Improvement of Laboratory Tests for Evaluating Three-Way Catalyst Activity

A variety of lightoff and sweep tests were developed to characterize the performance of three-way catalysts using a computer-controlled laboratory reactor. Both fresh and thermally aged pelleted catalysts were characterized using these lightoff and sweep tests.

For all of the lightoff and sweep tests, the aged catalyst showed a loss of performance when compared to the fresh catalyst. Although the tests which use a cycled environment show better agreement with engine dynamometer tests, the non-cycled tests were generally better able to distinguish between fresh and thermally aged catalysts. These results imply that while the laboratory reactor can perform tests which closely simulate the dynamic behavior of engine exhaust under closed-loop control, non-cycled tests may be more useful in ranking catalysts for durability.