溶胶凝胶法制备CexCo2-xAlO4复合氧化物及其催化分解N2O(英文)

Catalytic Decomposition of N_2O over Ce_xCo_(2- x)AlO_4 Composite Oxides Prepared by Sol-gel Method

用柠檬酸-溶胶凝胶法制备了CexCo2-xAlO4系列复合氧化物和K2CO3改性催化剂,考察了复合氧化物组成、母液p H值、钾负载量对N2O分解催化剂活性的影响,用N2物理吸附、X射线衍射(XRD)、扫描电镜(SEM)、H2程序升温还原(H2-TPR)、O2程序升温脱附(O2-TPD)、X射线光电子能谱(XPS)等方法表征了催化剂结构.结果表明:用Ce取代Co2AlO4中部分Co制得的CexCo2-xAlO4复合氧化物催化活性有所提高,其中母液p H=2、组成为Ce0.05Co1.95AlO4的催化剂活性较高,该催化剂具有较高的比表面积、较小的晶粒及Ce-Co间的协同效应;进一步研究表明,由于K粒子的电子效应,使得0.05 K/Ce0.05Co1.95AlO4的催化活性又优于其他催化剂,有氧气氛中450℃连续反应50 h,N2O分解率达98.5%.

A series of CexCo2- xAlO4 composite oxides were prepared by citric acid based sol-gel method and further modified by K2CO3. The effect of composite oxide compositions,p H values of mother liquid,and potassium loadings on catalytic activity for N2 O decomposition was investigated. The bare and K-modified CexCo2- xAlO4 catalysts were characterized by means of nitrogen physisorption,X-ray diffraction（ XRD）,scanning electron microscopy（ SEM）,hydrogen temperature-programmed reduction（ H2-TPR）,temperature-programmed desorption of oxygen（ O2-TPD）,and X-ray photoelectron spectroscopy（ XPS）techniques. The results show that the catalytic activity of CexCo2- xAlO4 composite oxides was enhanced in comparison with Co2 AlO4,and the optimal composition was Ce0. 05Co1. 95 AlO4with larger surface area,smaller particle size and the Ce-Co synergistic effect. Further results indicate that 0. 05 K / Ce0. 05Co1. 95 AlO4catalyst due to the electronic effect of potassium on c obalt oxides was more active than other catalysts,over which N2 O conversion reached 98. 5% at 450 ℃ after 50 h continuous reaction in the presence of oxygen.