title: Stability of nanocrystals: thermodynamic analysis of oxidation and re-reduction of cobalt in water/hydrogen mixtures.
abstract: The stability of nanosized materials differs significantly from the stability of bulk materials. In this study a thermodynamic analysis on the simultaneous oxidation and re-reduction of small metallic cobalt crystallites in the presence of water and hydrogen as a function of the crystallite diameter was performed as a model for catalyst deactivation in the Fischer-Tropsch synthesis. It is shown that spherical cobalt crystallites with a diameter less than 4.4 nm are likely to be oxidized under realistic Fischer-Tropsch synthesis conditions (p(H)(2)(O)/p(H)(2) < 1.5, T = 493 K).
authors.affiliation: Catalysis Research Unit, Department of Chemical Engineering, University of Cape Town, Private Bag, Rondebosch 7701, South Africa. evs@chemeng.uct.ac.za
authors.forename: Eric
authors.initials: E
authors.lastname: van Steen
authors.forename: Michael
authors.initials: M
authors.lastname: Claeys
authors.forename: Mark E
authors.initials: ME
authors.lastname: Dry
authors.forename: Jan
authors.initials: J
authors.lastname: van de Loosdrecht
authors.forename: Elvera L
authors.initials: EL
authors.lastname: Viljoen
authors.forename: Jacobus L
authors.initials: JL
authors.lastname: Visagie