TY - JOUR
T1 - Theoretical studies of the coordination and stability of divalent cations in ZSM-5
AU - Rice, Mark J.
AU - Chakraborty, Arup K.
AU - Bell, Alexis T.
PY - 2000/11/2
Y1 - 2000/11/2
N2 - The coordination of divalent metal cations to ZSM-5 has been investigated using gradient-corrected density functional theory (DFT). Coordination at both isolated charge-exchange sites and pairs of charge-exchange sites was considered for Co2+, Cu2+, Fe2+, Ni2+, Pd2+, Pt2+, Ru2+, Rh2+, and Zn2+. Thermodynamic calculations of the stability of M2+ to reduction to M0 and demetalation to form MOx particles were also carried out. The results indicate that Cu2+, Co2+, Fe2+, and Ni2+ are coordinated preferentially to five-membered rings containing two Al atoms, which are located on the walls of the sinusoidal channels, whereas Pd2+, Pt2+, Ru2+, Rh2+, and Zn2+ are coordinated preferentially to six-membered rings located on the walls of the sinusoidal channels. Examination of the stability of dimer cations of the form [M-O-M]2+ shows that such structures are not generally stable to hydrolysis, with the possible exception of [Cu-O-Cu]2+. The findings of these calculations are in good general agreement with experimental results.
AB - The coordination of divalent metal cations to ZSM-5 has been investigated using gradient-corrected density functional theory (DFT). Coordination at both isolated charge-exchange sites and pairs of charge-exchange sites was considered for Co2+, Cu2+, Fe2+, Ni2+, Pd2+, Pt2+, Ru2+, Rh2+, and Zn2+. Thermodynamic calculations of the stability of M2+ to reduction to M0 and demetalation to form MOx particles were also carried out. The results indicate that Cu2+, Co2+, Fe2+, and Ni2+ are coordinated preferentially to five-membered rings containing two Al atoms, which are located on the walls of the sinusoidal channels, whereas Pd2+, Pt2+, Ru2+, Rh2+, and Zn2+ are coordinated preferentially to six-membered rings located on the walls of the sinusoidal channels. Examination of the stability of dimer cations of the form [M-O-M]2+ shows that such structures are not generally stable to hydrolysis, with the possible exception of [Cu-O-Cu]2+. The findings of these calculations are in good general agreement with experimental results.
UR - http://www.scopus.com/inward/record.url?scp=0034322504&partnerID=8YFLogxK
U2 - 10.1021/jp0009352
DO - 10.1021/jp0009352
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AN - SCOPUS:0034322504
SN - 1089-5647
VL - 104
SP - 9987
EP - 9992
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 43
ER -