Fig. 2. Reaction network underlying the liquid phase methane oxidation with H₂O₂ by Fe₂ sites in MIL-53. The formation of the catalytic species 3 – the reaction of the reduced site 1 with H₂O₂ – is detailed in Fig. 3A. Cycle I shows the oxidation of methanol to CO₂. Each colour indicates an oxidation step: light green: CH₄ → CH₃OH, yellow and purple: CH₃OH → CH₂O, light blue: CH₂O → CO, dark blue: CH₂O → HCOOH, brown: CO → CO₂, and orange: HCOOH → CO₂. Cycle II depicts the oxidation of a second H₂O₂ to O₂ and the formation of H₂O. All oxidation reactions occur over the same active site (3).