SOFC single cells fed by biogas: Experimental tests with trace contaminants

摘要

Highlights•The impact of biogas trace compounds on SOFC performance was investigated.•Cell performance were experimentally evaluated considering the impact of H2S, HCl and D4.•D4 affect the SOFC performance already at 111 ppbv.•The threshold limit for H2S was around 2 ppmv and 40 ppmv for HCl.AbstractBiogas from biological treatments and from the waste degradation in landfills generally contains a wide range of trace impurities (e.g., sulphur compounds, siloxanes, halogens, tar compounds, etc.). This paper describes an experimental analysis performed with SOFC single cells fed by a synthetic gas polluted by H2S, HCl, D4 and a mixture of H2S + C2Cl4. The aim is to detect the threshold tolerance limit on different cell performance parameters. Results show how: hydrogen sulphide has a strong impact on the polarization losses due to the nickel sulphide formation on the electrode that causes a mass transfer resistance. Hydrogen chloride particularly limited the electrochemical processes. Octamethylcyclotetrasiloxane (D4) showed a high impact on SOFC performance even at ultra-low level (78–178 ppb(v)) as a consequence of the formation of silicon dioxide covering the anode porous sites. Sulphur added to C2Cl4, accelerated the deterioration of SOFC performance. In addition, current density variations and operating temperature are studied during sulphur poisoning. An opposite behaviour on SOFC performance was revealed by operating temperature and current density.