Hydrocarbon Trapping over Ag-Beta Zeolite for Cold-Start Emission Control

Toluene, hexane, ethane, ethylene and CO adsorption and desorption on/from model Ag-exchanged beta zeolites were evaluated. The presence of water significantly inhibited adsorption of ethylene below 100 A degrees C, whereas hexane and toluene adsorption were not affected. The addition of Ag increased adsorption capacities and desorption temperatures for both ethylene and toluene, while no difference was observed for hexane. Under conditions containing all hydrocarbons, ethylene adsorption was absent, and the toluene adsorption rate decreased. Results with binary mixtures demonstrate the inhibition of ethylene adsorption is due to toluene and the slower rate of toluene adsorption is caused by hexane.