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.

Investigation of mesoporous carbon hollow spheres as catalyst support in DMFC cathode

Abstract: In conventional low temperature PEM fuel cells, catalyst activity and stability rely on adequate structure and morphology of carbon support material, especially at the cathode that is exposed to high potential values. Degree of graphitization as well as pore distribution are decisive parameters for corrosion resistivity, catalyst utilization and mass transport. In this work, hollow graphitized carbon spheres (HGS) with mesoporous structure were tested as catalyst support in middle temperature (90–110 °C) direct methanol fuel cell (DMFC) cathode. Influence of catalyst loading and concentration as well as working temperature on power density was studied in a 5 cm 2 laboratory cell. Best results in terms of MEA performance were achieved with a catalyst loading of 2 mg Pt cm −2 at both electrodes and an extremely dense Pt concentration on carbon support of 50 and 40 wt% at the anode and cathode, respectively at 110 °C. Additionally, thermal pretreatment of carbon-supported catalyst up to 850 °C led to increase in particle size up to 7 nm and as a consequence to substantial higher ECSA retention during accelerated degradation test (ADT) under half-cell conditions.

Diffusion coatings for heat exchanger materials

Abstract: There is a need to develop cleaner electric power systems, with reduced emission of pollutants. This implies an increase in the maximum temperature of heat exchanger tubes, which is now, 600°C in modern power plants. For conventionally used ferritic steels, this increase is limited by the steels' mechanical properties and their corrosion resistance in coal, waste or biomass fired environments. Austenitic steels and nickel based alloys are potential candidates for increasing performance at higher temperature (700°C. Nonetheless, the corrosion resistance of these materials could be improved even further by applying a coating. Pack cementation is one of the easiest and cheapest coating processes. However, it requires a heating step which is presently performed at a minimum temperature of 750–800°C. The microstructure of the material may be significantly changed at these temperatures during the coating process, especially for ferritic–martensitic steels. Since the microstructure dictates the mechanica...