The Synthesis Metallic Oxide Catalysts With Different Morphologies By Electrospinning And Their Application For Catalytic Oxidation

CO and VOCs are the common pollutions in the air,which would cause some negative impacts on environment and human health.The catalytic oxidation technology is widely deemed as one of the main and effective methods,which process a series of advantages such as low reaction temperature,high efficiency and few secondary pollutants.Catalytic plays a pivotal role in catalytic oxidation technology.Most noble metal is one of the main active components for the catalytic combustion of CO and VOCs due to best performance,good stability and regeneration capacity.But there is a limit to the application due to high prices.Therefore,selecting ideal supports,improving dispersion of noble metal elements and decreasing the consumption are very important.As we all know,Co₃O₄ and In₂O₃ oxide are p-type and n-type semiconductor.Recently,some works of this p-n heterostructure material is a suitable support,which performs affluent gas diffusion channel,high reducibility,high specific surface area and defective structure.Based on above analyses,the synthesis metallic oxide catalysts of Pd loaded CoO_x based,Pd loaded InO_x and Pd loaded CoO_x-InO_x with different morphologies by electrospinning and their application for catalytic oxidation.Including a series of Pd loaded CoO_x-InO_x metallic oxide catalysts materials are prepared with different morphologies for CO catalytic oxidation;a series of hollow InO_x@Pd/CoO_x core-shell metallic oxide catalysts with ultra-thin shell are prepared for CO catalytic oxidation;a series of Pd/InO_x@CoO_x core-shell metallic oxide catalysts are novelly composed of Pd/InO_x nanotubes core,CoO_x nanocubes and CoO_x nanoparticles shell for toluene catalytic oxidation.Combining with the SEM,TEM,BET,H₂-TPR,XRD,CO-TPR,O₂-TPD,FT-IR,Raman,XPS and so on,the structures,chemical properties and the factors affecting the activity of samples were further investigated.The conclusions were performed as follows:A numbers of CoO_x-InO_x-500?nanofibers?,CoO_x-InO_x-600?porous nanofibers?and CoO_x-InO_x-700?bead-like structures nanofibers?were prepared by electrospinning and annealing.A numbers of Pd/CoO_x-InO_x-500?nanofibers?,Pd/CoO_x-InO_x-600?porous nanofibers?and CoO_x-InO_x-700?bead-like structures nanofibers?also prepared by impregnation method,which used in CO catalytic oxidation.The sample of Pd/CoO_x-InO_x-500 exhibited the superior CO performance with T₉₀=57°C.Through some characterizations,we discovered that the Pd/CoO_x-InO_x-500 catalyst owned larger surface area,stronger redox ability,richer defective structure and oxygen vacancy,the higher dispersion of Pd species,higher Co³⁺species and higher lattice oxygen species than Pd/CoO_x-InO_x-600 and Pd/CoO_x-InO_x-700.A series of hollow In₂O₃@Pd/Co₃O₄ core-shell nanofibers with ultra-thin shell about20-30 nm of Pd/CoO_x and core of InO_x have been successfully fabricated by coaxial electrospinning and annealing,which used in CO catalytic oxidation.Pd/CoO_x and Pd/InO_x nanofibers have been successfully fabricated electrospinning,which also used in CO catalytic oxidation.Desirably,the In₂O₃@Pd/Co₃O₄ exhibited the high CO activity with T₉₀=56°C and low activation energy.Through some characterizations,it is verified that the In₂O₃@Pd/Co₃O₄owned higher dispersion of Pd species,higher Co³⁺species,higher chemical adsorbed oxygen species,richer oxygen vacancy,richer defective structure,stronger redox ability and the stronger interaction of Co₃O₄ and In₂O₃ than others.The passivated Pd/InO_x nanofibers have been successfully fabricated by electrospinning and annealing.Afterwards,In situ growth of ZIF-67 on the surface of passivated nanofibers was synthesized Pd/InO_x@CoO_x core-shell nanofibers.CoO_x@Pd/InO_x core-shell nanofibers and Pd/InO_x/CoO_x nanofibers with different morphologies have been successfully synthesized by coaxial electrospinning and annealing for the catalytic combustion of toluene.Among them,the Pd/InO_x@CoO_x core-shell sample is novelly composed of Pd/InO_x core and CoO_x shell.On the contrary,the CoO_x@Pd/InO_x core-shell catalyst is assembled by CoO_x core and Pd/InO_x shell.Pd/InO_x/CoO_x nanofibers exhibited bead-like structures.Interestingly,the Pd/InO_x@CoO_x core-shell sample displayed the best activity for toluene oxidation with T₉₀=253°C,good thermal stability and good cyclic stability during the three runs.Through some characterizations,it is verified that the Pd/InO_x@CoO_x core-shell sample exhibited best performance for toluene oxidation reaction due to the larger specific surface area,higher reducibility,richer defective structure and oxygen vacancy,higher dispersion of Pd species,higher Co³⁺species and higher lattice oxygen species than others.