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

Abstract

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 (Cγ and Cβ) 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.