Direct oxidation of methane to methanol on Fe-O modified graphene

作者：Impeng Sarawoot; Khongpracha Pipat; Warakulwit Chompunuch; Jansang Bavornpon; Sirijaraensre Jakkapan; Ehara Masahiro; Limtrakul Jumras^*

来源：RSC Advances, 2014, 4(24): 12572-12578.

DOI：10.1039/c3ra47826b

Introduction of functional groups to graphene can be used for the rational design of catalysts for the oxidation of hydrocarbons to alcohols. We have employed the PBE-D2 level of theory to study the direct oxidation of CH4 to CH3OH on a Fe-O active site generated on graphene by the decomposition of nitrous oxide (N2O) over Fe-embedded graphene. Restricted and unrestricted spin state of systems were also taken into account. The calculations show that FeO/graphene provides excellent reactivity for the oxy-functionalization of methane to methanol. The oxygen-centered radicals (O-center dot) on the catalyst can activate the strong C-H bond of methane leading to its homolytic cleavage. The C-H bond activation requires an energy of 17.5 kcal mol(-1), which is comparable with the barrier on traditional effective catalysts. Comparing the molecular adsorption complex, the formation of the iron coordinated fragments of C-H bond activation on the graphene support is found to be less energetically stable than on the Fe sites in the zeolite support. As a result, the conversion of the grafted species to the methanol product in the second step of the reaction is much more facile than for Fe-exchanged zeolite catalysts. An activation energy of 16.4 kcal mol(-1) is required to yield the methanol product. Fe-O modified graphene materials could be promising catalysts for the partial oxidation of methane with N2O as an oxidant.

• 出版日期2014