Thermodynamics of sulfur poisoning in solid oxide fuel cells revisited: The effect of H2S concentration, temperature, current density and fuel utilization

JOURNAL OF POWER SOURCES

卷:296

Article

da Silva, Aline Lima¹  Heck, Nestor Cezar¹ 

[1] Univ Fed Rio Grande do Sul, Program Postgrad Studies Min Met & Mat Engn PPGE3, Computat Thermodynam Met & Mat NTCm Res Grp, Ctr Tecnol, BR-91501970 Porto Alegre, RS, Brazil

关键词: Thermodynamics;    Methane;    Internal reforming;    Sulfur tolerance;    Solid oxide fuel cells;   

DOI  :  10.1016/j.jpowsour.2015.07.046

来源: Elsevier

【 摘 要 】

Thermodynamics of sulfur poisoning in SOFCs is revisited in the present study, aiming at contributing to the understanding of the effects of different operating parameters on deactivation by sulfur. Ni-S Gibbs energy diagram shows that, whenever sulfur chemical potential is increased, the catalyst poisoning becomes greater, due to increase in nickel sulfide activity, which is a strictly increasing function of sulfur coverage on Ni surface. For studying current density effect, simulations are carried out in the range of 0 (OCV) - 1 A cm(-2), at 1123 K, considering methane as a fuel. At 10 ppm H2S, an increase in current density from 0 (OCV) to 0.5 A cm(-2) results in a slight increase in the nickel sulfide activity from 3.0 x 10(-6) to 1.2 x 10(-5); however, at 1 A cm-2, nickel sulfide activity is 25.000 times higher than at 0.5 A cm(-2). At 1 A cm(-2), H-2 and CO are almost entirely converted to H2O and CO2 by electrochemical reaction. Therefore, the effect of current density becomes remarkable when fuel utilization approaches 100%. These theoretical findings are corroborated by the recent experimental evidences related to the detrimental influence of current density on SOFC performance during sulfur poisoning. (C) 2015 Elsevier B.V. All rights reserved.

【 授权许可】

Free