Eggshell catalysts for Fischer-Tropsch synthesis - Modeling catalyst impregnation

This study presents a successful methodology to produce Co-Zr on silica eggshell catalysts. It is shown that parameters such as impregnation time, metal solution concentration, solution viscosity, as well as the state of the support before impregnation, strongly influence the evolution of the thickness and the final state of the metal in the eggshell catalyst. It is demonstrated that the wet impregnation, using low metal concentration solutions improves metal dispersion by producing a more progressive eggshell profile than the dry impregnation. Mathematical models were used to describe both the dry impregnation, effected with low and high metal concentration solutions, as well as the wet impregnation, effected with low metal concentration solutions. These models include either no adjustable parameter (dry impregnation) or a single adjustable parameter (wet impregnation) and lead to reliable predictions of the formation of the eggshell. (C) 2001 Elsevier Science B.V. AU rights reserved.