Partial oxidation of methane on the SiO2 surface - A quantum chemical study

Ozturk, S
Onal, I
Senkan, S
Reaction pathways for methane partial oxidation (MPO) on silica were theoretically investigated using the semiempirical MOPAC-PM3 molecular orbital method. The surface of SiO2 was modeled by a helical Si6O18H12 molecular cluster that also exhibits a strained siloxane bridge defect. First, a bond energy analysis was performed on the silica cluster with isolated 3- and 4-coordinated Si surface atoms. Calculated bond dissociation energies for Si-H, SiO-H, and SI-OH were comparable to H-CH3, H-OH, and O-O. In the second phase, elementary reactions around the bridge structure were studied. The facile ring-opening reaction with water, which reconstitutes a pair of vicinal hydroxyls, was found both thermodynamically and kinetically favored, in good agreement with the experiment and other theoretical methods. Activation of methane by the lattice bridge oxygen was thermodynamically unfavorable with high activation energy. On the other hand, the computational results also confirmed the important role adsorbed or "activated" oxygen plays in an MPO reaction, and indicated the likely formation of methanol as an intermediate in formaldehyde production.


Direct Methane Oxidation to Methanol by N2O on Fe- and Co-ZSM-5 Clusters with and without Water: A Density Functional Theory Study
Fellah, Mehmet Ferdi; Önal, Işık (2010-02-25)
Density functional theory (DFT) calculations were carried Out ill a Study of oxidation of methane to methanol by N2O on the Fe- and Co-ZSM-5 clusters. The catalytic cycle steps have been Studied oil model Clusters ((SiH3)(4)AlO4M) (where M = Fe, Co). Calculations indicate very low methanol selectivity Without water and increasing rate of methanol formation with water. These results are in qualitative agreement with the experimental literature. The methanol formation step is also found to be the rate-limitin...
Quantum chemical study of the catalytic oxidative coupling of methane
Onal, I; Senkan, S (1997-10-01)
Oxidative coupling of methane reaction pathways on MgO and lithium-modified MgO were theoretically studied using the semiempirical MNDO-PM3 molecular orbital method. The surface of the MgO catalyst was modeled by a Mg9O9 molecular cluster containing structural defects such as edges and corners. Lithium-promoted magnesia was simulated by isomorphic substitution of Mg2+ by Li+; the excess negative charge of the cluster was compensated by a proton connected to a neighboring O2- site. Heterolytic adsorption of ...
Thermal decomposition of polystyrene-b-poly(2-vinylpyridine) coordinated to co nanoparticles
Elmaci, Ayşegül; Hacaloğlu, Jale; Kayran, Ceyhan; Sakellariou, Georgios; Hadjichristidis, Nikos (2009-11-01)
Direct pyrolysis mass spectrometry analyses of polystyrene-block-poly(2-vinylpyridne), PS-b-P2VP, indicated that the thermal degradation of each component occurred independently through the decomposition pathways proposed for the corresponding homopolymers; depolymerization for PS and depolymerization and loss of protonated oligomers for P2VP by a more complex degradation mechanism. On the other hand, upon coordination to cobalt nanoparticles, thermal decomposition of the P2VP blocks was initiated by loss o...
Catalytic conversion of methane to methanol on Cu-SSZ-13 using N2O as oxidant
İpek Torun, Bahar (2016-01-01)
Direct catalytic methanol production from methane is achieved on Cu-SSZ-13 zeolite catalysts using N2O as the oxidant. The methanol production rate on Cu-SSZ-13 (on a per gram basis) was more than twice the rate on Cu-mordenite and more than four times the rate on Cu-ZSM-5.
Epoxidation of Propylene on a [Ag14O9] Cluster Representing Ag2O (001) Surface: A Density Functional Theory Study
Fellah, Mehmet Ferdi; Önal, Işık (2012-01-01)
Density functional theory calculations were employed to study partial oxidation of propylene on a [Ag14O9] cluster representing Ag2O (001) surface for which positive effect for ethylene oxide formation has been reported in our earlier work at the same level of theory (Fellah et al., Catal Lett 141: 762, 2011). Propylene oxide (PO), propanal, acetone and G-allyl radical formation reaction mechanisms were investigated. P-allyl formation path and two propylene adsorption paths resulting in PO formation are com...
Citation Formats
S. Ozturk, I. Onal, and S. Senkan, “Partial oxidation of methane on the SiO2 surface - A quantum chemical study,” INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, pp. 250–258, 2000, Accessed: 00, 2020. [Online]. Available: