改进溶胶-凝胶法合成CeO2-ZrO2固溶体及催化性能研究
收稿日期: 2009-12-15
修回日期: 2010-02-06
网络出版日期: 2010-07-19
基金资助
国家自然科学基金(20976057); NSFC-广东联合基金(U0834004)
Study on Catalytic Properties of Nano-CeO2-ZrO2 Mixed Oxides Prepared by Modified Sol-Gel Method
Received date: 2009-12-15
Revised date: 2010-02-06
Online published: 2010-07-19
以Ce(NO3)3·6H2O和ZrO(NO3)2·2H2O为原料采用改进溶胶-凝胶法合成了纳米级铈锆固溶体, 考察了不同铈锆摩尔比和温度条件对制备固溶体的粒度、晶型和还原性能的影响, 获得了优化工艺条件. 采用XRD、比表面积测定(BET)、扫描电子显微镜(SEM)、程序升温还原(TPR)进行表征. 结果表明: 此方法制备的固溶体均为立方萤石结构的铈锆固溶体复合氧化物, 其比表面积可达92m2/g; 450℃焙烧制备的样品具有良好的还原活性. 在常压固定床流动体系中进行乙醇水蒸气重整反应结果表明: 当n(Ce):n(Zr)=3:1时, CeO2-ZrO2固溶体比CeO2和其它比例的固溶体具有更高的催化活性和对氢气的选择性. ZrO2的引入不但改进了CeO2的热稳定性, 而且提高了CeO2的还原能力.
关键词： 氢气; 乙醇水蒸气重整反应; 纳米CeO2-ZrO2; 改进溶胶-凝胶法
袁文辉, 周辰辰, 李 莉 . 改进溶胶-凝胶法合成CeO2-ZrO2固溶体及催化性能研究[J]. 无机材料学报, 2010 , 25(8) : 820 -824 . DOI: 10.3724/SP.J.1077.2010.00820
The nanosized CeO2-ZrO2 solid solutions were prepared by modified Sol-Gel method with Ce(NO3)3·6H2O and ZrO(NO3)2·2H2O as starting materials. The effects of different Ce/Zr molar ratio and calcination temperature on the particle size, crystal type and reducibility were studied to obtain optimal preparation condition. CeO2-ZrO2 solid solution was characterized by XRD, SEM and TPR measurements. Results show that the highest specific surface area of CeO2-ZrO2 solid solution is 92m2/g while Ce/Zr molar ratio is 3: 1. CeO2-ZrO2 solid solution prepared by modified Sol-Gel method is fluorite structured. TPR results show that CeO2-ZrO2 solid solution calcined at 450℃ has good catalytic reducibility. Catalytic properties are estimated through a fix-bed reactor under atmospheric pressure. CeO2-ZrO2 solid solution with Ce/Zr molar ratio of 3: 1 show higher catalytic activity and selectivity to ethanol steam reforming reaction than those of CeO2 and other molar ratio CeO2-ZrO2 solid solution. Both reducibility and heat stability of CeO2 can be improved with the addition of ZrO2.
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