On the possible removal of nitrogen monoxide and carbon monoxide on copper ion-exchanged montmorillonite: A DFT study

摘要

DFT calculations have been carried out in order to study the possibilities of Cu ion-exchanged Montmorillonite to act as matrix in two important chemical processes: the possible N-O bond breaking in NO molecule and the CO, formation as the result of CO oxidation. The adsorptions of NO, C-O and O-2 on Cu+1-Montmorillonite (Cu+1-MMT were modeled using the cluster methodology at the BLYP level of theory. The binding energies related with the adsorption processes of CO, NO and O-2 were of -30, -26 and -13 kcal/mol, respectively, these results indicate that the corresponding processes are favored. Moreover, it was found that the oxidation of CO throughout a Langrnuir-Rideal type unimolecular mechanism is a highly favored process because the change of the electronic energy was of -166, 26 kcal mol(-1). In relation to NO molecule, a coadsorption of a second molecule was attempted; the negative value of -19.56 kcal mol(-1) for the change in the electronic energy suggests that a second NO molecule can also be adsorbed and probably a dimer of NO could be formed. According to the results we think that Cu ion-exchanged Montmorillonite could be an interesting catalytic system to be tested in environmental applications. (c) 2008 Wiley Periodicals, Inc.