Study On The Preparation, Structures And Perfromance Of LaCoO₃Perovskite-based NSR Catalysts

Firstly, a series of supported LaCo1-xCuxO（3x=0，0.1，0.2，03,0.5）NSR catalystswere prepared by polymerizable complex method using MCM-41molecular sieves assupport. The as-obtained catalysts possessed high BET surface area (63-131m2/g),and pure perovskite crystal structure. When B site element Co was partiallysubstituted by element Cu, some high valence Co3+δ（0＜δ＜1）metal ions would beproduced，improving the redox property of the catalysts. The NSC and NSRexperiment results show that the ratio of the doped Cu has important effect on theperformance of the catalysts.Secondly, the independent mesoporous LaCoO3catalysts (M-LaCoO3) with highsurface area (45-100m2/g) were synthesized by nano-casting method using SBA-15molecular sieves as hard template. To improve the NOx storage capacity (NSC), weloaded5wt%K2CO3on M-LaCoO3, and investigated the NSC, NOx storage/reduction(NSR) performance as well as the reaction mechanism of these catalysts. The resultsindicate that this catalyst exhibits excellent performance for NO oxidation and NSRafter cycles of alternating lean/rich atmospheres at350oC. A NOx removal efciencyas high as97.0%and a NOx to N2selectivity of about97.3%was achieved over thiscatalyst. After16lean/rich cycles, the perovskite phase was well maintained, showinghigh structural stability. Ionic potassium nitrates have been identified as the mainNOx storage species.At last, a series of La1-xKxCoO3catalysts were prepared by using sol-gel method,NOx storage capacity and NOx removal efficiency of this catalyst were investigated.The impact of K-doping on the structure and catalytic property of the catalysts wasalso studied by using the techniques of XRD, SEM, BET, TPR and FT-IR.