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The effect of total olefin content on ozone forming potential has been widely studied. As a result a stringent limit for olefins is already given in California Specification for “Phase 2” gasoline and the 18 vol% limitation of olefins is expected to tighten also in Europe. However, it is not clear how determining the light olefins are and what is the role of heavy olefins regarding ozone forming potential. Ethanol is widely used as gasoline component in many countries, but not extensively in Europe. The biofuels have the potential to provide a renewable source of energy and contribute to lower global CO2 emissions. The unregulated emissions, especially particulates and their quality have not been studied extensively with ethanol containing gasoline using European test fleet. The objective was to study the applicability of heavy olefins in non-oxygenated and ethanol oxygenated gasolines. Alkylates in gasoline were replaced by isooctene.

Plans to ban MTBE (Methyl tertiary-Butyl Ether) have led to discussions on how the gasoline in California will be formulated without any backsliding in air quality. One possibility is to replace MTBE with isooctane. Exhaust emissions using California Phase II gasoline with MTBE, were compared to a gasoline where MTBE had been replaced with isooctane. Regulated, particulate, carbon dioxide, and PAH (polyaromatic hydrocarbons) emissions were measured at 22 °C temperature for 8 vehicles using the European cycle for year 2000 (ECE+EUDC). One of the vehicles was a GDI (Gasoline Direct Injection), one was a carbureted model without a catalytic converter, and the others were equipped with multi point fuel injection and catalytic converters. Results indicate that no major backsliding in air quality can be expected when replacing MTBE with isooctane. NOx (nitrogen oxides) emissions were reduced in all vehicle types. CO emissions increased in the vehicle without a catalytic converter.

Exhaust emissions from cars using reformulated gasoline (RFG) that meets European 2005 regulations for gasoline quality were compared to the emissions from cars using gasoline that meets European 2000 regulations (EU2000). Methyl Tertiary Butyl Ether (MTBE) and Tertiary Amyl Methyl Ether (TAME) were used as oxygenates in the reformulated gasoline. The EU2000 gasoline contained no oxygen. Regulated, particulate and PAH exhaust emissions were measured at 22°C for 7 cars and at -7°C for 5 cars using the European MVEG cycle for year 2000 (ECE+EUDC). One of the cars was equipped with a lean burn engine, one with a direct injection engine and one was a carburetor equipped car without a catalytic converter. All other cars were equipped with multi point port fuel injection and a catalytic converter. Mutagenic activity of particulate mass was evaluated using the Ames test.