Karel Frolich

Evidence of heterogeneous dual cation sites in zeolites by combined IR and DFT investigation

Abstract Interaction of the CO molecule with CuX-FER zeolites (X is an alkali-metal or proton as a co-cation) was investigated by IR spectroscopy and DFT calculations. An absorption band at 2138 cm −1 observed in IR spectra of CO on CuK- and CuCs-FER zeolites was assigned to a new type of CO adsorption complex on heterogeneous dual cation sites. CO molecule interacts simultaneously with Cu + and alkali metal cations (via C- and O-end, respectively) in this type of complex. Interaction of CO with the secondary (alkali metal) cation led to a slight destabilization of the carbonyl complex.

Vibrational dynamics of small molecules adsorbed on cation sites in zeolite channel systems: IR and DFT investigation

Abstract The interaction of CO and acetonitrile with extra-framework metal-cation sites in zeolites was investigated at the periodic DFT level and using IR spectroscopy. The stability and IR spectra of adsorption complexes formed in M + -zeolites can be understood in detail only when both, (i) the interaction of the adsorbed molecule with the metal cation and (ii) the interaction of the opposite end of the molecule (the hydrocarbon part of acetonitrile or the oxygen atom of CO) with the zeolite are considered. These effects, which can be classified as the effect from the bottom and the effect from the top, respectively, are critically analyzed and discussed.