrochemistry. An efficient electrochemical cofactor substitution system can help to overcome economical hurdles for the technical use of cofactor dependent enzymes. The in vitro biocatalysis with P450 BM-3 was investigated aiming for the substitution of the expensive natural cofactor NADPH by electrochemistry as “electron source”. An electrochemical 24-well microtiter plate (eMTP) was developed, which can be employed in a standard microtiter plate reader and enables parallelized electrochemical experiments in combination with simultaneous optical measurements. The eMTP was applied to screen a P450 monooxygenase BM-3 mutein library and determine the behavior of P450 BM-3 muteins in an electrochemically driven surrogate assay with the mediator cobalt sepulchrate. Besides determining reaction rates also the influence of single reaction parameters e.g. applied potential, enzyme and mediator concentration were measured. Additionally the developed eMTP based screening system allows a fast development of an electro enzymatic process.

Nutzung nachwachsender Rohstoffe in der industriellen Stoffproduktion

Abstract: Nachwachsende Rohstoffe werden in der Zukunft auch in der chemischen Industrie immer grosere Bedeutung erlangen. Im Kontext der Weisen Biotechnologie stellen sie den Schnittpunkt zwischen der Landwirtschaft und der chemischen Industrie dar. Durch die Verknappung und durch die damit verbundene Verteuerung der fossilen Rohstoffe stellen die nachwachsenden Rohstoffe eine interessante Alternative dar. Betrachtet man die Produktion von Bulk-Chemikalien, so wird deutlich, dass fur diesen Bereich neben den C-Quellen Zucker und Starke neue Rohstoffquellen erschlossen werden mussen. Hier bietet sich die Nutzung von Lignocellulose an. Verbunden mit der stofflichen sollte es aber auch eine energetische Nutzung geben. In diesem Beitrag werden diese interessanten Zukunftsfelder diskutiert – insbesondere auch aus der Sicht der Industrie.