稀土Pr_6O_(11)表面上低碳烃氧化反应的原位FT-IR研究  

SURFACE OXIDATION OF LIGHT HYDROCARBONS ON PRASEODYMIUM OXIDE STUDIED BY IN SITU FT-IR SPECTROSCOPY

作　　者：蒋宗轩[1] 李灿[1] 辛勤[1] 

机构地区：[1]中国科学院大连化学物理研究所催化基础国家重点实验室,大连116023

出　　处：《Chinese Journal of Catalysis》1993年第3期229-233,共5页催化学报（英文）

基　　金：国家自然科学基金(青年基金)

摘　　要：前文报道了CO与Pr_6O_(11)表面反应的结果.已发表的关于烃类与氧化物表面反应的研究,旨在了解烃类的活化和表面氧化机理,而且大部分工作都是在过渡金属氧化物上进行的.近年来的研究表明,稀土氧化物将是有潜力的甲烷氧化偶联制乙烯的催化剂,在消除环境污染的烃类完全氧化催化剂中,稀土氧化物也常被用作助剂或活性组分,但对于稀土氧化物本身的催化表面研究尚不多见.作者曾较系统地研究了CeO_2的表面催化性质,发现表面上存在多种氧物种。Surface oxidation of light hydrocarbons (methane, ethane and ethy-lene) on praseodymium oxide (Pr6O11) has been studied by in situ FT-IR spectroscopy. The oxidation of these hydrocarbons took place facilely on a well-outgassed Pr6O11 at mild temperature even in the absence of gaseous oxygen. Formate species were mainly formed on the surface at temperatures below 573 K for methane and ethane or ethylene. As the temperature was exceeding 573 K, the formate species was oxidized to surface carbonate species which were decomposed into CO2 at further increased temperature. The presence of gaseous oxygen seemed to accelerate the mild oxidation of hydrocarbons on Pr6O11, It is suggested that the active oxygen species responsible for the mild oxidation are surface lattice oxygen which are in coordinatively unsaturated state caused by outgassing at high temperature. The adsorbed oxygen converts most possibly into the coordinativel y unsaturated surface oxygen prior to the lattice oxygen. The complete oxidation of light hydrocarbons on Pr6O11 is commonly via the surface formate and carbonate species.

关 键 词：甲烷 乙烷 乙烯 表面氧化 氧化镨 

分 类 号：O623.11[理学—有机化学]