A highly active Ni-Al2O3 catalyst prepared by homogeneous precipitation using urea for internal reforming in a molten carbonate fuel cell (MCFC): Effect of the synthesis temperature

Ni-Al2O3 catalysts for use in internal reforming in a molten carbonate fuel cell (MCFC) were prepared by homogeneous precipitation method at various synthesis temperatures. The effects of synthesis temperature on physicochemical properties and catalytic activities of the Ni-Al2O3 catalysts were investigated. XRD measurements exhibited that the peak intensity of NiAl2O4 in the calcined catalysts increased with higher synthesis temperatures. TPR measurements demonstrated that reduction peaks appeared around 670-680 degrees C for every synthesis temperature, indicating that the Ni particles interacted strongly with the support. Hydrogen chemisorption results showed that nickel dispersion and nickel surface area decreased in the order: K52_80C > K52_85C > K52_90C > K52_95C > K52_100C. TEM images of the reduced Ni-Al2O3 catalysts revealed that the average sizes of Ni particles were 13.1, 13.4 and 15.9 nm for K52_80C, K52_90C and K52_100C, respectively, which means that a higher synthesis temperature yielded a larger Ni particle. The performance of the catalysts in methane steam reforming showed that catalysts prepared at the lowest synthesis temperature (80 degrees C) exhibited the highest reaction rate. These results suggest that a lower synthesis temperature is favorable to prepare highly active Ni-Al2O3 catalysts by the homogeneous precipitation method. (C) 2010 Published by Elsevier Ltd on behalf of Professor T. Nejat Veziroglu.