Improvement of solid oxide fuel cell performance by a core-shell structured catalyst using low concentration coal bed methane fuel

A core-shell structured catalyst Ni-BaO-CeO₂@SiO₂ (@NBC; 7.87% Ni content) with high catalytic activity and thermal stability is prepared and utilized for partial oxidation of methane. The catalyst is introduced into the Ni-8 mol% Y-stabilized ZrO₂ anode of a conventional solid oxide fuel cell (CC) by direct spraying (denoted as P-@NBC//CC) and indirect loading as an independent catalyst layer (denoted as Y-@NBC//CC) to improve the coking resistance and cell stability when low concentration coal bed methane is used. At 800°C, the maximum power density of P-@NBC//CC and Y-@NBC//CC increases by ~26.8% and 32.8%, respectively, over that of CC (0.63 W cm⁻²). At a discharge current of 0.16 A at 800°C, the voltage of CC drops to 0 V after 16 hours. In contrast, the voltage of P-@NBC//CC decreases from 0.8 to 0.6 V within 30 hours, and that of Y-@NBC//CC decreases from 0.8 to 0.7 V over 180 hours. The manner of loading of the catalyst layer has a significant effect on the cell stability. The indirect loading mode as an independent catalyst layer has an advantage over the direct spraying method. The postmortem microstructure of the cell reveals that direct spray loading on the anode surface allows the catalyst particles to penetrate into the anode layer and blocks the anode pores, resulting in a lower porosity and higher diffusion resistance.