METHANE LIQUEFACTION: Selective Conversion of Methane to Cyclohexane via Efficient Surface-Hydrogen-Transfer Catalyzed by GaN-Supported Platinum Clusters

Non-oxidative liquefaction of methane at room temperature and ambient pressure has long been a scientific “holy grail” of chemical research. In this report, we exploit an unprecedented catalytic transformation of methane exclusively to cyclohexane through effective surface-hydrogen-transfer (SHT) at the heterojunctions boundary consisting of electron-rich platinum cluster (Pt) loaded on methane-activating gallium nitride (GaN) host. The experimental analysis demonstrates that interface-induced overall reaction starts with methane aromatization to benzene initiated by the Ga-N pairs, followed by hydrogenation of benzene to cyclohexane via hydrogen transfer. The in-situ activated hydrogen at electron-rich metal Pt cluster plays a key role for the hydrogenation and enables an outstanding selectivity (as high as 89 %) towards cyclohexane, which is well-delivered even after 5 recycling runs.

Photoelectrochemical Conversion of Methane into Value-Added Products

Methane has been reported to be directly converted into value-added products through various methods. Among them, photoelectrochemical (PEC) methane conversion is considered an eco-friendly method because it utilizes solar light and is able to control the selectivity to different products by means of application of an external bias. Recently, some PEC methane conversion systems have been reported, but their performance efficiencies are relatively lower than those of other existing thermal, photocatalytic, and electrochemical systems. The detailed mechanism of methane activation is not clear at this stage. In this review, various catalytic materials and their roles in the reaction pathways are summarized and discussed. Furthermore, promising semiconductor materials, co-catalysts, and oxidants have also been proposed. Finally, direct and indirect pathways in the design of the PEC methane conversion system have been discussed.