Abstract: Reactive adsorption desulfurization (S Zorb) is a key technology for ultra-deep desulfurization of FCC gasoline while preserving octane number. However, industrial adsorbents show significant differences in olefin saturation activity. In this study, spent and regenerated adsorbents from two industrial S Zorb units with distinct olefin saturation capacities were analyzed. Their structure, morphology, surface chemical states, active sites, and carbon deposition were characterized by XRD, TEM, H2-TPR, XPS, and TG-MS. The higher performance adsorbents (JLDS/JLZS) exhibit highly dispersed Ni species (3—5 nm) with strong metal-support interactions and abundant low-coordination sites, enabling efficient H2 activation and forming easily removable disordered carbon. In contrast, the low-activity adsorbents (YPDS/YPZS) contain aggregated Ni particles (10—30 nm) with weak interactions and mainly terrace sites, favoring the formation of graphitized carbon that is difficult to remove, thus leading to low hydrogenation activity and poor regeneration performance. Then a negative feedback loop in industrial operation could further formed: performance decline → operational compensation → excessive regeneration temperature → structural deterioration→ performance decline. This study provides a scientific basis for performance diagnosis, lifetime prediction, and long-term stable operation of S Zorb adsorbents via optimization of adsorbent consumption and other operating parameters.

Key words: S Zorb, adsorption desulfurization, Ni/ZnO adsorbent, olefin saturation, structure-activity relationship, coke