Oxidative Dehydrogenation Of Methane Research Articles

Oxidative Dehydrogenation of Methane When Using TiO2- or WO3-Doped Sm2O3 in the Presence of Active Oxygen Excited with UV-LED

There are active oxygen species that contribute to oxidative coupling or the partial oxidation during the oxidative dehydrogenation of methane when using solid oxide catalysts, and those species have not been definitively identified. In the present study, we clarify which of the active oxygen species affect the oxidative dehydrogenation of methane by employing photo-catalysts such as TiO2 or WO3, which generate active oxygen from UV-LED irradiation conditions under an oxygen flow. These photo-catalysts were studied in combination with Sm2O3, which is a methane oxidation coupling catalyst. For this purpose, we constructed a reaction system that could directly irradiate UV-LED to a solid catalyst via a normal fixed-bed continuous-flow reactor operated at atmospheric pressure. Binary catalysts prepared from TiO2 or WO3 were either supported on or kneaded with Sm2O3 in the present study. UV-LED irradiation clearly improved the partial oxidation from methane to CO and/or slightly improved the oxidative coupling route from methane to ethylene when binary catalysts consisting of Sm2O3 and TiO2 are used, while negligible UV-LED effects were detected when using Sm2O3 and WO3. These results indicate that with UV-LED irradiation the active oxygen of O2− from TiO2 certainly contributes to the activation of methane during the oxidative dehydrogenation of methane when using Sm2O3, while the active oxygen of H2O2 from WO3 under the same conditions afforded only negligible effects on the activation of methane.

Oxidative Dehydrogenation of Methane by Isolated Vanadium Oxide Clusters Supported on Au (111) and Ag (111) Surfaces

We use density functional theory, with the GGA-PBE functional, to investigate the ability of vanadium oxide clusters, supported on Ag or Au, to break the C–H bond in methane. We perform a thermodynamic analysis to show that the VO4 cluster is the most likely oxidant and then proceed to calculate the energy of the dissociative adsorption of methane and its activation energy. We explain some peculiar features of the reaction path and propose that they are general for alkane activation on oxides.

クロムで修飾したFSM-16によるメタン、エタン、プロパン、イソブタンの酸化脱水素反応

クロムで修飾したFSM-16によるメタン、エタン、プロパン、イソブタンの酸化脱水素反応

Cation effects in the oxidative dehydrogenation of methane on sulphates

The oxidative coupling of methane has been studied on Mg, Ca, Sr and Ba sulphate. The conversions and selectivities are found to be dependent on the nature of the cation and to be approximately correlated with their electronegativities, thus implying that the C-H bond scission in CH4, at least with these catalysts, is heterolytic, is rate determining, and further, that the formation of C2+ hydrocarbons is dependent, among other factors, on the concentration of methyl radicals.

ChemInform Abstract: Supported Lithium Tetraborate as a Catalyst for the Continuous Oxidative Dehydrogenation of Methane.

Recent work from this laboratory has shown that quite extensive noncatalyzed gas-phase reactions take place between dilute methane and oxygen mixtures in the region 600-720{degree}C. The main products were found to be mostly CO and CO{sub 2}, together with some C{sub 2}H{sub 4} and C{sub 2}H{sub 6}. Since then, other workers have published detailed studies on the gas-phase oxidation of methane, in general agreement with this data. Furthermore, this work showed that one of the catalysts previously studied for this reaction, namely Li{sub 2}CO{sub 3} on MgO, while doubling the amount of C{sub 2}'s formed homogeneously, also oxidized almost all of the homogeneously formed CO to CO{sub 2}. Hence, if a catalyst that would not oxidize CO to CO{sub 2}, while still forming C{sub 2}H{sub 4} and C{sub 2}H{sub 6}, could be found, it would be of considerable importance. The authors have found that lithium tetraborate (LTB) supported on MgO does not oxidize CO, while showing activity for the formation of C{sub 2}'s. To investigate the effect of the support, catalysts have also been prepared using silica and alumina. Results are discussed.

Supported lithium tetraborate as a catalyst for the continuous oxidative dehydrogenation of methane

Recent work from this laboratory has shown that quite extensive noncatalyzed gas-phase reactions take place between dilute methane and oxygen mixtures in the region 600-720{degree}C. The main products were found to be mostly CO and CO{sub 2}, together with some C{sub 2}H{sub 4} and C{sub 2}H{sub 6}. Since then, other workers have published detailed studies on the gas-phase oxidation of methane, in general agreement with this data. Furthermore, this work showed that one of the catalysts previously studied for this reaction, namely Li{sub 2}CO{sub 3} on MgO, while doubling the amount of C{sub 2}'s formed homogeneously, also oxidized almost all of the homogeneously formed CO to CO{sub 2}. Hence, if a catalyst that would not oxidize CO to CO{sub 2}, while still forming C{sub 2}H{sub 4} and C{sub 2}H{sub 6}, could be found, it would be of considerable importance. The authors have found that lithium tetraborate (LTB) supported on MgO does not oxidize CO, while showing activity for the formation of C{sub 2}'s. To investigate the effect of the support, catalysts have also been prepared using silica and alumina. Results are discussed.