Synthesis of Ni-CeO2 catalyst for the partial oxidation of methane using RF thermal plasma

Abstract

Ni-CeO2 catalysts with a nickel content of 50 mol% were prepared using RF thermal plasma, and their catalytic activities for methane partial oxidation were characterized. For the synthesis of Ni-CeO2 catalysts, a precursor containing Ni (∼5-μm diameter) and CeO2 (∼200-nm diameter) powders were heated simultaneously using an RF plasma at a power level of ∼52 kVA and a powder feeding rate of ∼120 g/h. From the X-ray diffraction data and transmission electron microscopy images, the precursor formed into high crystalline CeO2 supports with nanosized Ni particles (<–50-nm diameter) on their surfaces. The catalytic performance was evaluated under atmospheric pressure at > 500 °C and a CH4:O2 molar ratio of 2:1 with Ar diluent. Although the Ni content was high (∼50 mol%), the experimental results reveal a methane conversion rate of > 70%, selectivities of CO and H2 greater than 90% and slight carbon coking during an on-stream test at 550 °C for 24 h. However, at 750 °C, the on-stream test revealed the formation of filament-like carbons with an increased methane conversion rate over 90%.