La1-xCexFe1-y-nCoyRunO3三效催化剂的结构表征及催化性能

用溶胶-凝胶法合成了La_1-xCe_xFe_1-y-nCo_yRu_nO₃(x,y=0.1～0.5,n=0.01～0.1)系列催化剂,XRD对晶体结构的表征发现,掺入Ru后基本结构未改变,但2θ值减小,晶胞参数变大.红外光谱分析表明,Ru改性的催化剂对应的特征峰位和峰形基本相似,但随着Ru掺杂量的增加,600cm^-1附近的谱带向高波数方向移动,n=0.01的样品,ν₁和ν₂向低波数方向移动,n=0.05样品的ν₁带出现最大吸收峰.XPS研究表明,掺杂Ru后Fe的外层电荷密度增大,并以多种价态存在;随着掺杂量的增加,表层中的Ce由与氧结合转变为与多羟基结合,其它氧种含量增加,催化活性增强.O₂-TPD结果表明,掺杂Ru使催化剂表面的吸附氧和晶格氧脱附温度降低,A离子空位增加.H₂-TPR研究表明,掺杂Ru使A离子空位增加,晶格氧活动性增强,催化活性提高;La_0.8Ce_0.2Fe_0.7Co_0.2Ru_0.1O₃的催化性能最佳.

Structural Characterization and Catalytic Properties of Three-way Catalyst La1-xCexFe1-y-nCoyRunO3

The La_1-xCe_xFe_1-y-nCo_yRu_nO₃(x,y=0.1-0.5, n=0.01-0.1) were synthesized by sol-gel method. The phase structures of the compounds do not change with Ru being doped, but 2θ decreases and crystal cell parameters increase determined by employing XRD technique. IR analysis show that the position and shape of adsorption peaks are almost the same in all compounds, except for the 600 cm^-1 peaks stretching to a high frequency and are changed in disorder with Ru content increasing. Comparing to unsubstituted samples, the band of sample with n=0.01 stretching to a higher region was observed with Ru being introduced into the compound, and the max adsorption peaks emerged in ν 1 when n=0.05, but the strength of peaks in ν 2 was very weak. The enhanced bond strength of Fe-O and Co-O could be attributed to the coordinative effect of Fe-O-Ru and Fe-O-Co, and also the deformation of Fe-O-Co structures. XPS testifies that Fe elements have many valences as the charge densities arise in the out layer. Ce combines with multihydroxy but not oxygen in the surface layer, meanwhile, the content of other oxygen species increased and catalytic activities improved. O₂-TPD results show that the temperature of adsorption oxygen and lattice oxygen decreased and the content of vacancy of oxygen increased. The catalytic activities are improved which is related to the A ion vacancies when x(Ce)≤0.2. H₂-TPR is in accordance with TPD in the result. The catalytic activities are improved which is related to the A ion vacancies and the enhancing lattice oxygen activities, and La_0.8Ce_0.2Fe_0.7Co_0.2Ru_0.1O₃ is the best one among all catalysts mentioned above.