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Mn2O3-Na2WO4 doping of CexZr1-xO2 enables increased activity and selectivity for low temperature oxidative coupling of methane

Weidong Sun,Ya Gao,Guofeng Zhao,Jiaqi Si,Ye Liu,Yong Lu

Ethylene in principle can be obtained via oxidative coupling of methane (OCM), but it is urgently calling for a low-temperature active and selective catalyst. To accomplish this goal, the Ce x Zr 1-x O 2 solid solutions with varied Ce/Zr molar ratio were modified with Mn 2 O 3 -Na 2 WO 4 to fabricate OCM catalysts. The effects of Ce/Zr ratio and Mn 2 O 3 -Na 2 WO 4 doping were investigated on the catalyst reactivity for the OCM, showing that the reaction light-off temperature, activity and selectivity are subject to the Ce/Zr molar ratio and Mn 2 O 3 -Na 2 WO 4 doping. The promising catalyst with Ce/Zr molar ratio of 0.15/0.85 achieves 25% CH 4 conversion with 67% selectivity to C 2 -C 3 at 660 °C and is stable for at least 100 h. The catalysts were systematically studied by CH 4 -TPSR, O 2 -TPO/-TPD, CH 4 -pulse, in-situ FT-IR, EPR and XPS, showing that the Mn 2 O 3 -Na 2 WO 4 doped Ce 0.15 Zr 0.85 O 2 can generate more O 2 – species thereby leading to a markedly improved activity and selectivity at much lowered reaction temperature.