Cobalt decorated egg-shell-type activated carbon pellets: Catalytic application in hydrogen release from boron based solid fuel

Abstract

Hydrogen became zero-carbon fuel used in fuel-cell or internal combustion engines, regard- ing energy sector green-hydrogen also has become an energy carrier in commercial appli- cations. For supporting decarbonization strategies based on hydrogen, boron-fuels are good options to safely store for mobile technologies. Ammonia borane (NH3BH3) is the one of the boron based fuels that stored 19.6 wt.% H2 in its structure chemically. Cobalt (Co) decorated egg-shell-type activated carbon pellets were synthesized for catalytic application of hydrogen release from NH3BH3. Two different sized pellet type activated carbon was decorated with co- balt by combined procedure as modified vacuum-impregnation method with heat fixation and reduction. The obtained catalysts were characterized by applying optical microscope (OM), scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDS), transmis- sion electron microscopy (TEM), nitrogen sorption based surface analyses (BET). Activated carbon provides porous structure for effectively dispersion Co particles while the outer shell shows the catalytic activity for hydrogen generation. Structural characterization results and preliminary activity tests confirmed that fabricated Co@ACPB exhibited better performance compared with Co@ACPS catalysts thanks to thinner shell thickness and higher BET surface area/pore volume properties. The results of the kinetic study showed the core-shell type Co based catalyst catalyzed the reaction and follows the zero-order reaction kinetic model with 41.78 kJmol-1. Activated carbon pellets provide well dispersion and stability of active Co sites, easy separation of used catalysts after the reaction and enable practical regeneration of cata- lytic materials.