Coking suppression in solid oxide fuel cells operating on ethanol by applying pyridine as fuel additive

In this study, pyridine was used to suppress the coke formation in solid oxide fuel cells (SOFCs) operating on liquid fuels. Pyridine can selectively occupy acidic sites of the Ni/Al₂O₃ catalyst layer and solves the problem of dehydration of ethanol in principle, resulting in a significant reduction in the coke formation rate for operating on ethanol fuel. At 600 °C, by adding 12.5 vol.% pyridine into the ethanol fuel, the coke formation rate over the Ni/Al₂O₃ catalyst is reduced by 64% while a cell power output comparable to that operating on hydrogen is still achieved based on total potential hydrogen available from ethanol. The effective reduction of carbon deposition on the catalyst layer thus protects the anode layer from carbon deposition by strongly suppressing coke formation, especially near the anode-electrolyte interface. Pyridine is adsorbed onto the acidic sites of the Ni/Al₂O₃ catalyst and the adsorbed pyridine may reduce the amount of carbonium ions formed, thereby reducing coke formation. This study suggested that the addition of pyridine could suppress the coke formation in SOFCs with Ni/Al₂O₃ catalyst layer operated on ethanol or some other similar liquid fuels.