Partial oxidation of methane over Fe/ZSM-5 with hydrogen peroxide generated in situ over Pd/C in the presence of halide ions

Abstract

The effect of halide ion on the catalytic activity for the aqueous-phase partial oxidation of methane with H2O2 generated in situ over Pd/C was examined. Various halide ions, including F-, Cl-, Br-, and I- were compared. Among them, Br- and I- are effective for the synthesis of H2O2 from H2 and O2, resulting in the synthesis of methane oxygenates from methane over Fe/ZSM-5. They show different product yields as a function of their concentrations. The highest total product yields were obtained with [KBr] = 5 mM and [KI] = 0.05 mM, respectively. Compared with Br-, the highest product yield was obtained with a much lower concentration of I-, guaranteeing that no detectable leaching of metal from Fe/ZSM-5 and Pd/C was found. The total productivity was 4.64 mmol/gcat./h over Fe/ZSM-5 at 50 ℃ with H2O2 generated in situ over Pd/C from H2 and O2 in the presence of 0.05 mM of KI.