(82e) Hydrogen Purification Using Microstructures

The preparation and optimization of catalysts for the water gas shift reaction in micro channel reactor were investigated with the aim to generate hydrogen for mobile fuel cell systems. The catalysts have to exhibit high catalytic activity and strong adhesion to support foils and prove long therm stability, especially during start-up/shut-down procedures. The coating of micro channel metallic plates was performed with nanopowders/support materials such as Al2O3 and CeO2 by wash coating and spin coating methods. The dispersion stability and the detailed interaction between alumina and cerium dioxide particles were determined by zeta-potential analysis. The knowledge of zeta-potential allowed to control the flocculation and dispersion stages for solid medium in the suspension. The zeta-potential was measured for both slurries as a function of pH. Their maximum stability was reached at pH of 2 and 8 respectively. The addition of PVA-binders with different moleculare weight and concentration in the suspension influenced the particle diameter changes of solid materials. A small amount of surfactant was added in to the slurry and increased particle dispersion. The highest resulting Al2O3 surface reached 216.4 m2/g. The catalytic active materials (Pt on CeO2 and Pt/CeO2 on Al2O3) were deposited during the impregnation method and accomplished the forming of the two catalyst systems. Well-adhering wash coats have been obtained on micro structured foils. A detailed investigation on the influence of different variables on the coating uniformity has led to a coating of catalysts inside stainless steel micro channels with good adhesion. The adhesion was highly depending on the nature of binder, initial particle sizes, pH and also surfactant addition.