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.