助剂作用下金属催化剂M(M=Ru, Rh, Pd)对CO化学吸附的理论研究

用Gaussian98程序、HF方法和LANL2DZ基组，以MCOM1^n (M=Ru,Rh,Pd；M1^n =Na^ ,Mg^2 ,K^ ）为模型，探讨在主族金属阳离子助剂M1^n 作用下，过渡金属催化剂M化学吸附CO后对C-O锓的影响及其机理，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M1^n 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M1^n 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，得电子能力强的主族金属阳离子助剂有更强的更强的助催化作用。

Theoretical Studies of the Chemisorption of CO on Metal Catalysts Under the effects of Promoters

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.