A reformulated diesel fuel ‘Citydiesel’ reduces particulate emissions of diesel vehicles by 10 to 30% and NO, by 2 to 10% compared to standard fuel. Polyaromatic hydrocarbons in exhaust are reduced by 50 to 70% and mutagenic activity by 40 to 70%. Cold start smoke is reduced and exhaust odor is less unpleasant.

Emissions reduce immediately also in old vehicles which have a great influence on the urban air quality.

Sulphur content of Citydiesel is below 50 ppm, aromatic content below 20% and cetane number over 47.

Final boiling point and the amount of heavy aromatics in the fuel was reduced to cut harmful emissions.

Catalytic converters can be used in trucks and buses to reduce emissions further due to the very low sulphur content.

Fuel consumption, aging of lubricating oil and wear of injection pumps were monitored with Citydiesel in a 3.0 years field test using 140 city buses. Experience was good. Citydiesel was made commercially available after modifications in refinery processes. Citydiesel is, for example, an excellent fuel for fork lift trucks used in warehouses and for loaders in mines, too.

Emissions can be reduced remarkably by combining modern diesel engines, catalytic converters and reformulated diesel fuels. Total costs will be clearly lower than by using alternative fuels like alcohols, LPG or GNC.


Diesel emissions and their possible effects on health are receiving increased attention. Over 30 test fuels with different compositions were formulated and their emissions were measured. The final composition for a reformulated diesel fuel ‘Citydiesel’ was developed based on the results of these tests.

Maximum sulphur content of diesel fuel will be reduced from the present 0.2% to 0.05% by 1996 in Europe. Citydiesel contains sulphur already less than this level at 0.005% (50 ppm).

Polyaromatic hydrocarbons (PAHs) which are found in the high boiling fraction of the fuel, may be emitted in the exhaust. Some PAHs are mutagenic and carcinogenic. The amount of PAHs in the exhaust have been lowered by reducing PAHs in the fuel by selecting the most appropriate distillation range and composition for Citydiesel.

Total aromatic content of Citydiesel is limited to be below 20% which is less than for diesel general. 2. SULPHUR FREE FUEL NEEDED CATALYTIC CONVERTERS fuels in FOR The amount of carbon monoxide (CO) and hydrocarbons (HC) in diesel exhaust can be reduced by a catalytic converter. The particulate bound soluble organic fraction (SOF) and thus the amount of PAHs are also reduced. However, high sulphur content (>0.05%) in the fuel changes the operation of the converter by increasing the particulate emissions compared to an engine without a converter.

The very low sulphur content of Citydiesel (0.005%) will ensure efficient operating conditions for catalytic converters. The adva

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