Catalytic behaviour of CuOx and VOx on Ti3SiC2 support for direct oxidation of methane

Abstract

Herein we show that the Ti₃SiC₂ MAX phase can be used as a support for deposition of different amounts of metal oxides (MO_x, M = Cu or V) (5, 10 and 20 wt%) for the direct oxidation of methane to formaldehyde using molecular oxygen, at relatively low temperatures and atmospheric pressure. The oxides were deposited using a hydrothermal method at 180 °C without affecting the bulk MAX phase structure. However, during the hydrothermal treatment (HT) a thin oxide layer - found to play an important role in the reaction's selectivity– was evidenced by X-ray photoelectron spectroscopy. We thus conclude that the MO_x species are responsible for the CH₄ activation, while the Ti₃SiC₂ surface is responsible for the high selectivity to formaldehyde indicating that, Ti₃SiC₂ has great potential for designing innovative catalysts for direct oxidation of methane using molecular oxygen and at atmospheric pressure.