Effect of Sn loading variation on the electrochemical performance of dry internal reforming of biogas in solid oxide fuel cells

Solid Oxide Fuel Cells (SOFC) operations at 750 degrees C by using direct-biogas fuel without pre -reforming or steam addition on undoped Ni/YSZ and tin-doped Ni/YSZ (Sn-Ni/YSZ) anodes with varied Sn loadings were tested. High CH4/CO2 ratio (2:1) was used as simulated biogas with the absence of steam. The average current density of the undoped Ni/YSZ cells at 0.7 V and 750 degrees C was approximately 150 mA/cm2, while that of Sn-Ni/YSZ cells produced 300-420 mA/cm2 depending on Sn/Ni dopant concentration. Repeated cell tests revealed that the SOFC electrochemical performance is very sensitive to the quantity of Sn doped into the Ni/YSZ anode even with dopant amount as low as 0.10 wt% Sn/Ni. The highest elec-trochemical performance in H2 and biogas was obtained from Sn-Ni/YSZ with 0.38 wt% Sn/ Ni loading in the anode. The SEM micrographs of the tested anode surface showed no apparent sign of carbon deposition on the anode while small amount of carbon quantified on the SOFC tested cells with Temperature Programmed Oxidation (TPO). The successful operation of SOFC using biogas as fuel broadens the application of SOFC to directly produce electricity at places where biogas produced from anaerobic digestion of waste is available. However, due to the gradual degradation in the long durability test (150 h) shown in biogas there are further studies need to be carried out.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.