Plasma-catalytic biogas reforming for hydrogen production over K-promoted Ni/Al₂O₃ catalysts: Effect of K-loading

Biogas reforming for hydrogen production was achieved in a tabular dielectric barrier discharge (DBD) system using K-promoted Ni/Al₂O₃ catalysts with varying potassium loadings. The Ni–K/Al₂O₃ catalyst with 2 wt% K loading showed the best reforming performance with a CH₄ conversion of 32% and a CO₂ conversion of 23%, resulting in the highest energy efficiency of 0.67 mmol kJ⁻¹ among the studied catalysts. In comparison to the unpromoted Ni/Al₂O₃ catalyst, the presence of 2 wt% potassium loading enhanced H₂ production while suppressing CO formation, increasing the relative amount of H₂ in the syngas. Furthermore, the Ni–K/Al₂O₃ catalyst (2 wt% K) exhibited the most pronounced plasma-catalytic synergy. The results of thermal gravimetry analysis (TGA) revealed that increasing potassium loading in the catalysts increased carbon production by generating more inactive and less active carbonaceous species (C_γ and C_β) on the catalyst surfaces. This study demonstrates that by tuning the potassium loading of Ni/Al₂O₃ based catalysts, the performance of plasma-catalytic biogas reforming at low temperatures can be enhanced.