Desulfurization of High-Sulfur Jet Fuel by (pi)-Complexation with Copper and Palladium Halide Sorbents

Deep desulfurization of a high-sulfur jet fuel (for fuel cell applications) was achieved by adsorption with (pi)-complexation sorbents. The total sulfur content of JP-5 jet fuel was removed from 1172 ppmw S to below 1 ppmw S. The following sorbents were prepared and tested: CuCl supported on activated carbon (CuCl/AC), PdCl2/AC, PdCl2/Al2O3, and Cu(I)-Y zeolite. Comparison of these sorbents as well as other known sorbents showed that PdCl2/AC had the highest sulfur selectivity and capacity. It was found that significant breakthrough occurred at about 6.0 mL/g for desulfurization of JP-5 by PdCl2/AC. Ab initio molecular orbital computation was performed for the bond energies between different sulfur molecules and these sorbents. For methylated benzothiophene, the main sulfur molecules in jet fuels, the bond energies (and the separation factors for organosulfur/benzene) followed the order PdCl2 > CuCl > Cu-Y. This result was in agreement with the experimental breakthrough data. The spent PdCl2/AC was regenerated with benzene in a static system, and the regenerated sorbent was tested for reuse. The results showed that ~74 wt % adsorbed sulfur could be desorbed and 72% of the sulfur capacity could be recovered for reuse.