Tolerance tests of H 2S-laden biogas fuel on solid oxide fuel cells

Abstract

Biogas is a variable mixture of methane, carbon dioxide and other gases. It is a renewable resource which comes from numerous sources of plant and animal matter. Ni–YSZ anode-supported solid oxide fuel cell (SOFC) can directly use clean synthesized biogas as fuel. However, trace impurities, such as H 2S, Cl 2 and F 2 in real biogas can cause degradation in cell performance. In this research, both uncoated and coated Ni–YSZ anode-supported cells were exposed to three different compositions of synthesized biogases (syn-biogas) with 20 ppm H 2S under a constant current load at 750–850 °C and their performance was evaluated periodically using standard electrochemical methods. Postmortem analysis of the SOFC anode was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results show that H 2S causes severe electrochemical degradation of the cell when operating on biogas, leading to both complete electrochemical and mechanical failure. The Ni–CeO 2 coated cell showed excellent stability during CH 4 reforming and some tolerance to H 2S contamination.