280503 Diffusion of n-Hexane in Mesoporous Ceria-Zirconia-Yttria Catalyst Supports

Wednesday, October 31, 2012
Hall B (Convention Center )
Alma I. Morales and David A. Bruce, Chemical and Biomolecular Engineering, Clemson University, Clemson, SC

Ceria-zirconia-yttria (CZY) mixed oxides are used as catalyst supports for three-way catalyst for automotive exhaust emission control and in solid oxide fuel cell technology. The ordered arrangement of CZY mesopores is believed to help prevent sintering and by that enhance their catalytic performance during emission treatment. However, limited studies have been published on the effect of CZY pore morphology in catalysts operation. This study gives insight into diffusion effects and pore morphology since diffusion is a main aspect of catalyst performance during emission treatment.  

The diffusion of n-hexane in mesoporous ceria-zirconia-yttria (CZY) supports with pore diameters between 4 and 8 nm is studied by the Zero Length Column (ZLC) Method. The behavior of hexane inside mesoporous CZY is derived by analysis of the desorption curves obtaining not only the diffusion coefficient but also the effect of purge flow rate and temperature among other variables in the system. The results show diffusivity is strongly dependent on temperature and allow us to analyze the effects of pore morphology in the diffusion behavior of n-hexane inside the CZY catalyst supports.  The ZLC technique is proven to be valuable to understand the diffusion kinetics of gasses inside mesoporous CZY and the effects of different pore morphologies, especially ordered versus disordered mesopores in the diffusion behavior of gasses.

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