Clean and stable conversion of oxygen-bearing low-concentration coal mine gas by solid oxide fuel cells with an additional reforming layer

Abstract

Direct power generation using low-concentration coal mine gas (LC-CMG, < 30% CH4) by solid oxide fuel cells (SOFCs) is an attractive approach for the clean and efficient utilization of abundant LC-CMG resources. In this study, Ni–Fe alloy catalyst from in situ decomposition of NiFe2O4 oxide is used to promote the electrochemical performance, efficiency and robustness of SOFCs using simulated LC-CMG as fuel. The modified SOFC is fed with humidified H2 and CH4–N2 in sequence and exhibits high electrochemical performance. There is only a slight performance drop from 783 to 660 mW cm−2 when adding O2 in humidified CH4–N2 fuel. The operation of all cells with different concentrations of LC-CMG is quite stable during over 100-h tests and no coking is found on the entire anode and Ni–Fe alloy catalyst, suggesting the cell with superior resistance to coking. Besides, a heterogeneous reaction model is established to reveal the anti-carbon effect of the Ni–Fe catalyst. Our findings indicate the great application potential of direct power generation from LC-CMG by SOFCs with an additional reforming layer.