Synthesis Of Electrospun Pt/LaCoO₃ Catalysts And Their Catalytic Properties For Propane Oxidation

More and more seriously enveiromental problems are affecting people's healthy life with the rapid development of human industry.Volatile organic compounds(VOCs)as one kinds of important air pollutants,mainly come from automobile exhaust and industrial discharge.Catalytic oxidation is an excellent method to eliminate VOCs because of its advantages of high efficiency and without secondary pollution.In all series of catalysts,Pt based noble catalysts show excellent activity at low temperature but tends to be sintered.LaCoO3 perovskite shows high thermal stability but has poor low-temperature catalytic activity.Therefore,preparing high dispersion of Pt/LaCoO3 catalyst has important significance for eliminating VOCs by catalytic oxidation methodIn this research,several series of Pt/LaCoO3 catalysts were synthesised using the combined methods of electrospinning and incipient wetness impregnation.Their structures and physicochemical properties were investigated by XRD,SEM,TEM,N2 physical adsorption,H2-TPR,O2-TPD,TPSR,elemental analysis,in situ DRIFTS,XPS and ICP-AES.Furthermore,their catalytic performances for the total oxidation of propane were tested.The specific contents are as follows.(1)The influence of using different kinds of reductants such as H2,NaBH4,ethylene glycol and Eucalyptus extract on the performances of catalytic propane oxidation were investigated.The results show that using H2 as reducing agent will enhance the low-temperature redox ability and oxygen mobility.In addition,loading Pt on LaCoO3 will increase surface adsorption of oxygen species,which are beneficial for propane oxidation For the catalysts using ethylene glycol and Eucalyptus extract,much of residual carbon causes low catalytic oxidation activity.(2)In order to solve the problem of Pt NPs aggregation when using ethylene glycol as a reductant,He+O2+H2 annealing strategy was used,which can play a positive effect of PVP residual carbon sourse for promoting Pt dispersition.According to experimental results,residual PVP carbon source coats on Pt NPs in the annealing atmosphere of He,decreasing surface energy and hindering the migration of Pt NPs.Then,using O2 atmosphere can eliminate surface carbon source of PVPR Finally,treating the catalyst in the atmosphere of H2 can ensure Pt atoms being high dispersed Pt0.(3)In order to investigate the interaction between noble metal Pt and LaCoO3 hollow CA-Pt/LaCoO3 catalyst was prepared in one-step by coaxial electrospinning technology.It is revealed that Pt atoms are distributed on surface and superficial zone of LaCoO3 support.This results in abundant contents of Co3+ and surface active oxygen speciesJthus a superior performance for propane catalytic oxidation.