title: Sulfur evolution in chemical looping combustion of coal with MnFe2O4 oxygen carrier.
abstract: Chemical looping combustion (CLC) of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operational or environmental perspective. In this research, a combined MnFe2O4 oxygen carrier (OC) was synthesized and its reaction with a typical Chinese high sulfur coal, Liuzhi (LZ) bituminous coal, was performed in a thermogravimetric analyzer (TGA)-Fourier transform infrared (FT-IR) spectrometer. Evolution of sulfur species during reaction of LZ coal with MnFe2O4 OC was systematically investigated through experimental means combined with thermodynamic simulation. TGA-FTIR analysis of the LZ reaction with MnFe2O4 indicated MnFe2O4 exhibited the desired superior reactivity compared to the single reference oxides Mn3O4 or Fe2O3, and SO2 produced was mainly related to oxidization of H2S by MnFe2O4. Experimental analysis of the LZ coal reaction with MnFe2O4, including X-ray diffraction and X-ray photoelectron spectroscopy analysis, verified that the main reduced counterparts of MnFe2O4 were Fe3O4 and MnO, in good agreement with the related thermodynamic simulation. The obtained MnO was beneficial to stabilize the reduced MnFe2O4 and avoid serious sintering, although the oxygen in MnO was not fully utilized. Meanwhile, most sulfur present in LZ coal was converted to solid MnS during LZ reaction with MnFe2O4, which was further oxidized to MnSO4. Finally, the formation of both MnS and such manganese silicates as Mn2SiO4 and MnSiO3 should be addressed to ensure the full regeneration of the reduced MnFe2O4.
authors: College of Electric Power, North China University of Water Conservancy and Hydroelectric Power, Zhengzhou 450045, China; State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China. Electronic address: david-wn@163.com.
authors: Baowen
authors: B
authors: Wang
authors: College of Electric Power, North China University of Water Conservancy and Hydroelectric Power, Zhengzhou 450045, China.
authors: Chuchang
authors: C
authors: Gao
authors: College of Electric Power, North China University of Water Conservancy and Hydroelectric Power, Zhengzhou 450045, China.
authors: Weishu
authors: W
authors: Wang
authors: State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China.
authors: Haibo
authors: H
authors: Zhao
authors: State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China.
authors: Chuguang
authors: C
authors: Zheng
mesh_terms: D000393:Air Pollutants / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry; D003031:Coal / Q000032:analysis*; D004784:Environmental Monitoring; D005290:Ferric Compounds / Q000737:chemistry*; D007220:Industrial Waste; D017895:Manganese Compounds / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D000393:Air Pollutants; D003031:Coal; D005290:Ferric Compounds; D007220:Industrial Waste; D017895:Manganese Compounds; C551151:manganese ferrite; D002245:Carbon Dioxide; D013455:Sulfur; D010100:Oxygen
keywords: CO(2) capture; MnFe(2)O(4); chemical looping combustion; sulfur evolution