The use of a volatile liquid fuel to reduce cold-start emissions from a spark ignition engine

As traffic density increases, there is growing urgency to reduce its polluting effect. Catalysts fitted to new vehicles, with spark ignition engines, are highly efficient at controlling harmful emissions once they have reached operating temperature. However, during a cold-start the catalyst is initially inactive, just when engine-out emissions are at their highest, mainly due to the fuel-rich mixtures used for reliable starting and good driveability, particularly at low ambient temperatures. As the population of vehicles fitted with catalysts grows, the significance of this cold-start and warm-up period of operation will increase. [Continues.]