摘要
用漫反射付立叶红外光谱法（ＤＲＩＦＴ）研究了二氧化碳甲烷化催化剂Ｎｉ／Ａｌ２Ｏ３体系的表面物种及催化反应过程．结果表明：二氧化碳难以直接在催化剂表面发生吸附，而是通过与其它反应物的作用，生成含氧酸根类表面吸附物种，并以此为主要中间物进行下一步反应．含氧酸根类物种主要吸附于载体表面．一氧化碳不是反应的主要中间物。
In this paper, a diffuse reflectance infrared cell with heating and temperature controlled parts for in situ mechanistic studies is described, and the surface species and mechanism of the methanation of carbon dioxide over a nickel/alumina catalyst prepared by wet impregnation have been studied by diffuse reflectance infrared Fourier transform spectroscopy. Spectroscopic investigations show that three bonds around 1380, 1590 and 2000 cm -1 emerge after catalytic reaction. Those absorptions are assigned to C-O stretching frequencies of formate and carbon monoxide which are adsorbed on the surface of the catalyst. The absorption around 2300 cm -1 which can be assigned to C-O frequency of surface carbon dioxide has not been found. The results of transient and steady state experiments indicate that methane can not be yielded by the direct hydrogenation of carbon dioxide. The major intermediate is surface formate which has been formed by the reaction between carbon dioxide and another reactant adsorbed on the surface of alumina used as the catalyst support. Carbon monoxide is identified as a by product of carbon dioxide methanation. It is formed from the hydrogenation of the intermediate rather than the reverse process of water gas shift reaction.
出处
《分子催化》
CSCD
1996年第3期201-206,共6页
Journal of Molecular Catalysis(China)
关键词
红外光谱法
二氧化碳
甲烷化
表面物种
催化剂
Diffuse reflectance infrared Fourier transform spectroscopy
Carbon dioxide
Methanation
Nickel/alumina catalyst
Surface species
