Chinese Journal of Catalysis ›› 2006, Vol. 27 ›› Issue (10): 857-862.

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Methanol Steam Reforming over CuZnAl CatalystsDerived from Hydrotalcite Precursor

TANG Ying, LIU Ye, LU Yong*, ZHU Ping, HE Mingyuan   

  1. Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, Shanghai 200062, China
  • Received:2006-10-25 Online:2006-10-25 Published:2010-11-28

Abstract: A series of CuZnAl composite oxide catalysts were prepared by calcination of the CuZnAl hydrotalcite precursor at various temperatures and used in the methanol steam reforming reaction. The catalyst calcined at 600 ℃ showed excellent activity and stability for the methanol steam reforming at 250 ℃ and WHSV of 2.5 h-1 with a H2O/CH3OH molar ratio of 1.3 as compared to those calcined at lower or higher temperatures. The results of thermogravimetry, X-ray diffraction, Fourier transform infrared spectroscopy, and temperature-programmed reduction revealed that CuZnAl hydrotalcite was almost completely decomposed at 600 ℃ to form nanosized CuO and the CuAl2O4 spinel phase that played a key role in separating and stabilizing the nanosized Cu and ZnO during the reaction. Increasing the calcination temperature to over 700 ℃ led to severe sintering of CuO and facilitated the formation of the CuAl2O4 spinel phase, causing a significant decrease in the number of active sites. With lower calcination temperatures (300[KG-45x]-[KG-20x]500 ℃), the hydrotalcite precursor was incompletely decomposed to form a (Cu,Zn)AlxOy(CO3)z composite and the associated CuAl2O4 spinel phase was not found. This resulted in the sintering of metallic Cu and ZnO as well during the reaction, thereby decreasing the catalyst activity.

Key words: copper oxide, zinc oxide, alumina, hydrotalcite, methanol, hydrogen, steam reforming, fuel cell