The efficient removal of refractory organosulfur compounds, such as dibenzothiophene, remains a critical bottleneck in achieving ultra-low sulfur diesel standards. While oxidative-adsorptive desulfurization is promising, there is a significant research gap in rationally designing adsorbents that utilize synergistic multi-metal active sites to enhance the capture of sterically hindered species. To address this, we synthesized a novel multi-metal ion-exchanged zeolite (AgNiCeY) via a sequential ion-exchange process, aiming to strategically incorporate Lewis acid sites (Ag+, Ni2+, Ce3+) within the NaY framework. BET surface area for NaY and AgNiCeY was 623 and 540 Formula: see text respectively. The desulfurization performance and underlying adsorption mechanisms were rigorously evaluated. Using response surface methodology (RSM) on a model fuel system (DBT in n-octane) ), the optimal capacity was determined at a contact time of 55 min and an oil/adsorbent ratio of 18. 2 ml/g. The resulting AgNiCeY adsorbent demonstrated a remarkable increase in equilibrium adsorption capacity from 12. 61 mg/g (NaY) to 33. 26 mg/g, marking a 164% enhancement. Mechanistic analysis, supported by FT-IR and electronic structure visualization, confirms that the synergy between the exchanged cations acts as Lewis acids, facilitating superior σσ-bond formation with the sulfur atom. Crucially, when tested under realistic conditions using real diesel fuel containing 2544 ppm sulfur, the modified AgNiCeY maintained high efficiency, achieving a 61. 3% sulfur removal, significantly outperforming the parent NaY (57. 8%). This study validates a novel design principle for heterogeneous catalysts, demonstrating that precise, sequential multi-metal exchange in zeolites offers a robust and scalable strategy for improving the selective adsorption of refractory sulfur compounds. Regeneration experiments were also conducted to assess the recyclability of the catalysts over multiple cycles.
Shafaghat et al. (Mon,) studied this question.