Synthesis of Na2WO4-MnxOy supported on SiO2 or La2O3 as fiber catalysts by electrospinning for oxidative coupling of methane: Synthesis of Na2WO4-MnxOy supported on SiO2 or La2O3 as fiber catalysts

Abstract

The oxidative coupling of methane (OCM) is an attractive route to convert natural gas directly into value-added chemical products (C2+). This work comparatively investigated SiO2- or La2O3-supported Na2WO4-MnxOy (denoted as NWM) catalysts in powder and fiber forms. The powder catalysts were prepared using a co-impregnation method and the fiber catalysts were prepared successfully using an electrospinning technique. The NWM/La2O3 fiber catalysts were activated at low temperature (500 °C) and had a 4.7% C2+ yield, with the maximum C2+ yield of 9.6% at 650 °C, while the NWM/SiO2 fiber catalyst was activated at 650 °C and had a maximum C2+ yield of 20.4% at 700 °C. The XPS results in the O 1s region indicated that NWM/La2O3 had a lower binding energy than NWM/SiO2, suggesting that the lattice oxygen species is easily released from the catalyst surface and creates vacancy sites that enhance performance. The stability test of the catalysts indicated that the La2O3-containing catalysts had excellent activity and high thermal stability, while the SiO2-containing catalysts had a higher C2+ yield when the prepared catalysts were compared at 700 °C. Considering the same component catalysts, the fiber catalysts achieved higher performance because their heat and mass transfer properties were enhanced. © 2021 The Author(s)