Development of ceria-supported sulfur tolerant nanocatalysts: Pd-based formulations

The conversion of logistics fuels (JP-5, JP-8, Jet-A and diesel) to hydrogen by steam reforming is attractive but poses great challenge since these fuels contain sulfur up to about 3000 ppm leading to catalyst deactivation due to sulfur poisoning. In this paper, we report the fabrication of nominally doped nanoscale ceria-supported palladium catalyst matrices for their performance evaluation in sulfur-laden fuel streams. Systematic structural and microstructural characterization of the catalysts was carried out before and after the steam reforming and simulated experiments in sulfur containing streams (50 ppm < S < 1000 ppm) over a wide range of temperature and duration, to speculate and understand the deactivation mechanism and the sulfur tolerance aspects. Steam reforming of toluene as a model fuel without or with 50 ppm sulfur (as thiophene) was carried out at 825 degrees C and steam to carbon (S/C) ratio of 3. It was found that the addition of metal oxide additives yielded more stable and sulfur-tolerant formulation. (c) 2007 Elsevier B.V. All rights reserved.