Affiliations: Laboratorio de Química Computacional, Centro de Química, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela | [x] Centro de Química, Instituto Venezolano de Investigaciones Científicas, IVIC, Caracas, Venezuela | [y] Departamento de Química, Instituto Universitario de Tecnología FRP, Caracas, Venezuela
Correspondence:
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Corresponding author: Anibal Sierraalta, Laboratorio de Química Computacional, Centro de Química, Instituto Venezolano de Investigaciones Científicas, Apartado, Caracas, Venezuela. E-mail: [email protected].
Abstract: In this study, we carried out two-layer ONIOM(DFT:MM) calculations to determine the adsorption enthalpies and vibrational frequencies of NO and CO molecules, on palladium exchanged zeolite (Pd/ZSM-5) catalyst. The results reveal that the local Al distribution near to Pd+2 influence the stretching frequencies as well as the adsorption enthalpies. The nine possible Al distributions studied can be gathered in two groups. One responsible for high CO and NO frequencies (εCO = 2146 cm-1 and εNO = 1880 cm-1) and the other one responsible for the low frequencies (εCO = 2127 cm-1 and εNO = 1840 cm-1). In general, the adsorption enthalpy of the CO is similar to the NO therefore; there is not a preferential adsorption of CO over the NO molecule.
