Enhanced sulfur capacity of durable and regenerable mesoporous sorbents for the deep desulfurization of diesel

The adsorptive desulfurization of a mode diesel (300 ppmw S) and a commercial diesel (187.2 ppmw S) using the durable and regenerable Ag/Al-SBA-15, Ni/Al-SBA-15 and Ce/Al-SBA-15 sorbents was investigated in fixed-bed tests. The desulfurization capability of the sorbents was remarkably enhanced by elevating metal ion-exchanging temperature, increasing metal ion-exchanging number of times and using large pore SBA-15 (∼11.55 nm) as the support. Ni/ASL60-4 sorbent, which was prepared by exchanging Ni ions onto the aluminized large pore SBA-15 (∼11.55 nm) at 60 °C with 4 of times, exhibited the highest desulfurization capability. For the desulfurization of the model diesel, Ni/ASL60-4 can remove 0.228 mmol of total sulfur per gram at saturation. For desulfurization of commercial diesel, 7.0 ml of clean diesel (less than 1.0 ppmw S) can be produced over 1.0 g of Ni/ASL60-4. The desulfurization capability of Ni/ASL60-4 can be enhanced a total of 250% compared to Ni/AS20-1. The saturated Ni/ASL60-4 was regenerated in situ by heating in dry air at 350 °C. After generation, the desulfurization capability of Ni/ASL60-4 can be completely recovered even after 3 cycles. The NiO particles were not found on the fresh and regenerated Ni-based sorbents by XRD test. This showed that metal Ni was in the form of Ni ions after the desulfurization and regeneration. This was mainly because the Ni ions can be firmly anchored on the aluminized SBA-15 by ion-exchanging.