Pre- and post-catalyst-, fuel-, velocity- and acceleration-dependent benzene emission data of gasoline-driven EURO-2 passenger cars and light duty vehicles |
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Institution: | 1. Department of Chemistry, Faculty of Metallurgy and Material Engineering, V?B – Technical University of Ostrava, 708 33 Ostrava – Poruba, Czech Republic;2. Regional Materials Science and Technology Centre, V?B – Technical University of Ostrava, 708 33 Ostrava – Poruba, Czech Republic;3. ENET Centre - Energy Units for Utilization of Non-traditional Energy Sources, V?B – Technical University of Ostrava, 708 33 Ostrava – Poruba, Czech Republic |
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Abstract: | The benzene emission characteristics of six gasoline-driven EURO-2 vehicles, three passenger cars and three light duty vehicles, have been determined by time-resolved chemical ionization mass spectrometry. Aliquots of the exhaust gas were monitored pre- and post-catalyst with two independently operating mass spectrometers. Each vehicle was driven with two different fuels having benzene contents of 1 and 2 vol%. Seven driving cycles—including the European (EDC) and the US (FTP-75) driving cycle—with a total driving time of about 8800 s were studied. Herein, we discuss the average emission characteristics of the entire fleet at transient driving in the velocity range of 0–150 km h?1. The conversion efficiencies of the involved catalytic systems were deduced from the pre- and post-catalyst data. On average, the vehicles showed optimal benzene conversion efficiencies (>95%) in the velocity range of 30–90 km h?1. When driving below 20 or above 100 km h?1 reduced benzene conversion was found (80–82%). No benzene conversion was observed when driving above 130 km h?1. In contrast, the post-catalyst benzene emissions exceeded those of the untreated exhaust gas by 19–49%. Thus on an average, benzene was formed across the catalysts under these conditions. In addition, the influence of the benzene content of the gasoline on the tail-pipe emissions was also studied. The use of the gasoline with 1 vol% benzene instead of 2 vol% induced a 20–30% reduction of the post-catalyst emissions when driving below 50 km h?1. The fuel effect became smaller above 100 km h?1 and was even negative at high engine load (>130 km h?1). Thus under these conditions, when benzene is formed across the catalyst, the amount of the emitted benzene was independent of the benzene level of the fuel. |
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