IngentaConnect Performance of Liquid Fuels in a Platinum-Ruthenium-Catalysed Pol...

Authors: Santasalo, Annukka; Kallio, Tanja; Kontturi, Kyösti

Source: Platinum Metals Review, Volume 53, Number 2, April 2009 , pp. 58-66(9)

Abstract:

Crossover and performance of different 1 M low molecular weight organic fuels with a platinum-ruthenium (60:40) catalyst in a unit fuel cell were studied at different temperatures. Large, negatively charged or complicated molecules were found to have the lowest crossover rates through the Nafion^® 115 membrane, and methanol had the highest permeability at all temperatures. The smallest molecule, formic acid, dissociates in water, resulting in a less severe crossover problem. In a PtRu-catalysed fuel cell, compounds with only one carbon atom exhibit superior performance compared to molecules having a carbon chain; with methanol and formaldehyde producing power densities up to five times higher than those achieved with molecules having a longer carbon chain. However, it should be noted that PtRu does not catalyse the breaking of the C-C bond; therefore, larger molecules can only be oxidised to derivative products. However, larger organic molecules show a lower rate of crossover through the Nafion^® membrane, which enables more concentrated solutions to be used to decrease the volume of the fuel. With the addition of a third metal to the PtRu-based catalyst, higher molecular weight molecules are good candidates for energy sources in a fuel cell.

Performance of Liquid Fuels in a Platinum-Ruthenium-Catalysed Polymer Electrolyte Fuel Cell