Mixed metal oxide containing iron with the high-sulfur capacity and reactivity is considered as one of the most favorable sorbents for desulfurization in hot gas. The stability and life of iron-based sorbents are the main challenges for the hot gas cleanup techniques. Not only the effect of gas atmosphere but also the effect of ZnO and MgO on the stability of iron-based sorbent was studied in this work. The mechanism and factors influencing sorbent stability are discussed. The results showed that the coexistence of CO and H 2 result in the instability of the zinc-iron-based sorbents. The reaction of carbon deposit is the crucial step affecting the stability of sorbent for hot gas desulfurization. ZnO in the sorbent is adverse to the physical stability of the iron-based sorbents. MgO in the sorbent hardly affects the physical stability of the iron-based sorbents but improves the capacity of removing the hydrogen sulfide from hot coal gas at 773 K.
The sulfidation behaviors of iron-based sorbent with MgO and MgO-TiO2 are studied under different isothermal conditions from 623 to 873 K in a fixed bed reactor. The results of sorbents sulfidation experiments indicate that the sorbents with MgO and TiO2 additives are more attractive than those without additives for desulfurization of hot coal gas. The sulfur capacity (16.17, 18.45, and 19.68 g S/100 g sorbent) of M1F, M3F, and M5F sorbent containing 1, 3, and 5% MgO, respectively, is obviously bigger than that (15.02 g S/100 g sorbent) of M0F without additive. The feasible sulfidation temperature range for M3F sorbent is 773−873 K. The M3F sorbent is optimally regenerated at the temperature of 873 K, under the gas containing 2% oxygen, 15% steam and N2, in the space velocity of 2500 h−1. The sorbent regenerated is also well performed in the second sulfidation (the effective sulfur capacities of 17.98 g S/100 g sorbents and the efficiency of removal sulfur of 99%). The capacity to remove sulfur decreases with steam content increasing in feeding gas from 0 to 10%, but it can restrain the formation of carbon and iron carbide. The addition of TiO2 in sorbent can shift the optimal sulfidation temperature lower. The iron-based sorbent with 3% MgO and 10% TiO2 (MFT) is active to the deep removal of H2S and COS, especially in the temperature range of 673−723 K. The sulfur removal capacity of MFT sorbent is 21.60 g S/100 g sorbent.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.