The regeneration mechanisms of sulfurized α-Fe2O3 desulfurization sorbent under O2 atmosphere are systematically studied by density functional theory(DFT)slab calculation.The regeneration pathways are proposed for two sulfurized surfaces,“S-contained surface” and “S-adsorbed surface”,which are derived from the substitution of surface O atom by S atom and the adsorption of S atom on the surface Fe atom,respectively.Our results show that two competitive regeneration pathways exist on each sulfurized surface.For the regeneration on the S-contained surface and the S-adsorbed surface,the rate-determining step is the dissociation of O2 with the energy barriers of 136.7 and 227.3 kJ·mol-1,respectively,suggesting that the regeneration on the Scontained surface is easier than that on the S-adsorbed surface.Then,the O vacancy on the α-Fe2O3(0001)surface can be repaired under O2 atmosphere,and the reparation mechanism demonstrates that the dissociation of O2 on the O-vacancy α-Fe2O3(0001)surface only needs to overcome a lower energy barrier of 49.8 kJ·mol-1 than those(136.7 and 227.3 kJ·mol-1)on two sulfurized surfaces.As a result,the presence of O vacancy on the α-Fe2O3(0001)surface can accelerate the dissociation of O2,which is favorable to the regeneration of sulfurized surfaces.