Scale-up reactivation of spent S-Zorb adsorbents for gasoline desulfurization

Abstract

Reactivating and recycling spent S-Zorb adsorbents reduce fresh adsorbents consumption and hazardous wastes emissions. Though the spent adsorbents have been successfully reactivated in the laboratory, a pilot-scale practice is indispensable before the industrial production. Herein, the reactivation of spent adsorbents was performed at laboratory (1.0 L), middle (10 L) and pilot (3000 L) scale, respectively. The inert Zn2SiO4 and ZnS over the spent adsorbents are recovered to active ZnO, and the NiS is transformed into NiO. There is almost no amplification effect in pore structure and acidity of the reactivated adsorbents, while NiO particle size reduces slightly with the reactivation scales. The computational fluid dynamic simulation indicates that enhanced contact between spent adsorbents and acid/alkaline reagents at larger scale account for the smaller NiO particle. It provides more hydrogenolysis centers for CS bonds breakage after reduction, increasing initial desulfurization activity. More importantly, the adsorbent reactivated at pilot scale exhibits comparable activity to the fresh one in gasoline desulfurization. The sulfur content in the outlet decreases to less than 10 μg g−1 from 1 h of reaction. Thus, the reactivation of spent S-Zorb adsorbents is successfully scaled up to the pilot scale, accelerating industrial practice in recycling the spent adsorbents.