Screening of MgO- and CeO₂-Based Catalysts for Carbon Dioxide Oxidative Coupling of Methane to C₂₊ Hydrocarbons

The catalyst screening tests for CO₂ oxidative coupling of methane (CO₂-OCM) were studied over ternary and binary metal oxide catalysts. The catalysts were prepared by doping MgO- and CeO₂-based solids with oxides from alkali (Li₂O), alkaline earth (CaO), and transition metal groups (WO₃ or MnO). The high reducibility of the CeO₂ catalyst, an important factor in the CO₂-OCM catalyst activity, could be enhanced by the presence of manganese oxide species. These species increased oxygen mobility and oxygen vacancies in the CeO₂ catalyst. The performance of 5%/MnO/15%CaO/CeO₂ catalyst was the most potential among the CeO₂-based catalysts. The 2%Li₂O/MgO catalyst showed the most promising C₂₊ hydrocarbons selectivity and yield at 98 and 5.7%, respectively. Carbon in CO₂ was only converted into CO. Carbon and/or hydrogen in methane were only converted into ethane, ethylene acetylene, and CO and/or hydrogen and water, respectively.