a chemical process would make automobile catalytic converters more efficient in reducing air pollutants. Chaitanya Narula and his colleagues at the chemistry department of Ford Motor Company Research Laboratory in Dearborn, Michigan, have developed the sol-gel technology that would target emissions during first 90 seconds of starting the vehicle.

Most catalytic converters turn harmful combustion products such as hydrocarbons, carbon monoxide and nitrogen oxides into harmless water, carbon dioxide and nitrogen. However, during the first one and half minutes, the converters do not reach the ideal operating conditions and maximum conversion effici-ency. During this period, nearly 70 per cent of the total air pollutants discharged during a normal driving cycle are given out the atmosphere.

To reduce automobile emissions, one potential method can be to place the catalytic converter near a vehicle's engine, where it will be warmed up more quickly. But this will only increase operating temperature of the entire converter, whereas reducing the lifetime of catalyst needed to promote the degeneration of pollutants.

The catalyst developed by the researchers would withstand the higher operating temperatures and have more surface area for treating pollutants. A form of praseodymium oxide has also been developed that efficiently stores oxygen used in the conversion reactions. In both cases, the team used sol-gel techno-logy that is a method of making ceramic and glass-like materials at room temperature instead of high temperatures.

Narula and colleagues have devised a method of heating the converter electrolytically. For this, an electrical conducting layer has been developed that a manufacturer could apply to the structure of the converter before the catalyst layer. Studies show that a full-size converter could warm to operating temperatures in about 10 seconds without taxing the battery.

The researchers have also fitted an on-board sensor to monitor the performance of the catalytic unit continuously. They used the sol-gel process to apply a thin layer of catalyst to one side of a silicon membrane, mounted near the tailpipe of the exhaust system. If hydrocarbon pollutants slip through the converter, the side will warm up, and the resulting change in electric potential will alert the car's computer.