Aldehyde, Ketone and Methane Emissions from Motor Vehicle Exhaust: A Critical Review

Recent data indicate that, in many countries, mobile sources are responsible for the largest portion of emissions of aldehydes, ketones and certain other air toxic pollutants. These air toxic pollutants along with methane are either carcinogenic or pose significant human health threat. These pollutants also add to global warming in a substantial way. This paper gives an overview of their properties, basic chemistry and conditions of formation in internal combustion engines. Again worldwide many countries are promoting alternative fuels to tackle the crisis of traditional fuel. But the impact of this movement toward alternative fuels with respect to toxic emissions has not been well studied. Therefore, in this paper the analysis on the effects of engine operation and fuelling parameters is also reviewed with specific references in gasoline, diesel, natural gas, liquefied petroleum gas, ethanol blended petrol and Biodiesel fuelled engines. This is accompanied by the review of the studies of the performance of exhaust catalytic converters with respect to aldehydes, ketones and methane. Additionally, aldehydes, ketones and methane detection and measurement methods are summarized and analyzed from the view of their applicability to exhaust gas analysis.