Abatement of automotive cold-start hydrocarbon emissions

This paper reports the results of a study on adsorption properties of zeolitic materials with different pore openings and Si/Al ratio towards engine cold-start hydrocarbon emissions. Some selected zeolites were deposited on cordierite honeycomb support by a novel technique. Dynamic adsorption tests were performed at the engine exhaust on both commercial and specifically synthesized powder samples and on deposited zeolites. In order to obtain indications on selectivity properties of the different materials, equilibrium isotherm curves and dynamic tests were carried out for three model hydrocarbons (ethylene, isobutene, toluene) considered as representative of the most concentrated compounds detectable at engine start-up. The aim was to understand how the physico-chemical characteristics of the adsorbent material can affect its trapping capability in adsorbing all the types of hydrocarbons present in the engine exhaust. The final goal of the research is the realization of a prototype of hydrocarbon trap for abatement of cold-start hydrocarbon emissions.