Reactivation of NiSO4/ZnO-Al2O3-SiO2 adsorbent for reactive adsorption desulfurization

Abstract

NiSO4/ZnO-Al2O3-SiO2 adsorbent as a novel adsorbent for the reactive adsorption desulfurization (RADS) process performs a higher activity and lower nickel loading than NiO/ZnO-Al2O3-SiO2 adsorbent. Under reaction conditions with high temperature and high pressure, the reactivity of adsorbents inevitably decreases after long-term use. Therefore, the deactivation and reactivation of the adsorbent need to be well understood. Here, we choose model fuel and FCC gasoline as the feedstock to observe the different deactivation causes. The ZnS formation and carbon deposition are the main reasons for the deactivation. Then, we conduct different regeneration methods and conditions to optimize for different kinds of deactivation. Segmenting regeneration is adopted to ensure the effective removal of carbon deposition while avoiding excessive temperature rise. The effectiveness of the regeneration method was verified by multiple cycle experiments. The analysis of the product shows that the loss of olefin is lower here than that of NiO/ZnO-Al2O3-SiO2 adsorbent. At last, the reactivation mechanism of NiSO4/ZnO-Al2O3-SiO2 adsorbent has been studied. Of note is that since the main active site NiSx is stable during regeneration, reactivated NiSO4/ZnO-Al2O3-SiO2 adsorbent has higher initial RADS activity than NiO/ZnO-Al2O3-SiO2 adsorbent. These results guide the continuous long-term use of NiSO4/ZnO-Al2O3-SiO2 adsorbent and provide a new strategy for the design of RADS adsorbent.