Effect of complexing species in a sol–gel synthesis on the physicochemical properties of La0.7Sr0.3Mn0.7Cu0.3O3+λ catalyst

A series of La0.7Sr0.3Mn0.7Cu0.3O3+λ perovskite-type catalysts were prepared by a sol–gel method with citric acid–ammonia binary complex. The samples were evaluated by catalytic activity tests in the simulated exhaust and characterized by XRD and BET analyses. The three-way catalytic activities, phase structure and specific surface areas of the samples fluctuated according to the acid/ammonia ratio. It was found that adding a certain ratio of NH3 into the precursor could modify the complexing process. The sample prepared at critic acid/ammonia = 1:1.5 shows an optimized catalytic performance with more structure defaults formed. Comparably, the worst structure integrality and catalytic activity was obtained at acid/ammonia = 1:3.5. And, the corresponding complexing models were presented to give a further discussion.