Deactivation due to sulfur poisoning and carbon deposition on Rh-Ni/Al2O3 catalyst during steam reforming of sulfur-doped n-hexadecane

Deactivation by sulfur poisoning and carbon deposition of steam reforming catalyst used for hydrogen production from diesel or jet fuel creates a significant barrier to commercialization of fuel cell technologies. Steam reforming of n-hexadecane on a rhodium/nickel catalyst supported on gamma-alumina, a formulation previously proposed for steam reforming of logistic fuel, was used to study the deactivation mechanisms. The steam reforming activity was measured in terms of H-2 yields and showed that the catalysts were stable in the absence of sulfur but deactivated over a period of 10 h when sulfur was present at high loading. Stability and activity were higher with higher amounts of Rh content when Ni was kept constant. TEM-EDS of used catalysts revealed preferential adsorption of sulfur on the surface of Ni crystallites: EDS and XRD analysis showed no bulk sulfide formation. Excessive carbon deposition was observed during steam reforming of sulfur-containing fuel. Blocking of reactant species on the surface of the catalyst due to the formation of aromatic/polymeric carbon on the support was also seen, although higher Rh content inhibited this phenomenon. (C) 2009 Elsevier B.V. All rights reserved.