Nonoxidative Coupling of Methane over Ceria-Supported Single-Atom Pt Catalysts in DBD Plasma

Plasma-catalytic direct nonoxidative coupling of methane (NCM) into C-2 hydrocarbons was investigated over ceria-supported atomically dispersed Pt (Pt/CeO2-SAC) and nanoparticle Pt (Pt/CeO2-NP) catalysts in dielectric barrier discharge (DBD) plasma. Nonthermal plasma facilitated C-H bond dissociation in CH4 at low temperatures (<150 degrees C) and atmospheric pressure. The presence of Pt/CeO2 catalysts in plasma further enhanced CH4 conversion and C-2 hydrocarbon selectivity by enabling the conversion of vibrationally excited methane species with high internal energy on active Pt sites. Noticeably, the Pt/CeO2-SAC catalyst displayed a more remarkable performance, with a CH4 conversion of 39% and a C-2 selectivity of 54% at 54 W. The enhanced CH4 conversion was attributed to abundant coordinatively unsaturated Pt sites in Pt/CeO2-SAC, which were more active for C-H bond scission. Meanwhile, isolated Pt atoms in Pt/CeO2-SAC promoted C-2 hydrocarbon formation by hindering the unselective formation of coke from deep dehydrogenation of CHx center dot intermediates and higher hydrocarbons from oligomerization reactions.

Automated summary

The plasma-catalytic direct nonoxidative coupling of methane into C-2 hydrocarbons was studied using Pt/CeO2-SAC and Pt/CeO2-NP catalysts. Pt/CeO2-SAC catalyst showed higher catalytic activity and selectivity under low temperature and atmospheric pressure. The enhanced CH4 conversion was attributed to abundant active sites in Pt/CeO2-SAC.