(430b) Enhancement of Adsorptive Desulfurization of Hydrocarbon Fuels by Silver Adsorbents On Titania Dispersed Supports for Fuel Cell Application

Fuel cell systems such as PEMFC require fuel having trace amount of sulfur. To reach such low concentration the sulfur removal process in the refinery needs to be more severe which increases its cost. Adsorptive desulfurization in ambient conditions offers a promising solution, having several advantages such as its selectivity, regenerability and zero hydrogen usage. Among the group of regenerable oxide sorbents, Ag/TiO₂ sorbent has one of the highest desulfurization capacities. Titania support contributes significantly to the overall capacity of Ag/TiO₂ sorbent due to its greater amount of surface functional groups but it is limited by its overall surface area. In this work, the performance of sorbents with titania dispersed supports for desulfurizing Ultra Low Sulfur Diesel (ULSD, 6.5 ppmw S) have been discussed. Titania was dispersed onto high surface area alumina and silica supports by incipient wetness method and surface area and active sites concentration were measured by nitrogen physisorption and ammonia chemisorption, respectively. Number of surface functional groups was increased by dispersing titania onto high surface area silica and alumina support, which in turn enhanced the sulfur adsorption capacity. 4% by weight Ag on TiO2-SiO2 and TiO2-Al2O3 support showed equilibrium saturation capacity of 0.45 and 0.37mg S/g sorbent, respectively for challenge ULSD at room temperature. Desulfurization was also carried out using model fuel. X-ray Diffraction (XRD) found no titania/titanium peaks indicating it is dispersed onto support surface as nanoparticle up to 10%Ti loading. Effect of preparation method was studied by SEM-EDX and support prepared by incipient wetness was observed to have greater presence of titania onto the surface.