Study on the Aging Test Methods and the Properties of the Three-Way Catalysts

The activity and durability are two important parameters in characterizing the properties of three-way catalysts. The durability of three-way catalysts can be tested by various aging methods. In China these aging methods usually include: the simulated engine bench aging method corresponding to the on-vehicle aging of 80,000 kilometers, and the 80,000-kilometer on-vehicle track aging method. The results of the two aging test methods can differ; therefore the different catalyst producers and the different catalyst users need to compare the results from the different aging test methods.

The engine bench aging method and the vehicle track aging method were used in this study. The three-way catalyst in a converter was aged for 100 hours on the engine bench. A similar three-way catalyst placed in a car was aged for 80 thousand kilometers on the vehicle track. Both of the aged three-way catalysts were tested in China according to the emission regulation of GB 18352.1-2001, which is similar to the ECE urban cycle and the EUDC extra-urban cycle. The emissions of CO, HC and NO_x were measured through the two aged three-way catalysts, and compared. According to the emissions test results, the engine bench aging method showed more aging characteristic on the three-way catalyst than the vehicle track aging method. In general, catalysts that were designed to the specification of GB 18352.1-2001 or GB 18352.2-2001 in China (i.e. EURO I or EURO II in Europe) would comply with the emission specifications after 80 thousand kilometer aging on a vehicle track test, and after a 100 hour aging on the engine bench test.