Afton’s Paper SAE 2007-01-1078

"The Interaction of mmt® Combustion Products with the Exhaust Catalyst Face"

Overview:

Afton Chemical technology helps fuels burn cleaner, engines run smoother and machines last longer. We are committed to ensuring our products are environmentally safe and fully compatible with consumer expectations. In SAE paper 2007-01-1078, Afton Chemical presents results from testing the fundamental mechanisms that govern interactions between engine combustion products and exhaust catalysts. These studies address the impact of exhaust temperature, engine transients, use of the fuel additive mmt® and catalyst cell density on the accumulation of combustion products on the catalyst.

 These studies provide the following significant information:

1. The experimental test procedures used nearly 30 years ago that explained catalyst plugging mechanisms can be used to the same effect in modern vehicles fitted with close coupled high cell density catalysts;
2. When the experimental test procedure includes operating conditions associated with normal consumer driving, particle detachment forces are introduced and catalyst plugging is not measured; 
3. Real world vehicle experience and proper laboratory testing with mmt® support the study findings that mmt® does not cause catalyst plugging.

Afton understands this is an important issue and will continue to perform studies and monitor the performance of our products in the market.

Conclusions:

1. The experimental test procedures used nearly 30 years ago that explained catalyst plugging mechanisms can be used to the same effect in modern vehicles fitted with close coupled high cell density catalysts 
   
   
   • In a 1978 SAE paper, Furey and Summers demonstrated that by eliminating the normal variability vehicles and engines experience in the real world, catalysts can plug.
   • Under these experimental conditions, the rate of particle adhesion to the catalyst is a function of exhaust temperature
   • A recent paper, SAE 2007-01-1070, Honda researchers showed that under the same controlled conditions, the rate of particle adhesion to the catalyst is also a function of catalyst cell density
     
     
2. When the experimental test procedure includes conditions that exist under actual driving conditions, particle detachment forces are introduced and catalyst plugging is not measured
   
   • Afton’s study was designed to specifically include particle detachment forces. A simple periodic transient, of the type observed when a vehicle slows down, during otherwise steady state engine operation resulted in significant detachment forces.
   • Increased pressure drop is not measured when particle “detachment” or “release” mechanisms such as those associated with an exhaust temperature transient are incorporated.
   • The introduction of detachment forces to prevent increased catalyst pressure drop in lower cell density catalysts was shown to have the identical effect on high cell density catalysts
   • During typical consumer vehicle use, additional particle detachment forces are encountered that were not considered in this series of experiments and would be expected to further increase particle removal rates.
     
     
3. Real world vehicle experience and proper laboratory testing with mmt® support the study findings that mmt® does not cause catalyst pluggingchers used artificially severe experimental conditions and modified vehicles
   
   • Canadian Government documents state that the government never “received any data supporting the claims” of catalyst plugging.
   • SAE 2006-01-3405: Warranty replacement rates for catalysts and other emission control components in Canada for 2001 and newer model year vehicles were equivalent to replacement rates in two different areas of the United States, where mmt® was not used.
   • SAE 2006-01-3406: Inspection and maintenance (I/M) test failure rates in Canada were equal to or better than those measured in the United States. The vehicle model used for engine testing in Honda’s study, the 2001 Honda Civic, failed I/M testing at extremely low rates, both on an absolute basis and relative to other 2001 vehicle models and previous model year Civics.
   • SAE 2005-01-3840: A fleet test of 2004 Euro IV certified vehicles equipped with high cell density close-coupled converters showed no negative effect on emissions with mmt® use (at 18 mg Mn/liter) and no evidence of catalyst plugging.
   • China State Environmental Protection Agency (published 2006): A fleet test of Euro III certified vehicles equipped with high cell density close-coupled converters conducted to evaluate Honda’s concerns showed no negative effect on emissions and no evidence of catalyst plugging with mmt® use (at 18 mg Mn/liter).

You can request copies of any of the referenced papers through the Contact Us section of this site, or by clicking here.