A study on the reduction of cold start hydrocarbon from gasoline engines using hydrocarbon adsorbers

Experiments were carried out to investigate the characteristics of the hydrocarbon (HC) emissions and to reduce cold start hydrocarbons in gasoline engines. An HC adsorber was, used and it coated was by Pd/Rh catalyst with zeolite on a honeycomb monolith. The HCs were efficiently trapped at temperatures below 100°C by physical adsorption. After adsorption, they were reduced gradually by the catalytic oxidation of Pd/Rh catalysts as the adsorbert temperature increased above 100°C. Increasing amounts of methane, ethylene and n-butane were emitted as the fuel-air mixture became richer and the engine speed decreased. As the temperature of adsorber increased, high-number carbons into low-number carbons. Thus, the C4 concentration decreased significantly during the first 30 seconds, and the C2 concentration increased continuously.