Reactivation of the spent Ni/ZnO-based adsorbent with enhanced initial activity for gasoline desulfurization

Abstract

The widespread application of the S-Zorb technique generates a large quantity of spent Ni/ZnO-based adsorbents which are hazardous wastes. Reactivation and recycling of the spent adsorbents generate huge environmental benefits, which unfortunately has not gained deserved attention. Herein, a modified acid-base coupling method was developed for reactivation of the spent adsorbents. Extra active sites of nickel are introduced into the reactivated adsorbents to improve the initial desulfurization activity. It was carried out by introducing nickel salt into the acid reactivation system followed by the precipitation process during the alkali treatment step. The obtained adsorbents were characterized systematically and the possible reactivation mechanism was disclosed. The newly formed nickel oxides are well dispersed over the reactivated adsorbents and exhibit a strong interaction with support. It favors the increase of hydrogenolysis centers for CS bonds breakage, improving the desulfurization activity. The newly reactivated adsorbent with extra 10 wt% nickel loading shows significantly improved initial desulfurization activity compared with the reactivated adsorbent without extra nickel loading. It even exhibits comparable desulfurization performance to the fresh adsorbent in gasoline desulfurization and the sulfur content in outlet meets the Euro V standard (below 10 μg g−1).