Under normal operating conditions, catalytic converters appear to be the most effective means of reducing air pollution from SI engines. The conversion efficiency, however, declines very steeply for temperatures below about 350 °C and is practically zero during the starting and warming-up period. Improving the conversion efficiency under these conditions is important, particularly in large cities, where the number of starting per vehicle per day tends to be high. Among the other solutions are preheating of the catalyst electrically, warming up of the catalyst in an external combustion chamber, installation of an auxiliary small-capacity catalytic converter, and employment of an adsorbing unit between two catalysts. Although these methods are quite effective, their disadvantage lies in the fact that they require an external energy source, an additional component (a control unit) or a three-stage catalyst. An Cold-Start Emissions Adsorber System (CSEAS) for reducing cold-start emission (HC,NOx and CO) have been developed combining existing catalyst  technologies with a zeolite based Adsorber. The series flow in-line concept offers a passive and simplified alternative to other technologies by incorporating one additional existing converter with additional valving, purging lines and secondary air.

Important technical issues to be resolved for practical use of this CSEAS are,

1. The ability to absorb a wide range of HC, NOx and CO in the exhaust gas.

2. The temperature difference between emissions desorption from the Adsorber and activation desorbed emission.

The CSEAS reduced up to 100% of cold-start emissions beyond the three-way catalyst only base line system [1] . The in-line CSEAS could be one of the potential technologies to meet EURO-V and future regulations without the need for ancillary electrically and its associated costs.