Application Of Perovskite Materials In The Anode Of Solid Oxide Fuel Cell And Dry Reforming Of Methane

Perovskites have the general formula of ABO3,approximately 90%of the metallic elements of the Periodic Table are known to be stable in a perovskite-type oxide structure.Besides,both A and B site ions can be partially substituted by alien metals to form multi-cation substituted perovskites with different physical and chemical properties.Because of these facts,perovskites are widely applied to many fields.In this paper,we mainly studied the application of perovskite-type mixed oxides in solid oxide fuel cell(SOFC)and dry reforming of methane(DRM).The main achievements are as follows:1.Generating an electron-blocking layer with BaMn1-xNixO3 mixed-oxide for Ceo0.8Sm0.2O2-?-based solid oxide fuel cellsDoped ceria(DCO)has high oxygen ionic conductivity,but the electronic conduction due to the reduction of Ce4+ to Ce3+ degrades its usage as an electrolyte material for solid oxide fuel cells.Inserting an electron-blocking layer is an attractive solution to this problem.In order to generate a Ba-containing electron-blocking layer for DCO-based single cells,we applied BaMn1-xNixO3(x = 0,0.25,0.5)mixed-oxide as an anode precursor material and studied the solid reactions of it with NiO and SDC under the cell preparation conditions.XRD analyses indicate that the BaMn1-xNixO3 precursors are primarily BaMnO3/BaNiO3-? mixed-oxides.It is found that BaMn1-xNixO3 reacts with SDC to form BaCeO3 and a novel Ba2(NiMnCe)2O6 double perovskite.SEM/EDS analyses reveal that BaCeO3 tends to accumulate at the anode-electrolyte interface as well as to fill the closed pores in the SDC electrolyte.A 4 ?m-thick electron-blocking layer with BaCeO3 as the main component effectively eliminates the internal-short-circuit and enhances the performance of the cell.The open circuit voltage and peak power density of the cell with such an electron-blocking layer are 1.010V and 621 mW cm-2 at 650 ?,respectively.2.Effects of Mn partial substitution of LaNiO3 catalyst precursors for the dry reforming of methaneCatalysts originated from LaNiO3 perovskite-type precursors have higher catalytic activity and carbon resistance in DRM as compared with catalysts prepared by impregnation.However,carbon deposition cannot be completed eliminated by using LaNiO3 perovskite-type catalyst precursors.B-site partial substitutionin LaNiO3 is one of the effective methods to further improve the carbon resistance of the catalysts.In this research,LaNi1-xMnxO3(x=0.5-1.0)were synthesized by a citric acid-nitrate gel combustion method and used in dry reforming of methane.The effects of Mn on the performance of catalyst were studied.XRD analyses indicate that LaNi1-xMnxO3 completely decomposes to Ni,La2O3 and MnO.The catalyst in the actual reaction is Ni supported by La2O3-MnO.TEM analyses indicate the active Ni particles are small and uniformly disperse and the size is distributed in the range of 20-30 nm for the Ni/La2O3-MnO catalysts obtained by the decomposition of LaNi1-xMnxO3.The results of DRM tests at 850 ? indicate CH4 and CO2 conversions can reach over 90%for catalysts prepared from LaNi1-xMnxO3 precursors,which is much better than that of Ni/La2O3-MnO catalysts prepared by impregnation.The carbon resistance of the LaNi1-xMnxO3 samples gradually improves with the increase of Mn content,and no carbon deposition is detected after 5 h DRM tests of the high-Mn LaNi0.1Mn0.9O3 sample.