Nitrogen Fixation Through Al ₂ O ₃ –Based Catalysts Embedded in a Microwave Plasma Post–Discharge

ABSTRACT The conventional Haber–Bosch process for nitrogen fixation is energy‐intensive and associated with high greenhouse gas emissions. Plasma‐assisted catalysis represents an alternative approach for nitrogen oxidation under milder conditions. In this study, catalyst‐assisted microwave plasma was investigated using alumina‐based catalysts and alumina‐supported metal oxides (Mo, W, Co, and Ni). Microwave plasma alone predominantly produced NO, whereas the presence of catalysts promoted additional NO 2 formation, indicating the importance of plasma–catalyst interactions. Catalytic performance depended strongly on the physicochemical properties of alumina, with δ‐Al 2 O 3 exhibiting the highest activity. Mo‐ and W‐loaded catalysts further enhanced NO x formation, while Ni and Co showed weaker effects. An overall increase of up to ~30% in NO x production was achieved compared to plasma alone.