The effect of synthesis gas composition on the performance of Ni-based solid oxide fuel cells

• Operation of Ni-based SOFC with simulated syngas of varying H2:CO ratio.
• H2:CO ratio selected to represent C1 to C4 reforming products.
• Increasing CO concentration decreased cell power only when using low flow rates.
• Decreased power at low flow attributed to carbon deposition on Ni catalyst.
• Carbon balance showed losses >2% only for high CO concentration with low flow rates.

An increased interest in using hydrocarbons in solid oxide fuel cells for the production of power has led to research into operation on synthesis (syn) gas, a mixture of hydrogen and carbon monoxide. Hydrocarbons are typically reformed, either internally or in an external reformer prior to the fuel cell, producing syngas with various H2:CO ratios depending on the hydrocarbon used. This paper examines the effect of varying the H2:CO ratio with respect to C1 to C4 steam reforming reactions and additionally a mixture containing a higher ratio of carbon monoxide. It was found that there was no significant relationship between cell performance and H2:CO ratio when a high feed rate was employed. For low flow rates, however, the high carbon monoxide concentration resulted in a significant decrease in cell performance. It was determined that this was caused by reversible carbon deposition as opposed to a decrease in carbon monoxide reactivity.

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