Abstract
Biogas is a renewable resource which comes from numerous sources, such as biomass, manure, sewage, municipal waste, green waste and energy crops. It is a variable mixture of CH4, CO2, N2 and other gases. Ni-YSZ cermet is commonly used as the anode of a solid oxide fuel cell (SOFC) because it has excellent electrochemical performance and is cost effective. It can utilize not only hydrogen fuel, but also a clean synthesized biogas mixture of varying CH4 and CO2 concentrations with steam (H2O) and air (O2). However, trace impurities, such as H2S, Cl2, and F2 in biogas may cause degradation of cell performance. In this work, Ni-CeO2 coated Ni-YSZ anode-supported cells were exposed to two different compositions of synthesized biogases (biogas) with 100 ppm Cl2 under a constant current load at 850°C. The electrochemical performance was evaluated periodically using standard electrochemical methods. 20 ppm H2S impurity was also added to the fuel stream during the Cl2 impurity testing and its effect was noted. Post-mortem analyses of the SOFC anode were performed using XRD, SEM and XPS. The results show that Cl2 did not cause any electrochemical degradation of the cell during the 200 h test. However, after adding 20 ppm H2S, the cell started to degrade and eventually lost all its performance. The experimental data showed that 100 ppm Cl2 impurity in the fuel gas can postpone the degradation caused by addition of the H2S impurity.
Published Version
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