H2-reduced phosphomolybdate promotes room-temperature aerobic oxidation of methane to methanol

Abstract

The selective partial oxidation of methane to methanol using molecular oxygen (O2) represents a long-standing challenge, inspiring extensive study for many decades. However, considerable challenges still prevent low-temperature methane activation via the aerobic route. Here we report a precipitated Pd-containing phosphomolybdate, which, after activation by molecular hydrogen (H2), converts methane and O2 almost exclusively to methanol at room temperature. The highest activity reaches 67.4 μmol gcat−1 h−1. Pd enables rapid H2 activation and H spillover to phosphomolybdate for Mo reduction, while facile O2 activation and subsequent methane activation occur on the reduced phosphomolybdate sites. Continuous production of methanol from methane was also achieved by concurrently introducing H2, O2 and methane into the system, where H2 assists in maintaining a moderately reduced state of phosphomolybdate. This work reveals the underexplored potential of such a Mo-based catalyst for aerobic methane oxidation and highlights the importance of regulating the chemical valence state to construct methane active sites. The partial oxidation of methane to methanol is a very attractive yet challenging process. Now, a H2-reduced Pd-containing phosphomolybdate catalyst is reported to convert methane and O2 to methanol with nearly 100% selectivity at room temperature.