Oxygen-rich ultramicroporous activated carbon for boosting H₂ production via toluene steam reforming: Effect of H₂O₂-modification and Ni/Co loading

The development of sustainable materials to produce a highly stable and efficient tar removal catalyst is important for biomass gasification technology. In this study, the effect of support modification using hydrogen peroxide (H₂O₂) and Ni and/or Co loadings on catalytic performance over palm kernel shell-based activated carbon (AC) supported catalysts for hydrogen (H₂) production via steam reforming of toluene as biomass tar model compound have been investigated. The H₂O₂-modified AC (ACP) registers enhanced surface oxygenated functional groups and ultramicroporosity leading to highly dispersed active metals sites with uniform distribution and high acidity after Ni[sbnd]Co impregnation. The highest activity is conferred by 10%Ni-10%Co/ACP at 93.8% and 90.2% of H₂ yield and toluene conversion, respectively, with 325 h of stability. This is attributed to high turnover frequency, small crystallite size, weak metal-support interaction (WMSI) and simultaneous Ni[sbnd]Co reducibility. The WMSI leads to carbon nanotube formation with tip-growth mechanism and suppresses catalyst deactivation. The reaction is endothermic and non-spontaneous with an ordered system at transition state. The results imply that the oxygenated functionalized ultramicroporous palm kernel shell-based ACP has a great potential as a high-performance catalyst in steam reforming of tar for H₂ production.