(717e) Selective Adsorption of Refractory Organosulfur Compounds From Low Sulfur Commercial Fuels by Novel Regenerable Sorbents at Room Temperature

Fuel cells have opened a new frontier towards the development of high efficiency engines, but the need for ultra low sulfur fuels limits their applications. Multi-cycle adsorption of sulfur species at ambient conditions offers an alternative solution to inexpensive ultra clean fuels. In this work, the adsorption of predominant C2-dibenzothiophene from commercial ultra-low sulfur diesel (ULSD) by silver based sorbent has been discussed. The sorbent (1 mm average particle size) was able to selectively adsorb the predominant refractory organosulfur compound (ROSC) in ULSD, 4, 6-dimethyldibenzothiophene to the tolerance range of PEMFC's and low temperature SOFC's which require parts per billion (ppbw) sulfur level. 4% by weight Ag/TiO2 showed equilibrium saturation capacity of 0.2 mg of sulfur/g of sorbent for 6.5 ppmw initial sulfur concentration in the challenge ULSD. The selectivity of Ag/TiO2 towards ROSC in ULSD over moisture, alcohol and additives which are typically present in ULSD was examined by using model fuels which showed a pronounced affinity between them. In the breakthrough test, a guard bed of Al2O3 followed by Ag/TiO2 increased the breakthrough sulfur capacity, while keeping negligible pressure drop. 100% of the sulfur capacity of the sorbent against ULSD was retained after multi-cycle regeneration of the sorbent in air at temperatures ranging from 110-450°C.