Secondary ion mass spectrometry and X-ray photoelectron spectroscopy of Na2MoO4/SiO2 catalysts for methane oxidative coupling

Abstract

A series of Na₂MoO₄/SiO₂ catalysts with various loadings of Na₂MoO₄ have been characterized using secondary ion mass spectrometry (SIMS), X-ray photoelectron spectroscopy (XPS), FTIR and X-ray diffraction (XRD). Their catalytic activity for methane oxidative coupling (MOC) has been tested. The results revealed some type of interaction between Na₂MoO₄ and SiO₂, which leads to a high dispersion of NaMoO₄ at the support surface. The highly dispersed species covering the catalyst surface favour the formation of surface sites of low coordination. The relationship between catalytic performance and the amount of surface sites of low coordination was discussed.