Catalyst Systems with an Emphasis on Three-Way Conversion and Novel Concepts

The effects accruing from the choice of precious metals and their relative ratios are considered in catalyst systems used in VW and AUDI cars under open loop conditions and dynamic closed loop controlled engine conditions in conjunction with an exhaust gas oxygen sensor. The best catalyst system for three-way activity found when comparing major manufacturer technologies was the system Pt/Rh = 5:1 which is introduced in two 1979 engine families sold in California, VW microbus and Audi 5000.

This paper discusses also the interrelationship between window and sensor characteristic and novel emission control concepts including metal supported catalysts and catalysed exhaust pipes for the improvement of warm-up.