Effect of H₂S and HCl on solid oxide fuel cells fed with simulated biosyngas containing primary tar

Abstract

Integrated biomass gasifier solid oxide fuel cell systems are an alternative to fossil-fuel-based combined heat and power generators. However, biosyngas contaminants represent a bottleneck for small-scale systems. In this work, we present the results of experiments on the effects of H₂S, HCl, and acetic acid as model primary tar on Ni-GDC SOFC. First, the effects of 17-128 g/Nm³ dry basis acetic acid were studied. On a second cell, 0.8 and 1.3 ppm(v) H₂S were added to the simulated biosyngas anode flow. After a full recovery, the cell was exposed to 42 g/Nm³ acetic acid and 0.8 ppm(v) H₂S. On a third cell, 3.4, 20, and 50 ppm(v) HCl were tested and, after a recovery period, 42 g/Nm³ acetic acid and HCl were added. Even 0.8 ppm(v) H₂S caused an immediate voltage drop. H₂S affected CH₄ reforming and water-gas shift reaction. Differently, even 50 ppm(v) HCl appeared not to significantly affect these reactions. Acetic acid increased the cell voltage but caused carbon deposition at the cell inlet. The voltage increase seemed not to be affected by H₂S or HCl, and no acetic acid was measured at the cell outlet, indicating that these contaminants do not affect the primary tar conversion.