Intensification of plasma-catalytic processes via additive manufacturing. Application to non-oxidative methane coupling to ethylene

Electrification of chemical processes involving stable molecules can be intensified by additive manufacturing of modular catalytic reactors. We perform single pass conversion of methane (CH4) into ethylene (C2H4) via a nanosecond-pulsed discharge (NPD) plasma coupled with tailor-made 3D-printed catalytic periodic open cell structures (POCS) without external heat or H2. The plasma discharge effectively activates CH4 yielding an acetylene-rich (C2H2) mixture that is hydrogenated in post-plasma with Pd/Al2O3 catalyst deposited on three different copper (Cu) POCS. The POCS assembly, embedded in the ground electrode, enables the plasma discharge, while it promotes the hydrogenation reaction via enhanced heat recovery from the plasma zone. The temperature profile inside the catalytic bed flattens due to the high axial thermal conductivity of the (Cu) POCS. 45 % CH4 conversion is attained in the plasma, with overall 28 % C2H4 yield resulting from post-plasma hydrogenation. All tested POCS drive C2H2 conversion above 93 % via enhanced convective and conductive heat transfer with the plasma zone.