Iron Oxides Derived From Metal-Organic Frameworks For Desulfurization

Due to their low density,high porosity and large specific surface area,porous metal oxides show promising applications in optics,electricity,magnetism and catalysis.Traditionally,porous metal oxide is prepared by utilizing hard template,which is removed by physic or chemical interactions after replicating its original nanostructure.However,the hard template method usually involves tedious procedures,and requires the use of toxic reagents,such as HF.Metal-Organic Frameworks(MOFs)are novel porous materials,which is self-assembled by metal ions and organic bridging ligands,and the MOFs are ideal precursors for preparation of porous metal oxide even without the use of template.However,the applications of porous metal oxides derived from MOFs in catalysis are still not fully explored,especially in desulfurization.The aim of this dissertation is focused on the development of an efficient strategy for controllable synthesizing porous iron oxide by utilizing MOFs as precursors.The as-prepared iron oxide were evaluated with respect to the catalytic hydrolysis of COS and selective catalytic oxidation of H2S.The relation among the morphology,structure and properties of the investigated catalysts were also discussed,aiming to provide useful information for synthesizing high-efficiency porous iron oxide.The main conclusions are summarized as follows:(1)The MIL-53(Fe)was successfully prepared by a simple solvothermal method.The morphology of MIL-53(Fe)can be further modified by the addition of HAc,and after calcination Fe2O3 porous oxide with similar morphology is obtained.The as-prepared Fe2O3 is effective in COS hydrolysis and removal of the as-produced H2S simultaneously.The one with spindle morphology(Fe2O3-3H)shows the best performance.The reason is that more active sites are found for the Fe2O3-3H.Meanwhile,their particle size can also affect their performances.(2)H2S produced by the hydrolysis of COS can be irreversibly absorbed on Fe2O3,hence the Fe2O3 should be periodic regenerated.In order to continuous desulfurization,the as-prepared Fe2O3 porous oxides were used for the selective oxidation of H2S.It is found that the Fe2O3 shows high H2S conversion and sulfur selectivity as well as excellent catalytic stability.(3)Fe3O4/C composites with different morphologies were synthesized by the calcinations of MOFs in N2 at 550 ?.The catalyst without HAc modification(Fe3O4/C)shows the best performance in COS hydrolysis and removal of the as-produced H2S.The reason may be ascribed to their larger specific surface area,thus more reactants(COS)can be adsorbed.Moreover,the Fe3O4/C catalyst also exhibits excellent catalytic performance in selective oxidation of H2S.