(114g) Pulsed Plasma Catalyst Design for Dry Reforming of Methane

This study presents a novel pulsed plasma catalytic discharge reactor (PPC) for the dry reforming of methane (DRM) (CH₄ + CO₂ → 2H₂ + 2CO), combining nanosecond pulsed DC plasma with a monolithic catalyst in direct plasma contact. A custom-built solid-state HV pulse generator allows full control over pulse rise time (2–20 ns), duration (0.1–20 μs), shape, and frequency (100–200,000 Hz), enabling energy-efficient operation at atmospheric pressure and <50°C. Reaction kinetics were monitored in situ using a quadrupole mass spectrometer and optical emission spectroscopy. More than 100 mixed metal oxide catalysts supported on high surface area γ-alumina were synthesized and tested. The Cu/Ni catalyst exhibited the best performance, with CH₄ conversion up to 75%, CO₂ conversion of 65%, and H₂ and CO yields exceeding 60% at a 24-second residence time and 15 W input power. The catalyst alone or plasma alone showed <1% conversion, confirming a synergistic plasma-catalyst interaction. The CO/H₂ product ratio was tunable via the CO₂:CH₄ feed ratio, with stoichiometric feeds yielding near 1:1 ratios and higher CO₂ feeds reducing H₂ yield. Emission spectra suggest CO₂ is chemisorbed and reacts with CH₄-derived radicals and atomic H to form CO and H₂. Energy efficiency reached 20–60% under steady-state operation, surpassing typical thermal or plasma-only DRM systems. The research was focused on catalyst surface chemistry, plasma discharge optimization, and reaction mechanism elucidation using spectroscopic and kinetic tools. This work advances PPC-DRM as a scalable, low-temperature route for syngas production from methane and CO₂.