Preparation and characterization of Ni/Al2O3 for carbon nanofiber fabrication from CO2 hydrogenation

In this study, Ni/Al2O3 was prepared with an impregnation method for CO2 hydrogenation into carbon nano fibers (CNFs). High purity CNFs were acquired from CO2 hydrogenation at 500 degrees C and 1 atm over Ni/Al2O3 catalyst after a liquid phase extraction process, removing the used catalysts and by-products. The particle properties of as-prepared Ni/Al2O3 have been well characterized for comparison with the commercial ones. The results of XPS spectra and XRPD patterns indicated that the commercial, as-prepared, and used Ni/Al2O3 were multicomponent with various crystal phases. The as-prepared Ni/Al2O3 can be sufficiently exposed in CO2 atmosphere for higher catalytic performances owing to its unique microstructure with higher specific surface area (429.2 m(2)/g). Both EXAFS and XANES spectra have shown that the first shell of Ni atom in commercial, as prepared, and used Ni/Al2O3 were Ni-O with bond distances of 1.61, 1.63, and 1.62 A, respectively. The configuration of fabricated CNFs was characterized by its unique ID/IG (Intensities of D-band/G-band) ratio of 0.23 in the Raman spectrum. Solid tubular shape with 30 nm diameter of CNFs was observed using FE-SEM and HR-TEM. Thermodynamic analyses indicate that CO2 hydrogenation into CNFs is a spontaneous and exothermic reaction with an optimal temperature of 500 degrees C.