Diesel vehicles today emit far less pollutants than older vehicles, thanks to a zeolite catalytic converter that was invented around 10 years ago. Although many groups have investigated this catalyst since then, it was still unclear why it is so much more effective. By managing to see inside the catalyst in three dimensions at the nano scale level, researchers from Utrecht University and Oak Ridge National Laboratory (ORNL) in the US have now found the explanation. After simulating 217,000 km of wear, they compared a ‘new’ and an ‘old’ version of the catalyst in detail. This revealed the current catalyst retains much more of its ‘younger’ structure than previously used diesel catalysts. The researchers also found the underlying reasons as to why this catalyst is so much more stable over its lifespan, and experiences only minimal damage compared to previously used catalysts. The results are published today in Nature Communications.
Diesel catalytic converters are exposed to frequent temperature changes, extremely hot steam, and pollutants, but they must remain stable for the entire life of the vehicle. That stability is due in part to the complexity of the catalyst. “At first glance, zeolites may seem easy to understand, but the more you study them, the more fascinated you become by their complexity”, says Joel Schmidt (Utrecht University), the publication’s lead author.