Investigating the impact and reaction pathway of toluene on a SOFC running on syngas

Abstract

The integration of solid oxide fuel cells (SOFCs) with gasification systems have theoretically been shown to have a great potential to provide highly efficient distributed generation energy systems that can be fuelled by biomass including municipal solid waste. The syngas produced from the gasification of carbonaceous material is rich in hydrogen, carbon monoxide and methane that can fuel SOFCs. However, other constituents such as tar can cause catalyst deactivation, and blockage of the diffusion pathways. This work examines the impact of increasing concentrations of toluene as a model tar in a typical syngas composition fed to a NiO-GDC/TZ3Y/8YSZ/LSM-LSM SOFC membrane electrode assembly operating at 850°C and atmospheric pressure. Results suggest that up to 20 g/Nm3 of toluene and a low fuel utilisation factor (c.a. 17%) does not negatively impact cell performance and rather acts to increase the available hydrogen by undergoing reformation. At these conditions carbon deposition does occur, detected through EDS analysis, but serves to decrease the ASR rather than degrade the cell. Alternatively, the cell operating with 32 g/Nm3 toluene and with a fuel utilisation of 66.7% is dramatically affected through increased ASR which is assumed to be caused by increased carbon deposition. In order to test for the presence of tar products at the anode exhaust samples have been captured using an absorbing filter with results from HS-GC/MS analysis showing the presence of toluene only. © 2014 Hydrogen Energy Publications, LLC.