摘要
采用DV-Xα-SCC方法研究用铑催化剂在有助剂MnO和无助剂两种情况下转化合成气产生的甲酰基中间体,讨论了它在催化剂表面的稳定状态、电子结构及成键性质.结果表明,吸附态甲酰基在催化剂表面形成金属氧卡宾结构,稳定了体系.与无助剂的情况相比,助催剂MnO可使体系更稳定,并使C-O键受到更大程度的削弱,同时它还对中间体的反应行为产生影响.
Formyl intermediate is studied by DV-Xa-SCC method as an active species formed in the process of syngas conversion to ethanol over the Rh/SiO2 and Rh-MnO/SiO2 catalysts. The stable states and the electronic structures as well as the bond properties of formyl on the surface of catalysts studied are discussed. HC = O adsorbed on the catalyst surface is stablized by forming a metal-oxygen carbene structure. This new structure keeps high activity as an intermediate in syngas conversion reactions, with stronger Rh-C bond and weaker C-O bond than its former Rh-CHO structure. Compared with the formyl formed over unpromoted Rh-catalyst, the formyl formed over MnO-promoted Rh-catalyust is more stable, and not only has the C-O bond weakened more markedly but also behaves in a slightly different way in the reaction tendency.
出处
《分子催化》
EI
CAS
CSCD
1993年第2期119-126,共8页
Journal of Molecular Catalysis(China)
关键词
铑
催化剂
甲酰基
乙醇
中间体
Rh catalysts, DV-Xα-SCC method, Formyl, Metal-oxygen-carbene structure.
