Effect of complexing species in a sol-gel synthesis on the physicochemical properties of La_(0.7)Sr_(0.3)Mn_(0.7)Cu_(0.3)O_(3+lambda) catalyst

摘要

A series of La_(0.7)Sr_(0.3)Mn_(0.7)Cu_(0.3)O_(3+lambda) 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 NH_3 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.