催化学报

催化学报 ›› 2006, Vol. 27 ›› Issue (10): 857-862.

• 研究论文 • 上一篇    下一篇

CuZnAl水滑石衍生催化剂上甲醇水蒸气重整制氢Ⅰ. 催化剂焙烧温度的影响

汤颖,刘晔,路勇,朱萍,何鸣元   

  1. 华东师范大学化学系, 上海市绿色化学与化工过程绿色化重点实验室, 上海 200062
  • 收稿日期:2006-10-25 出版日期:2006-10-25 发布日期:2010-11-28

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

PDF

790

被引次数

107

摘要： 以类层柱CuZnAl水滑石为前体,经不同温度焙烧制备了一系列甲醇水蒸气重整制氢催化剂. 在250 ℃、 水/甲醇比1.3和重时空速2.5 h-1下的反应结果表明, 600 ℃焙烧的催化剂具有优异的活性和稳定性,而≤500 ℃和≥700 ℃焙烧后的催化剂活性较差. 热重、 X射线衍射、 傅里叶变换红外光谱和程序升温还原分析结果表明, 600 ℃焙烧时水滑石分解较为完全,析出纳米CuO粒子的同时伴生CuAl2O4尖晶石相,进而在反应过程中对金属Cu纳米粒子和ZnO起到良好的隔离和稳定作用. 焙烧温度≥700 ℃时CuO纳米粒子发生二次团聚,同时CuAl2O4尖晶石相大量生成,造成催化活性位减少,活性较低; 而焙烧温度≤500 ℃时水滑石分解不完全,生成 (Cu,Zn)AlxOy(CO3)z复合物且无尖晶石相伴生,造成反应中金属Cu纳米粒子和ZnO聚集,导致催化剂活性较低.

关键词: 氧化铜, 氧化锌, 氧化铝, 水滑石, 甲醇, 氢, 水蒸气重整, 燃料电池

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