Growth of carbon nanofibers synthesized from CO₂ hydrogenation on a K/Ni/Al₂O₃ catalyst

We used a commercially available Ni/Al₂O₃ sample containing K additive to enable carbon deposition from CO₂ exposure by means of catalytic hydrogenation. Our experimental results suggest that K additives induce the formation of carbon nanofibers (CNFs) or carbon deposition on Ni/Al₂O₃ during the CO₂ hydrogenation reaction. We propose that the rate of carbon deposition depends on the reaction temperature, on H₂ and CO₂ partial pressures, and on the reactant residence time. Furthermore, we suggest that the creation of a K-relevant active phase may be involved in the carbon deposition process. Our results also indicate that the degree of CNF graphitization can change with reaction time.