DETERIORATION MECHANISM OF DIRECT INTERNAL REFORMING CATALYST

The deterioration mechanism of reforming catalysts used for internal r eforming molten carbonate fuel cells is studied through post-test anal yses of the used catalysts. The catalysts studied are Ni/MgO-Al2O3. De activation of the catalysts is caused both by a decrease in Ni surface area of the catalyst and by loss of specific activity of the Ni surfa ce (alkali poisoning). The decrease in Ni surface area is characterize d firstly by accelerated sintering of Ni particles due to the existenc e of alkali metals (attached electrolyte). Secondly, sulfur poisoning also plays an important role, especially for sintered catalysts with s mall Ni surface areas. As for the effect of alkali poisoning, the spec ific activity of the Ni surface decreases to 15-60% of the original on e, Blockage of pore structure by the electrolyte does not seem to he i mportant for the loss of Ni surface area.