Abstract
Microwave-assisted methane (CH4) conversion offers a transformative pathway for hydrogen and syngas production. This review systematically examines microwave catalysis and microwave plasma technologies across four key routes: methane pyrolysis (MP), dry reforming (DRM), steam reforming (SMR), and partial oxidation (POM). Microwave irradiation reduces activation energy by up to 45% for MP (from 45.5 to 24.8 kJ/mol) and 29% for DRM (from 90.8 to 64.2 kJ/mol for CH4), while enabling 250 °C lower operating temperatures compared to conventional heating. Microwave plasma achieves CH4 conversion >90% at near-ambient bulk temperatures, and variable-frequency microwave enables in-situ catalyst reactivation for stable operation >1300 min. Despite these advantages, most microwave-assisted systems remain at TRL 3–7, with key challenges including non-uniform heating, catalyst deactivation, and scale-up. By critically comparing thermal vs. non-thermal effects and microwave catalysis vs. plasma, this review identifies research priorities: microwave-specific catalyst design, reactor engineering for uniform field distribution, and integration with renewable electricity. This work provides a quantitative foundation for advancing microwave-assisted methane conversion from laboratory discovery toward industrial deployment.