Activity of Fe2O3 with a high index facet for bituminous coal chemical looping combustion: a theoretical and experimental study

摘要

In this work, the reactivities of Fe2O3(104) and Fe2O3(001) at different oxidation states, as well as the regeneration properties, were comparatively studied theoretically and experimentally. Firstly, interactions between a bituminous coal model molecule and the perfect and reduced Fe2O3(104) and Fe2O3(001) surfaces under different temperatures were investigated by molecular dynamics. The results proved that the perfect and reduced Fe2O3(104) surfaces can effectively promote the adsorption of fuel molecules on the OC surface. Further, deep redox properties of Fe2O3(104) and Fe2O3(001) were studied by density functional theory calculations, which suggests that oxygen transport initiated from Fe2O3(104) occurs more easily than from Fe2O3(001), which will favor the combustion of coal. Moreover, Al2O3-supported Fe2O3(104) was synthesized via morphological-control to perform bituminous coal CLC experiments in a thermogravimetric analyzer (TGA). The comparison between reaction of Fe2O3(104)/Al2O3 and bituminous coal and reaction of bituminous coal and the referenced Fe2O3/Al2O3 which was prepared by the traditional impregnation method verified that the former shows a higher fuel conversion and less carbon residue. The regeneration of Fe2O3(104)/Al2O3 was characterized by XRD and SEM. The high miller index surface iron oxide OC is shown to be efficient and rewarding for use in CLC of solid fuel.