Bulánek Roman, Drobná Helena, Nachtigall Petr, Rubes Miroslav, Bludský Ota
Department of Physical Chemistry, University of Pardubice, Nám. Cs. Legií 565, 53010 Pardubice, Czech Republic.
Phys Chem Chem Phys. 2006 Dec 21;8(47):5535-42. doi: 10.1039/b613805e. Epub 2006 Nov 7.
The preferred Cu(+) sites and formation of mono-, di-, and tricarbonyl complexes in the Cu-FER were investigated at the periodic density functional theory level and by means of FTIR spectroscopy. The site-specificity of adsorption enthalpies of CO on Cu-FER and of vibrational frequencies of polycarbonyl complexes were investigated for various Cu(+) sites in Cu-FER. Large changes in the Cu(+) interaction with the zeolite framework were observed upon the formation of carbonyl complexes. The dicarbonyl complexes formed on Cu(+) in the main channel or on the intersection of the main and perpendicular channels are stable and both, adsorption enthalpies and CO stretching frequencies are not site-specific. The fraction of Cu(+) ions in the FER cage, that cannot form dicarbonyl can be determined from IR spectra (about 7% for the Cu-FER with Si/Al = 27.5 investigated here). The tricarbonyl complexes can be formed at the Cu(+) ions located at the 8-member ring window at the intersection of main and perpendicular channel. The stability of tricarbonyl complexes is very low (DeltaH degrees (0 K)>or=-4 kJ mol(-1)).
在周期性密度泛函理论水平上并借助傅里叶变换红外光谱法，研究了Cu-FER中优先的Cu(+)位点以及单羰基、二羰基和三羰基配合物的形成。针对Cu-FER中各种Cu(+)位点，研究了CO在Cu-FER上的吸附焓以及多羰基配合物振动频率的位点特异性。在形成羰基配合物时，观察到Cu(+)与沸石骨架的相互作用发生了很大变化。在主通道中的Cu(+)上或主通道与垂直通道的交叉处形成的二羰基配合物是稳定的，吸附焓和CO伸缩频率都不具有位点特异性。FER笼中不能形成二羰基的Cu(+)离子分数可由红外光谱确定（此处研究的Si/Al = 27.5的Cu-FER约为7%）。三羰基配合物可在主通道与垂直通道交叉处的8元环窗口处的Cu(+)离子上形成。三羰基配合物的稳定性非常低（ΔH°(0 K)≥ -4 kJ mol(-1)）。
