Effect of cobalt supported on meso-macro porous hydrotalcite in Fischer-Tropsch synthesis

Abstract

Hydrotalcite based cobalt catalysts were prepared by a slurry precipitation method, followed by a slurry impregnation method. The prepared supports and catalysts were characterized by N-2 physisorption, mercury intrusion, chemisorption, TPR, TPD, SEM, TEM, TGA, DTA, and XRD techniques. Their catalytic performance for FTS was evaluated in a fixed-bed reactor with a H-2/CO molar ratio of 2, reaction temperature of 240 degrees C, and reaction pressure of 25 bar. The incorporation of alumina and kaolin enlarged the inter void between hydrotalcite clusters, which resulted in macro porosity. The cobalt catalyst supported on a bimodal pore structure induced by kaolin showed a more stabilized catalytic activity and better heavy hydrocarbon selectivity in the FTS reaction when compared to other catalysts. The catalytic performance of the prepared catalyst depended on the cobalt reducibility and diffusion efficiency, which were determined by the cobalt particle size and porosity.