A. Kamper et al., A molecular mechanics study of the adsorption of ethane and propane on V2O5(001) surfaces with oxygen vacancies, TOP CATAL, 11(1-4), 2000, pp. 77-84
Adsorption geometries and energies of ethane and propane physisorbed on the
(001) surface of vanadium pentoxide with oxygen vacancies were determined
by a molecular mechanics simulation. Three types of oxygen vacancies, built
up by removal of vanadyl oxygen, two-fold and three-fold coordinated oxyge
n, respectively, have been modeled as defects. The energetically most favor
able adsorption site is on top of a vacancy of two-fold coordinated oxygen
for ethane and propane, respectively. The next favorable site for both alka
nes is on top of a vacancy of vanadyl oxygen. Due to the generation of a "v
an der Waals cage" which traps the hydrocarbon the adsorption on the defect
site is favored in comparison with the ideal surface for these two defect
types. A vacancy of three-fold coordinated oxygen does not lead to an enhan
cement of adsorption and pushes the reactant towards the unperturbed surfac
e areas due to the fact, that no energy minimum can be obtained in the vici
nity of the defect.