Dresden 2006 – wissenschaftliches Programm

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SYSS: Structure Formation and Self-Organization in non-equilibrium Systems

SYSS 1: Structure Formation and Self-Organization in non-equilibrium Systems I

SYSS 1.10: Vortrag

Donnerstag, 30. März 2006, 12:00–12:15, BAR Sch\"o

Spatio-temporal dynamics of a fuel cell reaction system: New oscillatory mechanism, bifurcation analysis and efficiency improvement — •Nilüfer Baba1, Jan Siegmeier1, Antoine Bonnefont2, and Katharina Krischer11Physik Department, E19, Technische Universität München, James Franck Str. 1, D - 85748 Garching bei München, Germany — 2Laboratoire d’Electrochimie et de Chimie Physique du Corps Solide, UMR - Université Louis Pasteur - C.N.R.S. 4, rue Blaise Pascal, 67000 Strasbourg, France

Fuel cells are promising energy conversion devices and much research effort is focussed on their improvement. One considerable problem is that the fuel gas (hydrogen) is contaminated by CO when produced from methane which constitutes the main H2 source. CO acts as a poison since it absorbs on the Pt catalyst, blocks hydrogen oxidation and reduces the efficiency.

We present a mathematical model for the H2/CO/Pt system and its bifurcation analysis. We demonstrate that the system displays a novel type of oscillations, involving a slow chemical autocatalysis of surface adsorbed species and a fast negative feedback loop involving the electric potential. The latter, however, is switched off in the presence of a high poison coverage, which enables potentiostatic oscillations in a wide parameter range. Simulations also show Turing patterns of small wavelengths. Based on these results we discuss control techniques that stabilize the system in a state where the coverage is minimized and thus the efficiency is enhanced.

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