Interaction of CO Molecule with Au/MOR Catalyst: ONIOM-PM6 Study, Active Sites, Thermodynamic and Vibrational Frequencies

ONIOM calculations have been carried out to determine geometries, adsorption energies, and vibrational frequencies of CO on a model for Au-exchanged mordenite catalysts, Au/MOR. The CO-calculated vibrational frequencies (upsilon(CO)) are in good agreement with the reported experimental values. We proposed to interpret the frequency results. CH3COCH3 and CH3SH adsorption enthalpy calculations on Au/MOR model show that the Au/MOR catalyst behaves like a soft acid according to Pearson's rule. A higher structural deformation degree of the mordenite was found in the calculations with PM6 than with universal force field approach approach. A new pseudopotential (ACEP-121) was developed to improve the Au-Au distance, and Au ionization potential.