La-Mn-Ni-O催化剂组成、结构、还原性能及氧化活性

CORRELATION OF COMPOSITION、CRYSTAL STRUCTURE、REDUCIBILITY AND CATALYTIC OXIDATION ACTIVITY ON La-Mn-Ni-O SYSTEM

用硝酸盐分解法合成了LaMn_(1-x)Ni_xO_3(0≤2≤1.0),研究了组成、晶体结构及其与还原性能、CO和CH_3OH催化氧化活性的关系。XRD证实在0.0≤x≤1.0范围内,本体系都生成单一钙钛矿结构:0.0≤x≤0.4,0.8<x≤1.0时属菱形晶系;0.5≤x≤0.8为立方晶系。同时x=0.4和0.8附近正好是菱形→立方及立方→菱形的晶型转变区。IR和TPR证实Mn、Ni共存于ABO_3的B位,它们之间存在相互作用。CO和CH_3OH微反考察表明本体系的催化活性与晶系及结晶态密切相关,晶体对称性高,反应活性低。

The correlation of the composition. structure. IR. TPR and catalytic activityfor CO and CH_3OH oxidation on LaMn_(1-x)Ni_xO_3 (0.0≤x≤1.0) has been studied. Thesingle crystalline phase was perovskite in the range of 0. 0≤x≤1.0; samples for0.0≤x≤0. 4 and x=1. 0 were rhombohedral, and cubic with 0. 5≤x≤0.8, and thesamples with x=0.4 and 0.8 were close to the transitional region of rhombohedralto cubic or cubic to rhombohedral. IR and TPR studies proved that there was interac-tion between Mn and Ni in the B site of ABO_3.The catalytic activity of the oxideswas related to the symmetry of the crystal, the higher the symmetry, the lower theactivity.