摘要
用 Gaussian 98程序、 HF方法和 LANL2 DZ基组 ,以 MCOMn+ 1 ( M=Ru,Rh,Pd;Mn+ 1 =Na+ ,Mg2 + ,K+ )为模型 ,探讨在主族金属阳离子助剂 Mn+ 1 作用下 ,过渡金属催化剂 M化学吸附 CO后对 C— O键的影响及其机理 ,并进一步推测最终对 CO氢化反应产物的影响 .结果表明 ,主族金属阳离子助剂 Mn+ 1 以不同方式与 MCO相作用及选用不同的助剂作用时 ,催化剂具有不同的催化活性和选择性 ,且对 C—O键的削弱程度不同 ,导致生成不同的产物 .当主族金属阳离子助剂 Mn+ 1 与 CO中的 O作用时 ,C— O键被削弱程度比无助剂时大 ,更有利于生成烃类化合物 ;当与过渡金属 M作用时 ,C— O键被削弱程度减小 ,有利于含氧化合物的生成 ;当助剂与 CO以侧基作用时 ,无助催化活性 ;当用不同的主族金属阳离子作助剂时 ,C— O键被削弱程度也不同 。
The calculations have been performed for model systems MCOM\+\{\%n\%+\}\-1(M=Ru, Rh, Pd; M\+\{\%n\%+\}\-1=Na\++, K\++, Mg\+\{2+\}) by Gaussian programs at the HF/LANL2DZ level. The influences of C\_O bond and its mechanism have been studied after the CO adsorbed on the main group metal cation M\+\{\%n\%+\}\-1 promoted transition metal catalysts. And the products of CO hydrogenation on these catalysts have been inferred. The calculations showed that the different interaction positions of the main group metal cation promoter and the various kinds of metal cation promoters both cause the changes of catalyst activity and selectivity. When M\+\{\%n\%+\}\-1 cations affect the CO through the O atom of CO, the C\_O bond is weakened largely and the products of CO hydrogenation over these catalysts will shift to hydrocarbons. When the M\+\{\%n\%+\}\-1 cations affect the CO through the transition metal atom, the C\_O bond is weakened slightly, so it is beneficial to form oxygenates. And there is no activity when M\+\{\%n\%+\}\-1 cations bonded on the side of CO. It can also be concluded that the main group metal cation with stronger ability to accept the electrons may be a better promoter.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
2001年第12期2052-2055,共4页
Chemical Journal of Chinese Universities
基金
辽宁省教育委员会科学基金
吉林大学理论化学计算国家重点实验室资助
