摘要
用溶胶 -凝胶法合成了 La1 - x Cex Fe1 - y - n Coy Run O3( x,y=0 .1～ 0 .5 ,n=0 .0 1～ 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 2 θ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 ,60 0 cm- 1 附近的谱带向高波数方向移动 ,n=0 .0 1的样品 ,ν1 和 ν2 向低波数方向移动 ,n=0 .0 5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 ;La0 .8Ce0 .2 Fe0 .7Co0 .2 Ru0 .1 O3的催化性能最佳 .
The La 1-xCe xFe 1-y-nCo yRu nO 3(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. O 2-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. H 2-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 0.2Ru0.1O3 is the best one among all catalysts mentioned above.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2004年第9期1679-1683,共5页
Chemical Journal of Chinese Universities
基金
国家自然科学基金 (批准号 :2 0 2 710 19)
黑龙江省自然科学基金 (批准号 :B0 0 -0 6)
黑龙江大学杰出青年科学基金 (批准号 :JC-2 0 0 0 -2 )资助
关键词
三效催化剂
结构表征
催化净化
Three-way catalyst
Structural characterization
Catalytic purification
