Hydrogen Production By Decomposition Of Water In A Reducing Atmosphere Of A Mixed Conductor Oxygen Permeable Membrane

In recent years,environmental issues and energy situation is getting worse.This is urgent the new alternative energy sources that needed to find.Hydrogen energy has zero pollution and high calorific value characteristics,which was favored by countries around the world.There are variety of techniques to production hydrogen,one of the most studied was the thermochemical decomposition of water to hydrogen production.Thermochemical decomposition of water to hydrogen production has experienced a process from the chemical chain to using mixed conducting oxygen permeable membrane materials for hydrogen production.After extensive reviewing literatures,three kinds of perovskite oxides(La0.9Ca0.1FeO3-??BaFe0.9Zr0.1O3-? and La0.6Sr0.4Co0.8Ga0.2O3-?)with stable structure were selected as the research object under reducing atmosphere in this thesis.The three kinds of mixed conducting oxygen permeable membrane materials were characterized and evaluated respectively.Finally,their structural stability and thermochemical decomposition of water to hydrogen performance were studied in reducing atmosphere through the XRD,Raman and SEM methods.In this thesis,La0.9Ca0.1FeO3-?(LCF-91),BaFe0.9Zr0.1O3-?(BFZ-91)and La0.6Sr0.4Co0.8Ga0.2O3-?(LSCG-6482)perovskite-type oxygen transport membrane were prepared by sol-gel method.XRD,TG-DSC and H2-TPR were used to characterize the phase composition,the change of heat and mass during the formation process and the redox performance.The activity was evaluated by CH4-TPR and CO-TPR experiments.Then the mixed conducting oxygen permeable membrane was coupled with the membrane reactor and the oxygen permeation performance and hydrogen production performance were evaluated in the reactor.It was found that LCF-91,BFZ-91 and LSCG-6482 had better oxygen permeability at 900? and the highest oxygen permeability were 1.65,2.28 and 3.06×10-8 mol·s-1 cm-2 in the oxygen permeation experiment respectively.Three kinds of membrane materials after the oxygen permeation experiments were characterized by XRD and SEM,and the results show that LCF-91,BFZ-91 and LSCG-6482 oxygen permeable membrane materials have a dense structure,good stability before and after the reaction.The mixed conducting oxygen permeable membrane materials LCF-91,BFZ-91 and LSCG-6482 oxidation side of hydrogen production and reduction side of products were analyzed in the water splitting experiments under reducing atmosphere respectively.It was found that LCF-91,BFZ-91 and LSCG-6482 membranes were easy to production hydrogen by water splitting and the hydrogen production performance was good.It also analyzed that the membrane materials by the XRD,SEM and Raman spectra after the hydrogen production reaction.The results show that the structure of mixed conducting oxygen permeable membrane materials LCF-91,BFZ-91,and LSCG-6482 were stable after hydrogen production reaction.