Preparation And Study On The Catalyst Of Polycomponent Replace Of The La₄BaCu₅O_13+δ

The article deals with the composition of the catalysts and its catalysis principle and designs the ingredient of the catalyst with full theoretical basis. The compound La4BaCu5O13+ is the most appropriate three-way purified catalyst instead of the noble metal catalyst in the theory. The favorable purify effect can be achieved relying on the synergistic action by the way of dopping Ce, Sr, Co and Ni in the position of A or B of the La4BaCu5O13+.A series of materials having the perovskite-like structure were prepared by the sol-gel method with many factors considered, including the blending method, the initial PH of the solution, complexing agent, dispersant and water bath temperature. Some significative conclusions were drawn with the systematic test of the macroscopical and microcosmic physical property of the material by the DTA-TG, XRD, BET and SEM.The best process conditions are: the molar ratio of the citric acid and the metal nitrates is 1.5; the metal nitrates solution are blended first, then adds the citric acid solution into it; adopting the glycerin as the dispersant; adjust the PH up to 8.0 and the water bath temperature is 80掳C; vacuum drying for about 14 hours.The SEM test results indicate that the grain size of the material become bigger with the temperature rising but the granulometric distribution has a still uniform distribution. The grain size of the material prepared by dopping Sr in the position "A" or dopping Co or Ni in the position "B" of the La4BaCu5O13+ is small but it becomes bigger by dopping Ce in the position "A" of theLa4BaCu5O13+ .The XRD spectrum of the material prepared by dopping Co and Ni in the position "B" of the La4BaCu5O13+, indicates that there are still some foreign matter phase at 750 C and the material has a single perovskite-like structure at 900 C.The BET test results indicate the specific surface area of the material can beincreased by dopping Sr in the position "A" of the La4BaCu5O13+ but dopping Ce reduce the specitic surface area of the material. The specific surface area of the material prepared at 900 C by dopping Co or Ni in the position "B" of the La4BaCu5O13+8 is increased about 10% than that of the material prepared by the traditional method.The pore size distribution tests find that the material prepared by dopping Ce in the position "A" of the La4BaCu5O13+ has bigger pore diameter and smaller bore volume. This result has a mutual corroboration with the BET test result. At the same time the pore diameter becomes bigger with the temperature rising.