Research On Preparation Technique And Aging Of Metallic Honeycomb Catalyst For Automotive Exhaust Purifying

Automotive exhaust is the main source of air pollution now. Generally enginemodification and after-treatment control technique are used for this problem, andsetting three-way-catalyst, one of after-treatment control, is the most effective solution.At present, the hot issues about three-way-catalyst include improving cold-startperformance, reducing noble metal dosage and prolonging the used life.Firstly, noble metal supported honeycomb catalysts were prepared by thecommercial technique and according to exhaust catalyst system temperature and agingcharacteristics are studied. The results show that the property of catalysts was in inertstate and high temperature disposing didn't reach the goal of aging, instead improvedthe catalytic activity. Therefore, some researches were put up as following.Supported catalysts with different calcination temperature were prepared by theimpregnated method and the effects of calcination on catalyst properties and structurewere investigated. The results show that calcination had some great effects on catalystproperties, and the best calcination temperature was between 650℃～750℃ . Underthe optimized conditions, some reasons contributed to catalytic oxidation activityimproved. One of these was forming ceria-zirconium solid solution in catalyst surface,the other one was that Palladium have the form of PdOx/Pd in existence and mightcome into being the new form of Ce1-xPdxO2-δ solid solution.Two series catalysts of low content palladium, which had different wash-coat andactive component, were prepared by the impregnated method, and temperature andaging characters are studied. The results show that the sample, which had wash-coatof alumina with the additive ceria-zirconium solid solution and the co-catalyst of V,Cu, had the best oxidation activity. Reducing a great lot of noble metal dosage (from0.6g/Lcat to 0.2g/Lcat) didn't seriously lead to catalytic activity decline, and it isfeasible to choose 0.2g/Lcat as noble metal dosage.According to the optimized technique and formula, the catalytic converter wasprepared. Making use of WY125-16D motorcycles with closed-loop control EFIsystem, adopting DPC-1 motorcycles chassis dynamometer in turn drum test platform,emission properties of original motorcycles, 1000km and 10000km were measured inthe light of CEC-40 running mode. The results show that the emission of motorcyclesfixed catalytic converter met European Ⅱstandard, and the decline reason of catalyticproperties was mainly carbon deposition. The key to improving catalytic propertiesand life was scientific design of catalytic converter.