Efficient Synthesis of Monomeric Fe Species in Zeolite ZSM-5 for the Low-Temperature Oxidation of Methane

Abstract

Direct oxidation of methane into value-added C1 oxygenated products, such as methanol, is essential and remains a significant challenge in the field of catalysis. In this work, we have prepared Fe/ZSM-5 materials via three different methods and investigated the influence of various preparation methods on the composition and catalytic performance of Fe/ZSM-5 for the low-temperature oxidation of methane. Through a combination of scanning transmission electron microscopy, ultraviolet-visible diffuse reflectance and 57Fe Mössbauer spectroscopy, we have found that the highest proportion of monomeric Fe species of 71 % could be achieved in the ZSM-5 zeolite by the solid-state ion-exchange method, affording an excellent C1 oxygenates yield of 120 mol/molFe with a C1 oxygenates selectivity of 96 % at 50 °C for 30 min in the aqueous solution of H2O2.