DIR-MCFCにおける改質触媒劣化現象に関する研究 A Study on Degradation Phenomena of Reforming Catalyst in DIR-MCFC

燃料電池の中でも特に高効率発電の期待できる直接内部改質方式溶融炭酸塩型燃料電池 (DIR-MCFC) の検討を行い, 特に劣化原因の検討を行った.その結果, DIR-MCFCにおいて初期特性は, 外部改質方式溶融炭酸塩型燃料電池 (ER-MCFC) 同等の特性が得られ内部改質運転の可能なことが実証できた.また, DIR-MCFCはER-MCFCと比較し特性低下が大きくその原因としては, 炭酸塩による触媒被毒が主原因であることが分かった.さらに, 触媒被毒は燃料ガス入口部で大きく, 炭酸カリウムによる被毒の大きいことが分かった.炭酸塩による被毒を防止するため, アノードガスチャンネルのコルゲート板 (インコネル600) にニッケルメッキを施したところ, DIR-MCFCにおいて炭酸塩による触媒被毒が大幅に低減でき, 寿命特性を向上できることを見いだした.

Degradation phenomena of a reforming catalyst in a direct internal reforming molten carbonate fuel cell (DIR-MCFC), which holds promise for the highest efficiency among several types of fuel cells, were investigated. The initial performance of the DIR-MCFC was the same as that of an external reforming molten carbonate fuel cell (ER-MCFC), but the degradation rate of cell performance was greater than that of an ER-MCFC. It was found that catalyst deactivation due to electrolyte poisoning was the main reason for the high degradation rate. Electrolyte poisoning mainly occurred at the fuel gas inlet through liquid phase poisoning. Ni plating on the Inconel 600 corrugated current collector in the anode gas channel was tested in order to prevent electrolyte poisoning. It was found that Ni plating was effective to improve DIR-MCFC life characteristics by its contact angle to the molten carbonate electrolyte.