Tortuosity of mesoporous alumina catalyst supports: Influence of the pore network organization

Svetan Kolitcheff (1) , Elsa Jolimaitre (1) , Antoine Hugon (1) , Jan Verstraete (1) , Pierre-Louis Carrette (1) , Mélaz Tayakout-Fayolle (2)

1 IFPEN - IFP Energies nouvelles
2 LAGEP - Laboratoire d'automatique et de génie des procédés

Inverse liquid chromatography experiments were performed on five mesoporous alumina catalyst supports with similar porosity and different pore size distributions. By varying the size of the molecular tracer, it was shown that the diffusion regime in our conditions is molecular diffusion. Hindered diffusion was not observed even for squalane, a C 30 molecule. Using the slope of the Van Deemter equation, the tortuosity of each alumina support was determined. The results are in disagreement with literature correlations: although all alumina supports had similar total porosities, the measured tortuosity values are really different and much higher than those predicted by these theoretical models. This discrepancy has been resolved by assuming a two–level pore network organization, whose characteristics can be entirely estimated from a classical nitrogen adsorption isotherm. This simple methodology allows to evaluate the mass transfer in mesoporous alumina supports knowing their textural properties, which is an important issue for the design and optimization of numerous catalytic processes.

Keywords: Pore network; Tortuosity; Internal diffusional limitations; Alumina support; Inverse liquid chromatography; Pore size distribution

Domains: Catalysis; Material chemistry

Svetan Kolitcheff, Elsa Jolimaitre, Antoine Hugon, Jan Verstraete, Pierre-Louis Carrette, et al.. Tortuosity of mesoporous alumina catalyst supports: Influence of the pore network organization. Microporous and Mesoporous Materials, 2017, 248, pp.91-98. ⟨10.1016/j.micromeso.2017.04.010⟩. ⟨hal-01581729⟩