Synthesis and Characterization of Cobalt-Based Nanocatalysts: Effect of Supports

This paper presents a comparative study of Co nanocatalysts supported on Al2O3, SiO2 and carbon nanotubes (CNTs). The nanocatalysts were prepared by a wet impregnation method. Samples were characterized using H2-TPR, CO-chemisorptions, H2-TPD, TPO and transmission electron microscopy (TEM). The catalytic activities of the supported Co nanocatalysts were evaluated in a Fischer-Tropsch synthesis (FTS) reaction using a fixed-bed microreactor at 543K and 1 atm, H2/CO = 2 v/v and space velocity, SV = 12 L/g.h. CNTs-supported Co nanocatalyst exhibited different physicochemical properties compared to Co supported on Al2O3 and SiO2. The CNTs support resulted in better dispersion, improved reducibility, increased in the CO and hydrogen chemisorptions of Co compared to those supported on Al2O3 and SiO2. Amongst the catalysts studied, the Co/CNTs had the largest number of active sites which resulted in the highest CO conversion (15.7%) and C5+ selectivity (14.0%). Carbon nanotubes were found to be a better support for Co nanoparticles compared to Al2O3 and SiO2.