Hydrogen production from ethanol steam reforming in a solid oxide fuel cell (sofc) - a theoretical analysis of the system efficiency

Resumo

In SOFC, high operative temperature allows the direct conversion of ethanol into H2 to take place in the electrochemical cell. Direct internal reforming of ethanol, however, can produce undesirable products that diminish system efficiency and, in the case of carbon deposition over the anode, massive forces within the electrode structure lead to its rapid breakdown. In this context, a thermodynamic analysis is fundamental to predict the product distribution as well as the conditions favorable for carbon to precipitate inside the cell. Hence, the aim of this work is to find appropriate ranges for operating conditions where carbon deposition in SOFC is not feasible. The effects of hydrogen consumption on anode components and on carbon formation are investigated. Equilibrium determinations are performed by the Gibbs energy minimization method. The effect of the type of solid electrolyte (oxygen-conducting and hydrogen-conducting) on carbon formation is also investigated. A new approach to model the direct internal steam reforming of ethanol in SOFC is presented. Theoretical SOFC (oxygen-conducting) efficiencies are accomplished in the region where carbon formation is thermodynamically impossible. The results of this work are consistent with previous results from literature.