Submitted to: Annual Meeting and Expo of the American Oil Chemists' Society
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2004
Publication Date: May 1, 2004
Citation: Hess, M.A., Haas, M.J., Foglia, T.A. 2004. The effect of antioxidant addition on nox emissions from biodiesel [abstract]. 95th Annual Meeting of the American Oil Chemists' Society. p. 69-70. Technical Abstract: Biodiesel is a renewable, domestically produced fuel that has been shown to reduce particulate and carbon monoxide emissions from diesel engines. Biodiesel produced from certain feedstocks, however, has been shown to cause an increase in nitrogen oxides (NOx), which is of particular concern in urban areas that are subject to strict environmental regulations. There are several pathways proposed that try to account for NOx formation during the combustion process, one of which is the Fenimore mechanism. In the Fenimore mechanism, it is postulated that fuel radicals formed during the combustion process react with nitrogen from the air to form NOx. We proposed that if these radical reactions could be terminated, NOx production from biodiesel combustion would decrease. To test this hypothesis, the ability of antioxidants to terminate these radical reactions and reduce NOx levels in biodiesel exhaust was investigated. Several antioxidants added to a 20% biodiesel/80% diesel fuel blend (B20) were screened using a small minimally instrumented diesel engine to test their ability to reduce NOx emissions from the fuel. The engine used for these studies was a single cylinder, direct injection, air-cooled, naturally aspirated Yanmar engine. The NO and NO2 in the exhaust stream were quantified using electrochemical sensors, and differences in NOx emissions from the combustion of B20 with and without antioxidant compared. Preliminary data show that antioxidant addition does not significantly decrease or increase NOx emissions. This information is pertinent in light of the possibility that antioxidant addition will be employed to improve the storage stability of biodiesel.