Thermodynamics of Dimethyl Ether Decomposition

Dimethyl Ether (DME) is an attractive energy source for on-board hydrogen generation as well as direct electro-oxidation in fuel cells. DME has physical properties similar to liquefied petroleum gas (LPG) and unlike methanol, it is non-toxic. Furthermore, DME is the simplest ether molecule, making it an interesting molecule for selectivity studies. Here we present a first principles, density functional theory, analysis of the thermodynamics of DME decomposition over transition metal catalysts (Re, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au). The most stable binding configurations and energies are determined for decomposition intermediates. From this, the most thermodynamically favorable decomposition pathway is determined for each of the transition metals studied. The electro-oxidation of DME at a polymer electrolyte membrane (PEM) fuel cell anode is explored using a simple electrochemical model [1, 2]. From the model we are able to determine efficient catalysts for fuel cell applications.

References

1. Nørskov, J. K.; Rossmeisl, J.; Logadottir, A.; Lindqvist, L.; Kitchin, J. R.; Bligaard, T.; Jonsson, H., Origin of the overpotential for oxygen reduction at a fuel-cell cathode. Journal of Physical Chemistry B 2004, 108 (46), 17886-17892.

2. Nilekar, A. U.; Mavrikakis, M., Improved oxygen reduction reactivity of platinum monolayers on transition metal surfaces. Surface Science 2008, 602 (14), L89-L94.