The performance of structured cobalt catalysts in Fischer-Tropsch synthesis
type: CreativeWork
description: Cobalt is the preferred catalyst metal for the production of clean burning, high cetane number diesel fuel from synthesis gas using the Fischer-Tropsch synthesis. Hence, increasing C5+ selectivity of cobalt catalysts is one of the hot topics in Fischer-Tropsch synthesis. Internal mass transport limitation may affect C5+ selectivity. It was concluded that mild transport limitation is required for maximum C5+ selectivity. Mild transport limitation also increases the catalyst activity, since the reported Fischer- Tropsch rate of reaction has a negative dependency on CO partial pressure. The metal distribution within catalyst pellets may modify product selectivity by changing the local metal density and the diffusion path length. However, current catalyst preparation methods limit metal distribution in transition metal catalysts. The aim of this study is to explore a possible catalyst synthesis route for egg-shell, egg-yolk and egg-white type of cobalt catalyst pellets. The establishment of the nonuniform cobalt catalyst synthesis method will provide an observational evaluation technique for the investigation of the effect of intra-pellet metal distribution on the activity and product selectivity of the Fischer-Tropsch synthesis. The non-uniform catalyst synthesis method utilises the hydrophobic nature of the silica pellet. Egg-shell, egg-yolk and egg-white type of cobalt catalyst with sharp metal enriched boundary were synthesized. The intra-pellet cobalt distribution, metal particle size, metal loading, metal surface area and catalyst reducibility were characterised. The performance of these non-uniform catalysts was tested in a modified slurry type reactor. Catalyst pellets were kept in mesh-wire baskets which were mounted inside a slurry reactor, and tested in the absence of external mass transport limitation. The Fischer-Tropsch activity was recorded and modelled using a reaction-diffusion pellet inside a continuous stirred tank reactor model. The product selectivi…
abstract: Cobalt is the preferred catalyst metal for the production of clean burning, high cetane number diesel fuel from synthesis gas using the Fischer-Tropsch synthesis. Hence, increasing C5+ selectivity of cobalt catalysts is one of the hot topics in Fischer-Tropsch synthesis. Internal mass transport limitation may affect C5+ selectivity. It was concluded that mild transport limitation is required for maximum C5+ selectivity. Mild transport limitation also increases the catalyst activity, since the reported Fischer- Tropsch rate of reaction has a negative dependency on CO partial pressure. The metal distribution within catalyst pellets may modify product selectivity by changing the local metal density and the diffusion path length. However, current catalyst preparation methods limit metal distribution in transition metal catalysts. The aim of this study is to explore a possible catalyst synthesis route for egg-shell, egg-yolk and egg-white type of cobalt catalyst pellets. The establishment of the nonuniform cobalt catalyst synthesis method will provide an observational evaluation technique for the investigation of the effect of intra-pellet metal distribution on the activity and product selectivity of the Fischer-Tropsch synthesis. The non-uniform catalyst synthesis method utilises the hydrophobic nature of the silica pellet. Egg-shell, egg-yolk and egg-white type of cobalt catalyst with sharp metal enriched boundary were synthesized. The intra-pellet cobalt distribution, metal particle size, metal loading, metal surface area and catalyst reducibility were characterised. The performance of these non-uniform catalysts was tested in a modified slurry type reactor. Catalyst pellets were kept in mesh-wire baskets which were mounted inside a slurry reactor, and tested in the absence of external mass transport limitation. The Fischer-Tropsch activity was recorded and modelled using a reaction-diffusion pellet inside a continuous stirred tank reactor model. The product selectivi…
author: Zhuang, Youqi
language: eng
date published: 2009
date modified: 2026-07-22T22:23:01Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Chemical Engineering

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/5381