Evaluation of Zeolites as Hydrocarbon Traps for Cold Start Applications
Annalisa Tosti, University of Virginia
Hydrocarbon traps are being developed to assist the Diesel Oxidation Catalyst (DOC) during cold start periods of the engine operation. In fact, in the first few minutes after engine ignition, the temperature of the exhaust gases is lower than the light off temperature of the catalyst required for the hydrocarbon (HC) oxidation and any unburnt HC is directly released into the atmosphere. A possible approach, to meet the more severe regulations on vehicle emissions, is to employ absorbers, which can trap, retain, and release the HCs once the DOC becomes lit-off. Zeolites have been found to be useful for this application due to their tunable chemical and acid base properties and their thermal stability.
This poster will show the results of a laboratory study conducted on some zeolites, incorporating metallic species within their frameworks. Their trapping behaviors were investigated in the presence of representative hydrocarbon species (and potential inhibitors), under simulated but realistic emission conditions. The zeolite performances, as hydrocarbon traps at low temperatures, are evaluated, focusing on their hydrocarbon storage capabilities and desorption temperatures.