Ultra-deep desulfurization of ultra-low sulfur diesel over nickel-based sorbents in the presence of hydrogen for fuel cell applications

This study explored the addition of H₂ to improve the sorption performance of the nickel-based sorbents in ultra-deep desulfurization of ultra-low sulfur diesel (ULSD). The desulfurization of ULSD over Raney Nickel and Ni20/SBA-15 was conducted in a fixed-bed sorption system at 220 °C and ambient pressure in the absence and presence of H₂. Addition of very small amount of H₂ into the sorption system significantly increases the adsorptive capacity of the nickel-based sorbents for desulfurization of ULSD. The improvement of the sorption performance is through accelerating the C-S bond cracking of the adsorbed sulfur compounds to release the corresponding hydrocarbon part from the surface, and thus to provide more exposed nickel atoms on the surface to interact with other sulfur compounds. Each kilogram of the prepared Ni20/SBA-15 sorbent in the presence of H₂ is able to treat about 240 L of the commercial ULSD with sulfur content of 14.5 ppmw to get a desulfurized fuel with sulfur content less than 1 ppmw.