钙钛石型复合氧化物催化剂LaMn_yCo_(1-y)O_3催化性能的研究 Ⅱ.过渡金属离子之间的相互作用与在氨氧化反应中的催化性能  

A Study of the Catalytic Properties of Perovskite-type Oxides LaMn_yCo_(1-y)O_3 Ⅱ. The Interaction between Transition Metal Ions and Their Catalytic Property in Ammonia Oxidation

作　　者：刘社田[1] 于作龙[1] 吴越[1] 

机构地区：[1]中国科学院长春应用化学研究所

出　　处：《化学学报》1994年第11期1076-1081,共6页Acta Chimica Sinica

基　　金：国家自然科学基金资助课题.

摘　　要：发现钙钛石型复合氧化物LaMnyCo_(1-y)O_3中B位过渡金属离子Mn,Co之间的相互作用及其氧化还原性能是影响氨氧化反应中NO选择性的重要因素.B位少量掺杂可促进过渡金属离子的氧化还原性,但B位组成相当时时(y=0.5),则不利于它们的氧化还原.富锰区(y>0.5),Mn^(3+)-O^(2-)-Mn^(4+)的超交换作用对样品的磁性及NO选择性起决定作用,富钴区(y<0.5),Co^(2+)和Co~Ⅲ离子的存在及其浓度是影响NO选择性的主要因素.y=0.5时样品的结构决定了样品的强铁磁性质,并由于Mn^(3+)-O^(2-)-Co^(3+)之间不易氧化还原因而对生成NO不利.It has been found that the interaction between the two transition metal Mn, Co ions on B-site and their Redox property are the important factors influencing the NO-selectivity in ammonia oxidation. The NO-selectivity is related to the redox ability of Mn3+→Mn4+ or Co2+→Co3+, which could be promoted by doping a small amount of foreign transition metal ions on B-site of matrix samples, but not for the sample with the composition of y = 0.5. In Mn-rich region (y>0.5), the magnetic property and NO-selectivity are controlled by the ferromagnetic superexchange of Mn3+-O2--Mn4+. The main factor influencing the NO-selectivity of Co-rich samples (y<0.5) is the concentration of Co2+ and CoⅢ ions. The strong ferromagnetism of the sample with the composition of y = 0.5 may be due to its crystal structure, and the redox between Mn3+ and Co3+ is unfavorable for the producing of NO. There exists a close relationship between the NO-selectivity and the valence, d-electron configuration, electron transmission rate and the interaction between the electrons.

关 键 词：钙钛石 复合氧化物 催化剂 催化性 

分 类 号：O643.36[理学—物理化学]