Plasma‐catalytic one‐step steam reforming of methane to methanol: Revealing the catalytic cycle on Cu/mordenite

Direct CH 4 to CH 3 OH conversion is a long‐standing grand challenge in catalysis. We present one‐step steam reforming of methane to methanol (OSRMtM) by combining an atmospheric pressure CH 4 /H 2 O/Ar plasma with a Cu/Mordenite (Cu/MOR) catalyst at 170°C, achieving 77% CH 3 OH selectivity with 3.0% CH 4 conversion. Catalyst characterization and plasma diagnostics, as well as D 2 O and H 2 18 O‐labeled isotope tracer experiments reveal that the excellent reaction performance is attributed to Cu‐O active sites confined by MOR zeolite. During plasma‐catalytic OSRMtM, both CH 4 and H 2 O are activated in the plasma and dissociated to produce radicals (CH 3 , OH, and H). These radicals drive the redox process between Cu 2+ and Cu + , playing an important role in plasma‐catalytic OSRMtM. Although a gradual reduction of Cu 2+ to Cu + leads to slow deactivation, the catalytic performance can be completely recovered through simple calcination, which enables a continuous plasma‐catalytic OSRMtM process using a fluidized‐bed reactor.