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/Nm 3 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/Nm 3 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.

A strategy to reduce the impact of tar on a Ni ‐ YSZ anode of solid oxide fuel cells

“…Toluene vapour was introduced into H 2 by bubbling. The vapour pressure of toluene P Tol (mm Hg) at a given temperature was calculated using the Antoine equation, which is as following formulas and . Mass concentration of toluene vapour M Tol (g Nm −3 ) was obtained from volume fraction of toluene ν % (formula ).…”

“…Coke production results in the emission of coke oven gas (COG), a mixture of H 2 , CH 4 , and a small amount of unsaturated hydrocarbons. For every 500 million tons of coke that are produced, 210 billion cubic metres of COG are released as a by‐product . Since COG is rich in H 2 and CH 4 , it is a promising fuel with a specific heat in the range of 16 720 to 18 810 kJ m −3 .…”

“…For every 500 million tons of coke that are produced, 210 billion cubic metres of COG are released as a by-product. 1 Since COG is rich in H 2 and CH 4 , it is a promising fuel with a specific heat in the range of 16 720 to 18 810 kJ m −3 . In the past, COG was often used as a civil gas as a heat source after undergoing a series of cooling and purification processes, such as spraying with an ammonia solution to remove tar.…”

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

“…Usually, model tar compounds are used in these studies. Toluene is probably the most used model tar compound . However, also naphthalene and benzene are used.…”

High-Efficiency Biomass Gasifier SOFC Systems with Direct Internal Tar Reforming

“…Doyle et al observed carbon deposition with SEM-EDS analysis, but 20 g/Nm 3 toluene actually increased the cell performance by decreasing the cell ASR and increasing the amount of fuel available due to the tar reforming. Nonetheless, 32 g/Nm 3 dramatically affected the ASR (9). Other studies have used naphthalene (10)(11)(12) and benzene (13,14).…”