Abstract
This paper will present a comparison of different catalytic coatings especially designed for small motorcycle application with regard to activity, durability and precious metal costs. Since recent catalytic formulations for this application widely use rather expensive platinum (Pt) -rhodium (Rh) formulations, this paper will present data for less expensive coatings which use palladium (Pd) as the main or the only active precious metal compound. Besides the fresh catalytic activity the thermal and chemical aging stability will be compared for PtRh, PtPdRh and Pd-only formulations. We will show that also less expensive Pd-rich catalytic coatings can be used for an effective emission reduction of small motorcycles.
The presented data have been obtained by synthetic gas reactor testing using a simulated engine exhaust gas for coated catalysts as well as for thermally and chemically aged catalysts. Chemical aging was performed by impregnation of poisonous elements like Ca, Zn and P simulating a real life aging process; thermal aging was performed in an oven.
In addition, the activity of different formulations has been tested using a 125cc motorcycle, running the ECE R40 cold-start cycle which is used for the Euro 3 and China 3 emission regulation for motorcycles. These results will be correlated with the results of the synthetic gas reactor tests.