Structural Characteristics of (NiMgAl)O{sub}x Prepared from a Layered Double Hydroxide Precursor and its Application in Direct Internal Reforming Molten Carbonate Fuel Cells

摘要

(NiMgAl)O{sub}x materials prepared from layered double hydroxide (LDH) precursors show a typical mesoporous structure with an average pore size of about 6 nm, excellent activity for the methane steam reforming (MSR) reaction at 650 ℃, and a strong resistance against Li poisoning, suggesting the possibility for future application in direct internal reforming molten carbonate fuel cells (DIR-MCFC). X-ray diffraction (XRD) experiments indicate that the molar ratio of Al/Mg exerts a strong effect on the properties of both the LDH precursors and final catalysts. Temperature-programmed reduction (TPR) analysis reveals that the Al/Mg molar ratio influences the properties of Ni in the final catalyst. The catalytic performance of the catalysts prepared is greatly influenced by the molar ratio of Al/Mg for MSR. The activity gradually increases with an increase in the Al/Mg ratio (0.14-1.5). However, with further increases in the amount of Al added (Al/Mg = 2), the activity decreases. The activity is strongly related to the BET surface area and Ni dispersion. The Li-poisoning test proves that Mg-rich catalysts lose their activity quickly upon exposure to Li, while Al-rich catalysts maintain virtually all of their original activity. NiMgAl (Al/Mg = 1.5) is found to be an excellent catalyst for the DIR-MCFC, having both the highest activity and strongest resistance against Li poisoning.