Abstract
The products formed in the sulfidation of zinc ferrite sorbent consisted mainly of microcrystalline ZnS and FeS, which aggregated together, and each crystal diameter was smaller than that of the initial zinc ferrite ZnFe2O4. Sulfidation of the sorbent reduced the BET surface area and destroyed the smaller pores preferentially. Those structural property changes were enhanced at the higher temperatures. The greater initial surface area of zinc ferrite gave a higher one of sulfided sorbent. Sulfate tended to be formed at the lower temperature on regeneration with air oxidation. The lower oxygen concentration depressed sulfate formation even at the lower temperature, but the regeneration was not complete due to the presence of unconverted Fe2O3 and ZnO. The greater surface area of regenerated sorbent was given by the higher one of sulfided sorbent as well as by the lower temperature. It was concluded that the optimal sulfidation and regeneration temperatures were respectively 773K and 973K in order to keep a high desulfurization efficiency with the least possible structural destruction of sorbent on cyclic operation of sulfidation and regeneration. The results obtained confirmed the idea that prevention of the primary fine particles of sorbent from aggregation and sintering during both sulfidation and regeneration leads essentially to higher performance of the desulfurization sorbent.
