Enhanced adsorption desulfurization performance of metal-modified Y zeolites

Y-zeolite is a promising adsorbent for removing organic sulfides from fuel. However, its application is limited by low adsorption capacity for refractory sulfur compounds. In this study, metal-modified Y-zeolite (MY) adsorbents, incorporating Ru³⁺, Bi³⁺, Zr⁴⁺, and Sb³⁺ ions, were successfully synthesized via a solid-state reaction method. X-ray diffraction analysis confirmed that metal ion incorporation did not alter the crystalline framework of Y-zeolite. Nitrogen adsorption–desorption isotherms revealed that the Ru-modified Y-zeolite (RuY) possessed a notably high specific surface area of 735.23 m²/g, whereas NH₃-temperature programmed desorption (NH₃-TPD) measurements showed that it also had the highest concentration of acidic sites (2.375 mmol/g). The effects of metal ion type, loading amount, and oxidation state on thiophene removal were systematically investigated via batch adsorption experiments. Sulfur removal efficiency increased in the following order: HY (43%) <BiY-1 (53%) <SbY-1(62%) <ZrY-1 (63%) <RuY-1 (68%). The RuY adsorbent exhibited the best adsorption performance, with Ru4+ ions acting as the primary active sites. The adsorption behavior followed the Langmuir isotherm model, indicating a monolayer adsorption process. Sulfur removal efficiency correlated positively with the sulfur–metal (S–M) bond strength in MY adsorbents. Compared to unmodified HY, MY adsorbents also showed improved selectivity for thiophene in the presence of competing toluene. The superior desulfurization performance of RuY is attributed to its smaller ionic radius (62 pm), higher charge (Ru⁴⁺), larger specific surface area, and abundance of Lewis acid sites.