Engines, gasoline powered emissions from

The Diesel engine has excessive emission of smoke and odor from aldehydes and oxygenated aromatics, which are not regulated at this moment. It is approximately 50% larger and heavier than a gasoline engine of the same horse power. However, it does have the virtue of better fuel economy and easier maintenance. 

Natural gas (NG) consists of 85-95% methane (CH ), which is the simplest hydrocarbon. NG is the cleanest burning alternative fuel. Exhaust emissions from NG vehicles are much lower than those from gasoline-powered vehicles. Combustion of NG reduces carbon dioxide content compared with diesel, but the lost efficiency when the Otto process is used means that carbon dioxide emissions increase. All in all combustion of NG in a gasoline engine gives rise to about as much carbon dioxide as the combustion of diesel in a diesel engine, measured in units of energy. 

Hadnagy W, Seemayer NH. 1988. Cytotoxic and genotoxic effects of extract of particulate emission from a gasoline-powered engine. Environ Mol Mutagen 12 385- 396. 

Hadnagy W, Seemayer NH. 1989. Genotoxicity of particulate emissions from gasoline-powered engines evaluated by short-term bioassays. Experimental Pathology 37 43-50. 

A major difference between diesel engines and gasoline powered engines is that the potential for controlling hydrocarbons in diesel exhaust through exhaust catalysts is very poor. The most that can be expected is some form of trap to contain diesel particulates. This may also be effective in controlling PNA, since a substantial part of the PNA emission from diesels is associated with the solid material. 

Nevertheless, secondary measures are mostly still needed to reduce exhaust emissions of cars to meet current emission standard in most countries. These so-called end-of-pipe solutions are based on the catalytic conversion of all HCs, CO and NO (three-way catalyst). The success of the monolithic catalytic converter (which has a lower pressure drop than a fixed bed) is up to now limited to gasoline powered engines. However, in recent years progress has been made in the development of catalytic filters for the cleaning of exhaust gas (e.g., particulate matter) from diesel engines. 

Anthropogenic sources of NgO include adipic and nitric acid production, fossil fuel and biomass combustion, land cultivation, and vehicle emissions. " NgO emissions from gasoline-powered engines have been related to the aging of three-way catalysts (TWCs) and NgO is also emitted as a by-product of Pt-based prototypic catalysts for the selective catalytic reduction (SCR) of NO with hydrocarbons in diesel engine exhausts. ... 

Emissions from the consumption of diesel fuel are low, however. There is virtually no evaporation. In 1969, hydrocarbon emissions from diesel-powered vehicles in the USA amounted to 200,000 t (as compared with 16.9 million t from gasoline engined vehicles) [13]. Of this figure, the Cio-C24-hydrocarbons account for a relatively low portion, but are nevertheless responsible for the offensive odour [13]. A few hundred different components have been found, some are components of the diesel oil but others are formed by combustion [13]. The more important constituents are indanes, tetralines, alkyl benzenes, naphthalenes, indoles, acenaphthenes, and benzothiophenes [13]. It appears that the quantitatively less important aromatic aldehydes and ketones are responsible for the odour [13]. At a rough estimate, the total world emissions of alkyl benzenes and naphthalenes must amount to some 200,000 t. Diesel particulate emissions contain neutral fractions with microbial mutagenic activity [26 a]. 

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